Griseofulvin Radiosensitizes Non-Small Cell Lung Cancer Cells and Activates cGAS

Extra copies of centrosomes are frequently observed in cancer cells. To survive and proliferate, cancer cells have developed strategies to cluster extra-centrosomes to form bipolar mitotic spindles. The aim of this study was to investigate whether centrosome clustering (CC) inhibition (CCi) would preferentially radiosensitize non-small cell lung cancer (NSCLC). Griseofulvin (GF; FDA-approved treatment) inhibits CC, and combined with radiation treatment (RT), resulted in a significant increase in the number of NSCLC cells with multipolar spindles, and decreased cell viability and colony formation ability in vitro. In vivo, GF treatment was well tolerated by mice, and the combined therapy of GF and radiation treatment resulted in a significant tumor growth delay. Both GF and radiation treatment also induced the generation of micronuclei (MN) in vitro and in vivo and activated cyclic GMP-AMP synthase (cGAS) in NSCLC cells. A significant increase in downstream cGAS-STING pathway activation was seen after combination treatment in A549 radioresistant cells that was dependent on cGAS. In conclusion, GF increased radiation treatment efficacy in lung cancer preclinical models in vitro and in vivo. This effect may be associated with the generation of MN and the activation of cGAS. These data suggest that the combination therapy of CCi, radiation treatment, and immunotherapy could be a promising strategy to treat NSCLC.

Effectiveness of Decision Aid in Men with Localized Prostate Cancer: a Multicenter Randomized Controlled Trial at Tertiary Referral Hospitals in an Asia Pacific Country

There are several treatment options for localized prostate cancer with very similar outcome but vary in terms of technique and side effect profiles and risks. Considering the potential difficulty in choosing the best treatment, a patient decision aid (PDA) is used to help patients in their decision-making process. However, the use and applicability of PDA in a country in Asia Pacific region like Malaysia is still unknown. This study aims to evaluate the effectiveness of a PDA modified to the local context in improving patients' knowledge, decisional conflict, and preparation for decision making among men with localized prostate cancer. Sixty patients with localized prostate cancer were randomly assigned to control and intervention groups. A self-administered questionnaire, which evaluate the knowledge on prostate cancer (23 items), decisional conflict (10 items) and preparation for decision-making (10 items), was given to all participants at pre- and post-intervention. Data were analyzed using independent T test and paired T test. The intervention group showed significant improvement in knowledge (p = 0.02) and decisional conflict (p = 0.01) from baseline. However, when compared between the control and intervention groups, there were no significant differences at baseline and post-intervention on knowledge, decisional conflict and preparation for decision-making. A PDA on treatment options of localized prostate cancer modified to the local context in an Asia Pacific country improved patients' knowledge and decisional conflict but did not have significant impact on the preparation for decision-making. The study was also registered under the Australian New Zealand Clinical Trials Registry (ANZCTR), ACTRN12614000668606 registered on 25/06/2014.

Abstract B11: O-GlcNAcylation is required for mutant KRAS-induced lung tumorigenesis

Mutant KRAS drives glycolytic flux in lung cancer, potentially impacting aberrant protein glycosylation. Recent evidence suggests aberrant KRAS drives flux of glucose into the hexosamine biosynthetic pathway (HBP). HBP is required for various glycosylation processes, such as protein N- or O-glycosylation and glycolipid synthesis. However, its function during tumorigenesis is poorly understood. One contributor and proposed target of KRAS-driven cancers is a developmentally conserved epithelial plasticity program called epithelial-mesenchymal transition (EMT). Here we showed in novel autochthonous mouse models that EMT accelerated KrasG12D lung tumorigenesis by upregulating expression of key enzymes of the HBP pathway. We demonstrated that HBP was required for suppressing KrasG12D-induced senescence, and targeting HBP significantly delayed KrasG12D lung tumorigenesis. To explore the mechanism, we investigated protein glycosylation downstream of HBP and found elevated levels of O-linked β-N-acetylglucosamine (O-GlcNAcylation) post-translational modification on intracellular proteins. O-GlcNAcylation suppressed KrasG12D oncogene-induced senescence (OIS) and accelerated lung tumorigenesis. Conversely, loss of O-GlcNAcylation delayed lung tumorigenesis. O-GlcNAcylation of proteins SNAI1 and c-MYC correlated with the EMT-HBP axis and accelerated lung tumorigenesis. Our results demonstrated for the first time that O-GlcNAcylation was sufficient and required to accelerate KrasG12D lung tumorigenesis in vivo, which was reinforced by epithelial plasticity programs.

Citation Format: Takumi Shiraishi, Phuoc T. Tran, Reem Malek, Audrey Lafargue, Mustafa Barbhuiya, Xing Wang, Brian Simons, Matthew Ballew, Katriana Nugent, Jennifer Groves, Russell Williams, Hailun Wang, James Verdone, Gokben Yildirir, Roger Henry, Bin Zhang, John Wong, Ken Wang, Barry Nelkin, Kenneth Pienta, Dean Felsher, Natasha Zachara, Kekoa Taparra. O-GlcNAcylation is required for mutant KRAS-induced lung tumorigenesis [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr B11.

