# ONCOGENE PHOSPHOINOSITIDE CYCLE/KINASE C

> **NIH NIH R01** · UNIVERSITY OF VERMONT & ST AGRIC COLLEGE · 1992 · $139,355

## Abstract

The overall goal of this proposal is to elucidate the role of
diacylglycerol (DAG) metabolism and of protein kinase C (PKC)
activity in oncogenic transformation.  DAG is the endogenous
activator of PKC, which is also the receptor for the tumor-
promoting phorbol esters.  This laboratory has proposed that some
oncogenes might transform cells by de-regulating DAG
metabolism, so as to constitutively activate PKC.  In support of
this hypothesis, DAG levels were found to be evaluated in
fibroblasts transformed by ras, src or fms and PKC was partially
activated.  Surprisingly, however, these transformed cells are also
partially densensitized to the effects of phorbol esters, and
revertant lines, resistant to transformation by v-ras, display a
more exaggerated desensitization.  These results suggest that
desensitization may represent an attempt by the cell to overcome
the constitutive proliferative signals generated by the oncogenes.

To determine the mechanism responsible for constitutive
elevation of DAG, metabolic labeling studies will be performed
using a 3T3 cell-line transfected with a temperature-sensitive v-
src oncogene.  Investigation of the control of DAG metabolism at
the molecular level will focus on DAG kinase, which has been
found to exist in multiple isotypes, and which translocates rapidly
to membranes in response to serum or phorbol esters.  Monoclonal
antibodies are being generated to the different isotypes to
facilitate studies of phosphorylation, tissue specificity and
processing.  Secondly, the kinetics and mechanism of PKC
desensitization will be determined.  (Is desensitization produced
by changes in phosphatase activity, PKC inhibitor production,
PKC phosphorylation, alterations in membrane association of PKC
or in the PKC substrates themselves?)  The role of PKC in the
mediation of transformation by v-src will also be investigated.
Phenotypic changes to be studied in detail include activation of c-
myc expression, initiation of DNA synthesis early changes in
protein phosphorylation and synthesis, and epidermal growth
factor (EGF) receptor down-modulation.  This last response
appears to be PKC-independent and involves two distinct,
separable mechanisms, one of which is cycloheximide-sensitive.
The role of other protein kinases, and of autocrine factors, in
promoting down-modulation will be elucidated, using both whole
cell and membrane preparations.  These experiments will provide
insight into the molecular mechanism by which certain oncogenes
mediate transformation, and the mechanism by which
transformation can be effectively blocked.

## Key facts

- **NIH application ID:** 3177313
- **Project number:** 5R01CA038888-09
- **Recipient organization:** UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
- **SAM.gov UEI:** Z94KLERAG5V9
- **Principal Investigator:** IAN G MACARA
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1992
- **Award amount:** $139,355
- **Award type:** 5
- **Project period:** 1991-06-01 → 1993-12-09

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3177313

## Citation

> US National Institutes of Health, RePORTER application 3177313, ONCOGENE PHOSPHOINOSITIDE CYCLE/KINASE C (5R01CA038888-09). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3177313. Licensed CC0.

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