MicroRNA regulation network in colorectal cancer metastasis

Colorectal Cancer: Disease Process, Current Treatment Options, and Future Perspectives

Colorectal cancer (CRC) is one of the deadliest malignancies in the US, ranking fourth after lung, prostate, and breast cancers, respectively, in general populations. It continues to be a menace, and the incidence has been projected to more than double by 2035, especially in underdeveloped countries. This review seeks to provide some insights into the disease progression, currently available treatment options and their challenges, and future perspectives. Searches were conducted in the PubMed search engine in the university's online library. The keywords were "Colorectal Cancer" AND "disease process" OR "disease mechanisms" OR "Current Treatment" OR "Prospects". Selection criteria were original articles published primarily during the period of 2013 through 2023. Abstracts, books and documents, and reviews/systematic reviews were filtered out. Of over 490 thousand articles returned, only about 800 met preliminary selection criteria, 200 were reviewed in detail, but 191 met final selection criteria. Fifty-one other articles were used due to cross-referencing. Although recently considered a disease of lifestyle, CRC incidence appears to be rising in countries with low, low-medium, and medium social demographic indices. CRC can affect all parts of the colon and rectum but is more fatal with poor disease outcomes when it is right-sided. The disease progression usually takes between 7-10 years and can be asymptomatic, making early detection and diagnosis difficult. The CRC tumor microenvironment is made up of different types of cells interacting with each other to promote the growth and proliferation of the tumor cells. Significant advancement has been made in the treatment of colorectal cancer. Notable approaches include surgery, chemotherapy, radiation therapy, and cryotherapy. Chemotherapy, including 5-fluorouracil, irinotecan, oxaliplatin, and leucovorin, plays a significant role in the management of CRC that has been diagnosed at advanced stages. Two classes of monoclonal antibody therapies have been approved by the FDA for the treatment of colorectal cancer: the vascular endothelial growth factor (VEGF) inhibitor, e.g., bevacizumab (Avastin®), and the epidermal growth factor receptor (EGFR) inhibitor, e.g., cetuximab (Erbitux®) and panitumumab (Verbitix®). However, many significant problems are still being experienced with these treatments, mainly off-target effects, toxic side effects, and the associated therapeutic failures of small molecular drugs and the rapid loss of efficacy of mAb therapies. Other novel delivery strategies continue to be investigated, including ligand-based targeting of CRC cells.

Circulating exosomal miRNAs as a promising diagnostic biomarker in cancer

Cancer belongs to multifactorial diseases characterized by uncontrolled growth and proliferation of abnormal cells. Breast cancer, non-small cell lung cancer, and colorectal cancer are the most frequently diagnosed malignancies with a high mortality rate. These carcinomas typically contain multiple genetically distinct subpopulations of tumor cells leading to tumor heterogeneity, which promotes the aggressiveness of the disease. Early diagnosis is necessary to increase patient progression-free survival. Particularly, miRNAs present in exosomes derived from tumors represent potential biomarkers suitable for early cancer diagnosis. Identification of miRNAs by liquid biopsy enables a personalized approach with the subsequent better clinical management of patients. This review article highlights the potential of circulating exosomal miRNAs in early breast, non-small cell lung, and colorectal cancer diagnosis.

Novel insights on perils and promises of miRNA in understanding colon cancer metastasis and progression

Colorectal cancer (CRC) is the third highest frequent malignancy and ultimate critical source of cancer-associated mortality around the world. Regardless of latest advances in molecular and surgical targeted medicines that have increased remedial effects in CRC patients, the 5-year mortality rate for CRC patients remains dismally low. Evidence suggests that microRNAs (miRNAs) execute an essential part in the development and spread of CRC. The miRNAs are a type of short non-coding RNA that exhibited to control the appearance of tumor suppressor genes and oncogenes. miRNA expression profiling is already being utilized in clinical practice as analytical and prognostic biomarkers to evaluate cancer patients' tumor genesis, advancement, and counteraction to drugs. By modulating their target genes, dysregulated miRNAs are linked to malignant characteristics (e.g., improved proliferative and invasive capabilities, cell cycle aberration, evasion of apoptosis, and promotion of angiogenesis). This review presents an updated summary of circulatory miRNAs, tumor-suppressive and oncogenic miRNAs, and the potential reasons for dysregulated miRNAs in CRC. Further we will explore the critical role of miRNAs in CRC drug resistance.

Non-coding RNAs are correlated to TGF-β receptor type 2 in patients with colorectal cancer

BACKGROUND

Multiple molecular expression alterations, particularly in non-coding RNAs, play fundamental roles in the regulations of cellular processes and may relate to the occurrence and progression of colorectal cancer (CRC). In the present study, we investigated the associations between TGFBR2, miR20a-5p and long non-coding RNA (lncRNA) LAMTOR5-AS1 in CRC patients.

