Chronic exposure to cadmium induces a malignant transformation of benign prostate epithelial cells

Epidemiological evidence suggests that cadmium (Cd) is one of the causative factors of prostate cancer, but the effect of Cd on benign prostatic hyperplasia (BPH) remains unclear. This study aimed to determine whether Cd exposure could malignantly transform BPH1 cells and, if so, to dissect the mechanism of action. We deciphered the molecular signaling responsible for BPH1 transformation via RNA-sequencing and determined that Cd induced the expression of zinc finger of the cerebellum 2 (ZIC2) in BPH1 cells. We noted Cd exposure increased ZIC2 expression in the Cd-transformed BPH1 cells that in turn promoted anchorage-independent spheroids and increased expression of stem cell drivers, indicating their role in stem cell renewal. Subsequent silencing of ZIC2 expression in transformed cells inhibited spheroid formation, stem cell marker expression, and tumor growth in nude mice. At the molecular level, ZIC2 interacts with the glioma-associated oncogene family (GLI) zinc finger 1 (GLI1), which activates prosurvival factors (nuclear factor NFκB, B-cell lymphoma-2 (Bcl2), as well as an X-linked inhibitor of apoptosis protein (XIAP)) signaling in Cd-exposed BPH1 cells. Conversely, overexpression of ZIC2 in BPH1 cells caused spheroid formation confirming the oncogenic function of ZIC2. ZIC2 activation and GLI1 signaling induction by Cd exposure in primary BPH cells confirmed the clinical significance of this oncogenic function. Finally, human BPH specimens had increased ZIC2 versus adjacent healthy tissues. Thus, we report direct evidence that Cd exposure induces malignant transformation of BPH via activation of ZIC2 and GLI1 signaling.

Abstract 4810: Targeting androgen receptor in combination with cisplatin: Effective treatment strategy for muscle invasive bladder cancer

Background: Bladder cancer is one of the major causes of cancer death in US and worldwide. Cisplatin is a key component of chemotherapeutic regimens employed in the treatment of advanced bladder cancer. The role of androgen and androgen receptor (AR) signaling in bladder cancer remains uncharacterized.

Aim: The aim of the study is to delineate the role of AR in bladder cancer and to determine whether combination of AR inhibitor, enzalutamide (Enz) and cisplatin-based therapies effectively inhibit the growth of muscle invasive bladder cancer (MIBC).

Methods: AR expression was determined in 75 human bladder cancer specimens and in a panel of bladder cancer cell lines. Cells grown in charcoal stripped media supplemented with dihydrotestosterone (DHT) were treated with cisplatin, enzalutamide (AR inhibitor), or a combination of both. Cellular/phenotypic analysis including MTT assay, apoptotic assay, migration as well as invasion assays and molecular analysis including western blotting, real time PCR analysis were performed. Isobologram analysis for the combination was performed and analyzed with CompuSyn. Experiments were repeated in triplicates and analyzed with unpaired Student's t-test and one way ANOVA *p≤0.05, **p≤0.01, ***p≤0.001.

Results: AR expression was seen in around 40% of bladder cancer patients. Inhibition of AR signaling by enzalutamide effectively inhibited the growth of AR+ MIBC cells. Interestingly, enzalutamide in combination with cisplatin (Enz + Cis) synergistically inhibited the proliferation of MIBC cells, TCCSUP (CI: 0.42, 1.25 + 5 μM) and J82 (CI: 0.79, 2.5 + 5 μM) at low concentrations of enzalutamide and cisplatin resp.. The molecular studies revealed the induction of DNA damage markers (pATM, pATR, pChk1, pHis) and enhanced expression of the pro-apoptotic genes (Bax, caspases-3 and PARP) in Enz+Cis treated AR+ MIBC cells. In addition, we demonstrated abrogation of invasive and migratory potential with Enz+Cis treatment, by downregulation of the mesenchymal markers (N-cadherin, slug, β-catenin, and vimentin) in both cell lines. Our studies suggest combination of Enz + Cis may be effective in patients with AR+ MIBC.

Conclusion: Combination of cisplatin and AR inhibition effectively inhibit bladder tumor growth and migration, and hold promise as synergetic therapies for AR+ bladder cancer patients.

