Long non-coding RNA MALAT1 increases AKAP-9 expression by promoting SRPK1-catalyzed SRSF1 phosphorylation in colorectal cancer cells

M6A-modified lncRNA FAM83H-AS1 promotes colorectal cancer progression through PTBP1

LncRNA plays a crucial role in cancer progression and targeting, but it has been difficult to identify the critical lncRNAs involved in colorectal cancer (CRC) progression. We identified FAM83H-AS1 as a tumor-promoting associated lncRNA using 21 pairs of stage IV CRC tissues and adjacent normal tissues. In vitro and in vivo experiments revealed that knockdown of FAM83H-AS1 in CRC cells inhibited tumor proliferation and metastasis, and vice versa. M6A modification is critical for FAM83H-AS1 RNA stability through the writer METTL3 and the readers IGF2BP2/IGFBP3. PTBP1-an RNA binding protein-is responsible for the FAM83H-AS1 function in CRC. T4 (1770-2440 nt) and T5 (2440-2743 nt) on exon 4 of FAM83H-AS1 provide a platform for PTBP1 RRM2 interactions. Our results demonstrated that m6A modification dysregulated the FAM83H-AS1 oncogenic role by phosphorylated PTBP1 on its RNA splicing effect. In patient-derived xenograft models, ASO-FAM83H-AS1 significantly suppressed the growth of gastrointestinal (GI) tumors, not only CRC but also GC and ESCC. The combination of ASO-FAM83H-AS1 and oxaliplatin/cisplatin significantly suppressed tumor growth compared with treatment with either agent alone. Notably, there was pathological complete response in all these three GI cancers. Our findings suggest that FAM83H-AS1 targeted therapy would benefit patients primarily receiving platinum-based therapy in GI cancers.

AKAP8 promotes ovarian cancer progression and antagonizes PARP inhibitor sensitivity through regulating hnRNPUL1 transcription

Ovarian cancer (OC) is the highest worldwide cancer mortality cause among gynecologic tumors, but its underlying molecular mechanism remains largely unknown. Here, we report that the RNA binding protein A-kinase anchoring protein 8 (AKAP8) is highly expressed in ovarian cancer and predicts poor prognosis for ovarian cancer patients. AKAP8 promotes ovarian cancer progression through regulating cell proliferation and metastasis. Mechanically, AKAP8 is enriched at chromatin and regulates the transcription of the specific hnRNPUL1 isoform. Moreover, AKAP8 phase separation modulates the hnRNPUL1 short isoform transcription. Ectopic expression of the hnRNPUL1 short isoform could partially rescue the growth inhibition effect of AKAP8-knockdown in ovarian cancer cells. In addition, AKAP8 modulates PARP1 expression through hnRNPUL1, and AKAP8 inhibition enhances PAPR inhibitor cytotoxicity in ovarian cancer. Together, our study uncovers the crucial function of AKAP8 condensation-mediated transcription regulation, and targeting AKAP8 could be potential for improvement of ovarian cancer therapy.

Unearthing a novel function of SRSF1 in binding and unfolding of RNA G-quadruplexes

SRSF1 governs splicing of over 1500 mRNA transcripts. SRSF1 contains two RNA-recognition motifs (RRMs) and a C-terminal Arg/Ser-rich region (RS). It has been thought that SRSF1 RRMs exclusively recognize single-stranded exonic splicing enhancers, while RS lacks RNA-binding specificity. With our success in solving the insolubility problem of SRSF1, we can explore the unknown RNA-binding landscape of SRSF1. We find that SRSF1 RS prefers purine over pyrimidine. Moreover, SRSF1 binds to the G-quadruplex (GQ) from the ARPC2 mRNA, with both RRMs and RS being crucial. Our binding assays show that the traditional RNA-binding sites on the RRM tandem and the Arg in RS are responsible for GQ binding. Interestingly, our FRET and circular dichroism data reveal that SRSF1 unfolds the ARPC2 GQ, with RS leading unfolding and RRMs aiding. Our saturation transfer difference NMR results discover that Arg residues in SRSF1 RS interact with the guanine base but not other nucleobases, underscoring the uniqueness of the Arg/guanine interaction. Our luciferase assays confirm that SRSF1 can alleviate the inhibitory effect of GQ on gene expression in the cell. Given the prevalence of RNA GQ and SR proteins, our findings unveil unexplored SR protein functions with broad implications in RNA splicing and translation.

Tumor cell stemness in gastrointestinal cancer: regulation and targeted therapy

The cancer stem cells are a rare group of self-renewable cancer cells capable of the initiation, progression, metastasis and recurrence of tumors, and also a key contributor to the therapeutic resistance. Thus, understanding the molecular mechanism of tumor stemness regulation, especially in the gastrointestinal (GI) cancers, is of great importance for targeting CSC and designing novel therapeutic strategies. This review aims to elucidate current advancements in the understanding of CSC regulation, including CSC biomarkers, signaling pathways, and non-coding RNAs. We will also provide a comprehensive view on how the tumor microenvironment (TME) display an overall tumor-promoting effect, including the recruitment and impact of cancer-associated fibroblasts (CAFs), the establishment of an immunosuppressive milieu, and the induction of angiogenesis and hypoxia. Lastly, this review consolidates mainstream novel therapeutic interventions targeting CSC stemness regulation.

Targeting PRMT1-mediated SRSF1 methylation to suppress oncogenic exon inclusion events and breast tumorigenesis

PRMT1 plays a vital role in breast tumorigenesis; however, the underlying molecular mechanisms remain incompletely understood. Herein, we show that PRMT1 plays a critical role in RNA alternative splicing, with a preference for exon inclusion. PRMT1 methylome profiling identifies that PRMT1 methylates the splicing factor SRSF1, which is critical for SRSF1 phosphorylation, SRSF1 binding with RNA, and exon inclusion. In breast tumors, PRMT1 overexpression is associated with increased SRSF1 arginine methylation and aberrant exon inclusion, which are critical for breast cancer cell growth. In addition, we identify a selective PRMT1 inhibitor, iPRMT1, which potently inhibits PRMT1-mediated SRSF1 methylation, exon inclusion, and breast cancer cell growth. Combination treatment with iPRMT1 and inhibitors targeting SRSF1 phosphorylation exhibits an additive effect of suppressing breast cancer cell growth. In conclusion, our study dissects a mechanism underlying PRMT1-mediated RNA alternative splicing. Thus, PRMT1 has great potential as a therapeutic target in breast cancer treatment.

Unearthing SRSF1's Novel Function in Binding and Unfolding of RNA G-Quadruplexes

SRSF1 governs splicing of over 1,500 mRNA transcripts. SRSF1 contains two RNA-recognition motifs (RRMs) and a C-terminal Arg/Ser-rich region (RS). It has been thought that SRSF1 RRMs exclusively recognize single-stranded exonic splicing enhancers, while RS lacks RNA-binding specificity. With our success in solving the insolubility problem of SRSF1, we can explore the unknown RNA-binding landscape of SRSF1. We find that SRSF1 RS prefers purine over pyrimidine. Moreover, SRSF1 binds to the G-quadruplex (GQ) from the ARPC2 mRNA, with both RRMs and RS being crucial. Our binding assays show that the traditional RNA-binding sites on the RRM tandem and the Arg in RS are responsible for GQ binding. Interestingly, our FRET and circular dichroism data reveal that SRSF1 unfolds the ARPC2 GQ, with RS leading unfolding and RRMs aiding. Our saturation transfer difference NMR results discover that Arg residues in SRSF1 RS interact with the guanine base but other nucleobases, underscoring the uniqueness of the Arg/guanine interaction. Our luciferase assays confirm that SRSF1 can alleviate the inhibitory effect of GQ on gene expression in the cell. Given the prevalence of RNA GQ and SR proteins, our findings unveil unexplored SR protein functions with broad implications in RNA splicing and translation.

