Dysregulation of miR-126/Crk protein axis predicts poor prognosis in gastric cancer patients

Role of Some microRNA/ADAM Proteins Axes in Gastrointestinal Cancers as a Novel Biomarkers and Potential Therapeutic Targets—A Review

Gastrointestinal (GI) cancers are some of the most common cancers in the world and their number is increasing. Their etiology and pathogenesis are still unclear. ADAM proteins are a family of transmembrane and secreted metalloproteinases that play a role in cancerogenesis, metastasis and neoangiogenesis. MicroRNAs are small single-stranded non-coding RNAs that take part in the post-transcriptional regulation of gene expression. Some ADAM proteins can be targets for microRNAs. In this review, we analyze the impact of microRNA/ADAM protein axes in GI cancers.

Platelet-Derived miR-126-3p Directly Targets AKT2 and Exerts Anti-Tumor Effects in Breast Cancer Cells: Further Insights in Platelet-Cancer Interplay

Among the surrounding cells influencing tumor biology, platelets are recognized as novel players as they release microvesicles (MVs) that, once delivered to cancer cells, modulate signaling pathways related to cell growth and dissemination. We have previously shown that physiological delivery of platelet MVs enriched in miR-126 exerted anti-tumor effects in different breast cancer (BC) cell lines. Here, we seek further insight by identifying AKT2 kinase as a novel miR-126-3p direct target, as assessed by bioinformatic analysis and validated by luciferase assay. Both ectopic expression and platelet MV-mediated delivery of miR-126-3p downregulated AKT2 expression, thus suppressing proliferating and invading properties, in either triple negative (BT549 cells) or less aggressive Luminal A (MCF-7 cells) BC subtypes. Accordingly, as shown by bioinformatic analysis, both high miR-126 and low AKT2 levels were associated with favorable long-term prognosis in BC patients. Our results, together with the literature data, indicate that miR-126-3p exerts suppressor activity by specifically targeting components of the PIK3/AKT signaling cascade. Therefore, management of platelet-derived MV production and selective delivery of miR-126-3p to tumor cells may represent a useful tool in multimodal therapeutic approaches in BC patients.

Crk and CrkL as Therapeutic Targets for Cancer Treatment

Crk and CrkL are cellular counterparts of the viral oncoprotein v-Crk. Crk and CrkL are overexpressed in many types of human cancer, correlating with poor prognosis. Furthermore, gene knockdown and knockout of Crk and CrkL in tumor cell lines suppress tumor cell functions, including cell proliferation, transformation, migration, invasion, epithelial-mesenchymal transition, resistance to chemotherapy drugs, and in vivo tumor growth and metastasis. Conversely, overexpression of tumor cells with Crk or CrkL enhances tumor cell functions. Therefore, Crk and CrkL have been proposed as therapeutic targets for cancer treatment. However, it is unclear whether Crk and CrkL make distinct or overlapping contributions to tumor cell functions in various cancer types because Crk or CrkL have been examined independently in most studies. Two recent studies using colorectal cancer and glioblastoma cells clearly demonstrated that Crk and CrkL need to be ablated individually and combined to understand distinct and overlapping roles of the two proteins in cancer. A comprehensive understanding of individual and overlapping roles of Crk and CrkL in tumor cell functions is necessary to develop effective therapeutic strategies. This review systematically discusses crucial functions of Crk and CrkL in tumor cell functions and provides new perspectives on targeting Crk and CrkL in cancer therapy.

Quantitative assessment of glioblastoma phenotypes in vitro establishes cell migration as a robust readout of Crk and CrkL activity

The expression levels of CT10 regulator of kinase (Crk) and Crk-like (CrkL) are elevated in many human cancers, including glioblastoma (GBM), and are believed to contribute to poor prognosis. Although Crk and CrkL have been proposed as therapeutic targets in these tumors, the lack of a reliable, quantitative assay to measure Crk and CrkL activity has hindered development of inhibitors. Here, we knocked down Crk, CrkL, or both using siRNAs in a human GBM cell line, U-118MG, to determine the respective, quantitative contributions of Crk and CrkL to cellular phenotypes. The combined use of specific and potent Crk and CrkL siRNAs induced effective knockdown of CrkII, CrkI, and CrkL. Whereas Crk knockdown did not affect cell morphology, proliferation, adhesion, or invasion, CrkL knockdown caused shrinkage of cells and inhibition of cell proliferation, adhesion, and invasion. Crk/CrkL double knockdown resulted in more pronounced morphological alterations and more robust inhibition of proliferation, adhesion, and invasion. Furthermore, Crk/CrkL double knockdown completely blocked cell migration, and this effect was rescued by transient overexpression of CrkL but not of Crk. Quantification of protein levels indicated that CrkL is expressed more abundantly than CrkII and CrkI in U-118MG cells. These results demonstrate both the predominant role of CrkL and the essential overlapping functions of Crk and CrkL in U-118MG cells. Furthermore, our study indicates that migration of U-118MG cells depends entirely on Crk and CrkL. Thus, impedance-based, real-time measurement of tumor cell migration represents a robust assay for monitoring Crk and CrkL activities.

