MicroRNA-135b regulates metastasis suppressor 1 expression and promotes migration and invasion in colorectal cancer

MicroRNA-135b mainly functions as an oncogene during tumor progression

Late diagnosis is considered one of the main reasons of high mortality rate among cancer patients that results in therapeutic failure and tumor relapse. Therefore, it is needed to evaluate the molecular mechanisms associated with tumor progression to introduce efficient markers for the early tumor detection among cancer patients. The remarkable stability of microRNAs (miRNAs) in body fluids makes them potential candidates to use as the non-invasive tumor biomarkers in cancer screening programs. MiR-135b has key roles in prognosis and survival of cancer patients by either stimulating or inhibiting cell proliferation, invasion, and angiogenesis. Therefore, in the present review we assessed the molecular biology of miR-135b during tumor progression to introduce that as a novel tumor marker in cancer patients. It has been reported that miR-135b mainly acts as an oncogene by regulation of transcription factors, signaling pathways, drug response, cellular metabolism, and autophagy. This review paves the way to suggest miR-135b as a tumor marker and therapeutic target in cancer patients following the further clinical trials and animal studies.

MiRNA-related metastasis in oral cancer: moving and shaking

Across the world, oral cancer is a prevalent tumor. Over the years, both its mortality and incidence have grown. Oral cancer metastasis is a complex process involving cell invasion, migration, proliferation, and egress from cancer tissue either by lymphatic vessels or blood vessels. MicroRNAs (miRNAs) are essential short non-coding RNAs, which can act either as tumor suppressors or as oncogenes to control cancer development. Cancer metastasis is a multi-step process, in which miRNAs can inhibit or stimulate metastasis at all stages, including epithelial-mesenchymal transition, migration, invasion, and colonization, by targeting critical genes in these pathways. On the other hand, long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), two different types of non-coding RNAs, can regulate cancer metastasis by affecting gene expression through cross-talk with miRNAs. We reviewed the scientific literature (Google Scholar, Scopus, and PubMed) for the period 2000-2023 to find reports concerning miRNAs and lncRNA/circRNA-miRNA-mRNA networks, which control the spread of oral cancer cells by affecting invasion, migration, and metastasis. According to these reports, miRNAs are involved in the regulation of metastasis pathways either by directly or indirectly targeting genes associated with metastasis. Moreover, circRNAs and lncRNAs can induce or suppress oral cancer metastasis by acting as competing endogenous RNAs to inhibit the effect of miRNA suppression on specific mRNAs. Overall, non-coding RNAs (especially miRNAs) could help to create innovative therapeutic methods for the control of oral cancer metastases.

Effect of the MiR-99b and MiR-135b on peritoneal carcinomatosis and liver metastasis in colorectal cancer

AIM

This study aimed to evaluate the expression levels of miR-99b and miR-135b in peritoneal carcinoma and liver metastases associated with Colorectal Cancer (CRC), assess their association with the intracellular signaling pathway proteins Kirsten Rat Sarcoma Virus (KRAS) and Akt, and investigate their effects on survival.

MATERIALS AND METHODS

Changes in the KRAS gene and Akt proteins, expression levels of miR-99b and miR-135b, and factors affecting survival were compared between colorectal cancer-associated peritoneal carcinomatosis and liver metastasis.

RESULTS

The expression levels of miR-99b and miR-135b and the immunohistochemical grade classification score of Akt were higher in colorectal cancer, peritoneal carcinomatosis, and liver metastasis than in normal tissues (p < 0.05). MiR-99b expression was highest in CRC, whereas miR-135b expression was highest in peritoneal carcinomatosis (p < 0.05). The expression level of miR-99b decreased and that of miR-135b increased in peritoneal and liver metastases compared with that in the tumor tissue. MiR-99b, Akt, and recurrence were risk factors that affected the overall survival rate in the model of clinical predictions (p = 0.045, p = 0.006, and p = 0.012, respectively).

CONCLUSION

While the expression of miR-99b was highest in the primary tumor, its decrease in liver metastasis and peritoneal carcinomatosis suggests that miR-99b has a protective effect against liver metastasis and peritoneal carcinomatosis. However, the detection of miR-135b expression was highest in peritoneal carcinomatosis and liver metastasis compared with that in the colorectal cancer tissues suggesting that it facilitates peritoneal carcinomatosis and liver metastasis. Furthermore, miR-99b, KRAS mutations, and Akt are risk factors for the overall survival of colorectal cancer.

Differentially Deregulated MicroRNAs as Novel Biomarkers for Neoplastic Progression in Ulcerative Colitis

INTRODUCTION

Colorectal cancer (CRC) is a potentially life-threatening complication of long-standing ulcerative colitis (UC). MicroRNAs (miRNA) are epigenetic regulators that have been involved in the development of UC-associated CRC. However, their role as potential mucosal biomarkers of neoplastic progression has not been adequately studied.

METHODS

In this study, we analyzed the expression of 96 preselected miRNAs in human formalin-fixed and paraffin-embedded tissue of 52 case biopsies (20 normal mucosa, 20 dysplasia, and 12 UC-associated CRCs) and 50 control biopsies (10 normal mucosa, 21 sporadic adenomas, and 19 sporadic CRCs) by using Custom TaqMan Array Cards. For validation of deregulated miRNAs, we performed individual quantitative real-time polymerase chain reaction in an independent cohort of 50 cases (13 normal mucosa, 25 dysplasia, and 12 UC-associated CRCs) and 46 controls (7 normal mucosa, 19 sporadic adenomas, and 20 sporadic CRCs).

RESULTS

Sixty-four miRNAs were found to be differentially deregulated in the UC-associated CRC sequence. Eight of these miRNAs were chosen for further validation. We confirmed miR-31, -106a, and -135b to be significantly deregulated between normal mucosa and dysplasia, as well as across the UC-associated CRC sequence (all P < 0.01). Notably, these miRNAs also confirmed to have a significant differential expression compared with sporadic CRC (all P < 0.05).

DISCUSSION

UC-associated and sporadic CRCs have distinct miRNA expression patterns, and some miRNAs indicate early neoplastic progression.

