Sam68 expression and cytoplasmic localization is correlated with lymph node metastasis as well as prognosis in patients with early-stage cervical cancer

An in vitro CRISPR screen of cell-free DNA identifies apoptosis as the primary mediator of cell-free DNA release

ABTRACT

Clinical circulating cell-free DNA (cfDNA) testing is now routine, however test accuracy remains limited. By understanding the life-cycle of cfDNA, we might identify opportunities to increase test performance. Here, we profile cfDNA release across a 24-cell line panel and utilize a cell-free CRISPR screen (cfCRISPR) to identify mediators of cfDNA release. Our panel outlines two distinct groups of cell lines: one which releases cfDNA fragmented similarly to clinical samples and purported as characteristic of apoptosis, and another which releases larger fragments associated with vesicular or necrotic DNA. Our cfCRISPR screens reveal that genes mediating cfDNA release are primarily involved with apoptosis, but also identify other subsets of genes such as RNA binding proteins as potential regulators of cfDNA release. We observe that both groups of cells lines identified primarily produce cfDNA through apoptosis. These results establish the utility of cfCRISPR, genetically validate apoptosis as a major mediator of DNA release in vitro, and implicate ways to improve cfDNA assays.

Sam68 is a druggable vulnerability point in cancer stem cells

Sam68 (Src associated in mitosis of 68 kDa) is an RNA-binding and multifunctional protein extensively characterized in numerous cellular functions, such as RNA processing, cell cycle regulation, kinase- and growth factor signaling. Recent investigations highlighted Sam68 as a primary target of a class of reverse-turn peptidomimetic drugs, initially developed as inhibitors of Wnt/β-catenin mediated transcription. Further investigations on such compounds revealed their capacity to selectively eliminate cancer stem cell (CSC) activity upon engaging Sam68. This work highlighted previously unappreciated roles for Sam68 in the maintenance of neoplastic self-renewal and tumor-initiating functions. Here, we discuss the implication of Sam68 in tumorigenesis, where central findings support its contribution to chromatin regulation processes essential to CSCs. We also review advances in CSC-targeting drug discovery aiming to modulate Sam68 cellular distribution and protein-protein interactions. Ultimately, Sam68 constitutes a vulnerability point of CSCs and an attractive therapeutic target to impede neoplastic stemness in human tumors.

Multidimensional outlook on the pathophysiology of cervical cancer invasion and metastasis

Cervical cancer being one of the primary causes of high mortality rates among women is an area of concern, especially with ineffective treatment strategies. Extensive studies are carried out to understand various aspects of cervical cancer initiation, development and progression; however, invasive cervical squamous cell carcinoma has poor outcomes. Moreover, the advanced stages of cervical cancer may involve lymphatic circulation with a high risk of tumor recurrence at distant metastatic sites. Dysregulation of the cervical microbiome by human papillomavirus (HPV) together with immune response modulation and the occurrence of novel mutations that trigger genomic instability causes malignant transformation at the cervix. In this review, we focus on the major risk factors as well as the functionally altered signaling pathways promoting the transformation of cervical intraepithelial neoplasia into invasive squamous cell carcinoma. We further elucidate genetic and epigenetic variations to highlight the complexity of causal factors of cervical cancer as well as the metastatic potential due to the changes in immune response, epigenetic regulation, DNA repair capacity, and cell cycle progression. Our bioinformatics analysis on metastatic and non-metastatic cervical cancer datasets identified various significantly and differentially expressed genes as well as the downregulation of potential tumor suppressor microRNA miR-28-5p. Thus, a comprehensive understanding of the genomic landscape in invasive and metastatic cervical cancer will help in stratifying the patient groups and designing potential therapeutic strategies.

Splicing factor SRSF3 promotes the progression of cervical cancer through regulating DDX5

Aberrant alternative splicing (AS) profoundly affects tumorigenesis and cancer progression. Serine/arginine-rich splicing factor 3 (SRSF3) regulates the AS of precursor mRNAs and acts as a proto-oncogene in many tumors, but its function and potential mechanisms in cervical cancer remain unclear. Here, we found that SRSF3 was highly expressed in cervical cancer tissues and that SRSF3 expression was correlated with prognosis after analyses of the The Cancer Genome Atlas and GEO databases. Furthermore, knockdown of SRSF3 reduced the proliferation, migration, and invasion abilities of HeLa cells, while overexpression of SRSF3 promoted proliferation, migration, and invasion of CaSki cells. Further studies showed that SRSF3 mediated the variable splicing of exon 12 of the transcriptional cofactor DEAD-box helicase 5 (DDX5). Specifically, overexpression of SRSF3 promoted the production of the pro-oncogenic spliceosome DDX5-L and repressed the production of the repressive spliceosome DDX5-S. Ultimately, both SRSF3 and DDX5-L were able to upregulate oncogenic AKT expression, while DDX5-S downregulated AKT expression. In conclusion, we found that SRSF3 increased the production of DDX5-L and decreased the production of DDX5-S by regulating the variable splicing of DDX5. This, in turn promoted the proliferation, migration, and invasion of cervical cancer by upregulating the expression level of AKT. These results reveal the oncogenic role of SRSF3 in cervical cancer and emphasize the importance of the SRSF3-DDX5-AKT axis in tumorigenesis. SRSF3 and DDX5 are new potential biomarkers and therapeutic targets for cervical cancer.

Non-Coding RNAs of Extracellular Vesicles: Key Players in Organ-Specific Metastasis and Clinical Implications

Extracellular vesicles (EVs) are heterogeneous membrane-encapsulated vesicles released by most cells. They act as multifunctional regulators of intercellular communication by delivering bioactive molecules, including non-coding RNAs (ncRNAs). Metastasis is a major cause of cancer-related death. Most cancer cells disseminate and colonize a specific target organ via EVs, a process known as "organ-specific metastasis". Mounting evidence has shown that EVs are enriched with ncRNAs, and various EV-ncRNAs derived from tumor cells influence organ-specific metastasis via different mechanisms. Due to the tissue-specific expression of EV-ncRNAs, they could be used as potential biomarkers and therapeutic targets for the treatment of tumor metastasis in various types of cancer. In this review, we have discussed the underlying mechanisms of EV-delivered ncRNAs in the most common organ-specific metastases of liver, bone, lung, brain, and lymph nodes. Moreover, we summarize the potential clinical applications of EV-ncRNAs in organ-specific metastasis to fill the gap between benches and bedsides.

RNA-binding proteins: Underestimated contributors in tumorigenesis

mRNA export, translation, splicing, cleavage or capping determine mRNA stability, which represents one of the primary aspects regulating gene expression and function. RNA-binding proteins (RBPs) bind to their target mRNAs to regulate multiple cell functions by increasing or reducing their stability. In recent decades, studies of the role of RBPs in tumorigenesis have revealed an increasing number of proteins impacting the prognosis, diagnosis and cancer treatment. Several RBPs have been identified based on their interactions with oncogenes or tumor suppressor genes in human cancers, which are involved in apoptosis, the epithelial-mesenchymal transition (EMT), DNA repair, autophagy, cell proliferation, immune response, metabolism, and the regulation of noncoding RNAs. In this review, we propose a model showing how RBP mutations influence tumorigenesis, and we update the current knowledge regarding the molecular mechanism by which RBPs regulate cancer. Special attention is being devoted to RBPs that represent prognostic and diagnostic factors in cancer patients.

High expression of Sam68 contributes to metastasis by regulating vimentin expression and a motile phenotype in oral squamous cell carcinoma

The present study aimed to investigate the clinical and biological significance of Src-associated in mitosis 68 kDa (Sam68) in oral squamous cell carcinoma (OSCC). Immunohistochemical analysis was performed on tissue samples obtained from 77 patients with OSCC. Univariate analysis revealed that the high expression of Sam68 was significantly correlated with advanced pathological T stage (P=0.01), positive lymphovascular invasion (P=0.01), and pathological cervical lymph node metastasis (P<0.01). Moreover, multivariate analysis demonstrated that the high expression of Sam68 was an independent predictive factor for cervical lymph node metastasis (odds ratio, 4.39; 95% confidence interval, 1.49-14.23; P<0.01). These results indicated that high Sam68 expression contributed to tumor progression, especially cervical lymph node metastasis, in OSCC. mRNA sequencing was also performed to assess the changes in the transcriptome between OSCC cells with Sam68 knockdown and control cells with the aim of elucidating the biological roles of Sam68. Gene Ontology enrichment analysis revealed that downregulated differentially expressed genes (DEGs) were concentrated in some biological processes related to epithelial-mesenchymal transition. Among these DEGs, it was established that vimentin was particularly downregulated in these cells. It was also confirmed that Sam68 knockdown reduced the motility of OSCC cells. Furthermore, the immunohistochemical study of vimentin identified the association between vimentin expression and Sam68 expression as well as cervical lymph node metastasis. In conclusion, the present study suggested that the high expression of Sam68 may contribute to metastasis by regulating vimentin expression and a motile mesenchymal phenotype in OSCC.