Relationship between HbA1c and Lipid Profile Seen in Bangladeshi Type 2 Diabetes Mellitus Patients Attending BIRDEM Hospital: A Cross-Sectional Study

Diabetes mellitus is one of the leading non-communicable diseases all over the world including Bangladesh. Diabetes is characterized by chronic hyperglycemia and disturbances of carbohydrate, lipid and protein metabolism. Glycated hemoglobin (HbA1c) level of ≥6.5% has been included as a criterion for diagnosis of diabetes. Impaired lipid profile is commonly present in type 2 diabetes. Aim of the study was to investigate the association between serum lipid profile and blood glucose. And hypothesizing that early detection of lipid abnormalities and treatment can minimize the risk for atherogenic cardiovascular disorder and cerebrovascular calamity in patients with type 2 diabetes mellitus (T2DM). This observational cross sectional study was carried out in the department of Biochemistry, Bangladesh Institute of Research & Rehabilitation in Diabetes, Endocrine and Metabolic Disorders (BIRDEM) hospital, Dhaka, Bangladesh from January 2016 to June 2016. A total 105 patients with T2DM of age within the range of 30-45 years were selected for the purpose. Fasting blood glucose (FBG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglyceride (TG) and glycated haemoglobin (HbA1c) levels were evaluated. Test of significance was calculated by unpaired Student's 't' test. Correlation studies (Pearson's correlation) were performed between glycated haemoglobin (HbA1c) and serum lipid profile. Significance was set at p<0.05. Significantly higher mean serum levels of TC, TG and LDL-C and significantly lower mean serum levels of HDL-C were noted in patients with diabetes. Significant correlations were observed between HbA1c value and serum levels of TC, TG and HDL-C (p<0.05) but no significant correlation of HbA1c value with LDL-C in-diabetes patient. The study concluded that HbA1c value correlate well with lipid profile in-diabetes patients. So, HbA1c can be used as a predictor of dyslipidemia in type 2 diabetes.

O-GlcNAcylation is required for mutant KRAS-induced lung tumorigenesis

Mutant KRAS drives glycolytic flux in lung cancer, potentially impacting aberrant protein glycosylation. Recent evidence suggests aberrant KRAS drives flux of glucose into the hexosamine biosynthetic pathway (HBP). HBP is required for various glycosylation processes, such as protein N- or O-glycosylation and glycolipid synthesis. However, its function during tumorigenesis is poorly understood. One contributor and proposed target of KRAS-driven cancers is a developmentally conserved epithelial plasticity program called epithelial-mesenchymal transition (EMT). Here we showed in novel autochthonous mouse models that EMT accelerated KrasG12D lung tumorigenesis by upregulating expression of key enzymes of the HBP pathway. We demonstrated that HBP was required for suppressing KrasG12D-induced senescence, and targeting HBP significantly delayed KrasG12D lung tumorigenesis. To explore the mechanism, we investigated protein glycosylation downstream of HBP and found elevated levels of O-linked β-N-acetylglucosamine (O-GlcNAcylation) posttranslational modification on intracellular proteins. O-GlcNAcylation suppressed KrasG12D oncogene-induced senescence (OIS) and accelerated lung tumorigenesis. Conversely, loss of O-GlcNAcylation delayed lung tumorigenesis. O-GlcNAcylation of proteins SNAI1 and c-MYC correlated with the EMT-HBP axis and accelerated lung tumorigenesis. Our results demonstrated that O-GlcNAcylation was sufficient and required to accelerate KrasG12D lung tumorigenesis in vivo, which was reinforced by epithelial plasticity programs.

Ganetespib radiosensitization for liver cancer therapy

Therapies for liver cancer particularly those including radiation are still inadequate. Inhibiting the stress response machinery is an appealing anti-cancer and radiosensitizing therapeutic strategy. Heat-shock-protein-90 (HSP90) is a molecular chaperone that is a prominent effector of the stress response machinery and is overexpressed in liver cancer cells. HSP90 client proteins include critical components of pathways implicated in liver cancer cell survival and radioresistance. The effects of a novel non-geldanamycin HSP90 inhibitor, ganetespib, combined with radiation were examined on 3 liver cancer cell lines, Hep3b, HepG2 and HUH7, using in vitro assays for clonogenic survival, apoptosis, cell cycle distribution, γH2AX foci kinetics and client protein expression in pathways important for liver cancer survival and radioresistance. We then evaluated tumor growth delay and effects of the combined ganetespib-radiation treatment on tumor cell proliferation in a HepG2 hind-flank tumor graft model. Nanomolar levels of ganetespib alone exhibited liver cancer cell anti-cancer activity in vitro as shown by decreased clonogenic survival that was associated with increased apoptotic cell death, prominent G2-M arrest and marked changes in PI3K/AKT/mTOR and RAS/MAPK client protein activity. Ganetespib caused a supra-additive radiosensitization in all liver cancer cell lines at low nanomolar doses with enhancement ratios between 1.33–1.78. These results were confirmed in vivo, where the ganetespib-radiation combination therapy produced supra-additive tumor growth delay compared with either therapy by itself in HepG2 tumor grafts. Our data suggest that combined ganetespib-radiation therapy exhibits promising activity against liver cancer cells, which should be investigated in clinical studies.

TWIST1-WDR5-Hottip Regulates Hoxa9 Chromatin to Facilitate Prostate Cancer Metastasis

TWIST1 is a transcription factor critical for development that can promote prostate cancer metastasis. During embryonic development, TWIST1 and HOXA9 are coexpressed in mouse prostate and then silenced postnatally. Here we report that TWIST1 and HOXA9 coexpression are reactivated in mouse and human primary prostate tumors and are further enriched in human metastases, correlating with survival. TWIST1 formed a complex with WDR5 and the lncRNA Hottip/HOTTIP, members of the MLL/COMPASS-like H3K4 methylases, which regulate chromatin in the Hox/HOX cluster during development. TWIST1 overexpression led to coenrichment of TWIST1 and WDR5 as well as increased H3K4me3 chromatin at the Hoxa9/HOXA9 promoter, which was dependent on WDR5. Expression of WDR5 and Hottip/HOTTIP was also required for TWIST1-induced upregulation of HOXA9 and aggressive cellular phenotypes such as invasion and migration. Pharmacologic inhibition of HOXA9 prevented TWIST1-induced aggressive prostate cancer cellular phenotypes in vitro and metastasis in vivo This study demonstrates a novel mechanism by which TWIST1 regulates chromatin and gene expression by cooperating with the COMPASS-like complex to increase H3K4 trimethylation at target gene promoters. Our findings highlight a TWIST1-HOXA9 embryonic prostate developmental program that is reactivated during prostate cancer metastasis and is therapeutically targetable. Cancer Res; 77(12); 3181-93. ©2017 AACR.