Citation Format: Ashish Tyagi, Balaji Chandersekaran, Samarpit Rai, Houda Alatassi, Ahmed Q. Haddad, Murali K. Ankem, Chendil Damodaran. Targeting androgen receptor in combination with cisplatin: Effective treatment strategy for muscle invasive bladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4810.

Shed urinary ALCAM is an independent prognostic biomarker of three-year overall survival after cystectomy in patients with bladder cancer

Proteins involved in tumor cell migration can potentially serve as markers of invasive disease. Activated Leukocyte Cell Adhesion Molecule (ALCAM) promotes adhesion, while shedding of its extracellular domain is associated with migration. We hypothesized that shed ALCAM in biofluids could be predictive of progressive disease. ALCAM expression in tumor (n = 198) and shedding in biofluids (n = 120) were measured in two separate VUMC bladder cancer cystectomy cohorts by immunofluorescence and enzyme-linked immunosorbent assay, respectively. The primary outcome measure was accuracy of predicting 3-year overall survival (OS) with shed ALCAM compared to standard clinical indicators alone, assessed by multivariable Cox regression and concordance-indices. Validation was performed by internal bootstrap, a cohort from a second institution (n = 64), and treatment of missing data with multiple-imputation. While ALCAM mRNA expression was unchanged, histological detection of ALCAM decreased with increasing stage (P = 0.004). Importantly, urine ALCAM was elevated 17.0-fold (P < 0.0001) above non-cancer controls, correlated positively with tumor stage (P = 0.018), was an independent predictor of OS after adjusting for age, tumor stage, lymph-node status, and hematuria (HR, 1.46; 95% CI, 1.03–2.06; P = 0.002), and improved prediction of OS by 3.3% (concordance-index, 78.5% vs. 75.2%). Urine ALCAM remained an independent predictor of OS after accounting for treatment with Bacillus Calmette-Guerin, carcinoma in situ, lymph-node dissection, lymphovascular invasion, urine creatinine, and adjuvant chemotherapy (HR, 1.10; 95% CI, 1.02–1.19; P = 0.011). In conclusion, shed ALCAM may be a novel prognostic biomarker in bladder cancer, although prospective validation studies are warranted. These findings demonstrate that markers reporting on cell motility can act as prognostic indicators.

Prognostic value of tissue-based biomarker signature in clear cell renal cell carcinoma

OBJECTIVE

To improve risk stratification for recurrence prognostication in patients with localised clear cell renal cell carcinoma (ccRCC).

PATIENTS AND METHODS

In all, 367 patients with non-metastatic ccRCC were included. The cohort was divided into a training and validation set. Using tissue microarrays, immunostaining was performed for 24 biomarkers representative of key pathways in ccRCC. Using Least Absolute Shrinkage and Selection Operator (LASSO) Cox regression, we identified several markers that were used to construct a risk classifier for risk of disease recurrence.

RESULTS

The median (interquartile range) follow-up was 63.5 (24.0-85.3) months. Five out of 24 markers were selected by LASSO Cox regression for the risk classifier: N-cadherin, E-cadherin, Ki67, cyclin D1 and phosphorylated eukaryotic initiation factor 4E binding protein-1 (p-4EBP1). Patients were classified as either low, intermediate or high risk of disease recurrence by tertiles of risk score. The 5-year recurrence-free survival (RFS) was 93.8%, 87.7% and 70% for patients with low-, intermediate- and high-risk scores, respectively (P < 0.001). Patients with a high marker score had worse RFS on multivariate analysis adjusted for age, gender, race and the Mayo Clinic Stage, Size, Grade, and Necrosis (SSIGN) score (hazard ratio 3.66, 95% confidence interval 1.58-8.49, P = 0.003 for high vs low marker score in the overall cohort). The five-marker classifier increased the concordance index of the clinical model in both the training and validation sets.

CONCLUSION

We developed a five-marker-based prognostic tool that can effectively classify patients with ccRCC according to risk of disease recurrence after surgery. This tool, if prospectively validated, could provide individualised risk estimation for patients with ccRCC.

