ERK-regulated ?B-crystallin induction by matrix detachment inhibits anoikis and promotes lung metastasis in vivo.

ABSTRACT: Evasion of extracellular matrix detachment-induced apoptosis ('anoikis') is a defining characteristic of metastatic tumor cells. The ability of metastatic carcinoma cells to survive matrix detachment and escape anoikis enables them to disseminate as viable circulating tumor cells and seed distant organs. Here we report that ?B-crystallin, an antiapoptotic molecular chaperone implicated in the pathogenesis of diverse poor-prognosis solid tumors, is induced by matrix detachment and confers anoikis resistance. Specifically, we demonstrate that matrix detachment downregulates extracellular signal-regulated kinase (ERK) activity and increases ?B-crystallin protein and messenger RNA (mRNA) levels. Moreover, we show that ERK inhibition in adherent cancer cells mimics matrix detachment by increasing ?B-crystallin protein and mRNA levels, whereas constitutive ERK activation suppresses ?B-crystallin induction during matrix detachment. These findings indicate that ERK inhibition is both necessary and sufficient for ?B-crystallin induction by matrix detachment. To examine the functional consequences of ?B-crystallin induction in anoikis, we stably silenced ?B-crystallin in two different metastatic carcinoma cell lines. Strikingly, silencing ?B-crystallin increased matrix detachment-induced caspase activation and apoptosis but did not affect cell viability of adherent cancer cells. In addition, silencing ?B-crystallin in metastatic carcinoma cells reduced the number of viable circulating tumor cells and inhibited lung metastasis in two orthotopic models, but had little or no effect on primary tumor growth. Taken together, our findings point to ?B-crystallin as a novel regulator of anoikis resistance that is induced by matrix detachment-mediated suppression of ERK signaling and promotes lung metastasis. Our results also suggest that ?B-crystallin represents a promising molecular target for antimetastatic therapies.

SUBMITTER: Malin D 

PROVIDER: S-EPMC4537846 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature