Downregulation of SPTAN1 is related to MLH1 deficiency and metastasis in colorectal cancer

Cancer-Specific Alterations in Nuclear Matrix Proteins Determined by Multi-omics Analyses of Ductal Carcinoma in Situ

Breast cancer (BC) is the most common cancer affecting women in the United States. Ductal carcinoma in situ (DCIS) is the earliest identifiable pre-invasive BC lesion. Estimates show that 14 to 50% of DCIS cases progress to invasive BC. Our objective was to identify nuclear matrix proteins (NMP) with specifically altered expression in DCIS and later stages of BC compared to non-diseased breast reduction mammoplasty and a contralateral breast explant using mass spectrometry and RNA sequencing to accurately identify aggressive DCIS. Sixty NMPs were significantly differentially expressed between the DCIS and non-diseased breast epithelium in an isogenic contralateral pair of patient-derived extended explants. Ten of the sixty showed significant mRNA expression level differences that matched the protein expression. These 10 proteins were similarly expressed in non-diseased breast reduction cells. Three NMPs (RPL7A, RPL11, RPL31) were significantly upregulated in DCIS and all other BC stages compared to the matching contralateral breast culture and an unrelated non-diseased breast reduction culture. RNA sequencing analyses showed that these three genes were upregulated increasingly with BC progression. Finally, we identified three NMPs (AHNAK, CDC37 and DNAJB1) that were significantly downregulated in DCIS and all other BC stages compared to the isogenically matched contralateral culture and the non-diseased breast reduction culture using both proteomics and RNA sequencing techniques.

A conserved motif in the disordered linker of human MLH1 is vital for DNA mismatch repair and its function is diminished by a cancer family mutation

DNA mismatch repair (MMR) is essential for correction of DNA replication errors. Germline mutations of the human MMR gene MLH1 are the major cause of Lynch syndrome, a heritable cancer predisposition. In the MLH1 protein, a non-conserved, intrinsically disordered region connects two conserved, catalytically active structured domains of MLH1. This region has as yet been regarded as a flexible spacer, and missense alterations in this region have been considered non-pathogenic. However, we have identified and investigated a small motif (ConMot) in this linker which is conserved in eukaryotes. Deletion of the ConMot or scrambling of the motif abolished mismatch repair activity. A mutation from a cancer family within the motif (p.Arg385Pro) also inactivated MMR, suggesting that ConMot alterations can be causative for Lynch syndrome. Intriguingly, the mismatch repair defect of the ConMot variants could be restored by addition of a ConMot peptide containing the deleted sequence. This is the first instance of a DNA mismatch repair defect conferred by a mutation that can be overcome by addition of a small molecule. Based on the experimental data and AlphaFold2 predictions, we suggest that the ConMot may bind close to the C-terminal MLH1-PMS2 endonuclease and modulate its activation during the MMR process.

Label-Free Proteomics of Oral Mucosa Tissue to Identify Potential Biomarkers That Can Flag Predilection of Precancerous Lesions to Oral Cell Carcinoma: A Preliminary Study

Oral squamous cell carcinomas are mostly preceded by precancerous lesions such as leukoplakia and erythroplakia. Our study is aimed at identifying potential biomarker proteins in precancerous lesions of leukoplakia and erythroplakia that can flag their transformation to oral cancer. Four biological replicate samples from clinical phenotypes of healthy control, leukoplakia, erythroplakia, and oral carcinoma were annotated based on clinical screening and histopathological evaluation of buccal mucosa tissue. Differentially expressed proteins were delineated using a label-free quantitative proteomic experiment done on an Orbitrap Fusion Tribrid mass spectrometer in three technical replicate sets of samples. Raw files were processed using MaxQuant version 2.0.1.0, and downstream analysis was done via Perseus version 1.6.15.0. Validation included functional annotation based on biological processes and pathways using the ClueGO plug-in of Cytoscape. Hierarchical clustering and principal component analysis were performed using the ClustVis tool. Across control, leukoplakia, and cancer, L-lactate dehydrogenase A chain, plectin, and WD repeat-containing protein 1 were upregulated, whereas thioredoxin 1 and spectrin alpha chain, nonerythrocytic 1 were downregulated. Across control, erythroplakia, and cancer, L-lactate dehydrogenase A chain was upregulated whereas aldehyde dehydrogenase 2, peroxiredoxin 1, heat shock 70 kDa protein 1B, and spectrin alpha chain, nonerythrocytic 1 were downregulated. We found that proteins involved in leukoplakia were associated with alteration in cytoskeletal disruption and glycolysis, while in erythroplakia, they were associated with alteration in response to oxidative stress and glycolysis across phenotypes. Hierarchical clustering subgrouped half of precancerous samples under the main branch of the control and the remaining half under carcinoma. Similarly, principal component analysis identified segregated clusters of control, precancerous lesions, and cancer, but erythroplakia phenotypes, in particular, overlapped more with the cancer cluster. Qualitative and quantitative protein signatures across control, precancer, and cancer phenotypes explain possible functional outcomes that dictate malignant transformation to oral carcinoma.

