Enhanced expression of cyclooxygenase-2 related multi-drug resistance gene in melanoma and osteosarcoma cell lines by TSG-6 secreted from canine adipose-derived mesenchymal stem/stromal cells.

BACKGROUND: Multiple drug resistance (MDR) of cancer cells is the main cause of intrinsic or acquired desensitization to chemotherapy in many cancers. A number of studies have found high expression of COX-2 to be a factor for expression of MDR gene in several cancer. Furthermore, adipose tissue derived mesenchymal stem/stromal cells (ADSC) have been found to increase cyclo-oxygenase-2 (COX-2) expression in some tumour cells. The mechanism for this, however, is not yet clear and needs further study. OBJECTIVE: The purpose of this study was to determine whether tumour necrosis factor-alpha stimulated gene/protein 6 (TSG-6) secreted from ADSCs is associated with an increase in MDR genes by inducing COX-2 gene expression in melanoma and osteosarcoma cell lines. METHODS: ADSCs were transfected with TSG-6 siRNA or Control RNA respected, and cancer cell line were transfected with COX-2 siRNA or Control RNA respected. Using trans well coculture system, the interactions of ADSCs with tumour cells were investigated. RESULTS: Increased COX-2 expression was observed in cancer cell co-cultured with ADSCs. Additionally, we identified that COX-2 expression was related to drug resistance genes (P-glycoprotein, multidrug resistance-associated protein). Transfecting canine ADSCs with small interfering RNA, TSG-6 secreted from ADSCs was found to be a major factor in the regulation of COX-2 expression and drug resistance genes in osteosarcoma and melanoma cell lines. CONCLUSION: TSG-6 mediated COX-2 up-regulation is a possible mechanism of chemoresistance development induced by ADSCs. These findings provide better understanding about the mechanism associated with ADSC-induced chemoresistance in cancer.

Influence of Canine Macrophage-derived Extracellular Vesicles on Apoptosis in Canine Melanoma and Osteosarcoma Cell Lines.

BACKGROUND/AIM: The purpose of this study was to evaluate the effect of extracellular vesicles derived from canine M1-polarized macrophages (M1EVs) on canine tumor cells, such as D17 (osteosarcoma cells) and LMeC (melanoma cells). MATERIALS AND METHODS: Protein expression was determined by western blot analysis. Gene expression was determined by RT-qPCR. In addition, cell apoptosis was analyzed by Annexin V/PI staining. RESULTS: In the case of M1EV, the levels of pro-inflammatory cytokines such as TNF-α, IL-6 and IL-1ß were increased, and nitrate/nitrite levels were also increased. M1EV induced apoptosis of tumor cells by increasing caspase-3 and caspase-7 activation. In addition, M1EVs decreased expression of CCR4, Foxp3 and CTLA-4 in canine peripheral mononuclear cells cocultured with tumor cells. CONCLUSION: M1EV could be an effective anti-cancer therapeutic approach in melanoma and osteosarcoma and M1EVs can be used as immunomodulators in the tumor microenvironment for cancer treatment.