The Effect of Metformin Use during Docetaxel Chemotherapy on Prostate Cancer Specific and Overall Survival of Diabetic Patients with Castration Resistant Prostate Cancer

Discovery of novel itaconimide-based derivatives as potent HDAC inhibitors for the efficient treatment of prostate cancer

Histone deacetylases (HDACs) are a family of enzymes that play important roles in the development and progression of cancers. Inhibition of HDACs has been widely studied as a therapeutic strategy in the development of anticancer drugs. However, developing HDAC inhibitors that are effective for solid tumors remains a great challenge. In this work, we designed and synthesized a series of itaconimide-based derivatives as potent HDAC inhibitors. Among them, compound 17q exhibited potent inhibition of HDAC1/2/3/6, with good antiproliferative activity in vitro and an excellent pharmacokinetic profile. Compound 17q significantly inhibited tumor growth in a DU145 xenograft tumor model and showed no obvious toxicity. Moreover, when 17q was combined with other prostate cancer therapeutics, outstanding synergistic effects were observed and the toxic side effects of DTX were reduced. Overall, based on the data, these inhibitors may offer promising new targeted therapies for prostate cancer.

The development and benefits of metformin in various diseases

Metformin has been used for the treatment of type II diabetes mellitus for decades due to its safety, low cost, and outstanding hypoglycemic effect clinically. The mechanisms underlying these benefits are complex and still not fully understood. Inhibition of mitochondrial respiratory-chain complex I is the most described downstream mechanism of metformin, leading to reduced ATP production and activation of AMP-activated protein kinase (AMPK). Meanwhile, many novel targets of metformin have been gradually discovered. In recent years, multiple pre-clinical and clinical studies are committed to extend the indications of metformin in addition to diabetes. Herein, we summarized the benefits of metformin in four types of diseases, including metabolic associated diseases, cancer, aging and age-related diseases, neurological disorders. We comprehensively discussed the pharmacokinetic properties and the mechanisms of action, treatment strategies, the clinical application, the potential risk of metformin in various diseases. This review provides a brief summary of the benefits and concerns of metformin, aiming to interest scientists to consider and explore the common and specific mechanisms and guiding for the further research. Although there have been countless studies of metformin, longitudinal research in each field is still much warranted.

Targeting lipid metabolism in metastatic prostate cancer

Despite key advances in the treatment of prostate cancer (PCa), a proportion of men have de novo resistance, and all will develop resistance to current therapeutics over time. Aberrant lipid metabolism has long been associated with prostate carcinogenesis and progression, but more recently there has been an explosion of preclinical and clinical data which is informing new clinical trials. This review explores the epidemiological links between obesity and metabolic syndrome and PCa, the evidence for altered circulating lipids in PCa and their potential role as biomarkers, as well as novel therapeutic strategies for targeting lipids in men with PCa, including therapies widely used in cardiovascular disease such as statins, metformin and lifestyle modification, as well as novel targeted agents such as sphingosine kinase inhibitors, DES1 inhibitors and agents targeting FASN and beta oxidation.

Prognostic value of metformin in cancers: An updated meta-analysis based on 80 cohort studies

BACKGROUND

Experiments have shown that metformin can inhibit cancer cell growth, but clinical observations have been inconsistent, so we pooled the currently available data to evaluate the impact of metformin on cancer survival and progression.

METHODS

PubMed, web of science, Embase, and Cochrane databases were searched. Pooled hazard ratios (HRs) were identified using a random-effects model to estimate the strength of the association between metformin and survival and progression in cancer patients.

RESULTS

We incorporated 80 articles published from all databases which satisfied the inclusion criterion. It showed that metformin was associated with better overall survival (hazard ratio [HR] = 0. 81; 95% confidence interval [CI]: [0.77-0.85]) and cancer-specific survival (HR = 0.79; 95% CI: [0.73-0.86]), and metformin was associated with progression-free survival (HR = 0.76; 95% CI: [0.66-0.87]). In patients with diabetes mellitus, the HR of overall survival was 0.79(95% CI: [0.75-0.83]), progression-free survival was 0.72(95% CI: [0.60-0.85]), and the cancer-specific survival was 0.76(95% CI: [0.68-0.86]). It was proposed that metformin can improve the prognosis of cancer patients with diabetes mellitus.

CONCLUSION

Based on cohort studies, metformin therapy has potential survival benefits for patients with malignancy, especially with the greatest benefits seen in breast cancer on overall survival, progression-free survival, and cancer-specific survival. And metformin also showed potential benefits in cancer-specific survival in colorectal and prostate cancer.

Metformin regulates multiple signaling pathways within castration-resistant human prostate cancer cells

Background

The biguanide metformin has been shown to not only reduce circulating glucose levels but also suppress in vitro and in vivo growth of prostate cancer. However, the mechanisms underlying the anti-tumor effects of metformin in advanced prostate cancers are not fully understood. The goal of the present study was to define the signaling pathways regulated by metformin in androgen-receptor (AR) positive, castration-resistant prostate cancers.

Methods

Our group used RNA sequencing (RNA-seq) to examine genes regulated by metformin within the C4–2 human prostate cancer cell line. Western blot analysis and quantitative RT-PCR were used to confirm alterations in gene expression and further explore regulation of protein expression by metformin.

Results

Data from the RNA-seq analysis revealed that metformin alters the expression of genes products involved in metabolic pathways, the spliceosome, RNA transport, and protein processing within the endoplasmic reticulum. Gene products involved in ErbB, insulin, mTOR, TGF-β, MAPK, and Wnt signaling pathways are also regulated by metformin. A subset of metformin-regulated gene products were genes known to be direct transcriptional targets of p53 or AR. Western blot analyses and quantitative RT-PCR indicated these alterations in gene expression are due in part to metformin-induced reductions in AR mRNA and protein levels.

Conclusions

Together, our results suggest metformin regulates multiple pathways linked to tumor growth and progression within advanced prostate cancer cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10115-3.

Association between baseline body mass index and survival in men with metastatic hormone-sensitive prostate cancer: ECOG-ACRIN CHAARTED E3805

BACKGROUND

E3805 (CHAARTED) is a phase 3 trial demonstrating improved survival for men with metastatic hormone-sensitive prostate cancer (mHSPC) randomized to treatment with docetaxel (D) and androgen-deprivation therapy (ADT) versus ADT alone. We assessed the association of baseline body mass index (BMI) and metformin exposure with quality of life (QOL) and prostate cancer outcomes including survival in patients enrolled in the CHAARTED study.

METHODS

We performed a posthoc exploratory analysis of the CHAARTED trial of men with mHSPC randomized to treatment with ADT with or without D between 2006 and 2012. Cox proportional hazards models and Kruskal-Wallis test were used to evaluate the association between BMI with QOL and prostate cancer outcomes and between metformin exposure and survival.

RESULTS

In 788 of 790 enrolled patients with prospectively recorded baseline BMI and metformin exposure status, lower BMI was not associated with survival, but was associated with high volume disease (p < 0.0001) and poorer baseline QOL on functional assessment of cancer therapy-prostate (p = 0.008). Only 68 patients had prevalent metformin exposure at baseline in the CHAARTED trial. Four groups were identified: ADT + D + metformin (n = 39); ADT + D (n = 357); ADT + metformin (n = 29); and ADT alone (n = 363). Baseline clinicopathologic characteristics were similar between groups. In this small exploratory multivariable analysis, metformin exposure was not associated with survival (hazard ratio: 1.15; 95% confidence interval: 0.81-1.63, p = 0.44).

CONCLUSIONS

There was no link between baseline BMI and survival, but lower baseline BMI was associated with features of greater cancer burden and poorer QOL.

TAXOMET: A French Prospective Multicentric Randomized Phase II Study of Docetaxel Plus Metformin Versus Docetaxel Plus Placebo in Metastatic Castration-Resistant Prostate Cancer

BACKGROUND

Docetaxel (DOCE) is a standard of care in metastatic castration-resistant prostate cancer (mCRPC). Several retrospective studies suggested a decrease in Prostate Cancer incidence and mortality with metformin (MET). MET has also demonstrated anti-tumor activity in Prostate Cancer preclinical models, with increased apoptosis when added to DOCE. We aimed at exploring the role of MET in combination with DOCE in mCRPC.

PATIENTS AND METHODS

Non-diabetic mCRPC patients were randomly assigned to receive DOCE 75 mg/m² every 21 days + prednisone (5 mg. BID) with either MET 850 mg BID (D+M) or placebo (D+P) up to 10 cycles. Prostate-Specific Antigen (PSA) response ≥50% from baseline was the primary end point. Secondary end points included objective response rate (ORR), progression-free survival (PFS), overall survival (OS), toxicity and quality of life (QoL).

RESULTS

Out of 99 patients were randomized (D+M = 50; D+P = 49) in 10 French centers. The median follow-up was 86 (IQR 73-88) months. The PSA-response rate reached 66% in the D+M arm, but was not different from that observed in the D+P arm (63%, P = 0,94). In the D+M and D+P arms, the ORR was 28% and 24%, the median PFS was 7.8 and 6.0 months and the median OS was 27 and 20 months (ns), respectively. Diarrhea grade I to II was more frequent in the MET arm (66% vs. 43%). No impairment of QoL was observed.

CONCLUSION

MET addition failed to improve the standard DOCE regimen in mCRPC. Further research targeting tumor cell metabolism should be performed.

Metformin mitigates PLCε gene expression and modulates the Notch1/Hes and androgen receptor signaling pathways in castration-resistant prostate cancer xenograft models

The present study aimed to establish a mouse model of patient-derived castration-resistant prostate cancer (CRPC) xenograft tumors, and to evaluate the effects of various doses of metformin on phospholipase Cε (PLCε) expression and the neurogenic locus notch homolog protein 1 (Notch1)/hairy and enhancer of split 1 and androgen receptor (AR) signaling pathways via western blotting and reverse transcription-quantitative PCR. Additionally, phorbol 12-myristate 13-acetate was used to activate PLC, and Jagged1 was used as a Notch activator to verify whether metformin could suppress CRPC development via the PLCε/Notch1/AR pathways. The results confirmed that metformin may serve critical roles in CRPC by significantly inhibiting the occurrence, growth and proliferation of CRPC tumors by decreasing PLCε/Notch1 expression and AR nucleation.

