A novel amplification gene PCI domain containing 2 (PCID2) promotes colorectal cancer through directly degrading a tumor suppressor promyelocytic leukemia (PML)

Tumorigenesis Caused by Aberrant Expression of GANP, a Central Component in the Mammalian TREX-2 Complex-Lessons from Transcription-Coupled DNA Damages

DNA is frequently damaged by genotoxic stresses such as ionizing radiation, reactive oxygen species, and nitrogen species. DNA damage is a key contributor to cancer initiation and progression, and thus the precise and timely repair of these harmful lesions is required. Recent studies revealed transcription as a source of genome instability, and transcription-coupled DNA damage has been a focus in cancer research. Impaired mRNA export is closely related to DNA damage through R-loop formation. The molecular machineries of transcription-coupled DNA damage have been extensively analyzed in Saccharomyces cerevisiae. However, the molecular basis of these phenomena in higher eukaryotes remains elusive. In this review, we focus on the relationship between deregulated mRNA export through the transcription-export-2 (TREX-2) complex and cancer development. Particularly, the expression of germinal center-associated nuclear protein (GANP), a molecular scaffold in the TREX-2 complex, is highly associated with tumorigenesis in mice and humans. Although the deregulated expression of other components in the TREX-2 complex might affect cancer development, we have directly demonstrated the significance of GANP in tumorigenesis using genetically modified mice. Additionally, we describe recent evidence for medical applications demonstrating that the downregulation of the other components may be a good candidate for a chemotherapeutic target in terms of reducing the side effects.

Cancer-associated fibroblasts promote the proliferation and metastasis of colon cancer by mediating the RLIM/PML axis through paracrine COMP

BACKGROUND AND AIM

Cancer-associated fibroblasts (CAFs) are abundant in colon cancer (CC) patients with a poor prognosis. Here, the molecular regulatory mechanism of CAFs on CC growth and metastasis was explored.

METHODS

The genes' expression was monitored using RT-qPCR, immunoblotting, and immunohistochemistry. Cell viability and proliferation were found using CCK-8 and clone formation assays. The cell migration and invasion were probed using wound healing and Transwell. Co-IP was utilized for ascertaining the interaction between AKT and the ring finger protein, LIM domain interacting (RLIM). The in vivo murine subcutaneous tumor model and the metastasis model were built to further ascertain the axis.

RESULTS

The result showed that CAFs motivate the growth and activate the PI3K/AKT pathway of CC cells via paracrine cartilage oligomeric matrix protein (COMP). Moreover, RLIM promoted the growth of CC cells, and its protein stability was regulated by AKT through its phosphorylation. Further, RLIM facilitated the ubiquitination and degradation of promyelocytic leukemia protein (PML). The in vitro and in vivo tests found that PML overexpression could inhibit CC's growth and metastasis, which were enhanced by CAFs.

CONCLUSION

The COMP excreted from CAFs enhances the CC's growth and metastasis through regulating the RLIM/PML axis, supplying a new potential target for the cure of CC.

Prognostic model based on centrosome-related genes constructed in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the most common malignant tumor in the epithelium of the head and neck. The role of the centrosome in malignant tumors is crucial. However, research on the centrosome in HNSCC remains largely unexplored. In this study, bioinformatics tools were utilized to analyze the expression and prognostic significance of centrosome-related genes (CRGs). CRGs exhibited a relatively high mutation frequency in HNSCC. Consensus unsupervised clustering analysis based on the expression profiles of CRGs revealed significant associations with clinical features, prognosis and immune microenvironment in HNSCC. Prognostic features were constructed using univariate and LASSO Cox regression, resulting in a centrosome-related model with eleven features. Patients were classified into high-risk and low-risk groups based on median risk scores. External validation using the GSE41613 dataset from the GEO database confirmed the reliability of the centrosome-related model. The model was associated with the prognosis of HNSCC patients, and centrosome-related features could impact tumor prognosis by influencing the tumor immune microenvironment. Finally, qPCR showed that CRGs were highly expressed in tumor tissues. This study developed a novel centrosome-related prognostic model, applicable for predicting the prognosis and immune landscape of HNSCC patients, offering potential targets for future HNSCC treatment.

