In BMC Cancer this week, researchers in France report that ligand-free estrogen receptor activity works with IGF1R to induce proliferation in MCF-7 breast cancer cells. The team evaluated the effects of ER ligand agonist estradiol and the IGF1R ligand insulin in MCF-7 cells, and found that the activation of ER by estradiol doesn't induce cell cycle progression while PI3K/Akt signaling is blocked by a chemical inhibitor or by siRNA targeting Akt1 and Akt2. "siRNA-resistant Akt wild-type constructs efficiently complemented the mitogenic activity of [estradiol] whereas constructs with inactivated kinase function did not," the team writes. "In growth factor-starved cells, the residual PI3K/Akt activity is sufficient to complement the mitogenic action of E2." This suggests that basal ER activity in the absence of a ligand is sufficient to allow the mitogenic action of IGF1R agonists, they add.
Also in BMC Cancer this week, a team of researchers in China report that the transcription factor ZIC1 modulates cell-cycle distribution and cell migration by regulating the Sonic hedgehog, PI3K, and MAPK signaling pathways in gastric cancer. The team examined the role of ZIC1 in cell proliferation and migration, and found that over-expression of ZIC1 contributes to the inhibition of cell proliferation and migration as well as cell-cycle distribution in gastric cancer. They also identified "ZIC1 downstream targets by cDNA microarray analysis and revealed that 132 genes are down-regulated and 66 genes are up-regulated after transfection with ZIC1 in gastric cancer cells." These genes, the team adds, "play critical roles in cell proliferation, cell cycle and cell motility."
Finally in BMC Cancer this week, a Japanese research team reports on the expression of Bim, Noxa, and Puma in non-small-cell lung cancer. The team examined 135 surgically resected NSCLCs and found all three proteins in the cytoplasm of the tumor cells. Bim expression was associated with clinicopathological factors like sex, smoking habit, pathological histology, and differentiation of tumor, the team found. "Multivariate logistic regression analysis showed a significant correlation between low Bim expression and squamous cell carcinoma, in addition to a correlation between high Bim expression and well differentiated tumors," it adds. Noxa expression was also shown to be correlated with smoking habit and pathological histology, but not significantly. And there were no correlations between Puma expression and any clinical variables.