Repurposing metformin as anticancer drug: Randomized controlled trial in advanced prostate cancer (MANSMED)

BACKGROUND

The proposal of metformin as an anticancer drug has been explored in many types of cancers. Metformin may act synergistically with standard prostate cancer therapies. However, there is still a debate about the effect of metformin on hormone sensitive prostate cancer (HSPC).

PATIENTS AND METHODS

randomized controlled trial. Eligible patients were high risk locally advanced or metastatic HSPC. Patients were randomly assigned to receive either metformin plus standard of care or standard of care alone. The primary endpoint was castration-resistant prostate cancer-free survival (CRPC-FS). The secondary endpoints were overall survival, PSA level and adverse events.

RESULTS

A total number of 124 patients underwent randomization where 62 patients were allocated in each arm. Over a median follow up of 22 months, the CRPC-FS was significantly improved with metformin (29 months, 95% CI 25-33 vs. 20 months 95% CI 16-24; P = 0.01). After subgroup analysis, the addition of metformin improved the CRPC-FS in patients with high risk localized disease (median not reached vs. 25 months, 95% CI 18-31; P = 0.02) and in patients with metastatic low tumor volume disease (median not reached vs. 15 months, 95% CI 5-25; P = 0.009). No significant difference in overall survival or PSA response in both treatment arms (P = 0.1 and 0.5, respectively). Metformin was not associated with significant adverse events apart from grade II diarrhea.

CONCLUSION

Metformin is a safe and low-cost drug. Combining with androgen deprivation therapy improves the outcome in locally advanced or metastatic prostate cancer. Patients with low volume metastatic prostate cancer seem to drive more benefit.

Metformin alters therapeutic effects in the BALB/c tumor therapy model

BACKGROUND

Despite considerable medical proceedings, cancer is still a leading cause of death. Major problems for tumor therapy are chemoresistance as well as toxic side effects. In recent years, the additional treatment with the antidiabetic drug metformin during chemotherapy showed promising results in some cases. The aim of this study was to develop an in vitro tumor therapy model in order to further investigate the potential of a combined chemotherapy with metformin.

METHODS

Cytotoxic effects of a combined treatment on BALB/c fibroblasts were proven by the resazurin assay. Based on the BALB/c cell transformation assay, the BALB/c tumor therapy model was established successfully with four different and widely used chemotherapeutics from different categories. Namely, Doxorubicin as a type-II isomerase inhibitor, Docetaxel as a spindle toxin, Mitomycin C as an alkylating agent and 5-Fluorouracil as an antimetabolite. Moreover, glucose consumption in the medium supernatant was measured and protein expressions were determined by Western Blotting.

RESULTS

Initial tests for the combined treatment with metformin indicated unexpected results as metformin could partly mitigate the cytotoxic effects of the chemotherapeutic agents. These results were further confirmed as metformin induced resistance to some of the drugs when applied simultaneously in the tumor therapy model. Mechanistically, an increased glucose consumption was observed in non-transformed cells as well as in the mixed population of malignant transformed cell foci and non-transformed monolayer cells, suggesting that metformin could also increase glucose consumption in transformed cells.

CONCLUSION

In conclusion, this study suggests a cautious use of metformin during chemotherapy. Moreover, the BALB/c tumor therapy model offers a potent tool for further mechanistic studies of drug-drug interactions during cancer therapy.

Metformin Use and the Outcome of Metastatic Renal Cell Carcinoma Treated with Sunitinib or Pazopanib

Background

The anticancer properties of metformin have been suggested in numerous experimental studies and several retrospective clinical studies show that its use is associated with improved outcome of patients with cancer. However, limited data are available for patients with metastatic renal cell carcinoma (mRCC) treated with targeted therapy. The aim of this retrospective study was to assess the impact of the metformin use on survival of mRCC patients treated with sunitinib or pazopanib.

Methods

Clinical data from 343 patients with mRCC treated with sunitinib or pazopanib in the first line were analyzed. Progression-free survival (PFS) and overall survival (OS) were compared according to the use of metformin.

Results

The median PFS and OS for patients using metformin was 31.1 (95% CI 20.6–35.1) and 51.6 (95% CI 44.7-NR) months compared to 9.3 (95% CI 8.0–12.0) and 22.4 (95% CI 19.4–26.8) months for patients not using metformin (p<0.0001 and p=0.0002, respectively). Cox multivariate analysis shows that the use of metformin remains a significant factor for PFS (HR=0.55 [95% CI 0.343–0.883], p=0.013) and also for OS (HR=0.45 [95% CI 0.256–0.794], p=0.006).

Conclusion

The present study results suggest that the use of metformin was associated with favorable outcome of mRCC patients treated with sunitinib or pazopanib.

