Inhibition of G9a promoted 5-fluorouracil (5-FU) induced gastric cancer cell apoptosisviaROS/JNK signaling pathwayin vitroandin vivo

5-Fluorouracil dose escalation generated desensitized colorectal cancer cells with reduced expression of protein methyltransferases and no epithelial-to-mesenchymal transition potential

Background

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers. In many cases, the poor prognosis of advanced CRC is associated with resistance to treatment with chemotherapeutic drugs such as 5-Fluorouracil (5-FU). The epithelial-to-mesenchymal transition (EMT) and dysregulation in protein methylation are two mechanisms associated with chemoresistance in many cancers. This study looked into the effect of 5-FU dose escalation on EMT and protein methylation in CRC.

Materials and Methods

HCT-116, Caco-2, and DLD-1 CRC cell lines were exposed to dose escalation treatment of 5-FU. The motility and invasive potentials of the cells before and after treatment with 5-FU were investigated through wound healing and invasion assays. This was followed by a Western blot which analyzed the protein expressions of the epithelial marker E-cadherin, mesenchymal marker vimentin, and the EMT transcription factor (EMT-TF), the snail family transcriptional repressor 1 (Snail) in the parental and desensitized cells. Western blotting was also conducted to study the protein expressions of the protein methyltransferases (PMTs), Euchromatic histone lysine methyltransferase 2 (EHMT2/G9A), protein arginine methyltransferase (PRMT5), and SET domain containing 7/9 (SETD7/9) along with the global lysine and arginine methylation profiles.

Results

The dose escalation method generated 5-FU desensitized CRC cells with distinct morphological features and increased tolerance to high doses of 5-FU. The 5-FU desensitized cells experienced a decrease in migration and invasion when compared to the parental cells. This was reflected in the observed reduction in E-cadherin, vimentin, and Snail in the desensitized cell lines. Additionally, the protein expressions of EHMT2/G9A, PRMT5, and SETD7/9 also decreased in the desensitized cells and global protein lysine and arginine methylation became dysregulated with 5-FU treatment.

Conclusion

This study showed that continuous, dose-escalation treatment of 5-FU in CRC cells generated 5-FU desensitized cancer cells that seemed to be less aggressive than parental cells.

Molecular and functional anticancer effects of GLP/G9a inhibition by UNC0646 in MeWo melanoma cells

In recent years, histone methyltransferases (HMTs) have emerged as important therapeutic targets in cancer due to their oncogenic role. Herein, we used the GLP/G9a inhibitor UNC0646 to assess whether the inhibition of such HMTs could induce cell death in MeWo melanoma cells. Furthermore, we investigated the cellular and molecular mechanisms involved in the observed cell death events. Finally, we performed a functional genomics analysis of 480 melanoma samples to characterize G9a/GLP involvement in melanoma. Interestingly, after UNC0646 treatment, MeWo cells underwent apoptosis, followed by loss of mitochondrial membrane potential and the generation of reactive oxygen species (ROS). Furthermore, MeWo cells treated with UNC0646 showed cell cycle arrest and inhibition of proliferation. At the molecular level, UNC0646 treatment increased the transcriptional levels of CDK1 and BAX, and decreased BCL-2 mRNA levels. Finally, we performed a functional enrichment analysis, which demonstrated that dozens of biological pathways were enriched in melanoma samples according to GLP and G9a expression, including apoptosis and necrosis. Taken together, our data show that inhibition of GLP/G9a using UNC0646 exerts anticancer effects on melanoma cells by controlling their proliferation and inducing apoptosis.

Targeting H3K9 methyltransferase G9a and its related molecule GLP as a potential therapeutic strategy for cancer

H3K9 methyltransferase (G9a) and its relevant molecule GLP are the SET domain proteins that specifically add mono, di and trimethyl groups on to the histone H3K9, which lead to the transcriptional inactivation of chromatin and reduce the expression of cancer suppressor genes, which trigger growth and progress of several cancer types. Various studies have demonstrated that overexpression of H3K9 methyltransferase G9a and GLP in different kinds of tumors, like lung, breast, bladder, colon, cervical, gastric, skin cancers, hepatocellular carcinoma and hematological malignancies. Several G9a and GLP inhibitors such as BIX-01294, UNC0642, A-366 and DCG066 were developed to combat various cancers; however, there is a need for more effective and less toxic compounds. The current molecular docking study suggested that the selected new compounds such as ninhydrin, naphthoquinone, cysteamine and disulfide cysteamine could be suitable molecules as a G9a and GLP inhibitors. Furthermore, detailed cell based and preclinical animal studies are required to confirm their properties. In the current review, we discussed the role of G9a and GLP mediated epigenetic regulation in the cancers. A thorough literature review was done related to G9a and GLP. The databases used extensively for retrieval of information were PubMed, Medline, Scopus and Science-direct. Further, molecular docking was performed using Maestro Schrodinger version 9.2 software to investigate the binding profile of compounds with Human G9a HMT (PDB ID: 3FPD, 3RJW) and Human GLP MT (PDB ID: 6MBO, 6MBP).

Epigenetic Mechanisms in Gastric Cancer: Potential New Therapeutic Opportunities

Gastric cancer (GC) is one of the deadliest malignancies worldwide. Complex disease heterogeneity, late diagnosis, and suboptimal therapies result in the poor prognosis of patients. Besides genetic alterations and environmental factors, it has been demonstrated that alterations of the epigenetic machinery guide cancer onset and progression, representing a hallmark of gastric malignancies. Moreover, epigenetic mechanisms undergo an intricate crosstalk, and distinct epigenomic profiles can be shaped under different microenvironmental contexts. In this scenario, targeting epigenetic mechanisms could be an interesting therapeutic strategy to overcome gastric cancer heterogeneity, and the efforts conducted to date are delivering promising results. In this review, we summarize the key epigenetic events involved in gastric cancer development. We conclude with a discussion of new promising epigenetic strategies for gastric cancer treatment.

Cocrystallization of 5-fluorouracil and l-phenylalanine: the first zwitterionic cocrystal of 5-fluorouracil with amino acid exhibiting perfect in vitro/vivo pharmaceutical properties

The first zwitterionic cocrystal of 5-fluorouracil with amino acid has been prepared and its structure and in vitro/vivo properties have been systematically studied.