Cell death induced by N‐(4‐hydroxyphenyl)retinamide in human epidermal keratinocytes is modulated by TGF‐β and diminishes during the progression of squamous cell carcinoma

Abstract

It has been demonstrated that the chemopreventive agent N-(4-hydroxyphenyl)retinamide (4-HPR) induces apoptotic cell death, but recent data has suggested that late stage/recurrent tumours lose their response to 4-HPR-induced cell death by mechanisms that are unknown. Our study investigated the ability of 4-HPR to induce cell death in keratinocyte cell lines that represent different stages of carcinogenesis and the role of TGF-b signalling in the induction of cell death by 4-HPR. We show that treatment of the immortalised keratinocyte cell line HaCaT with 10 -5 M 4-HPR induced cell death by apoptosis and caused an accumulation of cells in the G0/G1 phase of the cell cycle. Using a genetically related series of human skin keratinocytes derived from HaCaT that reflect tumour progression and metastasis in vivo, we demonstrate that 4-HPR-induced cell death and apoptosis is attenuated in the more aggressive tumour cell lines but that a reduced level of response is retained. Response to TGF-b-induced growth inhibition was also reduced in the more aggressive cell lines. Treatment of HaCaT cells with 4-HPR induced TGF-b2 expression and an increase in the amount of active TGF-b in the culture medium. The inhibition of TGF-b signalling attenuated 4-HPR-induced apoptosis and both TGF-b1 and TGF-b2 potentiated 4-HPR-induced apoptosis and enhanced 4-HPR-induced growth inhibition. Our results demonstrate that loss of response to 4-HPR correlates with a loss of response to the growth inhibitory effects of TGF-b and that adjuvant therapies that upregulate TGF-b may enhance the chemopreventive effects of 4-HPR. ' 2006 Wiley-Liss, Inc.

TGF-beta1 causes epithelial-mesenchymal transition in HaCaT derivatives, but induces expression of COX-2 and migration only in benign, not in malignant keratinocytes

“…Another study showed that tumor progression of these derivatives was associated with progressive abrogation of TGF-b1 and EGF growth control [33]. Contradicting these results and the results by Davies et al [20], we show here that TGF-b1 is able to cause proliferation arrest also in metastatic RT3 cells. These cells seem to hyperproliferate, as shown by the cell proliferation assay, but given their metastatic potential the morphology is not fibroblastoid spindle-shape that is normally associated with invasive cells, and curiously TGF-b1 did not cause morphological change in RT3 cells, but did change the morphology of HC, A5 and II-4 cells.…”

“…As expected, TGF-b1 inhibited cell proliferation of benign HC and A5 HaCaT clones. It also inhibited the proliferation of malignant II-4 and RT3, which contradicts previous results [20] (P < 0.05 compared to control in all HaCaT derivatives) (Fig. 1A).…”

Characterisation of the cancer-associated glucocorticoid system: key role of 11β-hydroxysteroid dehydrogenase type 2

“…Following subcutaneous transplantation to athymic mice, HaCaT cells are non-tumourigenic, I-7 cells form non-invasive epidermoid cysts, II-3 cells form primary SCCs with minimal metastatic dissemination and RT-3 cells, the most aggressive cell type, form large SCCs at the site of inoculation and have widespread metastatic dissemination (Fusening and Boukamp, 1998). The cells are widely used as a model of epidermal cancer progression ( Davies et al , 2006 ) and were last authenticated prior to commencing the experiments in 2012 with mRNA microarrays. The oral SCC cell strain (H357) underwent full genome sequencing in 2016 whereas the skin SCC cell line A431 was purchased from Sigma-Aldrich.…”

Dihydroorotate dehydrogenase is required for N-(4-hydroxyphenyl)retinamide-induced reactive oxygen species production and apoptosis

“…5 to 10 μM) induced apoptosis in skin [5, 16, 17] and prostate [4, 18-20] epithelial cells. In fact, we have reported that 12- to 24-h exposures to 5 μM 4HPR were quite effective in triggering conspicuous (i.e., occurring in ~50% or more of the treatment populations) cell death in transformed skin [17] and prostate [4] epithelial cells.…”