Abstract 4: Intercepting ribosomal protein S6KB1 signaling: Prevention of prostate cancer recurrence

There is an urgent need for innovative strategies such as the discovery of adjuvants that can prevent relapse and improve quality of life for patients treated with radiotherapy. Previously we demonstrated the utility of Nexrutine (Nex) as a neo-adjuvant with radiation. Nex was safe and well tolerated in PCa patients and potentiated radiation response in part through downregulation of ribosomal protein S6K (encoded byRPS6KB1). We now show that RPS6KB1 depleted prostate cancer cells with higher basal levels of γ-H2AX, a marker for DNA double strand breaks (i) are more sensitive to radiation and (ii) form smaller tumors with reduced levels of prostate specific antigen (PSA). Depletion of RPS6KB1 hindered DNA double-strand break repair predominantly through the alternate end-joining pathway, induction of G2/M checkpoint and NFκB pathway activation. Collectively these events led to improved radiation sensitivity. We further identified Berberine (Ber), one of the active constituents of Nex as a potential pharmacological inhibitor of RPS6KB1. In an orthotopic implantation model of C4-2B, treatment with Ber alone or Ber plus radiation decreased PSA levels that was sustained during the course of the experiment. On the other hand animals treated with radiation alone developed recurrent cancer as evidenced by a resurgence of PSA. Animals administered Ber followed by XRT intervention had increased levels of RANTES while there was no change in animals that received XRT followed by Ber. The observed reversal of the Bereffect with the sequence of intervention is statistically significant (p=0.0298). Among animals not subject to XRT, the mean PSA increased in those that did not receive Ber relative to those that did; mean difference=-1.93, 95% CI -3.75 to -0.105, p=0.04 with no significant changes in body weight. Notably,RPS6KB1 mRNA levels increased in tumor samples in patients experiencing biochemical recurrence(BCR). Given that rising PSA following conventional therapeutic approaches such as radiation remain a major clinical challenge, targeting RPS6KB1 signaling with radiation therapy is an attractive strategy to prevent BCR. Supported in part by CPRIT RP190012 (APK).

Citation Format: Addanki Pratap Kumar, Alison Clark, Michelle Villarreal, Sridharan Jayamohan, Shih-Bo Huang, Suleman S. Hussain, Xiaoyu Yang, Paul Rivas, Darpan Patel, Bethany L. Pierce, Shreya Tripathy, Pawel Osmulski, Maria Gaczynska, Lai Zhao, Li-Ju Wang, Yidong Chen, Caroline Xavier Paul Ezhilan, Mohan Natarajan, Joel E. Michalek, Robert L. Reddick, Rita Ghosh. Intercepting ribosomal protein S6KB1 signaling: Prevention of prostate cancer recurrence [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4.

GLI3 Is Stabilized by SPOP Mutations and Promotes Castration Resistance via Functional Cooperation with Androgen Receptor in Prostate Cancer

Although the Sonic hedgehog (SHH) signaling pathway has been implicated in promoting malignant phenotypes of prostate cancer, details on how it is activated and exerts its oncogenic role during prostate cancer development and progression is less clear. Here, we show that GLI3, a key SHH pathway effector, is transcriptionally upregulated during androgen deprivation and posttranslationally stabilized in prostate cancer cells by mutation of speckle-type POZ protein (SPOP). GLI3 is a substrate of SPOP-mediated proteasomal degradation in prostate cancer cells and prostate cancer driver mutations in SPOP abrogate GLI3 degradation. Functionally, GLI3 is necessary and sufficient for the growth and migration of androgen receptor (AR)-positive prostate cancer cells, particularly under androgen-depleted conditions. Importantly, we demonstrate that GLI3 physically interacts and functionally cooperates with AR to enrich an AR-dependent gene expression program leading to castration-resistant growth of xenografted prostate tumors. Finally, we identify an AR/GLI3 coregulated gene signature that is highly correlated with castration-resistant metastatic prostate cancer and predictive of disease recurrence. Together, these findings reveal that hyperactivated GLI3 promotes castration-resistant growth of prostate cancer and provide a rationale for therapeutic targeting of GLI3 in patients with castration-resistant prostate cancer (CRPC). IMPLICATIONS: We describe two clinically relevant mechanisms leading to hyperactivated GLI3 signaling and enhanced AR/GLI3 cross-talk, suggesting that GLI3-specific inhibitors might prove effective to block prostate cancer development or delay CRPC.

Androgen deprivation-induced elevated nuclear SIRT1 promotes prostate tumor cell survival by reactivation of AR signaling

The NAD⁺-dependent deacetylase, Sirtuin 1 (SIRT1) is involved in prostate cancer pathogenesis. However, the actual contribution is unclear as some reports propose a protective role while others suggest it is harmful. We provide evidence for a contextual role for SIRT1 in prostate cancer. Our data show that (i) mice orthotopically implanted with SIRT1-silenced LNCaP cells produced smaller tumors; (ii) SIRT1 suppression mimicked AR inhibitory effects in hormone responsive LNCaP cells; and (iii) caused significant reduction in gene signatures associated with E2F and MYC targets in AR-null PC-3 and E2F and mTORC1 signaling in castrate-resistant ARv7 positive 22Rv1 cells. Our findings further show increased nuclear SIRT1 (nSIRT1) protein under androgen-depleted relative to androgen-replete conditions in prostate cancer cell lines. Silencing SIRT1 resulted in decreased recruitment of AR to PSA enhancer selectively under androgen-deprivation conditions. Prostate cancer outcome data show that patients with higher levels of nSIRT1 progress to advanced disease relative to patients with low nSIRT1 levels. Collectively, we demonstrate that lowering SIRT1 levels potentially provides new avenues to effectively prevent prostate cancer recurrence.

Nexrutine® preserves muscle mass similar to exercise in prostate cancer mouse model

Muscle loss is a debilitating side effect to prostate cancer (PCa) experienced by nearly 60% of men. The purpose of this study was to test the hypothesis that Nexrutine® , a bark extract from the Phellodendrum amurense, can protect against prostate cancer induced muscle loss in a similar manner as exercise, using the transgenic adenocarcinoma of mouse prostate (TRAMP) model. Forty-five, 8- to 10-week old TRAMP mice were randomized to either control, Nexrutine® (600 mg/kg pelleted in chow) or exercise (voluntary wheel running). Mice were serially sacrificed at weeks 4, 8, 12, and 20, at which time either the left or right gastrocnemius muscle was harvested, weighted, and frozen. Proteolysis inducing factor (PIF), ubiquitin, and NF-κB concentrations were quantified using ELISA kits. Nexrutine® and exercise were equally able to protect TRAMP mice against PCa-induced muscle loss (P = 0.04). Both interventions decreased intramuscular PIF concentrations at 20 weeks compared to control (P < 0.05). A treatment effect was also observed when all time points were combined with exercise significantly lowering PIF concentrations (P < 0.01). Exercise significantly lowered intramuscular ubiquitin concentrations in weeks 4, 8, and 20 compared to control mice (P < 0.001). A treatment effect was also observed with exercise significantly lowering ubiquitin compared to control mice (P < 0.001). No significant changes were observed for NF-κB. The results of this investigation demonstrate that PCa-induced muscle loss can be attenuated with the herbal supplement Nexrutine® . This investigation provides preliminary evidence to support continued research into Nexrutine® as a potential exercise analog in protecting against muscle loss.

Abstract 5082: SIRT1 functions as a double-edged sword in prostate cancer

SIRT1 is a NAD+ dependent deacetylase known to regulate a plethora of biological processes through posttranslational regulation of proteins including those that function as tumor promoters and suppressors. In order to define the role of SIRT1 in prostate pathogenesis, we used 2 mouse models: (i) PTEN knockout (PTENKO) mouse model by pharmacological activation of SIRT1 with resveratrol (RES) a known activator of SIRT1, & (ii) orthotopic implantation model with genetic silencing of SIRT1 (SIRT1 shRNA). We also used genetic and pharmacologic inhibition of SIRT1 in cell culture models to understand the mechanism. We tested whether SIRT1 modulation is beneficial when targeted early (before the establishment of prostatic lesions) or late (after the establishment of prostatic lesions) in the PTENKO model. RES intervention was initiated in 4-5-week (early intervention) and 10-15-week-old (late intervention) PTENKO mice. Analyses of samples collected longitudinally during progression revealed that early intervention with RES reduced incidence of high-grade prostate intraepithelial neoplastic lesions (HGPIN) when given for 14 weeks with no significant difference at 7 or at 11 weeks. On the other hand, late intervention after the establishment of HGPIN lesions with RES had no beneficial effect. Importantly, longer treatment duration (28 weeks) resulted in significantly increased incidence of invasive prostate carcinoma. Furthermore, RES had no significant effect on the development of orthotopic prostate tumors following implantation of LNCaP cells in nude mice. In contrast, orthotopic implantation of SIRT1 stably silenced LNCaP cells showed significant impairment in tumor development. Immunohistochemical evaluation showed nuclear localization of SIRT1 in human prostate tumors and was associated with increased risk of biochemical recurrence. Mechanistic investigations revealed (i) suppression of AR signaling in hormone-sensitive LNCaP but not in castration-resistant 22Rv1 cells; (ii) RNAseq coupled with gene ontology enrichment analysis using SIRT1 silenced cells under conditions of androgen stimulation and inhibition identified genes involved in cell cycle checkpoint and senescence as top pathways affected by SIRT1 loss of function. In silicoanalysis shows that the identified SIRT1-regulated targets are associated with disease aggressiveness and poor disease-free survival. Taken together these data demonstrate that (i) SIRT1 plays a contextual role during prostate pathogenesis by functioning as tumor suppressor during early stage and as a tumor promoter during late stage; (ii) SIRT1 inhibition suppresses tumor development and (iii) RES is a better preventive than therapeutic agent. Therefore, our findings offer promising avenues to develop SIRT1-regulated pathways as novel therapeutic targets to inhibit prostate cancer recurrence. Supported by CPRIT Training Grant RP 170345 (SH) and CPRIT RP 150166 (APK)

Citation Format: Shih-Bo Huang, Dinesh Thapa, Roble G. Bedolla, Amanda R. Muñoz, Xiaoyu Yang, Paul Rivas, Robert L. Reddick, Hiroshi Miyamoto, Rita Ghosh, Addanki Pratap Kumar. SIRT1 functions as a double-edged sword in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5082.