Role of Sam68 in Sunitinib induced renal cell carcinoma apoptosis

Sunitinib is one of the first‐line targeted drugs for metastatic renal cell carcinoma (RCC) with dual effects of antiangiogensis and proapoptosis. Sam68 (Src‐associated in mitosis, 68 KDa), is found being involved in cell apoptosis. This article reveals that Sam68 impacts the sensitivity to sunitinib by mediating the apoptosis of RCC cells. Immunohistochemical staining indicated that the Sam68 expression levels in sunitinib sensitive tumor tissues were markedly higher than those in sunitinib resistant tumor tissues. Sunitinib induced RCC cell apoptosis in a concentration‐dependent manner and inhibited the expression of total and phosphorylated Sam68 (p‐Sam68). Downregulation of Sam68 expression inhibited RCC cell apoptosis induced by sunitinib. While upregulation of Sam68 expression could enhance apoptosis induced by sunitinib. Xenograft models showed that tumors in the Sam68‐knockdown group did not shrink as much as those in the control group after treatment with sunitinib for 4 weeks. Together, our results suggest that Sam68 expression is associated with the sensitivity of ccRCC patients to sunitinib. Sam68 may promote cell apoptosis induced by sunitinib, and the Sam68 expression level may be a biomarker for predicting sunitinib sensitivity in ccRCC patients.

Comparative O-GlcNAc Proteomic Analysis Reveals a Role of O-GlcNAcylated SAM68 in Lung Cancer Aggressiveness

Simple Summary

Lung cancer claims the most lives annually among cancers; to date, invasion and metastasis still pose challenges to effective treatment. O-GlcNAcylation, an enzymatic modification of proteins after biosynthesis, modulates the functions of many proteins. Aberrant O-GlcNAcylation is linked to pathogenic mechanisms of cancer, including invasion and metastasis. However, little is known about the profile of O-GlcNAcylated proteins involved in cancer aggressiveness. Here, by comparing profiles of O-GlcNAcylated proteins from two lung cancer cell lines different in their invasive potential, we identified candidates for O-GlcNAcylated proteins that may be involved in cancer aggressiveness. One of these candidates, SAM68, was further characterized. Results confirmed O-GlcNAcylation of SAM68; functional analyses on SAM68 with mutations at O-GlcNAcylation sites suggested a role of O-GlcNAcylated SAM68 in modulating lung cancer cell migration/invasion. Future elucidation of the functional significance of differential O-GlcNAcylation of proteins identified in this study may provide new insights into mechanisms of lung cancer progression.

Abstract

O-GlcNAcylation is a reversible and dynamic post-translational protein modification catalyzed by O-GlcNAc transferase (OGT). Despite the reported association of O-GlcNAcylation with cancer metastasis, the O-GlcNAc proteome profile for cancer aggressiveness remains largely uncharacterized. Here, we report our comparative O-GlcNAc proteome profiling of two differentially invasive lung adenocarcinoma cell lines, which identified 158 down-regulated and 106 up-regulated candidates in highly invasive cells. Among these differential proteins, a nuclear RNA-binding protein, SAM68 (SRC associated in mitosis of 68 kDa), was further investigated. Results showed that SAM68 is O-GlcNAcylated and may interact with OGT in the nucleus. Eleven O-GlcNAcylation sites were identified, and data from mutant analysis suggested that multiple serine residues in the N-terminal region are important for O-GlcNAcylation and the function of SAM68 in modulating cancer cell migration and invasion. Analysis of clinical specimens found that high SAM68 expression was associated with late cancer stages, and patients with high-OGT/high-SAM68 expression in their tumors had poorer overall survival compared to those with low-OGT/low-SAM68 expression. Our study revealed an invasiveness-associated O-GlcNAc proteome profile and connected O-GlcNAcylated SAM68 to lung cancer aggressiveness.

Non-histone methylation of SET7/9 and its biological functions

BACKGROUND

(su(var)-3-9,enhancer-of-zeste,trithorax) domain-containing protein 7/9 (SET7/9) is a member of the protein lysine methyltransferases (PLMTs or PKMTs) family. It contains a SET domain. Recent studies demonstrate that SET7/9 methylates both lysine 4 of histone 3 (H3-K4) and lysine(s) of non-histone proteins, including transcription factors, tumor suppressors, and membrane-associated receptors.

OBJECTIVE

This article mainly reviews the non-histone methylation effects of SET7/9 and its functions in tumorigenesis and development.

METHODS

PubMed was screened for this information.

RESULTS

SET7/9 plays a key regulatory role in various biological processes such as cell proliferation, transcription regulation, cell cycle, protein stability, cardiac morphogenesis, and development. In addition, SET7/9 is involved in the pathogenesis of hair loss, breast cancer progression, human carotid plaque atherosclerosis, chronic kidney disease, diabetes, obesity, ovarian cancer, prostate cancer, hepatocellular carcinoma, and pulmonary fibrosis.

CONCLUSION

SET7/9 is an important methyltransferase, which can catalyze the methylation of a variety of proteins. Its substrates are closely related to the occurrence and development of tumors.

CHN1 promotes epithelial-mesenchymal transition via the Akt/GSK-3β/Snail pathway in cervical carcinoma

Background

Metastasis and invasion are crucial in determining the mortality of cervical carcinoma (CC) patients. The epithelial–mesenchymal transition (EMT) is now a universal explanation for the mechanisms of tumor metastasis. Α-chimeric protein (α-chimaerin, CHN1) plays an important role in the regulation of signal transduction and development. However, the molecular regulatory relationships between CHN1 and CC progression in relation to EMT have not yet been identified.

Methods

The expression of CHN1 in CC tissues, adjacent tissues, and lymph node metastases from CC patients was detected by immunohistochemistry. Upregulation and knockdown of CHN1 were achieved by transfection of CC cells. The effect of CHN1 on cell proliferation was determined by CCK-8 and plate clone formation assays. Changes in migration and invasion capabilities were evaluated using scratch migration and transwell invasion assays. The effect of CHN1 overexpression and interference on xenograft tumor growth was determined by tumor weight and pathological analyses. The expression of EMT-related mRNAs was measured by qRT-PCR in transfected CC cells. EMT-related proteins and Akt/GSK-3β/Snail signaling pathway-related proteins were also evaluated by western blotting.

Results

CHN1 was overexpressed in CC tissues and was associated with lymph node metastasis and low survival in CC patients. Overexpression of CHN1 promoted cell proliferation, migration, and invasion in CC cells. In contrast, silencing of CHN1 inhibited these phenomena. Overexpression of CHN1 promoted tumor formation in an in vivo xenograft tumor mouse model, with increased tumor volumes and weights. In addition, CHN1 induced the expression of EMT-related transcription factors, accompanied by the decreased expression of epithelial markers and increased expression of mesenchymal markers. The Akt/GSK-3β/Snail signaling pathway was activated by overexpression of CHN1 in vitro, and activation of this pathway was inhibited by the signaling pathway inhibitor LY294002.

Conclusion

These results suggest that CHN1 promotes the development and progression of cervical carcinoma via the Akt/GSK-3β/Snail pathway by inducing EMT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02963-7.

The Function and Prognostic Value of RNA-Binding Proteins in Colorectal Adenocarcinoma Were Analyzed Based on Bioinformatics of Smart Medical Big Data

Colon cancer is the third most frequent cancer in the world and is mainly adenocarcinoma in terms of pathological type. It has been confirmed that the dysregulation of RNA-binding proteins (RBPs) significantly participates in the occurrence and development of numerous malignant tumors. Therefore, we analyzed the RBPs associated with colon adenocarcinoma (COAD) to assess their possible biological effects and prognostic value. A total of 398 COAD tissue datasets and 39 normal tissue datasets were retrieved from the TCGA data resource and screened out the RBPs, which are differentially expressed between tumor tissues and nontumor tissues. Then, bioinformatics analyses based on smart medical big data were conducted on these RBPs. Overall, 181 differentially expressed RBPs were uncovered, consisting of 121 upregulated RBPs and 60 downregulated RBPs. Finally, we selected 7 prognostic-related RBPs with research prospects and constructed a prognostic model according to the median risk score. There were remarkable differences in OS between the high-risk and low-risk groups. In addition, the performance of the prognostic model was evaluated and verified with other COAD patient data in the TCGA database. The results showed that the area under the ROC curve (AUC) for the train group was 0.744 and the one for the test group was 0.661, confirming that the model assesses patients' prognosis to some extent. And based on 7 hub RBPs, we constructed a nomogram as a reference for evaluating the survival rate of COAD patients.