The hsa-miR-516a-5p and hsa-miR-516b-5p microRNAs reduce the migration and invasion on T98G glioblastoma cell line

microRNAs (miRNAs) are involved in numerous functions and processes in the brain and other organs through the regulation of gene and protein expression. miRNA dysregulation is associated with the development of several diseases, including the brain and Central Nervous System cancer (CNS). The hsa-miR-516a-5p and hsa-miR-516b-5p are involved in proliferation, migration, and invasion in different tumor models, but their antitumor effect has not been evaluated in cancer of CNS. Therefore, we aimed to assess the effect of the miRNAs hsa-miR-516a-5p and miRNA hsa-miR-516b-5p on the Glioblastoma cell line (T98G). We used synthetic miRNA mimics to induce the overexpression of both miRNAs in the cell line, which was corroborated by RT-qPCR. Next, we evaluated the effect on proliferation, migration, and invasion using the CyQuant direct kit, ThinCert ™ inserts and invasion BioCoat ™ Matrigel® Invasion Chambers. We found upregulation of these miRNAs induced significant changes on the migration and invasion processes of T98G cells, but not affected the proliferation rate. These results suggest that both microRNAs could be playing an important role in the control of tumor progression towards metastasis. The bioinformatics analysis showed that target genes for these miRNAs are involved in different biological processes such as in cell adhesion molecule binding and cell junction disassembly, which are important for cancer progression. Further studies and experimental validation are needed to identify the genes regulated by microRNAs.

Cytoskeletal and Cytoskeleton-Associated Proteins: Key Regulators of Cancer Stem Cell Properties

Cancer stem cells (CSCs) are a subpopulation of cancer cells possessing stemness characteristics that are closely associated with tumor proliferation, recurrence and resistance to therapy. Recent studies have shown that different cytoskeletal components and remodeling processes have a profound impact on the behavior of CSCs. In this review, we outline the different cytoskeletal components regulating the properties of CSCs and discuss current and ongoing therapeutic strategies targeting the cytoskeleton. Given the many challenges currently faced in targeted cancer therapy, a deeper comprehension of the molecular events involved in the interaction of the cytoskeleton and CSCs will help us identify more effective therapeutic strategies to eliminate CSCs and ultimately improve patient survival.

Identification of signaling pathways associated with achaete-scute homolog 1 in glioblastomas through ChIP-seq data bioinformatics

Background: Achaete-scute homolog 1 transcription factors were important in the differentiation of neuronal-like glioblastoma (GBM) cancer stem cells (CSCs). To gain a better understanding of the role of ASCL1 in GBM, chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) data can be analyzed to construct their gene transcription regulation network.

Methods: GSE87618 was downloaded from the Gene Expression Omnibus, which is a famous database, in the field of biology. The filtered clean reads were mapped to the human genome utilizing the software of bowtie2. Then, differential peak analysis was performed by diffbind. Finally, the annotated gene functions and signaling pathways were investigated by Gene ontology function and kyoto encyclopedia of genes genomes (KEGG) pathway enrichment analysis. Moreover, the protein–protein interaction network (PPI) analysis of genes obtained from ASCL1 was carried out to explore the hub genes influenced by ASCL1.

Results: A total of 516 differential peaks were selected. GO analysis of functions revealed that promoter, untranslated region (UTR), exon, intron, and intergenic genes were mainly enriched in biological pathways such as keratinization, regulation of cAMP metabolic process, blood coagulation, fibrin clot formation, midgut development, and synapse assembly. Genes were mainly enriched in KEGG pathways including pentose phosphate pathway, glycosphingolipid biosynthesis—globo and isoglobo series, ECM–receptor interaction, and adherens junction. In total, 244 nodes and 475 interaction pairs were included in the PPI network with the hub genes including EGFR, CTNNB1, and SPTAN1.

