PYGO2 as an independent diagnostic marker expressed in a majority of colorectal cancers

PYGO2 as a novel prognostic biomarker and its correlation with immune infiltrates in liver cancer

OBJECTIVE

The PYGO2 gene plays a significant role in various cancers. However, its prognostic significance and involvement in immune infiltration in liver cancer remain unclear. This study aimed to comprehensively evaluate PYGO2 expression and its associations with prognosis and clinicopathological features in liver cancer.

METHODS

Data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases were analyzed. Functional enrichment analysis and immune cell infiltration assessments were performed to explore potential pathogenic mechanisms.

RESULTS

PYGO2 was highly expressed in multiple cancer types, including bladder urothelial carcinoma, breast invasive carcinoma, cholangiocarcinoma, diffuse large B-cell lymphoma, and liver cancer. Analysis of 50 paired liver cancer tissues from TCGA revealed significant upregulation of PYGO2 expression. Moreover, high PYGO2 expression was significantly associated with pathological T stage, overall pathological stage, tumor status, and race. Kaplan-Meier survival analysis showed that low PYGO2 expression correlated with improved overall survival (OS), disease-specific survival (DSS), and progression-free interval (PFI) in liver cancer patients. Functional enrichment analysis identified several enriched pathways, including the reactive oxygen species signaling pathway, MYC targets, interferon-alpha response, immune response regulation signaling pathway, and leukocyte migration. Additionally, PYGO2 overexpression was associated with lower proportions of cytotoxic cells, dendritic cells, immature dendritic cells, mast cells, neutrophils, plasmacytoid dendritic cell-like cells, Th17 cells, and regulatory T cells, but a higher proportion of Th2 cells. Furthermore, the high PYGO2 expression group exhibited increased immune checkpoint gene expression, particularly PDCD1.

CONCLUSION

PYGO2 is a promising prognostic biomarker for liver cancer, given its strong associations with clinicopathological features, survival outcomes, and immune-related characteristics.

PYGO2 promotes resistance to chemotherapy via reducing apoptosis and G2/M cell cycle arrest in esophageal carcinoma cells

5-FU is a widely used chemotherapy drug for esophageal carcinomas, but therapy failure has been observed in 5-FU-resistant patients. Overcoming this resistance is a significant challenge in cancer treatment, requiring identifying and targeting important resistance mechanisms. PYGO2 expression is crucial in developing resistance to various chemotherapy drugs. In this study, we aimed to investigate the impact of PYGO2 overexpression on the sensitivity of YM-1 and KYSE-30 esophageal carcinoma cells against 5-FU. To do this, we compared cell viability, cell cycle arrest, apoptosis rate, and mRNA expressions of various apoptosis-related genes between pcDNA3-PYGO2 transfected and untransfected KYSE-30 and YM-1 esophageal carcinoma cells following treatment with 5-FU. We showed that PYGO2 expression reduces 5-FU sensitivity in YM-1 and KYSE-30 cells. PYGO2-overexpressing cells treated with 5-FU have exhibited a noteworthy reduction in both early and late apoptotic cells compared to controls. Furthermore, a significant decrease in the Bax/Bcl2 ratio and P53 gene expression was observed. 5-FU induces G2/M cell cycle arrest in YM-1 and KYSE-30 cells. However, PYGO2 overexpression impeded G2/M cell cycle arrest in 5-FU-treated cells, thereby suppressing the toxicity of 5-FU. PYGO2 may mediate its apoptotic effect by regulating cell cycle regulatory proteins, specifically cyclin D1 and p21. These results highlight PYGO2's capacity to alter how esophageal cancer cells respond to 5-FU therapy, emphasizing its importance as a potential focal point for treatment strategies.

PYGO2 increases proliferation and migration capacities through critical signaling pathways in esophageal squamous cell carcinoma

Esophageal cancer, an increasingly prevalent malignancy, is a major concern for global health. The development of esophageal squamous cell carcinoma (ESCC) involves various genetic abnormalities that affect key cell signaling pathways, including Wnt, Hh, Apoptosis, MAPK, EGFR, AKT, Notch, and EMT. Additionally, this malignancy involves some changes in the expression of long noncoding RNAs (LncRNAs). The present study examines the relationship between PYGO2 gene expression and the activity of cell signaling pathways in KYSE-30 and YM-1ESCC cell lines. To this end, several cellular and molecular tests were performed, including cell migration, cell cycle, and apoptosis. Also, expression levels of CD133 and CD44 markers, real-time PCR, and western blot were analyzed after inducing PYGO2 protein expression in the cells. Overexpression of the PYGO2 protein resulted in the upregulation of Wnt pathway-related genes, leading to enhanced cell migration and proliferation and reduced apoptosis in both cell lines. Furthermore, PYGO2 gene expression induction analysis showed the correlation of several involved genes in Wnt, Hh, Apoptosis, MAPK, EGFR, AKT, and EMT pathways with various LncRNAs.

Structural basis of the interaction between BCL9-Pygo and LDB-SSBP complexes in assembling the Wnt enhanceosome

The Wnt enhanceosome is responsible for transactivation of Wnt-responsive genes and a promising therapeutic target for treatment of numerous cancers with Adenomatous Polyposis Coli (APC) or β-catenin mutations. How the Wnt enhanceosome is assembled remains poorly understood. Here we show that B-cell lymphoma 9 protein (BCL9), Pygopus (Pygo), LIM domain-binding protein 1 (LDB1) and single-stranded DNA-binding protein (SSBP) form a stable core complex within the Wnt enhanceosome. Their mutual interactions rely on a highly conserved N-terminal asparagine proline phenylalanine (NPF) motif of Pygo, through which the BCL9-Pygo complex binds to the LDB-SSBP core complex. Our crystal structure of a ternary complex comprising the N-terminus of human Pygo2, LDB1 and SSBP2 reveals a single LDB1-SSBP2 complex binding simultaneously to two Pygo2 molecules via their NPF motifs. These interactions critically depend on the NPF motifs which bind to a deep groove formed between LDB1 and SSBP2, potentially constituting a binding site for drugs blocking Wnt/β-catenin signaling. Analysis of human cell lines lacking LDB or Pygo supports the functional relevance of the Pygo-LDB1-SSBP2 interaction for Wnt/β-catenin-dependent transcription.