Gossypiboma manifesting as urachal mass

Gossypiboma (retained surgical sponge) occurs between 1 in 1000 and 1 in 1500 of all intra-abdominal operations. Patients with gossypibomas may present asymptomatically or with nonspecific symptoms, such as abdominal pain or bloating; identification frequently relies on imaging. Results of imaging alone, however, may appear nonspecific, and the gossypiboma may mimic other masses, such as neoplasms, hematomas, or abscesses. They require surgical removal for definitive diagnosis and treatment. Herein we present an unusual case of gossypiboma masquerading as an urachal mass in a 75-year-old woman. Diagnostic evaluation, natural history, and prevention of retained surgical materials are discussed.

Association of distance to treatment facility on quality and survival outcomes after radical cystectomy for bladder cancer

OBJECTIVE

To examine the association of travel distance on quality and survival outcome measures for bladder cancer patients undergoing radical cystectomy for urothelial carcinoma.

METHODS

Four hundred eight patients who underwent radical cystectomy for bladder cancer at a single institution from 2007 to 2013 were included. Multivariate logistic regression was used to determine the association of distance from treatment facility with 90-day mortality and quality-of-care endpoints including neoadjuvant chemotherapy use and time to cystectomy. Survival was assessed by multivariate Cox regression.

RESULTS

Fifty-seven percent of patients lived within 50 miles of the treatment facility. There was no difference in time to cystectomy or the utilization of neoadjuvant chemotherapy between patients in different distance groups. On multivariate analysis, distance to treatment facility was the only predictor of 90-day mortality (odds ratio, 11.20; 95% confidence interval, 2.27-55.43; P = .003, for patients traveling >150 vs <50 miles). Although there was no difference in recurrence and cancer-specific survival between distance groups, greater distance was associated with worse overall survival on multivariate analysis (hazard ratio, 1.59; 95% confidence interval, 0.99-2.56; P = .05, for patients traveling >150 vs <50 miles).

CONCLUSION

Distance to treatment facility did not impact quality measures including time to cystectomy or use of neoadjuvant chemotherapy, and there was no difference in cancer-specific mortality between distance groups. There was a detrimental association of increased travel distance with 90-day mortality, which could reflect disparities in access to care after cystectomy.

Preoperative multivariable prognostic models for prediction of survival and major complications following surgical resection of renal cell carcinoma with suprahepatic caval tumor thrombus

OBJECTIVE

Surgical resection for renal cell carcinoma (RCC) with suprahepatic inferior vena cava tumor thrombus is associated with significant morbidity, yet there are currently no tools for preoperative prognostic evaluation. Our goal was to develop a preoperative multivariable model for prediction of survival and risk of major complications in patients with suprahepatic thrombi.

METHODS

We identified patients who underwent surgery for RCC with suprahepatic tumor thrombus extension from 2000 to 2013 at 4 tertiary centers. A Cox proportional hazard model was used for analysis of overall survival (OS) and logistic regression was used for major complications within 90 days of surgery (Clavien ≥ 3A). Nomograms were internally calibrated by bootstrap resampling method.

RESULTS

A total of 49 patients with level III thrombus and 83 patients with level IV thrombus were identified. During median follow-up of 24.5 months, 80 patients (60.6%) died and 46 patients (34.8%) experienced major complication. Independent prognostic factors for OS included distant metastases at presentation (hazard ratio = 2.52, P = 0.002) and Eastern Cooperative Oncology Group (ECOG) performance status (hazard ratio = 1.84, P<0.0001). Variables associated with increased risk of major complications on univariate analysis included preoperative systemic symptoms, level IV thrombus, and elevated preoperative alkaline phosphatase and aspartate transaminase levels; however, only systemic symptoms (odds ratio = 8.45, P<0.0001) was an independent prognostic factor. Preoperative nomograms achieved a concordance index of 0.72 for OS and 0.83 for major complications.

CONCLUSIONS

We have developed and internally validated multivariable preoperative models for the prediction of survival and major complications in patients with RCC who have a suprahepatic inferior vena cava thrombus. If externally validated, these tools may aid in patient selection for surgical intervention.