Conclusion: EGFR, SPTAN1, and CTNN1B might be the potential down-stream genes of ASCL1 in GBM development, and CTNN1B might make contributions to GBM progression on regulating the cAMP pathway.

Target-Based Small Molecule Drug Discovery for Colorectal Cancer: A Review of Molecular Pathways and In Silico Studies

Colorectal cancer is one of the most prevalent cancer types. Although there have been breakthroughs in its treatments, a better understanding of the molecular mechanisms and genetic involvement in colorectal cancer will have a substantial role in producing novel and targeted treatments with better safety profiles. In this review, the main molecular pathways and driver genes that are responsible for initiating and propagating the cascade of signaling molecules reaching carcinoma and the aggressive metastatic stages of colorectal cancer were presented. Protein kinases involved in colorectal cancer, as much as other cancers, have seen much focus and committed efforts due to their crucial role in subsidizing, inhibiting, or changing the disease course. Moreover, notable improvements in colorectal cancer treatments with in silico studies and the enhanced selectivity on specific macromolecular targets were discussed. Besides, the selective multi-target agents have been made easier by employing in silico methods in molecular de novo synthesis or target identification and drug repurposing.

High Expression of Casein Kinase 2 Alpha Is Responsible for Enhanced Phosphorylation of DNA Mismatch Repair Protein MLH1 and Increased Tumor Mutation Rates in Colorectal Cancer

Simple Summary

Colorectal cancer (CRC) is associated with DNA mismatch repair (MMR) deficiency. The serine/threonine casein kinase 2 alpha (CK2α) is able to phosphorylate and inhibit MMR protein MLH1 in vitro. This study aimed to analyze the relevance of CK2α for MLH1 phosphorylation in vivo. Around 50% of CRCs were identified to express significantly increased nuclear/cytoplasmic CK2α. High nuclear/cytoplasmic CK2α level could be significantly correlated with reduced 5-year survival outcome of patients, increased MLH1 phosphorylation, and enriched somatic tumor mutation rates. Overall, our study demonstrated, in vivo, that enhanced CK2α leads to an increase of MLH1 phosphorylation, higher tumor mutation rates, and is an unfavorable prognosis for patients.

Abstract

DNA mismatch repair (MMR) deficiency plays an essential role in the development of colorectal cancer (CRC). We recently demonstrated in vitro that the serine/threonine casein kinase 2 alpha (CK2α) causes phosphorylation of the MMR protein MLH1 at position serine 477, which significantly inhibits the MMR. In the present study, CK2α-dependent MLH1 phosphorylation was analyzed in vivo. Using a cohort of 165 patients, we identified 88 CRCs showing significantly increased nuclear/cytoplasmic CK2α expression, 28 tumors with high nuclear CK2α expression and 49 cases showing a general low CK2α expression. Patients with high nuclear/cytoplasmic CK2α expression demonstrated significantly reduced 5-year survival outcome. By immunoprecipitation and Western blot analysis, we showed that high nuclear/cytoplasmic CK2α expression significantly correlates with increased MLH1 phosphorylation and enriched somatic tumor mutation rates. The CK2α mRNA levels tended to be enhanced in high nuclear/cytoplasmic and high nuclear CK2α-expressing tumors. Furthermore, we identified various SNPs in the promotor region of CK2α, which might cause differential CK2α expression. In summary, we demonstrated that high nuclear/cytoplasmic CK2α expression in CRCs correlates with enhanced MLH1 phosphorylation in vivo and seems to be causative for increased mutation rates, presumably induced by reduced MMR. These observations could provide important new therapeutic targets.

