Direct tumorigenic conversion of human gallbladder carcinoma cells by v‐src but not by activated c‐H‐ras oncogene

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Abstract
The roles of activated ras and src oncogene products in the acquisition of fully neoplastic phenotype by human gallbladder adenocarcinoma cells were investigated by co‐transfecting non‐tumorigenic HAG‐1 human gallbladder carcinoma cells with the pSV2neo plasmid and a plasmid carrying either activated c‐H‐ras or v‐src oncogene. G‐418‐resistant clones were isolated and assessed for the acquisition of anchorage‐independent growth potential. Neither the 10 established clones transfected with pSV2neo alone nor the 17 clones transfected with activated c‐H‐ras, including 4 clones expressing the mutated p21H‐ras protein, could form colonies in soft agar. By contrast, out of 10 clones transfected with v‐src, 2 formed colonies in soft agar and produced tumors in athymic nude mice, the resulting progressive neoplasms being poorly differentiated adenocarcinomas. These tumorigenic clones were shown to have v‐src DNA and mRNA levels with p60v‐src protein, but there were no significant chromosomal alterations following tumorigenic conversion. Moreover, herbimycin A, a selective src‐kinase inhibitor, markedly reduced clonogenic growth of these cells in soft agar rather than monolayer growth, suggesting that anchorage‐independent growth of the v‐src‐transformed HAG‐1 cells might be driven directly by p60v‐src kinase activity. Taken together, our data suggest that the fully neoplastic conversion of HAG‐1 cells depends on src‐related tyrosine‐kinase activity, but not solely on the function mediated by activated ras, thus providing evidence of an src‐related signaling pathway for the acquisition of tumorigenic potential by human gallbladder adenocarcinoma cells. © 1995 Wiley‐Liss, Inc.