Tumor-associated macrophages (TAMs) promote tumor cell growth and metastasis in various human cancers. However, the role of TAMs in renal cell carcinoma (RCC) is rarely investigated. Herein, we observed that the infiltration of TAMs was obviously elevated in RCC tumor tissues, high infiltration of TAMs was closely associated with tumor progression and poor prognosis in RCC patients. In vitro assays further indicated that the conditioned medium of TAMs (TAMs CM) facilitated migration, invasion, and epithelial-mesenchymal transition (EMT) in RCC cells. Moreover, we found that IL-6 was involved in the functions of TAMs in RCC; IL-6 neutralizing antibody (IL-6NA) partly abolished the effect of TAMs on RCC cells. In addition, we demonstrated that TAMs might exert their roles by activating STAT3 signaling in RCC, and IL-6 was responsible for TAMs-induced STAT3 signaling activation. In conclusion, our results revealed that high infiltration of TAMs may promote RCC cells migration, invasion, and EMT via modulating IL-6/STAT3 signaling, further suggesting a potential of novel treatment strategies targeting TAMs or IL-6 for metastatic RCC.

Caspase-8 is a unique member of caspases with a dual role in cell death and survival. Caspase-8 expression is often lost in some tumors, but increased in others, indicating a potential pro-survival function in cancer. By analyzing transcriptome of enzalutamide-resistant prostate cancer cells, we found that resistance was conferred by a mild caspase-8 upregulation that in turn led to NF-κB activation and the subsequent upregulation of the downstream IL-8. Mechanistically, we found that the pro-survival and enzalutamide-resistance-promoting features of caspase-8 were independent of its proteolytic activity, using a catalytically-inactive caspase-8 mutant. We further demonstrated that caspase-8 pro-apoptotic function was inhibited via cFLIP binding. Moreover, high caspase-8 expression was correlated with a worse prognosis in prostate cancer patients. Collectively, our work demonstrates that enzalutamide-resistance is mediated by caspase-8 upregulation and the consequent increase in NF-κB/IL-8 mediated survival signaling, highlighting caspase-8 and NF-κB as potential therapeutic targets to overcome enzalutamide-resistance in CRPC.

Objective: To identify less invasive and easily applicable serum cytokine-derived biomarkers which contribute to the diagnostic utility and risk assessment ability of the prostate health index (PHI) based multivariable model in grey zone aggressive prostate cancer (AG PCa) early detection.Methods: Serum 45 cytokines screening was performed in a small training cohort consisting of 10 sera by Luminex liquid array-based multiplexed immunoassays and identified TRAIL and IL-10 as new biomarkers for PHI diagnostic utility adjustment for further validation with a multivariable predictive model in a cohort including 79 aggressive prostate cancer patients and 209 benign prostatic hyperplasia or indolent PCa patients within the PSA grey zone.Results: TRAIL and IL-10 were identified as potential serum biomarkers for AG PCa detection by the result of multi-cytokines screening in the univariate analysis, while multivariable logistic regression confirmed the AUC of the full risk predictive model (0.915) including tPSA, fPSA, PHI, TRAIL, and IL-10 was higher than various diagnostic strategies. DCA suggested a superior net benefit and indicated a good discriminative ability of the full risk model consistently with the result of the nomogram.Conclusion: We suggest a significant advantage for the PHI-based multivariate combinations of serum TRAIL and IL-10 comparing to PHI or other serum-derived biomarkers alone in the detection and risk stratification of grey zone AG PCa.