Silodosin inhibits prostate cancer cell growth via ELK1 inactivation and enhances the cytotoxic activity of gemcitabine.

BACKGROUND: Biological significance of ELK1, a transcriptional factor whose phosphorylation is necessary for c-fos proto-oncogene activation, in prostate cancer remains far from fully understood. In this study, we aim to investigate the role of ELK1 in tumor growth as well as the efficacy of a selective α1A-adrenergic blocker, silodosin, in ELK1 activity in prostate cancer cells. METHODS: We first immunohistochemically determined the levels of phospho-ELK1 (p-ELK1) expression in radical prostatectomy specimens. We then assessed the effects of ELK1 knockdown via short hairpin RNA and silodosin on cell proliferation, migration, and invasion in prostate cancer lines. RESULTS: The levels of p-ELK1 expression were significantly higher in carcinoma than in benign (P < 0.001) or high-grade prostatic intraepithelial neoplasia (HGPIN) (P = 0.002) as well as in HGPIN than in benign (P < 0.001). Kaplan-Meier and log-rank tests revealed that moderate-strong positivity of p-ELK1 in carcinomas tended to correlate with biochemical recurrence after radical prostatectomy (P = 0.098). In PC3 and DU145 expressing ELK1 (mRNA/protein) but no androgen receptor (AR), ELK1 silencing resulted in considerable decreases in the expression of c-fos as well as in cell migration/invasion and matrix metalloproteinase-2 expression, but not in cell viability. Silodosin treatment reduced the expression/activity of ELK1 in these cells as well as the viability of AR-positive LNCaP and C4-2 cells and the migration of both AR-positive and AR-negative cells, but not the viability of AR-negative or ELK1-negative cells. Interestingly, silodosin significantly increased sensitivity to gemcitabine, but not to cisplatin or docetaxel, even in AR-negative cells. CONCLUSIONS: ELK1 is likely to be activated in prostate cancer cells and promote tumor progression. Furthermore, silodosin that inactivates ELK1 in prostate cancer cells not only inhibits their growth but also enhances the cytotoxic activity of gemcitabine. Thus, ELK1 inhibition has the potential of being a therapeutic approach for prostate cancer.

Shifting cold to hot tumors by nanoparticle-loaded drugs and products.

Cold tumors lack antitumor immunity and are resistant to therapy, representing a major challenge in cancer medicine. Because of the immunosuppressive spirit of the tumor microenvironment (TME), this form of tumor has a low response to immunotherapy, radiotherapy, and also chemotherapy. Cold tumors have low infiltration of immune cells and a high expression of co-inhibitory molecules, such as immune checkpoints and immunosuppressive molecules. Therefore, targeting TME and remodeling immunity in cold tumors can improve the chance of tumor repression after therapy. However, tumor stroma prevents the infiltration of inflammatory cells and hinders the penetration of diverse molecules and drugs. Nanoparticles are an intriguing tool for the delivery of immune modulatory agents and shifting cold to hot tumors. In this review article, we discuss the mechanisms underlying the ability of nanoparticles loaded with different drugs and products to modulate TME and enhance immune cell infiltration. We also focus on newest progresses in the design and development of nanoparticle-based strategies for changing cold to hot tumors. These include the use of nanoparticles for targeted delivery of immunomodulatory agents, such as cytokines, small molecules, and checkpoint inhibitors, and for co-delivery of chemotherapy drugs and immunomodulatory agents. Furthermore, we discuss the potential of nanoparticles for enhancing the efficacy of cancer vaccines and cell therapy for overcoming resistance to treatment.

Advancing therapeutic efficacy: nanovesicular delivery systems for medicinal plant-based therapeutics.

The utilization of medicinal plant extracts in therapeutics has been hindered by various challenges, including poor bioavailability and stability issues. Nanovesicular delivery systems have emerged as promising tools to overcome these limitations by enhancing the solubility, bioavailability, and targeted delivery of bioactive compounds from medicinal plants. This review explores the applications of nanovesicular delivery systems in antibacterial and anticancer therapeutics using medicinal plant extracts. We provide an overview of the bioactive compounds present in medicinal plants and their therapeutic properties, emphasizing the challenges associated with their utilization. Various types of nanovesicular delivery systems, including liposomes, niosomes, ethosomes, and solid lipid nanoparticles, among others, are discussed in detail, along with their potential applications in combating bacterial infections and cancer. The review highlights specific examples of antibacterial and anticancer activities demonstrated by these delivery systems against a range of pathogens and cancer types. Furthermore, we address the challenges and limitations associated with the scale-up, stability, toxicity, and regulatory considerations of nanovesicular delivery systems. Finally, future perspectives are outlined, focusing on emerging technologies, integration with personalized medicine, and potential collaborations to drive forward research in this field. Overall, this review underscores the potential of nanovesicular delivery systems for enhancing the therapeutic efficacy of medicinal plant extracts in antibacterial and anticancer applications, while identifying avenues for further research and development.