Abstract P2-06-12: Oncogenic potential of Trefoil factor 3 in initiation of mammary carcinoma through suppression of p53 pathway

Background

Oncogenic transformation is a complex multistep process where normal cells acquire the hallmarks of cancer, leading to unrestrained outgrowth of malignant clones. Trefoil Factor 3 (TFF3) is a clinically validated and functionally potent oncogene in mammary carcinoma. Elevated TFF3 expression has been consistently observed in mammary carcinoma, being involved in cancer progression. The present study investigates the potential functional role and the underlying mechanisms of TFF3 in promoting oncogenic transformation early in the onset of mammary carcinoma.

Material and method

Immortalized human mammary epithelial cells (HMECs): HMEC-hTERT, MCF10A and MCF12A, with forced expression of TFF3, were used as in vitro models and in an orthotopic xenograft model to study the oncogenic roles of TFF3. Furthermore, microarray analysis, immunofluorescence, and ubiquitination and CHX chase assays were used to examine the involvement of p53 pathway in TFF3 mediated-oncogenic transformation.

Results

Immortalized HMECs with forced expression of TFF3 exhibited the capacity of anchorage independent growth in the soft agar colony formation assay, which is a hallmark of oncogenic transformation. The forced expression of TFF3 also enhanced 3D growth of the immortalized HMECs in matrigel. Furthermore, immortalized HMECs with forced expression of TFF3 gaverise to orthotopic xenograft tumors in nude mice, which are not observed in mice injected with immortalized HMECs. These observations suggest that TFF3 stimulates the oncogenic transformation of non-malignant immortalized HMECs. In addition, the forced expression of TFF3 promoted aberrant cell proliferation, resistance to apoptosis, and increased cell migration and invasion of the HMECs, all these being important hallmarks of cancer. Here, we showed that TFF3-mediated oncogenic transformation of the immortalized HMEC-hTERT cells is dependent on p53 signaling pathway suppression. Mechanistically, TFF3 downregulated NF-κB (p65)-mediated transcription of p53 through decreasing NF-κB (p65) expression and nuclear accumulation. TFF3 also decreased p53 protein levels through post-transcriptional regulation. The forced expression of TFF3 increased MDM2 expression, resulting in an increased ubiquitin-mediated proteasomal degradation of p53. Moreover, forced expression of TFF3 decreased the cleaved form of MDM2, which is responsible for stabilizing p53 protein. Concordantly, HMECs with forced expression of TFF3 exhibited shorter p53 protein half-life as compared to vector control HMECs .

Conclusion

In summary, our study highlights the oncogenic potential of TFF3 in the initiation of mammary carcinoma through the suppression of the p53 pathway.

Citation Format: Chen RM, Pandey V, Chong QY, Poh HM, Zhang MY, Kumar AP, Lobie PE. Oncogenic potential of Trefoil factor 3 in initiation of mammary carcinoma through suppression of p53 pathway [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-06-12.

Abstract P6-18-20: Targeting mitochondrial function for the treatment of triple negative breast cancer: Development of a small molecule inhibitor against mitochondrial STAT3

Background: Patients with Triple Negative Breast Cancer (TNBC) can benefit significantly from earlier diagnosis/prognosis, targeted therapy, and predictive biomarker panels for optimal therapy. However, currently there are no clinically accepted markers for the prognosis of TNBC and to predict its potential to metastasize. It is well documented that numerous cancer subtypes with increased mitochondrial oxidative phosphorylation in which enhanced mitochondrial activity is linked to aggressiveness. Also, there is greater awareness of metabolic heterogeneity within tumors, with some cells using glycolysis as their main energy source, whereas others use oxidative phosphorylation. Interestingly, TNBC has been shown to adopt increased mitochondrial biogenesis to "fuel" enhanced growth and aggressiveness. Signal Transducers and Activators of Transcription family 3 (STAT3) has been studied extensively as a transcription factor, however the finding that STAT3 also localizes to mitochondria has opened a new area to discover non-classical functions.

Methods: Targeting mitochondrial STAT3 functions challenge the current design of therapies that solely target STAT3 as a transcription factor and suggest the need for “design thinking,” to intervene the STAT3 pathway. With this in mind, we developed an in-house mitochondrial targeting - MitoTam. Data from in vitro cell-based assays, in vivo subcutaneous xenograft and patient-derived xenograft (PDX) models of TNBC will be reported.

Results:

Our data shows MitoTam robustly inhibited proliferation of TNBC cells at pharmacological doses and induced apoptosis. Mechanistically, we observed the MitoTam was able to target STAT3 leading to the downregulation of genes which is highly upregulated in most of the cancers. Furthermore, we show inhibition of STAT3 transcriptional activity hampers mitochondrial biogenesis, a prominent feature of cancer cell. Interestingly our in vivo and in vitro protein data showed the decreased phosphorylation of nuclear STAT3 and decreased mitochondria import of STAT3. We also found the decreased phosphorylation of STAT3 is associated with the interaction of GRIM-19 which is a cell death regulatory protein in complex1. Treatment of MitoTam was able to deplete the super complexes involved in OXPHOS and also in the regulation of mitochondrial transcription regulation. Our in vivo and PDX models show significant reduction of tumor size and tumor burden with treatment of MitoTam without effecting body mass. In addition we also found decrease in protein kinases associated with regulation of STAT3 for tumor survival. In addition, nuclear DNA encoded mitochondrial transcription factor A (TFAM), which enhances both transcription and replication of mitochondrial DNA is also shown to be downregulated with treatment, suggesting that MitoTam effectively inhibit TFAM binding to the mitochondrial DNA genes involved in OXPHOS regulation which was further validated by TFAM Chip-seq.

Conclusion: Our results places MitoTam is a promising candidate drug against TNBC and establish mitochondrial STAT3 as its molecular target.

Citation Format: Kanchi MM, Hirpara JL, Sachaphibulkij K, Tan TZ, Dietzel H, Lim LH, Huang RY-J, Pervaiz S, Neuzil J, Kumar AP. Targeting mitochondrial function for the treatment of triple negative breast cancer: Development of a small molecule inhibitor against mitochondrial STAT3 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-20.

Abstract P6-20-09: Pharmacological inhibition of TFF3 enhances chemo-sensitivity and overcomes acquired resistance in breast cancer

Background

Dose-dependent toxicity and acquired chemo-resistance are two major challenges in the use of doxorubicin in breast cancer treatment. Trefoil factor 3 (TFF3) is a secreted ligand that promotes breast cancer progression and predicts poor survival outcome of breast cancer patients. It has also been shown to confer resistance to anti-estrogens and trastuzumab in breast cancer. Here, the role of TFF3 in regulating the sensitivity and acquired resistance to doxorubicin in breast cancer was investigated.

Methods

MCF7, ZR-75-1 and BT474 breast cancer cell lines with siRNA-mediated depletion of TFF3, and doxorubicin-resistant MCF7 cells generated from the pulsatile exposure to doxorubicin, were used as in vitromodels. We have developed a novel non-toxic small molecule inhibitor of TFF3 (AMPC) that binds specifically to cysteine 57 residue of dimeric TFF3 and promotes its dissociation to monomers thereby, inhibiting its dimeric functions such as proliferation and apoptosis. Here, the effects of AMPC in enhancing doxorubicin sensitivity and overcoming acquired doxorubicin resistance in breast cancer cells were also explored.

Results

Consistent with siRNA-mediated depletion of TFF3, pharmacological inhibition of TFF3 by AMPC enhanced doxorubicin-mediated decrease in cell viability, foci formation and 3D growth of the breast cancer cells, suggesting that TFF3 inhibition increased the sensitivity of these cells to doxorubicin treatment. Notably, AMPC combined with doxorubicin in a synergistic manner, enabling doxorubicin dose reduction for the same inhibitory effect. Doxorubicin-induced AKT activation has been reported to antagonize the effects of doxorubicin and promote its resistance in breast cancer. Here, the inhibition of TFF3 by AMPC was shown to reduce AKT activation. Mechanistically, AMPC co-treatment suppressed doxorubicin-induced AKT activation thereby enhancing doxorubicin-induced apoptosis, with an overall up-regulation of pro-apoptotic and down-regulation of anti-apoptotic proteins, as compared to doxorubicin monotherapy. TFF3 also mediated the acquired doxorubicin resistance in MCF7 cells. Elevated expression of TFF3 was observed in the doxorubicin-resistant MCF7 cells as compared to the parental MCF7 cells, while the inhibition of TFF3 by AMPC completely abrogated the resistant phenotype of these cells as shown in the cell viability, foci formation and 3D growth assays. In concordance with the elevated levels of TFF3, doxorubicin-resistant MCF7 cells also exhibited increased activation of AKT with reduced susceptibility to doxorubicin-induced apoptosis as compared to the parental MCF7 cells. Consistently, this was reversed with AMPC co-treatment, which suppressed the elevated levels of activated AKT in the doxorubicin-resistant MCF7 cells, resulting in the re-sensitization of these resistant cells to doxorubicin-induced apoptosis. Similar to that in the parental cells, AMPC also exhibited a synergistic inhibitory effect with doxorubicin in the doxorubicin-resistant MCF7 cells.