SRPKs: a promising therapeutic target in cancer

Cancers such as lung, breast, colon, and prostate have been linked to dysregulation of SRPKs. In preclinical studies, inhibition of SRPKs has been shown to reduce the growth and survival of cancer cells, suggesting that SRPKs may be potential therapeutic targets. Research is ongoing to develop small molecule inhibitors of SRPKs, identify specific SRPKs that are important in different cancer types, and explore the use of RNA interference (RNAi) to target SRPKs. In addition, researchers are examining the potential of using SRPK inhibitors in combination with other cancer therapies, such as chemotherapy or immunotherapy, to improve treatment outcomes. However, more research is needed to fully understand the role of SRPKs in cancer and determine the most effective ways to target them. In the present review, we shed light on the role of SRPKs in most common cancers, its role in cancer resistance, and targeting it for cancer treatment.

MIMT1 and LINC01550 are uncharted lncRNAs down-regulated in colorectal cancer

Incomplete knowledge of the molecular basis of colorectal cancer, with subsequent limitations in early diagnosis and effective treatment, has contributed to this form of malignancy becoming the second most common cause of cancer-related death worldwide. With the advances in high-throughput profiling techniques and the availability of public data sets such as The Cancer Genome Atlas Program (TCGA), a broad range of coding transcripts have been profiled and their underlying modes of action have been mapped. However, there is still a huge gap in our understanding of noncoding RNA dysregulation. To this end, we used a bioinformatics approach to shortlist and evaluate yet-to be-profiled long noncoding RNAs (lncRNAs) in colorectal cancer. We analysed the TCGA RNA-seq data and followed this by validating the expression patterns using a qPCR technique. Analysing in-house clinical samples, the real-time PCR method revealed that the shortlisted lncRNAs, that is MER1 Repeat Containing Imprinted Transcript 1 (MIMT1) and Non-Protein Coding RNA 1550 (LINC01550), were down-regulated in colorectal cancer tumours compared with the paired adjacent normal tissues. Mechanistically, the in silico results suggest that LINC01550 could form a complex competitive endogenous RNA (ceRNA) network leading to the subsequent regulation of colorectal cancer-related genes, such as CUGBP Elav-Like Family Member (CELF2), Polypyrimidine Tract Binding Protein 1 (PTBP1) and ELAV Like RNA Binding Protein 1 (ELAV1). The findings of this work indicate that MIMT1 and LINC01550 could be novel tumour suppressor genes that can be studied further to assess their roles in regulating the cancer signalling pathway(s).

Targeting lncRNAs of colorectal cancers with natural products

Non-coding RNA (ncRNA) is one of the functional classes of RNA that has a regulatory role in various cellular processes, such as modulation of disease onset, progression, and prognosis. ncRNAs, such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), have been actively studied in recent years. The change in ncRNA levels is being actively studied in numerous human diseases, especially auto-immune disorders and cancers; however, targeting and regulating ncRNA with natural products to cure cancer has not been fully established. Recently many groups reported the relationship between ncRNA and natural products showing promising effects to serve as additional therapeutic approaches to cure cancers. This mini-review summarizes the aspects of lncRNAs related to cancer biology focusing on colorectal cancers that natural products can target.

Unraveling the Complex Interactions between the Fat Mass and Obesity-Associated (FTO) Gene, Lifestyle, and Cancer

Carcinogenesis is a complicated process and originates from genetic, epigenetic, and environmental factors. Recent studies have reported a potential critical role for the fat mass and obesity-associated (FTO) gene in carcinogenesis through different signaling pathways such as mRNA N6-methyladenosine (m6A) demethylation. The most common internal modification in mammalian mRNA is the m6A RNA methylation that has significant biological functioning through regulation of cancer-related cellular processes. Some environmental factors, like physical activity and dietary intake, may influence signaling pathways engaged in carcinogenesis, through regulating FTO gene expression. In addition, people with FTO gene polymorphisms may be differently influenced by cancer risk factors, for example, FTO risk allele carriers may need a higher intake of nutrients to prevent cancer than others. In order to obtain a deeper viewpoint of the FTO, lifestyle, and cancer-related pathway interactions, this review aims to discuss upstream and downstream pathways associated with the FTO gene and cancer. The present study discusses the possible mechanisms of interaction of the FTO gene with various cancers and provides a comprehensive picture of the lifestyle factors affecting the FTO gene as well as the possible downstream pathways that lead to the effect of the FTO gene on cancer.

MALAT1 in colorectal cancer: Its implication as a diagnostic, prognostic, and predictive biomarker

Metastasis Associated Lung Adenocarcinoma Transcript 1 (MALAT1), originally described as a prognostic biomarker remarkably linked with metastasis potential in lung cancer, has been identified as contributing to many diseases, including colorectal cancer (CRC). This long non-coding RNA (lncRNA) has come to the forefront of lncRNA research for its implications in cancer-related processes, such as cell proliferation and migration. In general, lncRNAs are recognized as enhancers, scaffolds, or decoys for a variety of oncogenes and tumor suppressors, although our understanding of lncRNA functions and mechanisms of action is still limited. Nowadays, cancer research is attracted to lncRNAs' ability to improve the early diagnosis of cancer, determine patients' prognosis, or predict therapy outcomes. In this review, we aimed to evaluate recent publications trying to uncover the cellular mechanisms of MALAT1-mediated regulation, and its potential exploitation in the management of CRC. The conclusions of this review provide robust support for the essential role of MALAT1 in CRC development and future personalized therapy.

Functional Peptides Encoded by Long Non-Coding RNAs in Gastrointestinal Cancer

Gastrointestinal cancer is by far the most common malignancy and the most common cause of cancer-related deaths worldwide. Recent studies have shown that long non-coding RNAs (lncRNAs) play an important role in the epigenetic regulation of cancer cells and regulate tumor progression by affecting chromatin modifications, gene transcription, translation, and sponge to miRNAs. In particular, lncRNA has recently been found to possess open reading frame (ORF), which can encode functional small peptides or proteins. These peptides interact with its targets to regulate transcription or the signal axis, thus promoting or inhibiting the occurrence and development of tumors. In this review, we summarize the involvement of lncRNAs and the function of lncRNAs encoded small peptides in gastrointestinal cancer.

Metastatic colorectal cancer: Perspectives on long non-coding RNAs and promising therapeutics

Metastatic colorectal cancer (mCRC) has long been lethal despite the continuous efforts of researchers worldwide to discover and improve therapeutic regimens. Thanks to the emergence of long non-coding RNAs (lncRNAs), which has strongly reshaped our inherent perspectives on the pathophysiological patterns of disease, research in the field has been reinvigorated. Here, we focus on current understanding of the modes of action of lncRNAs, and review their regulatory roles in metastatic colorectal cancer, and discuss correlated potential lncRNA-based therapeutics. All of the discussed studies share clear and promising perspectives on future diagnostic and therapeutic remedies for metastatic colorectal cancer.

