The mTOR pathway affects proliferation and chemosensitivity of urothelial carcinoma cells and is upregulated in a subset of human bladder cancers

Genomics and Immunomics in the Treatment of Urothelial Carcinoma

Urothelial carcinoma is a complex cancer with genomic immunomic drivers that have prognostic and predictive treatment implications. Identifying potential targetable alterations via next-generation sequencing and RNA sequencing may allow for elucidation of such targets and exploitation with targeted therapeutics. The role of immunotherapy in treating urothelial carcinoma has shown benefit, but it is unclear in which patients immunotherapeutics have the highest yield. Continuing efforts into better identifying which patients may benefit most from targeted therapies, immunotherapies, and combination therapies may ultimately lead to improved outcomes for patients with this disease.

Lifestyle and Non-muscle Invasive Bladder Cancer Recurrence, Progression, and Mortality: Available Research and Future Directions

BACKGROUND:

A broad, comprehensive review of studies exploring associations between lifestyle factors and non-muscle invasive bladder cancer (NMIBC) outcomes is warranted to consolidate recommendations and identify gaps in research.

OBJECTIVE:

To summarize the literature on associations between lifestyle factors and clinical outcomes among patients with NMIBC.

METHODS:

PubMed was systematically queried for articles published through March 2019 regarding lifestyle factors and recurrence, progression, cancer-specific mortality, and all-cause mortality among patients with NMIBC.

RESULTS:

Notwithstanding many ambiguities, there is good-quality evidence suggesting a benefit of smoking avoidance/cessation, healthy body mass index (BMI), and type II diabetes mellitus prevention and treatment. Lactobacillus casei probiotic supplementation may reduce recurrence. There have been individual studies suggesting a benefit for uncooked broccoli and supplemental vitamin E as well as avoidance of supplemental vitamin B9, areca nut chewing, and a “Western diet” pattern high in fried foods and red meat. Additional studies do not suggest associations between NMIBC outcomes and use of fibrin clot inhibitors; insulin and other oral hypoglycemics; statins; supplemental selenium, vitamin A, vitamin C, and vitamin B6; fluid intake and intake of specific beverages (e.g., alcohol, coffee, green tea, cola); various dietary patterns (e.g., Tex-Mex, high fruit and vegetable, low-fat); and occupational and chemical exposures.

CONCLUSIONS:

Despite a myriad of publications on lifestyle factors and NMIBC, a need remains for research on unexplored associations (e.g., physical activity) and further studies that can elucidate causal effects. This would inform future implementation strategies for healthy lifestyle change in NMIBC patients.

Interaction of YAP1 and mTOR promotes bladder cancer progression

Yes‑associated protein 1 (YAP1) and mammalian target of rapamycin (mTOR) signaling pathways have been found to be deregulated in bladder cancer and accelerate the malignant progression of bladder cancer. However, the crosstalk between YAP1 and mTOR and its role in bladder cancer progression remains unclear. The aim of the present study was to investigate this crosstalk and the results revealed that the expression of YAP1 and mTOR was elevated in bladder cancer tissues compared with that in adjacent normal tissues. Knockdown of either mTOR or YAP1 with siRNA transfection significantly repressed the proliferation ability and induced apoptosis of HT‑1376 and J82 bladder cancer cells, particularly when YAP1 and mTOR were downregulated simultaneously. Upregulation of mTOR increased the mRNA and protein levels of YAP1 and enhanced its nuclear accumulation. In turn, YAP1 upregulation increased mTOR expression, reduced its protein degradation and increased its stability. In addition, immunofluorescence and Duolink assays demonstrated that YAP1 and mTOR were co‑localized in the nucleus. Immunoprecipitation assay demonstrated that the YAP1 protein was able to bind to the mTOR protein. Moreover, YAP1 combined with S‑phase kinase‑associated protein 2 (SKP2) and positively regulated its expression. Furthermore, the promotion of cell growth and inhibition of cell apoptosis induced by YAP1 overexpression were abolished when SKP2 was downregulated in HT‑1376 and J82 cells. Taken together, the findings of the present study indicated that the crosstalk between YAP1 and mTOR plays a pivotal role in accelerating the progression of bladder cancer, which may provide new insights into the role of the YAP1/mTOR axis in the occurrence and development of bladder cancer.

Rapamycin Prevents Surgery-Induced Immune Dysfunction in Patients with Bladder Cancer

The mechanistic target of rapamycin (mTOR) integrates environmental inputs to regulate cellular growth and metabolism in tumors. However, mTOR also regulates T-cell differentiation and activation, rendering applications of mTOR inhibitors toward treating cancer complex. Preclinical data support distinct biphasic effects of rapamycin, with higher doses directly suppressing tumor cell growth and lower doses enhancing T-cell immunity. To address the translational relevance of these findings, the effects of the mTOR complex 1 (mTORC1) inhibitor, rapamycin, on tumor and T cells were monitored in patients undergoing cystectomy for bladder cancer. MB49 syngeneic murine bladder cancer models were tested to gain mechanistic insights. Surgery-induced T-cell exhaustion in humans and mice and was associated with increased pulmonary metastasis and decreased PD-L1 antibody efficacy in mouse bladder cancer. At 3 mg orally daily, rapamycin concentrations were 2-fold higher in bladder tissues than in blood. Rapamycin significantly inhibited tumor mTORC1, shown by decreased rpS6 phosphorylation in treated versus control patients (P = 0.008). Rapamycin reduced surgery-induced T-cell exhaustion in patients, evidenced by a significant decrease in the prevalence of dysfunctional programmed death-1 (PD-1)-expressing T cells. Grade 3 to 4 adverse event rates were similar between groups, but rapamycin-treated patients had a higher rate of wound complications versus controls. In conclusion, surgery promoted bladder cancer metastasis and decreased the efficacy of postoperative bladder cancer immunotherapy. Low-dose (3 mg daily) oral rapamycin has favorable pharmacodynamic and immune modulating activity in surgical patients and has the potential to decrease surgery-induced immune dysfunction.

