Oncogenic properties of a spermatogenic meiotic variant of Fer kinase expressed in somatic cells

The kinase Fer and its spermatogenic meiotic variant, FerT, are co-expressed in normal testes and cancerous tumors, but whether they exert related roles in spermatogenic or malignant cells has not been known. Here we show that Fer and FerT reside in the mitochondria of spermatogenic cells and are harnessed to the reprogrammed mitochondria of colon carcinoma (CC) cells. Both kinases bound complex I of the mitochondrial electron transport chain (ETC) in spermatogenic and in CC cells and silencing of either Fer or FerT was sufficient to impair the activity of this complex. Directed mitochondrial accumulation of FerT in non-malignant NIH3T3 cells increased their ETC complex I activity, ATP production and survival, contingent upon stress conditions caused by nutrient and oxygen deprivation. Strikingly, directed mitochondrial accumulation of FerT endowed non-malignant cells with tumor-forming ability. Thus, recruitment of a meiotic mitochondrial component to cancer cell mitochondria highlights a pivotal role for reprogrammed mitochondria in tumorigenesis.