Pathogenic mtDNA mutations associated with alterations of respiratory complex I, mitochondrial proliferation (oncocytic-like phenotype) and increase in antioxidant response were previously reported in type I endometrial carcinoma (EC). To evaluate whether in the presence of pathogenic mtDNA mutations other mitochondria] adaptive processes are triggered by cancer cells, the expression level of proteins involved in mitochondrial dynamics, mitophagy, proteolysis and apoptosis were evaluated in type I ECs harboring pathogenic mtDNA mutations and complex I deficiency. An increase in the fission protein Drpl, in the mitophagy protein BNIP3, in the mitochondrial protease CLPP, in the antioxidant and anti-apoptotic protein ALR and in Bcl-2 as well as a decrease in the fusion protein Mfn2 were found in cancer compared to matched non malignant tissue. Moreover, the level of these proteins was measured in type I EC, in hyperplastic (the premalignant form) and in non malignant tissues to verify whether the altered expression of these proteins is a common feature of endometrial cancer and of hyperplastic tissue. This analysis confirmed in type I EC samples, but not in hyperplasia, an alteration of the expression level of these proteins. These results suggest that in this cancer mitochondrial fission, antioxidant and anti-apoptotic response may be activated, as well as the discharge of damaged mitochondrial proteins as adaptation processes to mitochondrial dysfunction. (C) 2017 Elsevier Inc. All rights reserved.