The involvement and possible targeting of cardiolipins degradation and disturbed linoleic acid metabolism in cardiac atrophy under cancer cachexia

Cardiac atrophy is one of the critical characteristics of cancer cachexia though its mechanisms had not been fully clarified. In the present study, to study the mechanisms of cardiac atrophy in cancer cachexia and search for possible drug targets, cancer cachexia mice bearing C26 colon tumor cells and cultured H9c2 cardiomyocytes induced with simulated cancer cachexia injuries were used as in vivo and in vitro model, respectively. Results of both spatial metabolomics and LC-MS non-targeted metabolomics analysis of heart tissues suggested the disturbance of glycerophospholipid and fatty acid metabolism in the cancer cachexia hearts. Results of lipidomic analysis confirmed that the fatty acid composition of glycerophospholipids changed and the levels of linoleic acid (LA)-rich cardiolipins (CLs) significantly decreased. GC-MS analysis of fatty acids profile confirmed that the level of LA significantly increased and the ratio value of ω-6/ω-3 polyunsaturated fatty acids (PUFA) also increased in the cancer cachexia hearts. In H9c2 cardiomyocytes induced by simulated cancer cachexia injuries, degradation of CLs were also observed. Furthermore, SS-31, a tetrapeptide targeting CLs, could protect the H9c2 cardiomyocytes under simulated cancer cachexia injury by ameliorating the degradation of CLs, inhibiting apoptosis and attenuating the decrease in cell size. Collectively, these results have provided new insights into the cardiac atrophy in cancer cachexia, in which degradation of glycerophospholipids such as CLs and increase in LA and AA-related oxylipins might be important contributing factors and possible therapy targets.