cAMP and PMA enhance the effects of IGF-I in the proliferation of endometrial adenocarcinoma cell line HEC-1-A by acting at the G1 phase of the cell cycle.
The present study was undertaken to determine whether endometrial cancer cell line HEC-1-A differ from nontransformed cells, in that the cAMP and protein kinase C pathways may enhance IGF-I effects in mitogenesis by acting at the G1 phase of the cell cycle instead of G0. Immunofluorescence staining of HEC-1-A cells using the proliferating cell nuclear antigen (PCNA) monoclonal antibody and flow cytometric analysis determined that HEC-1-A cells do not enter the G0 phase of the cell cycle when incubated in a serum-free medium. Approximately 51% of the cells were in G1, 12% were in S and 37% in G2 phase of the cell cycle prior to treatment. Forskolin and phorbol-12-myristate 13-acetate (PMA) were used to stimulate cAMP production and protein kinase C activity, respectively. IGF-I, forskolin and PMA each increased (P < 0.01) [3H]-thymidine incorporation in a dose and time dependent manner. The interaction of forskolin and PMA with IGF-I was then determined. Cells preincubated with forskolin or PMA followed by incubation with IFG-I incorporated significantly more (P < 0.01) [3H]-thymidine into DNA than controls or any treatment alone. It is concluded that forskolin and, to a lesser extent, PMA exert their effect at the G1 phase of the cycle to enhance IGF-I effects in cell proliferation.
Talavera
F
F
Department of Obstetrics and Gynecology, University of Michigan Medical Center, Ann Arbor 48109-0278, USA.
Bergman
C
C
Pearl
M L
ML
Connor
P
P
Roberts
J A
JA
Menon
K M
KM
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000230:Adenocarcinoma / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D016895:Culture Media, Serum-Free; D000242:Cyclic AMP / Q000494:pharmacology*; D004075:Diglycerides / Q000494:pharmacology; D004347:Drug Interactions; D016889:Endometrial Neoplasms / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D016193:G1 Phase / Q000187:drug effects; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007399:Interphase / Q000187:drug effects*; D010703:Phorbol Esters / Q000494:pharmacology*; D018809:Proliferating Cell Nuclear Antigen / Q000302:isolation & purification; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D015398:Signal Transduction; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured
D016895:Culture Media, Serum-Free; D004075:Diglycerides; D010703:Phorbol Esters; D018809:Proliferating Cell Nuclear Antigen; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D007334:Insulin-Like Growth Factor I; C038237:1-oleoyl-2-acetylglycerol; D000242:Cyclic AMP; D013936:Thymidine