Project Details


cis-Diamminedichloroplatinum (II) (CP) is one of the most important
antineoplastic agents used to treat solid tumors. The bases of its
selective toxicity to tumor tissue and development of resistance by
malignant tissue to CP are incompletely understood. The overall objective
of this grant proposal is to determine the biochemical mechanisms by which
signal transduction pathways control the antitumor activity of CP and to
develop strategies to improve the therapeutic efficacy of CP.
Specifically, I intend to use human cervical cancer (HeLa) cells that are
sensitive and resistant to CP to investigate how protein kinase C (PKC), a
key signal transducing element, regulates the antiproliferative activity of
CP. The Specific Aims and the methodologies to be used are as follows:

1. Determine the effects of PKC inhibitors on cellular sensitization to
CP. The ability of PKC inhibitors to decrease CP sensitivity or to
antagonize PKC activator-mediated CP sensitization will be investigate by
using novel synthetic inhibitors of PKC or monoclonal antibody to PKC.

2. Elucidate the role of PKC isoforms in the drug sensitization
phenomenon. The contribution of a particular isoform of PKC in the drug
sensitization phenomenon will be investigated by comparing: (i) the change
in expression of PKC isoforms induced by agents that sensitize cells to CP,
(ii) cell-type specific expression of isoforms either constitutively or
following treatment with PKC activators, and (iii) CP sensitivity of cells
that overexpress a specific PKC isoform due to introduction of expression
vector containing PKC cDNA corresponding to the alpha, beta or gamma

3. Elucidate the mechanism(s) of PKC-mediated sensitization to CP. The
functional significance of PKC-mediated sensitization to CP will be
investigated by studying the effects of specific PKC activators and
inhibitors on: (i) cellular drug accumulation (uptake and efflux), (ii)
subcellular distribution, and (iii) DNA damage and repair.

4. Determine if phosphorylation of a specific protein is involved in PKC-
mediated cellular sensitization to CP. Protein phosphorylation will be
examined in intact cells under conditions that would either induce or
reverse CP sensitization to establish a link between phosphorylation of a
particular protein and CP sensitization.
Effective start/end date14/02/9231/01/93