LncRNA HOXA-AS2 Activates the Notch Pathway to Promote Cervical Cancer Cell Proliferation and Migration

Long non-coding RNAs (lncRNAs) are crucial participants in cancer development. HOXA cluster antisense RNA 2 (HOXA-AS2) plays a tumor promoter role in bladder cancer. However, the functional role of HOXA-AS2 in cervical cancer remains unclear. Our study first found that HOXA-AS2 expression was up-regulated in cervical cancer cells. Then functional analysis including cell counting kit-8 (CCK-8), colony formation, transwell, and wound healing uncovered that reduction of HOXA-AS2 remarkably impeded cell proliferation and migration in cervical cancer. Additionally, luciferase reporter assays were performed to confirm that HOXA-AS2 activated Notch signaling pathway via the mediation of independent recombination signal binding protein for JK (RBP-JK) activity. As we know, Notch intracellular domain (NICD) is associated with RBP-JK in the nucleus to promote target genes in the Notch pathway. Through RNA immunoprecipitation (RIP), RNA pull down, and fluorescent in situ hybridization (FISH) assays, we observed that HOXA-AS2 combined with NICD. Moreover, the data from Co-IP assays indicated that HOXA-AS2 reduction weakened the interaction of NICD and RBP-JK. Collectively, HOXA-AS2 played a cancer-promoting role in cervical cancer development by modulating the Notch pathway, which might become a novel target for cervical cancer treatment.

Sam68 Promotes the Progression of Human Breast Cancer through inducing Activation of EphA3

BACKGROUND

Src associated with mitosis of 68 kDa (Sam68), is often highly expressed in human cancers. Overexpression of Sam68 has been shown to be correlated with poor survival prognosis in some cancer patients. However, little is known whether Sam68 plays a role in promoting metastasis in breast cancer.

MATERIALS AND METHODS

The expression of Sam68 protein in breast cancer tissue was detected by immunohistochemistry. Trans-well assay, wound-healing, real-time PCR and Western blotting analysis were used to detect the effect of Sam68 on promoting EMT or metastasis of breast cancer. Next-generation RNA sequencing was used to analyze genes that may be regulated by Sam68.

RESULTS

Sam68 plays a positive role in promoting breast cancer metastasis. Sam68 was found to be overexpressed in breast cancer along with lymph node metastasis. MMP-9 was also found to be overexpressed in breast cancer tissue and was correlated to the expression of Sam68 (P<0.01). Xenograft in NOD/SCID mice and in vitro experiments confirmed that the invasion and metastatic ability of breast cancer cells were regulated by Sam68. And EPHA3 could be up-regulated by Sam68 in breast cancer.

CONCLUSION

High expression of Sam68 participates in breast cancer metastasis by up-regulating the EPHA3 gene.

SAM68 promotes tumorigenesis in lung adenocarcinoma by regulating metabolic conversion via PKM alternative splicing

Background: A metabolic "switch" from oxidative phosphorylation to glycolysis provides tumor cells with energy and biosynthetic substrates, thereby promoting tumorigenesis and malignant progression. However, the mechanisms controlling this metabolic switch in tumors is not entirely clear. Methods: Clinical specimens were used to determine the effect of SAM68 on lung adenocarcinoma (LUAD) tumorigenesis and metastasis, and mouse models and molecular biology assays were performed to elucidate the function and underlying mechanisms in vitro and in vivo. Results:SAM68 mRNA levels were higher in LUAD tissue than in normal lung tissue, indicating that SAM68 expression is upregulated in LUAD. Patients with LUAD with SAM68high (n = 257) had a higher frequency of tumor recurrence (p = 0.025) and recurrence-free survival (p = 0.013) than did those with SAM68low (n = 257). Patients with SAM68high mRNA levels (n = 257) were at a higher risk for cancer-related death (p = 0.006), and had shorter overall survival (p = 0.044) than did those with SAM68low. SAM68 promotes tumorigenesis and metastasis of LUAD cells in vitro and in vivo by regulating the cancer metabolic switch. SAM68 drives cancer metabolism by mediating alternative splicing of pyruvate kinase (PKM) pre-mRNAs, and promoting the formation of PKM2. Mechanistically, SAM68 increased the binding of the splicing repressor hnRNP A1 to exon 9 of PKM, thereby enhancing PKM2 isoform formation and PKM2-dependent aerobic glycolysis and tumorigenesis. Conclusions: SAM68 promotes LUAD cell tumorigenesis and cancer metabolic programming via binding of the 351-443 aa region of SAM68 to the RGG motif of hnRNP A1, driving hnRNP A1-dependent PKM splicing, contributing to increased oncogene PKM2 isoform formation and inhibition of PKM1 isoform formation. SAM68 is therefore a promising therapeutic target for the treatment of LUAD.

Molecular landscape of recurrent cervical cancer

Cervical cancer (CC) is a major gynecological problem in developing and underdeveloped countries. Despite the significant advancement in early detection and treatment modalities, several patients recur. Moreover, the molecular mechanisms responsible for CC recurrence remains obscure. The patients with CC recurrence often show poor prognosis and significantly high mortality rates. The clinical management of recurrent CC depends on treatment history, site, and extent of the recurrence. Owing to poor prognosis and limited treatment options, recurrent CC often presents a challenge to the clinicians. Several in vitro, in vivo, and patient studies have led to the identification of the critical molecular changes responsible for CC recurrence. Both aberrant genetic and epigenetic modifications leading to altered cell signaling pathways have been reported to impact CC recurrence. Researchers are currently trying to dissect the molecular pathways in CC and translate these findings for better management of disease. This article attempts to review the existing knowledge of disease relapse, accompanying challenges, and associated molecular players in CC.

Leptin, Leptin Receptor, KHDRBS1 (KH RNA Binding Domain Containing, Signal Transduction Associated 1), and Adiponectin in Bone Metastasis from Breast Carcinoma: An Immunohistochemical Study

Breast cancer patients are at a high risk of complications from bone metastasis. Molecular characterization of bone metastases is essential for the discovery of new therapeutic targets. Here, we investigated the expression and the intracellular distribution of KH RNA binding domain containing, signal transduction associated 1 (KHDRBS1), leptin, leptin receptor (LEPR), and adiponectin in bone metastasis from breast carcinoma and looked for correlations between the data. The expression of these proteins is known in breast carcinoma, but it has not been investigated in bone metastatic tissue to date. Immunohistochemical analysis was carried out on bone metastasis specimens, then semiquantitative evaluation of the results and the Pearson test were performed to determine eventual correlations. KHDRBS1 expression was significantly higher in the nuclei than in the cytosol of metastatic cells; LEPR was prevalently observed in the cytosol and the nuclei; leptin and adiponectin were found in metastatic cells and stromal cells; the strongest positive correlation was between nuclear KHDRBS1 and nuclear LEPR expression. Taken together, our findings support the importance of the leptin/LEPR/KHDRBS1 axis and of adiponectin in the progression of bone metastasis and suggest their potential application in pharmacological interventions.

HN1 promotes tumor associated lymphangiogenesis and lymph node metastasis via NF-κB signaling activation in cervical carcinoma

Lymph node metastasis (LNM) is a critical cause for disease progression and treatment failure in cervical cancer. However, the mechanism underlying cervical cancer LNM remains unclear. In this study, HN1 was found to be dramatically upregulated in cervical cancer and patients with higher HN1 expression are more likely to exhibit a higher rate of LNM and lower survival rate. Univariate and multivariate Cox-regression analyses showed that HN1 is an independent prognostic factor in cervical cancer. Meanwhile, HN1 promotes lymphangiogenesis of cervical cancer in vitro. The in vivo experiment also indicates that HN1 enhances LNM in cervical cancer. Furthermore, we also found that HN1 activated the NF-κB signaling pathway to enhance the expression of downstream genes. Taken together, our study suggests that HN1 plays a crucial role in promoting LNM and acts as a prognostic biomarker in cervical cancer.

The Role of RNA Splicing Factors in Cancer: Regulation of Viral and Human Gene Expression in Human Papillomavirus-Related Cervical Cancer

The spliceosomal complex components, together with the heterogeneous nuclear ribonucleoproteins (hnRNPs) and serine/arginine-rich (SR) proteins, regulate the process of constitutive and alternative splicing, the latter leading to the production of mRNA isoforms coding multiple proteins from a single pre-mRNA molecule. The expression of splicing factors is frequently deregulated in different cancer types causing the generation of oncogenic proteins involved in cancer hallmarks. Cervical cancer is caused by persistent infection with oncogenic human papillomaviruses (HPVs) and constitutive expression of viral oncogenes. The aberrant activity of hnRNPs and SR proteins in cervical neoplasia has been shown to trigger the production of oncoproteins through the processing of pre-mRNA transcripts either derived from human genes or HPV genomes. Indeed, hnRNP and SR splicing factors have been shown to regulate the production of viral oncoprotein isoforms necessary for the completion of viral life cycle and for cell transformation. Target-therapy strategies against hnRNPs and SR proteins, causing simultaneous reduction of oncogenic factors and inhibition of HPV replication, are under development. In this review, we describe the current knowledge of the functional link between RNA splicing factors and deregulated cellular as well as viral RNA maturation in cervical cancer and the opportunity of new therapeutic strategies.

