In vitro Anti-malignant Property of PCMT1 Silencing and Identification of the SNHG16/miR-195/PCMT1 Regulatory Axis in Breast Cancer Cells

PCMT1 as a prognostic marker in breast cancer

INTRODUCTION

Triple-negative breast cancer (TNBC) is one of the most aggressive cancers in women, therefore it is necessary to determine novel prognostic markers to estimate survival and advancement the treatment of the disease. Recently, PCMT1, a protein mediating TNBC immune infiltration, has gained attention as a potential therapeutic target. The aim of the study was to demonstrate the relationship between PCMT1 protein overexpression as a prognostic indicator for patients with TNBC cancer and patient survival.

MATERIALS AND METHODS

The study included 64 samples collected from 64 TNBC patients. We used the ImageJ software with the IHC Profiler driver for image analysis. To improve the reliability of the results, we expanded the analysis by including The Cancer Genome Atlas cohort.

RESULTS

We observed strong PCMT1 immunoreactivity in breast cancer samples and PCMT1 expression in TNBC was significantly higher than in the control group. Patients with high PCMT1 expression had a significantly lower overall survival rate (60.62% vs. 90.35%, respectively) than patients with low PCMT1 expression. In our study and TCGA groups, PCMT1 expression did not correlate with lymph node involvement and distant metastases but correlated with tumor stage. The results obtained in a larger TCGA group are consistent with those in our research group. Overexpression of PCMT1 was a prognostic marker of shorter survival in patients with TNBC.

CONCLUSIONS

The overexpression of the PCMT1 protein in triple negative breast cancer significantly correlated with shorter overall survival. The confirmed association could be a potential prognostic biomarker for patients with TNBC.

Silencing PCMT1 enhances the sensitivity of breast cancer cells to paclitaxel through the PI3K/Akt/STMN1 pathway

This study aimed to investigate whether silencing Protein L-isoaspartate (D-aspartate) O-methyltransferase (PCMT1) expression can enhance the sensitivity of breast cancer cells to paclitaxel and its possible mechanism. Tumor tissues and adjacent histologically normal tissues were collected from patients with breast cancer admitted to our hospital. Human normal breast epithelial cells MCF10A, human breast cancer cells MCF-7, and paclitaxel-resistant breast cancer cells MCF-7/PR were purchased. MCF-7/PR cells were further grouped into negative control (NC) group, si-PCMT1 group (transfected with si-PCMT1), 740Y-P group (treated with 740Y-P, an activator of phosphatidylinositol 3-kinase (PI3K)/ v-Akt Murine Thymoma Viral Oncogene (AKT) signaling pathway), and si-PCMT1 + 740Y-P group (transfected with si-PCMT1 and then treated with 740Y-P). The expression level of PCMT1 in tissues and cells was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Western blot analysis was used to detect the protein expression level of PCMT1 in tissues and cells as well as the protein level of p-PI3K, PI3K, p-Akt, Akt, and Stathmin1 (STMN1) in cells. 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT) and colony formation assays were used to determine cell viability, scratch assay was used to assess the migration ability of cells, and Transwell assay was used to assess the invasion ability of cells. The expression of PCMT1 was remarkably up-regulated in breast cancer tissues and MCF-7/PR cells. Silencing PCMT1 expression significantly inhibited the proliferation, migration, and invasion of MCF-7/PR cells, and alleviated the resistance of cancer cells to paclitaxel. Additionally, silencing PCMT1 expression also inhibited the activation of PI3K/Akt/STMN1 pathway in MCF-7/PR cells, while activating PI3K/Akt/STMN1 pathway significantly reversed the effect of silencing PCMT1 expression on MCF-7/PR cells. PCMT1 is highly expressed in breast cancer tissues and MCF-7/PR cells, and silencing PCMT1 expression can not only inhibit the development of breast cancer but also enhance paclitaxel sensitivity. Its mechanism of action may be achieved by inhibiting PI3K/Akt/STMN1 signaling.

[Prognostic Value of PCMT1 Expression in Gastric Cancer and Its Regulatory Effect on Spindle Assembly Checkpoints]

Objective

The study was conducted to investigate the expression of protein-L-isoaspartate (D-aspartate) O-methyltransferase (PCMT1) in gastric cancer and its effect on the prognosis, and to analyze its potential mechanism.

Methods

UALCAN, a cancer data analysis platform, was used to conduct online analysis of the expression of PCMT1 in gastric cancer tissues. Through the Database for Annotation, Visualization and Integrated Discovery (DAVID), Gene Ontology (GO) annotation and signaling pathway enrichment by Kyoto Encyclopedia of Genes and Genomes (KEGG) were performed to analyze the possible functions and signaling pathways. A total of 120 patients who underwent radical gastrectomy for gastric cancer between January 2014 and December 2017 in our hospital were enrolled for the study. Immunohistochemical staining was performed to determine the expression of PCMT1 and Ki67 in gastric cancer tissues. Cox regression, Kaplan-Meier curve, and receiver operating characteristic (ROC) curves were used for prognostic analysis of 5-year survival in gastric cancer patients after surgery. Lentivirus was used to construct PCMT1-interfering or PCMT1-overexpressing vectors, which were then used to transfect human gastric cancer cell lines of MGC-803 and HGC-27 cells. The interfering empty vector (sh-NC) group, the interfering PCMT1 vector (sh-PCMT1) group, the overexpressing empty vector (LV-Vec) group, and the overexpressing PCMT1 vector (LV-PCMT1) group were set up. Western blot was performed to determine the protein expression levels of PCMT1, CyclinB1, and CDC20. CCK-8 assay was performed to measure the proliferation of gastric cancer cells. Flow cytometry was performed to determine the cell cycle. MGC-803 cells were injected in four groups of nude mice to construct a subcutaneous xenograft tumor model, with three nude mice in each group. The body mass of the nude mice was measured. The nude mice were sacrificed after 14 days and the tumor volume was monitored. The expression levels of CyclinB1 and CDC20 proteins in the tumor tissues were determined by Western blot assay.

