Prognostic significance and biological function of Lamina-associated polypeptide 2 in non-small-cell lung cancer

Unveiling the roles of LEMD proteins in cellular processes

Proteins localized in the inner nuclear membrane (INM) engage in various fundamental cellular processes via their interactions with outer nuclear membrane (ONM) proteins and nuclear lamina. LAP2-emerin-MAN1 domain (LEMD) family proteins, predominantly positioned in the INM, participate in the maintenance of INM functions, including the reconstruction of the nuclear envelope during mitosis, mechanotransduction, and gene transcriptional modulation. Malfunction of LEMD proteins leads to severe tissue-restricted diseases, which may manifest as fatal deformities and defects. In this review, we summarize the significant roles of LEMD proteins in cellular processes, explains the mechanisms of LEMD protein-related diseases, and puts forward questions in less-explored areas like details in tissue-restricted phenotypes. It intends to sort out previous works about LEMD proteins and pave way for future researchers who might discover deeper mechanisms of and better treatment strategies for LEMD protein-related diseases.

Epigenetic silencing of KCTD8 promotes hepatocellular carcinoma growth by activating PI3K/AKT signaling

Aim: The aim of current study is to explore the epigenetic changes and function of KCTD8 in human hepatocellular carcinoma (HCC). Materials & methods: HCC cell lines and tissue samples were employed. Methylation specific PCR, flow cytometry, immunoprecipitation and xenograft mouse models were used.Results: KCTD8 was methylated in 44.83% (104/232) of HCC and its methylation may act as an independent poor prognostic marker. KCTD8 expression was regulated by DNA methylation. KCTD8 suppressed HCC cell growth both in vitro and in vivo via inhibiting PI3K/AKT pathway.Conclusion: Methylation of KCTD8 is an independent poor prognostic marker, and epigenetic silencing of KCTD8 increases the malignant tendency in HCC.

Mechanotransduction and epigenetic modulations of chromatin: Role of mechanical signals in gene regulation

Mechanical forces may be generated within a cell due to tissue stiffness, cytoskeletal reorganization, and the changes (even subtle) in the cell's physical surroundings. These changes of forces impose a mechanical tension within the intracellular protein network (both cytosolic and nuclear). Mechanical tension could be released by a series of protein-protein interactions often facilitated by membrane lipids, lectins and sugar molecules and thus generate a type of signal to drive cellular processes, including cell differentiation, polarity, growth, adhesion, movement, and survival. Recent experimental data have accentuated the molecular mechanism of this mechanical signal transduction pathway, dubbed mechanotransduction. Mechanosensitive proteins in the cell's plasma membrane discern the physical forces and channel the information to the cell interior. Cells respond to the message by altering their cytoskeletal arrangement and directly transmitting the signal to the nucleus through the connection of the cytoskeleton and nucleoskeleton before the information despatched to the nucleus by biochemical signaling pathways. Nuclear transmission of the force leads to the activation of chromatin modifiers and modulation of the epigenetic landscape, inducing chromatin reorganization and gene expression regulation; by the time chemical messengers (transcription factors) arrive into the nucleus. While significant research has been done on the role of mechanotransduction in tumor development and cancer progression/metastasis, the mechanistic basis of force-activated carcinogenesis is still enigmatic. Here, in this review, we have discussed the various cues and molecular connections to better comprehend the cellular mechanotransduction pathway, and we also explored the detailed role of some of the multiple players (proteins and macromolecular complexes) involved in mechanotransduction. Thus, we have described an avenue: how mechanical stress directs the epigenetic modifiers to modulate the epigenome of the cells and how aberrant stress leads to the cancer phenotype.

CLDN5 identified as a biomarker for metastasis and immune infiltration in gastric cancer via pan-cancer analysis

BACKGROUND

CLDN5 protein is essential for the formation of tight junctions in epithelial cells, and has been associated with epithelial-mesenchymal transition. Research has indicated that CLDN5 is associated with tumor metastasis, the tumor microenvironment, and immunotherapy in multiple types of cancer. Also, no comprehensive evaluation of the expression of CLDN5 and immunotherapy signatures through a pan-cancer analysis or immunoassay has been performed.