Silodosin inhibits the growth of bladder cancer cells and enhances the cytotoxic activity of cisplatin via ELK1 inactivation.

Silodosin, a selective α1A-adrenergic blocker prescribed for the symptomatic treatment of benign prostatic hyperplasia, was previously shown to decrease the expression of ELK1, a c-fos proto-oncogene regulator and a well-described downstream target of the PKC/Raf-1/ERK pathway, in human prostate smooth muscle cells. PKC/Raf-1/ERK activation has also been implicated in drug resistance. In the current study, we assessed the effects of silodosin on ELK1 expression/activity in bladder cancer cells as well as on their proliferation in the presence or absence of chemotherapeutic drugs, including cisplatin and gemcitabine. In bladder cancer cell lines, silodosin reduced the expression of ELK1 (mRNA/protein) and its downstream target, c-fos gene, as well as the transcriptional activity of ELK1. While silodosin alone (up to 10 µM) insignificantly affected the growth of bladder cancer cells cultured in androgen depleted conditions or those expressing ELK1-short hairpin RNA, it considerably inhibited the viability of androgen receptor (AR)-positive/ELK1-positive cells in the presence of androgens. Silodosin also inhibited the migration of ELK1-positive cells with or without a functional AR, but not that of ELK1 knockdown cells. Interestingly, silodosin treatment or ELK1 silencing resulted in increases in drug sensitivity to cisplatin, but not to gemcitabine, even in AR-negative cells or AR-positive cells cultured in an androgen-depleted condition. In addition, silodosin decreased the expression of NF-κB, a key regulator of chemoresistance, and its transcriptional activity. Moreover, immunohistochemistry in bladder cancer specimens from patients who received neoadjuvant chemotherapy revealed that phospho-ELK1 positivity strongly correlated with chemoresistance. Silodosin was thus found to not only inhibit cell viability and migration but also enhance the cytotoxic activity of cisplatin in bladder cancer lines via inactivating ELK1. Our results suggest that combined treatment with silodosin is useful for overcoming chemoresistance in patients with ELK1-positive urothelial carcinoma receiving cisplatin.

ELK1 is up-regulated by androgen in bladder cancer cells and promotes tumor progression.

Little is known about biological significance of ELK1, a transcriptional factor that activates downstream targets including c-fos proto-oncogene, in bladder cancer. Recent preclinical evidence also suggests the involvement of androgen receptor (AR) signaling in bladder cancer progression. In this study, we aim to investigate the functions of ELK1 in bladder cancer growth and their regulation by AR signals. Immunohistochemistry in bladder tumor specimens showed that the levels of phospho-ELK1 (p-ELK1) expression were significantly elevated in urothelial neoplasms, compared with non-neoplastic urothelium tissues, and were also correlated with AR positivity. Patients with p-ELK1-positive non-muscle-invasive and muscle-invasive tumors had significantly higher risks for tumor recurrence and progression, respectively. In AR-positive bladder cancer cell lines, dihydrotestosterone treatment increased ELK1 expression (mRNA, protein) and its nuclear translocation, ELK1 transcriptional activity, and c-fos expression, which was restored by an anti-androgen hydroxyflutamide. ELK1 silencing via short hairpin RNA (shRNA) resulted in decreases in cell viability/colony formation, and cell migration/invasion as well as an increase in apoptosis. Importantly, ELK1 appears to require activated AR to regulate bladder cancer cell proliferation, but not cell migration. Androgen also failed to significantly induce AR transactivation in ELK1-knockdown cells. In accordance with our in vitro findings, ELK1-shRNA expression considerably retarded tumor formation as well as its growth in xenograft-bearing male mice. Our results suggest that ELK1 plays an important role in bladder tumorigenesis and cancer progression, which is further induced by AR activation. Accordingly, ELK1 inhibition, together with AR inactivation, has the potential of being a therapeutic approach for bladder cancer.