Leucine-rich protein 130 contributes to apoptosis resistance of human hepatocarcinoma cells.

LRP130 is a ubiquitous protein involved in cellular homeostasis, microtubule alteration, and transactivation of a few multidrug resistance genes. Its role in resistance to apoptosis in HepG2 and HUH7 hepatocarcinoma cells was investigated. Using shRNA-producing lentiviruses to down-regulate the LRP130 gene, we showed that i) LRP130 did not affect the capacity of hepatocarcinoma cells to extrude drugs since LRP130 down-regulation was insufficient to significantly reduce P-glycoprotein production in these cells, and ii) the expression of 11 apoptosis-related genes measured by PCR-array was significantly reduced. Interestingly, six of these genes encode extrinsic pathway proapoptotic proteins whose expression was higher in LRP130-non producing than in LRP130-producing HepG2 cells. Fluorescence microscopy confirmed this new anti-apoptotic role of LRP130, which is strengthened by a significantly reduced cytochrome c oxidase activity in LRP130-down-regulated hepatocarcinoma cells.