Keep your eyes peeled for long noncoding RNAs: Explaining their boundless role in cancer metastasis, drug resistance, and clinical application

Cancer metastasis and drug resistance are two major obstacles in the treatment of cancer and therefore, the leading cause of cancer-associated mortalities worldwide. Hence, an in-depth understanding of these processes and identification of the underlying key players could help design a better therapeutic regimen to treat cancer. Earlier thought to be merely transcriptional junk and having passive or secondary function, recent advances in the genomic research have unravelled that long noncoding RNAs (lncRNAs) play pivotal roles in diverse physiological as well as pathological processes including cancer metastasis and drug resistance. LncRNAs can regulate various steps of the complex metastatic cascade such as epithelial-mesenchymal transition (EMT), invasion, migration and metastatic colonization, and also affect the sensitivity of cancer cells to various chemotherapeutic drugs. A substantial body of literature for more than a decade of research evince that lncRNAs can regulate gene expression at different levels such as epigenetic, transcriptional, posttranscriptional, translational and posttranslational levels, depending on their subcellular localization and through their ability to interact with DNA, RNA and proteins. In this review, we mainly focus on how lncRNAs affect cancer metastasis by modulating expression of key metastasis-associated genes at various levels of gene regulation. We also discuss how lncRNAs confer cancer cells either sensitivity or resistance to various chemo-therapeutic drugs via different mechanisms. Finally, we highlight the immense potential of lncRNAs as prognostic and diagnostic biomarkers as well as therapeutic targets in cancer.

MALAT1: A Promising Therapeutic Target for the Treatment of Metastatic Colorectal Cancer

Cancer metastasis research has emerged in recent years as one of the most important topics of debate in the discovery and development of novel anticancer therapies. Colorectal cancer (CRC), the third most common cancer worldwide, has a high mortality rate due to recurrence and distant metastasis to the liver. Several non-coding RNAs (ncRNAs) have been linked to metastatic CRC (mCRC), including the long non-coding RNA (lncRNA) Metastasis-Associated Lung-Adenocarcinoma Transcript 1 (MALAT1). MALAT1 is an RNA that has been linked to tumor cell proliferation, progression, epithelial-mesenchymal transition (EMT), cell migration and invasion, metastasis, and survival in mammalian species. Previously, there was no convincing evidence linking MALAT1 to mCRC. Studies have shown that MALAT1 functions as a competitive endogenous RNA (ceRNA) with microRNAs (miRNAs) and interacts directly with oncogenes and proteins. This RNA also activates several signaling pathways, including Wnt/β-catenin, PI3K/Akt/mTOR, and EMT. Meanwhile, standard chemotherapy and immunotherapy are the current treatment options for mCRC patients. However, evidence-based studies have recently demonstrated that inhibiting the MALAT1 RNA transcript can be considered as a treatment option for mCRC, highlighting the need to investigate its roles as a therapeutic target in mCRC. Thus, in this review, we looked at studies that linked MALAT1 to multiple signaling pathways implicated in mCRC, as well as its potential as a therapeutic target for the treatment of mCRC.

MYH9-dependent polarization of ATG9B promotes colorectal cancer metastasis by accelerating focal adhesion assembly

Tumour metastasis is a major reason accounting for the poor prognosis of colorectal cancer (CRC), and the discovery of targets in the primary tumours that can predict the risk of CRC metastasis is now urgently needed. In this study, we identified autophagy-related protein 9B (ATG9B) as a key potential target gene for CRC metastasis. High expression of ATG9B in tumour significantly increased the risk of metastasis and poor prognosis of CRC. Mechanistically, we further find that ATG9B promoted CRC invasion mainly through autophagy-independent manner. MYH9 is the pivotal interacting protein for ATG9B functioning, which directly binds to cytoplasmic peptide segments aa368-411 of ATG9B by its head domain. Furthermore, the combination of ATG9B and MYH9 enhance the stability of each other by decreasing their binding to E3 ubiquitin ligase STUB1, therefore preventing them from ubiquitin-mediated degradation, which further amplified the effect of ATG9B and MYH9 in CRC cells. During CRC cell invasion, ATG9B is transported to the cell edge with the assistance of MYH9 and accelerates focal adhesion (FA) assembly through mediating the interaction of endocytosed integrin β1 and Talin-1, which facilitated to integrin β1 activation. Clinically, upregulated expression of ATG9B in human CRC tissue is always accompanied with highly elevated expression of MYH9 and associated with advanced CRC stage and poor prognosis. Taken together, this study highlighted the important role of ATG9B in CRC metastasis by promoting focal adhesion assembly, and ATG9B together with MYH9 can provide a pair of potential therapeutic targets for preventing CRC progression.

CCL21 activation of the MALAT1/SRSF1/mTOR axis underpins the development of gastric carcinoma

BACKGROUND

As a significant cause of malignancy mortality, gastric carcinoma (GC) has been well documented to be an often-fatal diagnosis. Despite the limitations of effective therapy, immunotherapy has emerged as a promising therapeutic approach capable of killing cancer cells via the immune system. The current study was conducted to investigate the effect of cytokine C-C motif chemokine ligand 21 (CCL21) on GC progression through the metastasis-associated lung adenocarcinoma transcript 1/serine arginine-rich splicing factor 1/mammalian target of rapamycin (MALAT1/SRSF1/mTOR) axis.

METHODS

Bioinformatics analysis was conducted to identify the key genes associated with GC and to subsequently predict their downstream genes. The effect of CCL21, MALAT1, and SRSF1 on the malignant phenotypes and epithelial-mesenchymal transition (EMT) of SGC-7901 and MGC-803 cells in-vitro and the tumorigenesis of SGC-7901 and MGC-803 cells in-vivo were assessed by expression determination and plasmid transfection. Additionally, RNA pull-down and RNA binding protein immunoprecipitation experiments were performed to determine the MALAT1-microRNA-202-3p (miR-203-3p) interaction and miR-202-3p-SRSF1 interaction followed by the analysis of their effect on the mTOR pathway.

RESULTS

CCL21 was identified as a key GC immune gene. Overexpressed CCL21, MALAT1, and SRSF1 along with poorly expressed miR-202-3p were identified in the GC cells. CCL21 induced the MALAT1 expression in a time- and dose-dependent manner. Functionally, MALAT1 targeted miR-202-3p but upregulated SRSF1 and activated mTOR. Crucially, evidence was obtained indicating that CCL21 promoted both the malignant phenotypes and EMT of SGC-7901 and MGC-803 cells in-vitro and the tumorigenesis of SGC-7901 and MGC-803 cells in-vivo by increasing the MALAT1-induced upregulation of SRSF1.

CONCLUSIONS

Taken together, the key observations of our study provide evidence that CCL21 enhances the progression of GC via the MALAT1/SRSF1/mTOR axis, providing a novel therapeutic target for the treatment of GC.

LINC00963 affects the development of colorectal cancer via MiR-532-3p/HMGA2 axis

Background

LINC00963 is high-expressed in various carcinomas, but its expression and function in colorectal cancer (CRC) have not been explored. This study explored the role and mechanism of LINC00963 in CRC.

Methods

The expression of LINC00963 in CRC and its relationship with prognosis were examined by starBase and survival analysis. The effects of LINC00963, miR-532-3p and HMGA2 on the biological characteristics and EMT-related genes of CRC cells were studied by RT-qPCR, CCK-8, clone formation experiments, flow cytometry, scratch test, Transwell, and Western blot. Xenograft assay and immunohistochemistry were performed to verify the effect of LINC00963 on tumor growth. The correlation among LINC00963, miR-532-3p, and HMGA2 was analyzed by bioinformatics analysis, luciferase assay, and Pearson test.

Results

LINC00963 was high-expressed in CRC, and this was associated with poor prognosis of CRC. Silencing LINC00963 inhibited the activity, proliferation, migration, and invasion of CRC cells, MMP-3 and MMP-9 expressions, moreover, it also blocked cell cycle progression, and inhibited tumor growth and Ki67 expression. However, overexpression of LINC00963 showed the opposite effects to silencing LINC00963. LINC00963 targeted miR-532-3p to regulate HMGA2 expression. Down-regulation of miR-532-3p promoted cell proliferation, migration and invasion, and expressions of MMP-3 and MMP-9, and knockdown of HMGA2 reversed the effect of miR-532-3p inhibitor. Up-regulation of miR-532-3p inhibited the biological functions of CRC cells, and overexpression of HMGA2 reversed the miR-532-3p mimic effect.