Therapeutic Targeting of Epithelial Plasticity Programs: Focus on the Epithelial-Mesenchymal Transition

Mounting data points to epithelial plasticity programs such as the epithelial-mesenchymal transition (EMT) as clinically relevant therapeutic targets for the treatment of malignant tumors. In addition to the widely realized role of EMT in increasing cancer cell invasiveness during cancer metastasis, the EMT has also been implicated in allowing cancer cells to avoid tumor suppressor pathways during early tumorigenesis. In addition, data linking EMT to innate and acquired treatment resistance further points towards the desire to develop pharmacological therapies to target epithelial plasticity in cancer. In this review we organized our discussion on pathways and agents that can be used to target the EMT in cancer into 3 groups: (1) extracellular inducers of EMT, (2) the transcription factors that orchestrate the EMT transcriptome, and (3) the downstream effectors of EMT. We highlight only briefly specific canonical pathways known to be involved in EMT, such as the signal transduction pathways TGFβ, EFGR, and Axl-Gas6. We emphasize in more detail pathways that we believe are emerging novel pathways and therapeutic targets such as epigenetic therapies, glycosylation pathways, and immunotherapy. The heterogeneity of tumors and the dynamic nature of epithelial plasticity in cancer cells make it likely that targeting only 1 EMT-related process will be unsuccessful or only transiently successful. We suggest that with greater understanding of epithelial plasticity regulation, such as with the EMT, a more systematic targeting of multiple EMT regulatory networks will be the best path forward to improve cancer outcomes.

RK-33 Radiosensitizes Prostate Cancer Cells by Blocking the RNA Helicase DDX3

Despite advances in diagnosis and treatment, prostate cancer is the most prevalent cancer in males and the second highest cause of cancer-related mortality. We identified an RNA helicase gene, DDX3 (DDX3X), which is overexpressed in prostate cancers, and whose expression is directly correlated with high Gleason scores. Knockdown of DDX3 in the aggressive prostate cancer cell lines DU145 and 22Rv1 resulted in significantly reduced clonogenicity. To target DDX3, we rationally designed a small molecule, RK-33, which docks into the ATP-binding domain of DDX3. Functional studies indicated that RK-33 preferentially bound to DDX3 and perturbed its activity. RK-33 treatment of prostate cancer cell lines DU145, 22Rv1, and LNCaP (which have high DDX3 levels) decreased proliferation and induced a G₁ phase cell-cycle arrest. Conversely, the low DDX3-expressing cell line, PC3, exhibited few changes following RK-33 treatment. Importantly, combination studies using RK-33 and radiation exhibited synergistic effects both in vitro and in a xenograft model of prostate cancer demonstrating the role of RK-33 as a radiosensitizer. Taken together, these results indicate that blocking DDX3 by RK-33 in combination with radiation treatment is a viable option for treating locally advanced prostate cancer. Cancer Res; 76(21); 6340-50. ©2016 AACR.

Evaluation of HIV testing recommendations in specialty guidelines for the management of HIV indicator conditions

Objectives

European guidelines recommend HIV testing for individuals presenting with indicator conditions (ICs) including AIDS‐defining conditions (ADCs). The extent to which non‐HIV specialty guidelines recommend HIV testing in ICs and ADCs is unknown. Our aim was to pilot a methodology in the UK to review specialty guidelines and ascertain if HIV was discussed and testing recommended.

Methods

UK and European HIV testing guidelines were reviewed to produce a list of 25 ADCs and 49 ICs. UK guidelines for these conditions were identified from searches of the websites of specialist societies, the National Institute of Clinical Excellence (NICE) website, the NICE Clinical Knowledge Summaries (CKS) website, the Scottish Intercollegiate Guidance Network (SIGN) website and the British Medical Journal Best Practice database and from Google searches.

Results

We identified guidelines for 12 of 25 ADCs (48%) and 36 of 49 (73%) ICs. In total, 78 guidelines were reviewed (range 0–13 per condition). HIV testing was recommended in six of 17 ADC guidelines (35%) and 24 of 61 IC guidelines (39%). At least one guideline recommended HIV testing for six of 25 ADCs (24%) and 16 of 49 ICs (33%). There was no association between recommendation to test and publication year (P = 0.62).

Conclusions

The majority of guidelines for ICs do not recommend testing. Clinicians managing ICs may be unaware of recommendations produced by HIV societies or the prevalence of undiagnosed HIV infection among these patients. We are piloting methods to engage with guideline development groups to ensure that patients diagnosed with ICs/ADCs are tested for HIV. We then plan to apply our methodology in other European settings as part of the Optimising Testing and Linkage to Care for HIV across Europe (OptTEST) project.

