Anti-proliferative effect of retinoids and interferon-α-2a on vaginal cell lines derived from squamous intra-epithelial lesions

Abstract

A panel of retinoids (all-trans-, 13-cis-, 19-cis retinoic acid and acitretin), and interferon-α-2a was tested for the capacity to modulate the proliferation of UT-DEC-1 (HPV-33-positive) and UT-DEC-2 (HPV-16-positive) cell lines derived from vaginal intra-epithelial neoplasias (VAIN). At concentrations 10-6 to 10-8 M, all retinoids inhibited the growth of early-passage UT-DEC cell lines, but also of normal vaginal keratinocytes and fibroblasts. The inhibition was significantly reduced in late-passage UT-DEC cells. The effect on proliferation was essentially equal for all retinoids in high (1.8 mM)-Ca2+ medium, but decreased markedly in low (0.09 mM)-Ca2+ medium. Interferon-α-2a at 1000 IU/ml had an additive growth-inhibitory effect in the low- and in the high-Ca2+ medium. No consistent decrease in HPV E6-E7 mRNA levels could be associated either with retinoid or with interferon effect in either cell line. The expression of TGFβ1 and TGFβ2 mRNA increased 2- to 3-fold by 10-6 M 13-cis-RA treatment in early- and in late-passage cells of both cell lines. TGFβ1 at 0.1 to 1.0 ng/ml also inhibited the proliferation of both cell lines, and was more effective at early passage, but the inhibition was not dependent on calcium concentration. Neutralizing anti-TGFβ antibodies partially relieved the proliferation inhibition by 13-cis-RA. The results show that the calcium-associated regulation of growth by the tested retinoids was seen in normal vaginal cells and in early pre-neoplastic cells, but was significantly reduced in cells with higher-grade phenotype, while also suggesting that the loss of responsiveness to retinoids and TGFβ may play a role in the progression of squamous intra-epithelial neoplasia.