Conclusion

LINC00963 affects the development of CRC through the miR-532-3p/HMGA2 axis.

Noncoding RNAs regulate alternative splicing in Cancer

AS (alternative splicing) is a fundamental process by which a gene can generate multiple distinct mRNA transcripts to increase protein diversity. Defects in AS influence the occurrence and development of many diseases, including cancers, and are frequently found to participate in various aspects of cancer biology, such as promoting invasion, metastasis, apoptosis resistance and drug resistance. NcRNAs (noncoding RNAs) are an abundant class of RNAs that do not encode proteins. NcRNAs include miRNAs (microRNAs), lncRNAs (long noncoding RNAs), circRNAs (circular RNAs) and snRNAs (small nuclear RNAs) and have been proven to act as regulatory molecules that mediate cancer processes through AS. NcRNAs can directly or indirectly influence a plethora of molecular targets to regulate cis-acting elements, trans-acting factors, or pre-mRNA transcription at multiple levels, affecting the AS process and generating alternatively spliced isoforms. Consequently, ncRNA-mediated AS outcomes affect multiple cellular signaling pathways that promote or suppress cancer progression. In this review, we summarize the current mechanisms by which ncRNAs regulate AS in cancers and discuss their potential clinical applications as biomarkers and therapeutic targets.

Regulatory Networks of LncRNA MALAT-1 in Cancer

Long noncoding (lnc)RNAs are a group of RNAs with a length greater than 200 nt that do not encode a protein but play an essential role in regulating the expression of target genes in normal biological contexts as well as pathologic processes including tumorigenesis. The lncRNA metastasis-associated lung adenocarcinoma transcript (MALAT)-1 has been widely studied in cancer. In this review, we describe the known functions of MALAT-1; its mechanisms of action; and associated signaling pathways and their clinical significance in different cancers. In most malignancies, including lung, colorectal, thyroid, and other cancers, MALAT-1 functions as an oncogene and is upregulated in tumors and tumor cell lines. MALAT-1 has a distinct mechanism of action in each cancer type and is thus at the center of large gene regulatory networks. Dysregulation of MALAT-1 affects cellular processes such as alternative splicing, epithelial–mesenchymal transition, apoptosis, and autophagy, which ultimately results in the abnormal cell proliferation, invasion, and migration that characterize cancers. In other malignancies, such as glioma and endometrial carcinoma, MALAT-1 functions as a tumor suppressor and thus forms additional regulatory networks. The current evidence indicates that MALAT-1 and its associated signaling pathways can serve as diagnostic or prognostic biomarker or therapeutic target in the treatment of many cancers.

Hypoxia-induced alternative splicing: the 11th Hallmark of Cancer

Hypoxia-induced alternative splicing is a potent driving force in tumour pathogenesis and progression. In this review, we update currents concepts of hypoxia-induced alternative splicing and how it influences tumour biology. Following brief descriptions of tumour-associated hypoxia and the pre-mRNA splicing process, we review the many ways hypoxia regulates alternative splicing and how hypoxia-induced alternative splicing impacts each individual hallmark of cancer. Hypoxia-induced alternative splicing integrates chemical and cellular tumour microenvironments, underpins continuous adaptation of the tumour cellular microenvironment responsible for metastatic progression and plays clear roles in oncogene activation and autonomous tumour growth, tumor suppressor inactivation, tumour cell immortalization, angiogenesis, tumour cell evasion of programmed cell death and the anti-tumour immune response, a tumour-promoting inflammatory response, adaptive metabolic re-programming, epithelial to mesenchymal transition, invasion and genetic instability, all of which combine to promote metastatic disease. The impressive number of hypoxia-induced alternative spliced protein isoforms that characterize tumour progression, classifies hypoxia-induced alternative splicing as the 11th hallmark of cancer, and offers a fertile source of potential diagnostic/prognostic markers and therapeutic targets.

Serine-Arginine Protein Kinase 1 (SRPK1) as a Prognostic Factor and Potential Therapeutic Target in Cancer: Current Evidence and Future Perspectives

Cancer, a heterogeneous disease composed of tumor cells and microenvironment, is driven by deregulated processes such as increased proliferation, invasion, metastasis, angiogenesis, and evasion of apoptosis. Alternative splicing, a mechanism led by splicing factors, is implicated in carcinogenesis by affecting any of the processes above. Accumulating evidence suggests that serine-arginine protein kinase 1 (SRPK1), an enzyme that phosphorylates splicing factors rich in serine/arginine domains, has a prognostic and potential predictive role in various cancers. Its upregulation is correlated with higher tumor staging, grading, and shorter survival. SRPK1 is also highly expressed in the premalignant changes of some cancers, showing a potential role in the early steps of carcinogenesis. Of interest, its downregulation in preclinical models has mostly been tumor-suppressive and affected diverse processes heterogeneously, depending on the oncogenic context. In addition, targeting SRPK1 has enhanced sensitivity to platinum-based chemotherapy in some cancers. Lastly, its aberrant function has been noted not only in cancer cells but also in the endothelial cells of the microenvironment. Although the aforementioned evidence seems promising, more studies are needed to reinforce the use of SRPK1 inhibitors in clinical trials.

Long noncoding MAGI2-AS3 promotes colorectal cancer progression through regulating miR-3163/TMEM106B axis

Colorectal cancer (CRC), is mostly derived from normal colon epithelial cells, and has been reported to be one of most common gastrointestinal malignancies globally. An increasing number of researchers have claimed that long noncoding RNAs (lncRNAs) exert significant functions in tumor progression. Nevertheless, the function of MAGI2-AS3 remains uncertain in CRC. The expression of MAGI2-AS3, miR-3163, and transmembrane protein 106B (TMEM106B) messenger RNA was examined by quantitative real-time polymerase chain reaction. Cell apoptosis was measured by caspase-3 activity test. Cell proliferation was tested by cell-counting kit 8 and 5-ethynyl-2'-deoxyuridine assays. Cell migration was detected by transwell assay. Western blot analysis examined the protein expression of TMEM106B. The expression of Ki-67 was evaluated by immunohistochemistry assay. The binding capacity between miR-3163 and MAGI2-AS3 (or TMEM106B) was studied by radioimmunoprecipitation and luciferase reporter assays. The expression of MAGI2-AS3 and TMEM106B was conspicuously upregulated whereas miR-3163 presented lower expression in CRC cells. MAGI2-AS3 deficiency facilitated cell apoptosis but hampered cell proliferation and migration. MAGI2-AS3 combined with miR-3163 and negatively regulated miR-3163 expression. In addition, the administration of sh-MAGI2-AS3 or miR-3163 mimics suppressed CRC cell growth in vivo. Subsequently, miR-3163 targeted TMEM106B and the transfection of sh-MAGI2-AS3 or miR-3163 mimics downregulated TMEM106B expression. Rescue assays verified that TMEM106B overexpression recovered the effects of MAGI2-AS3 inhibition on cell apoptosis, proliferation, and migration in CRC. MAGI2-AS3 drives CRC progression through regulating miR-3163/TMEM106B axis. This supplies innovative insights on the investigation of molecular mechanism in CRC progression.

