Why are transformed cells immortal? Is the process reversible?

James R. Smith, Yi Ning, Olivia M. Pereira-Smith

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Normal cells have finite proliferative potential in culture. In contrast, cells derived from tumors immortalized by chemical carcinogens or viruses are able to divide indefinitely. A question of major importance is the mechanism that limits the proliferative potential of normal cells, and conversely, the process by which immortal cells have escaped irreversible growth cessation. To address this question we fused a number of different normal human fibroblast cell lines with various immortal human cell lines and determined the proliferative behavior of the resulting hybrids. In all cases the hybrids had a limited ability to proliferate in culture. These results suggested that the finite proliferative capacity of normal human cells was dominant and that immortal cells had acquired recessive changes in their genetic program, which allowed them to escape senescence. We were also able to assign approximately 30 immortal human cell lines to four complementation groups for indefinite division.

Original languageEnglish (US)
Pages (from-to)1215S-1221S
JournalAmerican Journal of Clinical Nutrition
Issue numberSUPPL. 6
StatePublished - Jun 1992
Externally publishedYes


  • Cell aging
  • Immortalization and growth
  • Microcell hybrids
  • Programmed aging

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics


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