Evaluation of the gene fusion landscape in early onset sporadic rectal cancer reveals association with chromatin architecture and genome stability

Gene fusions represent a distinct class of structural variants identified frequently in cancer genomes across cancer types. Several gene fusions exhibit gain of oncogenic function and thus have been the focus of development of efficient targeted therapies. However, investigation of fusion landscape in early-onset sporadic rectal cancer, a poorly studied colorectal cancer subtype prevalent in developing countries, has not been performed. Here, we present a comprehensive landscape of gene fusions in EOSRC and CRC using patient derived tumor samples and data from The Cancer Genome Atlas, respectively. Gene Ontology analysis revealed enrichment of unique biological process terms associated with 5'- and 3'- fusion partner genes. Extensive network analysis highlighted genes exhibiting significant promiscuity in fusion formation and their association with chromosome fragile sites. Investigation of fusion formation in the context of global chromatin architecture unraveled a novel mode of gene activation that arose from fusion between genes located in orthogonal chromatin compartments. The study provides novel evidence linking fusions to genome stability and architecture and unearthed a hitherto unidentified mode of gene activation in cancer.

Comprehensive data mining reveals RTK/RAS signaling pathway as a promoter of prostate cancer lineage plasticity through transcription factors and CNV

Prostate cancer lineage plasticity is a key driver in the transition to neuroendocrine prostate cancer (NEPC), and the RTK/RAS signaling pathway is a well-established cancer pathway. Nevertheless, the comprehensive link between the RTK/RAS signaling pathway and lineage plasticity has received limited investigation. In particular, the intricate regulatory network governing the interplay between RTK/RAS and lineage plasticity remains largely unexplored. The multi-omics data were clustered with the coefficient of argument and neighbor joining algorithm. Subsequently, the clustered results were analyzed utilizing the GSEA, gene sets related to stemness, multi-lineage state datasets, and canonical cancer pathway gene sets. Finally, a comprehensive exploration of the data based on the ssGSEA, WGCNA, GSEA, VIPER, prostate cancer scRNA-seq data, and the GPSAdb database was conducted. Among the six modules in the clustering results, there are 300 overlapping genes, including 3 previously unreported prostate cancer genes that were validated to be upregulated in prostate cancer through RT-qPCR. Function Module 6 shows a positive correlation with prostate cancer cell stemness, multi-lineage states, and the RTK/RAS signaling pathway. Additionally, the 19 leading-edge genes of the RTK/RAS signaling pathway promote prostate cancer lineage plasticity through a complex network of transcriptional regulation and copy number variations. In the transcriptional regulation network, TP63 and FOXO1 act as suppressors of prostate cancer lineage plasticity, whereas RORC exerts a promoting effect. This study provides a comprehensive perspective on the role of the RTK/RAS pathway in prostate cancer lineage plasticity and offers new clues for the treatment of NEPC.

PCID2 dysregulates transcription and viral RNA processing to promote HIV-1 latency

HIV-1 latency results from tightly regulated molecular processes that act at distinct steps of HIV-1 gene expression. Here, we characterize PCI domain-containing 2 (PCID2) protein, a subunit of the transcription and export complex 2 (TREX2) complex, to enforce transcriptional repression and post-transcriptional blocks to HIV-1 gene expression during latency. PCID2 bound the latent HIV-1 LTR (long terminal repeat) and repressed transcription initiation during latency. Depletion of PCID2 remodeled the chromatin landscape at the HIV-1 promoter and resulted in transcriptional activation and latency reversal. Immunoprecipitation coupled to mass spectrometry identified PCID2-interacting proteins to include negative viral RNA (vRNA) splicing regulators, and PCID2 depletion resulted in over-splicing of intron-containing vRNA in cell lines and primary cells obtained from PWH. MCM3AP and DSS1, two other RNA-binding TREX2 complex subunits, also inhibit transcription initiation and vRNA alternative splicing during latency. Thus, PCID2 is a novel HIV-1 latency-promoting factor, which in context of the TREX2 sub-complex PCID2-DSS1-MCM3AP blocks transcription and dysregulates vRNA processing.

