Transfer of healthy fibroblast-derived mitochondria to HeLa ρ0 and SAS ρ0 cells recovers the proliferation capabilities of these cancer cells under conventional culture medium, but increase their sensitivity to cisplatin-induced apoptotic death.

Abstract

Mitochondrial dysfunction is known to contribute to cancer initiation, progression, and chemo-and radio-resistance. However, the precise role of mitochondria in cancer is controversial. Hence, here we tried to further clarify the role of mitochondria in cancer by transferring healthy mitochondria to cancer cells, and also to cells with depletedmitochondrialDNA (ρ0). Healthy mitochondria were isolated from WI-38 cellsand were transferred to HeLa, SAS, HeLa ρ0, and SAS ρ0 cells. Then, cell proliferation was verified. In addition, the cells were treated by different concentrations of cisplatin and assessed for apoptosis induction and quantifying the mRNA expressionof apoptosis-related genes. Results revealed that incubation of the HeLa,SAS and HeLaρ0 cells with 5µg/ml of the isolated mitochondria for 24h significantly (p < 0.001) increased cell proliferation compared to non-treated controls. Interestingly, the mitochondria transfer rescued the ρ0 cells and made them capable ofgrowing under conventional culture medium. However, the number of apoptotic cells wassignificantlyhigher in theHeLa ρ0 cells that received the mitochondria (HeLa-Fibro-Mit) compared to the HeLa ρ0. Furthermore, the expression level of BCL-2 anti-apoptotic gene was down-regulated in bothHeLa-Fibro-Mit andSAS-Fibro-Mit cell lines while the expression levels of the BAX,caspase8,caspase9, and AIFpro-apoptotic genes were upregulated. Our findings indicated that although the response of cancer cells to the mitochondria transfer is cancer-type dependent, but the introductionof normal exogenous mitochondria to some cancer cells might be considered as a potential novel therapeutic strategy.