Conclusion

The pharmacological inhibition of TFF3 with AMPC is a potential therapeutic approach to reduce the dose-dependent toxicity and to overcome the acquired resistance of doxorubicin in breast cancer.

Citation Format: Poh HM, Chong QY, Chen RM, Pandey V, Salundi B, Kumar AP, Lee SC, Lobie PE. Pharmacological inhibition of TFF3 enhances chemo-sensitivity and overcomes acquired resistance in breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-20-09.

TGF-β signal rewiring sustains epithelial-mesenchymal transition of circulating tumor cells in prostate cancer xenograft hosts

Activation of TGF-β signaling is known to promote epithelial-mesenchymal transition (EMT) for the development of metastatic castration-resistant prostate cancer (mCRPC). To determine whether targeting TGF-β signaling alone is sufficient to mitigate mCRPC, we used the CRISPR/Cas9 genome-editing approach to generate a dominant-negative mutation of the cognate receptor TGFBRII that attenuated TGF-β signaling in mCRPC cells. As a result, the delicate balance of oncogenic homeostasis is perturbed, profoundly uncoupling proliferative and metastatic potential of TGFBRII-edited tumor xenografts. This signaling disturbance triggered feedback rewiring by enhancing ERK signaling known to promote EMT-driven metastasis. Circulating tumor cells displaying upregulated EMT genes had elevated biophysical deformity and an increase in interactions with chaperone macrophages for facilitating metastatic extravasation. Treatment with an ERK inhibitor resulted in decreased aggressive features of CRPC cells in vitro. Therefore, combined targeting of TGF-β and its backup partner ERK represents an attractive strategy for treating mCRPC patients.

Abstract P4-08-03: DEAD-box RNA helicase DP103 as a novel regulator of Wnt/β-catenin signaling pathway and promotes cancer stem cell-like behavior in triple negative breast cancers

Despite recent advances in breast cancer therapeutics, mortality of metastatic triple negative breast cancer (TNBC) subtype remains high; due to their lack of hormone receptors expression for targeted therapy. Aberrant activation of Wnt/β-catenin signaling has been associated with breast cancers; where 40% of total breast cancers have elevated β-catenin levels with increased Wnt activity. Recently, we identified DEAD-box RNA helicase DP103 as a novel prognostic biomarker and metastasis-driving oncogene; highly expressed in TNBC subtype. Interestingly, we found high DP103 expression to be positively correlated with high β-catenin expression in clinical specimens (n=400). This led us to hypothesize a possible role of DP103 in modulating the Wnt/β-catenin pathway in TNBCs. Depletion of DP103 in metastatic TNBC cells decreases Wnt/β-catenin activity and expression of downstream Wnt target genes, while overexpression of DP103 increases Wnt activity. Depletion of DP103 also decreases phosphorylation of LRP6 and several important Wnt modulators required for downstream Wnt activation. Moreover, induction of Wnt/β-catenin signaling in Wnt responsive TNBC cells also significantly increased DP103 expression, indicating a possible positive feedback loop. Both canonical and non-canonical Wnt signaling is known to independently promote stem cell growth in mammospheres. Herein, we will also provide evidence on the role of DP103 in promoting breast cancer stem cell-like properties. Collectively, our data show a novel regulatory role of DP103 in the Wnt/β-catenin signaling pathway and in promoting breast cancer stem cell-like behavior, presenting itself as a potential drug target in TNBC patients.

Citation Format: Cai W, Cheong JK, Edison E, Banerjee A, Tan TZ, Gaboury L, Yousef EM, Thiery JP, Lobie PE, Virshup DM, Yap CT, Kumar AP. DEAD-box RNA helicase DP103 as a novel regulator of Wnt/β-catenin signaling pathway and promotes cancer stem cell-like behavior in triple negative breast cancers. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-08-03.

Gene Microarray Analyses of Daboia russelli russelli Daboiatoxin Treatment of THP-1 Human Macrophages Infected with Burkholderia pseudomallei

Burkholderia pseudomallei is the causative agent of melioidosis and represents a potential bioterrorism threat. In this study, the transcriptomic responses of B. pseudomallei infection of a human macrophage cell model were investigated using whole-genome microarrays. Gene expression profiles were compared between infected THP-1 human monocytic leukemia cells with or without treatment with Daboia russelli russelli daboiatoxin (DRRDbTx) or ceftazidime (antibiotic control). Microarray analyses of infected and treated cells revealed differential upregulation of various inflammatory genes such as interleukin-1 (IL-1), IL-6, tumor necrosis factor-alpha (TNF-α), cyclooxygenase (COX-2), vascular endothelial growth factor (VEGF), chemokine C-X-C motif ligand 4 (CXCL4), transcription factor p65 (NF-kB); and several genes involved in immune and stress responses, cell cycle, and lipid metabolism. Moreover, following DRR-DbTx treatment of infected cells, there was enhanced expression of the tolllike receptor 2 (TLR-2) mediated signaling pathway involved in recognition and initiation of acute inflammatory responses. Importantly, we observed that highly inflammatory cytokine gene responses were similar in infected cells exposed to DRR-DbTx or ceftazidime after 24 h. Additionally, there were increased transcripts associated with cell death by caspase activation that can promote host tissue injury. In summary, the transcriptional responses during B. pseudomallei infection of macrophages highlight a broad range of innate immune mechanisms that are activated within 24 h post-infection. These data provide insights into the transcriptomic kinetics following DRR-DbTx treatment of human macrophages infected with B. pseudomallei.

Palmatine inhibits growth and invasion in prostate cancer cell: Potential role for rpS6/NFκB/FLIP

Novel agents are desperately needed for improving the quality of life and 5-year survival to more than 30% for metastatic castrate-resistant prostate cancer. Previously we showed that Nexrutine, Phellodendron amurense bark extract, inhibits prostate tumor growth in vitro and in vivo. Subsequently using biochemical fractionation we identified butanol fraction contributes to the observed biological activities. We report here that palmatine, which is present in the butanol fraction, selectively inhibits growth of prostate cancer cells without significant effect on non-tumorigenic prostate epithelial cells. By screening receptor tyrosine kinases in a protein kinase array, we identified ribosomal protein S6, a downstream target of p70S6K and the Akt/mTOR signaling cascade as a potential target. We further show that palmatine treatment is associated with decreased activation of NFκB and its downstream target gene FLIP. These events led to inhibition of invasion. Similar results were obtained using parent extract Nexrutine (Nx) suggesting that palmatine either in the purified form or as one of the components in Nx is a potent cytotoxic agent with tumor invasion inhibitory properties. Synergistic inhibition of rpS6/NFκB/FLIP axis with palmatine may have therapeutic potential for the treatment of prostate cancer and possibly other malignancies with their constitutive activation. These data support a biological link between rpS6/NFκB/FLIP in mediating palmatine-induced inhibitory effects and warrants additional preclinical studies to test its therapeutic efficacy.

Abstract 3315: RON-mediated hijacking of AR signaling in androgen-independent prostate cancer

Despite significant progress in developing effective strategies for management of localized prostate cancer, the 5-year survival for metastatic castrate-resistant disease is less than 30%. Previous studies from our own and other laboratories showed the anti-tumorigenic potential of 2-Methoxyestradiol (2-ME2) in various tumor models. Although variety of mechanisms including anti-angiogenic, pro-apoptotic, cell cycle deregulation has been reported to contribute to 2-ME2-mediated biological effects, the precise mechanism is unclear. To explore the role of 2-ME2, we carried out gene expression array analysis and discovered Recepteur d’Origine Nantais (RON) as one of the most significantly down regulated gene in response to 2-ME2 treatment. Subsequently, RON was found to be significantly upregulated in advanced-stage PCA cell lines, which do not express androgen receptor (AR); and high-grade human prostate tumors. Stable silencing of RON in androgen independent, PTEN-/- PC3 cells showed noticeable changes in cell morphology, actin filament organization, as well as markers of epithelial-to-mesenchymal transition (EMT). In PTEN wild type DU145 cells, RON knockdown caused an increase in AR expression and promoter activity but decreased the transcriptional activation and expression of AR target genes such as PSA. In contrast, RON overexpression in androgen-responsive LNCAP cells leads to a suppression of the transcriptional activation of both AR and its downstream targets, including PSA. Furthermore, we found that RON silencing decreases expression and promoter activity of the anti-apoptotic protein FLICE-like inhibitory protein (FLIP) that is accompanied by the induction of apoptosis. In addition, intervention with 2-ME2 reduced tumor growth that is accompanied with decreased RON expression in the prostate in transgenic adenocarcinoma of mouse prostate (TRAMP) model. These observations implicate RON as a hijacker of AR signaling that contributes in part to PCA growth. Therefore, restoration of native AR signaling via RON targeting could possibly be exploited in combination with antiandrogenic therapy to prevent recurrence of castrate-resistant prostate cancer. Supported by CA135451 (APK).

