Binding and growth-stimulation of cervical cancer cell lines by prolactin

Two cervical cancer cell lines CC7-T and Si-Ha were employed to observe the relationship between cervical cancer and prolactin. By immunocytochemical and indirect immunofluorescent assays using two prolactin monoclonal antibodies PRL-149 and PRL-151, both cell lines with added prolactin (10 ng/mL) were noted to be positive for PRL-151, but negative for PRL-149. The control cell lines from ovarian cancer and the myeloma lines were both stained negative. By using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, it was noted that CC7-T and Si-Ha grew better in the presence of various added concentrations of prolactin, ranging from 0.1 to 1,000 ng/mL, suggesting that prolactin may enhance the growth of cervical cancer. The degree of stimulation appears to depend on cell differentiation. However, prolactin levels in the cultured supernatant were undetectable by the enzyme immunoassay (EIA) method. We postulate that prolactin can bind and stimulate the growth of some cervical cancer cell lines, probably through the prolactin receptor rather than by autocrine regulation.