Clonal growth inhibition as a bioassay for thymosin alpha1: inactivation of Talpha1 by trifluroacetic acid.

Thymosin alpha1 (Talpha1) is an immune response modifying peptide isolated from thymus tissue. The synthetic peptide has been evaluated in clinical trials as an adjuvant to cancer chemotherapy, an enhancer of vaccine potency, and an anti-viral for both hepatitis B and C. Among its multiple in vitro activities is the inhibition of the clonal growth of hepatitis B transfected hepatoblastoma cells.

Cloning of a novel EGFR-related peptide: a putative negative regulator of EGFR.

Although epidermal growth factor receptor (EGFR) plays a key role in regulating cell proliferation, differentiation, and transformation in many tissues, little is known about the factor(s) that may modulate its function. We have isolated a cDNA clone from the rat gastroduodenal mucosa whose full length revealed 1,958 bp that contained 227 bp of 5'-untranslated region (UTR) and an open-reading frame encoding 479 amino acids, followed by 290 bp of 3'-UTR. It showed ~85% nucleotide homology to the external domain of the rat EGFR.

TGFalpha is required for full expression of the transformed growth phenotype of NIH 3T3 cells overexpressing ornithine decarboxylase.

Ornithine decarboxylase (ODC) overexpressed from a heterologous promoter drives the tumorigenic transformation of NIH 3T3 cells and provides a model to investigate the underlying molecular mechanisms. These transformed cells, designated NODC cells, exhibit elevated levels of epidermal growth factor receptor (EGFR) tyrosine kinase (Tyr-k) activity relative to control transfected cells and inhibition of EGFR Tyr-k activation suppresses the transformed growth phenotype of these cells. Thus, ODC-induced transformation of NIH 3T3 cells appears to be mediated, at least in part, by enhanced signaling through the EGFR pathway.

Tryosine kinase and ornithine decarboxylase activation in children with Helicobactor pylori gastritis.

H. pylori infection has been considered a risk factor for the development of gastric malignancy. Ornithine decarboxylase and tyrosine kinases activities are increased in patients with colon or esophageal cancer.