MicroRNA-126-5p suppresses cell proliferation, invasion and migration by targeting EGFR in liver cancer

BACKGROUND

The expression status and potential mechanistic involvement of microRNA (miR)-126-5p in hepatocellular carcinoma (HCC) are still elusive currently. Here we set out to address this issue both in cell lines and in patients' tissues.

METHODS

The relative expression levels of endogenous miR-126-5p and epidermal growth factor receptor (EGFR) were quantified by real-time polymerase chain reaction. Cell viability and proliferation were measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and clonogenic assays, respectively. Cell invasive and migrative capacities were determined by transwell and wound healing assays, respectively. The regulatory action of miR-126-5p on EGFR was interrogated by luciferase reporter assay. Translational level of EGFR was analyzed by Western blotting.

RESULTS

MiR-126-5p was significantly down-regulated in both HCC patients' tissues and cell lines. Forced expression of miR-126-5p greatly compromised cell viability, proliferation, invasion and migration, while miR-126-5p-specific inhibitor promoted these oncogenic phenotypes. MiR-126-5p mimics inhibited endogenous expression of EGFR and suppressed EGFR 3'-untranslated region-fused luciferase activity. Co-expression of EGFR in miR-126-5p-proficient cells completely restored cell migrative and invasive capacities, while co-transfection with EGFR siRNA significantly inhibited miR-126-5p inhibitor-induced cell invasion and migration.

CONCLUSION

MiR-126-5p was aberrantly decreased in HCC and subsequently relieved the suppression on EGFR expression, which consequently contributed to the tumor biology of HCC.

MicroRNA (miR) dysregulation during Helicobacter pylori-induced gastric inflammation and cancer development: critical importance of miR-155

Dysregulation of noncoding microRNA molecules has been associated with immune cell activation in the context of Helicobacter pylori induced gastric inflammation as well as carcinogenesis, but also with downregulation of mismatch repair genes, and may interfere with immune checkpoint proteins that lead to the overexpression of antigens on gastric tumor cells. Numerous miR-molecules have been described as important tools and markers in gastric inflammation and cancer development -including miR-21, miR-143, miR-145, miR-201, and miR-335- all of which are downregulated in gastric tumors, and involved in cell cycle growth or tumor invasion. Among the many microRNAs involved in gastric inflammation, adenocarcinoma development and immune checkpoint regulation, miR-155 is notable in that its upregulation is considered a key marker of chronic gastric inflammation that predisposes a patient to gastric carcinogenesis. Among various other miRs, miR-155 is highly expressed in activated B and T cells and in monocytes/macrophages present in chronic gastric inflammation. Notably, miR-155 was shown to downregulate the expression of certain MMR genes, such as MLH1, MSH2, and MSH6. In tumor-infiltrating miR-155-deficient CD8⁺ T cells, antibodies against immune checkpoint proteins restored the expression of several derepressed miR-155 targets, suggesting that miR-155 may regulate overlapping pathways to promote antitumor immunity. It may thus be of high clinical impact that gastric pathologies mediated by miR-155 result from its overexpression. This suggests that it may be possible to therapeutically attenuate miR-155 levels for gastric cancer treatment and/or to prevent the progression of chronic gastric inflammation into cancer.

microRNA-126 Is a Tumor Suppressor of Granulosa Cell Tumor Mediated by Its Host Gene EGFL7

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression at a post-transcriptional level. We examined the role of miR-126 in granulosa cell tumor (GCT) of the ovaries. In tissues from malignant GCT patients miR-126 expression was repressed. We showed that miR-126 could inhibit proliferation, migration, hormone production and promote apoptosis of cancerous granulosa cells (GCs) in vitro. The role of miR-126 as “tumor suppressor” was confirmed by using a tumor formation model in vivo. By RNA-seq, immunohistochemical staining (IHC), Western blot and luciferase reporter assay, we identified and confirmed EGFL7 as a direct functional target of miR-126 in cancer GCs. Furthermore, we found that the AKT signaling pathway was associated with miR-126 and EGFL7 in cancer GCs. Taken together, our results demonstrate a function of miR-126 in the suppression of GCT development via the regulation of EGFL7.

