Protein expression changes associated with radiation-induced neoplastic progression of human prostate epithelial cells.
Carcinogenic progression in most epithelial systems is a multistep process and presents as numerous (un)stable intermediate stages prior to the development of a fully malignant phenotype. Recently, we reported the neoplastic transformation of an SV40 immortalized, neonatal human prostate epithelial cell line (267B1) by multiple exposures to X-rays [1, 2]. The parental 267B1 cells acquired anchorage-independence and exhibited morphological transformation following exposure to two consecutive doses of 2 Gy. Exposure of either the parental 267B1 cells or the anchorage-independent derivatives (F3-SAC) to a total dose of 30 Gy of X-rays yielded tumorigenic transformants (267B1-XR and 267B1-SXR, respectively). All of these radiation-treated derivatives (F3-SAC, 267B1-XR, and 267B1-SXR) were characterized by reduced cell size and poorly organized actin stress fibers [2, 3]. The present study examines the protein expression changes associated with cytoskeletal alterations during the different steps of neoplastic progression induced by X-rays in the in vitro human prostate cell system. This analysis was achieved by using the high resolving power of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) in the 267B1, F3-SAC, 267B1-XR, and 267B1-SXR cells. We report changes in the expression of gelsolin in the partially transformed, anchorage-independent, nontumorigenic (F3-SAC) cells and a progressive loss of expression of tropomyosin isoforms (TM-1 and TM-3), and myosin light chain-2 (MLC-2) in the tumorigenic (267B1-XR; 267B1-SXR) cells, respectively. In contrast, our results demonstrate that the levels of the small GTP-binding protein Rho-A, an active participant in the actin stress fiber organization, are not altered during neoplastic progression of these 267B1 cells. Thus the changes in synthesis of gelsolin, tropomyosins, and MLC-2 provide a rationale for the alterations in the actin stress fiber formation and reduction in cell size during the exposure of prostate epithelial cells to multiple doses of X-rays.
Prasad
S C
SC
Department of Radiation Medicine, Vincent T. Lombardi Cancer Center, Georgetown University Medical Center, Washington, DC 20007-2197, USA. prasads@gunet.georgetown.edu
Thraves
P J
PJ
Dritschilo
A
A
Kuettel
M R
MR
D000199:Actins / Q000032:analysis; D002460:Cell Line; D002461:Cell Line, Transformed; D019204:GTP-Binding Proteins / Q000032:analysis; D018260:Gelsolin / Q000032:analysis; D006801:Humans; D008297:Male; D018994:Myosin Light Chains / Q000032:analysis; D011467:Prostate / Q000737:chemistry / Q000166:cytology / Q000528:radiation effects*; D011506:Proteins / Q000032:analysis*; D014335:Tropomyosin / Q000032:analysis; D014965:X-Rays; D020741:rho GTP-Binding Proteins
D000199:Actins; D018260:Gelsolin; D018994:Myosin Light Chains; D011506:Proteins; D014335:Tropomyosin; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins