The enzyme L-isoaspartyl (D-aspartyl) methyltransferase promotes migration and invasion in human U-87 MG and U-251 MG glioblastoma cell lines

PCMT1 is a potential target related to tumor progression and immune infiltration in liver cancer

BACKGROUND

Liver cancer is a prevalent and deadly form of cancer with high incidence and mortality rates. The PCMT1 protein has been linked to cell anti-apoptosis and tumor metastasis, but its significance in liver hepatocellular carcinoma (LIHC) remains largely unexplored.

METHODS

We conducted a pan-cancer analysis to examine the expression differences of PCMT1. Kaplan-Meier curves were employed to assess the prognostic impact of PCMT1 on LIHC patients, and we investigated the association between PCMT1 and clinical features, which we validated using a GEO therapeutic dataset. Gene enrichment analysis helped identify signaling pathways associated with PCMT1 expression. Moreover, we evaluated the relationship between PCMT1 and immune cell infiltration, as well as the differences in gene mutations between high-expression and low-expression groups. In vitro and in vivo experiments were performed to assess the effect of PCMT1 on tumor cell lines and mouse tumor models, and potential pathways were explored through gene sequencing.

RESULT

PCMT1 is highly expressed in most tumors and exhibits a significant association with prognosis in LIHC patients. Pathway enrichment analysis revealed that PCMT1 is involved in cell cycle regulation, immunity, and other processes. Further immune analysis demonstrated that high expression of PCMT1 could reduce tumor-killing immune cell infiltration. In vitro experiments indicated that PCMT1 knockdown could inhibit cancer cell proliferation and migration while promoting apoptosis. In vivo experiments showed that PCMT1 knockdown significantly reduced tumor growth rate, enhanced CD8+T cell infiltration, and increased caspase-3 expression in the tumor area. Gene sequencing suggested that PCMT1 may function through the PI3K-AKT pathway.

CONCLUSION

Our findings suggest that PCMT1 acts as a promoter of liver cancer progression and may serve as a novel prognostic indicator and therapeutic target for patients with LIHC.

Biological effects of the loss of homochirality in a multicellular organism

Homochirality is a fundamental feature of all known forms of life, maintaining biomolecules (amino-acids, proteins, sugars, nucleic acids) in one specific chiral form. While this condition is central to biology, the mechanisms by which the adverse accumulation of non-L-α-amino-acids in proteins lead to pathophysiological consequences remain poorly understood. To address how heterochirality build-up impacts organism's health, we use chiral-selective in vivo assays to detect protein-bound non-L-α-amino acids (focusing on aspartate) and assess their functional significance in Drosophila. We find that altering the in vivo chiral balance creates a 'heterochirality syndrome' with impaired caspase activity, increased tumour formation, and premature death. Our work shows that preservation of homochirality is a key component of protein function that is essential to maintain homeostasis across the cell, tissue and organ level.

The Protein L-Isoaspartyl (D-Aspartyl) Methyltransferase Regulates Glial-to-Mesenchymal Transition and Migration Induced by TGF-β1 in Human U-87 MG Glioma Cells

The enzyme PIMT methylates abnormal aspartyl residues in proteins. U-87 MG cells are commonly used to study the most frequent brain tumor, glioblastoma. Previously, we reported that PIMT isoform I possessed oncogenic features when overexpressed in U-87 MG and U-251 MG glioma cells. Higher levels of wild-type PIMT stimulated migration and invasion in both glioma cell lines. Conversely, PIMT silencing reduced these migratory abilities of both cell lines. These results indicate that PIMT could play a critical role in glioblastoma growth. Here, we investigated for the first time, molecular mechanisms involving PIMT in the regulation of epithelial to mesenchymal transition (EMT) upon TGF-β1 treatments. Gene array analyses indicated that EMT genes but not PIMT gene were regulated in U-87 MG cells treated with TGF-β1. Importantly, PIMT silencing by siRNA inhibited in vitro migration in U-87 MG cells induced by TGF-β1. In contrast, overexpressed wild-type PIMT and TGF-β1 had additive effects on cell migration. When PIMT was inhibited by siRNA, this prevented Slug induction by TGF-β1, while Snail stimulation by TGF-β1 was increased. Indeed, overexpression of wild-type PIMT led to the opposite effects on Slug and Snail expression dependent on TGF-β1. These data highlighted the importance of PIMT in the EMT response dependent on TGF-β1 in U-87 MG glioma cells by an antagonist regulation in the expression of transcription factors Slug and Snail, which are critical players in EMT.

A standardized extract of cultured Lentinula edodes mycelia downregulates cortactin in gemcitabine-resistant pancreatic cancer cells

AHCC^®, a standardized extract of cultured Lentinula edodes mycelia, enhances the therapeutic effects and reduces the adverse effects of chemotherapy. Our previous study reported that treatment with AHCC^® downregulated the expression levels of tumor-associated proteins in the gemcitabine-resistant pancreatic cancer cell line, KLM1-R. However, to the best of our knowledge, the role of AHCC^® in the inhibition of cell migration remains unexplored. Cortactin (CTTN), an actin nucleation-promoting factor, has been reported to be upregulated and correlated with migration, invasion and metastasis in pancreatic cancer cells. The present study aimed to investigate the effects of AHCC^® on cell migration and the protein expression level of CTTN in KLM1-R cells. The Gene Expression Profiling Interactive Analysis (GEPIA2), an online bioinformatics platform, was used to analyze CTTN mRNA expression levels in pancreatic cancer tissues compared with normal pancreatic tissues. CTTN mRNA expression and its association with clinicopathological characteristics were assessed by using the GEPIA2 platform. Next, the effects of AHCC^® on KLM1-R cell migration were investigated by in vitro wound-healing assay. The KLM1-R cells were treated with AHCC^® at a concentration of 10 mg/ml for 48 h. Western blotting was performed on of cell lysates with anti-CTTN or anti-actin antibodies to assess the protein expression levels of CTTN. Bioinformatics analysis indicated that the mRNA expression level of CTTN increased in pancreatic cancer tissues. The increased mRNA expression levels of CTTN were inversely associated with clinicopathological characteristics, including disease stages and prolonged patient survival times. The administration of 10 mg/ml AHCC^® significantly inhibited KLM1-R cells migration compared with controls. The protein expression levels of CTTN were significantly reduced in AHCC^®-treated KLM1-R cells, whereas actin expression was not affected. The downregulation of CTTN indicated the anti-metastatic potential of AHCC^® in pancreatic cancer cells. Overall, AHCC^® may have the potential to be a complementary and alternative therapeutic approach in treating pancreatic cancer.