Low Expression of MicroRNA335-5p Is Associated with Malignant Behavior of Gallbladder Cancer: A Clinicopathological Study

Background: MicroRNAs (miRNAs) are non-coding RNAs that regulate multiple cellular processes during cancer progression, identified to be involved in tumorgenesis of several cancers including cancers of digestive system. However its role in gallbladder inflammatory disease (GID) and gallbladder cancer (GBC) has not been well documented. The present study was aimed to investigate the clinical significance of hsa-miRNA-335-5p (miR-335) in GBC and GID. Subjects and Methods: This prospective case control study, conducted from July 1, 2014 to December 1, 2017 in Era’s Lucknow Medical College & Hospital, India, evaluated miR-335 expression by real-time polymerase chain reaction. Hundred tissue samples GID (control; n=50) and GBC (case; n=50) were studied. Relative quantification of target miR-335 expression was examined using the comparative cycle threshold method. Their expression was correlated with different clinicopathological parameters. Fishers’ exact test, Student’s t-test, and Chi-square test were used as appropriate for data analysis. Kaplan-Meier methods were used to calculate overall and disease-free survival rate. Two sided P<0.05 was considered as significant. Results: miR-335 expression was found to be significantly low in GBC lesions when compared with GID lesions (P<0.001). The low expression level of miR-335 was correlated with histological grade (P=0.007), clinical stage (P<0.001), lymph node metastasis (P<0.001) and liver metastasis (P=0.016). Reduced expression of miRNA-335 was associated with a shorter median overall survival (7 months vs. 25 months) in GBC patients (P<0.001). Conclusions: Down regulation of miR-335 is associated with the severity of the disease and thus indicate that miR-335 expression may serve as prognostic marker for GBC.

Novel role of microRNA-126 in digestive system cancers: From bench to bedside

MicroRNAs (miRNAs) are ubiquitously expressed, small, non-coding RNAs that regulate the expression of approximately 30% of the human genes at the post-transcriptional level. miRNAs have emerged as crucial modulators in the initiation and progression of various diseases, including numerous cancer types. The high incidence rate of cancer and the large number of cancer-associated cases of mortality are mostly due to a lack of effective treatments and biomarkers for early diagnosis. Therefore there is an urgent requirement to further understand the underlying mechanisms of tumorigenesis. MicroRNA-126 (miR-126) is significantly downregulated in a number of tumor types and is commonly identified as a tumor suppressor in digestive system cancers (DSCs). miR-126 downregulates various oncogenes, including disintegrin and metalloproteinase domain-containing protein 9, v-crk sarcoma virus CT10 oncogene homolog and phosphoinositide-3-kinase regulatory subunit 2. These genes are involved in a number of tumor-associated signaling pathways, including angiogenesis, epithelial-mensenchymal transition and metastasis pathways. The aim of the current review was to summarize the role of miR-126 in DSCs, in terms of its dysregulation, target genes and associated signaling pathways. In addition, the current review has discussed the potential clinical application of miR-126 as a biomarker and therapeutic target for DSCs.

Overexpression of CrkL as a novel biomarker for poor prognosis in gastric cancer

BACKGROUND

The signaling adapter protein CrkL plays vital roles in multiple cancers. However, the expression pattern of CrkL protein and its clinical significance have not been well characterized in human gastric cancer (GC) so far.

OBJECTIVE

To investigate the association of tissue-based CrkL protein expression level with the clinicopathological characteristics and prognosis of GC patients.

METHODS

The expression level of CrkL protein in 380 GC patients was analyzed by immunohistochemistry. The associations of CrkL protein expression level with clinicopathologicalal characteristics and clinical outcome were evaluated.

RESULTS

Compared with the matched adjacent non-tumor tissues, CrkL protein expression level was significantly up-regulated in tumor tissues. In addition, there was a positive correlation between CrkL and Ki67 expression levels in GC patients. An elevated CrkL level statistically correlated with aggressive clinicopathologicalal characteristics, such as larger tumor size, deeper local invasion, more lymph node metastasis, advanced TNM stage, and poorer prognosis. Notably, multivariate analysis identified tissue-based CrkL level as an independent predictor for the unfavorable prognosis of GC.

CONCLUSIONS

These results indicate that CrkL protein may serve as a novel prognostic biomarker in GC.

Vasodilator-stimulated phosphoprotein (VASP), a novel target of miR-4455, promotes gastric cancer cell proliferation, migration, and invasion, through activating the PI3K/AKT signaling pathway

Background

MicroRNAs (miRNAs) are small non-coding RNAs which play important roles in the carcinogenesis of gastric cancer (GC). Expression profiling of miRNAs in paired gastric cancer and adjacent normal gastric tissues has demonstrated that miR-4455 is down-regulated in gastric cancer tissues, but its functional role in the carcinogenesis of GC had not previously been investigated.