MALAT1 rs664589 Polymorphism Inhibits Binding to miR-194-5p, Contributing to Colorectal Cancer Risk, Growth, and Metastasis

Metastasis associated with lung adenocarcinoma transcript-1 (MALAT1) is an evolutionarily highly conserved lncRNA that contributes to colorectal cancer development. However, the exact molecular mechanisms connecting MALAT1 to colorectal cancer have not been fully elucidated. Here, we performed a case-control study in 1,078 patients with colorectal cancer and 1,175 healthy controls to evaluate the association between potentially functional genetic variants of MALAT1 and survival outcomes in patients with colorectal cancer. MALAT1 rs664589 CG/GG genotypes significantly increased the associated risk and decreased overall survival of patients with colorectal cancer compared with the CC genotype. In vitro and in vivo experiments showed that the rs664589 C to G mutation facilitated carcinogenesis and metastasis of colorectal cancer. Mechanistically, the miRNA miR-194-5p targeted MALAT1 for degradation in the nucleus in an Ago2-dependent manner; the rs664589 G allele altered the binding of MALAT1 to miR-194-5p, resulting in increased expression of MALAT1. Colorectal cancer cells and human tissues with the rs664589 CG/GG genotype expressed significantly higher MALAT1 than those with the rs664589 CC genotype. Multivariate Cox regression analysis showed that MALAT1 was a poor prognostic factor of colorectal cancer. In summary, MALAT1 with the rs664589 G allele demonstrates altered binding to miR-194-5p in the nucleus, leading to increased MALAT1 expression and enhanced colorectal cancer development. SIGNIFICANCE: These findings highlight the functional role of MALAT1 polymorphism in colorectal cancer metastasis and survival as well as the underlying mechanism.

Roles of long non-coding RNAs in colorectal cancer tumorigenesis: A Review

Long non-coding RNAs (lncRNAs) are newly identified potential biological and gene regulators. Similar to other cell-free circulating cancer-related nucleic acids, lncRNAs are released in the peripheral circulation of cancer patients and allow for non-invasive gene expression assessment. lncRNAs are considered to be promising biomarkers for cancer prognosis and diagnosis. Several lncRNAs have been found to regulate developmental processes in a number of biological disorders. Recent studies indicated that lncRNAs are associated with numerous diseases, most notably cancer, as they were found to be highly expressed or silenced in a number of human cancers, including colorectal cancer (CRC). Despite advances in the current detection methods, over half of cancer patients succumb to the disease, as several CRC cases are diagnosed at an advanced stage. Due to the lack of non-invasive and low-cost prognostic and diagnostic tests for CRC, the identification of novel, potentially effective biomarkers has been attracting increasing attention in recent cancer research. The present review focused on the most widely applied lncRNAs in cancer detection, including CRC, in vitro.

Long noncoding RNA MALAT1 mediates stem cell-like properties in human colorectal cancer cells by regulating miR-20b-5p/Oct4 axis

Cancer stem cells (CSCs) are crucial components of the tumor microenvironment that take part in tumor initiation, progression, recurrence, metastasis, and resistance to chemotherapy. This study explores the mechanisms through which CSCs maintain their stemness, especially in tumors of colorectal cancer (CRC), which thus far remain uncertain. Our findings indicated that the expression of miR-20b-5p is negatively correlated with that of metastasis-associated lung adenocarcinoma transcript-1 (MALAT1, r = -0.928, p = 0.023) and Oct4 (r = -0.894, p = 0.041) in CRC cells. We hypothesized that there may be some targeted regulatory relationships among MALAT1, miR-20b-5p, and Oct4. We proceeded to show that both si-MALAT1 and miR-20b-5p-mimic attenuated microsphere formation and self-renewal capacity, decreased the proportion of CSCs, and downregulated the expression of proteins associated with tumor cell stemness maintenance (Oct4, Nanog, sex-determining region Y-box 2, and Notch1) and cellular metabolism (glucose transporter 1, lactate dehydrogenase B, hexokinase 2, and pyruvate kinase isozyme M2) in HCT-116 cells in vitro. In addition, a xenograft model based on Balb/c mice demonstrated that the administration of either si-MALAT1 or miR-20b-5p-mimic suppressed the tumorigenicity of HCT-116 cells in vivo. The underlying mechanisms may involve the targeting of the tumor cell stemness maintenance-related factor Oct4 by miR-20b-5p. For the first time, we present the possible underlying effects of MALAT1 in influencing the stem cell-like properties of CRC cells. We propose that microRNAs and long noncoding RNAs have vital functions in mediating tumor stemness, which remain to be fully elucidated.

Emerging role of long non-coding RNA MALAT1 in predicting clinical outcomes of patients with digestive system malignancies: A meta-analysis

Digestive system malignancies are the most common cancer types worldwide and exhibit an extremely low overall 5-year survival rate. Therefore, clinically applicable biomarkers for predicting clinical outcome are urgently required. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is abnormally expressed in several cancer types. However, to the best of our knowledge, the association between MALAT1 expression and the prognosis of digestive system malignancies remains unknown. Therefore, the current study performed a meta-analysis to comprehensively summarize the association between MALAT1 expression and digestive system malignancies. A total of 1,157 Asian patients from 12 eligible studies [eight studies that investigated overall survival (OS), two studies that investigated disease-free survival and two studies that investigated both indicators] were analyzed. The present results identified a significant association between MALAT1 abundance and poor OS in patients with digestive system malignancies, with a pooled hazard ratio (HR) of 1.62 [95% confidence interval (CI), 1.35–1.88; P<0.001]. The tumor type, region, sample size and analysis type did not alter the predictive value of MALAT1 as an independent factor for survival. Furthermore, MALAT1 overexpression was an unfavorable prognostic factor for the overall survival of patients with esophageal carcinoma, pancreatic cancer, hepatocellular carcinoma and gastric cancer, with HRs of 1.89 (95% CI, 1.29–2.49), 1.76 (95% CI, 0.89–2.63), 1.46 (95% CI, 0.76–2.17) and 1.41 (95% CI, 1.04–1.78), respectively. In particular, increased MALAT1 expression levels were significantly associated with decreased OS in patients with colorectal cancer (HR, 3.04; 95% CI, 1.77–4.31). In conclusion, lncRNA MALAT1 may be a potential prognostic factor for digestive system malignancies in Asian populations.

The novel long non‑coding RNA PRNCR1‑2 is involved in breast cancer cell proliferation, migration, invasion and cell cycle progression

Long non‑coding RNAs (lncRNAs) have recently been reported to act as important mediators of tumor initiation and progression. The present study aimed to investigate the expression and pathogenic roles of the lncRNA prostate cancer‑associated non‑coding RNA (PRNCR)1‑2 in breast cancer. The expression levels of PRNCR1‑2 were detected in breast cancer tissues and numerous breast cancer cell lines using reverse transcription‑quantitative polymerase chain reaction. Depletion of PRNCR1‑2 expression in breast cancer cells was conducted through small interfering RNA‑mediated silencing. Subsequently, cell proliferation was assessed by MTS assay, cell migration and invasion capacities were evaluated using the Transwell culture system, and cell cycle progression and apoptosis were analyzed by flow cytometry. Protein expression levels of the signaling components checkpoint kinase 2 (CHK2), protein kinase B (AKT), phosphorylated (p)‑CHK2 and p‑AKT were measured by western blotting. The results demonstrated that PRNCR1‑2 expression was significantly elevated in breast cancer tissues compared with in adjacent normal tissues. Furthermore, depletion of PRNCR1‑2 in HS‑578T and MDA‑MB‑231 breast cancer cells markedly suppressed their proliferation rates, migration and invasion capacities, and cell cycle progression; however, it had no effect on cell apoptosis. In addition, PRNCR1‑2 depletion increased CHK2 phosphorylation and decreased AKT phosphorylation in HS‑578T and MDA‑MB‑231 cells. In conclusion, the lncRNA PRNCR1‑2 may promote breast cancer cell proliferation, migration, invasion and cell cycle progression.

The long noncoding RNA MALAT-1 functions as a competing endogenous RNA to regulate MSL2 expression by sponging miR-338-3p in myasthenia gravis

Myasthenia gravis (MG) is a cell-dependent autoimmune disease commonly associated with thymic pathology. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT-1) has been associated with gene regulation and alternative splicing. It has shown relationship with proliferation, apoptosis, migration, and invasion. In this study, we found that MALAT-1 expression was downregulated in MG. The level of the miR-338-3p was increased in peripheral blood mononuclear cells from MG patients compared with those from control subjects. MALAT-1 competed for binding to miR-338-3p with male-specific lethal 2 (MSL2) in luciferase reporter assays. We confirmed the MALAT-1-miR-338-3p-MSL2 interaction network in MG in vitro. Thus, MALAT-1 directly induced MSL2 expression in MG by acting as a competing endogenous RNA for miR-338-3p, suggesting that it may serve as a therapeutic target for MG treatment.

High expression of long non-coding RNA MALAT1 in breast cancer is associated with poor relapse-free survival

PURPOSE

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been identified as a prognostic marker for the metastasis of early-stage non-small cell lung cancer (NSCLCs). We studied MALAT1 expression in breast cancer in relation to disease features and patient survival.

METHODS

Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to measure MALAT1 expression in tumor samples of 509 breast cancer patients. Hazards ratios (HRs) and 95% confidence intervals (CIs) were calculated to assess the association between MALAT1 expression and breast cancer survival using the Cox proportional hazards regression model, and the analysis was adjusted for age at surgery, tumor grade, disease stage, and hormone receptor status. Meta-analysis of multiple microarray datasets from online databases and our own study was performed to evaluate the association of MALAT1 with breast cancer survival.

RESULTS

Patients with low-grade or ER-positive tumors had higher expression of MALAT1 compared to those with high-grade (p = 0.013) or ER-negative (p = 0.0002) tumors. Patients with PR-positive tumors also had higher MALAT1 expression than those with PR-negative tumors (p < 0.0001). In patients with positive hormone receptors or low tumor grade, tumors with high MALAT1 expression were more likely to recur. Survival analysis showed that patients with high expression of MALAT1 had a twofold increase in risk of relapse (p = 0.0083) compared to those with low expression. This association remained significant after adjustment for age at surgery, disease stage, tumor grade, and hormone receptor status. Meta-analysis showed that high MALAT1 expression was associated with poor relapse-free survival in patients with hormone receptor-positive tumors (HR 1.44, 95% CI 1.08-1.92).

CONCLUSIONS

High expression of lncRNA MALAT1 is associated with breast cancer relapse and may play a role in tumor progression.

MALAT1-miR663a negative feedback loop in colon cancer cell functions through direct miRNA-lncRNA binding

The lncRNA MALAT1 has multiple biological functions, including influencing RNA processing, miRNA sponging, and cancer development. It is acknowledged that miR663a and its targets are inflammation-related genes frequently deregulated in many cancers. The associations between MALAT1 and miR663a and their target genes remain unknown. In this study, it was found that in colon cancer (CC) cells, MALAT1 and miR663a were reciprocally repressed in cDNA array screening and qRT-PCR analysis. However, MALAT1 was significantly upregulated in CC tissues, and miR663a was significantly downregulated relative to the corresponding surgical margin (SM) tissues. An inverse relationship between MALAT1 and miR663a expression was detected among CC tissue samples (n = 172, r = -0.333, p < 0.0001). The RNA-pulldown results showed MALAT1 lncRNA-miR663a binding. The results of luciferase-reporter analysis further revealed that the MALAT1 7038-7059 nt fragment was the miR663a seed sequence. Both miR663a knockdown and MALAT1 activation alone significantly upregulated the expression levels of miR663a targets, including TGFB1, PIK3CD, P53, P21, and JUND, in the CC cell lines HCT116 and SW480. A positive relationship was also observed between the expression levels of MALAT1 and these miR663a targets in the above 172 CC samples and 160 CC samples in publicly available databases. In addition, reciprocal abolishment of the effects of miR663a overexpression and MALAT1 activation on the proliferation, migration, and invasion of cancer cells was also observed, while miR663a upregulation and MALAT1 activation alone inhibited and promoted the behaviors of these CC cell lines, respectively. All these suggested that, as a competing endogenous lncRNA, MALAT1 maybe a dominant protector for the degradation of miR663a targets. miR663a and MALAT1 may consist of a negative feedback loop to determine their roles in CC development.

LncRNA CDKN2B-AS1 promotes tumor growth and metastasis of human hepatocellular carcinoma by targeting let-7c-5p/NAP1L1 axis

Long non-coding RNAs (lncRNAs) show great potential as therapeutic targets in many diseases including hepatocellular carcinoma (HCC). Here, we aimed to investigate the clinical significance and function of lncRNA CDKN2B antisense RNA 1 (CDKN2B-AS1) in HCC. Here, we identified a novel oncogenic lncRNA CDKN2B-AS1, which was highly expressed in HCC and positively associated with large tumor size, microvascular invasion, high tumor grade, advanced tumor stage and reduced survival of HCC patients. CDKN2B-AS1 knockdown inhibited cell proliferation, migration and invasion, and induced G1 arrest and apoptosis of HCC cells in vitro, and CDKN2B-AS1 silencing suppressed tumor growth and metastasis of HCC in vivo. In accordance, CDKN2B-AS1 overexpression accelerated HCC cell growth and metastasis. Mechanistically, CDKN2B-AS1 promoted nucleosome assembly protein 1 like 1 (NAP1L1) expression by sponging let-7c-5p, thereby activated PI3K/AKT/mTOR signaling in HCC cells. Notably, NAP1L1 restoration abolished the effects of CDKN2B-AS1 silencing on HCC cell growth and metastasis. CDKN2B-AS1, an oncogenic lncRNA of HCC, promoted NAP1L1-mediated PI3K/AKT/mTOR signaling by acting as a molecular sponge of let-7c-5p. Our findings indicate that CDKN2B-AS1 may be a potential prognostic biomarker and a candidate target for HCC therapy.

LncRNAs act as prognostic and diagnostic biomarkers in renal cell carcinoma: a systematic review and meta-analysis

We conducted a systematic review and meta-analysis to investigate the clinical values, including clinicopathology, prognosis, and diagnosis of different long non-coding RNAs (lncRNAs) in renal cell carcinoma (RCC). A total of 14 eligible studies, including 10 on clinicopathological features, 11 on prognosis, and 3 on diagnosis were identified. Results revealed that metastasis-associated lung adenocarcinoma transcript 1(MALAT1) expression was associated with tumor stage (odds ratio [OR], 3.46; 95% confidence interval [CI], 1.63-7.36; p=0.001). The high expression of MALAT1 could be considered a biomarker of the early detection of lymph node metastasis and predictor of poor survival in RCC patients, who likely manifested short overall survival (OS; hazard ratio [HR], 2.97; 95% CI, 1.68-5.28; p<0.001). For diagnostic value, the pooled result showed that lncRNA maintained a sensitivity of 0.89 and specificity of 0.91 in RCC diagnosis, The area under the curve of 0.94 (95% CI, 0.92-0.96) for lncRNA in RCC diagnosis also indicated a significant advantage over other biomarkers. Our systematic review and meta-analysis demonstrated that lncRNAs could be considered biomarkers to detect lymph node metastasis and distant metastasis in early stages. LncRNAs could function as potential prognostic markers in RCC. LncRNAs could also display high accuracy for RCC diagnosis.

Long noncoding RNA LINC01510 promotes the growth of colorectal cancer cells by modulating MET expression

Background

Abnormal expression of long non-coding RNA (lncRNAs) often facilitates unrestricted growth of cancer cells. Long intergenic non-protein coding RNA 1510, an enhancer lncRNA (LINC01510), a lncRNA enhancer is upregulated in colorectal cancer (CRC), and its expression might relate to MET as revealed by lncRNA microarray data. However, the potential biological role of LINC01510 and its regulatory mechanism in CRC remain unclear. Therefore, we investigated the involvement of LINC01510 in the proliferation of CRC cells.

