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Quantitative changes in cytoskeletal and nuclear actins during cellular transformation.

Authors
Rao-JY; Bonner-RB; Hurst-RE; Liang-YY; Reznikoff-CA; Hemstreet-GP
Source
Int J Cancer 1997 Feb; 70(4):423-429
NIOSHTIC No.
20031027
Abstract
Actin, a highly conserved protein comprising cell stress fibers and other cellular structures, is found in both the cytoplasm and nucleus of cells and responds to both epigenetic signals and altered gene expression occurring during tumorigenesis. We have previously shown that changes in the cytoplasmic F- and G-actin ratios reflect bladder cancer risk. To determine whether nuclear actin is also altered and how nuclear and cytoplasmic actin alterations are interrelated in transformation, an in vitro model of carcinogen-induced transformation consisting of 2 human uroepithelial cell lines immortalized by infection with SV-40 was studied. One line, HUC-PC, is tumorigenic in nude mice after incubation with the carcinogen 4-ABP, the other, HUC-BC, is not. Cytoplasmic and nuclear F- and G-actin were determined by QFIA on individual cells using fluorochrome-labeled phallicidin and DNase, I, respectively. Before exposure to 4-ABP, the PC cells had lower cytoplasmic F-actin content, higher cytoplasmic G-actin content, but similar levels of nuclear G- and F-actin in comparison to the BC cells. After incubation with 4-ABP, F-actin decreased and G-actin increased in both cytoplasm and nuclei of PC cells and cytoplasmic F-actin fibers were lost, but only cytoplasmic actin was altered in the BC cells. Northern blot analysis showed the expression of the beta-actin gene was only approximately 20% lower in 4-ABP-treated PC cells than in untreated controls, indicating the cellular change in actin was attributed to a shift between F- and G-actin proteins rather than to net actin synthesis.
Keywords
Proteins; Tumorigens; Tumorigenesis; Cellular-structures; Cancer; Risk-factors; Risk-analysis; Bladder-cancer; Carcinogens; Carcinogenicity; Carcinogenesis; In-vitro-studies; Models; Laboratory-animals; Animals; Animal-studies; Cell-transformation
Contact
George P. Hemstreet III, Department of Urology, University of Oklahoma Health Sciences Center, 920 Stanton L. Young Boulevard, Oklahoma City, OK 73190, USA
CODEN
IJCNAW
CAS No.
67-68-5; 92-67-1
Publication Date
19970207
Document Type
Journal Article
Funding Amount
1994426
Funding Type
Grant
Fiscal Year
1997
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-002647
Issue of Publication
4
ISSN
0020-7136
Source Name
International Journal of Cancer
State
OK
Performing Organization
University of Oklahoma Hlth Sciences Ctr, Oklahoma City, Oklahoma
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