A five-mRNA signature associated with post-translational modifications can better predict recurrence and survival in cervical cancer

High mortality of patients with cervical cancer (CC) stresses the imperative of prognostic biomarkers for CC patients. Additionally, the vital status of post‐translational modifications (PTMs) in the progression of cancers has been reported by numerous researches. Therefore, the purpose of this research was to dig a prognostic signature correlated with PTMs for CC. We built a five‐mRNA (GALNTL6, ARSE, DPAGT1, GANAB and FURIN) prognostic signature associated with PTMs to predict both disease‐free survival (DFS) (hazard ratio [HR] = 3.967, 95% CI = 1.985‐7.927; P < .001) and overall survival (HR = 2.092, 95% CI = 1.138‐3.847; P = .018) for CC using data from The Cancer Genome Atlas database. Then, the robustness of the signature was validated using GSE44001 and the Human Protein Atlas (HPA) database. CIBERSORT algorithm analysis displayed that activated CD4 memory T cell was also an independent indicator for DFS (HR = 0.426, 95% CI = 0.186‐0.978; P = .044) which could add additional prognostic value to the signature. Collectively, the PTM‐related signature and activated CD4 memory T cell can provide new avenues for the prognostic predication of CC. These findings give further insights into effective treatment strategies for CC, providing opportunities for further experimental and clinical validations.

MicroRNA-21 promotes cell metastasis in cervical cancer through modulating epithelial-mesenchymal transition

MicroRNA (miR)-21 is known to act as an oncogene in cervical cancer by promoting cell proliferation and migration; however, the underlying molecular mechanisms have remained to be fully elucidated. The present study revealed that the gene expression levels of miR-21 and epithelial-mesenchymal transition (EMT)-associated transcription factor Zinc finger E-box-binding homeobox 1 (ZEB1), in cervical cancer and lymphatic metastatic carcinoma tissues were significantly higher than those in normal tissues (P<0.05). Furthermore, the gene expression levels of miR-21 and ZEB1 were positively associated with muscular infiltration depth, parametrical invasion and lymph node metastasis in patients with cervical cancer. Immunohistochemistry assays indicated that the expression levels of ZEB1 and the mesenchymal cell marker Vimentin in cervical cancer tissues were significantly higher than those in normal cervical tissues (P<0.05). Overexpression of miR-21 in HeLa and SiHa cells caused the upregulation of the mesenchymal cell markers Vimentin and N-cadherin, and downregulation of the epithelial cell marker E-cadherin at the proteins level. In addition, overexpression of miR-21 enhanced the invasiveness of HeLa and SiHa cells. These results demonstrated that miR-21 was upregulated in cervical cancer tissues and promoted cell metastasis through modulating EMT. A better understanding of the role of miR-21 and EMT may lead to the development of more effective therapies for patients with cervical cancer.

KMT Set7/9 is a new regulator of Sam68 STAR-protein

Lysine-specific methyltransferase Set7/9 (KMT7) belongs to the SET domain family of proteins. Besides the SET domain, Set7/9 also contains a so-called MORN (Membrane Occupation and Recognition Nexus) domain whose function in high eukaryotes is largely unknown. Set7/9 has been shown to specifically methylate both histones H1 and H3 as well as a number of non-histone substrates, including p53, E2F1, RelA, AR, and other important transcription factors. However, despite the ever growing list of potential substrates of Set7/9, the question of its substrate specificity is still debatable. To gain a better understanding of the Set7/9 substrate specificity and to clarify the importance of structural domains of Set7/9 for protein-protein interactions (PPIs) we determined interactomes for both MORN and SET domains of Set7/9 by pull-down assay coupled with mass-spectrometry. Importantly, we demonstrated that most of PPIs of Set7/9 are mediated via its MORN domain. The latter has preference towards positively charged amino acids that are often found in RNA-binding proteins. One of the Set7/9-interacting proteins was identified as Sam68, an RNA splicing protein with a KH (heterogeneous nuclear ribonucleoprotein K (hnRNP K) homology) domain. Importantly, the RG-rich domain of Sam68 that is also present in many splicing factors was found to interact with Set7/9. We revealed that Set7/9 not only co-immunoprecipitated with Sam68, but also methylated the latter on K208. Functionally, knockout of Set7/9 decreased the protein level of Sam68 in cells resulting in altered regulation of cell cycle and apoptosis. Finally, the bioinformatics analysis established a correlation between the high levels of Sam68/Set7/9 co-expression and better survival rates of patients with colon cancer.

Leptin, Adiponectin, and Sam68 in Bone Metastasis from Breast Cancer

The most serious aspect of neoplastic disease is the spread of cancer cells to secondary sites. Skeletal metastases can escape detection long after treatment of the primary tumour and follow-up. Bone tissue is a breeding ground for many types of cancer cells, especially those derived from the breast, prostate, and lung. Despite advances in diagnosis and therapeutic strategies, bone metastases still have a profound impact on quality of life and survival and are often responsible for the fatal outcome of the disease. Bone and the bone marrow environment contain a wide variety of cells. No longer considered a passive filler, bone marrow adipocytes have emerged as critical contributors to cancer progression. Released by adipocytes, adipokines are soluble factors with hormone-like functions and are currently believed to affect tumour development. Src-associated in mitosis of 68 kDa (Sam68), originally discovered as a protein physically associated with and phosphorylated by c-Src during mitosis, is now recognised as an important RNA-binding protein linked to tumour onset and progression of disease. Sam68 also regulates splicing events and recent evidence reports that dysregulation of these events is a key step in neoplastic transformation and tumour progression. The present review reports recent findings on adipokines and Sam68 and their role in breast cancer progression and metastasis.

A comprehensive study on genome-wide coexpression network of KHDRBS1/Sam68 reveals its cancer and patient-specific association

Human KHDRBS1/Sam68 is an oncogenic splicing factor involved in signal transduction and pre-mRNA splicing. We explored the molecular mechanism of KHDRBS1 to be a prognostic marker in four different cancers. Within specific cancer, including kidney renal papillary cell carcinoma (KIRP), lung adenocarcinoma (LUAD), acute myeloid leukemia (LAML), and ovarian cancer (OV), KHDRBS1 expression is heterogeneous and patient specific. In KIRP and LUAD, higher expression of KHDRBS1 affects the patient survival, but not in LAML and OV. Genome-wide coexpression analysis reveals genes and transcripts which are coexpressed with KHDRBS1 in KIRP and LUAD, form the functional modules which are majorly involved in cancer-specific events. However, in case of LAML and OV, such modules are absent. Irrespective of the higher expression of KHDRBS1, the significant divergence of its biological roles and prognostic value is due to its cancer-specific interaction partners and correlation networks. We conclude that rewiring of KHDRBS1 interactions in cancer is directly associated with patient prognosis.

Integrated analysis of long noncoding RNA expression profiles in lymph node metastasis of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, and metastasis of HCC is the leading cause of poor prognosis. Among all the extrahepatic metastases, lymph node metastasis (LNM) is common, second only to lung metastasis. However, the pathogenesis of HCC LNM remains largely unknown.

METHODS

Microarray was performed to investigate the long noncoding RNA (lncRNA) and messenger RNA (mRNA) expression profiles in serum samples from HCC LNM patients (N = 4) and HCC non-LNM controls (N = 5). Subsequently, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was applied to validate the expression levels of randomly selected differential lncRNAs and mRNAs. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were employed to explore the potential functions of differentially expressed mRNAs. Co-expression networks were further constructed to elucidate the interactions of the differential genes and to speculate on the potential functions of the dominant lncRNAs. In this research, we attempted to illuminate the correlations between lncRNA and HCC LNM.

RESULTS

Compared with the non-LNM group, a total of 234 lncRNAs and 58 mRNAs were obtained as significantly dysregulated genes in LNM group (p < 0.05, fold change ≥ 2). Functional enrichment analyses showed that upregulated mRNAs are mostly enriched for glucose-6-phosphate dehydrogenase activity, biotin binding and AP-3 adaptor complex, while the downregulated mRNAs are enriched for macrophage colony-stimulating factor receptor binding, succinate-CoA ligase activity and palmitoyltransferase activity. In addition, coexpression network revealed that the dominant lncRNAs are potential participants of protein metabolic process, integral component of membrane, RNA binding, Golgi apparatus, as well as focal adhesion pathway.

CONCLUSION

This study first revealed the expression profiles and potential functions of dysregulated lncRNAs and mRNAs in HCC LNM, which may provide novel clues for further studies on HCC LNM.