METHODS

We explored CLDN5's differential expression, survival analysis and clinicopathological staging through the TCGA database, and then corroborated the expression of CLDN5 by utilizing the GEO (Gene expression omnibus) database. To analyze CLDN5 KEGG, GO, and Hallmark mutations, as well as TIMER for immune infiltration, GSEA was utilized with ROC curve, mutation, and other factors such as survival, pathological stage, TME, MSI, TMB, immune cell infiltration, and DNA methylation. Immunohistochemistry was used to assess CLDN5 staining in gastric cancer tissues and paracancerous tissues. Visualization was done with R version 4.2.0 (http://www.rproject.org/).

RESULTS

According to TCGA database, CLDN5 expression levels differed significantly between cancer and normal tissues, and the GEO database (GSE49051 and GSE 64951) and tissue microarrays confirmed this result. Infiltrating cluster of differentiation 8+ (CD8+) T cells, CD4+ cells, neutrophils, dendritic cells, and macrophages revealed a correlation with CLDN5 expression. DNA methylation, TMB, and MSI are related to CLDN5 expression. Based on the ROC curve analysis, CLDN5 demonstrates outstanding diagnostic effectiveness for gastric cancer and is comparable to CA-199.

CONCLUSIONS

The findings suggest that CLDN5 is implicated in the oncogenesis of diverse cancer types, underscoring its potential significance in cancer biology. Notably, CLDN5 could have implications in immune filtration and immune checkpoint inhibitor therapies, however, further research is needed to confirm this.

Silencing effects of mutant RAS signalling on transcriptomes

Mutated genes of the RAS family encoding small GTP-binding proteins drive numerous cancers, including pancreatic, colon and lung tumors. Besides the numerous effects of mutant RAS gene expression on aberrant proliferation, transformed phenotypes, metabolism, and therapy resistance, the most striking consequences of chronic RAS activation are changes of the genetic program. By performing systematic gene expression studies in cellular models that allow comparisons of pre-neoplastic with RAS-transformed cells, we and others have estimated that 7 percent or more of all transcripts are altered in conjunction with the expression of the oncogene. In this context, the number of up-regulated transcripts approximates that of down-regulated transcripts. While up-regulated transcription factors such as MYC, FOSL1, and HMGA2 have been identified and characterized as RAS-responsive drivers of the altered transcriptome, the suppressed factors have been less well studied as potential regulators of the genetic program and transformed phenotype in the breadth of their occurrence. We therefore have collected information on downregulated RAS-responsive factors and discuss their potential role as tumor suppressors that are likely to antagonize active cancer drivers. To better understand the active mechanisms that entail anti-RAS function and those that lead to loss of tumor suppressor activity, we focus on the tumor suppressor HREV107 (alias PLAAT3 [Phospholipase A and acyltransferase 3], PLA2G16 [Phospholipase A2, group XVI] and HRASLS3 [HRAS-like suppressor 3]). Inactivating HREV107 mutations in tumors are extremely rare, hence epigenetic causes modulated by the RAS pathway are likely to lead to down-regulation and loss of function.

LncRNA TMPO-AS1 promotes esophageal squamous cell carcinoma progression by forming biomolecular condensates with FUS and p300 to regulate TMPO transcription

