High Sensitivity of an Ha-RAS Transgenic Model of Superficial Bladder Cancer to Metformin Is Associated with ∼240-Fold Higher Drug Concentration in Urine than Serum

The Potent Anti-Tumor Effects of Rhodiola Drinking Are Associated with the Inhibition of the mTOR Pathway and Modification of Tumor Metabolism in the UPII-Mutant Ha-Ras Model

Background: SHR-5 has been used as an "adaptogen" for enhancing physical and mental performance and for fighting stress in the healthy population. The purpose of this study is to determine the chemopreventive efficacy of SHR-5 for superficial bladder cancer and to investigate the underlying mechanisms of action. Methods: UPII-mutant Ha-ras bladder-cancer-transgenic mice, that developed low-grade and noninvasive papillary transitional urothelial cell carcinoma, were fed with 1.25 and 6.25 mg/mL SHR-5 in drinking water for 6 months. The survival of the mice, obstructive uropathy, tumor burden and morphology, and proliferation were evaluated by pathological, molecular, metabolic, and statistical analyses. Results: Approximately 95% or more of the male UPII-mutant Ha-ras mice that drank SHR-5 daily survived over 6 months of age, while only 33.3% of those mice that drank normal water survived over 6 months of age (p < 0.0001); SHR-5 drinking exposure also reduced tumor-bearing bladder weight and urinary tract obstruction and inhibited mTOR signaling in neoplastic tissues. Global metabolic analysis revealed that SHR-5 resulted in increased phenolic metabolites and decreased CoA, a critical metabolic cofactor for lipid metabolism. Conclusions: Our findings highlight the potential of SHR-5 as an anti-aging agent for bladder cancer prevention through reshaping tumor metabolism via the inhibition of the mTOR signaling. Global metabolomics profiling provides a unique and efficient tool for studying the mechanisms of complex herb extracts' action.

Kawain Inhibits Urinary Bladder Carcinogenesis through Epigenetic Inhibition of LSD1 and Upregulation of H3K4 Methylation

Epidemiological evidence suggests that kava (Piper methysticum Forst) drinks may reduce the risk of cancer in South Pacific Island smokers. However, little is known about the anti-carcinogenic effects of kava on tobacco smoking-related bladder cancer and its underlying mechanisms. Here we show that dietary feeding of kawain (a major active component in kava root extracts) to mice either before or after hydroxy butyl(butyl) nitrosamine (OH-BBN) carcinogen exposure slows down urinary bladder carcinogenesis and prolongs the survival of the OH-BBN-exposed mice. OH-BBN-induced bladder tumors exhibit significantly increased expression of lysine-specific demethylase 1 (LSD1), accompanied by decreased levels of H3K4 mono-methylation compared to normal bladder epithelium, whereas dietary kawain reverses the effects of OH-BBN on H3K4 mono-methylation. Human bladder cancer tumor tissues at different pathological grades also show significantly increased expression of LSD1 and decreased levels of H3K4 mono-methylation compared to normal urothelium. In addition, kava root extracts and the kavalactones kawain and methysticin all increase the levels of H3K4 mono- and di-methylation, leading to inhibitory effects on cell migration. Taken together, our results suggest that modification of histone lysine methylation may represent a new approach to bladder cancer prevention and treatment and that kavalactones may be promising agents for bladder cancer interception in both current and former smokers.

Kavalactone Kawain Impedes Urothelial Tumorigenesis in UPII-Mutant Ha-Ras Mice via Inhibition of mTOR Signaling and Alteration of Cancer Metabolism

UPII-mutant Ha-ras transgenic mice develop urothelial hyperplasia and low-grade papillary carcinoma, which mimics human non-muscle invasive bladder cancer (NMIBC). We investigated the effects and mechanisms of kawain, a main kavalactone in the kava plant, on oncogenic Ha-ras-driven urothelial carcinoma in these mice. The mice were fed at six weeks of age with vehicle control or kawain (6 g/kg) formulated food for approximately five months. Seventy-eight percent of the mice or more fed with kawain food survived more than six months of age, whereas only 32% control food-fed male mice survived, (p = 0.0082). The mean wet bladder weights (a surrogate for tumor burden) of UPII-mutant Ha-ras transgenic mice with kawain diet was decreased by approximately 56% compared to those fed with the control diet (p = 0.035). The kawain diet also significantly reduced the occurrence of hydronephrosis and hematuria in UPII-mutant Ha-ras transgenic mice. Histological examination and immunohistochemistry analysis revealed that vehicle control-treated mice displayed more urothelial carcinoma and Ki67-positive cells in the bladder compared to kawain treated mice. Global metabolic profiling of bladder tumor samples from mice fed with kawain food showed significantly more enrichment of serotonin and less abundance of xylulose, prostaglandin A2, D2 and E2 compared to those from control diet-fed mice, suggesting decreased shunting of glucose to the pentose phosphate pathway (PPP) and reduced inflammation. In addition, kawain selectively inhibited the growth of human bladder cancer cell lines with a significant suppression of 4E-BP1 expression and rpS6 phosphorylation. These observations indicate a potential impact of kawain consumption on bladder cancer prevention by rewiring the metabolic programs of the tumor cells.

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-model 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.

Chemoprevention of Urothelial Cell Carcinoma Tumorigenesis by Dietary Flavokawain A in UPII-Mutant Ha-ras Transgenic Mice

Non-muscle-invasive bladder cancer (NMIBC) has one of the highest recurrence rates among all solid cancers and the highest lifetime treatment cost per patient. Therefore, the development of chemoprevention strategies for reducing the occurrence and recurrence of NMIBC as well as its burdens on the healthcare system is valuable. Our aim was to determine whether flavokawain A (FKA), a kava chalcone isolated from the kava plant, can target the in vivo activated Ha-ras pathway for prevention and treatment of NMIBC. UPII-mutant Ha-ras transgenic mice that develop papillary urothelial cell carcinoma were fed orally with vehicle control or FKA-formulated food for 6 months starting at 6 weeks of age. Seventy-nine percent (15/19) of male mice fed with 6 g FKA per kilogram (kg) of food survived beyond the 6 months of treatment, while 31.6% (6/19) of control food-fed male mice survived the 6-month treatment period (p = 0.02). The mean bladder weights in FKA vs. control food-fed mice were 0.216 ± 0.033 vs. 0.342 ± 0.039 g in male mice (p = 0.0413) and 0.043 ± 0.004 vs. 0.073 ± 0.004 g in female mice (p < 0.0001); FKA reduced bladder weight by 37% and 41%, respectively. The tumor burdens, determined by the wet bladder weight, in these mice were inversely related to plasma FKA concentrations. In addition to decreased bladder weight, FKA treatment significantly reduced the incidences of hydronephrosis and hematuria. FKA-treated mice exhibited more well-differentiated tumors in the bladder and ureter. Immunohistochemical analysis of FKA-treated tumors compared to those in the control group revealed fewer Ki-67- and survivin-positive cells and an increased number of p27- and TUNEL-positive cells, indicating that FKA inhibits proliferation and induces apoptosis. Overall, the results suggest that FKA can target the in vivo activated Ha-ras pathway for the prevention and treatment of NMIBC.

Study protocol of a phase II clinical trial of oral metformin for the intravesical treatment of non-muscle invasive bladder cancer

BACKGROUND

Non-muscle-invasive bladder cancer (NMIBC) is the most common neoplasm of the urinary tract and requires life-long invasive surveillance to detect disease recurrence. Currently, there are no effective oral therapies that delay disease recurrence or progression. We recently demonstrated that in mice, metformin accumulates unchanged in the urine. Urothelial cells are exposed to metformin concentrations ~ 240-fold higher than in serum. This was effective in the treatment of mouse bladder cancer models.

