Defined genetic events associated with the spontaneous in vitro transformation of ElA/Ras-expressing human IMR90 fibroblasts.
In contrast to rodent cells, normal human fibroblasts are generally resistant to neoplastic transformation in vitro. Here, we report the derivation and characterization of a spontaneously transformed cell line from normal human IMR90 fibroblasts transduced with E1A and Ras oncogenes. Unlike the parental, non-tumorigenic E1A/Ras-expressing IMR90 cells, these spontaneously transformed cells displayed aberrant growth potential in vitro and were capable of tumorigenesis in vivo. In contrast to the parental E1A/Ras-expressing cells, both the spontaneously transformed cells and cells derived from resultant tumors displayed specific t(7q;8q) and t(5q;17) structural chromosomal changes. Chromosome 8q contains c-Myc, which is capable of activating the telomerase catalytic subunit hTERT. Notably, upregulation of c-Myc, hTERT and telomerase activity were detected only in the tumorigenic cells. Transduction of Myc siRNA into the tumorigenic cells led to a concomitant downregulation of hTERT. Furthermore, transduction of Myc or hTERT into the non-tumorigenic E1A/Ras-expressing IMR90 cells was able to confer tumorigenesis on these cells. These studies suggest that the t(7;8) translocation may result in Myc overexpression and its subsequent activation of hTERT, which may contribute to the tumorigenicity of the IMR90 cells. Furthermore, this report describes additional successful neoplastic transformation of human IMR90 fibroblasts by defined genetic elements. The spontaneously transformed cells we have derived provide a valuable model system for the study of neoplastic transformation.
Mason
Douglas X
DX
Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
Keppler
Daniel
D
Zhang
Jun
J
Jackson
Tonya J
TJ
Seger
Yvette R
YR
Matsui
Seiichi
S
Abreo
Fleurette
F
Cowell
John K
JK
Hannon
Gregory J
GJ
Lowe
Scott W
SW
Lin
Athena W
AW
D017500:Adenovirus E1A Proteins / Q000502:physiology; D018929:Cell Culture Techniques; D002471:Cell Transformation, Neoplastic; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D005347:Fibroblasts; D005786:Gene Expression Regulation; D016259:Genes, myc; D011905:Genes, ras; D020022:Genetic Predisposition to Disease; D006801:Humans; D019098:Telomerase / Q000096:biosynthesis; D014161:Transduction, Genetic; D014178:Translocation, Genetic; D014407:Tumor Cells, Cultured
D017500:Adenovirus E1A Proteins; D004268:DNA-Binding Proteins; D019098:Telomerase