3-hydroxy-4-prenyl-5-methoxystilbene-2-carboxylic-acid and Breast-Neoplasms

In the present study, we investigated the activity and modes of action of cajanin stilbene acid (CSA) and its derivatives in terms of cytotoxicity, gene expression profile, and transcription factor activity. XTT assays on MCF7 cells were performed upon treatment with CSA or derivatives. After the determination of IC50 values, gene expression profiling was performed with Agilent microarray experiments. Deregulated genes were determined with Chipster software, pathway and functional analyses were performed with Ingenuity pathway software. In order to identify the potential upstream regulators, MatInspector software was used to perform transcription factor binding motif search in the promoter regions of the deregulated genes. Molecular docking on MYC/MAX complex and reporter cell line experiments were performed to validate the MYC inhibitory activity of CSA and its derivatives. Two known MYC inhibitors: 10058-F4 and 10074-G5 were used as positive control. All compounds showed cytotoxicities in the micromolar range. Microarray analyses pointed to cell cycle, DNA damage, and DNA repair as mainly affected cellular functions. Promoter motif analysis of the deregulated genes further supported the microarray gene expression analysis results emphasizing the relevance of transcription factors regulating cell cycle and proliferation, with MYC as being the most pronounced one. Luciferase-based reporter cell line experiments and molecular docking studies yielded supportive results emphasizing the inhibitory activity of CSA and its derivatives on MYC. CSA and its derivatives are shown to be promising anticancer compounds with low toxicity. They inhibit MYC activity comparable to 10058-F4 and 10074-G5. Further studies are warranted to analyze the therapeutic applicability of these compounds in more detail.

Topics: Antineoplastic Agents; Breast Neoplasms; Diethylstilbestrol; Drug Screening Assays, Antitumor; Female; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Genes, myc; Humans; MCF-7 Cells; Molecular Docking Simulation; Oligonucleotide Array Sequence Analysis; Promoter Regions, Genetic; Salicylates; Stilbenes

Antiestrogenic therapy is a mainstay for estrogen receptor (ERα)-positive breast cancer. Due to the development of resistance to established antihormones such as tamoxifen, novel compounds are required. The low abundant cajanin stilbene acid (CSA) recently isolated by us from Pigeon Pea (Cajanus cajan) has structural similarities with estrogen. We analyzed the cytotoxic and anticancer activity of CSA in ERα-positive and -negative human breast cancer cells in vitro, in vivo and in silico. CSA exerts anticancer and antiestrogenic activities towards ERα-positive breast cancer, and it showed cytotoxicity towards tamoxifen-resistant MCF-7 cells, implying that CSA may be active against tamoxifen-resistant breast cancer cells. CSA showed low cytotoxicity in ERα-negative breast tumor cells as expected. Comparable cytotoxicity was observed towards p53 negative MCF-7 cells, implying that CSA is effective independent of the p53 status. Xenografted MCF-7 cells in nude mice were better inhibited by CSA than by cyclophosphamide. Testing of 8 primary cell cultures derived from human breast cancer biopsies showed that cell cultures from ER-positive tumors were more sensitive than from ER-negative ones. Dose-dependent decrease in ERα protein levels was observed upon CSA treatment. Synergistic effect with tamoxifen was observed in terms of increased p53 protein level. CSA affected pathways related to p53, cancer and cell proliferation. Gene promoter analyses supported the ERα regulation. CSA bound to the same site as 17β-estradiol and tamoxifen on ERα. In conclusion, CSA exerts its anticancer effects in ERα-positive breast cancer cells by binding and inhibiting ERα.

Topics: Adult; Animals; Antineoplastic Combined Chemotherapy Protocols; Breast Neoplasms; Cell Line, Tumor; Estrogen Antagonists; Estrogen Receptor alpha; Female; Gene Expression Regulation, Neoplastic; Humans; MCF-7 Cells; Mice, Nude; Middle Aged; Promoter Regions, Genetic; Receptors, Estrogen; Salicylates; Stilbenes; Tamoxifen; Xenograft Model Antitumor Assays