Esophageal squamous cell carcinoma (ESCC) is one of the most life- and health-threatening malignant diseases worldwide, especially in China. Long noncoding RNAs (lncRNAs) have emerged as important regulators of tumorigenesis and tumor progression. However, the roles and mechanisms of lncRNAs in ESCC require further exploration. Here, in combination with a small interfering RNA (siRNA) library targeting specific lncRNAs, we performed MTS and Transwell assays to screen functional lncRNAs that were overexpressed in ESCC. TMPO-AS1 expression was significantly upregulated in ESCC tumor samples, with higher TMPO-AS1 expression positively correlated with shorter overall survival times. In vitro and in vivo functional experiments revealed that TMPO-AS1 promotes the proliferation and metastasis of ESCC cells. Mechanistically, TMPO-AS1 bound to fused in sarcoma (FUS) and recruited p300 to the TMPO promoter, forming biomolecular condensates in situ to activate TMPO transcription in cis by increasing the acetylation of histone H3 lysine 27 (H3K27ac). Targeting TMPO-AS1 led to impaired ESCC tumor growth in a patient-derived xenograft (PDX) model. We found that TMPO-AS1 is required for cell proliferation and metastasis in ESCC by promoting the expression of TMPO, and both TMPO-AS1 and TMPO might be potential biomarkers and therapeutic targets in ESCC.

The role of a regulatory RNA in promoting esophageal squamous cell carcinoma (ESCC) has been clarified, revealing molecular details that might help in cancer diagnosis and treatment. Xiao-Jing Luo and colleagues at Sun Yat-sen University in China found that overproduction of an RNA molecule called thymopoietin-antisense RNA 1 (TMPO-AS1) in ESCC tissue samples from cancer patients was associated with shorter survival times. Overproduction of this RNA promoted proliferation and spread (metastasis) of the cancer cells. Research on details of the molecular mechanisms involved showed that the RNA ultimately activated the gene that codes for the protein hormone thymopoietin, which has previously been linked with various cancers. The authors suggest that TMPO-AS1 and thymopoietin could serve as diagnostic biomarkers of cancer and become targets for anti-cancer drugs.

Inner nuclear membrane protein TMEM201 promotes breast cancer metastasis by positive regulating TGFβ signaling

Emerging evidence shows the association between nuclear envelope and tumor progression, however, the functional contributions of specific constituents of the nuclear envelope remain largely unclear. We found that the expression level of transmembrane protein 201 (TMEM201), an integral inner nuclear membrane protein of unknown function, was significantly elevated in invasive breast cancer and predicted poor breast cancer prognosis. We showed that TMEM201, as a positive modulator, was both necessary and sufficient to regulate the migration and invasion of breast cancer cells in vitro and in vivo. Mechanistically, RNA-sequencing analysis and validation showed that TMEM201 deficiency inhibited epithelial-to-mesenchymal transition and transforming growth factor-β signaling. Finally, we showed that TMEM201 physically interacted with SMAD2/3 and was required for the phosphorylation of SMAD2/3, nuclear translocation and transcriptional activation of the TGFβ. Thus, we demonstrated that specific inner nuclear membrane component mediated signal-dependent transcriptional effects to control breast cancer metastasis.

miRGTF-net: Integrative miRNA-gene-TF network analysis reveals key drivers of breast cancer recurrence

Analysis of regulatory networks is a powerful framework for identification and quantification of intracellular interactions. We introduce miRGTF-net, a novel tool for construction of miRNA-gene-TF networks. We consider multiple transcriptional and post-transcriptional interaction types, including regulation of gene and miRNA expression by transcription factors, gene silencing by miRNAs, and co-expression of host genes with their intronic miRNAs. The underlying algorithm uses information on experimentally validated interactions as well as integrative miRNA/mRNA expression profiles in a given set of samples. The latter ensures simultaneous tissue-specificity and biological validity of interactions. We applied miRGTF-net to paired miRNA/mRNA-sequencing data of breast cancer samples from The Cancer Genome Atlas (TCGA). Together with topological analysis of the constructed network we showed that considered players can form reliable prognostic gene signatures for ER-positive breast cancer. A number of signatures demonstrated remarkably high accuracy on transcriptomic data obtained by both microarrays and RNA sequencing from several independent patient cohorts. Furthermore, an essential part of prognostic genes were identified as direct targets of transcription factor E2F1. The putative interplay between estrogen receptor alpha and E2F1 was suggested as a potential recurrence factor in patients treated with tamoxifen. Source codes of miRGTF-net are available at GitHub (https://github.com/s-a-nersisyan/miRGTF-net).