# TUMOR PROMOTER EFFECTS UPON INITIATED CELL COMMUNICATION

> **NIH NIH R01** · UNIVERSITY OF HAWAII AT MANOA · 1987 · $83,170

## Abstract

Substances with tumor promoting activity, especially certain phorbol
esters, have been shown to interrupt junctional intercellular
communication.  It is not known if this effect has any significance to the
enhancement of tumor formation.  In preliminary studies, TPA was found to
significantly increase the percentage of small colonies (less than 200
cells) forming transformed foci in cultures of carcinogen initiated C3H/10T
1/2 cells in which transformation is dependent upon the number of cells in
the initiated cell colony at confluence.  TPA also inhibited the rescue
from ouabain toxicity of initiated 10T 1/2 cells by ouabain-resistant
normal cells.  Since dibutaryl cyclic AMP was found to inhibit the
transformation of initiated 10T 1/2 cells, it is proposed that the
junctional intercellular communication of cAMP from normal to initiated
cells can suppress transformation.  The interruption of this cell-cell
interaction by TPA thus permits and/or stimulates transformation.  To
further test this hypothesis experiments are described to determine the
effect of tumor promoters on 1) colony size dependence of C3H/10T 1/2 cell
transformation, 2) on rescue of ouabain sensitive initiated cells by
ouabain-resistant normal cells, 3) on the intercellular transfer of
6-carboxyfluorescein, and 4) on the phosphorylation of the 27,000D major
gap-junction protein.  The results of these experiments should provide
valuable information about the role of intercellular communication in the
modulation of neoplastic transformation and the role of tumor promoters and
aberrant function of the gap junction in modulating preneoplastic
progression to transformation.

## Key facts

- **NIH application ID:** 3177125
- **Project number:** 5R01CA038806-03
- **Recipient organization:** UNIVERSITY OF HAWAII AT MANOA
- **SAM.gov UEI:** NSCKLFSSABF2
- **Principal Investigator:** LAWRENCE J MORDAN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1987
- **Award amount:** $83,170
- **Award type:** 5
- **Project period:** 1985-09-01 → 1988-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3177125

## Citation

> US National Institutes of Health, RePORTER application 3177125, TUMOR PROMOTER EFFECTS UPON INITIATED CELL COMMUNICATION (5R01CA038806-03). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3177125. Licensed CC0.

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