The p53 status can influence the role of Sam68 in tumorigenesis

The expression and activities of RNA binding proteins are frequently dysregulated in human cancer. Their roles, however, appears to be complex, with reports indicating both pro-tumorigenic and tumor suppressive functions. Here we show, using two classical mouse cancer models, that the role of KH-type RNA binding protein, Sam68, in tumor development can be influenced by the status of the p53 tumor suppressor. We demonstrate that in mice expressing wild type p53, Sam68-deficiency resulted in a higher incidence and malignancy of carcinogen-induced tumors, suggesting a tumor suppressive role for Sam68. In marked contrast, Sam68-haploinsufficiency significantly delayed the onset of tumors in mice lacking p53 and prolonged their survival, indicating that Sam68 accelerates the development of p53-deficient tumors. These findings provide considerable insight into a previously unknown relationship between Sam68 and the p53 tumor suppressor in tumorigenesis.

High expression of Sam68 in sacral chordomas is associated with worse clinical outcomes

Src-associated in mitosis of 68 kDa (Sam68), also known as KHDRBS1 (KH domain-containing, RNA-binding, signal transduction-associated 1), is a member of the signal transduction and activation of RNA family. Previous studies have demonstrated that the aberrant expression of Sam68 is associated with the progression and prognosis of a variety of cancers, but little is known about its expression and role in chordomas, which are rare and aggressive bone neoplasms. In this study, we analyzed 40 tumor tissues and 20 distant normal tissues obtained from 40 patients with sacral chordoma using immunohistochemistry, and observed the expression of Sam68 was significantly upregulated in sacral chordomas compared with normal tissues (P=0.001). A positive correlation between the expression of Sam68 and the cell proliferation index Ki-67 was determined using Spearman’s rank correlation test (γ =0.599, P<0.001). In addition, high expression of Sam68 was significantly associated with surrounding muscle invasion (P<0.001). Moreover, Kaplan–Meier curves showed that patients with overexpressed Sam68 had shorter local recurrence-free survival time (P<0.001). Lastly, multivariate analysis indicated that Sam68 is an independent prognostic factor for the local recurrence-free survival of sacral chordomas (hazard ratio =5.929, 95% CI: 1.092–32.188, P=0.039). Our findings suggest the use of Sam68 as a predictor for the recurrence of sacral chordomas.

High expression of FUNDC1 predicts poor prognostic outcomes and is a promising target to improve chemoradiotherapy effects in patients with cervical cancer

FUN14 domain containing 1 (FUNDC1) is an important molecule in receptor‐dependent mitophagy. However, the roles of FUNDC1 in human cancer biology remain unknown. The aim of this study was to explore the expression and roles of FUNDC1 in cervical cancer. Immunohistochemistry and Western blotting were applied to detect the expression of FUNDC1, and small‐hairpin RNA was applied to inhibit the expression of endogenous FUNDC1 in cervical cancer cells. MTT assays and Flow cytometric analysis were applied to examine cell proliferation and apoptosis. Immunofluorescence was used to detect the formation of γH2AX foci and evaluate the extent of DNA damage. Compared with corresponding adjacent noncancerous cervical tissues, the expression of FUNDC1 in cervical cancer cells was significantly increased. High expression of FUNDC1 and the prognosis of patients with cervical cancer were correlated negatively, which could be used as an independent prognostic factor for overall survival and disease‐free survival. Depletion of FUNDC1 significantly inhibited the proliferation of tumor cells, induced apoptosis, and enhanced cell sensitivity to cisplatin and ionizing radiation (IR). Our data suggested that FUNDC1 can be used as a prognostic biomarker in patients with cervical cancer, and may be a new therapeutic target to improve the antitumor effects of chemoradiotherapy.

Combined Knockdown of D-dopachrome Tautomerase and Migration Inhibitory Factor Inhibits the Proliferation, Migration, and Invasion in Human Cervical Cancer

Objective

D-dopachrome tautomerase (D-DT) is a homologue of macrophage migration inhibitory factor (MIF) with similar functions. However, the possible biological roles of D-DT in cervical cancer remain unknown so far.

Methods

D-dopachrome tautomerase was assessed by immunohistochemistry in 83 cervical cancer and 31 normal cervix tissues. The stable knockdown of D-DT and MIF by lentivirus-delivered short hairpin RNA was established, and tumor growth was examined in vitro and in vivo. The effects of D-DT and MIF on the migration and invasion were further detected by wound healing assay and transwell assay. Western blot was used to explore the mechanism of D-DT and MIF in cervical cancer pathogenesis.

Results

We found that D-DT was significantly high in cervical cancer, which correlated with lymph node metastasis. The knockdown of D-DT and MIF, individually and additively, inhibited the proliferation, migration, and invasion in HeLa and SiHa cells and restrained the growth of xenograft tumor. The ablation of D-DT and MIF rescued the expression of E-cadherin and inhibited the expression of PCNA, cyclin D1, gankyrin, Sam68, and vimentin, as well as phospho-Akt and phospho-glycogen synthase kinase 3-β.

Conclusions

The inhibition of D-DT and MIF in combination may represent a potential therapeutic strategy for cervical cancer.

HBXIP over expression as an independent biomarker for cervical cancer

BACKGROUND

Emerging evidence demonstrated that hepatitis B virus X-interacting protein (HBXIP) has broad roles in cancers. However, high-level expression of HBXIP has been correlated with human malignancies, suggesting roles in carcinogenesis and tumor progression. The aim of the study is to investigate the role and mechanism of HBXIP oncogene and the correlation to the clinicopathological status in cervical cancers.

METHODS

A total of 107 cervical cancer patients with strict follow-up, 105 cervical intraepithelial neoplasia (CIN) and 31 normal cervical epithelia samples were selected for immunohistochemical (IHC) staining of HBXIP protein. Additionally, the cervical cancer cell line of SiHa was included in this study. The relationship between HBXIP expression and clinicopathological characteristics were analyzed to verify the clinical value of HBXIP protein expression in patient prognosis, and survival rates were calculated using the Kaplan-Meier method.

RESULTS

HBXIP protein showed a mainly cytoplasmic staining pattern in cervical cancers by using IHC staining in paraffin embedded cervical cancer tissues and IF staining in SiHa cervical cancer cells. The strongly positive rate of HBXIP protein expression was significantly higher in cervical SCCs and CINs than in normal cervical epithelia. HBXIP protein over-expression was significantly correlated with the clinical stage, differentiation, lymph node metastasis, HPV infection, the over-expression of P63 and overall survival rates in cervical cancer. All of these data defined that HBXIP was involved in the progression of the cervical cancer. However, the detailed mechanism need to the further study.

CONCLUSIONS

HBXIP over-expression appears to associate with cervical cancer progression, and may potentially be used as a cervical cancer biomarker for the early diagnosis, prognostic evaluation and therapeutic target for cervical cancer.

NR2F6 Expression Correlates with Pelvic Lymph Node Metastasis and Poor Prognosis in Early-Stage Cervical Cancer

Background: There is an abnormal expression of nuclear receptor subfamily 2 group F member 6 (NR2F6) in human cancers such as breast cancer, colon cancer, and acute myelogenous leukemia. However, its clinical significance in cervical cancer has not been established. We explored NR2F6 expression and its clinicopathological significance in early-stage cervical cancer. Methods: NR2F6 expression in cervical cancer cell lines and cervical cancer tissues was determined by Western blotting, real-time PCR, and immunochemistry (IHC). NR2F6 expression in 189 human early-stage cervical cancer tissue samples was evaluated using IHC. The relevance between NR2F6 expression and early-stage cervical cancer prognosis and clinicopathological features was determined. Results: There was marked NR2F6 mRNA and protein overexpression in the cervical cancer cells and clinical tissues compared with an immortalized squamous cell line and adjacent noncancerous cervical tissues, respectively. In the 189 cervical cancer samples, NR2F6 expression was positively related to International Federation of Gynecology and Obstetrics (FIGO) stage (p = 0.006), squamous cell carcinoma antigen (p = 0.006), vital status (p < 0.001), tumor recurrence (p = 0.001), chemotherapy (p = 0.039), and lymph node metastasis (p < 0.001). Overall and disease-free survival was shorter in patients with early-stage cervical cancer and higher NR2F6 levels than in patients with lower levels of NR2F6. Univariate and multivariate analysis determined that NR2F6 was an independent prognostic factor of survival in early-stage cervical cancer. Conclusions: Taken together, our findings suggest that high NR2F6 expression predicts pelvic lymph node metastasis, tumor recurrence and poor prognosis in early-stage cervical cancer. NR2F6 might be a novel prognostic biomarker and potential therapeutic target of cervical cancer.

