Epigenetic modifications can affect the long-term gene expression without any change in nucleotide sequence of the DNA. Epigenetic processes intervene in the cell differentiation, chromatin structure, and activity of genes since the embryonic period. However, disorders in genes' epigenetic pattern can affect the mechanisms such as cell division, apoptosis, and response to the environmental stimuli which may lead to the incidence of different diseases and cancers. Since epigenetic changes may return to their natural state, they could be used as important targets in the treatment of cancer and similar malignancies. The aim of this review is to assess the epigenetic changes in normal and cancerous cells, the causative factors, and epigenetic therapies and treatments.

Curcumin, a lipid-soluble compound extracted from the plant Curcuma Longa, has been found to exert immunomodulatory effects via macrophages. However, most studies focus on the low bioavailability issue of curcumin by nano and microparticles, and thus the role of macrophages in the anticancer mechanism of curcumin has received little attention so far. We have previously shown the potential biocompatibility, biodegradability and anti-cancer effects of dendrosomal curcumin (DNC). In this study, twenty-seven BALB/c mice were equally divided into control as well as 40 and 80 mg/kg groups of DNC to investigate the involvement of macrophages in the antitumor effects of curcumin in a typical animal model of metastatic breast cancer. At the end of intervention, the tumor volume and weight were significantly reduced in DNC groups compared to control (P<0.05). Histopathological data showed the presence of macrophages in tumor and spleen tissues. Real-time PCR results showed that DNC increased the expression of STAT4 and IL-12 genes in tumor and spleen tissues in comparison with control (P<0.05), referring to the high levels of M1 macrophages. Furthermore treatment with DNC decreased STAT3, IL-10 and arginase I gene expression (P<0.05), indicating low levels of M2 macrophage. The results confirm the role of macrophages in the protective effects of dendrosomal curcumin against metastatic breast cancer in mice.

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A partial response or resistance to chemotherapeutic agents is considered as a main obstacle in treatment of patients with cancer, including breast cancer. Refining taxane-based treatment procedures using adjuvant or combination treatment is a novel strategy to increase the efficiency of chemotherapy. PPM1D is a molecule activated by reactive oxygen species. whose expression is reported to modulate the recruitment of DNA repair molecules. In this study we examined the impact of arsenic trioxide on efficacy of paclitaxel-induced apoptosis in paclitaxel-resistant MCF-7 cells. We also investigated the expression of PPM1D and TP53 genes in response to this combination treatment. Resistant cells were developed from the parent MCF-7 cell line by applying increasing concentrations of paclitaxel. MTT assays were applied to determine the rate of cell survival. DAPI staining using fluorescent microscopy was employed to study apoptotic bodies. Real-time RT-PCR analysis was also applied to determine PPM1D mRNA levels. Our results revealed that combination of arsenic trioxide and paclitaxel elevates the efficacy of the latter in induction of apoptosis in MCF-7/PAC resistant cells. Applying arsenic trioxide also caused significant decreases in PPM1D mRNA levels (p<0.05). Our findings suggest that arsenic trioxide increases paclitaxel-induced apoptosis by down regulation of PPM1D expression. PPM1D dependent signaling can be considered as a novel target to improve the efficacy of chemotherapeutic agents in resistant breast cancer cells.