Abstract 1054: SNAI1 regulates the hexosamine biosynthetic pathway to promote tumorigenesis and oncogene-induced senescence escape in lung cancer

Lung cancer is the deadliest and most common malignancy worldwide. Tumor invasion and metastasis influence the dismal 16% overall 5-year survival. Evidence suggests malignancies commandeer epithelial plasticity programs like the epithelial-mesenchymal transition (EMT) to promote tumorigenesis, tumor progression, and metastasis. Furthermore, EMT has recently been linked to alterations in cancer metabolism, which can engender adaptation to environmental stress while supporting the macromolecular demand of rapid proliferation. Thus it is important to better understand the emerging roles of EMT in regulating cancer metabolism. SNAI1 is a master EMT regulator and is aberrantly overexpressed in many cancers including lung cancer. To investigate the role of SNAI1 in tumorigenesis, we created a novel inducible autochthonous mouse model. Our model reveals SNAI1 overexpressing mutant Kras mice generate identifiable tumors twice as fast (median = 14 weeks) as mice overexpressing mutant Kras alone (median = 30 weeks). To identify possible mechanisms of SNAI1-accelerated tumorigenesis, we used mRNA expression profiling. We identified significantly altered gene signatures related to metabolic reprogramming. Specifically, SNAI1 upregulates the hexosamine biosynthetic pathway (HBP) in mutant Kras-driven mouse lung tumors. SNAI1 elevates protein and mRNA of the rate limiting step (GFPT2) and final step (UAP1) of this pathway. This SNAI1-driven promotion of the HBP was recapitulated in vitro using human non-small cell lung cancer (NSCLC) SNAI1 isogenic cell lines. NSCLC mRNA expression data from The Cancer Genome Atlas (TCGA) also showed SNAI1 expression in patient tumor samples correlate with a significant tendency towards co-expression with HBP genes (Fisher's exact test, p&lt;0.05). Functionally, the final metabolite generated by the HBP, UDP-GlcNAc, is an essential nucleotide sugar found in a plethora of N- and O-linked glycosylations, regulating protein stability and activity. Here we show SNAI1 promotes flux through the HBP to promote increased total levels of O-GlcNAcylated proteins in lung tumors in vivo. In so doing, modulation of the HBP and specific glycosylations may impact cell death and senescence, suggesting a novel targetable EMT-HBP axis. Numerous oncogenes, including c-Myc and SNAI1 itself, are known to be stabilized by O-GlcNAcylation. This link is becoming of increasing importance in cancer biology, as half of the body of literature on O-GlcNAcylation and cancer has been published in the past three years. Together, our data suggest heightened protein O-GlcNAcylation, mediated by SNAI1 and the HBP, serves as a novel means by which EMT contributes to mutant Kras-induced lung tumorigenesis and tumor progression.

Citation Format: Kekoa Taparra, Hailun Wang, Katriana Nugent, Reem Malek, Jen Groves, Gokben Yildirir, Brian Simons, Dean Felsher, Natasha Zachara, Phuoc Tran. SNAI1 regulates the hexosamine biosynthetic pathway to promote tumorigenesis and oncogene-induced senescence escape in lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1054.

Bioluminescence Tomography-Guided Radiation Therapy for Preclinical Research

PURPOSE

In preclinical radiation research, it is challenging to localize soft tissue targets based on cone beam computed tomography (CBCT) guidance. As a more effective method to localize soft tissue targets, we developed an online bioluminescence tomography (BLT) system for small-animal radiation research platform (SARRP). We demonstrated BLT-guided radiation therapy and validated targeting accuracy based on a newly developed reconstruction algorithm.

METHODS AND MATERIALS

The BLT system was designed to dock with the SARRP for image acquisition and to be detached before radiation delivery. A 3-mirror system was devised to reflect the bioluminescence emitted from the subject to a stationary charge-coupled device (CCD) camera. Multispectral BLT and the incomplete variables truncated conjugate gradient method with a permissible region shrinking strategy were used as the optimization scheme to reconstruct bioluminescent source distributions. To validate BLT targeting accuracy, a small cylindrical light source with high CBCT contrast was placed in a phantom and also in the abdomen of a mouse carcass. The center of mass (CoM) of the source was recovered from BLT and used to guide radiation delivery. The accuracy of the BLT-guided targeting was validated with films and compared with the CBCT-guided delivery. In vivo experiments were conducted to demonstrate BLT localization capability for various source geometries.

RESULTS

Online BLT was able to recover the CoM of the embedded light source with an average accuracy of 1 mm compared to that with CBCT localization. Differences between BLT- and CBCT-guided irradiation shown on the films were consistent with the source localization revealed in the BLT and CBCT images. In vivo results demonstrated that our BLT system could potentially be applied for multiple targets and tumors.

CONCLUSIONS

The online BLT/CBCT/SARRP system provides an effective solution for soft tissue targeting, particularly for small, nonpalpable, or orthotopic tumor models.

Structure-function studies of the bHLH phosphorylation domain of TWIST1 in prostate cancer cells

The TWIST1 gene has diverse roles in development and pathologic diseases such as cancer. TWIST1 is a dimeric basic helix-loop-helix (bHLH) transcription factor existing as TWIST1-TWIST1 or TWIST1-E12/47. TWIST1 partner choice and DNA binding can be influenced during development by phosphorylation of Thr125 and Ser127 of the Thr-Gln-Ser (TQS) motif within the bHLH of TWIST1. The significance of these TWIST1 phosphorylation sites for metastasis is unknown. We created stable isogenic prostate cancer cell lines overexpressing TWIST1 wild-type, phospho-mutants, and tethered versions. We assessed these isogenic lines using assays that mimic stages of cancer metastasis. In vitro assays suggested the phospho-mimetic Twist1-DQD mutation could confer cellular properties associated with pro-metastatic behavior. The hypo-phosphorylation mimic Twist1-AQA mutation displayed reduced pro-metastatic activity compared to wild-type TWIST1 in vitro, suggesting that phosphorylation of the TWIST1 TQS motif was necessary for pro-metastatic functions. In vivo analysis demonstrates that the Twist1-AQA mutation exhibits reduced capacity to contribute to metastasis, whereas the expression of the Twist1-DQD mutation exhibits proficient metastatic potential. Tethered TWIST1-E12 heterodimers phenocopied the Twist1-DQD mutation for many in vitro assays, suggesting that TWIST1 phosphorylation may result in heterodimerization in prostate cancer cells. Lastly, the dual phosphatidylinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) inhibitor BEZ235 strongly attenuated TWIST1-induced migration that was dependent on the TQS motif. TWIST1 TQS phosphorylation state determines the intensity of TWIST1-induced pro-metastatic ability in prostate cancer cells, which may be partly explained mechanistically by TWIST1 dimeric partner choice.

