Background: The chemoresistance of prostate cancer (PCa) is invariably associated with the aggressiveness and metastasis of this disease. New emerging evidence indicates that the epithelial-to-mesenchymal transition (EMT) may play pivotal roles in the development of chemoresistance and metastasis. As a hallmark of EMT, E-cadherin is suggested to be a key marker in the development of chemoresistance. However, the molecular mechanisms underlying PCa chemoresistance remain unclear. The current study aimed to explore the association between EMT and chemoresistance in PCa as well as whether changing the expression of E-cadherin would affect PCa chemoresistance.Methods: Parental PC3 and DU145 cells and their chemoresistant PC3-TxR and DU145-TxR cells were analyzed. PC3-TxR and DU145-TxR cells were transfected with E-cadherin-expressing lentivirus to overexpress E-cadherin; PC3 and DU145 cells were transfected with small interfering RNA to silence E-cadherin. Changes of EMT phenotype-related markers and signaling pathways were assessed by Western blotting and quantitative real-time polymerase chain reaction. Tumor cell migration, invasion, and colony formation were then evaluated by wound healing, transwell, and colony formation assays, respectively. The drug sensitivity was evaluated using MTS assay.Results: Chemoresistant PC3-TxR and DU145-TxR cells exhibited an invasive and metastatic phenotype that associated with EMT, including the down-regulation of E-cadherin and up-regulation of Vimentin, Snail, and N-cadherin,comparing with that of parental PC3 and DU145 cells. When E-cadherin was overexpressed in PC3-TxR and DU145-TxR cells, the expression of Vimentin and Claudin-1 was down-regulated, and tumor cell migration and invasion were inhibited. In particular, the sensitivity to paclitaxel was reactivated in E-cadherin-overexpressing PC3-TxR and DU145-TxR cells. When E-cadherin expression was silenced in parental PC3 and DU145 cells, the expression of Vimentin and Snail was up-regulated, and, particularly, the sensitivity to paclitaxel was decreased. Interestingly, Notch-1 expression was up-regulated in PC3-TxR and DU145-TxR cells, whereas the E-cadherin expression was down-regulated in these cells comparing with their parental cells. The use of γ-secretase inhibitor, a Notch signaling pathway inhibitor, significantly increased the sensitivity of chemoresistant cells to paclitaxel.Conclusion: The down-regulation of E-cadherin enhances PCa chemoresistance via Notch signaling, and inhibiting the Notch signaling pathway may reverse PCa chemoresistance

Prostate cancer tissue is composed of both cancer cells and host cells. The milieu of host components that compose the tumor is termed the tumor microenvironment (TME). Host cells can be those derived from the tissue in which the tumor originates (e.g., fibroblasts and endothelial cells) or those recruited, through chemotactic or other factors,to the tumor (e.g., circulating immune cells). Some immune cells are key players in the TME and represent a large proportion of non-tumor cells found within the tumor. Immune cells can have both anti-tumor and pro-tumor activity.In addition, crosstalk between prostate cancer cells and immune cells affects immune cell functions. In this review,we focus on immune cells and cytokines that contribute to tumor progression. We discuss T-regulatory and T helper 17 cells and macrophages as key modulators in prostate cancer progression. In addition, we discuss the roles of interleukin-6 and receptor activator of nuclear factor kappa-B ligand in modulating prostate cancer progression. This review highlights the concept that immune cells and cytokines offer a potentially promising target for prostate cancer therapy.

Background: Some of the active perianal fistulizing Crohn's disease (CD) patients achieving remission with infliximab (IFX) therapy would develop relapse of perianal fistula within weeks to years after discontinuation of IFX therapy. Aims: To assess the outcomes of patients with perianal fistulizing CD after discontinuation of IFX therapy and the risk factors for relapse of perianal fistula. Methods: The clinical data of patients with perianal fistulizing CD who received IFX therapy at Shanghai Renji Hospital between June 2013 and May 2019 and stopped IFX therapy after achieving complete or partial radiological remission were collected retrospectively and analyzed. Demographic data, clinical and imaging characteristics, as well as data of IFX treatment and relapse of perianal fistula were extracted. Kaplan-Meier analysis was performed to calculate the cumulative probabilities of perianal and luminal relapse, while Cox proportional hazards model was applied to identify the risk factors for relapse. Results: A total of 56 perianal fistulizing CD patients who had been treated with IFX and stopped IFX therapy were included. Of them 26 achieved complete radiological remission and 30 achieved partial radiological remission. The median follow-up time was 20.5 months. Twenty-one patients (37.5%) had relapse of perianal fistula. The cumulative probabilities of perianal relapse were 29.0%, 33.7% and 42.8% at 12, 24 and 60 months after IFX discontinuation, respectively; and the cumulative probabilities of luminal relapse were 21.7%, 31.2% and 56.4% at 12, 24 and 60 months after IFX discontinuation, respectively. Multivariate analysis showed that non-stricturing and non-penetrating type (HR=9.711, 95% CI: 1.210-77.939, P=0.032) and involvement of rectum (HR=3.034, 95% CI: 1.119-8.231, P=0.029) were independent risk factors for relapse of perianal fistula, while the frequency of using of IFX therapy was a protective factor (HR=0.885, 95% CI: 0.792-0.990, P=0.032). Conclusions: There is a high risk of relapse of perianal fistulizing CD after discontinuation of IFX therapy. Non-stricturing and non-penetrating type and rectal involvement are risk factors for relapse of perianal fistula, and increasing the frequencies of using IFX therapy is crucial for the maintenance of remission.