The Chemosensitizing Role of Metformin in Anti-Cancer Therapy

Chemoresistance, which leads to the failure of chemotherapy and further tumor recurrence, presents the largest hurdle for the success of anti-cancer therapy. In recent years, metformin, a widely used first-line antidiabetic drug, has attracted increasing attention for its anti-cancer effects. A growing body of evidence indicates that metformin can sensitize tumor responses to different chemotherapeutic drugs, such as hormone modulating drugs, anti-metabolite drugs, antibiotics, and DNA-damaging drugs via selective targeting of Cancer Stem Cells (CSCs), improving the hypoxic microenvironment, and by suppressing tumor metastasis and inflammation. In addition, metformin may regulate metabolic programming, induce apoptosis, reverse Epithelial to Mesenchymal Transition (EMT), and Multidrug Resistance (MDR). In this review, we summarize the chemosensitization effects of metformin and focus primarily on its molecular mechanisms in enhancing the sensitivity of multiple chemotherapeutic drugs, through targeting of mTOR, ERK/P70S6K, NF-κB/HIF-1 α, and Mitogen- Activated Protein Kinase (MAPK) signaling pathways, as well as by down-regulating the expression of CSC genes and Pyruvate Kinase isoenzyme M2 (PKM2). Through a comprehensive understanding of the molecular mechanisms of chemosensitization provided in this review, the rationale for the use of metformin in clinical combination medications can be more systematically and thoroughly explored for wider adoption against numerous cancer types.>.

Identification and Design of a Next-Generation Multi Epitopes Bases Peptide Vaccine Candidate Against Prostate Cancer: An In Silico Approach

Prostate cancer (PCa) is the second most diagnosed cancer in men and ranked fifth in overall cancer diagnosis. During the past decades, it has arisen as a significant life-threatening disease in men at an older age. At the early onset of illness when it is in localized form, radiation and surgical treatments are applied against this disease. In case of adverse situations androgen deprivation therapy, chemotherapy, hormonal therapy, etc. are widely used as a therapeutic element. However, studies found the occurrences of several side effects after applying these therapies. In current work, several immunoinformatic techniques were applied to formulate a multi-epitopic vaccine from the overexpressed antigenic proteins of PCa. A total of 13 epitopes were identified from the five prostatic antigenic proteins (PSA, PSMA, PSCA, STEAP, and PAP), after validation with several in silico tools. These epitopes were fused to form a vaccine element by (GGGGS)3 peptide linker. Afterward, 5, 6-dimethylxanthenone-4-acetic acid (DMXAA) was used as an adjuvant to initiate and induce STING-mediated cytotoxic cascade. In addition, molecular docking was performed between the vaccine element and HLA class I antigen with the low ACE value of -251 kcal/mol which showed a significant binding. Molecular simulation using normal mode analysis (NMA) illustrated the docking complex as a stable one. Therefore, this observation strongly indicated that our multi epitopes bases peptide vaccine molecule will be an effective candidate for the treatment of the PCa.

Current Status and Application of Metformin for Prostate Cancer: A Comprehensive Review

Metformin, an oral biguanide used for first-line treatment of type 2 diabetes mellitus, has attracted attention for its anti-proliferative and anti-cancer effects in several solid tumors, including prostate cancer (PCa). Liver kinase B1 (LKB1) and adenosine monophosphate-activated protein kinase (AMPK) activation, inhibition of the mammalian target of rapamycin (mTOR) activity and protein synthesis, induction of apoptosis and autophagy by p53 and p21, and decreased blood insulin level have been suggested as direct anti-cancer mechanisms of metformin. Research has shown that PCa development and progression are associated with metabolic syndrome and its components. Therefore, reduction in the risk of PCa and improvement in survival in metformin users may be the results of the direct anti-cancer mechanisms of the drug or the secondary effects from improvement of metabolic syndrome. In contrast, some research has suggested that there is no association between metformin use and PCa incidence or survival. In this comprehensive review, we summarize updated evidence on the relationship between metformin use and oncological effects in patients with PCa. We also highlight ongoing clinical trials evaluating metformin as an adjuvant therapy in novel drug combinations in various disease settings.

Efficacy of Metformin and Chemotherapeutic Agents on the Inhibition of Colony Formation and Shh/Gli1 Pathway: Metformin/Docetaxel Versus Metformin/5-Fluorouracil

BACKGROUND

Gastric cancer is a common gastrointestinal cancer characterized by poor prognosis and chemoresistance. Docetaxel and 5-fluorouracil (5-FU) are frequently used for the treatment of gastric cancer. Despite their potent anti-cancer effects, chemoresistance occurs in metastatic gastric cancer. Metformin, a popular anti-diabetic drug, has been proven to have potent anticancer effects on gastrointestinal cancers. Here, we aim to improve this chemotherapy agents' efficacy by pretreatment with metformin.

METHODS

The AGS gastric cancer cell line were pretreated with three different sub-toxic concentration of metformin and then treated with various concentrations of 5-FU and docetaxel.The anticancer effects of the combination of metformin with the chemotherapy agents were determined using clonogenic assay and DAPi staining. We used real-time PCR to evaluate Gli1, Gli2, and TWIST1 mRNA expression levels in the gastric cancer cells. Also, the expression of the Shh protein was assessed using immunocytochemistry.