Results

Analysis with UALCAN showed that PCMT1 was highly expressed in gastric cancer tissues. Moreover, elevated expression was found in gastric tumor tissues of different pathological stages and grades and those with lymph node metastasis (P<0.05). GO and KEGG enrichment analyses showed that PCMT1 was mainly involved in the signal regulation of mitosis, spindle assembly checkpoints, and cell cycle. The immunohistochemical results showed that PCMT1 and Ki67 were highly expressed in gastric cancer tissues and that they were positively correlated with each other (P<0.05). Cox multivariate analysis showed that high PCMT1 expression (hazard ratio [HR]=2.921, 95% confidence interval [CI]:1.628-5.239) was one of the independent risk factors affecting the 5-year survival rate of gastric cancer patients after surgery. Kaplan-Meier curve showed that patients with high PCMT1 expression had a lower 5-year survival after surgery (16.7%, HR=4.651, 95% CI: 2.846-7.601) than patients with low PCMT1 expression (70.0%, HR=0.215, 95% CI: 0.132-0.351) did. The ROC curve showed that PCMT1 had an area under the curve (AUC) of 0.764 (95% CI: 0.674-0.854) for predicting 5-year patient survival after surgery. Western blot results showed that lentiviral interference or overexpression of PCMT1 cell lines was successfully constructed. The results of CCK-8 showed that the proliferative ability of MGC-803 and HGC-27 cells was weakened with the downregulation of PCMT1, and the overexpression of PCMT1 promoted cell proliferation (P<0.05). With the interference of PCMT1, the expression of CDC20 protein was decreased, the expression of CyclinB1 protein was increased, and the cell cycle was arrested in the G2/M phase. In contrast, the overexpression of PCMT1 led to the opposite trends (P<0.05). In the sh-PCMT1 group, the tumor volume and mass were decreased and the expression of CDC20 protein was decreased and the expression of CyclinB1 protein was increased in the tumor tissues of the nude mice (P<0.05, compared with those of the sh-NC group. In contrast, the LV-PCMT1 group showed the opposite trends (P<0.05, compared with those of the LV-Vec group).

Conclusion

The high expression of PCMT1 in gastric cancer tissues is associated with poor prognosis in patients and may affect tumor cell malignant proliferation via regulating spindle checkpoints in the process of mitosis.

PCMT1 knockdown attenuates malignant properties by globally regulating transcriptome profiles in triple-negative breast cancer cells

Background

As the most frequently diagnosed cancer in women, Breast cancer has high mortality and metastasis rate, especially triple-negative breast cancer (TNBC). As an oncogene, protein-L-isoaspartate (D-aspartate) O-methyltransferase (PCMT1) is a prognostic biomarker in breast cancer and is highly expressed, while its underlying functions remain unknown.

Methods

In this study, we silenced PCTM1 in TNBC MDA-MB-231 cells by short hairpin RNA (shPCMT1) to investigate its cellular functions using cell proliferation, apoptosis, migration, and invasion experiments. Following this, the transcriptome sequencing (RNA-seq) experiment was conducted to explore the molecular targets of PCMT1, including differentially expressed genes (DEGs) and regulated alternative splicing events (RASEs).

Results

The results showed that shPCMT1 inhibited the proliferation, migration, and invasion of MDA-MB-231 cells. We obtained 1,084 DEGs and 2,287 RASEs between shPCMT1 and negative control (NC) groups through RNA-seq. The DEGs were significantly enriched in immune or inflammation response and cell adhesion-associated pathways, pathways associated with PCMT1 cellular function in cell migration. The RASE genes were enriched in cell cycle-associated pathways and were associated with the altered cell proliferation rate. We finally validated the changed expression and splicing levels of DEGs and RASEs. We found that 34 RNA binding protein (RBP) genes were dysregulated by shPCMT1, including NQO1, S100A4, EEF1A2, and RBMS2. The dysregulated RBP genes could partially explain how PCMT1 regulates the global transcriptome profiles.

Conclusion

In conclusion, our study identified the molecular targets of PCMT1 in the TNBC cell line, expands our understanding of the regulatory mechanisms of PCMT1 in cancer progression, and provides novel insights into the progression of TNBC. The identified molecular targets are potential therapeutic targets for future TNBC treatment.

Patients with Systemic Juvenile Idiopathic Arthritis (SJIA) Show Differences in Autoantibody Signatures Based on Disease Activity

Systemic juvenile idiopathic arthritis (SJIA) is a severe rheumatic disease in children. It is a subgroup of juvenile idiopathic arthritis (JIA; MIM #604302), which is the most common rheumatic disease in children. The diagnosis of SJIA often comes with a significant delay, and the classification between autoinflammatory and autoimmune disease is still discussed. In this study, we analyzed the immunological responses of patients with SJIA, using human proteome arrays presenting immobilized recombinantly expressed human proteins, to analyze the involvement of autoantibodies in SJIA. Results from group comparisons show several differentially reactive antigens involved in inflammatory processes. Intriguingly, many of the identified antigens had a high reactivity against proteins involved in the NF-κB pathway, and it is also notable that many of the detected DIRAGs are described as dysregulated in rheumatoid arthritis. Our data highlight novel proteins and pathways potentially dysregulated in SJIA and offer a unique approach to unraveling the underlying disease pathogenesis in this chronic arthropathy.