MicroRNA-495 Confers Increased Sensitivity to Chemotherapeutic Agents in Gastric Cancer via the Mammalian Target of Rapamycin (mTOR) Signaling Pathway by Interacting with Human Epidermal Growth Factor Receptor 2 (ERBB2)

Background

In recent years, the incidence of gastric cancer (GC) has been increasing worldwide. Emerging evidence shows that microRNAs (miRs) may be involved in the pathogenesis of GC. Thus, this study explored the mediatory role of miR-495 in GC chemosensitivity, and investigated the mechanism by which it affects the biological behaviors of GC cells via the mTOR signaling pathway.

Material/Methods

After GC and paracancerous tissue collection, the positive rate of ERBB2 and mTOR was evaluated by immunohistochemistry. Subsequently, the expression of miR-495, ERBB2, and mTOR was determined by RT-qPCR and Western blot analysis. Next, the targeting relationship between miR-495 and ERBB2 was confirmed by dual-luciferase reporter gene assay. In addition, chemosensitivity and proliferation were detected by MTT assay and apoptosis was assessed by flow cytometry.

Results

We found higher positive rates of ERBB2 and mTOR and decreased expression of miR-495 in GC tissues and showed that ERBB2 is the target gene of miR-495. Furthermore, we determined that overexpression of miR-495 and silencing of ERBB2 enhanced GC cell chemosensitivity and apoptosis, but inhibited GC cell proliferation. We also found that the effect of miR-495 inhibition was lost when ERBB2 was suppressed.

Conclusions

The key findings of our study demonstrate that the miR-495 exerts promotive effects on GC chemosensitivity via inactivation of the mTOR signaling pathway by suppressing ERBB2. The study provides reliable evidence supporting the use of miR-495 as a novel potential target in the chemotherapy of GC.

Sulforaphane for the chemoprevention of bladder cancer: molecular mechanism targeted approach

The clinical course for both early and late stage Bladder Cancer (BC) continues to be characterized by significant patient burden due to numerous occurrences and recurrences requiring frequent surveillance strategies, intravesical drug therapies, and even more aggressive treatments in patients with locally advanced or metastatic disease. For these reasons, BC is also the most expensive cancer to treat. Fortunately, BC offers an excellent platform for chemoprevention interventions with potential to optimize the systemic and local exposure of promising agents to the bladder mucosa. However, other than smoking cessation, there is a paucity of research that systematically examines agents for chemoprevention of bladder cancers. Adopting a systematic, molecular-mechanism based approach, the goal of this review is to summarize epidemiological, in vitro, and preclinical studies, including data regarding the safety, bioavailability, and efficacy of agents evaluated for bladder cancer chemoprevention. Based on the available studies, phytochemicals, specifically isothiocyanates such as sulforaphane, present in Brassicaceae or “cruciferous” vegetables in the precursor form of glucoraphanin are: (a) available in standardized formulations; (b) bioavailable- both systemically and in the bladder; (c) observed to be potent inhibitors of BC carcinogenesis through multiple mechanisms; and (d) without toxicities at these doses. Based on available evidence from epidemiological, in vitro, preclinical, and early phase trials, phytochemicals, specifically isothiocyanates (ITCs) such as sulforaphane (SFN) represent a promising potential chemopreventitive agent in bladder cancer.

Impact of oral hypoglycemic agents on mortality among diabetic patients with non-muscle-invasive bladder cancer: A populationbased analysis

INTRODUCTION

Non-muscle-invasive bladder cancer (NMIBC) accounts for 75-85% of all urothelial bladder cancers (UBC). Many UBC patients are also afflicted by diabetes mellitus (DM). It has been postulated that several oral hypoglycemic agents could impact disease-specific survival (DSS), but the data are sparse among NMIBC patients. Our primary objective was to evaluate the impact of metformin on DSS and overall survival (OS) in NMIBC patients.

METHODS

This is a retrospective, population-based study that used linked administrative databases to identify diabetic patients ≥66 years who were subsequently diagnosed with NMIBC in Ontario between 1992 and 2012. Cumulative use of metformin and other hypoglycemic agent were calculated before and after NMIBC diagnosis. DSS and OS were estimated using multivariable competing risk and Cox proportional hazards models, respectively.

RESULTS

A total of 1742 subjects were included in the study. After a median followup of 5.2 years, 1122 (64%) had died, including 247 (15%) deaths as a result of UBC. On multivariable analysis, cumulative duration of metformin use after NMIBC diagnosis did not appear to impact DSS (hazard ratio [HR] 1.1; 95% confidence interval [CI] 0.92-1.2), whereas glyburide use appeared to have a detrimental effect (HR 1.17; 95% CI 1.02-1.3). None of the other hypoglycemic agents had an impact on OS.