Expression of Sam68 Correlates With Cell Proliferation and Survival in Epithelial Ovarian Cancer

Src associated in mitosis, 68 kDa (Sam68) is a KH domain RNA-binding protein that belongs to the signal transduction and activation of RNA family. It is a multifunctional protein known to regulate cellular signal transduction, transcription, RNA metabolism, proliferation, and apoptosis, thus implicated in tumor growth. Herein, we investigated the clinical significance of Sam68 in human epithelial ovarian cancer (EOC). Western blot and immunohistochemical staining demonstrated that Sam68 expression was upregulated in EOC tissues and cell lines. Statistical analysis showed that high expression of Sam68 correlated with poor prognosis of patients with EOC. In vitro, serum starvation-refeeding experiment was primarily performed to confirm that Sam68 participated in the cell cycle progression of EOC cell lines. Then knocking down Sam68 level with small interfering RNA, cell cycle was arrested at G1 phase and cell proliferation impaired. Furthermore, we demonstrated that the antiproliferative effect of silencing Sam68 in EOC cells was associated with the upregulation of cyclin-dependent kinase inhibitors p21^Cip1 and p27^Kip1, along with the downregulation of p-FOXO3a, p-Akt, and p-GSK-3β. Taken together, our findings uncovered that Sam68 played an important role in promoting the proliferation of human ovarian cancer, thereby might be a novel therapeutic target for EOC.

Sam68 is Overexpressed in Epithelial Ovarian Cancer and Promotes Tumor Cell Proliferation

BACKGROUND Epithelial ovarian cancer (EOC) is the deadliest gynecological malignancy, and evidence is accumulating on how molecular markers may be associated with the origin and process of EOC. Sam68 (Src-associated in mitosis, of 68 kD), is a K homology domain RNA-binding protein that has been investigated as a risk factor in multiple types of tumors. The aim of the present study was to investigate the contribution of the Sam68 gene in the pathogenesis of EOC. MATERIAL AND METHODS Western blot assay and real-time quantitative PCR methods were performed to examine Sam68 expression in EOC tissue specimens. The association of Sam68 expression with clinic-pathologic variables of EOC was evaluated. Then gain-of-function and loss-of-function strategies were adopted to examine the regulation of Sam68 on the proliferation of EOC OVCAR-3 cells using CCK-8 and colony forming assays. RESULTS Sam68 was overexpressed in both mRNA and protein levels in EOC tumor tissue (n=152) in an association with malignant factors of EOC such as International Federation of Gynecology and Obstetrics (FIGO) stage, residual tumor size (cm), histological grade, and lymph node metastasis. In vitro results demonstrated that Sam68 overexpression was upregulated while Sam68 knockdown downregulated the proliferation of EOC OVCAR-3 cells via regulation of cell growth and colony formation. CONCLUSIONS Sam68 was overexpressed in EOC tissue in association with such cancer malignant factors of FIGO stage, histological grade, and lymph node metastasis, and also positively regulated the proliferation of EOC cells. Our research suggests that Sam68 might accelerate cell cycle progression, and present as a prognostic marker for EOC.

WNT2 Promotes Cervical Carcinoma Metastasis and Induction of Epithelial-Mesenchymal Transition

Background

Previously, we found an 11-gene signature could predict pelvic lymph node metastasis (PLNM), and WNT2 is one of the key genes in the signature. This study explored the expression and underlying mechanism of WNT2 in PLNM of cervical cancer.

Methods

WNT2 expression level in cervical cancer was detected using western blotting, quantitative PCR, and immunohistochemistry. Two WNT2-specific small interfering RNAs (siRNAs) were used to explore the effects of WNT2 on invasive and metastatic ability of cancer cells, and to reveal the possible mechanism of WNT2 affecting epithelial—mesenchymal transition (EMT). The correlation between WNT2 expression and PLNM was further investigated in clinical cervical specimens.

Results

Both WNT2 mRNA and protein expression was upregulated in cervical cancer. High WNT2 expression was significantly associated with tumor size, lymphovascular space involvement, positive parametrium, and most importantly, PLNM. PLNM and WNT2 expression were independent prognostic factors for overall survival and disease-free survival. WNT2 knockdown inhibited SiHa cell motility and invasion and reversed EMT by inhibiting the WNT2/β-catenin pathway. WNT2 overexpression in cervical cancer was associated with β-catenin activation and induction of EMT, which further contributed to metastasis in cervical cancer.

Conclusion

WNT2 might be a novel predictor of PLNM and a promising prognostic indicator in cervical cancer.

Sam68 functions as a transcriptional coactivator of the p53 tumor suppressor

Sam68 is a known sequence-specific RNA binding protein that regulates alternative splicing events during the cell cycle and apoptosis. Sam68 has also been shown to influence transcription, but the molecular mechanism remains undefined. Herein we identify Sam68 as a transcriptional coactivator of the p53 tumor suppressor in response to DNA damage. Using CRISPR/Cas9 generated isogenic HCT116 Sam68^−/− cell lines wild type or deficient for p53, we show that Sam68 is required for the efficient transactivation of p53 target genes. Consistently, Sam68 depletion caused defects in DNA damage-induced cell cycle arrest and apoptosis mediated by p53. Mechanistically, we demonstrate that Sam68 physically interacted with p53 in an RNA-dependent manner, and that this interaction was essential for the coactivator function of Sam68. Furthermore, we show that both Sam68 and p53 were recruited to promoters of p53-responsive genes, suggesting interdependence. Finally, Sam68 acted in concert with the p53 long noncoding RNA (lncRNA) target PR-lncRNA-1 for p53 recruitment, implicating a positive-feedback mechanism in which lncRNAs induced by the Sam68/p53 complex can enhance p53 transcriptional activity. These findings define a hitherto novel mechanism of action for Sam68 in governing p53 transcriptional activation, and represent the first report of Sam68 in the regulation of tumor suppressor activities.

Sam68 modulates apoptosis of intestinal epithelial cells via mediating NF-κB activation in ulcerative colitis

Sam68 (Src-associated substrate during mitosis of 68 KDa), also known as KHDRBS1 (KH domain containing, RNA binding, signal transduction associated 1), belongs to the prototypic member of the signal transduction activator of RNA (STAR) family of RNA-binding proteins. Sam68 is implicated in various cellular processes including RNA metabolism, apoptosis, signal transduction. Previous researches demonstrated that Sam68 regulated nuclear transcription factor kappa B (NF-κB) to induce inflammation. However, the expression and biological functions of Sam68 in ulcerative colitis (UC) are not clear. In this study, we reported for the first time that Sam68 was up-regulated in intestinal epithelial cells (IECs) of patients with UC. In DSS-induced mouse colitis model, we observed the overexpression of Sam68 accompanied with increased levels of IEC apoptotic markers (active caspase-3 and cleaved PARP) and NF-κB activation indicators (p-p65 and p-IκB) in colitis IECs. Co-localization of Sam68 with active caspase-3 (and p-p65) in IECs of the DSS-induced colitis group further indicated the possible involvement of NF-κB-mediated IEC apoptosis. Applying TNF-α-treated HT-29 cells as an in vitro IEC inflammation model, we confirmed the positive correlation amomg Sam68, NF-κB activation and caspase-dependent apoptosis. Immunofluorescence and immunoprecipitation assay identified nuclear translocation and physical interaction of Sam68 and NF-κB subunits in TNF-α-treated HT-29 cells. Besides, depletion of Sam68 by RNA interference greatly alleviated NF-κB activation and apoptosis in TNF-α-treated HT-29 cells. Taken together, our results indicated that Sam68 modulates apoptosis of intestinal epithelial cells via mediating NF-κB activation in UC.

Pathogenic Network Analysis Predicts Candidate Genes for Cervical Cancer

Purpose. The objective of our study was to predicate candidate genes in cervical cancer (CC) using a network-based strategy and to understand the pathogenic process of CC. Methods. A pathogenic network of CC was extracted based on known pathogenic genes (seed genes) and differentially expressed genes (DEGs) between CC and normal controls. Subsequently, cluster analysis was performed to identify the subnetworks in the pathogenic network using ClusterONE. Each gene in the pathogenic network was assigned a weight value, and then candidate genes were obtained based on the weight distribution. Eventually, pathway enrichment analysis for candidate genes was performed. Results. In this work, a total of 330 DEGs were identified between CC and normal controls. From the pathogenic network, 2 intensely connected clusters were extracted, and a total of 52 candidate genes were detected under the weight values greater than 0.10. Among these candidate genes, VIM had the highest weight value. Moreover, candidate genes MMP1, CDC45, and CAT were, respectively, enriched in pathway in cancer, cell cycle, and methane metabolism. Conclusion. Candidate pathogenic genes including MMP1, CDC45, CAT, and VIM might be involved in the pathogenesis of CC. We believe that our results can provide theoretical guidelines for future clinical application.

