• Clawson, Gary (PI)

Project: Research project

Project Details


Although chemical carcinogens produce cancer through diverse mechanisms,
there are nevertheless commonalities of carcinogen action. These include
nuclear enlargement and alterations in RNA transport and nuclear scaffold
(NS) NTPase, which controls the nucleocytoplasmic transport process. The
NS NTPase is derived from lamins A/C by a novel Ca2+-regulated serine
protease which appears to represent a unique multicatalytic protease
complex (MPC) associated with the NS. Alterations in this NS protease
appear to underlie the NTPase/RNA transport alterations of carcinogenesis,
and its chymotrypsin-like activity correlates with anticarcinogenic
activity of various protease inhibitors (ie, Bowman-Birk). A potent
peptide-chloromethylketone inhibitor (AAPFcmk) was identified, with a
K(i)=56 nM, which preferentially inhibited growth of transformed
hepatocyte cell lines. Further, AAPFcmk blocked chemical transformation
of fibroblasts in vitro even at femtomolar concentrations, selectively
affecting the nuclear/NS fractions. We hypothesize that the NS protease
may be important in transformation, and that its inhibition may block
secondary increases in NS NTPase, thwarting alterations in RNA transport.
We have obtained amino acid sequences from components of the NS protease,
and using RT/PCR amplifications with serine protease primers have
identified an expressed mRNA with homology to a hamster Ca2+-regulated
serine protease. Using a similar strategy, we have also obtained a number
of novel putative MPC components. This proposal is designed to define the
role of the NS protease in carcinogenesis. Specifically, we propose to l)
clone and sequence the novel NS serine protease; 2) Determine the nature
of the inhibition of cell growth in transformed hepatocyte cell lines; 3)
Define the relationship between alterations in NS protease expression and
transformation; and 4) Examine whether specific inhibition of the NS
protease, using antisense oligonucleotides and targeted ribozymes, blocks
transformation of fibroblasts, or blocks growth of transformed hepatocyte
cell lines.
Effective start/end date4/1/876/30/99


  • National Cancer Institute
  • National Cancer Institute
  • National Cancer Institute
  • National Cancer Institute
  • National Cancer Institute


Explore the research topics touched on by this project. These labels are generated based on the underlying awards/grants. Together they form a unique fingerprint.