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Tumorigenicity of Human Breast Cancer Is Associated with Loss of the Ca21- activated Chloride Channel CLCA2

The human Ca21-activated chloride channel-2 (CLCA2) is expressed in
normal breast epithelium but not in breast tumors of different stages of
progression. Northern analysis of nontransformed and transformed
breast epithelial cell lines revealed CLCA2 expression in the nontransformed
cell line MCF10A and the nontumorigenic cell line MDA-MB-453,
whereas all tumorigenic cell lines were negative (MDA-MB-231, MDAMB-
435, MDA-MB-468, and MCF7). When stably reintroduced into
CLCA2-negative MDA-MB-231 and MDA-MB-435 cells, CLCA2 expression
reduced Matrigel invasion in vitro and inducibility of s.c. and metastatic
tumors of MDA-MB-231 cells in nude mice. Our results suggest that
CLCA2 may act as a tumor suppressor in breast cancer.