RESULTS

Here, we found that metformin sensitized the gastric cancer cells to chemotherapy. The combination treatments were more effective in reducing the number of cancer colonies compared to 5-FU or docetaxel alone. The combination of metformin with 5-FU or docetaxel significantly reduced the number of cells expressing the Shh protein compared to the 5-FU alone or docetaxel alone. Interestingly, we found that the combination of metformin with docetaxel significantly down-regulated the mRNA levels of Gli1, Gli2, and TWIST1 in the AGS gastric cancer cell line compared to docetaxel alone.

CONCLUSION

Overall, our data strongly support an important role for metformin as an enhancer of the efficacy of chemotherapeutic agents against gastric cancer.

Preexisting diabetes, metformin use and long-term survival in patients with prostate cancer

OBJECTIVE

To assess prostate cancer-specific and overall survival in prostate cancer patients with or without preexisting type 2 diabetes mellitus (T2DM) with regards to metformin use.

METHODS

Patients diagnosed with prostate cancer in the Lithuanian population between 2001 and 2005 were identified through the Lithuanian Cancer Registry and followed until 2016, date of death, loss to follow-up or whichever came first. Information regarding the diagnosis of T2DM and antihyperglycemic medications were obtained from the National Health Insurance Fund database. Prostate cancer-specific and overall survival outcomes were analysed using univariate and multivariate Cox proportional hazard models.

RESULTS

Out of 6689 men included, 254 (3.8%) had preexisting T2DM. There were 4807 deaths during follow-up, including 2084 from prostate cancer. No differences were found in prostate cancer-specific survival between men with or without T2DM. The risk of overall mortality was higher (HR = 1.24, 95% CI = 1.07-1.43) in diabetic men. Univariate analysis showed cancer stage at diagnosis and age to be significant predictors of survival. After adjustment for age and stage at diagnosis, there was no difference in prostate-specific survival between non-diabetic patients compared to metformin users or metformin non-users. However, overall survival was lower in T2DM patients, with a higher mortality risk for metformin non-users (HR = 1.63, 95% CI = 1.27-2.10). Prostate cancer-specific mortality risk was insignificantly lower in diabetic men on metformin (HR = 0.74, 95% CI = 0.54-1.02).

CONCLUSION

There was no difference in long-term prostate cancer-specific survival in patients with or without T2DM. Overall survival was lower in T2DM patients not treated with metformin.

NF-κB signaling promotes castration-resistant prostate cancer initiation and progression

Prostate Cancer (PCa) is the second leading cause of cancer-related death in men. Adenocarcinoma of the prostate is primarily composed of Androgen Receptor-positive (AR⁺) luminal cells that require AR transcriptional activity for survival and proliferation. As a consequence, androgen deprivation and anti-androgens are used to treat PCa patients whose disease progresses following attempted surgical or radiation interventions. Unfortunately, patients with advanced PCa can develop incurable castration-resistant PCa (CRPCa) due to mutated, variant, or overexpressed AR. Conversely, low or no AR accumulation or activity can also underlie castration resistance. Whether CRPCa is due to aberrant AR activity or AR independence, NF-κB signaling is also implicated in the initiation and maintenance of CRPCa and, thus, the NF-κB pathway may be a promising alternative therapeutic target. In this review, we present evidence that NF-κB signaling promotes CRPCa initiation and progression, describe the dichotomic role of NF-κB in the regulation of AR expression and activity and outline studies that explore NF-κB inhibitors as PCa therapies.

For colorectal cancer patients with type II diabetes, could metformin improve the survival rate? A meta-analysis

OBJECTIVE

Current research is controversial about whether metformin can improve the survival rate of patients with colon cancer. Therefore, we conducted a meta-analysis to identify the association between metformin and the survival rate of colorectal cancer (CRC) patients with type II diabetes.

METHODS

We conducted a search in databases including Pubmed, EMBASE and Cochrane Library. All articles were published in the last decade, and the quality of each study was evaluated by the Newcastle-Ottawa Scale. Odds ratios (ORs) and its corresponding 95% confidence intervals (CIs) for each study were calculated and summary relative risk estimates with corresponding 95% CIs were generated using the random-effects model. Heterogeneity and publication bias were assessed.

RESULTS

Ten articles were included in this meta-analysis. The included articles were all cohort studies. In a pooled analysis of all studies, metformin using was associated with increased overall survival (OS) rate (OR, 0.54; 95% CI, 0.47 to 0.63) and cancer-specific survival (CS) rate (OR 0.59; 95% CI 0.43 to 0.82) of CRC patients with diabetes. We found that the effect of metformin is associated with geographical region through subgroup meta-analysis.

CONCLUSIONS

Metformin using was associated with an increased OS rate and CS rate of colorectal cancer.

Combination of the natural product capsaicin and docetaxel synergistically kills human prostate cancer cells through the metabolic regulator AMP-activated kinase

Background

Current chemotherapy for castration-resistant prostate cancer is established on taxane-based compounds like docetaxel. However, eventually, the development of toxic side effects and resistance limits the therapeutic benefit being the major concern in the treatment of prostate cancer. Combination therapies in many cases, enhance drug efficacy and delay the appearance of undesired effects, representing an important option for the treatment of castration-resistant prostate cancer. In this study, we tested the efficacy of the combination of docetaxel and capsaicin, the pungent ingredient of hot chili peppers, on prostate cancer cells proliferation.

