Overexpression of miR-17-5p may negatively impact p300/CBP factor-associated inflammation in a hypercholesterolemic advanced prostate cancer model.

BACKGROUND: Previously, we demonstrated that cholesterol triggers the increase in p300/CBP-associated factor (PCAF), targeted by miR-17-5p. The p300, IL-6, PCAF, and miR-17-5p genes have important and contradictory roles in inflammation and prostate cancer (PCa). This study aimed to demonstrate the potential anti-inflammatory effect of miR-17-5 in an advanced PCa model with diet-induced hypercholesterolemia. METHODS AND RESULTS: In vitro, using the PC-3 cell line, we show that induction of miR-17-5p reduces p300 and PCAF expression, increases apoptosis, and decreases cell migration. Furthermore, we demonstrate that supplementing this same cell with cholesterol (2 µg/mL) triggers increased p300, IL-6, and PCAF. In vivo, after establishing the hypercholesterolemic (HCOL) model, xenografts were treated with miR-17-5p. Increased expression of this miR after intratumoral injections attenuated tumor growth in the control and HCOL animals and reduced cell proliferation. CONCLUSION: Our results demonstrate that inducing miR-17-5p expression suppresses tumor growth and inflammatory mediator expression. Further studies should be conducted to fully explore the role of miR-17-5p and the involvement of inflammatory mediators p300, PCAF, and IL-6.

Intratumoral Restoration of miR-137 Plus Cholesterol Favors Homeostasis of the miR-137/Coactivator p160/AR Axis and Negatively Modulates Tumor Progression in Advanced Prostate Cancer.

MicroRNAs (miRNAs) have gained a prominent role as biomarkers in prostate cancer (PCa). Our study aimed to evaluate the potential suppressive effect of miR-137 in a model of advanced PCa with and without diet-induced hypercholesterolemia. In vitro, PC-3 cells were treated with 50 pmol of mimic miR-137 for 24 h, and gene and protein expression levels of SRC-1, SRC-2, SRC-3, and AR were evaluated by qPCR and immunofluorescence. We also assessed migration rate, invasion, colony-forming ability, and flow cytometry assays (apoptosis and cell cycle) after 24 h of miRNA treatment. For in vivo experiments, 16 male NOD/SCID mice were used to evaluate the effect of restoring miR-137 expression together with cholesterol. The animals were fed a standard (SD) or hypercholesterolemic (HCOL) diet for 21 days. After this, we xenografted PC-3 LUC-MC6 cells into their subcutaneous tissue. Tumor volume and bioluminescence intensity were measured weekly. After the tumors reached 50 mm3, we started intratumor treatments with a miR-137 mimic, at a dose of 6 µg weekly for four weeks. Ultimately, the animals were killed, and the xenografts were resected and analyzed for gene and protein expression. The animals' serum was collected to evaluate the lipid profile. The in vitro results showed that miR-137 could inhibit the transcription and translation of the p160 family, SRC-1, SRC-2, and SRC-3, and indirectly reduce the expression of AR. After these analyses, it was determined that increased miR-137 inhibits cell migration and invasion and impacts reduced proliferation and increased apoptosis rates. The in vivo results demonstrated that tumor growth was arrested after the intratumoral restoration of miR-137, and proliferation levels were reduced in the SD and HCOL groups. Interestingly, the tumor growth retention response was more significant in the HCOL group. We conclude that miR-137 is a potential therapeutic miRNA that, in association with androgen precursors, can restore and reinstate the AR-mediated axis of transcription and transactivation of androgenic pathway homeostasis. Further studies involving the miR-137/coregulator/AR/cholesterol axis should be conducted to evaluate this miR in a clinical context.

Cholesterol Triggers Nuclear Co-Association of Androgen Receptor, p160 Steroid Coactivators, and p300/CBP-Associated Factor Leading to Androgenic Axis Transactivation in Castration-Resistant Prostate Cancer.

BACKGROUND/AIMS: Cholesterol modulates intratumoral androgenic signaling in prostate cancer; however, the molecular mechanisms underlying these changes in castration-resistant prostate cancer (CRPC) are not fully elucidated. Herein, we investigated the effect of cholesterol on androgen receptor (AR) coactivators expression and tumorigenesis in vitro and in vivo. METHODS: Herein, we monitored the expression of AR coactivators (SRC-1, 2, 3 and PCAF) genes in PC-3 cells exposed to 2µg/mL of cholesterol for 8 hours by qPCR. We also performed cell migration at 0, 8, 24, 48 and 72h and flow cytometry assays (viability, apoptosis, and cell cycle) after a 24h exposure. Immunofluorescence assay was performed to evaluate the protein expression of the AR coactivators. Additionally, in vivo experiments were conducted using 22 male NOD/SCID mice. Mice were fed a standard (Control) or hypercholesterolemic (HCOL) diet for 21 days and then subcutaneously implanted with PC-3 cells. The tumor volume was calculated every two days, and after four weeks, the tumors were resected, weighed, and the serum lipid profile was measured. We also measured the intratumoral lipid profile and AR coactivators gene and protein expression by qPCR and Western Blot, respectively. Intratumor testosterone and dihydrotestosterone (DHT) concentrations were determined using ELISA. RESULTS: Cholesterol up-regulated the gene expression of coactivators SRC-1, SRC-2, SRC-3and PCAF, increasing AR expression in PC-3 cells. Next, cholesterol-supplemented PC-3 cells exhibited increased cell migration and altered cell cycle phases, leading to changes in proliferation and reduced apoptosis. We found that SRC-1, SRC-2, SRC-3 and PCAF proteins co-localized in the nucleus of cholesterol-supplemented cells and co-associate with AR. In the in vivo model, the hypercholesterolemic (HCOL) group displayed higher serum total and intratumoral cholesterol levels, increased testosterone and dihydrotestosterone concentrations, and up-regulated AR coactivator expression. The tumor volume of the HCOL group was significantly higher than the control group. CONCLUSION: Our findings revealed that increased nuclear translocation of the coactivators leads to up-regulated AR gene and protein expression, potentially influencing tumor progression. Studies targeting cholesterol-modulated changes in AR coactivator expression may provide insights into the molecular mechanisms associated with the CRPC phenotype.

Can increased expression of miR-Let-7c reduce the transition potential of high-grade urothelial carcinoma?

BACKGROUND: Bladder cancer is the leading transitional cell carcinoma affecting men and women with high morbidity and mortality rates, justifying the need to develop new molecular target therapies using microRNAs. This study aimed to evaluate the behavior of the T24 cell line after transfection with miR-Let-7c precursor mimic through invasion, migration, apoptosis, and cell cycle assays. METHODS AND RESULTS: T24 cell was transfected with the Let-7c mimic and its respective control and evaluated after 24 h. The expression levels of miR-Let-7c were analyzed by qPCR. We performed wound healing, Matrigel and flow cytometry, apoptosis, and cell cycle assays to determine its effect on cellular processes. Cells transfected with miR-Let-7c showed increased apoptosis rates (p = 0.019), decreased migration 24 h (p = 0.031) and 48 h (p = 0.0006), invasion potential (p = 0.0007), and cell proliferation (p = 0.002). CONCLUSIONS: Our results demonstrate that miR-Let-7c can act in different pathways of the carcinogenic cellular processes of muscle-invasive urothelial carcinoma cells, inhibiting cell proliferation and increasing apoptosis levels, consequently limiting their invasion potential. However, further studies should be carried out better to elucidate this microRNA's role in high-grade urothelial carcinomas and unveil which targets this microRNA may present, which are intrinsically related to the cancer survival pathways.