MicroRNA Expression Profiling Predicts Nodal Status and Disease Recurrence in Patients Treated with Curative Intent for Colorectal Cancer

Background: Approximately one-third of colorectal cancer (CRC) patients will suffer recurrence. MiRNAs are small non-coding RNAs that play important roles in gene expression. We aimed to correlate miRNA expression with aggressive clinicopathological characteristics and survival outcomes in CRC. Methods: Tumour samples were extracted from 74 CRC patients. MiRNAs were quantified using real-time reverse transcriptase polymerase chain reaction. Descriptive statistics and Cox regression analyses were performed to correlate miRNA targets with clinicopathological and outcome data. Results: Aberrant miR-21 and miR-135b expression correlate with increased nodal stage (p = 0.039, p = 0.022). Using univariable Cox regression analyses, reduced miR-135b (β-coefficient −1.126, hazard ratio 0.324, standard error (SE) 0.4698, p = 0.017) and increased miR-195 (β-coefficient 1.442, hazard ratio 4.229, SE 0.446, p = 0.001) predicted time to disease recurrence. Survival regression trees analysis illustrated a relative cut-off of ≤0.488 for miR-195 and a relative cut-off of >−0.218 for miR-135b; both were associated with improved disease recurrence (p < 0.001, p = 0.015). Using multivariable analysis with all targets as predictors, miR-195 (β-coefficient 3.187, SE 1.419, p = 0.025) was the sole significant independent predictor of recurrence. Conclusion: MiR-195 has strong value in predicting time to recurrence in CRC patients. Additionally, miR-21 and miR-135b predict the degree nodal burden. Future studies may include these findings to personalize therapeutic and surgical decision making.

Loss of microRNA-135b Enhances Bone Metastasis in Prostate Cancer and Predicts Aggressiveness in Human Prostate Samples

About 70% of advanced-stage prostate cancer (PCa) patients will experience bone metastasis, which severely affects patients' quality of life and progresses to lethal PCa in most cases. Hence, understanding the molecular heterogeneity of PCa cell populations and the signaling pathways associated with bone tropism is crucial. For this purpose, we generated an animal model with high penetrance to metastasize to bone using an intracardiac percutaneous injection of PC3 cells to identify PCa metastasis-promoting factors. Using genomic high-throughput analysis we identified a miRNA signature involved in bone metastasis that also presents potential as a biomarker of PCa progression in human samples. In particular, the downregulation of miR-135b favored the incidence of bone metastases by significantly increasing PCa cells' migratory capacity. Moreover, the PLAG1, JAKMIP2, PDGFA, and VTI1b target genes were identified as potential mediators of miR-135b's role in the dissemination to bone. In this study, we provide a genomic signature involved in PCa bone growth, contributing to a better understanding of the mechanisms responsible for this process. In the future, our results could ultimately translate into promising new therapeutic targets for the treatment of lethal PCa.

Colon cancer therapy by focusing on colon cancer stem cells and their tumor microenvironment

Despite many advances and optimization in colon cancer treatment, tumor recurrence and metastases make the development of new therapies necessary. Colon cancer stem cells (CCSCs) are considered as the main triggering factor of cancer progression, recurrence, and metastasis. CCSCs as a result of accumulated genetic and epigenetic alterations and also complex interconnection with the tumor microenvironment (TME) can evolve and convert to full malignant cells. Mounting evidence suggests that in cancer therapy both CCSCs and non-CCSCs in TME have to be regarded to break through the limitation of current therapies. In this regard, stem cell capabilities of some non-CCSCs may arise inside the TME condition. Therefore, a deep knowledge of regulatory mechanisms, heterogeneity, specific markers, and signaling pathways of CCSCs and their interconnection with TME components is needed to improve the treatment of colorectal cancer and the patient's life quality. In this review, we address current different targeted therapeutic options that target cell surface markers and signaling pathways of CCSCs and other components of TME. Current challenges and future perspectives of colon cancer personalized therapy are also provided here. Taken together, based on the deep understanding of biology of CCSCs and using three-dimensional culture technologies, it can be possible to reach successful colon cancer eradication and improvise combination targeted therapies against CCSCs and TME.

Relationship between Fusobacterium nucleatum, inflammatory mediators and microRNAs in colorectal carcinogenesis

AIM

To examine the effect of Fusobacterium nucleatum (F. nucleatum) on the microenvironment of colonic neoplasms and the expression of inflammatory mediators and microRNAs (miRNAs).

METHODS

Levels of F. nucleatum DNA, cytokine gene mRNA (TLR2, TLR4, NFKB1, TNF, IL1B, IL6 and IL8), and potentially interacting miRNAs (miR-21-3p, miR-22-3p, miR-28-5p, miR-34a-5p, miR-135b-5p) were measured by quantitative polymerase chain reaction (qPCR) TaqMan^® assays in DNA and/or RNA extracted from the disease and adjacent normal fresh tissues of 27 colorectal adenoma (CRA) and 43 colorectal cancer (CRC) patients. KRAS mutations were detected by direct sequencing and microsatellite instability (MSI) status by multiplex PCR. Cytoscape v3.1.1 was used to construct the postulated miRNA:mRNA interaction network.

RESULTS

Overabundance of F. nucleatum in neoplastic tissue compared to matched normal tissue was detected in CRA (51.8%) and more markedly in CRC (72.1%). We observed significantly greater expression of TLR4, IL1B, IL8, and miR-135b in CRA lesions and TLR2, IL1B, IL6, IL8, miR-34a and miR-135b in CRC tumours compared to their respective normal tissues. Only two transcripts for miR-22 and miR-28 were exclusively downregulated in CRC tumour samples. The mRNA expression of IL1B, IL6, IL8 and miR-22 was positively correlated with F. nucleatum quantification in CRC tumours. The mRNA expression of miR-135b and TNF was inversely correlated. The miRNA:mRNA interaction network suggested that the upregulation of miR-34a in CRC proceeds via a TLR2/TLR4-dependent response to F. nucleatum. Finally, KRAS mutations were more frequently observed in CRC samples infected with F. nucleatum and were associated with greater expression of miR-21 in CRA, while IL8 was upregulated in MSI-high CRC.

CONCLUSION

Our findings indicate that F. nucleatum is a risk factor for CRC by increasing the expression of inflammatory mediators through a possible miRNA-mediated activation of TLR2/TLR4.

TGF-β1 promoted chondrocyte proliferation by regulating Sp1 through MSC-exosomes derived miR-135b

OBJECTIVE

The aim of this study was to investigate the molecular mechanism of TGF-β1 in regulating chondrocyte proliferation through MSC-exosomes.

METHODS

An osteoarthritis (OA) rat model was established. Cartilage degradation was quantified by using OARSI score. TGF-β1 was used to stimulate MSCs. The expressions of miR-135b and Sp1 in MSCs, MSC-exosomes and C5.18 cells were detected. The cell viability of C5.18 cells was measured using MTT assay.

RESULTS

TGF-β1 stimulation enhanced miR-135b expression in MSC-exosomes, and MSC-exosomes derived miR-135b increased the cell viability of C5.18 cells. Moreover, miR-135b negatively regulated Sp1 expression. The cell viability of C5.18 cells in TGF-β1+miR-135b inhibitor+si-control group was reduced, while the cell viability in TGF-β1+miR-135b inhibitor+si-Sp1 group was enhanced. In rat experiments, OARSI score was decreased and the number of chondrocytes was increased in OA+TGF-β1+MSC-exosome group, while the score and the number had an opposite trend in OA+TGF-β1+MSC-miR135b inhibitor-exosome group.