Tumour and patient factors in renal cell carcinoma-towards personalized therapy

Renal cell carcinoma (RCC) comprises a heterogeneous group of histologically and molecularly distinct tumour subtypes. Current targeted therapies have improved survival in patients with advanced disease but complete response occurs rarely, if at all. The genomic characterization of RCC is central to the development of novel targeted therapies. Large-scale studies employing multiple 'omics' platforms have led to the identification of key driver genes and commonly altered pathways. Specific molecular alterations and signatures that correlate with tumour phenotype and clinical outcome have been identified and can be harnessed for patient management and counselling. RCC seems to be a remarkably diverse malignancy with significant intratumour and intertumour genetic heterogeneity. The tumour microenvironment is increasingly recognized as a vital regulator of RCC tumour biology. Patient factors, including immune response and drug metabolism, vary widely, which can lead to widely divergent responses to drug therapy. Intratumour heterogeneity poses a significant challenge to the development of personalized therapies in RCC as a single biopsy might not accurately represent the clonal population ultimately responsible for aggressive biologic behaviour. On the other hand, the diversity of genomic alterations in RCC could also afford opportunities for targeting unique pathways based on analysis of an individual tumour's molecular composition.

Multi-institutional validation of the predictive value of Ki-67 in patients with high-grade urothelial carcinoma of the upper urinary tract

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Background: To validate the independent predictive value of Ki-67 in patients with high-grade upper tract urothelial carcinoma (UTUC). Methods: 475 patients from the international UTUC collaboration who underwent extirpative surgery for high-grade UTUC were included in this study. Immunohistochemical staining for Ki-67 was performed on tissue microarray (TMA) formed from this patient cohort. Ki-67 expression was assessed in a semi-quantitative fashion and considered overexpressed at a cut-off of 20%. Multivariate analyses (MVA) were performed to assess independent predictors of oncological outcomes and Harrell’s C indices (HCI) were calculated for predictive models. Results: Median age of the cohort was 69.7 years and 55.2% of patients were male. Ki-67 was overexpressed in 25.9% of patients. Ki-67 overexpression was significantly associated with ureteral tumor location, higher pT-stage, lymphovascular invasion, sessile tumor architecture, tumor necrosis, concomitant carcinoma in situ (CIS), and regional lymph node metastases. In Kaplan-Meier analyses, overexpressed Ki-67 was associated with worse recurrence-free (RFS) (HR 12.6, p<0.001) and cancer-specific survival (CSS) (HR 15.8, p<0.001). In MVA, Ki-67 was an independent predictor of RFS (HR 1.6, 95% CI 1.07-2.30, p=0.021) and CSS (HR 1.9, 95% CI 1.29-2.90, p=0.001). Ki-67 improved HCI from 0.66 to 0.70 (p<0.0001) for both RFS and CSS in our preoperative model, and from 0.81 to 0.82 (p=0.0018) for RFS and 0.81 to 0.83 (p=0.005) for CSS in our post-operative model. Conclusions: Ki-67 was validated as an independent prognostic predictor of RFS and CSS in patients treated with extirpative surgery for high-grade UTUC in a large, multi-institutional cohort.

Validation of mammalian target of rapamycin biomarker panel in patients with clear cell renal cell carcinoma

BACKGROUND

This was an external validation of the prognostic benefit of mammalian target of rapamycin (mTOR) marker panel in patients with clear cell renal cell carcinoma (ccRCC).

METHODS

Immunohistochemistry for 5 mTOR pathway markers was performed on tissue microarrays of patients with nonmetastatic ccRCC treated surgically at 4 centers. The markers employed were phosphatase and tensin homolog (PTEN), phosphoinositide 3-kinase (PI3K), phosphorylated-mTOR (p-mTOR), phosphorylated-S6 (p-S6), and phosphorylated 4E-binding protein-1 (p-4EBP1). Cox regression was used to correlate marker status and oncologic outcomes. Discrimination of the models was determined using area under the curve and net reclassification improvement.

RESULTS

Five hundred twenty-eight patients with a median follow-up of 56.5 months were included. Expression of PI3K, PTEN, p-mTOR, p-4EBP1, and p-S6 was altered in 52%, 78%, 25%, 86%, and 30% of patients, respectively. The number of altered biomarkers predicted recurrence-free survival (RFS) in multivariate analysis adjusted for stage, grade, and lymph node status (HR, 3.20; P = .02 for patients with 4-5 altered biomarkers compared with 0-1 altered markers). A biomarker panel consisting of only 2 markers (p-S6 and p-4EBP1) independently predicted for worse RFS (HR, 4.38; P = .003 for patients with 2 altered markers compared to patients with 0 altered markers). The biomarker score increased predictive accuracy when added to the clinical Cox regression model.