Citation Format: Izhar Singh Batth, Peng Meng, Roble Bedolla, Robert E. Reddick, Addanki Pratap Kumar. RON-mediated hijacking of AR signaling in androgen-independent prostate cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3315. doi:10.1158/1538-7445.AM2014-3315

Abstract 4760: ER-β/Sp/NFκB/FLIP axis: Potential therapeutic target in prostate cancer

Emergence of hormone-refractory prostate cancer is fatal for lack of effective, durable systemic therapeutic strategies. Therefore, discovery of novel approaches and agents that can prevent development of therapeutically resistant disease and its progression is critical for successful management of prostate cancer (PCA). One of the reasons for the inability to implement such strategies is an incomplete understanding of molecular events associated with the development of therapeutically resistant disease. Previously, we reported the anti-tumorigenic potential of 2-methoxyestradiol (2-ME2) both in vitro and in vivo. We showed that (i) transcription factor Sp1 activates while Sp3 inhibits Sp1-mediated transactivation of anti-apoptotic gene FLIP in androgen independent prostate cancer PC-3 cells, and that (ii) 2-ME2-mediated tumor growth inhibitory effects were accompanied by transcriptional down-regulation of FLIP through 745 bp (-503/+242) sequence elements. In order to fully understand the underlying molecular mechanism of 2-ME2 induced down-regulation of FLIP, we generated exonuclease deletion constructs and performed transient transfection assays. These studies led to identification of -121/+242 sequence containing putative bindings sites for NFκB, CREB and AR in addition to Sp1 with maximal promoter activity in androgen responsive (LNCaP) and androgen independent (PC-3 and DU145) cells. Using ChIP assays, we also observed the enrichment of these factors to the endogenous FLIP promoter. Furthermore, androgen stimulation enhanced promoter activity and recruitment of Sp1, NFκB to the FLIP promoter region in LNCaP cells. Surprisingly, we found DHT but not R1881 decreased FLIP promoter activity in DU145 cells. Further molecular investigations indicated enhanced expression of AKR1C3 (aldo-keto reductase) that catalyzes the conversion of DHT to 3β-Adiol (a potent ligand for ER-β) in response to 2-ME2 treatment in DU145 cells. In addition, not only 3β-Adiol treatment reduced proliferation of prostate cancer cell significantly but co-transfection with ER-β reduced FLIP promoter activity. Taken together, these results implicate an important role for ER-β/Sp/NFκB/FLIP in mediating 2-ME2 induced tumor growth inhibitory effects. Supported by VA-Merit Award and CA 135451 (APK).

Citation Format: Huiyoung Yun, Jianping Xie, Izhar Singh Batth, Rong Li, Rita Ghosh, Addanki Pratap Kumar. ER-β/Sp/NFκB/FLIP axis: Potential therapeutic target in prostate cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4760. doi:10.1158/1538-7445.AM2014-4760

Tolerance of Phellodendron amurense bark extract (Nexrutine®) in patients with human prostate cancer

Phellodendron amurense bark extract (Nexrutine®) has shown a favorable effect on prostate cancer in vivo and in vitro. We evaluated its tolerance in patients undergoing surgery or radiation for prostate cancer. Patients received Nexrutine® orally (500 mg tid) either 1 to 2 months preoperatively or 1 to 2 months prior to and with radiation therapy. Common Terminology Criteria for Adverse Events were used to measure tolerance. In total, 21 patients (9 surgery and 12 radiation) underwent treatment. During the Nexrutine® alone component, there were two transient grade 3 toxicities (hypokalemia and urinary incontinence). There was no grade 4 toxicity. For the combined Nexrutine® and radiation component, no additional patients suffered a grade 3 toxicity. All the toxicities were transient. By the end of the neoadjuvant treatment, 81% of the patients had a decline in prostate-specific antigen. This is the first report of patients with prostate cancer being treated with P. amurense bark extract, and it was very well tolerated. Toxicities were minimal and self-limited. This compound can be safely used in further evaluation of a treatment effect on cancer.

Negative regulation of signal transducer and activator of transcription-3 signalling cascade by lupeol inhibits growth and induces apoptosis in hepatocellular carcinoma cells

Background:

Constitutive activation of signal transducer and activator of transcription signalling 3 (STAT3) has been linked with survival, proliferation and angiogenesis in a wide variety of malignancies including hepatocellular carcinoma (HCC).

Methods:

We evaluated the effect of lupeol on STAT3 signalling cascade and its regulated functional responses in HCC cells.

Results:

Lupeol suppressed constitutive activation of STAT3 phosphorylation at tyrosine 705 residue effectively in a dose- and time-dependent manner. The phosphorylation of Janus-activated kinases (JAKs) 1 and 2 and Src was also suppressed by lupeol. Pervanadate treatment reversed the downregulation of phospho-STAT3 induced by lupeol, thereby indicating the involvement of a phosphatase. Indeed, we observed that treatment with lupeol increased the protein and mRNA levels of SHP-2, and silencing of SHP-2 abolished the inhibitory effects of lupeol on STAT3 activation. Treatment with lupeol also downregulated the expression of diverse STAT3-regulated genes and decreased the binding of STAT3 to VEGF promoter. Moreover, the proliferation of various HCC cells was significantly suppressed by lupeol, being associated with substantial induction of apoptosis. Depletion of SHP-2 reversed the observed antiproliferative and pro-apoptotic effects of lupeol.

Conclusions:

Lupeol exhibited its potential anticancer effects in HCC through the downregulation of STAT3-induced pro-survival signalling cascade.

Single-cell analysis of circulating tumor cells identifies cumulative expression patterns of EMT-related genes in metastatic prostate cancer

BACKGROUND

Prostate tumors shed circulating tumor cells (CTCs) into the blood stream. Increased evidence shows that CTCs are often present in metastatic prostate cancer and can be alternative sources for disease profiling and prognostication. Here we postulate that CTCs expressing genes related to epithelial-mesenchymal transition (EMT) are strong predictors of metastatic prostate cancer.

METHODS

A microfiltration system was used to trap CTCs from peripheral blood based on size selection of large epithelial-like cells without CD45 leukocyte marker. These cells individually retrieved with a micromanipulator device were assessed for cell membrane physical properties using atomic force microscopy. Additionally, 38 CTCs from eight prostate cancer patients were used to determine expression profiles of 84 EMT-related and reference genes using a microfluidics-based PCR system.

RESULTS

Increased cell elasticity and membrane smoothness were found in CTCs compared to noncancerous cells, highlighting their potential invasiveness and mobility in the peripheral circulation. Despite heterogeneous expression patterns of individual CTCs, genes that promote mesenchymal transitioning into a more malignant state, including IGF1, IGF2, EGFR, FOXP3, and TGFB3, were commonly observed in these cells. An additional subset of EMT-related genes (e.g., PTPRN2, ALDH1, ESR2, and WNT5A) were expressed in CTCs of castration-resistant cancer, but less frequently in castration-sensitive cancer.

CONCLUSIONS

The study suggests that an incremental expression of EMT-related genes in CTCs is associated with metastatic castration-resistant cancer. Although CTCs represent a group of highly heterogeneous cells, their unique EMT-related gene signatures provide a new opportunity for personalized treatments with targeted inhibitors in advanced prostate cancer patients.

Abstract LB-101: Targeting pancreatic cancer stroma with Palmatine, a novel compound from herbal supplement

Pancreatic ductal adenocarcinoma is the fourth leading cause of cancer related deaths with 5-year survival rates less than 6%. Survival periods with gemcitabine in combination with various agents average over 6 months. Desmoplasia is a striking feature of pancreatic cancer. It is characterized by formation of dense stroma surrounding the tumor. This dense stroma serves as a therapeutic barrier for many chemotherapeutic drugs, in turn decreasing their efficacy. Pancreatic stellate cells (PSCs) have been reported to be involved in the observed desmoplastic reaction. Therefore targeting this stroma can be an alternate approach to pancreatic cancer. Previous studies from our laboratory showed that Nexrutine, a herbal supplement inhibits proliferation of multiple pancreatic cancer cells through modulation of Stat3/NFκB/Cox-2 signaling and reduced the number of animals developing fibrosis in vivo. To the best of our knowledge, the effect of Nexrutine or its active components on pancreatic stroma has not been studied. In this study we evaluated the effect of Nexrutine and Palmatine, an active component of Nexrutine, for its ability to target the stroma. Our studies show for the first time that Palmatine (i) inhibits proliferation of PSCs as well as the tumor cells; (ii) inhibits hedgehog signaling as evidenced by GLI expression and reporter activity; (iii) modulates expression and activity of downstream targets of GLI including Patched1, IKKB-ε and anti-apoptotic protein Survivin. Remarkably Palmatine treatment inhibits invasive ability of PSCs that is associated with reduced levels of COL1A1. Overall this is the first study reporting the ability of Palmatine to modulate Hh signaling and may have utility either alone or in conjunction with Gemcitabine for treatment of pancreatic ductal adenocarcinoma. Supported by NCCAM (AT 005513-01A1 and AT 007448l; APK).

