Background Previous studies have demonstrated that transcription factor SOX9 which was reactivated in prostate cancer (Pca) and promoted tumor growth was a poor prognostic biomarker for Pca. Nevertheless, the regulatory mechanism underlying SOX9 upregulation in Pca still remains unclear. Several cytokines widely distributed in the tumor microenvironment (TME) have been reported to be involved in the regulation of SOX9, suggesting that cancer-associated fibroblasts (CAFs), one of the main sources of secreted factors in TME, may play a role in regulating SOX9 expression. Methods Herein, an in vitro model of paracrine interaction between primary CAFs and Pca cells (both AR-positive and AR-negative Pca cells), was applied to investigate the molecular mechanism of SOX9 upregulation during Pca progression. The regulatory axis was validated by in vivo experiments and The Cancer Genome Atlas (TCGA) data. Results Conditional medium from Pca CAFs (CAF-CM) upregulated the expression of SOX9, which was also proved to be essential for CAF-induced tumor progression. Further analysis showed that it was hepatocyte growth factor (HGF) secreted by CAFs that was responsible for the SOX9 elevation in Pca cells via activating c-Met signaling. Mechanistically, HGF/c-Met signaling specifically activated MEK1/2-ERK1/2 pathway which then induced phosphorylated status and protein upregulation of FRA1. Furthermore, ChIP assay demonstrated that FRA1 transcriptionally upregulated SOX9 expression by binding to the TPA-responsive element (TRE) sequence in the promoter of SOX9 gene. We also found that HGF/c-Met-ERK1/2-FRA1-SOX9 axis was relatively conserved in human and mouse species by validating in mouse Pca cells (RM-1). Conclusions Our results revealed a novel insight into the molecular mechanism that SOX9 expression in Pca cells is promoted by CAFs, through the HGF/cMet-ERK1/2-FRA1 axis. Besides, SOX9 may serve as an alternative marker for the activated HGF/c-Met signaling to enroll the optimal Pca patients for HGF/c-Met inhibition treatment, since it is much more stable and easier to detect.

The mechanisms underlying the effects of cancer-associated fibroblasts (CAFs) on cancer stemness and tumor progression in renal cell carcinoma (RCC) have not been elucidated yet. In the present study, we found that the enrichment of CAFs was positively associated with tumor progression and cancer stemness in RCC. Further investigation revealed that CAFs could enhance cancer stemness through delivering exosomes to RCC cells, and miR-181d-5p was identified as the critical exosomal miRNA in CAF secreted exosomes by small RNA sequencing and subsequent screening assays. Mechanistically, exosomal miR-181d-5p transferred from CAFs to RCC cells directly suppressed the expression of ring finger protein 43 (RNF43) and activated Wnt/β-catenin signaling pathway, thus promoted cancer stemness and tumor progression. Overexpression of RNF43 strongly suppressed stemness properties and the effects could be reverted by miR-181d-5p. Overall, our findings revealed a crucial mechanism by which CAFs secreted exosomal miRNAs to enhance cancer stemness and thus promote RCC progression, suggesting a new avenue based on CAF secreted miRNAs for more effective targeted therapies.

Chemotherapy is a standard cancer treatment which uses anti-cancer drugs to destroy or slow the growth of cancer cells. However, chemotherapy has limited therapeutic effects in bladder cancer. One of the reasons of this resistance to chemotherapy is that higher levels of glutathione in invasive bladder cancer cells. We have fabricated nanoparticles that respond to high concentrations of glutathione and near-infrared laser irradiation in order to increase the drug accumulation at the tumor sites and combine chemotherapy with photothermal therapy to overcome the challenges of bladder cancer treatment.Methods:The DOX&IR780@PEG-PCL-SS NPs were prepared by co-precipitation method. We investigated the tumor targeting capability of NPs in vitro and in vivo. The orthotopic bladder cancer model in C57BL/6 mice was established for in vivo study and the photothermal effects and therapeutic efficacy of NPs were evaluated.Results:The DOX&IR780@PEG-PCL-SS NPs were synthesized using internal cross-linking strategy to increase the stability of nanoparticles. Nanoparticles can be ingested by tumor cells in a short time. The DOX&IR780@PEG-PCL-SS NPs have dual sensitivity to high levels of glutathione in bladder cancer cells and near-infrared laser irradiation. Glutathione triggers chemical structural changes of nanoparticles and preliminarily releases drugs, Near-infrared laser irradiation can promote the complete release of the drugs from the nanoparticles and induce a photothermal effect, leading to destroying the tumor cells. Given the excellent tumor-targeting ability and negligible toxicity to normal tissue, DOX&IR780@PEG-PCL-SS NPs can greatly increase the concentration of the anti-cancer drugs in tumor cells. The mice treated with DOX&IR780@PEG-PCL-SS NPs have a significant reduction in tumor volume. The DOX&IR780@PEG-PCL-SS NPs can be tracked by in vivo imaging system and have good tumor targeting ability, to facilitate our assessment during the experiment.Conclusion:A nanoparticle delivery system with dual sensitivity to glutathione and near-infrared laser irradiation was developed for delivering IR780 and DOX. Chemo-photothermal synergistic therapy of both primary bladder cancer and their metastases was achieved using this advanced delivery system.