CONCLUSIONS

In this large, population-based study, we have provided further evidence that metformin use does not significantly impact DSS among diabetic patients diagnosed with NMIBC. However, our findings demonstrate that glyburide use inversely affects DSS. The detrimental effect of glyburide on DSS will require further validation.

Phosphorylated mTOR Expression Profiles in Human Normal and Carcinoma Tissues

Mammalian target of rapamycin (mTOR) is a key controller of cell growth and proliferation in normal tissues and solid tumors. In the present study, an immunohistochemical analysis of the expression pattern of phosphorylated mTOR (p-mTOR) was performed in human normal fetal and adult tissues and various carcinoma tissues. p-mTOR expression showed tissue and cell type specificity in normal and cancer tissues. In normal fetal and adult tissues, p-mTOR staining was observed in the intestinal crypt, intrahepatic bile ductule, pancreatic duct, distal nephron of the kidney, umbrella cell of urothelium, mesothelial cell, and choroid plexus. In cancer tissues, p-mTOR expression was higher in adenocarcinoma than in other types of cancers, in metastatic cancer than in primary cancer, and in the forefront of the infiltrating cancer cells. These results suggest that p-mTOR is implicated not only in cell proliferation but also in tubular morphogenesis in normal and cancer tissues. In addition, mTOR activation appears to be associated with cancer cell invasion and migration in solid tumors.

Rapamycin inhibits prostate cancer cell growth through cyclin D1 and enhances the cytotoxic efficacy of cisplatin

Prostate cancer is the most common malignancy in Western men and hormone refractory cancer (HRPC) kills most of the patients. Chemo-resistance is a major obstacle for the treatment of prostate cancer. Platinum-complexes have been used to treat a number of malignancies including prostate cancer. However, it has limited effect to prostate cancer and with significant toxicity at higher doses. In recent years, increasing numbers of new agents targeting cancer specific pathways have become available and with low toxic side-effects. Rapamycin (Sirolimus) is an mTORC1 inhibitor, which inhibits the PI3K/Akt/mTOR signaling pathway, which is commonly altered in prostate cancer. We determined the expression of cyclin D1 and phosphorylated-mTOR proteins in association with the response to rapamycin in two androgen sensitive (22RV1 and LNCaP) and two androgen independent (DU145 and PC3) prostate cancer cell lines and found that the base-line and changes of cyclin D1 level, but not the expression level of p-mTOR, correlated with rapamycin sensitivity. We evaluated the cell killing effect of combined rapamycin and cisplatin treatment and showed that the combination had a more than additive effect in both androgen dependent and independent prostate cancer cells, which may be partially explained by the reduction of cyclin D1 expression by rapamycin. We also evaluated a range of combined treatment schedules, simultaneously or sequentially and found that continuous rapamycin treatment after a short cisplatin exposure was effective. The clinical application of these findings for prostate cancer treatment should be further investigated.

Intravesical dual PI3K/mTOR complex 1/2 inhibitor NVP-BEZ235 therapy in an orthotopic bladder cancer model

NVP-BEZ235 is an inhibitor of both phosphatidylinositol 3-kinase (PI3K) and mammalian target of rapamycin complex 1/2 (mTORC1/2), and its antitumor activity is expected to be higher than that of mTORC1 inhibitors because it inhibits the upregulation of pAkt through mTORC2. We examined the efficacy of intravesical NVP-BEZ235 therapy in the treatment of bladder cancer using an orthotopic bladder cancer model. The cytotoxic effects of various concentrations of NVP-BEZ235 in MBT-2 cells were examined using a WST assay. The expression of pAkt, pS6 and p4EBP1 was evaluated in MBT-2 cells treated with NVP-BEZ235 using western blotting. Orthotopic models were established by implanting MBT-2 cells into the bladders of female C3H/He mice. We assigned C3H/He mice to 2 groups: a control group treated with vehicle control (n=15), and a group intravesically administered 40 µM (18.78 mg/l) of NVP-BEZ235 (n=15). NVP-BEZ235 inhibited the viability of MBT-2 cells in a dose-dependent manner. Furthermore, the expression of pAkt, pS6, and p4EBP1 was inhibited in NVP-BEZ235-treated MBT-2 cells. Bladder weights were significantly lower in the NVP-BEZ235-treated group than in the control group (P<0.05). An analysis of the tumor tissues revealed that the NVP-BEZ235 treatment strongly reduced pAkt, pS6 and p4EBP1 levels. An immunohistochemical analysis showed that NVP-BEZ235 significantly inhibited the expression of pS6. Intravesically administered NVP-BEZ235 exerted significant antitumor effects in the orthotopic bladder cancer model by inhibiting the PI3K/Akt/mTOR pathway. The intravesical instillation of a dual PI3K/mTORC1/2 inhibitor may represent a novel therapy for the treatment of bladder cancer.