MLH1 mediates cytoprotective nucleophagy to resist 5-Fluorouracil-induced cell death in colorectal carcinoma

Colorectal Cancer (CRC) with Microsatellite instability (MSI) and mutLhomolog-1 (MLH1) gene deficiency are less aggressive than MLH1 proficient cancers. MLH1 is involved in several cellular processes, but its connection with the autophagy-dependent cellular response towards anticancer drugs remains unclear. In this study, we aimed to investigate the interaction between MLH1 and the autophagy marker LC3, which facilitated nucleophagy induction, and its potential role in determining sensitivity to 5-Fluorouracil (5-FU) induced cell death. To examine the role of MLH1 in DNA-damage-induced nucleophagy in CRC cells, we utilized a panel of MLH1 deficient and MLH1 proficient CRC cell lines. We included a parental HCT116 cell line (MLH1-/-) and its isogenic cell line HCT116 MLH1+/- in which a single allele of the MLH1 gene was introduced using CRISPR-Cas9 gene editing. We observed that MLH1 proficient cells were less sensitive to the 5-FU-induced cytotoxic effect. The 5-FU induced DNA damage led to LC3 up-regulation, which was dependent on MLH1 overexpression. Moreover, immunofluorescence and immunoprecipitation data showed LC3 and MLH1 were colocalized in CRC cells. Consequently, MLH1 dependent 5-FU-induced DNA damage contributed to the formation of micronuclei. These micronuclei colocalize with autolysosome, indicating a cytoprotective role of MLH1 dependent nucleophagy. Interestingly, siRNA knockdown of MLH1 in HCT116 MLH1+/- prevented LC3 upregulation and micronuclei formation. These novel data are the first to show an essential role of MLH1 in mediating the chemoresistance and survival of cancer cells by increasing the LC3 expression and inducing nucleophagy in 5-FU treated CRC cells.

SPTAN1 Expression Predicts Treatment and Survival Outcomes in Colorectal Cancer

Simple Summary

Colorectal cancer (CRC) is a common and deadly form of cancer. Non-erythroid spectrin αII (SPTAN1), a protein of the cytoskeleton, is thought to be involved in CRC development and progression. In this study, we explore whether measuring SPTAN1 levels in resected CRC specimens might help to predict patient survival outcomes and response to chemotherapy. Indeed, we find that higher SPTAN1 protein and mRNA levels in CRC specimens associate with longer patient survival times. Using cell culture experiments, we then show that cells with lower SPTAN1 levels are less susceptible to FOLFOX chemotherapy, a standard treatment regimen for patients with CRC. Overall, our study underscores the importance of cytoskeletal proteins in shaping tumour biology and treatment responses and nominates SPTAN1 as a biomarker to improve patient stratification and refine therapeutic decisions in CRC.

Abstract

Colorectal cancer (CRC) is a leading cause of cancer-related morbidity and mortality. In a cohort of 189 patients with CRC, we recently showed that expression of the cytoskeletal scaffolding protein non-erythroid spectrin αII (SPTAN1) was lower in advanced metastatic tumours. The aim of the present study was to clarify the association of intratumoural SPTAN1 expression levels with treatment and survival outcomes in patients with CRC. The analysis was based on histologic assessment of SPTAN1 protein levels in our own CRC cohort, and transcriptome data of 573 CRC cases from The Cancer Genome Atlas (TCGA). We first establish that high intratumoural levels of SPTAN1 protein and mRNA associate with favourable survival outcomes in patients with CRC. Next, a response prediction signature applied to the TCGA data reveals a possible link between high SPTAN1 transcript levels and improved patient responses to FOLFOX chemotherapy. Complementary in vitro experiments confirm that SPTAN1 knockdown strains of the colon cancer cell lines HT-29, HCT116 mlh1-2 and Caco-2 are less responsive to FOLFOX chemotherapy compared with SPTAN1-proficient control strains. Taken together, we identify SPTAN1 as a novel prognostic biomarker in CRC and show that SPTAN1 expression levels may predict patient responses to chemotherapy. These investigations illustrate how an affordable, histology-based diagnostic test could directly impact therapeutic decision-making at the bedside.

Oxymatrine Synergistically Enhances Doxorubicin Anticancer Effects in Colorectal Cancer