CONCLUSION

TGF-β1 promoted chondrocyte proliferation by regulating Sp1 through MSC-exosomes derived miR-135b, then promoted cartilage repair.

MTSS1/Src family kinase dysregulation underlies multiple inherited ataxias

The genetically heterogeneous spinocerebellar ataxias (SCAs) are caused by Purkinje neuron dysfunction and degeneration, but their underlying pathological mechanisms remain elusive. The Src family of nonreceptor tyrosine kinases (SFK) are essential for nervous system homeostasis and are increasingly implicated in degenerative disease. Here we reveal that the SFK suppressor Missing-in-metastasis (MTSS1) is an ataxia locus that links multiple SCAs. MTSS1 loss results in increased SFK activity, reduced Purkinje neuron arborization, and low basal firing rates, followed by cell death. Surprisingly, mouse models for SCA1, SCA2, and SCA5 show elevated SFK activity, with SCA1 and SCA2 displaying dramatically reduced MTSS1 protein levels through reduced gene expression and protein translation, respectively. Treatment of each SCA model with a clinically approved Src inhibitor corrects Purkinje neuron basal firing and delays ataxia progression in MTSS1 mutants. Our results identify a common SCA therapeutic target and demonstrate a key role for MTSS1/SFK in Purkinje neuron survival and ataxia progression.

MicroRNAs in the prognosis and therapy of colorectal cancer: From bench to bedside

MicroRNAs (miRNAs) are small, single-stranded, noncoding RNAs that can post-transcriptionally regulate the expression of various oncogenes and tumor suppressor genes. Dysregulated expression of many miRNAs have been shown to mediate the signaling pathways critical in the multistep carcinogenesis of colorectal cancer (CRC). MiRNAs are stable and protected from RNase-mediated degradation, thereby enabling its detection in biological fluids and archival tissues for biomarker studies. This review focuses on the role and application of miRNAs in the prognosis and therapy of CRC. While stage II CRC is potentially curable by surgical resection, a significant percentage of stage II CRC patients do develop recurrence. MiRNA biomarkers may be used to stratify such high-risk population for adjuvant chemotherapy to provide better prognoses. Growing evidence also suggests that miRNAs are involved in the metastatic process of CRC. Certain of these miRNAs may thus be used as prognostic biomarkers to identify patients more likely to have micro-metastasis, who could be monitored more closely after surgery and/or given more aggressive adjuvant chemotherapy. Intrinsic and acquired resistance to chemotherapy severely hinders successful chemotherapy in CRC treatment. Predictive miRNA biomarkers for response to chemotherapy may identify patients who will benefit the most from a particular regimen and also spare the patients from unnecessary side effects. Selection of patients to receive the new targeted therapy is becoming possible with the use of predictive miRNA biomarkers. Lastly, forced expression of tumor suppressor miRNA or silencing of oncogenic miRNA in tumors by gene therapy can also be adopted to treat CRC alone or in combination with other chemotherapeutic drugs.

Tumor-derived extracellular vesicles in angiogenesis

Angiogenesis is crucial for tumor growth and metastasis. Recent studies revealed that tumor cells promote angiogenesis by secreting extracellular vesicles, which can be captured by endothelial cells. These tumor-derived extracellular vesicles carry microRNAs, long non-coding RNAs, and proteins, which activate pro-angiogenic signaling in endothelial cells. In this review, we will summarize the roles of tumor-derived extracellular vesicles in angiogenesis and the underlying molecular mechanisms.

Metastasis suppressor 1 (MTSS1) expression is associated with reduced in-vivo metastasis and enhanced patient survival in lung adenocarcinoma

Metastasis suppressor 1 (MTSS1) has been shown to be a metastasis suppressor in a number of cancers. However, its role in lung adenocarcinoma is largely unknown. To evaluate the significance of MTSS1 expression on lung adenocarcinoma metastatic properties, the gain or loss of MTSS1 in in vivo and in vitro experiments were employed. Using an in vivo orthotopic mouse xenograft model mimicking human disease progression, stable overexpression of MTSS1 in lung adenocarcinoma cells resulted in a significant decrease in metastatic burden. Stable overexpression of MTSS1 in NCI-H1299 decreased in vitro lung adenocarcinoma invasion and migration while knockdown of MTSS1 in A549 resulted in a significant increase in cell invasion and migration. Using The Cancer Genome Atlas dataset of over 500 patient lung adenocarcinoma specimens, we demonstrated a 20% increase in 5-year survival associated with preserved intratumoral MTSS expression. MTSS1 expression in lung adenocarcinoma is associated with decreased metastatic burden, as assessed by an in vivo orthotopic model, and correlates with a 20% survival advantage at 5 years following diagnosis. In vitro data suggests MTSS1 regulates lung adenocarcinoma through augmentation of cell invasion and migration.

miR-182 and miR-135b Mediate the Tumorigenesis and Invasiveness of Colorectal Cancer Cells via Targeting ST6GALNAC2 and PI3K/AKT Pathway

BACKGROUND

Metastasis is a leading cause of cancer-related death including colorectal cancer (CRC). MicroRNAs are known to regulate cancer pathways and to be expressed aberrantly in cancer. Aberrant sialylation is closely associated with malignant phenotype of tumor cells, including invasiveness and metastasis.

AIM

This study aimed to investigate the association of miR-182 and miR-135b with proliferation and invasion by targeting sialyltransferase ST6GALNAC2 in CRC cells and explore the potential molecular mechanism.

METHODS

We measured the levels of miR-182, miR-135b, and ST6GALNAC2 in a series of CRC cell lines and tissues using real-time PCR. Bioinformatics analysis and luciferase reporter assay were performed to test the direct binding of miR-182 and miR-135b to the target gene ST6GALNAC2. We also analyzed the possible role of miR-182/-135b on colony formation, wound healing, invasion, and tube formation.

RESULTS

The expression of miR-182 and miR-135b was higher in tumor tissues compared to adjacent noncancerous tissues of CRC patients, as well as up-regulated in SW620 cells than in SW480 cells with different metastatic potential. By applying bioinformatics analysis and luciferase reporter assay, we identified ST6GALNAC2 as the direct target of miR-182/-135b. Furthermore, miR-182/-135b inhibited significantly ST6GALNAC2 expression, and consistently, ST6GALNAC2 mediated migration, adhesion, invasion, proliferation, and tumor angiogenesis in CRC cell lines. Additionally, PI3K/AKT signaling pathway was regulated by miR-182/135b, which was partially blocked by altered level of ST6GALNAC2 in CRC.

CONCLUSIONS

The miR-182/-135b/ST6GALNAC2/PI3K/AKT axis may serve as a predictive biomarker and a potential therapeutic target in CRC treatment.