METHODS

We describe the protocol of a multi-centre, open-label, phase II clinical trial of metformin in up to 49 evaluable patients with intermediate-risk NMIBC with the aim to determine the overall response to administration of oral metformin for 3 months on a marker tumour deliberately left following transurethral resection of multiple, papillary NMIBC tumours. All patients will receive metformin orally at doses up to 3000 mg per day. Metformin treatment will start within 2 weeks following transurethral resection of all tumours except one marker lesion. After 3 months of metformin treatment, the effect of metformin on the marker lesion is evaluated by cystoscopy and biopsy under anaesthesia. Residual tumour, if present at this evaluation, will be resected. In case of complete disappearance of the marker lesion, the former tumour area will be biopsied. The primary outcome is the complete response rate of the marker lesion, as determined by decentralised scoring of pre- and post-treatment cystoscopy images by expert independent urologists. Secondary outcomes are the partial response rate, overall safety of metformin and the duration of the time to recurrence.

DISCUSSION

Preclinical studies show the potential role of oral metformin treatment in the management of NMIBC. It could offer an alternative to current adjuvant intravesical treatment. If positive, the reported results of this study could warrant further phase III trials to compare the efficacy of metformin against current treatments of intravesical installations with chemotherapy or Bacillus Calmette-Guérin (BCG).

TRIAL REGISTRATION

This trial is registered in ClinicalTrials.gov under NCT03379909.

Development of a murine intravesical orthotopic human bladder cancer (mio-hBC) model

We have developed a murine intravesical orthotopic human bladder cancer (mio-hBC) model for the establishment of superficial urothelial cell carcinomas. In this model we catheterize female atyhmic nude mice and pre-treat the bladder with poly-L-lysine for 15 minutes, followed by intravesical instillation of luciferase-transfected human UM-UC-3 cells. Cancer cells are quantified by bioluminescent imaging which has been validated by small animal ultrasound. Poly-L-lysine pre-treatment increased engraftment rate (84.4%) and resulted in faster growing tumors than trypsin pre-treatment. In addition, tumors respond through a decrease in growth and increase in apoptosis to chemotherapy with mitomycin C. Previous intravesical models utilized KU7 cells which have been later determined to be of non-bladder origin. They display markers consistent with HeLa cells, requiring a need for a true intravesical bladder model. Efficient engraftment and rapid superficial growth patterning of the human bladder tumor differentiate this in vivo orthotopic model from previous bladder models.

The 150 most important questions in cancer research and clinical oncology series: questions 94-101 : Edited by Cancer Communications

Since the beginning of 2017, Cancer Communications (former title: Chinese Journal of Cancer) has published a series of important questions regarding cancer research and clinical oncology, to provide an enhanced stimulus for cancer research, and to accelerate collaborations between institutions and investigators. In this edition, the following 8 valuable questions are presented. Question 94. The origin of tumors: time for a new paradigm? Question 95. How can we accelerate the identification of biomarkers for the early detection of pancreatic ductal adenocarcinoma? Question 96. Can we improve the treatment outcomes of metastatic pancreatic ductal adenocarcinoma through precision medicine guided by a combination of the genetic and proteomic information of the tumor? Question 97. What are the parameters that determine a competent immune system that gives a complete response to cancers after immune induction? Question 98. Is high local concentration of metformin essential for its anti-cancer activity? Question 99. How can we monitor the emergence of cancer cells anywhere in the body through plasma testing? Question 100. Can phytochemicals be more specific and efficient at targeting P-glycoproteins to overcome multi-drug resistance in cancer cells? Question 101. Is cell migration a selectable trait in the natural evolution of carcinoma?

