Synthesis Of Novel Retinoic Acid Derivatives And Their Effects On Melanoma Cells

Malignant melanoma is a common malignant tumor which is malignant transformation of skin or mucosal epithelial melanocytes,which has the characteristics of high drug resistance,easy recurrence and low survival rate.According to the World Health Organization,malignant melanoma is still one of the most aggressive human cancers,and the incidence of malignant melanoma has increased dramatically in the past few decades.The incidence of which in China has also doubled in recent years.The early stage of malignant melanoma is mainly surgical treatment,and drug therapy is mainly used for postoperative adjuvant treatment and advanced disseminated lesions which can not be operated.With the development of research,cytotoxic drugs,targeted drugs and immunotherapy have appeared successively in the treatment of malignant melanoma,and have achieved good therapeutic effects.In addition,with the progress of nanotechnology,nano-material-based targeted therapy and photod-ynamic therapy have also been achieved good therapeutic effectin recent years.However,the drug-resistance of malignant melanoma is still the biggest obstacle to the therapeutic effect.Therefore,it is important to study and overcome drug resistance in the treatment of malignant melanoma.Cancer stem cells(CSCs)are one of the many mechanisms of drug resistance in malignant tumors,including malignant melanoma.Cancer stem cells are a small group of cells with self-renewal and multi-directional differentiation in cancer,which are directly related to the occurrence,development,metastasis,recurrence and drug resistance of malignant tumors.Therefore,the number of cancer stem cells in the tumor determines the malignancy of the tumor.Because cancer stem cells are undifferentiated or poorly differentiated cells,it is a promising therapeutic strategy to induce differentiation of cancer stem cells,reduce their ability of proliferation,migration and drug resistance,and then use drugs to eliminate them.In the second chapter of this study,we used flow cytometry to isolate cancer stem cells from malignant melanoma A375cell line and investigated the effects of retinoic acid on it.The results showed that retinoic acid could significantly inhibit the proliferation of melanoma stem cells,block cell division,down-regulate the expression of Sox2 and Oct4,induce the differentiation of tumor stem cells,and reduce its tolerance to paclitaxel.It has certain guiding significance for the treatment of melanoma.However,we also found that retinoic acid had a poor inhibitory effect on ordinary melanoma cells other than melanoma stem cells.In addition,retinoic acid is insoluble in water,and the way of administration and inefficiency limit its clinical application.The basic structure of retinoic acid consists of three parts:the hydrophobic part composed of three methylated ethylene units,the intermediate chain of the conjugated four side chains and the hydrophilic end of the carboxyl group.Adding other groups to the carboxyl group of retinoic acid is a common way to synthesize retinoic acid derivatives,which do not change its main functional groups.Therefore,we hoped that by modifying retinoic acid molecules,its shortcomings of poor water solubility and poor cytotoxicity to ordinary cancer cells were overcome,and its role in inducing differentiation of cancer stem cells was retained.In the third chapter,we used all trans retinoic acid and ferroceny lmethanol as raw materials.Ferrocenyl group was added to its carboxyl end,which had excellent redox properties.Ferrocene was then oxidized by ferric chloride to form a new retinoic acid derivative with positive charge-FCRA~+.The product retained the functional groups of the retinoic acid molecule and greatly increased its water solubility.In addition,the product can consume a large number of reduced glutathione(GSH)in cancer cells,so it has a stronger anti-cancer effect than retinoic acid.In the fourth chapter of this study,through compared with retinoic acid,inhibitory effect on melanoma cells of FCRA~+was verified in vitro.The results showed that FCRA~+could inhibit proliferation and induce apoptosis of melanoma cells more strongly than retinoic acid.The mechanism was that FCRA~+depleted GSH in melanoma cells,resulting in the accumulation of reactive oxygen species(ROS)in the cells,and leading to apoptosis.In addition,FCRA~+had the same effect as retinoic acid on melanoma stem cells,which could induce their differentiation and increase their sensitivity to paclitaxel.Therefore,the experiment proved that FCRA~+retained the functional activity of retinoic acid,and had increased the anticancer and water-solubility than retinoic acid,which had a better application prospect than retinoic acid.However,further studies are still need in the effect of FCRA~+on other tumor cells,the effect of FCRA~+on melanoma or other malignant tumors in vivo,and the detailed mechanism in that,as well as the distribution,metabolism and biological safety in vivo.