Curcumin induces p53-independent necrosis in H1299 cells via a mitochondria-associated pathway

Curcumin has been shown to have various therapeutic and/or adjuvant therapeutic effects on human cancers, as it inhibits cancer cell proliferation and induces apoptosis through p53-dependent molecular pathways. However, numerous cancer cell types bear a mutant p53 gene, and whether curcumin has any therapeutic effects on p53-deficient/mutant cancer cells has remained elusive. The present study sought to determine whether curcumin exerts any anti-proliferative and cytotoxic effects on the p53-deficient H1299 human lung cancer cell line via a p53-independent mechanism. An MTT assay and flow cytometric analysis indicated that curcumin significantly decreased cell proliferation and induced necrotic cell death. Western blot analysis of the cytosolic and mitochondrial fractions of H1299 cells as well as a fluorometric caspase assay indicated that curcumin-induced necrosis was mitochondria- and caspase-dependent, and resulted in cytochrome c release. Of note, this necrotic cell death was reduced following inhibition of B-cell lymphoma‑2 (Bcl-2)‑associated X protein (Bax) or Bcl‑2 homologous antagonist killer (Bak) as well as overexpression of Bcl-2. In conclusion, the present study suggested that curcumin-induced necrotic cell death was mediated via a p53-independent molecular pathway, which was associated with Bax and Bak translocation, caspase activation and cytochrome c release.