PTEN-Dependent Stabilization of MTSS1 Inhibits Metastatic Phenotype in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) presents at metastatic stage in over 50% of patients. With a survival rate of just 2.7% for patients presenting with distant disease, it is imperative to uncover novel mechanisms capable of suppressing metastasis in PDAC. Previously, we reported that the loss of metastasis suppressor protein 1 (MTSS1) in PDAC cells results in significant increase in cellular migration and invasion. Conversely, we also found that overexpressing MTSS1 in metastatic PDAC cell lines corresponds with not only decreased metastatic phenotype, but also greater overall survival. While it is known that MTSS1 is downregulated in late-stage PDAC, the mechanism behind that loss has not yet been elucidated. Here, we build off our previous findings to present a novel regulatory mechanism for the stabilization of MTSS1 via the tumor suppressor protein phosphatase and tensin homolog (PTEN). We show that PTEN loss in PDAC cells results in a decrease in MTSS1 expression and increased metastatic potential. Additionally, we demonstrate that PTEN forms a complex with MTSS1 in order to stabilize and protect it from proteasomal degradation. Finally, we show that the inflammatory tumor microenvironment, which makes up over 90% of PDAC tumor bulk, is capable of downregulating PTEN expression through secretion of miRNA-23b, potentially uncovering a novel extrinsic mechanism of MTSS1 regulation. Collectively, these data offer new insight into the role and regulation of MTSS1in suppressing tumor cell invasion and migration and help shed light as to what molecular mechanisms could be leading to early cell dissemination in PDAC.

Prognostic impact of a novel gene expression profile classifier for the discrimination between metastatic and non-metastatic primary colorectal cancer tumors

Despite significant advances have been achieved in the genetic characterization of sporadic colorectal cancer (sCRC), the precise genetic events leading to the development of distant metastasis remain poorly understood. Thus, accurate prediction of metastatic disease in newly-diagnosed sCRC patients remains a challenge. Here, we evaluated the specific genes and molecular pathways associated with the invasive potential of colorectal tumor cells, through the assessment of the gene expression profile (GEP) of coding and non-coding genes in metastatic (MTX) vs. non-metastatic (non-MTX) primary sCRC tumors followed for >5 years. Overall, MTX tumors showed up-regulation of genes associated with tumor progression and metastatic potential while non-MTX cases displayed GEP associated with higher cell proliferation, activation of DNA repair and anti-tumoral immune/inflammatory responses. Based on only 19 genes a specific GEP that classifies sCRC tumors into two MTX-like and non-MTX-like molecular subgroups was defined which shows an independent prognostic impact on patient overall survival, particularly when it is combined with the lymph node status at diagnosis. In summary, we show an association between the global GEP of primary sCRC cells and their metastatic potential and defined a GEP-based classifier that provides the basis for further prognostic stratification of sCRC patients who are at risk of distant metastases.

Peripheral lung adenocarcinomas harboring epithelial growth factor receptor mutations with microRNA-135b overexpression are more likely to invade visceral pleura

Lung adenocarcinoma, characterized by its early and aggressive local invasion and high metastatic potential, is the most frequently observed histological type of non-small-cell lung cancer (NSCLC). Visceral pleural invasion (VPI) caused by peripheral lung adenocarcinomas is closely associated with the poor prognosis of patients with NSCLC. The association between VPI and some clinicopathological characteristics has been observed in the past few decades. However, the molecular mechanism of VPI in lung adenocarcinomas is unknown. In the present, the expression level of microRNA (miR-)135b and epidermal growth factor receptor (EGFR) mutations using the reverse transcription-quantitative polymerase chain reaction and DNA sequencing, respectively. In addition, the present study aimed at exploring the association between the miR-135b level, EGFR mutations and VPI in peripheral lung adenocarcinoma. The results of the present study demonstrated that miR-135b was significantly upregulated in lung adenocarcinoma compared with adjacent normal tissue and positively associated EGFR mutations in peripheral lung adenocarcinoma. Furthermore, it was identified that lung adenocarcinomas with EGFR mutations and miR-135b overexpression were more likely to invade visceral pleura. Taken together, these findings indicate that miR-135b overexpression is positively associated with mutations to EGFR, which may promote the development of peripheral lung adenocarcinomas by the formation of VPI. This indicates that the two factors may serve as prognostic markers and molecular targets for the treatment of peripheral lung adenocarcinomas.

A novel SNP in promoter region of RP11-3N2.1 is associated with reduced risk of colorectal cancer

Single-nucleotide polymorphisms (SNPs) in the promoter region of long intergenic non-coding RNAs (lincRNAs) could play a regulatory role in its expression level and then get involved in colorectal cancer (CRC). Thus, we conducted a two-stage case-control study to investigate the associations of Tag SNPs within the promoter region of selected lincRNAs from microarray data with risk of CRC. A total of 320 cases and 319 controls were recruited in the test set to explore the associations between 16 SNPs with no deviations from Hardy-Weinberg equilibrium (HWE) and risk of CRC. Furthermore, 501 cases and 538 controls were included as the validation set to confirm the significant associations. RP11-3N2.1 rs13230517 polymorphism was found to be negatively associated with CRC in both test set (AA vs. GG, OR = 0.68, 95% CI = 0.48-0.96) and validation set (AA vs. GG, OR = 0.76, 95% CI = 0.59-0.98). Pooled analysis showed that individuals with GA/AA genotypes had a significantly decreased risk of CRC when compared with those carrying GG genotype (OR = 0.74, 95% CI = 0.60-0.90) in the combined set. The crossover analysis revealed that rs13230517 GA/AA carriers had a decreased risk of CRC than GG carriers among non-drinkers in both test and combined set. However, no gene-environment multiplicative interactions were found on risk of CRC. Our findings suggest that rs13230517 polymorphism might participate in the pathogenesis of CRC and have the potential to be a biomarker for predicting the risk of CRC.

Loss of MTSS1 results in increased metastatic potential in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) has a 5-year survival rate of 7%. This dismal prognosis is largely due to the inability to diagnose the disease before metastasis occurs. Tumor cell dissemination occurs early in PDAC. While it is known that inflammation facilitates this process, the underlying mechanisms responsible for this progression have not been fully characterized. Here, we functionally test the role of metastasis suppressor 1 (MTSS1) in PDAC. Despite evidence showing that MTSS1 could be important for regulating metastasis in many different cancers, its function in PDAC has not been studied. Here, we show that loss of MTSS1 leads to increased invasion and migration in PDAC cell lines. Moreover, PDAC cells treated with cancer-associated fibroblast-conditioned media also have increased metastatic potential, which is augmented by loss of MTSS1. Finally, overexpression of MTSS1 in PDAC cell lines leads to a loss of migratory potential in vitro and an increase in overall survival in vivo. Collectively, our data provide insight into an important role for MTSS1 in suppressing tumor cell invasion and migration driven by the tumor microenvironment and suggest that therapeutic strategies aimed at increasing MTSS1 levels may effectively slow the development of metastatic lesions, increasing survival of patients with PDAC.