Methods

Microarray analysis, In situ hybridization, colony formation assay, MTT assay, Western blotting, quantitative RT-PCR and flow cytometry were applied. The two-tailed Student’s t test and analysis of variance or general linear model of single factor variable was used for statistical analyse.

Results

In the present study, we found that LINC01510 was significantly upregulated in CRC tissues and cell lines. The LINC01510 expression level were associated with the clinicopathological grade and stage. Meanwhile, gain- and loss-of-function assays demonstrated that LINC01510 overexpression increased CRC cell proliferation, and promoted cell cycle progression from the G1 phase to the S phase. Further study indicated that LINC01510 was positively correlated with the expression of MET, and its effects were most likely at the transcriptional level.

Conclusions

Taken together, our findings suggested that upregulation of LINC01510 contributes to the proliferation of CRC cells, at least in part, through the regulation of MET protein. LINC01510 could be a candidate prognostic biomarker and a target for new therapies in CRC patients.

SRPK1‑siRNA suppresses K562 cell growth and induces apoptosis via the PARP‑caspase3 pathway

Serine-arginine protein kinase 1 (SRPK1) has been used as an important signal mediator, and is associated with cancer development. However, studies have yet to determine whether SRPK1 suppresses leukemia cell growth and induces apoptosis. Studies have also yet to reveal the underlying mechanisms. In the present study, the effects of downregulating SRPK1 gene expression on chronic myeloid leukemia cell lines (K562 cells) were investigated through RNA interference (RNAi) and the proliferation inhibition and apoptosis induction of SRPK1 in K562 cells were analyzed. K562 cells were transfected with two different concentrations of siRNA, and the transfection efficiency was detected via flow cytometry. The expression of SRPK1 was detected via reverse transcription‑quantitative polymerase chain reaction. K562 cell proliferation and apoptosis were analyzed using MTT and flow cytometry respectively. The roles of caspase‑3, poly (ADP‑ribose) polymerase (PARP), p53 and B-cell lymphoma (Bcl)‑2/Bcl‑2 associated X, apoptosis regulator (Bax) proteins in the apoptosis of human K562 cells were further examined through western blot analysis. The SRPK1 expression was lower in the K562 cells transfected with SRPK1‑siRNA compared with untransfected cells. The inhibition rate in the transfected groups was increased compared with the untransfected groups. Compared with control groups, the number of apoptotic cells in the SRPK1‑silenced groups increased. The number of early apoptotic cells also increased. The cleaved caspase‑3, cleaved PARP and p53 expression levels were significantly increased in the RNAi groups compared with control groups. Conversely, the Bcl‑2/Bax rate was significantly lower. In conclusion, the knockdown of the SRPK1 gene by RNAi inhibited the proliferation of K562 cells and induced their apoptosis. Apoptosis was induced by the activation of the PARP‑caspase3 pathway.

LncRNAs: the bridge linking RNA and colorectal cancer

Long noncoding RNAs (lncRNAs) are transcribed by genomic regions (exceeding 200 nucleotides in length) that do not encode proteins. While the exquisite regulation of lncRNA transcription can provide signals of malignant transformation, lncRNAs control pleiotropic cancer phenotypes through interactions with other cellular molecules including DNA, protein, and RNA. Recent studies have demonstrated that dysregulation of lncRNAs is influential in proliferation, angiogenesis, metastasis, invasion, apoptosis, stemness, and genome instability in colorectal cancer (CRC), with consequent clinical implications. In this review, we explicate the roles of different lncRNAs in CRC, and the potential implications for their clinical application.

DNA-methylation-mediated repression of miR-766-3p promotes cell proliferation via targeting SF2 expression in renal cell carcinoma

Aberrant expression of microRNA (miRNA) emerges as an important role in a wide range of human malignances, and further identification as well as validation of the change of these endogenous non-protein-coding transcripts is warranted. Here, we identify a novel epigenetic regulation of miR-766-3p and investigate its biological function as well as clinical significance in renal cell carcinoma (RCC). Bisulfate analysis elucidates that the promoter of miR-766-3p is highly methylated in RCC tissues compared to non-tumorous tissues. Notably, the downregulation of miR-766-3p is obviously associated with clinical stage and worse prognosis in RCC patients. Upregulated miR-766-3p attenuates cell-cycle progression via targeting SF2 expression and additional SF2/P-AKT/P-ERK signaling pathway. Moreover, high level of SF2, as a novel oncoprotein in RCC, was significantly associated with poor survival in a large cohort of RCC specimens. Taken together, our study presents a road map for the prediction and validation of miR-766-3p/SF2 axis and thus imparts a therapeutic way for further RCC progression.

The long non-coding RNA MALAT1 promotes the migration and invasion of hepatocellular carcinoma by sponging miR-204 and releasing SIRT1

Increasing evidence supports the significance of long non-coding RNA in cancer development. Several recent studies suggest the oncogenic activity of long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in hepatocellular carcinoma. In this study, we explored the molecular mechanisms by which MALAT1 modulates hepatocellular carcinoma biological behaviors. We found that microRNA-204 was significantly downregulated in sh-MALAT1 HepG2 cell and 15 hepatocellular carcinoma tissues by quantitative real-time polymerase chain reaction analysis. Through bioinformatic screening, luciferase reporter assay, RNA-binding protein immunoprecipitation, and RNA pull-down assay, we identified microRNA-204 as a potential interacting partner for MALAT1. Functionally, wound-healing and transwell assays revealed that microRNA-204 significantly inhibited the migration and invasion of hepatocellular carcinoma cells. Notably, sirtuin 1 was recognized as a direct downstream target of microRNA-204 in HepG2 cells. Moreover, si-SIRT1 significantly inhibited cell invasion and migration process. These data elucidated, by sponging and competitive binding to microRNA-204, MALAT1 releases the suppression on sirtuin 1, which in turn promotes hepatocellular carcinoma migration and invasion. This study reveals a novel mechanism by which MALAT1 stimulates hepatocellular carcinoma progression and justifies targeting metastasis-associated lung adenocarcinoma transcript 1 as a potential therapy for hepatocellular carcinoma.

Long Non-Coding RNA MALAT1 Interacts With miR-204 to Modulate Human Hilar Cholangiocarcinoma Proliferation, Migration, and Invasion by Targeting CXCR4

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is involved in the development and progression of many types of tumors. An aberrant expression of MALAT1 was observed in many kinds of cancers. However, the exact effects and molecular mechanisms of MALAT1 in human hilar cholangiocarcinoma (HCCA) progression are still unknown. Here, we investigated the role of MALAT1 in human HCCA cell lines and clinical tumor samples in order to determine the function of this lncRNA. In our research, lncRNA-MALAT1 was specifically upregulated in HCCA tissues and cell lines, and was associated with pathological T stage, a larger tumor size, and perineural invasion. Knockdown of MALAT1 inhibited the proliferation, migration, and invasion of human HCCA cell. In addition, chemokine receptor-4 (CXCR4) was involved in MALAT1 induced human HCCA growth, migration, and invasion. By using online tools and a series of mechanistic analysis, we also demonstrated that miR-204-dependent CXCR4 regulation was required in MALAT1 modulating HCCA cell growth, migration and invasion. Taken together, our data indicated that MALAT1 might play an oncogenic role in HCCA through miR-204-dependent CXCR4 regulation, and could be regarded as a therapeutic target in HCCA. J. Cell. Biochem. 118: 3643-3653, 2017. © 2017 Wiley Periodicals, Inc.