Citation Format: Divya Chakravarthy, Jingjing Gong, Rosa F. Hwang, Addanki Pratap Kumar. Targeting pancreatic cancer stroma with Palmatine, a novel compound from herbal supplement. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-101. doi:10.1158/1538-7445.AM2013-LB-101

Abstract 5392: Metabolic profiling of castrate-resistant prostate cancer reveals novel role for bile acids in driving castration resistance

The 5-year survival for metastatic castrate-resistant prostate cancer patients is less than 30% despite significant progress in the understanding of prostate cancer biology and development of novel therapeutic agents. A major contributing factor for the observed low survival rate of patients with castrate resistant disease is the lack of knowledge regarding metabolic alterations and their underlying contributions during development of castrate-resistant phenotype. Studies conducted in our laboratory and others identified a potential role for 2-methoxyestradiol (2-ME2) to prevent prostate cancer development and progression through inhibition of the anti-apoptotic protein FLIP. The goal of the current study was to identify biochemical changes in response to castration and treatment with 2-ME2 in serum from transgenic adenocarcinoma of mouse prostate (TRAMP) mice using mass spectrometry based global profiling. We identified a total of 54 biochemicals of which 16 increased and 38 decreased in castrated animals compared to sham-castration. Treatment of sham-castrated animals with low and high doses of 2-ME2 altered 91 and 145 biochemicals respectively. On the other hand treatment of castrated animals modulated 89 and 106 biochemicals. Cumulative analysis of these data also identified alteration of 60 biochemicals associated with castration effect, 149 with treatment and 70 interactions between castration and treatment effects. Castration affected metabolites involved in variety of metabolic pathways including lipid, oxidative stress, energetics and bile acid. Given the data showing enhanced expression of FLIP in castrate-resistant prostate tumors and upregulation of bile acids in patients undergoing androgen deprivation therapy, we examined the activation of FLIP in prostate cancer cells in response to deoxycholic acid (DCA). Our data suggests that transcriptional activity of FLIP was higher in PC-3 cells treated with DCA. To the best of our knowledge, this is the first report demonstrating global metabolomic profiling of serum in response to castration and provide a framework for therapeutic targeting of bile acid metabolism. Supported by NIH CA 135451 (APK).

Citation Format: Divya Chakravarthy, Paul Rivas, Brian Keppler, Jianhua Ruan, Rita Ghosh, Addanki Pratap Kumar. Metabolic profiling of castrate-resistant prostate cancer reveals novel role for bile acids in driving castration resistance. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5392. doi:10.1158/1538-7445.AM2013-5392

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Deciphering the signaling networks underlying simvastatin-induced apoptosis in human cancer cells: evidence for non-canonical activation of RhoA and Rac1 GTPases

Although statins are known to inhibit proliferation and induce death in a number of cancer cell types, the mechanisms through which downregulation of the mevalonate (MVA) pathway activates death signaling remain poorly understood. Here we set out to unravel the signaling networks downstream of the MVA pathway that mediate the death-inducing activity of simvastatin. Consistent with previous reports, exogenously added geranylgeranylpyrophosphate, but not farnesylpyrophosphate, prevented simvastatin's growth-inhibitory effect, thereby suggesting the involvement of geranylgeranylated proteins such as Rho GTPases in the anticancer activity of simvastatin. Indeed, simvastatin treatment led to increased levels of unprenylated Ras homolog gene family, member A (RhoA), Ras-related C3 botulinum toxin substrate 1 (Rac1) and cell division cycle 42 (Cdc42). Intriguingly, instead of inhibiting the functions of Rho GTPases as was expected with loss of prenylation, simvastatin caused a paradoxical increase in the GTP-bound forms of RhoA, Rac1 and Cdc42. Furthermore, simvastatin disrupted the binding of Rho GTPases with the cytosolic inhibitor Rho GDIα, which provides a potential mechanism for GTP loading of the cytosolic Rho GTPases. We also show that the unprenylated RhoA- and Rac1-GTP retained at least part of their functional activities, as evidenced by the increase in intracellular superoxide production and JNK activation in response to simvastatin. Notably, blocking superoxide production attenuated JNK activation as well as cell death induced by simvastatin. Finally, we provide evidence for the involvement of the B-cell lymphoma protein 2 family, Bcl-2-interacting mediator (Bim), in a JNK-dependent manner, in the apoptosis-inducing activity of simvastatin. Taken together, our data highlight the critical role of non-canonical regulation of Rho GTPases and involvement of downstream superoxide-mediated activation of JNK pathway in the anticancer activity of simvastatin, which would have potential clinical implications.

Abstract 2582: 2-ME2-induced biological effects in prostate cancer: Role for miR127-3p/SET8

Prostate cancer is the second most common cause of death related to cancer in Western societies. 2-Methoxyestradiol (2-ME2), an endogenous metabolite of 17-α estradiol inhibits tumor cell proliferation in various cancer cells, including the prostate. Previous studies from our laboratory showed that 2-ME2 (i) inhibits proliferation of both androgen responsive and independent cells through induction of apoptosis involving G2/M check point block; (ii) prevents the development of prostate tumors in transgenic adenocarcinoma of mouse prostate (TRAMP) model. Although various molecular targets have been proposed, the mechanism of action behind its antiproliferative activity is still uncertain. Here we investigated the possible role for 2-ME2 induced antiproliferative activity by examining the altered regulation of microRNA (miRNAs). MicroRNA expression profiling identified miR127-3p as most significantly up regulated in response to 2-ME2 treatment in androgen independent (PC-3) cells. We have also identified histone methylase SET8 as a potential target of miR 127-3p. We have validated these data using Q-PCR. Further 2-ME2 treatment reduced binding of multiple transcription factors including Sp1, Sp3 and NFκB to the FLIP promoter as evidenced by transient expression assays, ChIP and gel-shift assays. Our findings indicate that 2-ME2 suppresses proliferation and induces apoptosis in prostate cancer cells possibly through miR127-3p/SET8 mediated regulation of FLIP. Supported by NIH CA 135451 (APK).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2582. doi:1538-7445.AM2012-2582

Abstract 2585: Resveratrol induces autophagy in prostate cancer cells and intervention suppresses the progression of PIN in animals

Resveratrol (3,4′-trihydroxystilbene), a natural product is present in significant concentrations in red wine, peanuts, walnuts etc. Emerging evidence indicates that resveratrol exerts antitumorigenic activity in various tumor models including prostate. Although multiple biological effects on proliferation, apoptosis and activation of SIRT1 have been demonstrated to be associated with resveratrol-induced activities, the precise mechanism associated with resveratrol-induced SIRT1 activation and cancer cell growth inhibition remains unclear. In addition, whether resveratrol intervention suppresses the development and progression of PIN (Prostatic Intraepithelial Neoplasia) is unknown. In this study, we examined the role of SIRT1 and the underlying mechanism involved in resveratrol-mediated biological effects. Our results show that although resveratrol significantly inhibited proliferation of multiple prostate cell lines including RWPE-1, C42B, PC3 and DU145 at higher concentrations (&gt; 50 µM); however, at lower concentrations (&lt; 25 µM), resveratrol prompted cell proliferation. Interestingly androgen responsive LNCaP cells exhibited resistance to resveratrol-mediated inhibition of cell proliferation. Under these experimental conditions, we also observed significant increase in autophagy without remarkable increase in apoptosis. Given the role of Akt/mTOR signaling pathway as a negative regulator of autophagy, we investigated whether resveratrol induce autophagy via modulation of Akt/mTOR signaling. Our data indicate that resveratrol-induced autophagy was associated with decreased levels of mTORC1 activity and increased SIRT1 expression. Knockdown of SIRT1 enhanced prostate cell proliferation and attenuated resveratrol-induced autophagy. Using prostate specific PTEN−/− mice, we found that dietary administration of resveratrol reduced the incidence of high-grade PIN lesions significantly. These findings implicated an important role for mTORC1/SIRT1 signaling axis in mediating resveratrol-induced upregulation of autophagy and inhibition of apoptosis. [Supported by NIH CA137578 (APK)]

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2585. doi:1538-7445.AM2012-2585

Abstract 351: 2-Methoxyestradiol targets RON kinase and FLIP to inhibit epithelial-mesenchymal transition in prostate cancer

Prostate Cancer (PCA) is the second leading cause of cancer-related deaths among men in the United States. Despite significant progress in our understanding of prostate biology, early detection and treatment, the five-year survival for hormone refractory metastatic prostate cancer (HRPCA) patients is less than 30%. Current therapies targeting PCA are not effective against the metastatic stage. 2-Methoxyestradiol (2-ME2) is a metabolic product of 17-β-estradiol and is found in trace amounts in the body; it has shown anti-tumorigenic properties in multiple cancer models. Previous studies from our lab have shown that 2-ME2 can induce apoptosis in PCA cells by blocking cell cycle progression, and also inhibits PCA growth and progression in TRAMP mice. However, the precise mechanism of action of 2-ME2 has not yet been elucidated. In order to classify the mechanism behind PCA inhibition by 2-ME2, we tested its effectiveness on an array containing genes associated with epithelial-mesenchymal transition (EMT). We identified Recepteur d'Origine Nantais (RON) as one of the most significantly downregulated genes in response to 2-ME2 treatment. RON has been shown to promote cell invasiveness, migration, survivability, and proliferation in many cancers such as breast, colon, lung, and pancreatic. However, very little is known about RON's signaling mechanism in PCA. We've found RON to be highly increased in advanced stage PCA cell lines. RON knockdown shows a concomitant decrease in the expression of FLICE-like inhibitory protein (FLIP). FLIP is an anti-apoptotic protein which prevents death receptor-induced apoptotic signaling. FLIP has been found to promote EMT as well as androgen-independent PCA growth. Stimulation with the RON ligand HGF yielded elevated expression of RON and FLIP in PCA cell lines while treatment with 2-ME2 caused downregulation. Immunoprecipitation experiments showed RON to be associated with the androgen-induced proliferation inhibitor (APRIN) in PCA cells. Our data suggest that RON/FLIP crosstalk plays a role in prostate cancer. Therefore, targeting RON/FLIP signaling could have potential therapeutic benefit for metastatic PCA. Supported by NIH CA 135451 (APK).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 351. doi:1538-7445.AM2012-351

Abstract B71: Phellodendron bioactive molecule (PBM): A potential natural agent for prevention of colon cancer