Upregulation of microRNA-135b and microRNA-182 promotes chemoresistance of colorectal cancer by targeting ST6GALNAC2 via PI3K/AKT pathway

MicroRNAs (miRNAs) are increasingly involved in the development of drug resistance, including 5-fluorouracil (5-FU) resistance in colorectal cancer (CRC). Aberrant sialylation is correlated with human CRC. The study was to explore whether miR-135b and miR-182 modulated 5-FU chemoresistance of CRC by targeting ST6GALNAC2 via PI3K/AKT pathway. MiR-135b and miR-182 were found to be up-regulated in CRC tissues and 5-FU resistant CRC cell lines. Forced miR-135b and miR-182 expression also affected ST6GALNAC2 levels. Using reporter-gene assay, ST6GALNAC2 was identified as direct target of miR-135b and miR-182, while ST6GALNAC2 expression exhibited patterns opposite to that of miR-135b and miR-182 in CRC samples and cell lines. Interestingly, up-regulation of miR-135b or miR-182 increased drug resistance and proliferation, but decreased apoptosis in 5-FU resistant CRC cell lines. Suppression of these miRNAs implicated an inverse function, while altered expression of ST6GALNAC2 mediated CRC progression upon transfection with miR-135b/-182 mimic or inhibitor. Furthermore, miR-135b and miR-182 were clarified to regulate the activity of phosphoinositide-3 kinase (PI3K)/AKT pathway. Inhibition of the PI3K/AKT pathway enhanced the chemosensitivity to 5-FU in HCT-8/5-FU and LoVo/5-FU. Taken together, miR-135b and miR-182 may reverse the resistance to 5-FU in CRC cells by targeting ST6GALNAC2 via PI3K/AKT pathway, which render potential chemotherapy targets for the treatment of CRC.

MicroRNA-761 promotes the sensitivity of colorectal cancer cells to 5-Fluorouracil through targeting FOXM1

Resistance to chemotherapy is a big challenge for treatment of patients with colorectal cancer; however; the mechanism underlying chemoresistance in colorectal cancer cell has not been elucidated. MicroRNAs (miRNAs) are new players in the development of drug chemoresistance. In our study, we indicated that overexpression of miR-761 promoted the sensitivity of colorectal cancer cells to 5-Fluorouracil (5-FU). miR-761 expression was downregulated in colorectal cancer cell lines and tissues. miR-761 expression was lower in patients with low grade than in patients with high grade. In additon, we showed that elevated expression of miR-761 suppressed colorectal cancer cell proliferation, cell cycle, colony formation and cell invasion. We identified that FOXM1 was a direct target gene of miR-761 in colorectal cancer cell. FOXM1 expression was upregulated in colorectal cancer tissues compare to the adjacent non-tumor tissues. MiR-761 expression was negatively associated with the expression of FOXM1 in colorectal cancer tissues. Elevated expression of FOXM1 suppressed the sensitivity of miR-761-overexpressing HT29 cells to 5-FU. We also indicated that FOXM1 overexpression promoted cell proliferation, cycle and invasion of miR-761-overexpressing HT29 cells. These data suggested that miR-761 played a tumor suppressor miRNA in colorectal cancer progression and reduced miR-761 expression might be a major mechanism for 5-FU resistance in colorectal cancer cell.

MicroRNA-186-5p overexpression modulates colon cancer growth by repressing the expression of the FAM134B tumour inhibitor

OBJECTIVES

The role and underlying mechanism of miR-186-5p in colorectal cancer remain unknown. The present study aims to examine the various cellular effects of miR-186-5p in the carcinogenesis of colorectal cancer. Also, the interacting targets and association of clinicopathological factors with miR-186-5p expression in patients with colorectal cancer were analysed.

METHODS

The miR-186-5p expression levels in colorectal cancer tissues (n=126) and colon cancer cell lines (n=3) were analysed by real-time PCR. Matched non-neoplastic colorectal tissues and a non-neoplastic colonic epithelial cell line were used as controls. Various in vitro assays such as cell proliferation, wound healing and colony formation assays were performed to examine the miR-186-5p specific cellular effects. Western blots and immunohistochemistry analysis were performed to examine the modulation of FAM134B, PARP9 and KLF7 proteins expression.

RESULTS

Significant high expression of miR-186-5p was noted in cancer tissues (p< 0.001) and cell lines (p<0.05) when compared to control tissues and cells. The majority of the patients with colorectal cancer (88/126) had shown overexpression of miR-186-5p. This miR-186-5p overexpression was predominantly noted with in cancer with distant metastasis (p=0.001), lymphovascular permeation (p=0.037), microsatellite instability (MSI) stable (p=0.015), in distal colorectum (p=0.043) and with associated adenomas (p=0.047). Overexpression of miR-186-5p resulted in increased cell proliferation, colony formation, wound healing capacities and induced alteration of cell cycle kinetics in colon cancer cells. On the other hand, inhibition of endogenous miR-186-5p reduced the cancer growth properties. miR-186-5p overexpression reduced FAM134B expression significantly in the cancer cells (p<0.01). Also, FAM134B and miR-186-5p expressions are inversely correlated in colorectal cancer tissues and cells.

CONCLUSION

The miR-186-5p expression promotes colorectal cancer pathogenesis by regulating tumour suppressor FAM134B. Reduced cancer cells growth followed by inhibition of miR-186-5p highlights the potential of miR-186-5p inhibitor as a novel strategy for targeting colorectal cancer initiation and progression.

Exploration of small RNA-seq data for small non-coding RNAs in Human Colorectal Cancer

Background: Improved healthcare and recent breakthroughs in technology have substantially reduced cancer mortality rates worldwide. Recent advancements in next-generation sequencing (NGS) have allowed genomic analysis of the human transcriptome. Now, using NGS we can further look into small non-coding regions of RNAs (sncRNAs) such as microRNAs (miRNAs), Piwi-interacting-RNAs (piRNAs), long non-coding RNAs (lncRNAs), and small nuclear/nucleolar RNAs (sn/snoRNAs) among others. Recent studies looking at sncRNAs indicate their role in important biological processes such as cancer progression and predict their role as biomarkers for disease diagnosis, prognosis, and therapy. Results: In the present study, we data mined publically available small RNA sequencing data from colorectal tissue samples of eight matched patients (benign, tumor, and metastasis) and remapped the data for various small RNA annotations. We identified aberrant expression of 13 miRNAs in tumor and metastasis specimens [tumor vs benign group (19 miRNAs) and metastasis vs benign group (38 miRNAs)] of which five were upregulated, and eight were downregulated, during disease progression. Pathway analysis of aberrantly expressed miRNAs showed that the majority of miRNAs involved in colon cancer were also involved in other cancers. Analysis of piRNAs revealed six to be over-expressed in the tumor vs benign cohort and 24 in the metastasis vs benign group. Only two piRNAs were shared between the two cohorts. Examining other types of small RNAs [sn/snoRNAs, mt_rRNA, miscRNA, nonsense mediated decay (NMD), and rRNAs] identified 15 sncRNAs in the tumor vs benign group and 104 in the metastasis vs benign group, with only four others being commonly expressed. Conclusion: In summary, our comprehensive analysis on publicly available small RNA-seq data identified multiple differentially expressed sncRNAs during colorectal cancer progression at different stages compared to normal colon tissue. We speculate that deciphering and validating the roles of sncRNAs may prove useful in colorectal cancer prognosis, diagnosis, and therapy.