Methods

Prostate cancer LNCaP and PC3 cell lines were used in this study. Levels of total and phosphorylated forms of Akt, mTOR, S6, LKB1, AMPK and ACC were determined by Western blot. AMPK, LKB1 and Akt knock down was performed by siRNA. PTEN was overexpressed by transient transfection with plasmids. Xenograft prostate tumors were induced in nude mice and treatments (docetaxel and capsaicin) were administered intraperitoneally. Statistical analyses were performed with GraphPad software. Combination index was calculated with Compusyn software.

Results

Docetaxel and capsaicin synergistically inhibited the growth of LNCaP and PC3 cells, with a combination index lower than 1 for most of the combinations tested. Co-treatment with docetaxel and capsaicin notably decreased Akt and its downstream targets mTOR and S6 phosphorylation. Overexpression of PTEN phosphatase abrogated the synergistic antiproliferative effect of docetaxel and capsaicin. The combined treatment also increased the phosphorylation of AMP-activated kinase (AMPK) and the phosphorylation of its substrate ACC. In addition, pharmacological inhibition of AMPK with dorsomorphin (compound C) as well as knock down by siRNA of AMPK or its upstream kinase LKB1, abolished the synergy of docetaxel and capsaicin. Mechanistically, we showed that the synergistic anti-proliferative effect may be attributed to two independent effects: Inhibition of the PI3K/Akt/mTOR signaling pathway by one side, and AMPK activation by the other. In vivo experiments confirmed the synergistic effects of docetaxel and capsaicin in reducing the tumor growth of PC3 cells.

Conclusion

Combination of docetaxel and capsaicin represents a therapeutically relevant approach for the treatment of Prostate Cancer.

Metabolic Alterations, Aggressive Hormone-Naïve Prostate Cancer and Cardiovascular Disease: A Complex Relationship

Background: Epidemiological studies suggest a possible relationship between metabolic alterations, cardiovascular disease and aggressive prostate cancer, however, no clear consensus has been reached. Objective: The aim of the study was to analyze the recent literature and summarize our experience on the association between metabolic disorders, aggressive hormone-naïve prostate cancer and cardiovascular disease. Method: We identified relevant papers by searching in electronic databases such as Scopus, Life Science Journals, and Index Medicus/Medline. Moreover, we showed our experience on the reciprocal relationship between metabolic alterations and aggressive prostate cancer, without the influence of hormone therapy, as well the role of coronary and carotid vasculopathy in advanced prostate carcinoma. Results: Prostate cancer cells have an altered metabolic homeostatic control linked to an increased aggressivity and cancer mortality. The absence of discrimination of risk factors as obesity, systemic arterial hypertension, diabetes mellitus, dyslipidemia and inaccurate selection of vascular diseases as coronary and carotid damage at initial diagnosis of prostate cancer could explain the opposite results in the literature. Systemic inflammation and oxidative stress associated with metabolic alterations and cardiovascular disease can also contribute to prostate cancer progression and increased tumor aggressivity. Conclusions: Metabolic alterations and cardiovascular disease influence aggressive and metastatic prostate cancer. Therefore, a careful evaluation of obesity, diabetes mellitus, dyslipidemia, systemic arterial hypertension, together with a careful evaluation of cardiovascular status, in particular coronary and carotid vascular disease, should be carried out after an initial diagnosis of prostatic carcinoma.

The effect of metformin therapy on incidence and prognosis in prostate cancer: A systematic review and meta-analysis

The relationship between metformin and prostate cancer (PCa) remains controversial. To clarify this association, the PubMed, Embase and Cochrane library databases were systematically searched from their inception dates to May 23, 2018, using the keywords "metformin" and "prostate cancer" to identify the related studies. The results included incidence, overall survival (OS), PCa-specific survival (CSS) and recurrence-free survival (RFS), which were measured as hazard ratios (HR) with a 95% confidence interval (95% CI) using Review Manager 5.3 software. A total of 30 cohort studies, including 1,660,795 patients were included in this study. Our study revealed that metformin treatment improves OS, CSS and RFS in PCa (HR = 0.72, 95% CI: 0.59-0.88, P = 0.001; HR = 0.78, 95% CI: 0.64-0.94, P = 0.009; and HR = 0.60, 95% CI: 0.42-0.87 P = 0.006, respectively) compared with non-metformin treatment. However, metformin usage did not reduce the incidence of PCa (HR = 0.86, 95% CI: 0.55-1.34, P = 0.51). In conclusion, compared with non-metformin treatment, metformin therapy can significantly improve OS, CSS and RFS in PCa patients. No association was noted between metformin therapy and PCa incidence. This study indicates a useful direction for the clinical treatment of PCa.

Statin and metformin therapy in prostate cancer patients with hyperlipidemia who underwent radiotherapy: a population-based cohort study

Purpose

To evaluate the association between the use of statins and/or metformin and patient survival in prostate cancer patients in Taiwan.