Aims

The purpose of this study was to investigate the functional and biological mechanisms of miR-4455 in the progression of GC, in vitro.

Methods

Expression of miR-4455 was compared in human GC tissue samples and paired adjacent normal tissue samples. The in vitro effects of miR-4455 expression in MGC-803 cells on their proliferation, invasion, and migration were assessed by MTT assays and 5-bromo-2′-deoxyuridine staining, matrigel-invasion analysis and wound healing assays. Bioinformatics analysis (using PicTar, target scan and miRBase target) was used to identify potential targets for miR-4455, and the luciferase reporter assay, qRT-PCR and Western-blotting analyses were used to confirm VASP as the target of miR-4455. In addition, the effects of downregulation of VASP on the activation of PI3K/AKT signaling pathway were measured using Western-blot analysis.

Results

The expression of miR-4455 was markedly down-regulated in gastric cancer tissues vs. adjacent normal tissues, and miR-4455 expression inhibited the proliferation, invasion and migration of MGC-803 GC cells in vitro. Luciferase reporter assays revealed that miR-4455 inhibited VASP expression by targeting the 3′-UTR sequence of VASP. Furthermore, silencing of VASP markedly inhibited the activation of the PI3K/AKT signaling pathway.

Conclusion

Our results suggest that miR-4455 functions as a tumor suppressor in gastric cancer, by targeting VASP leading to activation of the PI3K/AKT signaling pathway and the inhibition of VASP mediated proliferation, migration and invasion of gastric cancer cells.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0573-4) contains supplementary material, which is available to authorized users.

miR-126: An indicator of poor prognosis and recurrence in histologically lymph node-negative gastric cancer

BACKGROUND

Few biomarkers are available for the prediction of prognosis and recurrence in lymph node (LN)-negative gastric cancer (GC) currently. miR-126 functions as a tumor suppressor in GC, however, its clinical significance in LN-negative GC remains unknown.

AIM

To investigate the associations of tissue miR-126 level with the clinicopathological characteristics and clinical outcome of LN-negative GC patients.

METHODS

Quantitative real-time polymerase chain reaction was performed to examine the tissue miR-126 level in 315 LN-negative GC patients who underwent curative gastrectomy with D2 lymphadenectomy. The associations of tissue miR-126 level with clinicopathological characteristics and clinical outcome were evaluated.

RESULTS

Compared with matched adjacent non-tumor tissues, miR-126 expression was significantly down-regulated in tumor tissues. A reduced tissue miR-126 level statistically correlated with aggressive clinicopathological characteristics, including larger tumor size, deeper local invasion, and poorer prognosis. Notably, multivariate analysis identified advanced T stage and low miR-126 level as independent predictors of the unfavorable prognosis and recurrence of LN-negative GC.

CONCLUSIONS

These results indicate for the first time that advanced T stage and low miR-126 level are predictors of unfavorable prognosis and recurrence in LN-negative GC patients. These parameters should be taken into account to stratify patients for adjuvant therapy and close follow-up.

Serum miR-126 level combined with multi- detector computed tomography in the preoperative prediction of lymph node metastasis of gastric cancer

BACKGROUND

Predicting lymph node metastasis (LNM) accurately is vital to design optimal treatment strategies preoperatively for gastric cancer (GC) patients. However, conventional tumor biomarkers and imaging techniques are not sufficient to predict LNM before surgery. miR-126 has been reported to play important roles in tumor metastasis which may represent a novel tumor biomarker.

OBJECTIVE

To assess the utility of the combination of serum miR-126 and multi-detector computed tomography (MDCT) in predicting LNM preoperatively in GC.

METHODS

Quantitative real-time polymerase chain reaction was performed to examine the serum miR-126 expression levels in 338 GC patients. MDCT was also performed. The cut-off value of preoperative serum miR-126 level for LNM was determined by receiver characteristic curve (ROC) analysis. Logistic regression analysis was used to determine independent predictors for LNM.

RESULTS

The serum miR-126 levels of GC patients with LNM were significantly lower compared with those without LNM (p< 0.05). In addition, the later the N stage was, the lower the serum miR-126 level was in GC patients (p< 0.05). With a cut-off value of 63.4, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of serum miR-126 for predicating LNM were 83.2%, 79.0%, 81.9%, 90.4% and 66.4%, respectively. The combination of serum miR-126 level and MDCT increased the accuracy of MDCT prediction for LNM from 69.2% to 86.7%. Serum miR-126 was an independent predictor for LNM.

CONCLUSIONS

These results indicate for the first time that the combination of serum miR-126 and MDCT is useful for the prediction of LNM in GC.