Role of Akt2 in regulation of metastasis suppressor 1 expression and colorectal cancer metastasis

Survival signaling is critical for the metastatic program of cancer cells. The current study investigated the role of Akt survival proteins in colorectal cancer (CRC) metastasis and explored potential mechanisms of Akt-mediated metastasis regulation. Using an orthotopic implantation model in mice, which uniquely recapitulates the entire multistep process of CRC metastasis, combined with an inducible system of short hairpin RNA-mediated Akt isoform knockdown in human CRC cells, our studies confirm a role of Akt2 in CRC cell dissemination to distant organs in vivo. Akt2 deficiency profoundly inhibited the development of liver lesions in mice, whereas Akt1 had no effect under the experimental conditions used in the study. Array analysis of human metastatic genes identified the scaffolding protein metastasis suppressor 1 (MTSS1) as a novel Akt2-regulated gene. Inducible loss of Akt2 in CRC cells robustly upregulated MTSS1 at the messenger RNA and protein level, and the accumulated protein was functionally active as shown by its ability to engage an MTSS1-Src-cortactin inhibitory axis. MTSS1 expression led to a marked reduction in levels of functional cortacin (pcortactin Y421), an actin nucleation-promoting factor that has a crucial role in cancer cell invasion and metastasis. MTSS1 was also shown to mediate suppressive effects of Akt2 deficiency on CRC cell viability, survival, migration and actin polymerization in vitro. The relevance of these findings to human CRC is supported by analysis of The Cancer Genome Atlas (TCGA) and NCBI GEO data sets, which demonstrated inverse changes in expression of Akt2 and MTSS1 during CRC progression. Taken together, the data identify MTSS1 as a new Akt2-regulated gene, and point to suppression of MTSS1 as a key step in the metastasis-promoting effects of Akt2 in CRC cells.

miR-135b, a key regulator of malignancy, is linked to poor prognosis in human myxoid liposarcoma

Myxoid/round cell (RC) liposarcomas (MLS) were originally classified into two distinct populations based on histological differences; a myxoid component and a RC component. It is notable that, depending on an increase of the RC component, the prognosis significantly differs. Hence, the RC component is associated with metastasis and poor prognosis. However, the molecular mechanisms that contribute to the malignancy of the RC component still remain largely unknown. Here, we report microRNA-135b (miR-135b), a key regulator of the malignancy, highly expressed in the RC component and promoting MLS cell invasion in vitro and metastasis in vivo through the direct suppression of thrombospondin 2 (THBS2). Decreased THBS2 expression by miR-135b increases the total amount of matrix metalloproteinase 2 (MMP2) and influences cellular density and an extracellular matrix structure, thereby resulting in morphological change in tumor. The expression levels of miR-135b and THBS2 significantly correlated with a poor prognosis in MLS patients. Overall, our study reveals that the miR-135b/THBS2/MMP2 axis is tightly related to MLS pathophysiology and has an important clinical implication. This work provides noteworthy evidence for overcoming metastasis and improving patient outcomes, and sheds light on miR-135b and THBS2 as novel molecular targets for diagnosis and therapy in MLS.

MicroRNAs in colorectal carcinoma--from pathogenesis to therapy

Background

Acting as inflammatory mediators, tumor oncogenes or suppressors, microRNAs are involved in cell survival, death, epithelial–mesenchymal transition and metastasis, etc. Investigating the communication between microRNAs and tumorigenesis is critical to our understanding of the pathogenesis of multiple disease states.

Main body

Currently, colorectal carcinoma (CRC), one of the most common malignancies worldwide, has a poor prognosis due to lack of an effective therapeutic option. Increasing evidence has identified altered profiles and regulatory potential of microRNAs in conditions related to environmentally-caused colorectal inflammation and colitis-associated cancer. Many studies have shed light on a more thorough understanding of the function and distribution of microRNAs in CRC initiation and emergence. However, the molecular mechanisms by which microRNAs modulate cellular processes still need to be further elucidated and may offer a foundation for evaluating microRNA-based therapeutic potential for CRC in both animal models and clinical trials.

Conclusion

In this review, the roles and mechanisms of microRNAs involved in CRC from pathogenesis to therapy are summarized and discussed, which may provide more useful hints for CRC prevention and therapy.

miR-135b, upregulated in breast cancer, promotes cell growth and disrupts the cell cycle by regulating LATS2

Dysregulation of microRNAs (miRNAs) plays a critical role in cancer progression. They can act as either oncogenes or tumor suppressor genes in human cancer. The purpose of this study was to investigate the crucial role of miR-135b in breast cancer and to validate whether miR-135b could regulate proliferation of breast cancer cells by effecting specific targets in the Hippo pathway. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was carried out to quantify the expression levels of miR-135b in both breast cancer tissues and cell lines. To characterize the function of miR-135b, MTT assays, colony formation assays, cell migration assays, cell invasion assays, and cell cycle assays were used. Luciferase reporter assays were performed to validate the regulation of a putative target of miR-135b, in corroboration with western blot assays. Finally, we verified the changes of cellular function after transfection of LATS2-siRNA. Our experiments indicate that expression of miR-135b was commonly upregulated in breast cancer specimens and breast cancer cells when compared with that in adjacent normal tissues and non-malignant breast epithelial cells. Enforced expression of miR-135b can regulate cellular proliferation, migration and invasion as well as disrupt the cell cycle of breast cancer cells. Luciferase assays revealed that miR-135b directly bound to the 3'-untranslated region (3'-UTR) of LATS2 (large tumor suppressor kinase 2), a critical gene in the Hippo pathway. Western blot analysis verified that miR-135b regulated the expression of LATS2 at protein levels. Further study demonstrated that the downstream gene of LATS2 in the Hippo pathway, such as cyclin-dependent kinase 2 (CDK2) and Phospho-Yes-associated protein (p-YAP), can also be regulated by miR-135b and LATS2 axis. Knockdown of endogenous LATS2 can mimic the result of miR-135b up-regulation in breast cancer. Taken together, our findings reveal that the miR-135b and LATS2 axis may be a potential therapeutic target for breast cancer in the future.