PBM is a yellow colored compound isolated from extracts of Phellodendron species. In the current study, PBM was subjected to understand the effect on colon cancer using human cancer cell lines. The activity was studied using three cancer cells having different degree if malignancy induction namely, SW-480, HT-29 and Caco-2 cells. The colon fibroblast (112CoN) cells, which are non cancerous were used to understand the toxicity of compound. The cell viability assay of PBM demonstrated both dose and time dependent activity in all the cells. This naturally occurring compound was found be effective after 24 h of treatment (IC50 value at 12 h was more than 75 µM) showing minimum IC50 against SW-480, which was 24, 16 and 5 µM at 24, 48 and 72 h, respectively. The IC50 was in the range of 42–50 µM for HT-29 cells and 18–53 µM for Caco-2 cells. Furthermore, the toxicity to normal cell was not significant indicating the non-toxicity compound at 100 µM in the model. Treatment at 10 µM has shown induction of aneuploidy (35±2% of cells) in SW-480 cells and treatment at 25 and 10 µM has increased accumulation of cells in G0/G1 phase. Protein expression results suggest that, PBM is capable of inhibiting cancer through inducing caspases dependant apoptosis in case of SW-480 cells. The inhibition was also found to be through inhibiting inflammatory proteins. Both the apoptosis and anti-inflammatory activity were higher at 48 and 72 h of treatment. Result of the current study provides an evidence for inhibition of colon cancer by PBM through multiple targets such as cell cycle arrest, apoptosis and inhibition of inflammation. In summary, PBM may be an ideal compound to be considered for in vivo studies to explore its application in colon cancer prevention. This project is based upon work supported by the USDA-CSREES # 2009-34402-19831 “Designing Foods for Health” through the Vegetable and Fruit Improvement Center.

Citation Information: Cancer Prev Res 2010;3(1 Suppl):B71.

Deformability study of breast cancer cells using microfluidics

Cell deformability is an important biomarker which can be used to distinguish between healthy and diseased cells. In this study, microfluidics is used to probe the biorheological behaviour of breast cancer cells in an attempt to develop a method to distinguish between non-malignant and malignant cells. A microfabricated fluidic channel design consisting of a straight channel and two reservoirs was used to study the biorheological behaviour of benign breast epithelial cells (MCF-10A) and non-metastatic tumor breast cells (MCF-7). Quantitative parameters such as entry time (time taken for the cell to squeeze into the microchannel) and transit velocity (speed of the cell flowing through the microchannel) were defined and measured from these studies. Our results demonstrated that a simple microfluidic device can be used to distinguish the difference in stiffness between benign and cancerous breast cells. This work lays the foundation for the development of potential microfluidic devices which can subsequently be used in the detection of cancer cells.

Malignancy arising in seminal vesicles in the transgenic adenocarcinoma of mouse prostate (TRAMP) model

BACKGROUND

Transgenic adenocarcinoma of mouse prostate (TRAMP) mice, derived by prostate specific expression of SV40 large T antigen using the rat probasin promoter, all develop prostate tumors akin to human prostate cancers. More recently, epithelial-stromal (ES) tumors resembling phyllodes tumors have been described in the seminal vesicles of TRAMP mice. We report malignancy arising in these ES tumors of the seminal vesicles in TRAMP mice.

METHODS

H&E stained sections from 28-week-old TRAMP mice autopsies were examined. Immunostains (cytokeratin, vimentin, desmin, and MIB-1) and electron microscopy were performed on selected blocks of the genitourinary system and metastatic tumor nodules.

RESULTS

The seminal vesicles frequently develop tumors containing broad papillae, with bland epithelium and a cellular spindled stroma just beneath the epithelium. The stromal cells have high nuclear to cytoplasmic ratio, frequent apoptotic cells and mitoses. In some cases, the stromal cells become large mass lesions that overgrow the prostate. The epithelium can also proliferate and become malignant. The tumors have high proliferation indices by MIB-1. Some metastatic tumors have characteristics similar to the seminal vesicle ES tumor.

CONCLUSIONS

Metastatic tumors in TRAMP mice show three patterns: (1) A definite adenocarcinoma pattern metastatic from the prostate; (2) poorly differentiated tumor without epithelial differentiation; (3) carcinosarcomatous pattern. The carcinosarcomatous pattern and some of the poorly differentiated tumors likely arise from seminal vesicle ES tumors.

Oxidative repression of NHE1 gene expression involves iron-mediated caspase activity

The mechanism of Na(+)/H(+) exchanger 1 (NHE1) gene repression upon exposure of cells to non-apoptotic concentrations of hydrogen peroxide (H(2)O(2)) was investigated. We show that continuous presence of H(2)O(2) was not required for inhibition of NHE1 promoter activity. However, the downregulation of NHE1 promoter activity and protein expression was abrogated by the presence of beta mercaptoethanol (betaME) and dithiothreitol. The pan-caspase inhibitor zVAD-fmk also blocked the effect of H(2)O(2) on NHE1 promoter activity and expression, but unlike betaME, caspase inhibition was ineffective in rescuing the early phase of NHE1 repression. Interestingly, the effect of caspase inhibition was observed only after 9 h of exposure to H(2)O(2) and completely restored NHE1 promoter activity by 18-24 h. Using tetrapeptide inhibitors of a variety of caspases and siRNA-mediated gene silencing, caspases 3 and 6 were identified as mediators of H(2)O(2)-induced NHE1 repression, independent of initiator/amplifier caspase activation. Furthermore, incubation of cells with the iron chelator, desferioxamine, not only blocked the activities of caspases 3 and 6, but also affected NHE1 promoter and protein expression in a manner similar to zVAD-fmk. These data show that a mild oxidative stress represses NHE1 promoter activity and expression via an early oxidation phase blocked by reducing agents, and a late phase requiring an iron-dependent increase in caspases 3 and 6 activities.

2-methoxyestradiol blocks cell-cycle progression at G(2)/M phase and inhibits growth of human prostate cancer cells

2-Methoxyestradiol (2-ME), an endogenous metabolite of 17beta-estradiol, is present in human blood and urine. Here we show for the first time that 2-ME significantly inhibited the growth of normal prostate epithelial cells and androgen-dependent LNCaP and androgen-independent DU145 prostate cancer cells. This growth inhibition was accompanied by a twofold increase in the G(2)/M population, with a concomitant decrease in the G(1) population, as shown by cell-cycle analysis. 2-ME treatment affected the cell-cycle progression of prostate cancer cells specifically by blocking cells in the G(2) phase. Immunoblot analysis of the key cell-cycle regulatory proteins in the G(2)/M phase showed a 14-fold increase in the expression of p21 and an eightfold increase in the expression of p34 cell division cycle 2 (cdc2). We also found an accumulation of phosphorylated cdc2 after 2-ME treatment. Furthermore, Wee 1 kinase was detectable after 2-ME treatment. 2-ME treatment also led to an increase in the activity of caspase-3, followed by apoptosis, as shown by terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate-biotin nick end-labeling and fluorescein isothiocyanate-poly(ADP-ribose) polymerase assay. Estrogen receptor levels did not change after treatment with 2-ME. Examination of the signaling pathways that mediate 2-ME-induced apoptosis showed reduction in the level of p53 expression and its DNA-binding activity. Given the fact that p53 mutations are common in patients with metastatic prostate cancer, our finding that 2-ME-mediated growth inhibition of human prostate cancer cells occurred in a p53-independent manner has considerable clinical significance. These findings, combined with the limited toxicity of 2-ME, may have significant implications for alternative treatment of advanced prostate cancer.

A negative regulatory element within the proximal promoter region of the rat ornithine decarboxylase gene

A putative Ets site with a core of GGAA located at nt -88 to -85 of the rat ornithine decarboxylase (ODC) gene was characterized by site-directed mutagenesis and transient expression assays. Mutation of this site, when in pODClux2m, which contains a cluster of four Sp1-binding sites, resulted in a 2.6-fold increase in basal promoter activity in untreated cells, whereas the ratio of activity in 12-O-tetradecanoylphorbol-13-acetate (TPA)-treated cells relative to the ratio in untreated cells (the induction ratio) remained largely unchanged. However, when the mutation was in pODClux168, which contains only a single Sp1-binding site (GC box V), it caused little alteration to either basal promoter activity or TPA induction ratio. A protein of 55-60 kDa was found specifically bound to this site, as shown by ultraviolet cross-linking assay. In competition assay and methylation interference assay, this protein was shown to occupy the GGAA core, although it showed no antigenic relation to c-Ets-1 in an supershift assay. We suggest that this protein binds specifically to the GGAA core and functions to inhibit activation of the ODC promoter by distal elements, including the upstream Sp1 sites.

Regulation of BRCA1 expression by the Rb-E2F pathway

Inheritance of a mutant allele of the breast cancer susceptibility gene BRCA1 confers increased risk of developing breast and ovarian cancers. Likewise, inheritance of a mutant allele of the retinoblastoma susceptibility gene (RB1) results in the development of retinoblastoma and/or osteosarcoma, and both alleles are often mutated or inactivated in sporadic forms of these and other cancers. We now demonstrate that the product of the RB1 gene, Rb, regulates the expression of the murine Brca1 and human BRCA1 genes through its ability to modulate E2F transcriptional activity. The Brca1 gene is identified as an in vivo target of E2F1 in a transgenic mouse model. The Brca1 promoter contains E2F DNA-binding sites that mediate transcriptional activation by E2F1 and repression by Rb. Moreover, ectopic expression of cyclin D1 and Cdk4 can stimulate the Brca1 promoter in an E2F-dependent manner, and this is inhibited by coexpression of the p16(INK4a) cyclin-dependent kinase inhibitor. The human BRCA1 promoter also contains a conserved E2F site and is similarly regulated by E2F1 and Rb. This functional link between the BRCA1 and Rb tumor suppressors may provide insight into the mechanism by which BRCA1 inactivation contributes to cancer development.