Targeting Hsp90 in urothelial carcinoma

Urothelial carcinoma, or transitional cell carcinoma, is the most common urologic malignancy that carries significant morbidity, mortality, recurrence risk and associated health care costs. Despite use of current chemotherapies and immunotherapies, long-term remission in patients with muscle-invasive or metastatic disease remains low, and disease recurrence is common. The molecular chaperone Heat Shock Protein-90 (Hsp90) may offer an ideal treatment target, as it is a critical signaling hub in urothelial carcinoma pathogenesis and potentiates chemoradiation. Preclinical testing with Hsp90 inhibitors has demonstrated reduced proliferation, enhanced apoptosis and synergism with chemotherapies and radiation. Despite promising preclinical data, clinical trials utilizing Hsp90 inhibitors for other malignancies had modest efficacy. Therefore, we propose that Hsp90 inhibition would best serve as an adjuvant treatment in advanced muscle-invasive or metastatic bladder cancers to potentiate other therapies. An overview of bladder cancer biology, current treatments, molecular targeted therapies, and the role for Hsp90 inhibitors in the treatment of urothelial carcinoma is the focus of this review.

Histopathological assessment of inflammation and expression of inflammatory markers in patients with ketamine-induced cystitis

The aim of the current study was to evaluate the histopathological features of inflammation and the expression levels of inflammatory markers in tissue samples from patients with ketamine-induced cystitis. Bladder biopsy samples for histological analysis were obtained from 23 patients (18 men and 5 women) with a self-reported history of ketamine use and who were treated for cystitis at the Tri-Service General Hospital of Taipei, Taiwan. Immunohistochemical staining for cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), matrix metallopeptidase-9 (MMP-9), mammalian target of rapamycin (mTOR), and phosphorylated 40S ribosomal protein S6 (Phos-S6) was performed. The results revealed urothelial atypia in all patients, and intravascular eosinophil accumulation in 22 patients. Histopathological features included denuded urothelial mucosa, ulceration, collagen deposition, smooth muscle degeneration and vessel proliferation. Tissue samples were immunopositive for all of the inflammation markers, including the urothelium, vessel walls, and smooth muscle. COX-2 staining revealed a significant difference between the inflammatory levels in the urothelium and smooth muscle, and iNOS staining differed significantly between inflammatory levels in smooth muscle (p=0.029). A positive correlation was observed between the percentage of Phos-S6-positive cells and the levels of inflammation in the urothelium. These results add to the descriptive literature on the histopathological aspects of ketamine-induced cystitis, emphasizing the inflammatory nature and a possible role for proteins such as COX-2, iNOS and Phos-S6 in the degree of inflammation.

Phospho-mTOR in non-tumour and tumour bladder urothelium: Pattern of expression and impact on urothelial bladder cancer patients

Urothelial bladder carcinoma (UBC) is heterogeneous in its pathology and clinical behaviour. Evaluation of prognostic and predictive biomarkers is necessary, in order to produce personalised treatment options. The present study used immunohistochemistry to evaluate UBC sections containing tumour and non-tumour areas from 76 patients, for the detection of p-mTOR, CD31 and D2-40 (blood and lymphatic vessels identification, respectively). Of the non-tumour and tumour sections, 36 and 20% were scored positive for p-mTOR expression, respectively. Immunoexpression was observed in umbrella cells from non-tumour urothelium, in all cell layers from non-muscle-invasive (NMI) tumours (including expression in superficial cells), and in spots of cells from muscle-invasive (MI) tumours. Positive expression decreased from non-tumour to tumour urothelium, and from pT1/pTis to pT3/pT4 tumours; however, the few pT3/pT4 positive cases had worse survival rates, with 5-year disease-free survival being significantly lower. Angiogenesis occurrence was impaired in pT3/pT4 tumours that did not express p-mTOR. In conclusion, p-mTOR expression in non-tumour umbrella cells is likely a reflection of their metabolic plasticity, and extension to the inner layers of the urothelium in NMI tumours is consistent with an enhanced malignant potential. The expression in cell spots in a few MI tumours and absence of expression in the remaining tumours is intriguing and requires further research. Additional studies regarding the up- and downstream effectors of the mTOR pathway should be conducted.

Current animal models of bladder cancer: Awareness of translatability (Review)

Experimental animal models are crucial in the study of biological behavior and pathological development of cancer, and evaluation of the efficacy of novel therapeutic or preventive agents. A variety of animal models that recapitulate human urothelial cell carcinoma have thus far been established and described, while models generated by novel techniques are emerging. At present a number of reviews on animal models of bladder cancer comprise the introduction of one type of method, as opposed to commenting on and comparing all classifications, with the merits of a certain method being explicit but the shortcomings not fully clarified. Thus the aim of the present study was to provide a summary of the currently available animal models of bladder cancer including transplantable (which could be divided into xenogeneic or syngeneic, heterotopic or orthotopic), carcinogen-induced and genetically engineered models in order to introduce their materials and methods and compare their merits as well as focus on the weaknesses, difficulties in operation, associated problems and translational potential of the respective models. Findings of these models would provide information for authors and clinicians to select an appropriate model or to judge relevant preclinical study findings. Pertinent detection methods are therefore briefly introduced and compared.

Incidence of bladder cancer in patients with type 2 diabetes treated with metformin or sulfonylureas

OBJECTIVE

Previous studies evaluating the effect of metformin on cancer risk have been impacted by time-related biases. To avoid these biases, we examined the incidence of bladder cancer in new users of metformin and sulfonylureas (SUs).