Abstract 2291: Snai1 accelerates Kras driven lung tumorigenesis by overcoming oncogene-induced senescence

Lung cancer is the deadliest cancer worldwide with the majority of cases being non-small cell lung cancer (NSCLC). The most common oncogenic driver in NSCLC patients is mutant KRAS. Mutant KRAS driven proliferation is abated by the failsafe mechanism of oncogene-induced senescence (OIS) in primary cell lines. TWIST1, an inducer of epitheilal-mesenchymal transition (EMT), can overcome OIS, rescuing proliferative capacity of mutant KRAS in primary cells. SNAI1 is another classical EMT master regulator critical in development and is aberrantly expressed in breast, liver, colon, and lung cancers. SNAI1 expression correlates with tumor recurrence and poor patient prognosis. However, there is no evidence for the role of SNAI1 in autochthonous lung tumorigenesis in vivo. To study SNAI1 in lung tumorigenesis, we developed a novel inducible SNAI1 transgenic mouse model. The Club Cell Secretory Protein (CCSP)-rtTA (C) lung tissue specific driver founder line was crossed with a bidirectional transgenic founder line, SNAI1-6SA-tetO7-luc (S), to generate CS mice. CS mice were crossed with inducible oncogenic driver tetO7-KrasG12D (R) mice to produce the triple transgenic, CRS. Inducible SNAI1 expression was confirmed by multiple methods in this novel mouse model. Interestingly, a Kaplan-Meier curve analysis showed that SNAI1 overexpression accelerated KrasG12D-driven lung tumorigenesis compared to KrasG12D alone in vivo. SNAI1 reduced median KrasG12D tumor latency from 31 to 15 weeks of doxycycline (DOX) induction and SNAI1 driven CRS mice developed more aggressive lung adenocarcinomas than the CR model. Upon DOX removal lung tumor moribund mice demonstrated complete radiographic tumor regression, demonstrating tumor maintenance in CRS mice is dependent on KrasG12D and/or SNAI1. To begin to elucidate how SNAI1 may accelerate lung tumorigenesis, inducible SNAI1 mouse embryonic fibroblasts (MEFs) were generated. These MEFs were used to assess if SNAI1 could suppress OIS and promote HRASG12V driven proliferation. While uninduced MEFs senesced within days of HRASG12V infection, DOX induced SNAI1 MEFs had a reduced number of senescence associated Beta-gal positive cells. Furthermore, cellular proliferation showed stagnancy in uninduced HRASG12V infected MEFs, while induced SNAI1 MEFs maintained proliferative capacity. Studies investigating SNAI1-directed epigenetic and transcriptional regulation of metabolic gene targets implicated in circumventing OIS in this model are underway. Overall, these studies demonstrate that SNAI1 may overcome OIS in mutant RAS driven cells to facilitate cellular proliferation and tumorigenesis.

Citation Format: Kekoa Taparra, Hailun Wang, Katriana Nugent, Russell Williams, Reem Malek, Jessica Cades, Dean Felsher, Phuoc Tran. Snai1 accelerates Kras driven lung tumorigenesis by overcoming oncogene-induced senescence. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2291. doi:10.1158/1538-7445.AM2015-2291

Contribution of transmission in HIV-positive men who have sex with men to evolving epidemics of sexually transmitted infections in England: an analysis using multiple data sources, 2009-2013

HIV seroadaptive behaviours may have contributed to greater sexually transmitted infection (STI) transmission in HIV-positive men who have sex with men(MSM) and to the global increase in STIs. Using multiple national surveillance data sources and population survey data, we estimated the risk of STIs in HIV-positive MSM and assessed whether transmission in HIV-positive MSM has contributed to recent STI epidemics in England. Since 2009, an increasing proportion of STIs has been diagnosed in HIV-positive MSM, and currently, the population rate of acute bacterial STIs is up to four times that of HIV-negative or undiagnosed MSM. Almost one in five of all diagnosed HIV-positive MSM in England had an acute STI diagnosed in 2013. From 2009 to 2013, the odds of being diagnosed with syphilis increased from 2.71 (95% confidence interval (CI) 2.41–3.05, p<0.001) to 4.05 (95%CI 3.70-4.45, p<0.001) in HIV-positive relative to HIV negative/undiagnosed MSM. Similar trends were seen for gonorrhoea and chlamydia. Bacterial STI re-infection rates were considerably higher in HIV-positive MSM over a five-year follow-up period, indicative of rapid transmission in more dense sexual networks.These findings strongly suggest that the sexual health of HIV-positive MSM in England is worsening, which merits augmented public health interventions and continued monitoring.

