PURPOSE: Elevated IL-17 produced by T h 17 cells was reported to promote myeloma cell growth and inhibit immune function in multiple myeloma (MM). IL-17A was also reported to promote MM growth through IL-17 receptors and enhance adhesion to bone marrow stromal cells (BMSCs). Spleen tyrosine kinase (Syk) influences MM cell survival and migration. Herein we aimed to investigate whether Syk was involved in the regulative role of IL-17A in the viability of MM cells. METHODS: Cell viability was determined using CCK8 assay. The production of cytokine including IL-17A was evaluated with ELISA. Western blotting assay was used to determine protein expression levels of Syk and nuclear factor κB (NF-κB) related molecules. mRNA expression level of RORγt was detected with reverse transcription quantitative polymerase chain reaction. RESULTS: IL-17Awas highly expressed in MM patients and was able to induce MM cell viability. Following analysis indicated that the effects of IL-17A were mediated by Syk/ nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway. Immunoprecipitation also indicated that Syk is involved in IL-17A–induced Act1-TRAF6 complex formation and TRAF6 polyubiquitination in MM cells. CONCLUSIONS: Taken together, our study indicated that IL-17A increases MM cell viability through activating NF-κB signal pathway via positively regulating Syk expression. Syk also participates in the formation of IL-17R-proximal signaling complex (IL-17R-Act1-TRAF6), which is essential for IL-17A–mediated NF-kB activation. These investigations highlight that inhibition of Syk may be a potential therapeutic option for neoplastic diseases such as MM.

Hepatic stellate cells (HSC) and hydrogen sulfide (H2S) both play important roles in the development of hepatocellar carcinoma (HCC). Whereas, in the microenvironment of HCC, whether HSC participate in regulating the biological process of HCC cells by releasing H2S remains elusive. In vitro, Flow cytometry (FCM), CCK-8, RNA-sequencing, Western blotting, RT-qPCR, immunofluorescence and ChIP assays were carried out in the HCC cells to investigate the effect of H2S on biological functions and JNK/JunB-TNFSF14 signaling pathway. Specimens from HCC patients were analyzed by RT-qPCR and Western blotting assays for evaluating the expression of TNFSF14 and CSE. Statistical analysis was used to analyze the correlation between TNFSF14 expression and clinical data of HCC patients. Based on the FCM and CCK-8 results, we found the LX-2 cells were able to induce HCC cells apoptosis through releasing H2S. RNA-sequencing, RT-qPCR, and Western blotting results showed that TNFSF14 gene was upregulated in both LX-2 and NaHS group. NaHS treated in HCC cells led to JNK/JunB signaling pathway activating and greater binding of p-JunB to its responsive elements on TNFSF14 promoter. Impairment of TNFSF14 induction alleviated LX-2 and NaHS induced apoptosis of HepG2 and PLC/PRF/5 cells. Furthermore, TNFSF14 expression in HCC tissues was lower than the adjacent tissue. HCC patients with low expression of TNFSF14 had higher malignant degree and poor prognosis. In summary, demonstration of the involvement of HSC-derived H2S in JNK/JunB mediated expression of TNFSF14 gene strongly indicates H2S palys an important role in the regulation of HCC apoptosis.

Hepatocellular carcinoma (HCC) ranks sixth in population age-standardized incidence (ASI) and fourth in population age-standardized mortality (ASM) globally and is the fourth ASI and the second ASM, respectively, of the cancer spectrum in China. [1] HCC usually develops as a result of chronic hepatitis B, the major underlying etiology of HCC in China. Concerning the tumor microenvironment, a growing body of research has focused on the intercellular and molecular crosstalk between tumor cells and the surrounding hepatic stromal cells, including hepatic stellate cells (HSCs), liver stromal endothelial cells (LSECs), and immune cells. Among stromal cells, HSCs play a central role in the crosstalk between tumor and stroma, which contributes significantly to HCC progression.