The methylation induced by protein arginine methyltransferase 5 promotes tumorigenesis and progression of lung cancer

PRMT5 Inhibition Enhances Therapeutic Efficacy of Cisplatin via Mediating miR-29b-3p-Mcl-1 Expression in Lung Adenocarcinoma

Cisplatin is one of the front-line therapeutic agents used to treat cancers, while drug resistance is a great obstacle to anti-tumor efficiency. Protein arginine methyltransferase 5 (PRMT5) has been identified as a promoter of tumorigenesis, motility, and invasion. Inhibiting PRMT5 reduced hypoxia-induced carboplatin resistance in lung adenocarcinoma (LUAD). However, the specific relationship between PRMT5 and cisplatin (CDDP) warrants further investigation. Our research revealed that PRMT5 inhibitor C9 enhanced CDDP chemosensitivity by suppressing proliferation and promoting apoptosis in LUAD cells. Through examining pro-apoptotic proteins regulated by PRMT5, we identified that Mcl-1 played a significant role in PRMT5-mediated CDDP chemosensitivity. Furthermore, PRMT5 regulated Mcl-1 expression through mediating miR-29b-3p. In vivo, our research presented that C9 increased CDDP chemosensitivity in LUAD xenografts. All in all, our data raised an interesting possibility that epigenetic reprogramming was associated with chemosensitivity. PRMT5 inhibitor C9 improved CDDP effectiveness in LUAD cells by inhibiting Mcl-1 expression via miR-29b-3p, thereby modulating cellular proliferation and apoptosis.

DNA and protein methyltransferases inhibition by adenosine dialdehyde reduces the proliferation and migration of breast and lung cancer cells by downregulating autophagy

Protein and DNA methylation is involved in various biological functions such as signal transmission, DNA repair, and gene expression. Abnormal regulation of methyltransferases has been linked to multiple types of cancer, but its link to autophagy and carcinogenesis in breast and lung cancer is not fully understood. We utilized UALCAN, a web tool, to investigate breast and lung cancer database from The Cancer Genome Atlas. We found that 17 methyltransferases are upregulated in breast and/or lung cancer. We investigated the effect of methylation inhibition on two breast cancer cell lines (MDA-MB-231 and MCF-7) and two lung cancer cell lines (H292 and A549) by treating them with the indirect methyltransferase inhibitor adenosine dialdehyde (AdOx). We found that the migration ability of all cell lines was decreased, and the growth rate of MDA-MB-231, MCF-7 and H292 was also decreased after AdOx treatment. These results were correlated with an inhibition of the autophagy in MDA-MB-231, MCF-7 and H292 cell lines, since AdOx treatment induced a decreased expression of ATG7, a reduced ratio LC3-II/LC3-I and an increased p62 level. These findings suggest that inhibiting cells' methylation ability could be a potential target for breast and lung cancer treatment.

The Role of the PRMT5-SND1 Axis in Hepatocellular Carcinoma

Arginine methylation is an essential post-translational modification (PTM) deposited by protein arginine methyltransferases (PRMTs) and recognized by Tudor domain-containing proteins. Of the nine mammalian PRMTs, PRMT5 is the primary enzyme responsible for the deposition of symmetric arginine methylation marks in cells. The staphylococcal nuclease and Tudor domain-containing 1 (SND1) effector protein is a key reader of the marks deposited by PRMT5. Both PRMT5 and SND1 are broadly expressed and their deregulation is reported to be associated with a range of disease phenotypes, including cancer. Hepatocellular carcinoma (HCC) is an example of a cancer type that often displays elevated PRMT5 and SND1 levels, and there is evidence that hyperactivation of this axis is oncogenic. Importantly, this pathway can be tempered with small-molecule inhibitors that target PRMT5, offering a therapeutic node for cancer, such as HCC, that display high PRMT5–SND1 axis activity. Here we summarize the known activities of this writer–reader pair, with a focus on their biological roles in HCC. This will help establish a foundation for treating HCC with PRMT5 inhibitors and also identify potential biomarkers that could predict sensitivity to this type of therapy.

PRMT5 Promotes Aerobic Glycolysis and Invasion of Breast Cancer Cells by Regulating the LXRα/NF-κBp65 Pathway

Objective

To explore the effects of protein arginine methyltransferase 5 (PRMT5) on the biological function of breast cancer cells (BCCs) by regulating the liver X receptor α (LXRα)/NF-κBp65 pathway.

Methods

A total of 80 patients with breast cancer (BC) admitted to our hospital were collected, and 80 breast cancer tissue specimens and 80 corresponding tumor-adjacent tissue specimens were sampled from them for analysis. The reverse transcription-polymerase chain reaction (RT-PCR) was employed to determine the expression of PRMT5 mRNA in the sampled tissues, and the Western blot to determine the expression of LXRα and NF-κBp65 proteins in the tissues and cells. The patients were followed up to analyze their 3-year survival rate. Stable and transient overexpression vectors and inhibition vectors were constructed and transfected into BCCs. The cell counting kit-8 (CCK8), transwell, and flow cytometry were adopted to analyze the proliferation, invasion, and apoptosis of transfected cells, on which the effects of PRMT5 on LXRα and NF-κBp65 proteins were analyzed.

Results

PRMT5 was highly expressed in BC patients, and LXRα was lowly expressed in them, which had a high diagnostic value. Patients with high expression of PRMT5 showed a poor prognosis, and the expression of PRMT5 was related to the tumor size, pathological stage, differentiation, and metastatic in BC patients. Overexpressed PRMT5 enhanced the cell proliferation, invasion, and glycolysis abilities, weakened apoptosis ability, further lowered expression of LXRα and increased expression of NF-κBp65, while inhibited PRMT5 caused opposite results in those aspects. Up-regulating the expression of LXRα suppressed the proliferation, invasion, and aerobic glycolysis of BCCs and promoted their apoptosis, while inhibiting it posed opposite effects. The rescue experiment revealed that down-regulating the expression of PRMT5 could counteract the promotion of down-regulation of LXRα on proliferation, invasion and glycolysis of BCCs, and the nude mouse tumorigenesis test revealed that PRMT5 induced tumor on nude mice by mediating LXRα/NF-κBp65.

Conclusion

Inhibition of the PRMT5 expression can accelerate apoptosis of BCCs and weaken their proliferation, invasion, and aerobic glycolysis through the LXRα/NF-κBp65 pathway.