Abstract B16: Dissecting MDM2 function in medulloblastoma pathogenesis

Treatment for medulloblastoma (MB), a tumor of the cerebellum, involves an aggressive regimen of surgical resection, radiation and adjuvant chemotherapy. Although the 5-year cure rate is over 50%, most children retain life-long side effects associated with treatment, including reduced intellect. There is an urgent need to develop multi-targeted therapeutic strategies that enhance the killing of MB tumor cells while sparing normal cells. As a critical component of the cellular response to stress, p53 function is required for the cytotoxic effects of many chemotherapeutics. As p53 mutations are relatively rare in MB, adjuvant chemotherapeutics that enhance p53 function may have a profound effect in MB. Indeed, we previously reported that pharmacological disruption of the interaction of p53 with its negative regulator, MDM2, potentiates cell killing in human medulloblastoma cells. In order to gain further insight into the role of MDM2 in MB pathogenesis, here we have used a combination of wild-type, null, and hypomorphic alleles of MDM2 to perturb the MDM2-p53 pathway in Ptch1+/- mice, a model of human Sonic hedgehog (Shh)-induced MB. Our studies demonstrate that a 70% reduction in the level of MDM2 abrogates the formation of preneoplastic lesions (PNLs) in the cerebellum of Ptch1+/- mice, thereby supporting a requirement for MDM2 in MB initiation. Significantly, even a modest ~50% reduction in the level of MDM2 was sufficient to decrease PNL formation in the Ptch1+/- cerebellum in two-fold. Although reduced in number, detailed histological analyses of PNLs at P21 revealed no difference in the size, proliferation or apoptosis of PNLs between Ptch1+/- mice expressing a wild-type or 50% reduced level of MDM2. Next, we examined granule neuron precursors (GNPs) in the external granule layer (EGL) at P7, the pool of cells from which PNLs are presumed to originate. Consistent with the partial deregulation of Shh signaling in Ptch1+/- mice, the Ptch1+/- EGL was more highly proliferative than that of wild-type mice. Importantly, we found that the enhanced proliferation of EGL cells afforded by loss of one Ptch1 allele was restored back to wild-type levels when the level of MDM2 is reduced. Additionally, a 50% in the level of MDM2 potentiates apoptosis and enhances the steady state level of p53SER15 in the EGL in Ptch1+/- mice as compared to control mice. Dysregulation of the MDM2-p53 and Sonic hedgehog (Shh)-Gli pathways are both implicated in the pathogenesis of human MB; however, no approach to date has yielded a detailed understanding of how crosstalk between these two important pathways contributes to the proliferation, survival, and differentiation of GNPs, the presumed cell of origin for some MB subtypes. Our prior studies placed MDM2 at a critical node between the growth inhibiting the p53 pathway and the growth-promoting Shh-Gli pathway in normal cerebellar development. New work presented here further suggests that MDM2 is required for MB tumorigenesis to prevent p53 activation, which may in turn function to counteract deregulated Shh-mediated proliferation in the tumor initiating cell population. The coordinate regulation of these two important pathways may provide a mechanism to sustain tumor-promoting levels of Shh-Gli signaling without activating the tumor-suppressing functions of p53. By nature of its requirement in MB tumorigenesis, MDM2 may provide an important therapeutic target for boosting the efficacy of current MB treatments.

Citation Format: Susan M. Mendrysa, Reem Malek. Dissecting MDM2 function in medulloblastoma pathogenesis. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr B16.

Effects of short-term sitagliptin treatment on immune parameters in healthy individuals, a randomized placebo-controlled study

Sitagliptin, a dipeptidyl-peptidase 4 (DPP-4) inhibitor, improves blood glucose control in patients with type 2 diabetes by blocking cleavage of glucagon-like peptide 1 (GLP-1). In type 2 diabetes patients sitagliptin use is associated with an increase in minor infections, and in new-onset type 1 diabetes patients the ability of sitagliptin to dampen autoimmunity is currently being tested. DPP-4, also known as CD26, is expressed on leucocytes and can inactivate many chemokines important for leucocyte migration, as well as act as a co-stimulatory molecule on T cells. Therefore, this study was conducted to test whether sitagliptin is immunomodulatory. In this randomized, placebo-controlled trial, healthy volunteers were given sitagliptin or placebo daily for 28 days, and blood was drawn for immune assays. No significant differences were observed in the percentage of leucocyte subsets within peripheral blood mononuclear cells (PBMCs), plasma chemokine/cytokine levels or cytokines released by stimulation of PBMCs with either lipopolysaccharide (LPS) or anti-CD3. Individuals taking sitagliptin displayed increases in the percentage of cells expressing higher levels of CD26 at early time-points compared to placebo controls, but these differences resolved by day 28 of treatment. Therefore, in healthy volunteers, treatment with sitagliptin daily for 28 days does not overtly alter systemic immune function.

Mutations in Lyar and p53 are synergistically lethal in female mice

BACKGROUND

Ly-1 antibody reactive clone (LYAR) is a nucleolar zinc finger protein that has been implicated in cell growth, self-renewal of embryonic stem cells, and medulloblastoma. To test whether LYAR is critical for cell growth and development, we generated Lyar mutant mice.

METHODS

Mice carrying the mutant Lyar(gt) allele were generated from embryonic stem cells that contained a gene-trap insertion in the Lyar gene. Phenotypic analyses were performed on Lyar mutant mice and mouse embryonic fibroblasts. Lyar(gt/gt) mice were crossed to mice lacking the p53 tumor suppressor protein and Lyar/p53 compound mutants scored for external abnormalities.

RESULTS

Lyar(gt/gt) homozygotes are viable, fertile, and indistinguishable from wild type littermates. However, the growth of Lyar(+/gt) and Lyar(gt/gt) mouse embryonic fibroblasts (MEFs) was impaired, coincident with an increase in the steady-state level of p53 and a key p53 effector of growth arrest, p21, suggesting that a cellular stress response is triggered in the absence of a wild type level of LYAR. Remarkably, the majority of Lyar(+/gt) and Lyar(gt/gt) female mice lacking p53 mice failed to survive. The neural tube defect (NTD) exencephaly was observed in ≈26% and ≈61% of female Lyar(+/gt;) p53(-/-) and Lyar(gt/gt;) p53(-/-) embryos, respectively.

CONCLUSIONS

Lyar/p53 mutant mice represent a new digenic model of NTDs. Furthermore, these studies identify Lyar as a novel candidate gene for a role in human NTDs. These results provide new data to support the idea that loss of a p53-mediated developmental checkpoint may increase the risk of NTDs owing to some germline mutations.