B3GNT3 Expression Is a Novel Marker Correlated with Pelvic Lymph Node Metastasis and Poor Clinical Outcome in Early-Stage Cervical Cancer

BACKGROUND

The β1,3-N-acetylglucosaminyltransferase-3 gene (B3GNT3) encodes a member of the B3GNT family that functions as the backbone structure of dimeric sialyl-Lewis A and is involved in L-selectin ligand biosynthesis, lymphocyte homing and lymphocyte trafficking. B3GNT3 has been implicated as an important element in the development of certain cancers. However, the characteristics of B3GNT3 in the development and progression of cancer remain largely unknown. Thus, our study aimed to investigate the expression pattern and the prognostic value of B3GNT3 in patients with early-stage cervical cancer.

METHODS

The mRNA and protein levels of B3GNT3 expression were examined in eight cervical cancer cell lines and ten paired cervical cancer tumors, using real-time PCR and western blotting, respectively. Immunohistochemistry (IHC) was used to analyze B3GNT3 protein expression in paraffin-embedded tissues from 196 early-stage cervical cancer patients. Statistical analyses were applied to evaluate the association between B3GNT3 expression scores and clinical parameters, as well as patient survival.

RESULTS

B3GNT3 expression was significantly upregulated in cervical cancer cell lines and lesions compared with normal cells and adjacent noncancerous cervical tissues. In the 196 cases of tested early-stage cervical cancer samples, the B3GNT3 protein level was positively correlated with high risk TYPES of human papillomavirus (HPV) infection (P = 0.026), FIGO stage (P < 0.001), tumor size (P = 0.025), tumor recurrence (P = 0.004), vital status (P < 0.001), concurrent chemotherapy and radiotherapy (P = 0.016), lymphovascular space involvement (P = 0.003) and most importantly, lymph node metastasis (P = 0.003). Patients with high B3GNT3 expression had a shorter overall survival (OS) and disease-free survival (DFS) compared with those with low expression of this protein. Multivariate analysis suggested that B3GNT3 expression is an independent prognostic indicator for cervical cancer patients.

CONCLUSIONS

Our study demonstrated that elevated B3GNT3 expression is associated with pelvic lymph node metastasis and poor outcome in early-stage cervical cancer patients. B3GNT3 may be a novel prognostic marker and therapeutic target for the treatment of cervical cancer.

CONSORT: Sam68 Is Directly Regulated by MiR-204 and Promotes the Self-Renewal Potential of Breast Cancer Cells by Activating the Wnt/Beta-Catenin Signaling Pathway

Breast cancer stem cells (BCSCs) are considered to be responsible for recurrence in breast cancer. The 68 kDa Src-associated protein in mitosis (Sam68) has been linked to the development and progression of breast cancer; however, the posttranscriptional regulation and role of Sam68 in BCSC self-renewal remain unclear.Sam68 was ectopically overexpressed or knocked down using a siRNA; the self-renewal potential of breast cancer cell lines was assessed using flow cytometry, in vitro mammosphere culture and a xenograft model in NOD/SCID mice. Activation of beta-catenin was assessed by immunohistochemical staining, Western blotting, and luciferase reporter gene assays. The ArrayExpress dataset GSE45666 was used to identify conserved microRNAs downregulated in breast cancer; real-time PCR, Western blotting, luciferase reporter assay, and xenografted tumor model were used to confirm miR-204 regulated Sam68.We found that endogenous Sam68 expression correlated positively with the self-renewal potential of breast cancer cell lines. Overexpression of Sam68 promoted, whereas knockdown reduced, breast cancer cell self-renewal potential in vitro and tumorigenicity in vivo. The Wnt/beta-catenin pathway was identified as a functional mediator of Sam68-induced self-renewal in SKBR-3 and MCF-7 cells. Furthermore, miR-204 was found to be frequently downregulated in human breast cancer and confirmed to directly target Sam68; miR-204 inhibited the self-renewal of breast cancer cell lines by targeting and suppressing Sam68.Our study reveals that Sam68 is regulated by miR-204 and may play an important role in the self-renewal of BCSCs via activating the Wnt/beta-catenin pathway. Sam68 may represent a novel therapeutic target for breast cancer.

Sam68 regulates cell proliferation and cell adhesion-mediated drug resistance (CAM-DR) via the AKT pathway in non-Hodgkin's lymphoma

OBJECTIVES

Sam68 (Src-associated in mitosis 68 kDa), a substrate for tyrosine kinase c-Src during mitosis, is up-regulated in a variety of human cancers and acts oncogenically promoting tumour progression. This study has explored biological function and clinical significance of Sam68 in non-Hodgkin's lymphoma (NHL).

MATERIALS AND METHODS

To examine Sam68 expression in NHL, clinically, eight diffuse large B-cell lymphomas and four reactive lymphoid hyperplasia fresh-frozen tissues were obtained for western blot and quantitative real-time PCR analyses. Using immunohistochemical staining, paraffin wax embedded sections from 164 cases of NHL patients were used to evaluate prognostic value of Sam68. Cell Counting Kit-8 (CCK-8) and soft agar colony assays were conducted to investigate the role of Sam68 in cell viability and cell proliferation respectively. Furthermore, effects of Sam68 on cell adhesion-mediated drug resistance (CAM-DR) was determined by CCK-8 assay and flow cytometric analysis.

RESULTS

Expression status of Sam68 inversely correlated with clinical outcomes of patients with NHL, and it was also an independent prognostic factor for the outcomes. In addition, Sam68 was associated with proliferation of NHL cells. Knock-down of its gene inhibited cell proliferation and colony formation by delaying cell cycle progression. Furthermore, OCI-Ly8 and Jeko-1 cells adhering to FN and HS-5 expressed higher Sam68 protein, compared to their suspension counterparts. Sam68 promoted cell adhesion-mediated drug resistance (CAM-DR) via the AKT pathway.

CONCLUSIONS

Increased Sam68 expression in NHL resulted in poor prognosis, and it promoted CAM-DR in NHL via AKT.

The RNA-binding protein Sam68 regulates tumor cell viability and hepatic carcinogenesis by inhibiting the transcriptional activity of FOXOs

Src associated in mitosis (Sam68; 68 kDa) is a KH domain RNA-binding protein that belongs to the signal transduction and activation of RNA family, and has been implicated in the oncogenesis and progression of several human cancers. Our study aimed to investigated the clinicopathologic significance of Sam68 expression and its role in cell proliferation and the underlying molecular mechanism in hepatocellular carcinoma (HCC). We demonstrated that Sam68 expression was significantly increased in HCC and high expression of Sam68 was significantly associated with Edmondson grade, tumor size, tumor nodule number, HBsAg status and Ki-67 expression. The Kaplan-Meier survival curves showed that increased expression of Sam68 was correlated with poor prognosis in HCC patients and served as an independent prognostic marker of overall survival in a multivariable analysis. In addition, through serum starvation and refeeding assay, we demonstrated that Sam68 was lowly expressed in serum-starved HCC cells, and was progressively increased after serum-additioning. Furthermore, siRNA knockdown of endogenous Sam68 inhibited cell proliferation and tumourigenicity of HCC cells in vitro, through blocking the G1 to S phase transition. Moreover, we reported that the anti-proliferative effect of silencing Sam68 was accompanied with up-regulated expression of cyclin-dependent kinase inhibitors, p21(Cip1) and p27(Kip1), enhanced transactivation of FOXO factors (FOXO4), and dysreuglation of Akt/GSK-3β signaling. Taken together, these findings provide a rational framework for the progression of HCC and thereby indicated that Sam68 might be a novel and useful prognostic marker and a potential target for human HCC treatment.

EMT-Inducing Molecular Factors in Gynecological Cancers

Gynecologic cancers are the unregulated growth of neoplastic cells that arise in the cervix, ovaries, fallopian tubes, uterus, vagina, and vulva. Although gynecologic cancers are characterized by different signs and symptoms, studies have shown that they share common risk factors, such as smoking, obesity, age, exposure to certain chemicals, infection with human immunodeficiency virus (HIV), and infection with human papilloma virus (HPV). Despite recent advancements in the preventative, diagnostic, and therapeutic interventions for gynecologic cancers, many patients still die as a result of metastasis and recurrence. Since mounting evidence indicates that the epithelial-mesenchymal transition (EMT) process plays an essential role in metastatic relapse of cancer, understanding the molecular aberrations responsible for the EMT and its underlying signaling should be given high priority in order to reduce cancer morbidity and mortality.