CONCLUSIONS

m-TOR pathway biomarkers add prognostic information in addition to standard clinicopathologic variables in ccRCC patients and may identify patients who could benefit from additional treatments or closer postoperative surveillance.

Surgical management of metastatic renal cell carcinoma in the era of targeted therapies

BACKGROUND

Cytoreductive nephrectomy (CN) has been considered standard management for patients with metastatic renal cell carcinoma (mRCC) for over a decade. This practice, based on evidence from the immunotherapy era, has now come into question with the dramatic shift in management of mRCC patients due to the development and approval of several targeted molecular therapies (TMT).

METHODS

A comprehensive English language literature review was performed using MEDLINE/PubMed to identify articles and guidelines pertinent to CN in mRCC.

RESULTS

Retrospective studies have demonstrated improved survival for patients who underwent CN compared to those that did not; however, these studies suffer from heavy selection bias. Furthermore, the optimal timing of TMT, before or after surgery is not known. Pre-surgical TMT has the advantage of early treatment of metastases, downsizing of the primary, and may be an effective 'litmus test' for the selection of patients for CN based on response to TMT. The results of two ongoing phase III trials (CARMENA and SURTIME) will address much of the controversy on the role of CN and the timing of systemic therapy in the TMT era. In this review, we aim to present the evidence that lead to adoption of CN in the era of immunotherapies as well as the available data about the oncologic benefit of CN in patients with mRCC who receive TMT as their primary systemic therapy.

CONCLUSION

There seems to be an important role for CN in the era of TMT, mostly in patients with favorable risk and where a high percentage of tumor burden can be removed by cytoreductive surgery.

Oncologic outcomes following surgical resection of renal cell carcinoma with inferior vena caval thrombus extending above the hepatic veins: a contemporary multicenter cohort

PURPOSE

Suprahepatic inferior vena caval tumor thrombus in renal cell carcinoma cases has historically portended a poor prognosis. With advances in perioperative treatment of patients with high level thrombus contemporary outcomes are hypothesized to be improved. We evaluated long-term oncologic outcomes of contemporary surgical treatment of patients with renal cell carcinoma in whom level III-IV inferior vena caval thrombus was managed at high volume centers.

MATERIALS AND METHODS

We examined clinical and pathological data on patients with renal cell carcinoma and level III-IV thrombus treated with surgery from January 2000 to June 2013 at 4 tertiary referral centers. Survival outcomes and associated prognostic variables were assessed by Kaplan-Meier and multivariate Cox regression analyses.

RESULTS

We identified 166 patients, including 69 with level III and 97 with level IV thrombus. Median postoperative followup was 27.8 months. Patients with no evidence of nodal or distant metastasis (pN0/X, M0) had 5-year 49.0% cancer specific survival and 42.2% overall survival. There was no difference in survival based on tumor thrombus level or pathological tumor stage. Variables associated with an increased risk of death from kidney cancer on multivariate analysis were regional nodal metastases (HR 3.94, p <0.0001), systemic metastases (HR 2.39, p = 0.01), tumor grade 4 (HR 2.25, p = 0.02), histological tissue necrosis (HR 3.11, p = 0.004) and increased preoperative serum alkaline phosphatase (HR 2.30, p = 0.006).

CONCLUSIONS

Contemporary surgical management achieves almost 50% 5-year survival in patients without metastasis who have renal cell carcinoma thrombus above the hepatic veins. Factors associated with increased mortality included nodal/distant metastases, advanced grade, histological necrosis and increased preoperative serum alkaline phosphatase. These findings support an aggressive surgical approach to the treatment of patients with renal cell carcinoma who have advanced tumor thrombus.