Enhanced Sp1 DNA-binding activity in murine keratinocyte cell lines and epidermal tumors

Altered regulation of ornithine decarboxylase (ODC) is frequently observed in epidermal tumors. We have shown that the transcription factor Sp1 is one of the regulators of ODC expression and that Sp3 antagonizes this Sp1-mediated activation of ODC expression. These results led us to examine the levels and binding activity of Sp1 and Sp3 in nuclear extracts prepared from cultured murine keratinocytes, transformed keratinocyte cell lines and epidermal tumors. Here we show that the Sp1 DNA-binding activity is higher in established keratinocyte cell line extracts than in primary keratinocyte extracts. Sp1 message levels and Sp1 DNA-binding activity was found to be low in 20-week papillomas and high in squamous cell carcinomas. These results suggest that increased levels of Sp1 and enhanced Sp1 DNA binding activity are correlated with epidermal tumor progression. Based on these results, we propose that increased Sp1 DNA binding may augment the proliferative capacity of tumor cells through overexpression of Sp1-responsive genes, possibly including ODC.

Serum responsive gene expression mediated by Sp1

We compared the Sp1 binding activity of Rat2 fibroblasts in nuclear extracts prepared from quiescent cells and cells stimulated with 20% serum. Increased DNA-binding activity was observed in extracts from serum-stimulated cells when an Sp1 oligonucleotide was used as radiolabeled probe in electrophoretic mobility shift assays. This increase in Sp1 DNA-binding activity is not due to changes in the amount of Sp1 in the nucleus as shown by immunoblot analysis. The transcriptional activity of a reporter construct containing six Sp1 sites upstream of a minimal adenovirus promoter or an Sp1-dependent promoter such as ornithine decarboxylase (ODC) containing Sp1 sites was enhanced following serum stimulation in transient transfection assays. Dephosphorylation of the nuclear extracts with potato acid phosphatase abolished the Sp1 DNA-binding activity, demonstrating a possible correlation between phosphorylation of Sp1 and DNA-binding activity. These results implicate a potential role for Sp1 in mediating signal transduction pathways in response to mitogenic signals.

Vibrational analysis of substituted benzonitriles. II. Transferability of force constants--the case of dicyanobenzenes

A zero-order normal coordinate analysis was made for p-, m- and o-dicyanobenzenes and their deuterated isomers by transferring the force constants from Part I. The observed and calculated frequencies agree with an average error of 18.7 cm-1, demonstrating the transferability of the force field obtained in Part 1. On the basis of the calculated potential energy distributions and eigen vectors, several assignments suggested by earlier workers have been revised.

Vibrational analysis of substituted benzonitriles. I. Vibrational spectra, normal coordinate analysis and transferability of force constants of monohalogenated benzonitriles

The Raman and Fourier--transform infrared spectra of p- and o-fluorobenzonitriles, p-, m- and o-chlorobenzonitriles and p-, m- and o-bromobenzonitriles were measured. Raman polarisation measurements were made wherever possible. A normal coordinate analysis was carried out for both the in-plane and out-of-plane vibrations of these molecules along with m-fluorobenzonitrile using a 71-parameter modified valence force field. An overlay least-squares-technique was employed to refine the force constants using 269 frequencies of nine molecules. The reliability of the force constants so obtained was tested by making a zero-order calculation for both in-plane and out-of-plane vibrations of p-, m- o-dicyanobenzenes and their deuterated isomers; 2-chloro, 6-fluorobenzonitrile, s-trichlorobenzonitrile, p- and m-methoxybenzonitriles and m-nitrobenzonitrile; and for the in-plane vibrations of p-, m-, o-aminobenzonitrile and 2-chloro, 5-aminobenzonitrile. Unambiguous vibrational assignments of all the fundamentals were made using the potential energy distributions and eigenvectors.

Vibrational analysis of substituted benzonitriles. IV. Transferability of force constants--the case of some aminobenzonitriles

A zero-order normal coordinate analysis was made for the n-plane vibrations of p-, m- and o-aminobenzonitrile and 2-chloro, 5-aminobenzonitrile by transferring the force constants from our earlier work. The observed and calculated frequencies agree with an average error of 19.3 cm-1. Unambiguous vibrational assignments of in-plane fundamentals of the four molecules have been made, and several assignments suggested by earlier workers have been revised.

Vibrational analysis of substituted benzonitriles. III. Transferability of force constants--the case of some halogeno-, methoxy- and nitro-benzonitriles

A zero-order normal coordinate analysis of both the in-plane and out-of-plane vibrations was made for 2-chloro, 6-fluorobenzonitrile, s-trichlorobenzonitrile, p- and m-methoxybenzonitriles and m-nitrobenzonitrile, transferring the force constants from our earlier work. The observed and calculated frequencies agree with an average error of 16.8 cm-1, demonstrating the transferability of the force constants obtained previously. On the basis of calculated potential energy distributions and eigenvectors, several assignments suggested by earlier workers have been revised.

Transcription factor Sp3 antagonizes activation of the ornithine decarboxylase promoter by Sp1

Ornithine decarboxylase (ODC) expression is important for proliferation and is elevated in many tumor cells. We previously showed that Sp1 is a major positive regulator of ODC transcription. In this paper we have investigated transcriptional regulation of rat ODC by the closely related factor Sp3. While over-expression of Sp1 caused a dramatic activation of the ODC promoter, over-expression of Sp3 caused little or no activation in either Drosophila SL2 cells (lacking endogenous Sp1 or Sp3) or in H35 rat hepatoma cells. Furthermore, co-transfection studies demonstrated that Sp3 abolished trans -activation of the ODC promoter by Sp1. DNase I footprint studies and electrophoretic mobility shift assays demonstrated that both recombinant Sp1 and Sp3 bind specifically to several sites within the ODC promoter also protected by nuclear extracts, including overlapping GC and CT motifs located between -116 and -104. This CT element is a site of negative ODC regulation. Mutation of either element reduced binding, but mutation of both sites was required to eliminate binding of either Sp1 or Sp3. These results demonstrate that ODC is positively regulated by Sp1 and negatively regulated by Sp3, suggesting that the ratio of these transcription factors may be an important determinant of ODC expression during development or transformation.

Disruption of transcription in vitro and gene expression in vivo by DNA adducts derived from a benzo[a]pyrene diol epoxide located in heterologous sequences

Previous studies indicated a high affinity of the transcription factor Sp1 for DNA adducts derived from benzo[a]pyrene diol epoxide (BPDE) in sequences that are not normal binding sites for Sp1. We tested for functional effects of this phenomenon in three systems in which transcription is Sp1-dependent. In an in vitro, Sp1-dependent transcription system addition of heterologous plasmid DNA containing BPDE adducts abolished production of a specific run-off transcript. This inhibition was not seen with unmodified plasmid DNA, and could be overcome by addition of purified Sp1 protein. In SL2 insect cells, high-level expression of an Sp1-dependent reporter gene, which was dependent on co-transfection of an Sp1 expression vector, was inhibited >95% by co-transfection of heterologous DNA containing BPDE adducts. This inhibition could be partially overcome by increasing the amount of the Sp1 expression vector in the transfections. In human C33A cells, expression of a transfected reporter gene driven by a GC box containing fragment of the human E2F1 promoter was enhanced by co-transfection of an Sp1 expression plasmid. Expression was inhibited 3-6-fold by co-transfection of heterologous DNA containing BPDE-DNA adducts. A similar inhibition was seen in human SAOS-2 cells, which lack functional p53 protein. These data are consistent with functionally significant sequestration of the Sp1 transcription factor by BPDE-DNA adducts in all three systems. Altered availability of transcription factors such as Sp1 in carcinogen-treated cells may disrupt patterns of gene expression.

Characterization of novel phorbol ester- and serum-responsive sequences of the rat ornithine decarboxylase gene promoter

Ornithine decarboxylase (ODC), the key regulatory enzyme in mammalian polyamine biosynthesis, is rapidly induced by mitogens and tumor promoters. We used transient expression assays and DNA-protein binding studies to examine the regulation of ODC promoter activity by phorbol esters and serum growth factors. A fragment of the ODC 5' flanking region (nt-1156 to +13) was sufficient to confer 12-O-tetradecanoylphorbol-13-acetate (TPA)-responsive expression to a luciferase reporter gene when transfected into H35 cells. However, induction by TPA was not observed in Rat2 fibroblasts, although refeeding of serum-starved Rat2 cells with fresh serum-containing medium rapidly induced a fivefold to sixfold increase in ODC promoter activity, maximal about 8 h after refeeding. Deletion analysis demonstrated that several sequences contributed to basal ODC promoter activity but that nt -92 to +13 was sufficient for induction by TPA or by serum. This sequence lacked canonical TPA-responsive elements, and an activator protein-1 (AP-1) consensus oligonucleotide failed to compete effectively for proteins binding to this region. Two of four protein complexes observed by gel-shift analysis of nt -92 to +13 were competitively inhibited by wild-type but not mutant oligonucleotides encompassing a variant cyclic AMP-response element (CRE) (ODC nt -50 to -42); however, a consensus CRE did not compete. Mutagenesis of this site demonstrated that it contributes to basal expression of the ODC promoter but not to TPA or serum responsiveness. Thus, we conclude that the proximal ODC promoter (nt -92 to +13) responds to TPA and serum stimulation in a cell-type-specific manner that is not mediated by canonical AP-1 elements.

