Induced terminal differentiation and tumorigenic suppression in murine keratinocyte somatic‐cell hybrids

Brandt L. Schneider, Molly Kulesz‐Martin, G. Tim Bowden

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


The development of malignancy has been associated with both the activation of oncogenes and the inactivation of tumor suppressor genes. Whereas recent data implicate tumor suppressor genes as cell‐cycle checkpoints, the nature and timing of tumor suppressor gene inactivation during multistage carcinogenesis is still largely uncharacterized. To address this issue, we used a syngeneic mouse epidermal model system. By creating somatic‐cell hybrids between nontumorigenic × benign (291 × 291.09RAT), nontumorigenic × malignant (291 × 291.05RAT and 291 × 291.03RAT), benign × malignant (291.09RAT × 291.03RAT) and malignant × malignant (291.03RAT × 291.05RAT) clones, multiple tumor suppressor activities were detected. Most importantly, we demonstrated the first example of the complete suppression of benign papillomas in vivo, thus implicating tumor suppressor gene activity loss as an early event in skin carcinogenesis. In addition, the carcinoma phenotype was suppressed in vivo by nontumorigenic, benign, and heterologous malignant keratinocytes. The somatic‐cell hybrids expressed the differentiation‐specific keratins, K1 and K10, in response to high extracellular calcium concentrations (1.4 mM) in vitro. All of the hybrids had fewer local metastases than did the parental lines, and when tumor formation was not suppressed, the resulting tumors were highly differentiated. Polymerase chain reaction analysis of the neomycin‐resistance gene at nontumorigenic injection sites indicated an absence of injected hybrids, and subsequent analyses failed to detect nontumorigenic 291 cells 1 wk after transplantation. These data demonstrate that distinct tumor suppressor gene activities are lost at discrete stages during multistage carcinogenesis and are consistent with the hypothesis that tumor suppression can occur through induction of terminal differentiation. © 1995 Wiley‐Liss, Inc.

Original languageEnglish (US)
Pages (from-to)6-14
Number of pages9
JournalMolecular Carcinogenesis
Issue number1
StatePublished - May 1995
Externally publishedYes


  • Tumor suppressor
  • carcinogenesis
  • epidermis

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research


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