Clinical significance of expression of miR-135b, LZTS1 and β-catenin in pancreatic cancer

AIM: To detect the expression of miR-135b, LZTS1 and β-catenin in pancreatic cancer in an attempt to explore their clinical significance.

METHODS: Locked nucleic acid in situ hybridization (ISH) and immunohisto-chemistry were used to detect the expression of miR-135b, LZTS1 and β-catenin proteins in 70 pancreatic cancer tissues and adjacent normal tissues, respectively.

RESULTS: The positive rate of miR-135b in pancreatic cancer was higher than that in adjacent tissues (71.4% vs 42.9%, P = 0.001). The positive rates of LZTS1 and β-catenin proteins in pancreatic cancer were significantly lower than those in adjacent tissues (34.3% vs 68.6%, 34.3% vs 74.3%, P < 0.05). Expression of miR-135b had a negative correlation with that of LZTS1 in pancreatic cancer (r = -0.61, P < 0.05), but miR-135b expression had no significant correlation with β-catenin (r = 0.06, P > 0.05). LZTS1 expression had a positive correlation with that of β-catenin (r = 0.37, P < 0.05). Expression of miR-135b, LZTS1 and β-catenin was closely related with lymph node metastasis and clinical stage (P < 0.05), but had no correlation with patient age, sex, tumor site or histological grade (P > 0.05).

CONCLUSION: miR-135b is highly expressed in pancreatic cancer, while the expression of LZTS1 and β-catenin is decreased. Up-regulated expression of miR-135b may participate in the development of pancreatic cancer by down-regulating the expression of LZTS1 protein.

The potential diagnostic power of extracellular vesicle analysis for multiple myeloma

Multiple myeloma (MM) is a hematologic malignancy of plasma cells (PCs). In the United States, MM accounts for approximately 1% of all diagnoses and 2% of all cancer-related deaths. Although MM is a treatable disease, most patients eventually relapse, and despite the development of numerous treatment options it is still considered incurable. Mechanisms of communication between MM-PCs and bone marrow microenvironment, including cell-cell contacts and release of pro-survival factors, promote cancer cell survival and drug resistance. Recently, the importance of extracellular vesicles (EVs) as mechanisms of communication between MM cells and other cells in the microenvironment has been reported. In this review, the authors provide the update on the biology and clinical aspects of EVs in MM.

Expression and Significances of MTSS1 in Pancreatic Cancer

Thus far, expression of metastasis suppressor 1 (MTSS1), its clinicopathologic and prognostic significances in pancreatic cancer (PC) remain unknown. Expression of MTSS1 was detected by Western blotting in PC cell lines, and by tissue microarray-based immunohistochemical staining in paired tumor and non-tumor samples from 242 patients with PC. Furthermore, the correlations between MTSS1 expression and clinicopathologic variables as well as overall survival were evaluated. In PC cell lines, MTSS1 was differentially expressed. In addition, MTSS1 expression was significantly lower in tumor than in non-tumor tissues (P < 0.001 in both McNemar and Mann-Whitney U tests). High tumoral expression of MTSS1 was closely associated with absence of lymph node metastasis (P = 0.023). Univariate analysis found that high MTSS1 expression in tumor tissues was a strong predictor of favorable overall survival in the whole cohort (P < 0.001). Besides, its impacts on prognosis were also observed in nine out of fourteen subgroups. Finally, MTSS1 expression was identified as an independent prognostic marker in the whole cohort (P = 0.031) as well as in six subgroups (P < 0.05), as shown by multivariate Cox regression test. Down-regulation of MTSS1 expression is evident in PC, and is associated with lymph node metastasis and poor prognosis.

miR-135b- and miR-146b-dependent silencing of calcium-sensing receptor expression in colorectal tumors

Studies have shown that the calcium-sensing receptor (CaSR) mediates the antitumorigenic effects of calcium against colorectal cancer (CRC). Expression of the CaSR in colorectal tumors is often reduced. We have reported previously that silencing of CaSR in CRC is caused in part by methylation of CaSR promoter 2 and loss of histone acetylation. We investigated the impact of aberrant microRNA expression on loss of CaSR expression. A microarray study in two Caco-2 subclones (Caco2/AQ and Caco2/15) that have similar genetic background, but different CaSR expression levels (Caco2/AQ expressing more CaSR than Caco2/15), identified 22 differentially expressed microRNAs that potentially target the CaSR. We validated these results by performing gain- and loss-of-function studies with the top candidates: miR-9, miR-27a, miR-135b, and miR-146b. Modulation of miR-135b or miR-146b expression by mimicking or inhibiting their expression regulated CaSR protein levels in two different colon cancer cell lines: Caco2/AQ (moderate endogenous CaSR expression) and HT29 (low endogenous CaSR levels). Inhibition of miR-135b and miR-146b expression led to high CaSR levels and significantly reduced proliferation. In samples of colorectal tumors we observed overexpression of miR-135b and miR-146b, and this correlated inversely with CaSR expression (miR-135b: r = -0.684, p < 0.001 and miR-146b: r = -0.448, p < 0.001), supporting our in vitro findings. We demonstrate that miR-135b and miR-146b target the CaSR and reduce its expression in colorectal tumors, reducing the antiproliferative and prodifferentiating actions of calcium. This provides a new approach for finding means to prevent CaSR loss, developing better treatment strategies for CRC.

miR-135b Promotes Cancer Progression by Targeting Transforming Growth Factor Beta Receptor II (TGFBR2) in Colorectal Cancer

The transforming growth factor beta (TGF-β) signaling pathway is a tumor-suppressor pathway that is commonly inactivated in colorectal cancer (CRC). The inactivation of TGFBR2 is the most common genetic event affecting the TGF-β signaling pathway. However, the mechanism by which cancer cells downregulate TGFBR2 is unclear. In this study, we found that the TGFBR2 protein levels were consistently upregulated in CRC tissues, whereas its mRNA levels varied in these tissues, suggesting that a post-transcriptional mechanism is involved in the regulation of TGFBR2. Because microRNAs (miRNAs) are powerful post-transcriptional regulators of gene expression, we performed bioinformatic analyses to search for miRNAs that potentially target TGFBR2. We identified the specific targeting site of miR-135b in the 3'-untranslated region (3'-UTR) of TGFBR2. We further identified an inverse correlation between the levels of miR-135b and TGFBR2 protein, but not mRNA, in CRC tissue samples. By overexpressing or silencing miR-135b in CRC cells, we experimentally validated that miR-135b directly binds to the 3'-UTR of the TGFBR2 transcript and regulates TGFBR2 expression. Furthermore, the biological consequences of the targeting of TGFBR2 by miR-135b were examined using in vitro cell proliferation and apoptosis assays. We demonstrated that miR-135b exerted a tumor-promoting effect by inducing the proliferation and inhibiting the apoptosis of CRC cells via the negative regulation of TGFBR2 expression. Taken together, our findings provide the first evidence supporting the role of miR-135b as an oncogene in CRC via the inhibition of TGFBR2 translation.