RESEARCH DESIGN AND METHODS

This cohort study included 87,600 patients with type 2 diabetes in The Health Improvement Network database. Use of metformin or an SU was treated as a time-dependent variable. Cox regression-generated hazard ratios (HRs) compared metformin use with SU use, adjusted for age, sex, smoking, obesity, and HbA1c level.

RESULTS

We identified 196 incident bladder cancers in the metformin cohort and 66 cancers in the SU cohort. Use of metformin was not associated with decreased bladder cancer risk (HR 0.81 [95% CI 0.60-1.09]). This association did not differ by sex (P for interaction = 0.20). We observed no association with duration of metformin relative to SU use (3 to <4 years of use: 0.57 [0.25-1.34]; 4 to <5 years of use: 0.93 [0.30-2.85; ≥5 years of use: 1.18 [0.44-3.19]; P for trend = 0.26).

CONCLUSIONS

Use of metformin is not associated with a decreased incidence of bladder cancer. Similar methods should be used to study other cancers that have previously been identified as potentially preventable with metformin.

The combination of an mTORc1/TORc2 inhibitor with lapatinib is synergistic in bladder cancer in vitro

OBJECTIVE

To examine the ability of dual mTORc1/c2 inhibitors in conjunction with lapatinib to function in a synergistic manner to inhibit cell proliferation and anchorage-independent growth in bladder cancer cell lines.

MATERIALS AND METHODS

We examined patient tumor samples for overexpression of pS6, p4EBP1, pAkt, and phosphorylated epidermal growth factor receptor (pEGFR) using a tissue microarray containing 84 cases. Three bladder cancer cell lines, T24, HT1376, and UM-UC-3, were analyzed for cell proliferation after treatment with mTORc1/c2 inhibitors OSI-027 or PP242. Western blots were used to verify that the drugs were inhibiting phosphorylation of target proteins within the mTOR pathway, and they were compared with rapamycin inhibition. We also analyzed cell proliferation and anchorage-independent growth after treatment with OSI-027 and lapatinib in combination. PARP cleavage and autophagic flux were measured by examining levels of LC3B and p62 by western blotting.

RESULTS

Tumor samples show increased expression of pEGFR (38% vs. 8%) and HER2 (38% vs. 4%) and decreased expression of pAkt S473 (7.5% vs. 29%) and pAkt T308 (50% vs. 84%) relative to normal tissue. Significant differences between normal and tumor samples for staining with pEGFR (P = 0.0188), HER 2 (P = 0.0017), pATK S473 (P = 0.0128), and pAkt T308 (P = 0.0015) is observed. Expression of proteins within the EGFR/HER2 pathway or within the mTOR pathway is correlated. No correlation was found between staining and tumor stage. OSI-027 and PP242 diminish cell proliferation in all 3 cell lines with IC50 values ranging from 0.63 to 17.95µM. Both drugs inhibit phosphorylation of both mTORc1 and mTORc2 pathway components. OSI-027 and lapatinib inhibit cell proliferation and anchorage-independent growth in a synergistic manner. One cell line exhibited apoptosis in response to combination drug treatment, whereas the other 2 cell lines have increased levels of autophagy indicative of resistance to apoptosis.

CONCLUSIONS

The combination of OSI-027 and lapatinib results in antitumor synergy and further exploration of this combination should be undertaken.

Patient-derived xenografts reveal limits to PI3K/mTOR- and MEK-mediated inhibition of bladder cancer

BACKGROUND

Metastatic bladder cancer is a serious condition with a 5-year survival rate of approximately 14 %, a rate that has remained unchanged for almost three decades. Thus, there is a profound need to identify the driving mutations for these aggressive tumors to better determine appropriate treatments. Mutational analyses of clinical samples suggest that mutations in either the phosphoinositide-3 kinase (PI3K)-AKT-mammalian target of rapamycin (mTOR) or RAS/MEK/ERK pathways drive bladder cancer progression, although it remains to be tested whether the inhibition of either (or both) of these pathways can arrest PI3K/mTOR- or Ras-driven proliferation.

METHODS

Herein, we used several bladder cancer cell lines to determine drug sensitivity according to genetic background and also studied mouse models of engrafted UM-UC-3 cells and patient-derived xenografts (PDXs) to test PI3K/mTOR and MEK inhibition in vivo.

RESULTS

Inhibition of these pathways utilizing PF-04691502, a PI3K and mTOR inhibitor, and PD-0325901, a MEK inhibitor, slowed the tumor growth of PDX models of bladder cancer. The growth inhibitory effect of combination therapy was similar to that of the clinical maximum dose of cisplatin; mechanistically, this appeared to predominantly occur via drug-induced cytostatic growth inhibition as well as diminished vascular endothelial growth factor secretion in the tumor models. Kinase arrays of tumors harvested after treatment demonstrated activated p53 and Axl as well as STAT1 and STAT3.

CONCLUSION

Taken together, these results indicate that clinically relevant doses of PF-04691502 and PD-0325901 can suppress bladder tumor growth in PDX models, thus offering additional potential treatment options by a precision medicine approach.

