الفهرس 
Classical definition of epigeneticsOnly 14 pages are availabe for public view
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Abstract
Epigenetics is the study of heritable variations in gene expression that take place without altering the DNA sequence. chromatin remodeling, dysregulated histone modification patterns, aberrant production of micro-RNAs (miRNAs), and long non-coding RNAs are examples of epigenetic alterations (lncRNAs). Carcinogenesis is a multi-step operation caused by genetic changes that activate many signal transduction pathways, resulting in the gradual conversion of a healthy cell into a cancer cell. Malignant transformation is caused by either the loss of production or functional inactivation of genes that limit cell growth or by the overexpression or hyperactivation of genes that promote cell survival and proliferation. Chemotherapeutic agents induce tumor cells death; however they also damage normal cells particularly when applied in high doses. Medicinal agents have been found in nature; cancer targeted therapies, which have clinical implications for the fight against cancer as well as its treatment, are abundant in natural products. Nigella sativa is a Mediterranean-native, Pakistan, and India annual flowering plant that is also commonly known as black cumin. Thymoquinone (TQ), an active ingredient found in black seeds, is frequently used as a seasoning in medicine. It was also shown that TQ has antineoplastic effects via inhibiting cell proliferation, inducing apoptosis, cell cycle arrest, generating ROS, and inhibiting metastasis and angiogenesis, among other mechanisms. Black pepper, frequently labelled as the “king of spices”. The high amount of piperine in pepper gives it its characteristic pungency and biting flavour. It has been shown that piperine prevents a number of cancer cells from growing and surviving via triggering apoptotic signals and disrupt cell cycle progression. In this experiment, human breast cancer cell line MDA-MB-231 and human hepatocellular carcinoma cell line HepG2 were divided into nine groups. The groups are group I: Positive control group (cancer without treatment), group II: TQ treated cancer group, group III: piperine treated cancer group, group IV: Sorafenib treated cancer group, group V: TQ + Piperine in combination treated cancer group, group VI: TQ + Sorafenib in combination treated cancer group, group VII: piperine + Sorafenib in combination treated cancer group and group VIII: TQ + Piperine + Sorafenib in combination treated cancer group. For all cellular and molecular analysis, both HepG2 and MDA-MB-321 cells were treated with half of the predetermined IC50 value for each compound which was calculated by MTT assay as mentioned before. The final DMSO concentration used to treat the cells was 0.1%. Each therapy was carried out for 48 hours before the corresponding analysis. Each experiment was carried out in duplicate and at least three times independently. We measured cytotoxicity by MTT assay, cell cycle and apoptosis by flowcytometry, activities of antioxidant enzyme colorimetrically and relative gene expression of DNA methyltransferase (DNMT3B), histone deacetylase (HDAC3) and miRNA-29c by real-time PCR. We observed that, combinations of TQ, PIP with Sorafenib have significantly enhanced its antiproliferative and cytotoxic effects in HepG2 and MDA-MB321. In MDA-MB-231 cells, TQ and SOR single treatment caused the highest G2/M cell cycle arrest, while all SOR single treatment caused G2/M arrest in HepG2. Triple combination of TQ + PIP + Sorafenib caused the highest apoptosis and necrosis in MDA-MB-231 and HepG2, respectively. Sorafenib alone caused the highest superoxide dismutase and catalase activities in both cell lines and the lowest malondialdehyde levels in HepG2 cells, while TQ + PIP caused the lowest malondialdehyde levels in MDA-MB-231. Epigenetically, triple combination of TQ + PIP + sorafenib caused the lowest DNMT3B and HDAC3 expression in MDA-MB-231 and HepG2 cells, respectively, while single treatment with SOR and PIP caused the lowest DNMT3B and HDAC3 expression in HepG2 and MDA-MB-231 cells, respectively and PIP alone or combined with TQ caused the highest expression of the tumour suppressor miRNA-29c in HepG2 and MDA-MB-231, respectively. Finally, Molecular docking study showed that SOR with the highest binding affinity toward DNMT3B, HDAC3 and VEGFR-2, while TQ exhibited the lowest affinity. These results suggest that TQ and PIP might be used as a promising anti-cancer therapeutic agent in combination with Sorafenib specially it should be tested in apoptosis-resistant tumor.