Chest wall resection for Ewing's sarcoma of the rib: an unnecessary procedure. 1988. Updated in 1995

Approximately 10% of all cases of Ewing's sarcoma arise from a rib. Conventional management has included chest wall resection (3 or more ribs) and radiation therapy. These forms of therapy have led to complications such as scoliosis and local deformity. The addition of radiation therapy can result in damage to the lung and adjacent viscera and also potentiate pulmonary restrictive disease. Between 1971 and 1978, 9 patients were treated with surgery, radiation therapy, and combination chemotherapy (three- or four-drug regimen). Only 2 patients (22%) survive. Since 1979, 14 patients were entered into a new protocol consisting of sequential induction chemotherapy, followed by delayed surgical resection whenever feasible. Three patients had complete resection of their primary lesion at onset. Initially, 7 patients had either biopsy (N = 4) or incomplete chest wall resection N = 3). All 4 patients with biopsy only at diagnosis had excellent responses to induction chemotherapy, allowing delayed resection of the involved rib without chest wall resection. Overall, 12 of 14 patients (86%) treated since 1979 survive, with only 2 receiving radiation therapy for residual disease in the primary rib site.

Aspartate transcarbamoylase genes of Pseudomonas putida: requirement for an inactive dihydroorotase for assembly into the dodecameric holoenzyme

The nucleotide sequences of the genes encoding the enzyme aspartate transcarbamoylase (ATCase) from Pseudomonas putida have been determined. Our results confirm that the P. putida ATCase is a dodecameric protein composed of two types of polypeptide chains translated coordinately from overlapping genes. The P. putida ATCase does not possess dissociable regulatory and catalytic functions but instead apparently contains the regulatory nucleotide binding site within a unique N-terminal extension of the pyrB-encoded subunit. The first gene, pyrB, is 1,005 bp long and encodes the 334-amino-acid, 36.4-kDa catalytic subunit of the enzyme. The second gene is 1,275 bp long and encodes a 424-residue polypeptide which bears significant homology to dihydroorotase (DHOase) from other organisms. Despite the homology of the overlapping gene to known DHOases, this 44.2-kDa polypeptide is not considered to be the functional product of the pyrC gene in P. putida, as DHOase activity is distinct from the ATCase complex. Moreover, the 44.2-kDa polypeptide lacks specific histidyl residues thought to be critical for DHOase enzymatic function. The pyrC-like gene (henceforth designated pyrC') does not complement Escherichia coli pyrC auxotrophs, while the cloned pyrB gene does complement pyrB auxotrophs. The proposed function for the vestigial DHOase is to maintain ATCase activity by conserving the dodecameric assembly of the native enzyme. This unique assembly of six active pyrB polypeptides coupled with six inactive pyrC' polypeptides has not been seen previously for ATCase but is reminiscent of the fused trifunctional CAD enzyme of eukaryotes.

Regulation of rat ornithine decarboxylase promoter activity by binding of transcription factor Sp1

Ornithine decarboxylase (ODC) is the rate-limiting enzyme of polyamine biosynthesis. We investigated the transcriptional regulation of the rat ODC gene using transient expression assays. The 5'-flanking region (-1156 to +13) of the ODC gene was sufficient to mediate strong basal expression of a luciferase reporter. Sequences between -345 and -93 contributed to basal promoter activity. This region, containing five potential Sp1 binding sites, was analyzed by electrophoretic mobility shift assays. Three specific DNA-protein complexes were identified using H35 nuclear extracts and the -345/-93 ODC probe. Binding to all three was eliminated by competition with an oligonucleotide containing an Sp1 binding site, but not by a mutant Sp1 oligonucleotide. Preincubation with an antibody against Sp1 supershifted complexes associated with one or more of Sp1 binding sites 1-4 as well as with site 5. DNase I footprinting revealed two protected regions: PR-I (-92 to -130) and PR-II (-304 to -332). PR-I contains a putative binding site for Sp1 that was protected by recombinant Sp1 protein. Transfection studies in Schneider SL2 cells demonstrated that the ODC promoter is transactivated up to 350-fold by Sp1 and that this transactivation is dependent on the presence of Sp1 binding sites 1-4. Thus, although the ODC promoter binds multiple nuclear proteins, Sp1 or a related protein appears to be a critical determinant of ODC transcription, possibly through cooperative interactions between Sp1 and additional transcription factors.

Acute appendicitis in children with leukemia and other malignancies: still a diagnostic dilemma

Of 6,099 children treated for malignancy, 16 (ages 3.5 to 18 years) developed acute appendicitis between 1962 and 1989. Fourteen had leukemia (ALL 10, AML 4). One each had rhabdomyosarcoma and Ewing's sarcoma. Active malignancy at diagnosis was noted in 10, 4 of whom had severe neutropenia (absolute neutrophil count less than 500/mm3). Of all the leukemics (2,794/6,099), abdominal pain during induction was a frequent complaint. The incidence of appendicitis, however, was low (0.5%). Nine of the 16 patients presented classically, facilitating prompt diagnosis and treatment. Six diagnoses were delayed. Three of these patients presented atypically with vague, nonlocalized pain, abdominal distention, lack of abdominal guarding, fever, dehydration, diarrhea, and unusual symptoms such as upper gastrointestinal bleeding. In each of these 6 patients the appendix was ruptured. Delays led to complications and deaths. Three patients required perioperative transfusions to treat excessive bleeding and two patients with ruptured appendicitis developed wound abscesses. Two patients died; in one, ruptured appendix was diagnosed only at autopsy. The other patient died of uncontrolled sepsis. Typhlitis occurring during induction chemotherapy may present similarly and is the main differential diagnosis. Typhlitis will usually improve with medical treatment alone. Nausea and vomiting (13/16), right lower quadrant pain (13/16), guarding (14/16), tachycardia (12/16), fever (10/16), and rebound tenderness (10/16) were the most frequent signs and symptoms of appendicitis. Persistent localized abdominal pain and guarding, lack of improvement with medical treatment, clinical deterioration, and the development of a mass were our indications for laparotomy. Despite major improvements in therapy, there is still a 37.5% error rate in our ability to accurately diagnose appendicitis in pediatric cancer patients.

Wilms' tumor: reduced-dose radiotherapy in advanced-stage Wilms' tumor with favorable histology

Fifty-two children with favorable histology Wilms' tumor who had residual abdominal disease (Surgical Stages III and IV) were treated from 1979 to 1988 on a protocol designed to assess the effectiveness of reduced radiation doses. All patients received three-agent chemotherapy, beginning within 1 week after surgery. To permit assessment of disease response to initial chemotherapy, radiation therapy was delayed for a median of 28 days after surgery (range, 14-71 days). Total doses of abdominal radiation were limited to 12 Gy, given as 150 cGy daily fractions; 18 patients with Stage IV disease received 12 Gy bilateral pulmonary irradiation. Two year disease-free survival was 85% and 71% for Stage III and IV, respectively (p = .24). Abdominal relapses occurred in 3 cases (5.7%). The interval between surgery and initiation of irradiation was not related to disease-free survival. Of several patient and disease-related factors analyzed, only patient age was related to outcome. Disease-free survival was 100% at 3 years for children under the age of 3 versus 78% for children greater than age 3 (p = .05). Reduced-dose abdominal radiotherapy in conjunction with multi-agent chemotherapy and surgery provided excellent disease control with minimal toxicity in advanced-stage, favorable histology Wilms' tumor.

Malignant melanoma in children: its management and prognosis

Malignant melanoma is rare in children, representing 1% to 3% of all pediatric malignancies. Thirty-three children with malignant melanoma were treated at St Jude Children's Research Hospital from 1967 to 1988. Their ages ranged from 1 day to 20 years (median, 12 years); 23 were boys and 10 were girls; and 5 of the 33 (15%) were black. Four of the 33 children had been treated for a previous malignancy. In 3, melanoma arose within a bathing trunk nevus. The extremity was the most common site (13), followed by the trunk (9), head and neck (7), and perineum (1). In 3 patients the primary site could not be determined. Upon initial presentation to St Jude Hospital, 17 patients had localized disease (stage I), 10 had regional node involvement (stage II), and the remaining 6 patients had disseminated disease (stage III). Using both Clark's level and Breslow's thickness as indicators, the incidence, initial stage, prognosis, and survival were compared. By Clark's level, 7 patients, (6 of whom were stage I) were level II or III, and 22 patients were level IV or V. Though 16 of 22 level IV and V patients were initially stage I, 10 patients eventually developed progressive disease. Similar observations were noted when using Breslow's thickness to evaluate the primary. In 5 of 27 evaluable patients, Breslow's depth of invasion was less than 1.5 mm. All 5 of these patients were diagnosed with stage I disease and have not shown progressive disease.

Adjuvant chemotherapy for osteosarcoma of the extremity. Long-term results of two consecutive prospective protocol studies

Seventy-six patients with classic high-grade osteosarcoma of an extremity received adjuvant chemotherapy by two protocols, initiated in 1972 and 1977, respectively, after appropriate amputations. Chemotherapy consisted of high-dose methotrexate, doxorubicin, and cyclophosphamide. Dose intensity of high-dose methotrexate and doxorubicin was greater for the patients treated with the protocol initiated in 1977. The proportion of long-term disease-free survivors on the two protocols are 46% and 56%. A better outcome (P = 0.042) was seen for the latter group, which received more intensive chemotherapy. Overall, metastases developed in 35 patients; in 19 who were receiving chemotherapy and in 16 after chemotherapy. The outcome for these two protocols, compared with two control groups that were given no chemotherapy or ineffective chemotherapy (biweekly vincristine and cyclophosphamide), confirms the results of controlled studies that showed an advantage of adjuvant chemotherapy after amputation for osteosarcoma.