Expression of cyclin d1 and its association with disease characteristics in bladder cancer

AIM

Invasive urothelial carcinoma of the bladder (UCB) is characterized by alterations in cell-cycle regulatory pathways. Defects in the expression of cyclin D1, a key cell-cycle regulator, have been implicated in progression of various types of cancer. In the present study, we investigated whether cyclin D1 expression is associated with clinicopathological parameters and whether it has any potential prognostic value in determining risk of UCB recurrence.

PATIENTS AND METHODS

Tissue microarrays containing bladder cancer specimens (n=212) and adjacent normal bladder tissues (n=131) were immunostained using an antibody against cyclin D1. The association between cyclin D1 and clinicopathological parameters including stage, lymph node metastasis, and disease-free survival, were evaluated. Cyclin D1 mRNA expression data from human normal bladder (n=14) and cancer specimens (n=28) were extracted from the public Oncomine database.

RESULTS

Cyclin D1 mRNA and protein expression were significantly higher in UCB compared to adjacent non-malignant bladder tissue (for mRNA p=0.003, for protein p=0.001). Cyclin D1 protein expression was significantly higher in non-invasive tumors than in muscle-invasive UCB (p=0.016). Among patients with muscle-invasive UCB, increased cyclin D1 expression in tumor cells significantly correlated with lymph node metastasis (p<0.001), and there was a trend of cyclin D1 together with lymph node positivity to be associated with disease recurrence (p=0.678). Loss of nuclear cyclin D1 expression in tumor cells was likewise significantly associated with the presence of lymph node metastasis (p<0.001).

CONCLUSION

Altered expression of cyclin D1 is associated with lymph node metastasis and risk of UCB recurrence. Cyclin D1 expression may therefore have clinical value as a prognostic marker and potential therapeutic target.

Temsirolimus improves cytotoxic efficacy of cisplatin and gemcitabine against urinary bladder cancer cell lines

OBJECTIVES

To analyze the cytotoxic action of temsirolimus using 3 established human bladder cancer cell lines and to assess whether temsirolimus potentiates the anticancer activity of gemcitabine and cisplatin.

METHODS

Temsirolimus (500, 1,000, 2,000, and 4,000 nM), in isolation, and combined with gemcitabine (100 nM) and cisplatin (2.5 µg/ml), was given to 5637, T24, and HT1376 bladder cancer cell lines. Cell proliferation, autophagy, early apoptosis, and cell cycle distribution were analyzed after a 72-hour period. The expression of mammalian target of rapamycin baseline, Akt, and their phosphorylated forms, before and after treatment with temsirolimus, was evaluated by immunoblotting.

RESULTS

Temsirolimus slightly decreased the bladder cancer cell proliferation in all 3 cell lines. No significant differences in the expression of mammalian target of rapamycin, Akt, and their phosphorylated forms because of temsirolimus exposure were found in the 3 cell lines. As part of a combined regime along with gemcitabine, and especially with cisplatin, there was a more pronounced antiproliferative effect. This pattern of response was similar to the other parameters analyzed (increased autophagy and apoptosis). Also, in the combined regime, an enhanced cell cycle arrest in the G0/G1 phase was observed. The non-muscle invasive 5637 bladder cancer cell line was most sensitive to both combinations.

CONCLUSIONS

Temsirolimus makes a moderate contribution in terms of cell proliferation, apoptosis, and autophagy. However, it does potentiate the activity of gemcitabine and particularly cisplatin. Therefore, cisplatin- or gemcitabine-based chemotherapy regimen used in combination with temsirolimus to treat bladder cancer represents a novel and valuable treatment option, which should be tested for future studies in urinary bladder xenograft models.

High levels of phosphatase and tensin homolog expression are associated with tumor progression, tumor recurrence, and systemic metastases in pT1 urothelial carcinoma of the bladder: a tissue microarray study of 156 patients treated by transurethral resection

OBJECTIVE

To evaluate immunohistochemical expression of phosphatase and tensin homolog (PTEN) and mammalian target of rapamycin (mTOR) pathway members in pT1 urothelial carcinomas treated by transurethral resection and to determine if immunohistochemistry can be used to predict prognosis.

METHODS

Formalin-fixed, paraffin-embedded tissue samples from 156 patients with pT1 urothelial carcinoma treated by transurethral resection were used to build 5 tissue microarrays. Tissue microarray sections were stained for PTEN, phosphorylated (phos)-AKT, phos-mTOR, phos-S6, eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1), and phos-4EBP1. Patients were monitored after initial treatment (mean, 22.5; median, 16; range, 3-108 months) to detect tumor recurrence, tumor progression, or systemic metastases.

RESULTS

During follow-up, 101 patients (65%) showed tumor recurrence, 57 showed tumor progression (37%), and 18 showed systemic metastases (12%). Patients with ≥2 lesions at the initial workup had higher proportions and higher hazard ratios of tumor recurrence, tumor progression, and systemic metastases. Complete loss of PTEN expression was observed in 6 patients (4%), and >80% of the mTOR pathway members showed at least focal positivity. Proportions of tumors with higher levels of PTEN immunohistochemical expression were higher in patients with tumor recurrence (P=.001), tumor progression (P=.05), and systemic metastases (P=.001). Proportions of tumors with lower phos-S6 and low phos-4EBP1 levels were higher in patients with tumor recurrence (P≤.05). Proportions were similar for the remaining biomarkers.

