Shotgun approach based comparative proteomic analysis of levo-tetrahydropalmatine-induced apoptosis in hepatocytes.

The analgesic agent levo-tetrahydropalmatine (l-THP) was reported to be associated with acute or chronic hepatitis in clinical practice. We found that l-THP can induce apoptosis in the hepatocytes of BALB/c mice and human normal liver L-02 (L-02) cells. Several key molecules, including caspase-3, Bcl-2, BAD and Bax, were modulated by l-THP treatment. A novel high-throughput proteomic approach based on 2D-nano-LC-MS/MS was applied to simultaneously evaluate the alterations of global protein expression involved in the response of l-THP treatment in L-02 cells. A total of 156 deregulated proteins were identified, among which 12 proteins play regulatory or constitutive roles in the apoptosis pathways. Further analyses of two proteins (mTOR and MEK2) by Western Blots confirmed that these proteins were expressed at lower levels in l-THP-treated L-02 cells compared with those of control. The current study provided detailed evidence to support that l-THP is capable of inducing apoptosis in mammalian liver cells and improve the understanding of mechanisms of l-THP-induced hepatotoxicity.