Evidence of the cross talk between Wnt and Notch signaling pathways in non-small-cell lung cancer (NSCLC): Notch3-siRNA weakens the effect of LiCl on the cell cycle of NSCLC cell lines.

BACKGROUND

Aberrant activations of Wnt and Notch signaling pathways are individually reported to be associated with the pathogenesis of non-small-cell lung cancer (NSCLC). However, the data about the cross talk between the two signaling pathways are still limited. To elucidate potential Wnt/Notch cross talk within NSCLC, we examined the impact of Notch3 activity on LiCl-induced cell cycle changes.

METHODS

The lung cancer cell lines were treated with LiCl, a Wnt activator, in the absence or presence of Notch3-siRNA. Cell cycles and the expression of the regulators of cell cycle, c-MYC, p21 and Skp2 (S phase kinase-associated protein 2) were measured after treatment.

RESULTS

The treatment with LiCl increased the percent of cells at S phase and G phase and the expression of c-MYC and Skp2 and decreased the expression of p21. Moreover, the expression of Notch3 and its down-stream genes, HES-1 and HEYL, was up-regulated by LiCl. Notch3-siRNA weakened the effect of LiCl on the cell cycle and resulted in attenuation of the LiCl-induced increment of c-MYC and Skp2 and the LiCl-induced decrement of p21.

CONCLUSIONS

These data suggest that Notch3 activation cooperatively takes part in the LiCl-induced cell cycle changes, at least partially, associated with c-MYC, Skp2 and p21.