C14ORF166 overexpression is associated with pelvic lymph node metastasis and poor prognosis in uterine cervical cancer

C14ORF166 (chromosome 14 open reading frame 166) is a transcriptional repressor related to the regulation of centrosome architecture. However, the role of C14ORF166 in the development and progression of cancer remains largely unknown. The aim of this study was to investigate the expression and clinicopathological significance of C14ORF166 in cervical cancer. C14ORF166 expression was analyzed using quantitative real-time PCR (RT-PCR) and Western blotting in cervical cancer cell lines and eight paired cervical cancer samples and the adjacent normal tissues. Immunohistochemistry was used to analyze C14ORF166 protein expression in 148 clinicopathologically characterized cervical cancer specimens. Statistical analyses were performed to evaluate the relationship between the expression of C14ORF166 and clinicopathologic features and prognosis. C14ORF166 mRNA and protein expression were significantly upregulated in cervical cancer cell lines and tissue samples (P < 0.05). Immunohistochemical analysis revealed a high expression of C14ORF166 was observed in 39.9 % (59/148) of the cervical cancer specimens; the remaining samples expressed low levels or did not express any detectable C14ORF166. The chi-square test indicated that high-level expression of C14ORF166 was significantly associated with International Federation of Gynecology and Obstetrics (FIGO) stage (P < 0.001), vital status (P = 0.026), tumor size (P = 0.034), serum squamous cell carcinoma antigen level (SCC-Ag; P = 0.035), and pelvic lymph node metastasis (P < 0.001). Patients with highly expressed C14ORF166 showed a tendency to receive postoperative chemotherapy (P = 0.005) and postoperative radiation (P = 0.008). Furthermore, high C14ORF166 expression was associated with poorer overall survival compared to low C14ORF166 expression, and C14ORF166 was a significant prognostic factor in univariate and multivariate analysis (P < 0.05). High C14ORF166 expression had prognostic value for poor outcome in cervical cancer. C14ORF166 may represent a biomarker of pelvic lymph node metastasis and enable the identification of high-risk patients along with selection of appropriate treatment strategies.

SAM68: Signal Transduction and RNA Metabolism in Human Cancer

Alterations in expression and/or activity of splicing factors as well as mutations in cis-acting splicing regulatory sequences contribute to cancer phenotypes. Genome-wide studies have revealed more than 15,000 tumor-associated splice variants derived from genes involved in almost every aspect of cancer cell biology, including proliferation, differentiation, cell cycle control, metabolism, apoptosis, motility, invasion, and angiogenesis. In the past decades, several RNA binding proteins (RBPs) have been implicated in tumorigenesis. SAM68 (SRC associated in mitosis of 68 kDa) belongs to the STAR (signal transduction and activation of RNA metabolism) family of RBPs. SAM68 is involved in several steps of mRNA metabolism, from transcription to alternative splicing and then to nuclear export. Moreover, SAM68 participates in signaling pathways associated with cell response to stimuli, cell cycle transitions, and viral infections. Recent evidence has linked this RBP to the onset and progression of different tumors, highlighting misregulation of SAM68-regulated splicing events as a key step in neoplastic transformation and tumor progression. Here we review recent studies on the role of SAM68 in splicing regulation and we discuss its contribution to aberrant pre-mRNA processing in cancer.

Increased RIPK4 expression is associated with progression and poor prognosis in cervical squamous cell carcinoma patients

Aberrant expression of receptor interacting protein kinase 4 (RIPK4), a crucial regulatory protein of Wnt/β-catenin signaling, has recently been reported to be involved in several cancers. Here, we report the potential clinical implication and biological functions of RIPK4 in cervical squamous cell carcinoma (CSCC). One hundred and ninety-eight CSCC cases, 109 low-grade squamous intraepithelial lesions (LSILs), 141 high-grade squamous intraepithelial lesions (HSILs) and 63 chronic cervicitis were collected. The expression of RIPK4 was detected by immunohistochemistry (IHC), and its clinical value and oncogenic functions were further assessed. RIPK4 expression increased significantly with disease progression from 3.2% in chronic cervicitis, 19.3% in LSILs and 85.1% in HSILs to 94.4% in CSCCs (P < 0.001). Moreover, RIPK4 may serve as a useful biomarker to distinguish HSIL from chronic cervicitis/LSIL, which are two different clinical types for therapeutic procedures, with a high sensitivity and specificity (85.1% and 86.6%, respectively) and the performance improved when combined with p16^INK4a. Further, RIPK4 overexpression was associated with overall (HR = 2.085, P = 0.038) and disease-free survival (HR = 1.742, P = 0.037). Knockdown of RIPK4 reduced cell migration and invasion via inhibition of Vimentin, MMP2 and Fibronectin expression in cervical cancer cells. RIPK4 might act as a potential diagnostic and independent prognostic biomarker for CSCC patients.

MicroRNA-203 inhibits the malignant progression of neuroblastoma by targeting Sam68

Neuroblastoma (NB) is the most common solid extracranial tumor in children. However, the molecular mechanism of NB remains to be elucidated. In the present study, reverse transcription quantitative polymerase chain reaction data demonstrated that the expression of Sam68 was significantly upregulated in NB tissues compared with their matched adjacent normal tissues. Furthermore, it was revealed that reduced expression of miR‑203 and increased expression of Sam68 co‑existed in NB tissues. Knockdown of Sam68 reduced the proliferation, migration and invasion of human SK‑N‑SH and SH‑SY5Y NB cells. Similarly, overexpression of miR‑203 also inhibited the proliferation, migration and invasion of these two cell lines. It was further demonstrated that the protein expression level of Sam68 was negatively mediated by miR‑203 in the SK‑N‑SH and SH‑SY5Y NB cells. Additionally, data from a dual luciferase reporter assay confirmed that miR‑203 directly targeted Sam68 by binding to its 3'‑untranslated region. In conclusion, the present study suggested for the first time, to the best of our knowledge, that the aberrant downregulation of miR‑203 may contribute to the aberrant upregulation of Sam68 in NB and that miR‑203 has an inhibitory role in malignant progression of NB by targeting Sam68. The present study provided evidence to support miR-203/Sam68 as a novel diagnostic or therapeutic targets for NB.

Sam68 promotes cellular proliferation and predicts poor prognosis in esophageal squamous cell carcinoma

Sam68 (Src-associated in mitosis of 68 kD) is a KH domain RNA-binding protein. The expression of Sam68 was correlated with kinds of tumors. Yet, the expression mechanisms and physiological significance of Sam68 in ESCC remains unclear. In this study, we clarified a potential role of Sam68 in the treatment of ESCC. Western blot and immunohistochemistry (IHC) analysis revealed that the protein level of Sam68 was higher in ESCC tumor tissues and cell lines. In addition, IHC stain revealed that Sam68 was positively correlated with clinical pathologic variables such as tumor grade and tumor invasion. In addition, Sam68 could be an independent prognostic indicator for patients' overall survival. In vitro studies such as starvation and refeeding assay along with Sam68-shRNA transfection assay demonstrated that Sam68 expression promoted proliferation of ESCC cells. And Sam68 downregulation caused decreased rate of cell growth and colony formation. Reasons are associated with growth arrest of cell cycle at G1/S phase. Moreover, our results clarified that Sam68 could promote ESCC cell proliferation via the activation of Akt/GSK-3β pathway. This research indicated that Sam68 might accelerate the cell cycle progression and be considered as a new therapy target in ESCC.

Utility of SAM68 in the progression and prognosis for bladder cancer

Background

Muscle invasive bladder cancer (MIBC) is often lethal and non-MIBC (NMIBC) can recur and progress, yet prognostic markers are currently inadequate. SAM68, a member of RNA-binding proteins, has been reported to contribute to progression of other cancers. The aim of this study is to investigate the potential utility of SAM68 in the progression and prognosis of bladder cancer.

Methods

Quantitative PCR and immunohistochemistry were utilized to examine the expression of SAM68 in ten pairs of MIBC and adjacent normal bladder urothelium, and eight pairs of MIBC and non-MIBC (NMIBC) tissues from the same patient. Moreover, SAM68 protein expression level and localization were examined by immunohistochemistry in 129 clinicopathologically characterized MIBC samples. Prognostic associations were determined by multivariable analysis incorporating standard prognostic factors.

Results

SAM68 expression was elevated in MIBC tissues compared with adjacent normal bladder urothelium, and was increased at both transcriptional and translational levels in MIBC tissues compared with NMIBC tissues of the same patient. For MIBC, high expression and nucleus-cytoplasm co-expression of SAM68 were associated with higher T-stage, higher N-stage and worse recurrence-free survival. Five-year recurrence-free survival was 80% and 52.9% for MIBC patients with low and high SAM68 expression, respectively (p = 0.001). SAM68 nucleus-cytoplasm co-expression associated with worse 5-year recurrence-free survival rate (49.2%) than SAM68 expression confined to the nucleus (82.5%) or cytoplasm (75.5%) alone. On multivariable analysis SAM68 expression level, SAM68 nucleus-cytoplasm co-expression, T-stage, and N-stage were all independent prognostic factors for recurrence-free survival of MIBC patients.

Conclusions

SAM68 expression is increased in MIBC when compared to normal urothelium and NMIBC, and appears to be a potentially useful prognostic marker for MIBC.