Abstract 5213: MDM2 at the crossroads of cell fate decisions in cerebellar development and medulloblastoma

During post-natal cerebellar development, Granule Neuron Precursors (GNPs) undergo a proliferative expansion in response to Sonic hedgehog (Shh) signaling, prior to differentiation and migration to their final niche. Aberrations in this tightly controlled process can tip the balance toward persistent proliferation leading to Medulloblastoma (MB), or toward apoptosis or premature differentiation leading to neurodegeneratiion. Here, we report that MDM2, the principal inhibitor of the p53 tumor suppressor protein, is required for cerebellum development as well as for MB tumorigenesis. Our studies employed a novel hypomorphic allele of Mdm2 (Mdm2puro) in combination with the Mdm2del7-9 null allele. Mdm2puro/del7-9 mice express ∼30% of the wild-type level of MDM2. Mdm2puro/del7-9 cerebella exhibit decreased foliation, reduction in GNP numbers, and laminar disorganization. These phenotypes are attributed, in part, to high levels of p53-dependent apoptosis. In addition, we have recently determined through fate mapping studies that loss of MDM2 also promotes the premature migration of GNPs. Global transcriptome analyses of the Mdm2puro/del7-9 cerebellum supports dysregulation of the transcriptional programs that regulate GNP differentiation. Further, Western blot analyses reveal an increase in the pro-differentiation protein, Numb, and the neuronal maturation marker, βIII-Tubulin, in GNPs. A concomitant decrease in Gli1 and Gli2, two effectors of Shh signaling known to be degraded by Numb, suggests an increase in Numb activity. These experiments suggest that loss of MDM2 and subsequent increase in p53 activity accelerates GNPs migration and possibly favors GNP differentiation over proliferation. In complementary experiments, we employed Shh-responsive primary GNP cultures from wild-type mice. Shh stimulation of GNPs results in an increase in the steady state level of MDM2 and an increase in MDM2 phosphorylation at Ser166, a modification known to enhance the anti-p53 function of MDM2. These findings suggest that Shh signaling may upregulate MDM2 to prevent p53 activation during GNP proliferation. In keeping with the concept that GNP proliferation and MB tumor formation are governed by similar mechanisms, we also observed increased levels of p-MDM2Ser166 in Shh-induced preneoplastic lesions (PNLs) and MB tumors in a Ptch1+/- mice, a model of human MB. Notably, a 70% reduction in the level of MDM2 in these mice abrogates the formation of PNLs, supporting a key role for MDM2 in the initiation of some types of MB. Overall, our results suggest that MDM2 mediated inhibition of p53 plays in important role in survival and migration of GNPs cerebellum development. This role of MDM2 may be high-jacked by deregulated Shh signaling in certain MB tumors thereby limiting the tumor suppressive function of p53 and obviating a need for p53 gene mutations.

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 5213. doi:1538-7445.AM2012-5213

Endovascular mechanical thrombectomy for the treatment of acute ischemic stroke due to arterial dissection

Arterial dissections account for 2% of strokes in all age groups, and up to 25% in patients aged 45 years or younger. The safety of endovascular intervention in this patient population is not well characterized. We identified all patients in the Merci registry - a prospective, multi-center post-market database enrolling patients treated with the Merci Retriever thrombectomy device - with arterial dissection as the most likely stroke etiology. Stroke presentation and procedural details were obtained prospectively; data regarding procedural complications, intracerebral hemorrhage (ICH), and the use of stenting of the dissected artery were obtained retrospectively. Of 980 patients in the registry, ten were identified with arterial dissection (8/10 ICA; 2/10 vertebrobasilar). The median age was 48 years with a baseline NIH stroke scale score of 16 and median time to treatment of 4.9 h. The procedure resulted in thrombolysis in cerebral ischemia (TICI) scores of 2a or better in eight out of ten and TICI 2b or better in six out of ten patients. Stenting of the dissection was performed in four of nine (44%). The single complication (1/9; 11%) - extension of a dissected carotid artery - was treated effectively with stenting. No symptomatic ICH or stroke in a previously unaffected territory occurred. A favorable functional outcome was observed in eight out of ten patients. Despite severe strokes on presentation, high rates of recanalization (8/10) and favorable functional outcomes (8/10) were observed. These results suggest that mechanical thrombectomy in patients with acute stroke resulting from arterial dissection is feasible, safe, and may be associated with favorable functional outcomes.

p53 in the CNS: Perspectives on Development, Stem Cells, and Cancer

The p53 tumor suppressor potently limits the growth of immature and mature neurons under conditions of cellular stress. Although loss of p53 function contributes to the pathogenesis of central nervous system (CNS) tumors, excessive p53 function is implicated in neural tube defects, embryonic lethality, and neuronal degeneration. Thus, p53 function must be tightly controlled. The anti-proliferative properties of p53 are mediated, in part, through the induction of apoptosis, cell cycle arrest, and senescence. Although there is still much to be learned about the role of p53 in these processes, recent evidence supports exciting new roles for p53 in a wide range of processes, including neural precursor cell self-renewal, differentiation, and cell fate decisions. Understanding the full repertoire of p53 function in CNS development and tumorigenesis may provide us with novel points of therapeutic intervention for human diseases of the CNS.