The combination of chemotherapy with natural products is a common strategy to enhance anticancer effects while alleviating the dose-dependent adverse effects of cancer treatment. Oxymatrine (OMT) has been extensively reported as having anticancer activity. Doxorubicin (DOX) is a chemotherapeutic DNA-damaging agent used for the treatment of carcinoma. In this study, we investigated whether synergistic effects exist with the combination treatment with OMT and DOX using human colorectal cancer cell (CRC) lines and the potential mechanisms involved in in vitro and in vivo activities. The MTT and colony formation assay results showed that compared to either OMT or DOX monotherapy, the combination of OMT + DOX markedly inhibited the growth of HT-29 and SW620 cells. Wound healing assays showed significant inhibition of cell migration with co-treatment, supported by the change in E-cadherin and N-cadherin expressions in Western blotting. Furthermore, flow cytometry analysis revealed that OMT + DOX co-treatment enhanced cell apoptosis as a result of ROS generation, whereas NAC attenuated OMT + DOX–induced apoptosis. Similarly, the apoptosis-related proteins (cleaved caspase-3, cleaved caspase-9, and the ratio of Bax/Bcl-2) were determined by Western blotting, which showed that the expressions of these markers were notably increased in the co-treatment group. Furthermore, co-administration of a low dose of DOX and OMT inhibited xenograft tumor growth in a dose-dependent manner. TUNEL assay and Ki67 staining images indicated more apoptosis and less proliferation occurred in OMT plus DOX-treated xenograft tumors. Meanwhile, the combination strategy decreased cardiotoxicity, which is the most serious side effect of DOX. RNA sequencing was performed to explore the precise molecular alterations involved in the combination group. Among the numerous differentially expressed genes, downregulated FHL-2 and upregulated cleaved SPTAN1 were validated in both mRNA and protein levels of HT-29 and SW620 cells. These two proteins might play a pivotal role involving in OMT + DOX synergistic activity. Overall, OMT in combination with DOX presented an outstanding synergistic antitumor effect, indicating that this beneficial combination may offer a potential therapy for CRC patients.

Identification of differentially expressed proteins in the locoregional recurrent esophageal squamous cell carcinoma by quantitative proteomics

Background

This study aimed to identify potential biomarkers associated with locoregional recurrence in patients with esophageal squamous cell carcinoma (ESCC) after radical resection.

Methods

We performed a quantitative proteomics analysis using isobaric tags for relative and absolute quantification (iTRAQ) with reversed-phase liquid chromatography-mass spectrometry (RPLC-MS) to identify differential expression proteins (DEPs) between a locoregional recurrence group and good prognosis group of ESCC after radical esophagectomy. The bioinformatics analysis was performed with ingenuity pathway analysis software (IPA) and Gene Ontology (GO) database using the software of MAS 3.0. Kaplan-Meier (KM) Plotter Online Tool (http://www.kmplot.com) was used to evaluate the relationship between the differential expression of proteins and survival in patients with ESCC.

Results

More than 400 proteins were quantitated of which 27 proteins had upregulated expression and 55 proteins had downregulated expression in the locoregional recurrence group compared to the good prognosis group. These 82 DEPs were associated with biological procession of cancer development including cellular movement, cellular assembly and organization, cellular function and maintenance, cellular growth and proliferation, cell death and survival, DNA replication recombination and repair, and so on. Of these DEPs, SPTAN1 and AGT proteins were identified to be associated with RFS in ESCC. SPTAN1 was positively associated with RFS and AGT was negatively associated with RFS. Expression of SPTAN1 tended to have favorable OS while expression of AGT tended to have poor OS.

Conclusions

Our results demonstrated that quantitative proteomics is an effective discovery tool to identify biomarkers for prognosis prediction in ESCC. However, it needs more studies with large populations of ESCC to validate these potential biomarkers.

The Clinical Significance and Potential Molecular Mechanism of PTTG1 in Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is the major histological type of esophageal cancers worldwide. Transcription factor PTTG1 was seen highly expressed in a variety of tumors and was related to the degree of tumor differentiation, invasion, and metastasis. However, the clinical significance of PTTG1 had yet to be verified, and the mechanism of abnormal PTTG1 expression in ESCC was not clear. In this study, the comprehensive analysis and evaluation of PTTG1 expression in ESCC were completed by synthesizing in-house immunohistochemistry (IHC), clinical sample tissue RNA-seq (in-house RNA-seq), public high-throughput data, and literature data. We also explored the possible signaling pathways and target genes of PTTG1 in ESCC by combining the target genes of PTTG1 (displayed by ChIP-seq), differentially expressed genes (DEGs) of ESCC, and PTTG1-related genes, revealing the potential molecular mechanism of PTTG1 in ESCC. In the present study, PTTG1 protein and mRNA expression levels in ESCC tissues were all significantly higher than in non-cancerous tissues. The pool standard mean difference (SMD) of the overall PTTG1 expression was 1.17 (95% CI: 0.72-1.62, P < 0.01), and the area under curve (AUC) of the summary receiver operating characteristic (SROC) was 0.86 (95% CI: 0.83-0.89). By combining the target genes displayed by ChIP-seq of PTTG1, DEGs of ESCC, and PTTG1-related genes, it was observed that PTTG1 may interact with these genes through chemokines and cytokine signaling pathways. By constructing a protein-protein interaction (PPI) network and combining ChIP-seq data, we obtained four PTTG1 potential target genes, SPTAN1, SLC25A17, IKBKB, and ERH. The gene expression of PTTG1 had a strong positive correlation with SLC25A17 and ERH, which suggested that PTTG1 might positively regulate the expression of these two genes. In summary, the high expression of PTTG1 may play an important role in the formation of ESCC. These roles may be completed by PTTG1 regulating the downstream target genes SLC25A17 and ERH.

