Stem-like cells in bladder cancer cell lines with differential sensitivity to cisplatin.

BACKGROUND: Recurrence is a common problem in bladder cancer; this has been attributed to cancer stem cells. In this study, we characterized potential cancer stem cell populations isolated from three cell lines that demonstrate different responses to cisplatin. MATERIALS AND METHODS: The ALDEFLUOR® assay was used to isolate cells from TCCSUP, T24, and 5637 cell lines, and these cells were evaluated for their ability to form colonies, differentiate, migrate and invade. RESULTS: The cell lines demonstrate a spectrum of aldehyde dehydrogenase high (ALDH(High)) populations that correlate with resistance to cisplatin. In the two resistant cell lines, T24 and 5637, the ALDH(High) cells demonstrate increased colony formation, migration, invasion, and ability to differentiate. The resistant T24 and 5637 cell lines may serve as models to investigate alternative therapies for bladder cancer.

miR-125b promotes growth of prostate cancer xenograft tumor through targeting pro-apoptotic genes.

BACKGROUND: Increasing evidence demonstrates that aberrantly regulated microRNAs (miRNAs) contribute to the initiation and progression of human cancer. We previously have demonstrated that miR-125b stimulated the growth of prostate cancer (CaP) cells. In this study, we further determined the influence of miR-125b on the pathogenesis of CaP. METHODS: To evaluate the effect of miR-125b on xenograft tumor growth, male athymic mice were subcutaneously injected with PC-346C-miR-125b cells that stably overexpressed miR-125b. Potential direct target transcripts of miR-125b were identified using a bioinformatics approach and three miR-125b targeted molecules were confirmed by means of biochemical analyses. RESULTS: Enforced expression of miR-125b promoted tumor growth in both intact and castrated male nude mice. In an effort to define the molecular mechanism(s) mediating its tumor growth properties, we found that miR-125b directly targets eight transcripts, including three key pro-apoptotic genes: p53, Puma, and Bak1. Increasing the abundance of miR-125b resulted in a dramatic decrease in the levels of these three proteins in CaP cells. A direct repressive effect on each of these was supported by the ability of miR-125b to significantly reduce the activity of luciferase reporters containing their 3'-untranslated regions of each gene encompassing the miR-125b-binding sites. Additionally, we found that repression of miR-125b activity was able to sensitize CaP cells to different therapeutic interventions. CONCLUSION: Data obtained in this study demonstrate that miR-125b promotes growth of prostatic xenograft tumors by down-regulating three key pro-apoptotic genes. This suggests that miR-125b is oncogenic and makes it an attractive therapeutic target in CaP.

MicroRNAs and prostate cancer.

Prostate cancer (CaP) is the most frequently diagnosed malignant tumour and the second leading cause of cancer deaths in American men. One of the most troubling aspects of this disease is that, after androgen ablation therapy, androgen-dependent cancer cells inevitably progress to an androgen-independent status, for which no effective treatment has yet been developed. To date, the mechanisms that underlie the occurrence and progression of CaP remain largely unknown. Recent studies suggest that microRNAs (miRNAs) are involved in human tumourigenesis. Some aberrantly expressed miRNAs have been discovered in CaP cell lines, xenografts and clinical tissues and these CaP-related miRNAs may play critical roles in the pathogenesis of CaP. This review provides an overview of current findings about aberrantly expressed miRNAs in CaP. Although a number of CaP-related miRNAs were discovered, to date, only five are characterized for their functionalities: three as oncogenes and two as tumour suppressors. To understand the mechanisms of miRNA action as oncogenes or tumour suppressors, mRNA targets of miRNAs were characterized. Oncogenic miRNAs down-regulate the expression of apoptosis-related genes, and tumour suppressor miRNAs target the proliferation-related genes. Importantly, there is evidence that CaP-related miRNAs are regulated through androgen signalling and that this regulation may contribute to the development of androgen independence. Due to the oncogenic or tumour-suppressive properties of CaP-related miRNAs, they are highly likely to be of clinical use first as biomarkers but more importantly as therapeutic targets for prostate cancer treatment in the near future.

Genistein combined polysaccharide enhances activity of docetaxel, bicalutamide and Src kinase inhibition in androgen-dependent and independent prostate cancer cell lines.

OBJECTIVE: To determine the benefit of genistein combined polysaccharide (GCP) in combination with the androgen receptor antagonist bicalutamide, the antimicrotubule taxane docetaxel, and the Src kinase inhibitor pp2 as part of a treatment regimen for advanced prostate cancer (CaP). MATERIALS AND METHODS: The growth inhibitory and apoptotic effects of GCP in combination with bicalutamide, docetaxel and pp2 were evaluated in both the androgen-dependent LNCaP line, and three androgen-independent lines: CWR22Rv1, PC-3, and LNCaP-R273H. The LNCaP-R273H model is an LNCaP variant expressing a p53(GOF) allele; like CWR22Rv1 and PC-3, it is able to grow in a minimal androgen environment. The effects of GCP treatment in combination with the aforementioned drugs were measured using an MTT assay, Western blotting, flow cytometric analysis, and caspase activation assay. Altered schedules of drug administration were explored using combinations of GCP and docetaxel. RESULTS: GCP potentiated the activity of docetaxel in all four cell lines, resulting in growth inhibition and increased apoptosis. The combination of GCP and bicalutamide had enhanced activity in both the LNCaP and LNCaP-R273H lines, which may better represent patient tumour cells after progression to androgen independence. Administration of docetaxel followed by GCP resulted in a synergistic interaction in LNCaP cells, with increased apoptosis. By contrast, GCP administered first showed subadditivity, probably resulting from GCP-mediated induction of G1 arrest interfering with docetaxel activity. CONCLUSION: These data suggest that GCP, an isoflavone-enriched compound with minimal side-effects and far superior intestinal absorption rate of genistein, has significant clinical potential in combination with docetaxel, bicalutamide or targeted agents for the treatment of advanced CaP.