CONCLUSION

Higher levels of PTEN immunohistochemical expression were associated with higher rates of tumor recurrence, tumor progression, and systemic metastases in patients with pT1 urothelial carcinomas treated by transurethral resection.

Antitumor effects of rapamycin in pancreatic cancer cells by inducing apoptosis and autophagy

Rapamycin (Rapa), an inhibitor of mammalian target of Rapamycin (mTOR), is an immunosuppressive agent that has anti-proliferative effects on some tumors. This study aims to investigate the effects of Rapa suppressing proliferation of pancreatic carcinoma PC-2 cells in vitro and its molecular mechanism involved in antitumor activities. MTT assays showed that the inhibition of proliferation of PC-2 cells in vitro was in a time- and dose-dependent manner. By using transmission electron microscopy, apoptosis bodies and formation of abundant autophagic vacuoles were observed in PC-2 cells after Rapa treatment. Flow cytometry assays also showed Rapa had a positive effect on apoptosis. MDC staining showed that the fluorescent density was higher and the number of MDC-labeled particles in PC-2 cells was greater in the Rapa treatment group than in the control group. RT-PCR revealed that the expression levels of p53, Bax and Beclin 1 were up-regulated in a dose-dependent manner, indicating that Beclin 1 was involved in Rapa induced autophagy and Rapa induced apoptosis as well as p53 up-regulation in PC-2 cells. The results demonstrated that Rapa could effectively inhibit proliferation and induce apoptosis and autophagy in PC-2 cells.

A comprehensive immunohistochemical and molecular approach to the PI3K/AKT/mTOR (phosphoinositide 3-kinase/v-akt murine thymoma viral oncogene/mammalian target of rapamycin) pathway in bladder urothelial carcinoma

What's known on the subject? and What does the study add? A few published studies investigating single or various PI3K/AKT/mTOR signalling components have produced inconsistent results. Moreover, PI3K regulatory subunit p85a and activated p70S6K expression levels have not been previously examined in urothelial carcinoma (UC). The present study addresses simultaneously all key members of PI3K/AKT/mTOR signalling cascade supporting a differential implication of PI3K/AKT/mTOR pathway components in urothelial tumorigenesis. Furthermore, we propose p-4E-BP1 as a potential prognostic marker in UC, which might assist the selection of patients more likely to benefit from chemotherapy regimens based on PI3K/AKT/mTOR pathway inhibition. Finally, the present study indicates PIK3CA/AKT1 mutational status as a potential predictive marker for time-to-recurrence.

OBJECTIVE

• To perform a comprehensive simultaneous assessment of all key members of phosphoinositide 3-kinase/v-akt murine thymoma viral oncogene/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway along with AKT homolog 1 (AKT1) and PIK3 catalytic alpha polypeptide (PIK3CA) mutations in bladder urothelial carcinoma (UC). • Published information is limited to a few studies looking into single or various combinations of members of this pathway with inconsistent results. In particular the expression status of phosphorylated (p-)p70S6 kinase (p70S6K) and p85a subunit of PI3K has not been tested in UC.

PATIENTS AND METHODS

• Paraffin-embedded transurethral resection tissue from 113 patients with UC was investigated for the association of p85aPI3K, p-AKT, p-mTOR, p-p70S6K and p-4E-BP1 (eukaryotic initiation factor 4E-binding protein 1) expression status, as well as PIK3CA and AKT1 mutations with p-extracellular signal-regulated kinase 1/2 (ERK1/2), fibroblast growth factor receptor 3 (FGFR3), pathological features, recurrence and cancer-specific survival.

RESULTS

• With the exception of p-p70S6K, all others components of the PI3K/AKT/mTOR pathway were upregulated in UCs as compared with normal urothelium. • p-mTOR expression strongly correlated with its upstream p-AKT and marginally with its downstream p-p70S6K. p85aPI3K and p-ERK1/2 levels were also marginally correlated. • PIK3CA and AKT1 mutations were distinctly uncommon and mutually exclusive, without any association with pathological features. However, the presence of AKT1 mutations was associated with increased FGFR3 levels and was restricted to p85aPI3K immunonegative cases, whereas PIK3CA mutant cases had marginally lower p85aPI3K levels. • The presence of PIK3CA single or combined with AKT1 mutations was associated with shorter recurrence-free survival in univariate survival analysis. An inverse relationship was established between p-4E-BP1 immunopositivity and histological grade or T category, as well as between p-p70S6K levels and T category, the latter relationship being of marginal significance. • p-4E-BP1 nuclear expression was marginally associated with the presence of lymphovascular invasion and adversely affected survival in multivariate, but not in univariate analysis.

CONCLUSIONS

• PI3K/AKT/mTOR signalling components appear to be differentially implicated in urothelial tumorigenesis and, with the exception of p85aPI3K, are unrelated to the PIK3CA or AKT1 mutational status. • Our findings propose p-4E-BP1 as a potential prognostic marker in UC independent of its association with pathological features, which might assist the selection of patients more likely to benefit from PI3K/AKT/mTOR axis inhibition. • PIK3CA/AKT1 mutational status may have a place in the prediction of time-to-recurrence.