The degree of preoperative hydronephrosis to predict pathologic features and oncologic outcomes in high-grade upper tract urothelial carcinoma

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Background: There have been multiple reports implicating the role of hydronephrosis (HN) as a predictor of outcome in patients diagnosed with upper tract urothelial carcinoma (UTUC). However, this was done in mixed populations (low-/high-grade) and degree of HN (DOH) was not taken into account. We evaluated the impact of severity of hydronephrosis on systemic and bladder relapse in patients with UTUC. Methods: We retrospectively reviewed the records of 141 patients with localized UTUC that underwent extirpative surgery. Preoperative imaging was used to evaluate ipsilateral DOH. We analyzed the association between DOH (none/mild vs. moderate/severe), pathological findings and oncological outcomes in high-grade vs. low-grade patients. Bladder recurrence was assessed separately from local or systemic (L/S) recurrence. Results: High-grade UTUC was present in 80% of patients, 35% had muscle-invasive disease (≥pT2), and 29% had non-organ-confined disease. At a median follow-up of 34 months (range, 1-149), 35% of patients experienced intravesical recurrence, 20% developed L/S recurrence, and 17% died of UTUC. No difference in outcomes was seen between patients without HN and mild HN. DOH was none/mild in 55% and moderate/severe in 45% of cases. In patients with high-grade UTUC, moderate/severe HN was associated with advanced pathologic stage (p<0.001) and positive lymph node status (p=0.01). On Kaplan-Meier analysis, DOH was a predictor of L/S recurrence-free survival (RFS) (HR 5.5, p=0.019) and cancer-specific survival (CSS) (HR 5.2, p=0.022) but not intravesical recurrence. On multivariable analysis with preoperatively known factors controlling for grade and tumor location, DOH was independently associated with L/S RFS (HR 2.8, p=0.016) and CSS (HR 2.5, p=0.044). Conclusions: Moderate/severe HN was associated with features of advanced disease and predicted worse oncological outcomes in patients with high-grade UTUC. Since preoperative imaging is a routinely available diagnostic tool, this can serve as a surrogate parameter for advanced disease and can help to counsel patients towards preoperative chemotherapy and radical surgery.

Dysregulation of the beta-catenin complex as an independent predictor of oncological outcomes in patients with ccRCC

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Background: Epithelial to mesenchymal transition (EMT) is thought to play a crucial role in cancer progression and development of metastasis. Thus, we evaluated dysregulation of beta-catenin as a part of EMT and its clinical implications in patients with clear cell renal cell carcinoma (ccRCC). Methods: Immunohistochemical staining was performed for beta-catenin on tissue microarrays of patients with ccRCC. Membranous and cytoplasmatic beta-catenin expression patterns were assessed separately. Beta-catenin was considered normal if none or only one component was abnormal and was considered dysregulated if both components were abnormal. Differences in pathological characteristics between both groups were investigated. Differences in recurrence-free survival (RFS) and cancer-specific survival (CSS) were assessed with the Kaplan-Meier method. Uni- and multivariate Cox proportional hazard models were used to assess independent predictors of oncological outcomes. Results: 406 patients with a median follow-up of 58 months were included. Overall, 52 (12.8%) and 25 (6.2%) patients recurred and died of ccRCC. Beta-catenin was dysregulated in 70 (17.2%) patients. Dysregulation of beta-catenin was significantly associated with adverse pathologic features, such as higher T-stage, nodal positivity, higher grade, presence of tumor thrombus, sarcomatoid features, necrosis and LVI (all p<0.001). Patients with dysregulated beta-catenin had inferior RFS and CSS (both p<0.001). In multivariate analysis adjusting for tumor stage, nodal status and grade, dysregulation of beta-catenin was an independent predictor of RFS (HR 2.2, 95%CI 1.2-3.9, p=0.008) and CSS (HR 2.4, 95%CI 1.1-5.6, p=0.044). Conclusions: Our results indicate that dysregulation of beta-catenin may be an important phenomenon in ccRCC carcinogenesis. These findings support further study of beta-catenin and systematic assessment of EMT in ccRCC.

Antiproliferative mechanisms of the flavonoids 2,2'-dihydroxychalcone and fisetin in human prostate cancer cells

We have previously demonstrated the antiproliferative effect of two flavonoids-2,2'-dihydroxychalcone (DHC), a novel synthetic flavonoid, and fisetin, a naturally occurring flavonol-in prostate cancer cells. In this study, we further examine the mechanisms of these compounds on survival and proliferation pathways. DHC and fisetin (1-50 microM) caused a dose-dependent reduction in viability, a concomitant increase in apoptosis in PC3 cells at 72 h, and a decrease in clonogenic survival at 24 h treatment. DHC was considerably more potent than fisetin in these cytotoxicity assays. The mechanism of accelerated cellular senescence was not activated by either compound in PC3 or lymph node carcinoma of the prostate (LNCaP) cells. Gene expression alterations in PC3 and LNCaP cells treated with 15 muM DHC and 25 microM fisetin for 6 to 24 h were determined by oligonucleotide array. Amongst the most highly represented functional categories of genes altered by both compounds was the cell cycle category. In total, 100 cell cycle genes were altered by DHC and fisetin including 27 genes with key functions in G2/M phase that were downregulated by both compounds. Other functional categories altered included chromosome organization, apoptosis, and stress response. These results demonstrate the multiple mechanisms of antitumor activity of DHC and fisetin in prostate cancer cells in vitro.

