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Ethyl acetate fraction of Radix rubiae inhibits cell growth and promotes terminal differentiation in cultured human keratinocytes

Authors Zhou, Lin-Li; Lin, Zhi-Xiu; Fung, Kwok-Pui; Che, Chun-Tao; Zhao, Ming; Cheng, Christopher H. K.; Zuo, Zhong

Journal JOURNAL OF ETHNOPHARMACOLOGY , FEB 10 2021,:266

DOI 10.1016/j.jep.2020.113404 PubMed 32976970

Abstract Ethnopharmacological relevance: In Chinese medicine practice, Radix rubiae, the dry root of Rubia cordifolia L is commonly used for the treatment of psoriasis.Aim of the study: Psoriasis is a chronic inflammatory skin disorder characterized by hyperproliferation and aberrant differentiation of epidermal keratinocytes. Our previous studies identified Radix rubiae to have potent antiproliferative action on cultured HaCaT keratinocytes and to induce keratinocyte differentiation in mouse tail model. The present study aimed to investigate whether Radix rubiae could also induce terminal differentiation in cultured human keratinocytes.Methods and results: The cornified envelope (CE) formation assay showed that ethyl acetate (EA) fraction of Radix rubiae significantly accentuated the CE formation, a well-recognized marker of terminal differentiation, in cultured HEM and HaCaT cells in a dose and time dependent manner. Western blot analyses demonstrated that EA fraction of Radix rubiae at a concentration of 3.2 mu g/ml significantly increased transglutaminase type 1 and involucrin expression in both HEM and HaCaT keratinocytes after 96 h treatment, a response similar to that of Ca2+ positive control. Moreover, the expression level of cytokeratin 5/14, which is specifically related to cell proliferation, was significantly downregulated while terminal differentiation markers cytokeratin 1/10 were markedly increased by Radix rubiae treatment in both HEK and HaCaT cells.Conclusion: The present experimental findings unequivocally confirmed the keratinocyte terminal differentiation promoting capacity of Radix rubiae, and strongly suggest that Radix rubiae is a promising antipsoriatic agent warranting further clinical development for psoriasis treatment. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

Species covered 茜草 Rubia cordifolia