Identification of the Adapter Molecule MTSS1 as a Potential Oncogene-Specific Tumor Suppressor in Acute Myeloid Leukemia

The adapter protein metastasis suppressor 1 (MTSS1) is implicated as a tumor suppressor or tumor promoter, depending on the type of solid cancer. Here, we identified Mtss1 expression to be increased in AML subsets with favorable outcome, while suppressed in high risk AML patients. High expression of MTSS1 predicted better clinical outcome of patients with normal-karyotype AML. Mechanistically, MTSS1 expression was negatively regulated by FLT3-ITD signaling but enhanced by the AML1-ETO fusion protein. DNMT3B, a negative regulator of MTSS1, showed strong binding to the MTSS1 promoter in PML-RARA positive but not AML1-ETO positive cells, suggesting that AML1-ETO leads to derepression of MTSS1. Pharmacological treatment of AML cell lines carrying the FLT3-ITD mutation with the specific FLT3 inhibitor PKC-412 caused upregulation of MTSS1. Moreover, treatment of acute promyelocytic cells (APL) with all-trans retinoic acid (ATRA) increased MTSS1 mRNA levels. Taken together, our findings suggest that MTSS1 might have a context-dependent function and could act as a tumor suppressor, which is pharmacologically targetable in AML patients.

MicroRNA-135b Regulates Leucine Zipper Tumor Suppressor 1 in Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin malignancy and it presents a therapeutic challenge in organ transplant recipient patients. Despite the need, there are only a few targeted drug treatment options. Recent studies have revealed a pivotal role played by microRNAs (miRNAs) in multiple cancers, but only a few studies tested their function in cSCC. Here, we analyzed differential expression of 88 cancer related miRNAs in 43 study participants with cSCC; 32 immunocompetent, 11 OTR patients, and 15 non-lesional skin samples by microarray analysis. Of the examined miRNAs, miR-135b was the most upregulated (13.3-fold, 21.5-fold; p=0.0001) in both patient groups. Similarly, the miR-135b expression was also upregulated in three cSCC cell lines when evaluated by quantitative real-time PCR. In functional studies, inhibition of miR-135b by specific anti-miR oligonucleotides resulted in upregulation of its target gene LZTS1 mRNA and protein levels and led to decreased cell motility and invasion of both primary and metastatic cSCC cell lines. In contrast, miR-135b overexpression by synthetic miR-135b mimic induced further down-regulation of LZTS1 mRNA in vitro and increased cancer cell motility and invasiveness. Immunohistochemical evaluation of 67 cSCC tumor tissues demonstrated that miR-135b expression inversely correlated with LZTS1 staining intensity and the tumor grade. These results indicate that miR-135b functions as an oncogene in cSCC and provide new understanding into its pathological role in cSCC progression and invasiveness.

MicroRNA‑135b regulates the stability of PTEN and promotes glycolysis by targeting USP13 in human colorectal cancers

Dysregulation of microRNAs has been reported to be involved in the progression of human colorectal cancers (CRCs). Loss of the adenomatous polyposis coli (APC) gene is a common initiating event in CRCs. PTEN inactivation by mutation or allelic loss also occurs in CRCs. miR‑135b was reported to be upregulated in CRCs and its overexpression was due to APC/β‑catenin and PTEN/PI3K pathway deregulation. APC was proven to be a target of miR‑135b and forms a feedback loop with miR‑135b. In the present study, we found that ubiquitin‑specific peptidase 13 (USP13) was a target of miR‑135b. miR‑135b downregulated the expression of USP13, and reduced the stability of PTEN. miR‑135b promoted cell proliferation and glycolysis that could be reversed by the overexpression of USP13 or PTEN. Moreover, knockdown of USP13 upregulated the levels of endogenous miR‑135b, but not those in CRC cells with PTEN mutation. The results showed positive feedback loops between miR‑135b and PTEN inactivation in CRCs.

MiR-135b promotes proliferation and invasion of osteosarcoma cells via targeting FOXO1

Recent data strongly suggest the important role of miRNAs in various cancer-related processes. Osteosarcoma (OS) is the most common primary cancer of the bone and usually leads to deaths due to its rapid proliferation and metastasis. Here, we demonstrated that compared with noncancerous bone tissues, miR-135b expression is frequently upregulated in OS specimens, inversely correlated with potential target-FOXO1 expression pattern. Bioinformatics analysis combined with experimental confirmation revealed FOXO1 is a direct target of miR-135b in OS. Functionally, miR-135b inhibitor significantly inhibited OS cells proliferation and invasion. Forced expression of FOXO1 showed the opposite effect, and FOXO1 knockdown abolished the effect of miR-135b inhibitor. Taken together, our data provide compelling evidence that miR-135b functions as an onco-miRNA in OS to promote OS cells proliferation and invasion, and its oncogenic effects are mediated chiefly through targeting FOXO1.

Exosomal miR-135b shed from hypoxic multiple myeloma cells enhances angiogenesis by targeting factor-inhibiting HIF-1

Exosomes are small endosome-derived vesicles containing a wide range of functional proteins, mRNA, and miRNA. Exosomal miRNA from cancer cells helps modulate the microenvironment. In multiple myeloma (MM), the massive proliferation of malignant plasma cells causes hypoxia. To date, the majority of in vitro hypoxia studies of cancer cells have used acute hypoxic exposure (3-24 hours). Thus, we attempted to clarify the role of MM-derived exosomes in hypoxic bone marrow by using MM cells grown continuously in vitro under chronic hypoxia (hypoxia-resistant MM [HR-MM] cells). The HR-MM cells produced more exosomes than the parental cells under normoxia or acute hypoxia conditions, and miR-135b was significantly upregulated in exosomes from HR-MM cells. Exosomal miR-135b directly suppressed its target factor-inhibiting hypoxia-inducible factor 1 (FIH-1) in endothelial cells. Finally, exosomal miR-135b from HR-MM cells enhanced endothelial tube formation under hypoxia via the HIF-FIH signaling pathway. This in vitro HR myeloma cell model will be useful for investigating MM cell-endothelial cell interactions under hypoxic conditions, which may mimic the in vivo bone marrow microenvironment. Although tumor angiogenesis is regulated by various factors, exosomal miR-135b may be a target for controlling MM angiogenesis.