Association of diet-induced hyperinsulinemia with accelerated growth of prostate cancer (LNCaP) xenografts

BACKGROUND

Prior research suggested that energy balance and fat intake influence prostate cancer progression, but the influence of dietary carbohydrate on prostate cancer progression has not been well characterized. We hypothesized that hyperinsulinemia resulting from high intake of refined carbohydrates would lead to more rapid growth of tumors in the murine LNCaP xenograft model of prostate cancer.

METHODS

Athymic mice were injected subcutaneously with LNCaP human prostate cancer cells and, when tumors were palpable, were randomly assigned (n = 20 per group) to high carbohydrate-high fat or low carbohydrate-high fat diets. Body weight and tumor volume were measured weekly. After 9 weeks, serum levels of insulin and insulin-like growth factor 1 (IGF-1) were measured by enzyme immunoassay. AKT activation and the levels of the insulin receptor in tumor cells were determined by immunoblotting. The in vitro growth response of LNCaP cells to serum from mice in the two treatment groups was measured based on tetrazolium compound reduction. All statistical tests were two-sided.

RESULTS

After 9 weeks on the experimental diets, mice on the high carbohydrate-high fat diet were heavier (mean body weight of mice on the high carbohydrate-high fat diet = 34 g versus 29.1 g on the low carbohydrate-high fat diet, difference = 4.9 g, 95% CI = 3.8 to 6.0 g; P = .003), experienced increased tumor growth (mean tumor volume in mice on high carbohydrate-high fat diet = 1695 versus 980 mm3 on low carbohydrate-high fat diet, difference = 715 mm3, 95% CI = 608 to 822 mm3; P<.001), and experienced a statistically significant increase in serum insulin and IGF-1 levels. Tumors from mice on the high carbohydrate-high fat diet had higher levels of activated AKT and modestly higher insulin receptor levels than tumors from mice on the low carbohydrate-high fat diet. Serum from mice on the high carbohydrate-high fat diet was more mitogenic for LNCaP cells in vitro than serum from mice fed the low carbohydrate-high fat diet.

CONCLUSION

A diet high in refined carbohydrates is associated with increased tumor growth and with activation of signaling pathways distal to the insulin receptor in a murine model of prostate cancer.

Novel antiproliferative flavonoids induce cell cycle arrest in human prostate cancer cell lines

Epidemiologic studies have demonstrated an inverse association between flavonoid intake and prostate cancer (PCa) risk. The East Asian diet is very high in flavonoids and, correspondingly, men in China and Japan have the lowest incidence of PCa worldwide. There are thousands of different naturally occurring and synthetic flavonoids. However, only a few have been studied in PCa. Our aim was to identify novel flavonoids with antiproliferative effect in PCa cell lines, as well as determine their effects on cell cycle. We have screened a representative subgroup of 26 flavonoids for antiproliferative effect on the human PCa (LNCaP and PC3), breast cancer (MCF-7), and normal prostate stromal cell lines (PrSC). Using a fluorescence-based cell proliferation assay (Cyquant), we have identified five flavonoids, including the novel compounds 2,2'-dihydroxychalcone and fisetin, with antiproliferative and cell cycle arresting properties in human PCa in vitro. Most of the flavonoids tested exerted antiproliferative effect at lower doses in the PCa cell lines compared to the non-PCa cells. Flow cytometry was used as a means to determine the effects on cell cycle. PC3 cells were arrested in G2/M phase by flavonoids. LNCaP cells demonstrated different cell cycle profiles. Further studies are warranted to determine the molecular mechanism of action of 2,2'-DHC and fisetin in PCa, and to establish their effectiveness in vivo.