A tumor-suppressing protein called alpha-catenin appears to stop the development of squamous cell carcinoma by keeping another protein—the cancer-causing Yap1—in check. 

Valeri Vasioukhin, PhD, of the University of Washington and Fred Hutchinson Cancer Research Center in Seattle, and colleagues studied mice that had been bred to lack a copy of the p53 gene, which encodes for alpha-catenin in the stem cells of hair follicles. The mice subsequently developed squamous cell carcinoma, indicating that alpha-catenin functions as a tumor suppressor. In addition, the alpha-catenin-mutant cells exhibited a hallmark characteristic of cancer cells by dividing continuously even in a very crowded Petri dish.

Further study by the scientists revealed that alpha-catenin controls the activity of another protein, Yap1, which can cause cancer if activated—making Yap1 a likely strong target in the treatment of squamous cell carcinoma.

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“We found an inverse correlation between [alpha-catenin] abundance and Yap1 activation in human squamous cell carcinoma tumors,” affirmed the investigators in Science Signaling (2011;4[174]:ra33). “These findings identify [alpha-catenin] as a tumor suppressor that inhibits Yap1 activity and sequesters it in the cytoplasm.”