Serine-arginine protein kinase 1 (SRPK1) is elevated in gastric cancer and plays oncogenic functions

Serine-arginine protein kinase 1 (SRPK1) phosphorylates proteins involved in the regulation of several mRNA processing pathways including alternative splicing. SRPK1 has been reported to be over-expressed in multiple cancers including prostate, breast, lung and glioma. Several studies further identified that inhibition of SRPK1 showed tumor-suppressive effects, thus raising SRPK1 as a novel candidate chemotherapy target. Interestingly, SRPK1 plays tumor suppressing role in mouse embryonic fibroblasts, on that SRPK1-silencing induces cell transformation. Therefore, the effect of SRPK1 seems heterogeneously in different cell types and tissues. The existence and role of SRPK1 in gastric cancer (GC) hasn't been reported. Here we investigated the expression pattern of SRPK1 in GC by immunohistochemistry and found that it was up-regulated in tumor tissues, where its expression was correlated with tumor grade and prognosis. Further, we explored the signaling mechanism of SRPK1 in promoting GC progression, which revealed that both PP2A and DUSP6 phosphatases impaired the oncogenic effects of SRPK1. However, we didn't find any direct interaction between SRPK1 with PP2A or DUSP6, indicating PP2A and DUSP6 function by regulating the downstream effectors of SRPK1. Our study not only revealed the clinical significance of SRPK1 in GC, but also provided new evidence for its signaling modulation which is invaluable for novel chemotherapy development.

Development of In Silico Protocols to Predict Structural Insights into the Metabolic Activation Pathways of Xenobiotics

To establish in silico model to predict the structural insight into the metabolic bioactivation pathway of xenobiotics, we considered two specific and one non-specific mammary procarcinogen [e.g., dibenzo[a,l]pyrene (DBP), 7,12-dimethylbenz[a]anthracene (DMBA), and benzo[a]pyrene (BP)]. The CYP1A1, 1B1, 2C9, 1A2 and 2B6 reported in wet-lab studies to actively metabolize DBP also showed strong binding energies (kcal/mol) of -11.50, -10.67, -10.37, -9.76 and -9.72, respectively, with inhibition constants ranging between 0.01 and 0.08 µM. The CYP3A4 depicted minimum binding energy (-9.51 kcal/mol) which is in agreement with the wet-lab reports. Further, relatively better affinity of CYP1A1 and CYP1B1 with the dibenzo[a,l]pyrene-11,12-diol (DBPD) might be indicative of their involvement in carcinogenicity of parent compound. Like DBP, BP (-10.13 kcal/mol, Ki: 0.04 µM) and BP-diols (BPD) (-9.01 kcal/mol, Ki: 0.25 µM) observed plausible binding with CYP1A1 supporting to the reported data that emphasize the major contribution of CYP1A1 in the activation of similar procarcinogens and mutagens. Likewise, in silico results further highlighted the CYP1A1 as key player in bioactivation of DMBA to its carcinogenic metabolites. In case of PhIP metabolism, strong binding interaction predicted with CYP1A1 (-9.63 kcal/mol) rather than CYP1A2 (-8.84 kcal/mol). Dissimilarity in the binding affinity of PhIP might be due to its basic scaffold. Further, molecular dynamics (MD) simulation of 10 ns has been revealed that docked complexes of CYP1A1 with DBP, DMBA and BP are comparatively more stable than the complex of PhIP. Moreover, the current findings might be valuable as reference model in prediction and elucidation of the approximate metabolic pathway of xenobiotics.

High Expression of Long Noncoding RNA MALAT1 Indicates a Poor Prognosis and Promotes Clinical Progression and Metastasis in Bladder Cancer

BACKGROUND

Recent studies have demonstrated that the expression of long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) promotes cancer cell proliferation, invasion, and metastasis in many tumor types, but the association between bladder cancer and MALAT1 remains unknown.

MATERIALS

The expression of MALAT1 was tested by in situ hybridization (ISH) in 120 bladder cancer specimens. The association between MALAT1 expression and clinicopathological features and prognosis of the patients with bladder cancer was analyzed. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to verify the relationship between the expression of MALAT1 and progression and metastasis of bladder cancer.

RESULTS

ISH showed that high MALAT1 expression was associated with advanced histological grade, high tumor stage, and positive lymph nodes. Kaplan-Meier survival analysis and Cox regression analysis indicated that high tumor stage, positive lymph nodes, and high MALAT1 expression were independent prognostic indicators for overall survival (OS) of patients with bladder cancer. qRT-PCR showed that the expression of MALAT1 in bladder cancer tissues was 2.85 times higher than those measured in adjacent normal tissues (P < .001). The expression of MALAT1 was 2.673 ± 0.254 in non-muscle-invasive bladder cancer and 2.987 ± 0.381 in muscle-invasive bladder cancer (P = .018). In bladder cancer specimens with positive lymph nodes, MALAT1 expression was 3.167 ± 0.297 versus 2.896 ± 0.329 in bladder cancer specimens with negative lymph nodes (P = .020).

CONCLUSION

High MALAT1 expression could serve as an independent prognostic factor for OS of patients with bladder cancer and could be considered as a potential therapeutic target of bladder cancer.

Long non-coding RNA MALAT1 drives gastric cancer progression by regulating HMGB2 modulating the miR-1297

Background

Emerging evidences have verified that long non-coding RNAs (lncRNAs) play important regulatory roles in the pathogenesis and progression of cancers. lncRNAs metastasis associated lung adenocarcinoma transcript 1 (MALAT1) have been found to be up-regulated in some human cancers. The main objective of this study was to investigate the expression level and biological function of MALAT1 in gastric cancer (GC).

Methods

Quantificational real-time polymerase chain reaction (qRT-PCR) was performed to detect the mRNA levels of MALAT1 in 78 paired gastric carcinoma tissues and adjacent normal tissues, and the associations of MALAT1 expression with the clinicopathological features were analyzed, and the prognosis of gastric carcinoma patients was evaluated. The HMGB2 mRNA and protein expressions were detected by qRT-PCR and western-blot analysis. Luciferase reporter assay was used to determine miR-1297 was a target of MALAT1.

Results

In this study, we demonstrated MALAT1 was up-regulation in GC tissues compared with adjacent normal tissues and higher MALAT1 expression was correlated with local invasion, lymph node metastasis and TNM stage. Patients with higher MALAT1 expression predicted a shorter survival and poor prognosis. Functionally, we revealed that MALAT1 promoted cells proliferation and invasion in GC. Mechanistically, our results demonstrated that MALAT1 was negatively correlation with miR-1297 and functioned as a molecular sponging miR-1297, antagonizing its ability to suppress HMGB2 expression.

Conclusions

Taken together, these results demonstrated that MALAT1/miR-1297/HMGB2 axis acted as critical regulator pathway in GC tumorigenesis and progression, which provided a novel therapeutic target for gastric cancer.

Noncoding RNAs in the development, diagnosis, and prognosis of colorectal cancer

More than 90% of the human genome is actively transcribed, but less than 2% of the total genome encodes protein-coding RNA, and thus, noncoding RNA (ncRNA) is a major component of the human transcriptome. Recently, ncRNA was demonstrated to play important roles in multiple biological processes by directly or indirectly interfering with gene expression, and the dysregulation of ncRNA is associated with a variety of diseases, including cancer. In this review, we summarize the function and mechanism of miRNA, long intergenic ncRNA, and some other types of ncRNAs, such as small nucleolar RNA, circular ncRNA, pseudogene RNA, and even protein-coding mRNA, in the progression of colorectal cancer (CRC). We also presented their clinical application in the diagnosis and prognosis of CRC. The summary of the current state of ncRNA in CRC will contribute to our understanding of the complex processes of CRC initiation and development and will help in the discovery of novel biomarkers and therapeutic targets for CRC diagnosis and treatment.