Thymosin alpha 1 does not promote growth or oncogenic transformation.
Thymosin alpha 1 (T alpha 1) is an immune modulatory peptide which has been evaluated in a variety of clinical trials. Although no in vivo adverse effects, including enhancement of tumor growth, have been noted, in vitro studies suggesting a role for T alpha 1 in cell growth have been reported. The studies presented in this report evaluated both exogenously added T alpha 1 and endogenously expressed T alpha 1 as factors which could either promote growth of tumor cells or induce transformation. No effect of exogenous T alpha 1 on cell growth was found. NIH-3T3 cells transfected with cDNA for the precursor ProThymosin alpha (Pro T alpha) expressed elevated levels of authentic T alpha 1 but did not demonstrate either enhanced proliferation in liquid culture or transformation as defined by the loss of contact inhibition or anchorage independent growth in soft agar. Thus these studies argue against the hypothesis that T alpha 1 is either an intracellular or extracellular growth promoter.
Naylor
P H
PH
Department of Internal Medicine, Wayne State University, School of Medicine, Detroit, MI 48201, USA.
Smith
M R
MR
Mutchnick
M G
MG
Naylor
C W
CW
Dosescu
J
J
Skunca
M
M
Moshier
J A
JA
D016475:3T3 Cells; D000230:Adenocarcinoma / Q000473:pathology; D000818:Animals; D001943:Breast Neoplasms / Q000473:pathology; D002430:Cecal Neoplasms / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000473:pathology; D006133:Growth Substances / Q000494:pharmacology*; D007078:Ileal Neoplasms / Q000473:pathology; D051379:Mice; D011498:Protein Precursors / Q000494:pharmacology*; D013947:Thymosin / Q000031:analogs & derivatives* / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D006133:Growth Substances; D011498:Protein Precursors; C040782:prothymosin alpha; D013947:Thymosin