Notch3 pathway mediates SAHA-induced apoptosis in human small-cell lung cancer H446 cells

AIM: To investigate the effect of suberoylanilide hydroxamic acid (SAHA) on the apoptosis of human small-cell lung cancer H446 cells and its possible mechanism. METHODS: H446 cells were incubated in the medium containing SAHA. CCK-8 assay was used to detect the anti-tumor effect of SAHA on the H446 cells, and IC₅₀ values of SAHA were calculated. Flow cytometry was used to analyze the apoptosis. After Notch3 gene was silenced, the pro-apopto-tic effect of SAHA on the H446 cells was inhibited (P<0.05). Eukaryotic expression plasmid containing N3ICD was transfected into the H446 cells, so that N3ICD was expressed in the H446 cells. The mRNA expression of Notch3 was measured by RT-PCR. The protein levels of Notch3, N3ICD, Puma and cleaved caspase-3 were determined by Western blot. RESULTS: SAHA remarkably reduced the cell viability in a dose-dependent manner (P<0.05), and the IC₅₀ value of SAHA was 1.91 μmol/L. SAHA induced apoptosis in a dose-dependent manner (P<0.05). The expression of Notch3 gene was negative in the H446 cells, SAHA reactivated Notch3 gene and Notch3 pathway in a dose-dependent manner (P<0.05).Notch3 knockdown inhibited apoptosis induced by SAHA (P<0.05). Over-expression of N3ICD up-regulated the protein levels of Puma and cleaved caspase-3.CONCLUSION: SAHA induces apoptosis in human small-cell lung cancer H446 cells by activating Notch3 pathway and up-regulating the protein level of Puma.