Rhodiola rosea L.: an herb with anti-stress, anti-aging, and immunostimulating properties for cancer chemoprevention

Purpose of review

Rhodiola rosea extracts have been used as a dietary supplement in healthy populations, including athletes, to non-specifically enhance the natural resistance of the body to both physical and behavior stresses for fighting fatigue and depression. We summarize the information with respect to the new pharmacological activities of Rhodiola rosea extracts and its underlying molecular mechanisms in this review article.

Recent findings

In addition to its multiplex stress-protective activity, Rhodiola rosea extracts have recently demonstrated its anti-aging, anti-inflammation, immunostimulating, DNA repair and anti-cancer effects in different model systems. Molecular mechanisms of Rhodiola rosea extracts's action have been studied mainly along with one of its bioactive compounds, salidroside. Both Rhodiola rosea extracts and salidroside have contrast molecular mechanisms on cancer and normal physiological functions. For cancer, Rhodiola rosea extracts and salidroside inhibit the mTOR pathway and reduce angiogenesis through down-regulation of the expression of HIF-1α/HIF-2α. For normal physiological functions, Rhodiola rosea extracts and salidroside activate the mTOR pathway, stimulate paracrine function and promote neovascularization by inhibiting PHD3 and stabilizing HIF-1α proteins in skeletal muscles. In contrast to many natural compounds, salidroside is water-soluble and highly bioavailable via oral administration and concentrated in urine by kidney excretion.

Summary

Rhodiola rosea extracts and salidroside can impose cellular and systemic benefits similar to the effect of positive lifestyle interventions to normal physiological functions and for anti-cancer. The unique pharmacological properties of Rhodiola rosea extracts or salidroside deserve further investigation for cancer chemoprevention, in particular for human urinary bladder cancer.

Results from 11C-metformin-PET scans, tissue analysis and cellular drug-sensitivity assays questions the view that biguanides affects tumor respiration directly

The anti-diabetic biguanide drugs metformin (METF) and phenformin (PHEN) may have anti-cancer effects. Biguanides suppress plasma growth factors, but nonetheless, the view that these mitochondrial inhibitors accumulate in tumor tissue to an extent that leads to severe energetic stress or alleviation of hypoxia-induced radioresistance is gaining ground. Our cell studies confirm that biguanides inhibits cell proliferation by targeting respiration, but only at highly suprapharmacological concentrations due to low drug retention. Biodistribution/PET studies of ¹¹C-labeled metformin (¹¹C-METF) revealed that plasma bioavailability remained well below concentrations with metabolic/anti-proliferative in vitro effects, following a high oral dose. Intraperitoneal administration resulted in higher drug concentrations, which affected metabolism in normal organs with high METF uptake (e.g., kidneys), but tumor drug retention peaked at low levels comparable to plasma levels and hypoxia was unaffected. Prolonged intraperitoneal treatment reduced tumor growth in two tumor models, however, the response did not reflect in vitro drug sensitivity, and tumor metabolism and hypoxia was unaffected. Our results do not support that direct inhibition of tumor cell respiration is responsible for reduced tumor growth, but future studies using ¹¹C-METF-PET are warranted, preferably in neoplasia’s originating from tissue with high drug transport capacity, to investigate the controversial idea of direct targeting.

Metformin and cancer: Quo vadis et cui bono?

How many lives have already been saved by the anti-cancer drug metformin? Inadvertently perhaps, among the millions of type 2 diabetics with occult or known cancers and who have been prescribed metformin since the 1950s, thousands may have benefited from the anticancer properties of this first-line pharmacotherapy. Quo vadis? Now, researchers aim to move metformin from a non-targeted stage of cancer therapy that has been mostly developed retrospectively and empirically into a targeted therapy by following a biological rationale and a predefined mechanism of action. But, who might benefit from metformin? Cui bono? Because metformin is on the leading edge of a new generation of cancer metabolism-targeted therapies, perhaps it is the right time to provide solutions to the challenges that metformin and other onco-biguanides will face in the coming years before becoming incorporated into the therapeutic armamentarium against cancer.