Comparisons of Major Cell-surface Proteins of Normal and Transformed Cells P H I L L I P S W. R O B B I N S , P H . D . Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139

ABSTRACT

I T IS CLEAR that important differences between the surfaces of normal and cancer cells exist. In considering the transformation of a cell from normal to tumorigenic, one would like to know what changes take place at the cell surface, how these changes occur, and what effects the surface changes have on the internal environment and social interactions of the cell. A perhaps too-obvious initial approach to the characterization of the key cell-surface changes is the comparative study of major cellsurface proteins a n d glycoproteins. Numerous experiments of this kind, many with established lines, have been reported, ~ : ~ " . ,„_. ,r UI. Received November 4, 1974; accepted for pubhca-

tion December 9, 1974.

However, a concern in such studies is the known aneuploidy of continuous lines and the tendency toward genetic drift under the twin pressures of unstable chromosome complement and continuous passaging in vitro. These objections can be overcome by using a system in which a diploid population of cells can be rapidly converted from the normal to the transformed phenotype by use of a transforming virus and use of corresponding virus mutants with a temperature-sensitive transforming function. We have used the TS-68 mutant of the Schmidt Ruppin strain of Rous sarcoma virus to transform secondary chick embryo fibroblasts. Fibroblasts so . _

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infected have normal morphology at 41 C.

Reprints of this entire Research Symposium are but are rapidly converted to a transavailable from the ASCP Meeting Services Depart- rf , • , i_-r»J ment, 2100 West Harrison Street, Chicago, Illinois °rmed morphology on shifting down to 60612, for $3.00 per copy. 36 C. 671

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Robbins, Phillips W.: Comparisons of major cell-surface proteins of normal and transformed cells. Am J Clin Pathol 63: 671-676, 1975. Transformation of the chick fibroblast surface has been studied in cells infected with Schmidt-Ruppin Rous sarcoma virus and the temperature-sensitive mutant of this virus, TS-68. Major findings following transformation induced by a shift from nonpermissive (41 C.) to permissive (36 C.) temperature in TS-68 infected cells were: (1) rapid cessation or slowing of the synthesis of a protein, M.W. 100-200,000, localization uncertain; (2) cessation or slowing of the synthesis of a plasma membrane protein, M.W. 45,000, within 2 - 4 hours; (3) cessation or slowing of the synthesis of a large trypsin- and collagenasesensitive protein (M.W. > 200,000) only after an extended period of morphologic transformation. In addition, increased quantities of type-specific viral antigen in the membranes of infected cells were observed in TS-68infected cells at 41 compared with 36 C. (Key words: Cell-surface proteins; Transformed cells.)

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Table 1. Characteristics of the Major Chick Cell Polypeptides That Decrease in Concentration Following Rous Sarcoma Virus Transformation

Protein

Nominal M.W.*

Cellular Location

Z

230,000

n

206,000

?

A

47,000

Plasma membranet

Extracellular

Glucosamine Labeling Yes

? Yes

Protease Sensitivity in Whole Cells

Time Required Lactoperoxidase- for Shut-off by Temperature catalyzed Shift in TS-68 Iodination in Infected Cells Whole Cells

Very sensitive to trypsin and collagenase

Yes

Days

Not sensitive

No

Comparisons of major cell-surface proteins of normal and transformed cells.

Comparisons of Major Cell-surface Proteins of Normal and Transformed Cells P H I L L I P S W. R O B B I N S , P H . D . Center for Cancer Research and...
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