A novel oncogenic BTK isoform is overexpressed in colon cancers and required for RAS-mediated transformation

作者：Grassilli E^*; Pisano F; Cialdella A; Bonomo S; Missaglia C; Cerrito M G; Masiero L; Ianzano L; Giordano F; Cicirelli V; Narloch R; D'Amato F; Noli B; Ferri G L; Leone B E; Stanta G; Bonin S; Helin K; Giovannoni R; Lavitrano M^*

来源：Oncogene, 2016, 35(33): 4368-4378.

DOI：10.1038/onc.2015.504

Bruton's tyrosine kinase (BTK) is essential for B-cell proliferation/differentiation and it is generally believed that its expression and function are limited to bone marrow-derived cells. Here, we report the identification and characterization of p65BTK, a novel isoform abundantly expressed in colon carcinoma cell lines and tumour tissue samples. p65BTK protein is expressed, through heterogeneous nuclear ribonucleoprotein K (hnRNPK)-dependent and internal ribosome entry site-driven translation, from a transcript containing an alternative first exon in the 5'-untranslated region, and is post-transcriptionally regulated, via hnRNPK, by the mitogen-activated protein kinase (MAPK) pathway. p65BTK is endowed with strong transforming activity that depends on active signal-regulated protein kinases-1/2 (ERK1/2) and its inhibition abolishes RAS transforming activity. Accordingly, p65BTK overexpression in colon cancer tissues correlates with ERK1/2 activation. Moreover, p65BTK inhibition affects growth and survival of colon cancer cells. Our data reveal that BTK, via p65BTK expression, is a novel and powerful oncogene acting downstream of the RAS/MAPK pathway and suggest that its targeting may be a promising therapeutic approach.

• 出版日期2016-8