E-cig vapor condensate alters proteome and lipid profiles of membrane rafts: impact on inflammatory responses in A549 cells

Electronic cigarettes (e-cigs) are battery-operated heating devices that aerosolize e-liquid, typically containing nicotine and several other chemicals, which is then inhaled by a user. Over the past decade, e-cigs have gained immense popularity among both smokers and non-smokers. One reason for this is that they are advertised as a safe alternative to conventional cigarettes. However, the recent reports of e-cig use associated lung injury have ignited a considerable debate about the relative harm and benefits of e-cigs. The number of reports about e-cig-induced inflammation and pulmonary health is increasing as researchers seek to better understand the effects of vaping on human health. In line with this, we investigated the molecular events responsible for the e-cig vapor condensate (ECVC)-mediated inflammation in human lung adenocarcinoma type II epithelial cells (A549). In an attempt to limit the variables caused by longer ingredient lists of flavored e-cigs, tobacco-flavored ECVC (TF-ECVC±nicotine) was employed for this study. Interestingly, we observed significant upregulation of cytokines and chemokines (IL-6, IL-8, and MCP-1) in A549 cells following a 48 h TF-ECVC challenge. Furthermore, there was a significant increase in the expression of pattern recognition receptors TLR-4 and NOD-1, lipid raft-associated protein caveolin-1, and transcription factor NF-кB in TF-ECVC with and/or without nicotine-challenged lung epithelial cells. Our results further demonstrate the harboring of TLR-4 and NOD-1 in the caveolae of TF-ECVC-challenged A549 cells. Proteomic and lipidomic analyses of lipid raft fractions from control and challenged cells revealed a distinct protein and lipid profile in TF-ECVC (w/wo nicotine)-exposed A549 cells. Interestingly, the inflammatory effects of TF-ECVC (w/wo nicotine) were inhibited following the caveolin-1 knockdown, thus demonstrating a critical role of caveolae raft-mediated signaling in eliciting inflammatory responses upon TF-ECVC challenge. Graphical Abstract Graphical Abstract.

Cytoskeletal Remodeling in Cancer

Simple Summary

Cell migration is an essential process from embryogenesis to cell death. This is tightly regulated by numerous proteins that help in proper functioning of the cell. In diseases like cancer, this process is deregulated and helps in the dissemination of tumor cells from the primary site to secondary sites initiating the process of metastasis. For metastasis to be efficient, cytoskeletal components like actin, myosin, and intermediate filaments and their associated proteins should co-ordinate in an orderly fashion leading to the formation of many cellular protrusions-like lamellipodia and filopodia and invadopodia. Knowledge of this process is the key to control metastasis of cancer cells that leads to death in 90% of the patients. The focus of this review is giving an overall understanding of these process, concentrating on the changes in protein association and regulation and how the tumor cells use it to their advantage. Since the expression of cytoskeletal proteins can be directly related to the degree of malignancy, knowledge about these proteins will provide powerful tools to improve both cancer prognosis and treatment.

Abstract

Successful metastasis depends on cell invasion, migration, host immune escape, extravasation, and angiogenesis. The process of cell invasion and migration relies on the dynamic changes taking place in the cytoskeletal components; actin, tubulin and intermediate filaments. This is possible due to the plasticity of the cytoskeleton and coordinated action of all the three, is crucial for the process of metastasis from the primary site. Changes in cellular architecture by internal clues will affect the cell functions leading to the formation of different protrusions like lamellipodia, filopodia, and invadopodia that help in cell migration eventually leading to metastasis, which is life threatening than the formation of neoplasms. Understanding the signaling mechanisms involved, will give a better insight of the changes during metastasis, which will eventually help targeting proteins for treatment resulting in reduced mortality and longer survival.