The p53 inhibitor MDM2 facilitates Sonic Hedgehog-mediated tumorigenesis and influences cerebellar foliation

Disruption of cerebellar granular neuronal precursor (GNP) maturation can result in defects in motor coordination and learning, or in medulloblastoma, the most common childhood brain tumor. The Sonic Hedgehog (Shh) pathway is important for GNP proliferation; however, the factors regulating the extent and timing of GNP proliferation, as well as GNP differentiation and migration are poorly understood. The p53 tumor suppressor has been shown to negatively regulate the activity of the Shh effector, Gli1, in neural stem cells; however, the contribution of p53 to the regulation of Shh signaling in GNPs during cerebellar development has not been determined. Here, we exploited a hypomorphic allele of Mdm2 (Mdm2(puro)), which encodes a critical negative regulator of p53, to alter the level of wild-type MDM2 and p53 in vivo. We report that mice with reduced levels of MDM2 and increased levels of p53 have small cerebella with shortened folia, reminiscent of deficient Shh signaling. Indeed, Shh signaling in Mdm2-deficient GNPs is attenuated, concomitant with decreased expression of the Shh transducers, Gli1 and Gli2. We also find that Shh stimulation of GNPs promotes MDM2 accumulation and enhances phosphorylation at serine 166, a modification known to increase MDM2-p53 binding. Significantly, loss of MDM2 in Ptch1(+/-) mice, a model for Shh-mediated human medulloblastoma, impedes cerebellar tumorigenesis. Together, these results place MDM2 at a major nexus between the p53 and Shh signaling pathways in GNPs, with key roles in cerebellar development, GNP survival, cerebellar foliation, and MB tumorigenesis.

Treatment of type B insulin resistance: a novel approach to reduce insulin receptor autoantibodies

BACKGROUND

Type B insulin resistance belongs to a class of diseases caused by an autoantibody to a cell surface receptor. Blockade of insulin action results in hyperglycemia, hypercatabolism, severe acanthosis nigricans, and hyperandrogenism in women. This rare autoimmune disorder has been treated with various forms of immunosuppression with mixed success.

METHODS

We describe 14 patients with type B insulin resistance referred to the National Institutes of Health, adding to an existing cohort of 24 patients. This report focuses on seven patients who were treated with an intensive combination protocol of rituximab, cyclophosphamide, and pulse corticosteroids aimed at control of pathogenic autoantibody production. Hematological, metabolic, and endocrine parameters, including fasting glucose, glycated hemoglobin, insulin dose, lipids, and testosterone, were monitored before and after treatment.

RESULTS

All seven treated patients achieved remission, defined as amelioration of hyperglycemia, discontinuation of insulin therapy, and resolution of hyperandrogenism. Glycated hemoglobin has normalized in all seven treated patients. Remission was achieved on average in 8 months from initiation of treatment. The medication regimen was well tolerated, with no serious adverse events.

CONCLUSIONS

In seven patients with type B insulin resistance, standardized treatment with rituximab, cyclophosphamide, and pulse steroids results in remission of the disease. Future studies will determine whether this treatment protocol can be applied to other autoantibody/cell surface receptor disease states.

Frequency of the 35delG allele causing nonsyndromic recessive deafness in the Algerian patients

Deafness is a heterogeneous disorder showing different patterns of inheritance and involving a multitude of different genes. Mutations in the GJB2 gene encoding connexin 26 (Cx26) protein are a major cause for non-syndromic autosomal recessive and sporadic deafness. Among these mutations, the c.35delG deletion is the most common mutation for sensorineural deafness. One hundred sixteen persons from fifty-eight families were tested by the method based on the principle of PCR-mediated-site-directed mutagenesis (PSDM), followed by a Bsl1 digestion. Mutation c.35delG was diagnosed in sixteen families (11 homozygotes and 5 heterozygotes). The low allelic frequency (17.24%) and low ratio of individuals homozygous (13.8%) and heterozygous (6.9%) for the c.35delG mutation suggest that there are other mutations in the GJB2 gene or other genes responsible for deafness in the Algerian population. This study reports a significant association (P=0.003) between first cousin consanguinity and non-syndromic prelingual deafness.

Should the presence of congenital para-ureteral diverticulum affect the management of vesicoureteral reflux?

PURPOSE

The presence of congenital para-ureteral diverticulum (PUD) has been presumed to lower the resolution rate of vesicoureteral reflux (VUR). PUD is considered an important cause of distortion of the vesicoureteral junction and persistence of VUR. Early surgery has been recommended based on this assumption. However, the scientific evidence supporting this approach is weak. We have been managing this group of patients more conservatively in the last 7 to 8 years on the premise that the presence of PUD is not per se an indication for surgery. To test this hypothesis, we performed a retrospective cohort study to compare the outcome of VUR in children with and without PUD.

MATERIALS AND METHODS

We identified 141 consecutive patients with VUR associated with PUD between 1990 and 2004. Of the patients 57 with duplication, ureterocele, neurogenic bladder or outlet obstruction were excluded from study. Median age of the remaining 84 patients at diagnosis was 2.9 years and 56 (69%) were males. Reflux was bilateral in 4 patients, and low (I to II), intermediate (III) and high (IV to V) grade in 39%, 35% and 26%, respectively. Followup was 3 to 168 months (median 47). The outcome was compared to a control group of 95 patients (150 units) with primary VUR and no PUD. The baseline parameters and followup were comparable in both groups.

RESULTS

Overall, VUR resolved in 43%, persisted in 27% and was surgically corrected in 30% of the units with PUD. In the 25 patients (26 units) who underwent surgical intervention breakthrough urinary tract infection or new renal scars were the indication in only 5. The remainder were operated on because of persistent VUR and the presence of PUD, mainly before 1997. The incidence of breakthrough urinary tract infection or new renal scar was similar in the controls (6% in PUD group vs 10% in controls, p = 0.7). The resolution rate was 60% for low grade, 39% for intermediate grade and 22% for high grade VUR. These figures were not significantly different from those of the control group in which the resolution rates were 52%, 28% and 33% for comparable grades (p = 0.9). Kaplan-Meier analysis and log rank test did not show any difference in resolution of VUR in the 2 groups (p = 0.84). Multivariate analysis identified grade as the only variable affecting resolution (p = 0.028). The size of PUD did not affect the likelihood of resolution.

CONCLUSIONS

The outcome of VUR is similar in children with or without PUD. Therefore, treatment of these patients should not differ. Surgery should be reserved for patients with breakthrough infection or renal scar progression.