WP1066, a small molecule inhibitor of STAT3, chemosensitizes paclitaxel-resistant ovarian cancer cells to paclitaxel by simultaneously inhibiting the activity of STAT3 and the interaction of STAT3 with Stathmin

Paclitaxel is widely used to treat cancer, however, drug resistance limits its clinical utility. STAT3 is constitutively activated in some cancers, and contributes to chemotherapy resistance. Currently, several STAT3 inhibitors including WP1066 are used in cancer clinical trials. However, whether WP1066 reverses paclitaxel resistance and the mechanismremains unknown. Here, we report that in contrast to paclitaxel-sensitive parental cells, the expressions of several pro-survival BCL2 family members such as BCL-2, BCL-XL and MCL-1 are higher in paclitaxel-resistant ovarian cancer cells. Meanwhile, STAT3 is constitutively activated while stathmin loses its activity in paclitaxel-resistant cells. Importantly, WP1066 amplifies the inhibition of cell proliferation, colony-forming ability and apoptosis of ovarian cancer cells induced by paclitaxel. Mechanistically, WP1066, on the one hand, interferes the STAT3/Stathmin interaction, causing unleash of STAT3/Stathmin from microtubule, thus destroying microtubule stability. This process results in reduction of Ac-α-tubulin, further causing MCL-1 reduction. On the other hand, WP1066 inhibits phosphorylation of STAT3 by JAK2, and blocks its nuclear translocation, therefore repressing the transcription of pro-survival targets such as BCL-2, BCL-XL and MCL-1. Finally, the two pathways jointly promote cell death. Our findings reveal a new mechanism wherein WP1066 reverses paclitaxel-resistance of ovarian cancer cells by dually inhibiting STAT3 activity and STAT3/Stathmin interaction, which may layfoundation for WP1066 combined with paclitaxel in treating paclitaxel-resistant ovarian cancer.

[PCID2 is highly expressed in gastric cancer and affects the prognosis by regulating cancer cell cycle and proliferation]

OBJECTIVE

To investigate the expression of PCI Domain Containing 2 (PCID2) in gastric cancer, its effect on gastric cancer cell cycle and proliferation and the possible molecular mechanisms.

METHODS

We examined PCID2 expression levels in gastric cancer and adjacent tissues from 100 patients undergoing radical gastrectomy in our hospital between January, 2012 and December, 2016, and analyzed the correlation of PCID2 expression level with cancer progression and postoperative 5-year survival rate of the patients. GO enrichment analysis was performed to identify the possible pathways that mediated the effect of PCID2 in gastric cancer progression. The effects of lentivirus-mediated PCID2 knockdown and overexpression on cell proliferation and cell cycle were analyzed in gastric cancer MGC-803 cells and in nude mice.

RESULTS

PCID2 was highly expressed in gastric cancer tissues and positively correlated with peripheral blood levels of CA19-9 and CEA (P < 0.01). In gastric cancer patients, a high PCID2 expression was associated with a significantly lowered postoperative 5-year survival rate (P < 0.001) as an independent risk factor for postoperative survival (HR: 2.987, 95% CI: 1.616-5.519). The sensitivity, specificity, and area under the curve of PCID2 for predicting postoperative 5-year survival were 76.74%, 75.44%, and 0.755 (P < 0.001), respectively. GO enrichment analysis suggested that PCID2 was associated with gastric cancer cell cycle progression. PCID2 overexpression in MGC-803 cells significantly promoted cell proliferation, G1/S phase transition, expressions of cyclin D1 and CDK6, and the growth of transplanted xenograft in nude mice (P < 0.05). The expressions of p27 and p16 were significantly lowered in gastric cancer tissues, and their expression levels were negatively regulated by PCID2 expression in MGC-803 cells (P < 0.05).

CONCLUSION

PCID2 is highly expressed in gastric cancer tissues in close correlation with poor prognosis of the patients. High PCID2 expression promotes gastric cancer proliferation and cell cycle progression by inhibiting the expression of p27 and p16.