Subjects and methods

Newly diagnosed prostate cancer patients who had hyperlipidemia and received radiotherapy were identified from the National Health Insurance Research Database 2000–2010. The survival rate was estimated by the Kaplan–Meier method. Univariate and multivariate Cox regression analyses were performed to examine the association of mortality. Sensitivity analysis was performed to assess the risk of mortality in patients with diabetes.

Results

The study included 567 patients. Patients who used statins or metformin after prostate cancer diagnosis had longer average survival times (9.3 years and 8.1 years, respectively; P=0.001) compared with patients who persistently used or used the medicines prior to cancer diagnosis. Multivariate Cox regression analysis found that patients treated with statins after cancer diagnosis were significantly associated with a lower risk of mortality (aHR =0.24, 95% CI =0.09–0.66) compared to patients who did not use statins during the study period. Patients treated with metformin after cancer diagnosis were significantly associated more with an increased risk of mortality (aHR =6.78, 95% CI =2.45–18.77) compared to patients who did not use metformin during the study period. Sensitivity analysis revealed that the average survival time was similar among different medicine use groups in patients with diabetes.

Conclusion

The finding suggests that statins and metformin use after prostate cancer diagnosis may increase survival in patients with hyperlipidemia and radiotherapy.

Repurposing old drugs in oncology: Opportunities with clinical and regulatory challenges ahead

WHAT IS KNOWN AND OBJECTIVE

In order to expedite the availability of drugs to treat cancers in a cost-effective manner, repurposing of old drugs for oncological indications is gathering momentum. Revolutionary advances in pharmacology and genomics have demonstrated many old drugs to have activity at novel antioncogenic pharmacological targets. We decided to investigate whether prospective studies support the promises of nonclinical and retrospective clinical studies on repurposing three old drugs, namely metformin, valproate and astemizole.

METHODS

We conducted an extensive literature search through PubMed to gather representative nonclinical and retrospective clinical studies that investigated the potential repurposing of these three drugs for oncological indications. We then searched for prospective studies aimed at confirming the promises of retrospective data.

RESULTS AND DISCUSSION

While evidence from nonclinical and retrospective clinical studies with these drugs appears highly promising, large scale prospective studies are either lacking or have failed to substantiate this promise. We provide a brief discussion of some of the challenges in repurposing. Principal challenges and obstacles relate to heterogeneity of cancers studied without considering their molecular signatures, trials with small sample size and short duration, failure consider issues of ethnicity of study population and effective antioncogenic doses of the drug studied.

WHAT IS NEW AND CONCLUSION

Well-designed prospective studies demonstrating efficacy are required for repurposing old drugs for oncology indications, just as they are for new chemical entities for any indication. Early and ongoing interactions with regulatory authorities are invaluable. We outline a tentative framework for a structured approach to repurposing old drugs for novel indications in oncology.

Phenformin alone or combined with gefitinib inhibits bladder cancer via AMPK and EGFR pathways

Background

In previous studies, we have shown that the combination of metformin and gefitinib inhibits the growth of bladder cancer cells. Here we examined whether the metformin analogue phenformin, either used alone or in combination with gefitinib, could inhibit growth of bladder cancer cells.

Methods

The growth-inhibitory effects of phenformin and gefitinib were tested in one murine and two human bladder cancer cell lines using MTT and clonogenic assays. Effects on cell migration were assessed in a wound healing assay. Synergistic action between the two drugs was assessed using CompuSyn software. The potential involvement of AMPK and EGFR pathways in the effects of phenformin and gefitinib was explored using Western blotting.

Results

In MTT and clonogenic assays, phenformin was > 10-fold more potent than metformin in inhibiting bladder cancer cell growth. Phenformin also potently inhibited cell migration in wound healing assays, and promoted apoptosis. AMPK signaling was activated; EGFR signaling was inhibited. Phenformin was synergistic with gefitinib, with the combination of drugs showing much stronger anticancer activity and apoptotic activation than phenformin alone.

Conclusions

Phenformin shows potential as an effective drug against bladder cancer, either alone or in combination with gefitinib.

Combination Therapies Using Metformin and/or Valproic Acid in Prostate Cancer: Possible Mechanistic Interactions

Prostate cancer (PCa) is the most frequent cancer in men. The evolution from local PCa to castration-resistant PCa, an end-stage of disease, is often associated with changes in genes such as p53, androgen receptor, PTEN, and ETS gene fusion products. Evidence is accumulating that repurposing of metformin (MET) and valproic acid (VPA) either when used alone, or in combination, with another therapy, could potentially play a role in slowing down PCa progression. This review provides an overview of the application of MET and VPA, both alone and in combination with other drugs for PCa treatment, correlates the responses to these drugs with common molecular changes in PCa, and then describes the potential for combined MET and VPA as a systemic therapy for prostate cancer, based on potential interacting mechanisms.

The impact of metformin use on survival in prostate cancer: a systematic review and meta-analysis

Background

Metformin has been implicated to reduce the risk of prostate cancer (PCa) beyond its glucose-lowering effect. However, the influence of metformin on prognosis of PCa is often controversial.

