# ROLES OF MICROFILAMENT PROTEINS AND PLASTIN IN NEOPLASIA

> **NIH NIH R01** · CALIFORNIA INSTITUTE FOR MEDICAL RES · 1990 · $176,113

## Abstract

We are examining the relationship of beta-actin gene mutations to abnormal
cytoarchitecture, elevated growth potential, and neoplastic transformation
of human fibroblasts.  This is being accomplished in the following steps:
(1)\cloned genes for mutant and wildtype beta-actins have been isolated
from gene libraries of HUT-14 and HUT-14T cells; these actin genes have
been selected by recombination of the actin gene clone in lambda DNA with a
specially constructed plasmid PiVX containing a sub-cloned portion of
beta-actin cDNA homologous to the 3' untranslated region of the gene;
(2)\mutant and wildtype genes were distinguished by DNA sequencing and
restriction site polymorphisms at codons 36, 83, and 244; we have
established that each of these mutations occurred in separate sequential
steps during derivation of the highly tumorigenic cell line HUT-14T from a
diploid human fibroblast culture; (3) each of these mutant actin genes and
additional mutant actin genes have been inserted into a PSV-Z neoplasmid
and incorporated into normal human and rodent fibroblasts via gene
transfer; (4) after gene transfer these exogenous actin genes are
abundantly expressed such that often the exogenous mutant actin protein is
the most abundant cellular protein; (5) upon incorporation and expression
of mutant beta-actin genes in diploid human fibroblasts profound
morphologic transformation occurs;  and (6)\cultures treated with mutant
actin genes are being assessed for alterations in cytoarchitecture and
transformation by monitoring mutant beta-actin synthesis, escape from
senescence, focus formation, anchorage independence, aneuploidy, protein
profiles in two-dimensional gels, protease expression, and tumorigenesis in
athymic mice.  This approach will ultimately test the involvement of actin
mutations in abnormal cytoskeletal structure and function and expose their
relationship to neoplastic transformation and tumorigenicity. In the course
of this study we discovered that normal rodent fibroblasts synthesize an
abundant alpha-actin isoform not found in normal human fibroblasts.  This
alpha-actin is dramatically downregulated following transformation of
rodent cells in all instances tested thus far.  We are attempting to clone
a cDNA for this rodent cell transformation-sensitive actin so that we can
identify the actin isoform and examine its role in rodent cell
transformation.  (L)

## Key facts

- **NIH application ID:** 3172553
- **Project number:** 5R01CA034763-07
- **Recipient organization:** CALIFORNIA INSTITUTE FOR MEDICAL RES
- **SAM.gov UEI:** C153KXVAT4L5
- **Principal Investigator:** JOHN C LEAVITT
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1990
- **Award amount:** $176,113
- **Award type:** 5
- **Project period:** 1988-03-01 → 1991-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3172553

## Citation

> US National Institutes of Health, RePORTER application 3172553, ROLES OF MICROFILAMENT PROTEINS AND PLASTIN IN NEOPLASIA (5R01CA034763-07). Retrieved via MORVS 2026-10-24 from https://api.morvs.ai/grant/nih/3172553. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*