Autophagy limits the cytotoxic effects of the AKT inhibitor AZ7328 in human bladder cancer cells

BACKGROUND

Mutations that activate the PI3K/AKT/mTOR pathway are relatively common in urothelial (bladder) cancers, but how these pathway mutations affect AKT dependency is not known. We characterized the relationship between AKT pathway mutational status and sensitivity to the effects of the selective AKT kinase inhibitor AZ7328 using a panel of 12 well-characterized human bladder cancer cell lines.

METHODS

Sequenome DNA sequencing was performed to identify mutations in a panel of 12 urothelial cancer cell lines. Drug-induced proliferative inhibition and apoptosis were quantified using MTT assays and propidium iodide staining with FACS analyses. Protein activation via phosphorylation was measured by immunoblotting. Autophagy was measured by LC3 immunofluorescence and immunoblotting.

RESULTS

AZ7328 inhibited proliferation and AKT substrate phosphorylation in a concentration-dependent manner but had minimal effects on apoptosis. Proliferative inhibition correlated loosely with the presence of activating PIK3CA mutations and was strengthened in combination with the mTOR inhibitor rapamycin. AZ7328 induced autophagy in some of the lines, and in the cells exposed to a combination of AZ7328 and chemical autophagy inhibitors apoptosis was induced.

CONCLUSIONS

The cytostatic effects of AZ7328 correlate with PIK3CA mutations and are greatly enhanced by dual pathway inhibition using an mTOR inhibitor. Furthermore, AZ7328 can interact with autophagy inhibitors to induce apoptosis in some cell lines. Overall, our results support the further evaluation of combinations of PI3K/AKT/mTOR pathway and autophagy inhibitors in pre-clinical in vivo models and ultimately in patients with PIK3CA mutant bladder cancers.

Urothelial tumor initiation requires deregulation of multiple signaling pathways: implications in target-based therapies

Although formation of urothelial carcinoma of the bladder (UCB) requires multiple steps and proceeds along divergent pathways, the underlying genetic and molecular determinants for each step and pathway remain undefined. By developing transgenic mice expressing single or combinatorial genetic alterations in urothelium, we demonstrated here that overcoming oncogene-induced compensatory tumor barriers was critical for urothelial tumor initiation. Constitutively active Ha-ras (Ras*) elicited urothelial hyperplasia that was persistent and did not progress to tumors over a 10 months period. This resistance to tumorigenesis coincided with increased expression of p53 and all pRb family proteins. Expression of a Simian virus 40 T antigen (SV40T), which disables p53 and pRb family proteins, in urothelial cells expressing Ras* triggered early-onset, rapidly-growing and high-grade papillary UCB that strongly resembled the human counterpart (pTaG3). Urothelial cells expressing both Ras* and SV40T had defective G(1)/S checkpoint, elevated Ras-GTPase and hyperactivated AKT-mTOR signaling. Inhibition of the AKT-mTOR pathway with rapamycin significantly reduced the size of high-grade papillary UCB but hyperactivated mitogen-activated protein kinase (MAPK). Inhibition of AKT-mTOR, MAPK and STAT3 altogether resulted in much greater tumor reduction and longer survival than did inhibition of AKT-mTOR pathway alone. Our studies provide the first experimental evidence delineating the combinatorial genetic events required for initiating high-grade papillary UCB, a poorly defined and highly challenging clinical entity. Furthermore, they suggest that targeted therapy using a single agent such as rapamycin may not be highly effective in controlling high-grade UCB and that combination therapy employing inhibitors against multiple targets are more likely to achieve desirable therapeutic outcomes.

Effects of mTOR inhibitor everolimus (RAD001) on bladder cancer cells

PURPOSE

We investigated the effect of the mTOR inhibitor RAD001 (everolimus) on human bladder cancer (BC) cells in vitro and in vivo.

EXPERIMENTAL DESIGN

The effect of RAD001 on the growth of UM-UC-3, UM-UC-6, UM-UC-9, and UM-UC-14 BC cells were assessed by crystal violet and [(3)H]thymidine incorporation assays. Flow cytometric cell-cycle analyses were done to measure the apoptotic cell fraction. Protein synthesis was measured using tritium-labeled leucine incorporation assays. The effects of RAD001 on the mTOR pathway were analyzed by Western blotting. To test the effects of RAD001 in vivo, UM-UC-3, UM-UC-6, and UM-UC-9 cells were subcutaneously implanted into nude mice. Tumor-bearing mice were treated orally with RAD001 or placebo. Tumors were harvested for immunohistochemical analysis.

RESULTS

In vitro, RAD001 transiently inhibited BC cell growth in a dose-dependent manner. This effect was augmented by re-treatment of cells after 3 days. UM-UC-14 cells were the most sensitive to RAD001, whereas UM-UC-9 cells were the least sensitive. After re-treatment with RAD001, only sensitive cell lines showed G(1)-phase arrest, with no evidence of apoptosis. RAD001 significantly inhibited the growth of tumors that were subcutaneously implanted in mice. Inhibition of protein synthesis through the S6K and 4EBP1 pathways seems to be the main mechanism for the RAD001-induced growth inhibition. However, inhibition of angiogenesis was the predominant mechanism of the effect of RAD001 on UM-UC-9 cells.

CONCLUSIONS

The mTOR inhibitor RAD001 inhibits growth of BC cells in vitro. RAD001 is effective in treating BC tumors in an in vivo nude mouse model despite the heterogeneity of in vitro responses.