SH3BGRL2 exerts a dual function in breast cancer growth and metastasis and is regulated by TGF-β1

SH3 domain-binding glutamic acid-rich-like protein 2 (SH3BGRL2) is a poorly defined member of the SH3BGR gene family with potential roles in cell differentiation and tissue development. Here, we report for the first time that SH3BGRL2 exerts a dual function in breast tumor growth and metastasis. SH3BGRL2 was downregulated in a subset of primary breast tumors, and suppressed breast cancer cell proliferation and colony formation in vitro and xenograft tumor growth in vivo. Strikingly, SH3BGRL2 enhanced breast cancer cell migratory, invasive, and lung metastatic capacity. Mechanistic investigations revealed that SH3BGRL2 interacted with and transcriptionally repressed spectrin alpha, non-erythrocytic 1 (SPTAN1) and spectrin beta, non-erythrocytic 1 (SPTBN1), two important cytoskeletal proteins. Functional rescue assays further demonstrated that depletion of SH3BGRL2 reduced breast cancer cell invasive potential, which was partially rescued by knockdown of SPTAN1 and SPTBN1 using specific small interfering RNA. Moreover, transforming growth factor-β1 (TGF-β1) transcriptionally activated SH3BGRL2 expression in breast cancer cells through the canonical TGF-β receptor-Smad pathway. Collectively, these results establish a dual function of SH3BGRL2 in breast cancer growth and metastasis and uncover SH3BGRL2 as a downstream target of the TGF-β1 signaling pathway in breast cancer cells.

Expression and secretion of the pro‑inflammatory cytokine IL‑8 is increased in colorectal cancer cells following the knockdown of non‑erythroid spectrin αII

Non‑erythroid spectrin αII (SPTAN1) expression is decreased in ~40% of cases of MLH1‑deficient colorectal cancer (CRC). SPTAN1 knockdown reduces cell viability, cellular mobility and cell‑cell contact formation, indicating that the SPTAN1 plays an important role in tumour growth, attachment and in regulating the tumour microenvironment. Changes in the tumour microenvironment can affect the immune response. Therefore, in the present study, proteome arrays were used to analyse the expression of 119 different chemokines and soluble receptors in CRC cell lines in which mutL homologue 1 (MLH1) or SPTAN1 were knocked down. The levels of interleukin (IL)‑8 were significantly increased in the cells in which SPTAN1 was knocked down, both at the mRNA and protein level. ELISA demonstrated that the cells in which SPTAN1 was knocked down secreted increased quantities of IL‑8, and chemotaxis assays revealed the enhanced trafficking of neutrophils, which was induced by media containing higher levels of IL‑8. The IL‑8 receptors, CRCX1 and CRCX2, were expressed in all the cell lines examined; however, their expression was not directly associated with IL‑8 expression. The results of the present study thus demonstrated that CRC cells in which SPTAN1 was knocked down secreted significantly higher levels of IL‑8, which in‑turn increased the migration of neutrophilic granulocytes. As MLH1‑deficient CRC exhibits an increased infiltration of cytotoxic T‑cells and is associated with a decreased SPTAN1 expression, it can thus be hypothesized that CRC with a low SPTAN1 expression may release increased quantities of IL‑8, resulting in increased immune cell infiltration.

The functional importance of lamins, actin, myosin, spectrin and the LINC complex in DNA repair