Results

A total of 13 cohort studies encompassing 177,490 individuals were included in the meta-analysis. Data on overall survival (OS) and cancer-specific survival (CSS) was extracted from 8 and six studies, respectively. Comparing metformin users with non-metformin users, the pooled hazard ratios (HRs) for OS and CSS were 0.79 (95% confidence interval [CI] 0.63-0.98) and 0.76 (95% CI 0.57-1.02), respectively. Subgroup analyses stratified by baseline charcteristics indicated significant CSS benefits were noted in studies conducted in USA/Canada with prospective, large sample size, multiple-centered study design. Five studies reported the PCa prognosis for recurrence-free survival (RFS) and metformin use was significantly associated with patient RFS (HR 0.74, 95% CI, 0.58-0.95).

Methods

Relevant studies were searched and identified using PubMed, Embase and Cochrane databases from inception through January 2017, which investigated associations between the use of metformin and PCa prognosis. Combined HRs with 95% CI were pooled using a random-effects model. The primary outcomes of interest were OS and CSS.

Conclusions

Our findings provide indication that metformin therapy has a trend to improve survival for patients with PCa. Further prospective, multi-centered, large sample size cohort studies are warranted to determine the true relationship.

Metformin use and survival outcomes in endometrial cancer: a systematic review and meta-analysis

Previous studies have evaluated the effects of metformin use on survival outcomes in endometrial cancer, but their results are inconsistent. We conducted a systematic review and meta-analysis to provide a quantitative assessment of the drug's effects based on available evidence. We searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials to identify relevant studies that evaluated the association between metformin use on survival outcomes in endometrial cancer. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated to evaluate the association of metformin use with overall survival and with progression-free survival using a fixed-effects model. A total of nine studies involving 2,016 patients with endometrial cancer were identified. In a meta-analysis of eight studies involving 1,594 individuals, metformin use was associated with significant improvements in overall survival (HR, 0.51; 95% CI, 0.41 to 0.64). Metformin users similarly showed improved progression-free survival in a meta-analysis of two studies involving 632 individuals (HR, 0.63; 95% CI, 0.46 to 0.87). In conclusion, endometrial cancer patients who use metformin show improved overall survival and progression-free survival. Further studies are required to confirm the full potential effects of metformin use on survival outcomes in endometrial cancer.

Chloride intracellular channel 1 regulates the antineoplastic effects of metformin in gallbladder cancer cells

Metformin is the most commonly used drug for type 2 diabetes and has potential benefit in treating and preventing cancer. Previous studies indicated that membrane proteins can affect the antineoplastic effects of metformin and may be crucial in the field of cancer research. However, the antineoplastic effects of metformin and its mechanism in gallbladder cancer (GBC) remain largely unknown. In this study, the effects of metformin on GBC cell proliferation and viability were evaluated using the Cell Counting Kit‐8 (CCK‐8) assay and an apoptosis assay. Western blotting was performed to investigate related signaling pathways. Of note, inhibition, knockdown and upregulation of the membrane protein Chloride intracellular channel 1 (CLIC1) can affect GBC resistance in the presence of metformin. Our data demonstrated that metformin apparently inhibits the proliferation and viability of GBC cells. Metformin promoted cell apoptosis and increased the number of early apoptotic cells. We found that metformin can exert growth‐suppressive effects on these cell lines via inhibition of p‐Akt activity and the Bcl‐2 family. Notably, either dysfunction or downregulation of CLIC1 can partially decrease the antineoplastic effects of metformin while upregulation of CLIC1 can increase drug sensitivity. Our findings provide experimental evidence for using metformin as an antitumor treatment for gallbladder carcinoma.

The impact of metformin use on survival in kidney cancer patients with diabetes: a meta-analysis

PURPOSE

The effects of metformin on the prognosis of kidney cancer patients with diabetes are in controversial. The present study is conducted to classify the association of metformin use with the survival of patients with kidney cancer.

METHODS

Electronic databases, namely PubMed and Web of Science, were used to search the eligible studies up to December, 2016. Pooled hazard ratio (HR) and its corresponding 95% confidence interval (95% CI) were calculated. It was considered as statistically significant when P value was <0.05.

RESULTS

Eight cohorts were eligible for the present meta-analysis, including 254,329 kidney cancer patients. The combined HR suggested that the use of metformin could improve the overall survival (OS) (HR 0.643, 95% CI 0.520-0.795, P < 0.001) and cancer-specific survival (CSS) (HR 0.618, 95% CI 0.446-0.858, P = 0.004) in kidney cancer patients. In subgroup analysis, positive associations were found between metformin use and OS/CSS of localized renal cell carcinoma patients (OS: HR 0.634, 95% CI 0.440-0.913, P = 0.014; CSS: HR 0.476, 95% CI 0.295-0.768, P = 0.002). Moreover, we also found that the use of metformin could reduce the risk of death in kidney cancer patients (HR 0.711, 95% CI 0.562-0.899, P = 0.004).

CONCLUSION

Our findings suggest that the use of metformin is in favor of the prognosis of patients with kidney cancers. Further investigations are needed to evaluate the prognostic value of metformin on kidney cancer patients.