Nuclear PRMT1 expression is associated with poor prognosis and chemosensitivity in gastric cancer patients

BACKGROUND

Metastatic and refractory gastric cancer (GC) are associated with a poor prognosis; therefore, the identification of prognostic factors and chemosensitivity markers is extremely important. Protein arginine methyltransferase 1 (PRMT1) may play a role in chemosensitivity/apoptosis induction via activation of the tumor suppressor forkhead box O1 (FOXO1). The purpose of this study was to clarify the expression of and relationship between PRMT1 and FOXO1 to evaluate the applicability of PRMT1 as a prognostic marker and a therapeutic tool in GC.

METHODS

We investigated the clinical and functional significance of PRMT1 and FOXO1 in 195 clinical GC samples using immunohistochemistry. We performed suppression analysis of PRMT1 using small interfering RNA to determine the biological roles of PRMT1 in chemosensitivity.

RESULTS

PRMT1 and FOXO1 in GC samples were predominantly expressed in the nucleus. Patients with lower PRMT1 expression (n = 131) had suppressed nuclear accumulation of FOXO1, higher recurrence after adjuvant chemotherapy, and poorer prognosis than those with higher PRMT1 expression (n = 64). PRMT1 downregulation in GC cells by RNA interference inhibited cisplatin and 5-fluorouracil sensitivity. The expression of phosphorylated FOXO1 and phosphorylated BCL-2 antagonist of cell death was upregulated in PRMT1 small interfering RNA groups.

CONCLUSION

Our data suggest that the evaluation of PRMT1 expression in GC is a useful predictor of poor prognosis and recurrence after adjuvant chemotherapy. Moreover, these data suggest that PRMT1 is a promising therapeutic tool for overcoming refractory GC.

Introduction to the multi-author review on methylation in cellular physiology

Protein post-translational modifications (PTMs) have long been a topic of intensive investigation. Covalent additions to the 20 genetically encoded amino acids can alter protein interactions and can even change enzymatic function. In eukarya, PTMs can amplify both the complexity and functional paradigms of the cellular environment. Therefore, PTMs have been of substantial research interest, both for understanding fundamental mechanisms and to provide insight into drug design. Indeed, targeting proteins involved in writing, reading, and erasing PTMs important for human pathologies are some of the most fruitful avenues of drug discovery. In this multi-author review, we explore exciting new work on lysine and arginine methylation, molecular and structural understanding of some of the lysine and arginine methyltransferases (KMTs and PRMTs, respectively), novel insights into nucleic acid methylation, and how the enzymes responsible for writing these PTMs and readers responsible for recognizing these PTMs could be drugged. Here, we introduce the background and the topics covered in this issue.

Chemogenomic study of gemcitabine using Saccharomyces cerevisiae as model cell-molecular insights about chemoresistance

Gemcitabine (GEM) is the drug used as first line to treat pancreatic cancer, one of the most devastating human tumors. This peculiar type of tumor develops resistance to several drugs, including GEM, due to its desmoplastic reaction and other features. The GEM chemoresistance has been investigated at molecular level aiming to find a pathway whose inhibition or activation should overcome it. Through next-generation sequencing was performed a chemogenomic assay of GEM using Saccharomyces cerevisiae as model cell and the results showed that more than 40% of genes related to GEM response in yeast possess unknown or dubious function. We choose two yeast mutants to individually validate the fitness defect results observed by chemogenomic assay, Δhmt1 and Δcsi1, and it was found that in addition to some already described pathways involved in GEM resistance, cells deficient in deneddylation enzyme Cop9 Signalosome Interactor 1 (Csi1p) presented a high sensitivity to GEM. This was confirmed by individual growth analyses of Δcsi1 cells exposed to GEM, and this phenotype was reverted with CSI1 complementation gene. Csi1p is a well-characterized homolog equivalent to human Csn6 subunit of COP9 signalosome (CSN) involved in deneddylation process. We highlighted too that epigenetic alterations, such as methylation mediated by protein arginine methyltransferase 1, play an important role in regulating gemcitabine treatment resistance. Our results point out new unexplored molecular pathways that can be used to overcome GEM resistance: the inhibition of CSN and the arginine methyltransferase activities.

Arginine methylation and respiratory disease

Arginine methylation, a vital post-translational modification, plays a pivotal role in numerous cellular functions such as signal transduction, DNA damage response and repair, regulation of gene transcription, mRNA splicing, and protein interactions. Central to this modification is the role of protein arginine methyltransferases (PRMTs), which have been increasingly recognized for their involvement in the pathogenesis of various respiratory diseases. This review begins with an exploration of the biochemical underpinnings of arginine methylation, shedding light on the intricate molecular regulatory mechanisms governed by PRMTs. It then delves into the impact of arginine methylation and the dysregulation of arginine methyltransferases in diverse pulmonary disorders. Concluding with a focus on the therapeutic potential and recent advancements in PRMT inhibitors, this article aims to offer novel perspectives and therapeutic avenues for the management and treatment of respiratory diseases.

Structure-based discovery of potent CARM1 inhibitors for colorectal cancer therapy

Coactivator-associated arginine methyltransferase 1 (CARM1) plays an important role in cell proliferation and gene expression, and is highly expressed in a variety of tumor tissues. Guided by our previous reported structure of DCPR049_12, we focused on designing and evaluating selective CARM1 inhibitors, resulting in the identification of compound 11f as a promising lead candidate. Compound 11f displayed potent inhibition of CARM1 (IC50 = 9 nM). Comprehensive evaluations, including in vitro metabolic stability assessments, molecular modelling, cellular studies, and in vivo anti-tumor studies, confirmed that it induced cancer cell apoptosis and specifically inhibited CARM1's methylation function. Notably, compound 11f displayed significant anti-proliferative effects on colorectal cancer cell lines, showcasing its potential for targeted therapies against CARM1-related diseases. This study provides valuable insights for the future development of specific and effective CARM1 inhibitors.