Three major proteins in the nucleoskeleton, lamins, actin, and spectrin, play essential roles in maintenance of nuclear architecture and the integrity of the nuclear envelope, in mechanotransduction and mechanical coupling between the nucleoskeleton and cytoskeleton, and in nuclear functions such as regulation of gene expression, transcription and DNA replication. Less well known, but critically important, are the role these proteins play in DNA repair. The A-type and B-type lamins, nuclear actin and myosin, spectrin and the LINC (linker of nucleoskeleton and cytoskeleton) complex each function in repair of DNA damage utilizing various repair pathways. The lamins play a role in repair of DNA double-strand breaks (DSBs) by nonhomologous end joining (NHEJ) or homologous recombination (HR). Actin is involved in repair of DNA DSBs and interacts with myosin in facilitating relocalization of these DSBs in heterochromatin for HR repair. Nonerythroid alpha spectrin (αSpII) plays a critical role in repair of DNA interstrand cross-links (ICLs) where it acts as a scaffold in recruitment of repair proteins to sites of damage and is important in the initial damage recognition and incision steps of the repair process. The LINC complex contributes to the repair of DNA DSBs and ICLs. This review will address the important functions of these proteins in the DNA repair process, their mechanism of action, and the profound impact a defect or deficiency in these proteins has on cellular function. The critical roles of these proteins in DNA repair will be further emphasized by discussing the human disorders and the pathophysiological changes that result from or are related to deficiencies in these proteins. The demonstrated function for each of these proteins in the DNA repair process clearly indicates that there is another level of complexity that must be considered when mechanistically examining factors crucial for DNA repair.

Impact statement

Proteins in the nucleoskeleton, lamins, actin, myosin, and spectrin, have been shown to play critical roles in DNA repair. Deficiencies in these proteins are associated with a number of disorders. This review highlights the role these proteins and their association with the LINC complex play in DNA repair processes, their mechanism of action and the impacts deficiencies in these proteins have on DNA repair and on disorders associated with a deficiency in these proteins. It will clarify how these proteins, which interact with “classic DNA repair proteins” (e.g., RAD51, XPF), represent another level of complexity in the DNA repair process, which must be taken into consideration when carrying out mechanistic studies on proteins involved in DNA repair and in developing models for DNA repair pathways. This knowledge is essential for determining how deficiencies in these proteins relate to disorders resulting from loss of functional activity of these proteins.

Five genes may predict metastasis in non-small cell lung cancer using bioinformatics analysis

Lung cancer is one of the most common types of malignancy worldwide. The prognosis of lung cancer is poor, due to the onset of metastases. The aim of the present study was to examine lung cancer metastasis-associated genes. To identify novel metastasis-associated targets, our previous study detected the differentially expressed mRNAs and long non-coding RNAs between the large-cell lung cancer high-metastatic 95D cell line and the low-metastatic 95C cell line by microarray assay. In the present study, these differentially expressed genes (DEGs) were analyzed via bioinformatics methods, including Gene Ontology functional analysis and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. A protein-protein interaction network was subsequently constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins online database and Cytoscape software, and 17 hub genes were screened out on the basis of connectivity degree. These hub genes were further validated in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) using the online Gene Expression Profiling Interactive Analysis database. A total of seven hub genes were identified to be significantly differentially expressed in LUAD and LUSC. The prognostic information was detected using Kaplan-Meier plotter. As a result, five genes were revealed to be closely associated with the overall survival time of patients with lung cancer, including phosphoinositide-3-kinase regulatory subunit 1, FYN, thrombospondin 1, nonerythrocytic α-spectrin 1 and secreted phosphoprotein 1. In addition, lung cancer and adjacent lung tissue samples were used to validate these hub genes by reverse transcription-quantitative polymerase chain reaction. In conclusion, the results of the present study may provide novel metastasis-associated therapeutic strategies or potential biomarkers in non-small cell lung cancer.

The Role of Nonerythroid Spectrin αII in Cancer

Nonerythroid spectrin αII (SPTAN1) is an important cytoskeletal protein that ensures vital cellular properties including polarity and cell stabilization. In addition, it is involved in cell adhesion, cell-cell contact, and apoptosis. The detection of altered expression of SPTAN1 in tumors indicates that SPTAN1 might be involved in the development and progression of cancer. SPTAN1 has been described in cancer and therapy response and proposed as a potential marker protein for neoplasia, tumor aggressiveness, and therapeutic efficiency. On one hand, the existing data suggest that overexpression of SPTAN1 in tumor cells reflects neoplastic and tumor promoting activity. On the other hand, nuclear SPTAN1 can have tumor suppressing effects by enabling DNA repair through interaction with DNA repair proteins. Moreover, SPTAN1 cleavage products occur during apoptosis and could serve as markers for the efficacy of cancer therapy. Due to SPTAN1's multifaceted functions and its role in adhesion and migration, SPTAN1 can influence tumor growth and progression in both positive and negative directions depending on its specific regulation. This review summarizes the current knowledge on SPTAN1 in cancer and depicts several mechanisms by which SPTAN1 could impact tumor development and aggressiveness.