ABSTRACT
BACKGROUND: Retinoids are important agents for the treatment of cutaneous T-cell lymphomas (CTCL). But side effects and drug resistance caused by activation of RAR/RXR limited their clinical application. Therefore, it is urgent to develop new agents to fight against CTCL. ECPIRM, a 13-cis retinoic acid derivative, was reported that it inhibited proliferation and induced apoptosis of SCL-1 cells. OBJECTIVE: The aim of this study was to evaluate the biological activities and mechanisms of ECPIEM. METHODS: The effect of ECPIRM on cell proliferation was determined by MTT assay and Trypan blue exclusion assay while FACS analysis was used to detect changes in cell cycle and apoptosis in HUT78 cells. The influence of ECPIRM on RAR/RXR and JAK/STAT signaling was evaluated by western blot analysis. RESULTS: ECPIRM, better than other agents (all-trans retinoic acid,13-cis-retinoic acid or bexarotene), inhibited proliferation and induced apoptosis significantly in HUT78 cells, but with little cytotoxicity on normal lymphocytes. Then ECPIRM induced G0/G1 phase arrest by decreasing the expression of cyclinD1, cyclinE, CDK2 and CDK4 while increasing p21. Furthermore, the unaffected expression of RAR and RXR members suggested that ECPIRM acted independently of RAR/RXR pathway in HUT78 cells. But decreased phosphorylation of JAK1, STAT3, STAT5 and downregulated Bcl-xL, Cyclin D1 and c-Myc indicated that ECPIRM inhibited the activation of JAK/STAT signaling. CONCLUSION: ECPIRM inhibited proliferation, induced apoptosis and G0/G1 phase arrest in HUT78 cells through inhibiting JAK/STAT pathway but not RAR/RXR pathway, which presented ECPIRM as a promising candidate for the treatment of CTCL patients.
Subject(s)
Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Isotretinoin/pharmacology , Lymphoma, T-Cell, Cutaneous/drug therapy , Signal Transduction/drug effects , Skin Neoplasms/drug therapy , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Cell Proliferation/drug effects , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , Humans , Isotretinoin/chemical synthesis , Isotretinoin/chemistry , Janus Kinase 1/antagonists & inhibitors , Janus Kinase 1/metabolism , Janus Kinase 3/antagonists & inhibitors , Janus Kinase 3/metabolism , Lymphoma, T-Cell, Cutaneous/metabolism , Lymphoma, T-Cell, Cutaneous/pathology , Molecular Structure , STAT3 Transcription Factor/antagonists & inhibitors , STAT3 Transcription Factor/metabolism , STAT5 Transcription Factor/antagonists & inhibitors , STAT5 Transcription Factor/metabolism , Skin Neoplasms/metabolism , Skin Neoplasms/pathology , Structure-Activity RelationshipABSTRACT
Cutaneous squamous cell carcinoma (CSCC) is one of the most common cancers worldwide, requiring effective therapeutic interventions. Retinoids are important chemopreventive and therapeutic agents for a variety of human cancers including CSCC. In this study we synthesized a novel retinoic derivative N-(4-ethoxycarbonylphenyl) isoretinamide (ECPIRM) and evaluated its biological activities and possible mechanisms in human cutaneous squamous cell lines. ECPIRM had better inhibitory effect on the proliferation of squamous carcinoma cells SCL-1 and colo-16, compared with All-trans retinoic acid and 13-cis retinoic acid. ECPIRM had less toxicity to normal keratinocyte cell line HaCaT. Mechanistically, ECPIRM induced G1 cell cycle arrest in SCL-1 cells, via the downregulation of CDK2, CDK4, cycling D1 and cyclin E expression and upregulation of p21. In addition, these effects were at least partially due to the inhibition of JNK/ ERK-AP-1 signaling pathway by ECPIRM. Importantly, these effects of ECPIRM are independent of the classical retinoid receptor pathway, suggesting that the novel compound will have less side-effects in chemotherapy. These findings demonstrate that ECPIRM is a potential inhibitor of MPAK-AP-1 pathway, and is a potential therapeutic agent against CSCC.
