Metformin for the Prevention of Bladder Cancer Recurrence: Is it Effective?

The Effect of Metformin on Bladder Cancer Incidence and Outcomes: A Systematic Review and Meta-Analysis

BACKGROUND

Effective oral treatment options for urothelial bladder cancer (BC) are lacking. Metformin, the most frequently used oral drug in type II diabetes mellitus, has putative anticancer properties and could, therefore, influence BC incidence and treatment outcomes. We systematically reviewed the current literature regarding the effect of metformin on BC incidence and oncological outcomes in non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC).

METHODS

This review was conducted according to the PRISMA guidelines. Literature was gathered through a systematic search in PubMed/Medline, EMBASE and the Cochrane library. Risk of bias was determined using the Cochrane risk-of-bias tool for randomized trials and the Newcastle-Ottawa Scale for non-randomized trials. Hazard ratios (HRs) were extracted and pooled in a random-effects meta-analysis.

RESULTS

We reviewed 13 studies, including 3,315,320 patients, considering the risk of developing BC after metformin exposure and 9 studies, including 4,006 patients, on oncological outcomes of patients with BC. Metformin did not affect BC incidence (HR 0.97, 95% CI 0.87 -1.09) or oncological outcomes for NMIBC but did show a reduced risk of recurrence (HR 0.52, 95% CI 0.32 -0.84), cancer-specific mortality (HR 0.58, 95% CI 0.43 -0.78) and overall mortality (HR 0.66, 95% CI 0.47 -0.92) in MIBC.

CONCLUSIONS

The role of metformin in the prevention and treatment of BC in patients remains unclear. Although a beneficial effect of metformin on treatment outcomes of certain stages of BC may exist, a definitive conclusion cannot be drawn. Prospective clinical trials are needed to assess the efficacy of metformin for BC treatment.

Metformin addition to androgen deprivation therapy effect on cancer prostate patients with type 2 diabetes

AIMS

Patients with prostate cancer (PC) have a higher rate of non-cancer mortality than cancer-related, which could be partially attributed to the treatment they receive. We aimed to evaluate the effect of metformin addition to androgen deprivation therapy (ADT) among cancer prostate patients with type 2 DM.

METHODOLOGY

This prospective, two-arm study included 95 PC patients with type 2 DM who had ADT. The patients were divided into 2 groups: the Metformin group includes 48 patients and the non-metformin group includes 47 patients. We compared the anthropometric, diabetic status; tumour status, survival rate, and biochemical relapse between metformin and non-metformin groups.

RESULTS

We observed significant differences in fold changes of anthropometric parameters including weight, BMI, and waist circumference between both groups. We found significant differences in fold change of PSA levels in metformin groups in comparison with non-metformin groups. Overall survival comparison between metformin users and non-users showed better statistically insignificant survival in the metformin users group. We observed a significantly lower relapse rate in the metformin group in comparison with the non-metformin.

CONCLUSION

Metformin could decrease some of the unfavourable metabolic consequences of ADT. Moreover, Metformin could enhance the tumour-suppressive effect of ADT and decrease the PSA relapse rate.

Metformin targets a YAP1-TEAD4 complex via AMPKα to regulate CCNE1/2 in bladder cancer cells

Background

Metformin has been reported to function as the anti-tumor inhibiting the growth of different types of cancers, including bladder cancer. But there are few reports on the roles of Yap1, the key molecule of Hippo pathway, in the metformin induced inhibition of bladder cancer (BLCA). We are wondering if the inhibitory effect of metformin on bladder cancer is fulfilled via Yap1 and exploring the related mechanism.

Methods

MTS and colony formation assays were used to explore the cellular viabilities and proliferation of BLCA cells challenged by metformin at different concentrations, in vitro. Flow Cytometry (FCM) was used to analyze the cell cycle and the cellular apoptosis of the BLCA cells. Western Blot was performed to detect the expressions of AMPKα, Yap1, CCND1, CCNE1/2 and CDK2/4/6 in the metformin-treated BLCA cell lines. RNAi method was used for the related genetic functional analysis. The relationships among Yap1, TEADs and CCNE1/2 were predicted and evaluated using bioinformatics, dual-luciferase reporter and co-immunoprecipitation (Co-IP) assays. For in vivo experiments, a xenograft model was used to investigate the effects of metformin on the proliferation of BLCA cells. And Immunohistochemistry (IHC) assay was performed to assess the expressions of CCNE1/2 and Yap1 proteins in the tumor tissues from the model.

Results

Metformin could inhibit the proliferation of the BLCA cells via inducing the G1 cell cycle arrest without apoptosis. And metformin upregulated the phosphorylated AMPKα and decreased the expressions of Yap1 and CCND1, CCNE1/2 and CDK4/6. AMPK inhibition by compound C (CC) restored the cell proliferation and the G1 cell cycle arrest induced by metformin, in vivo. Knockdown of YAP1 inhibited the proliferation of BLCA cells and caused the cell cycle arrest at G1 phase by decreasing the expressions of CCNE1/2 and other G1 phase related molecules, which has been restored by the Yap 5SA mutant. Bioinformatics analysis showed that trans-factor TEAD4 was highly expressed and positively associated with the expressions of CCNE1 and CCNE2 in BLCA and only TEAD4 was precipitated by Yap1 in the BLCA cells. Further studies demonstrated that Yap1 positively regulated both CCNE1 and CCNE2 expressions via forming complex with TEAD4. Furthermore, we observed that metformin inhibited the cell proliferation by decreasing the expressions of Yap1 and both CCNE1 and CCNE2 in xenograft model.

Conclusions

The results of our study reveal a new potential regulatory pathway in which metformin inhibits cell proliferation via AMPKα/Yap1/TEAD4/CCNE1/2 axis in BLCA cells, providing new insights into novel molecular therapeutic targets for BLCA.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1346-1) contains supplementary material, which is available to authorized users.

Expression of miR-490-5p, miR-148a-3p and miR-608 in bladder cancer and their effects on the biological characteristics of bladder cancer cells

Changes in the expression of miR-490-5p, miR-148a-3p and miR-608 in bladder cancer tissues were studied. A total of 30 patients with bladder cancer who had surgical resection in the Hunan Provincial People's Hospital (Changsha, China) from April 2015 to August 2016 were selected. RT-qPCR was used to detect the expression levels of miR-490-5p, miR-148a-3p and miR-608. The expression vectors of miR-490-5p, miR-148a-3p and miR-608 were respectively transfected and divided into three groups: blank cell group, gene transfection group (groups A-C) and negative transfection group (NC group). CCK8 was used to detect cell proliferation and flow cytometry was used to detect the condition of apoptosis of each group, and the Transwell chamber was used to detect the invasion ability of the cells. After the transfection, the expression level of miR-490-5p in group A was significantly higher than that in the NC and blank groups, and the expression level of miR-148a-3p in group B was significantly higher than that in the NC and blank groups. The expression level of miR-608 in group C was significantly higher than that in the NC and blank groups (P<0.001). The survival rates of the cells in groups A-C were significantly lower than those in the NC and blank groups at 48 and 72 h (P<0.001). After the transfection, the number of invasive cells and the apoptosis rates in groups A-C were significantly higher than those in the NC and blank groups (P<0.05). miR-490-5p, miR-148a-3p and miR-608 promoted proliferation of bladder cancer T24 cells and inhibited apoptosis of the cells and showed potential to become a new target for the future treatment of bladder cancer.

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.