METHODS

Colorectal cancer and adjacent normal tissue samples (n = 34) were prepared from CRC patients. The associations between TGFBR2, miR20a-5p and lncRNA LAMTOR5-AS1 were predicted using bioinformatics tools. The expression levels of TGFBR2, miR20a-5p and lncRNA LAMTOR5-AS1 were measured using a quantitative real-time polymerase chain reaction technique. The TGFBR2 protein values were measured by western blotting. The clinical importance of lncRNA LAMTOR5-AS1 was assessed using receiver operating characteristic curve.

RESULTS

The up-regulated levels of TGFBR2 (p = 0.02), TGFBR2 protein (p = 0.008) and lncRNA LAMTOR5-AS1 (p = 0.02) were significantly observed in CRC tissues compared to the adjacent normal tissues. The miR20a-5p expression level (p = 0.009) was downregulated in CRC tissues. In addition, the miR20a-5p expression level was inversely correlated to the TGFBR2 gene (r²  = 0.88, p < 0.0001), protein (r²  = 0.95, p < 0.0001) and lncRNA LAMTOR5-AS1 gene (r²  = 0.93, p < 0.0001) expression levels. Based on the area under curve, the increase of lncRNA LAMTOR5-AS1 expression level with a sensitivity of 64.52% and specificity of 65.52% was considered in CRC patients.

CONCLUSIONS

We propose that miR20a-5p is inversely related to long non-coding RNA (lncRNA) LAMTOR5-AS, such that it may be involved in the regulation of TGFBR2 expression level in CRC patients.

Recombinant water stress protein 1 (Re-WSP1) suppresses colon cancer cell growth through the miR-539/β-catenin signaling pathway

BACKGROUND

Nostoc commune Vauch. is a nitrogen-fixing blue-green algae that expresses a large number of active molecules with medicinal properties. Our previous study found that a water stress protein (WSP1) from N. commune and its recombinant counterpart (Re-WSP1) exhibited significant anti-colon cancer activity both in vitro and in vivo. This study is to investigate the effects of Re-WSP1 on proliferation of colon cancer cells and to elucidate the relevant mechanisms.

METHODS

Real-time quantitative PCR was used to detect the expression of miR-539 in colon cancer HT-29 and DLD1 cells. Colon cancer cells were transfected with miR-539 mimics and negative controls, and cell proliferation were detected by CCK8 and clonogenic assays. The target gene of miR-539 was predicted, and the dual luciferase reporter gene experiment was used to verify the target gene. After colon cancer cells were transfected with miR-539 mimics or inhibitors, the expression of target gene β-catenin was detected by Western blot. miR-539 inhibitor confirmed cell proliferation.

RESULTS

Re-WSP1 inhibited colon cancer cell growth in a dose-dependent manner. Re-WSP1 inhibited the expression of β-catenin, which was partly reversed by LiCl treatment. Quantitative PCR analysis showed that the expression of miR-539 was significantly upregulated after Re-WSP1 treatment. Moreover, miR-539 negatively regulated the expression of β-catenin by directly binding to the 3'UTR of β-catenin mRNA. The cell growth inhibition and the decrease in β-catenin expression induced by Re-WSP1 were significantly reversed by miR-539 inhibitor.

CONCLUSION

Re-WSP1 suppresses colon cancer cell growth via the miR-539/β-catenin axis.

Biological Implications and Clinical Potential of Metastasis-Related miRNA in Colorectal Cancer

Colorectal cancer (CRC), ranking as the third commonest cancer, leads to extremely high rates of mortality. Metastasis is the major cause of poor outcome in CRC. When metastasis occurs, 5-year survival rates of patients decrease sharply, and strategies to enhance a patient's lifetime seem limited. MicroRNAs (miRNAs) are evolutionarily conserved small non-coding RNAs that are significantly involved in manipulation of CRC malignant phenotypes, including proliferation, invasion, and metastasis. To date, accumulating studies have revealed the mechanisms and functions of certain miRNAs in CRC metastasis. However, there is no systematic discussion about the biological implications and clinical potential (diagnostic role, prognostic role, and targeted therapy potential) of metastasis-related miRNAs in CRC. This review mainly summarizes the recent advances of miRNA-mediated metastasis in CRC. We also discuss the clinical values of metastasis-related miRNAs as potential biomarkers or therapeutic targets in CRC. Moreover, we envisage the future orientation and challenges in translating these findings into clinical applications.

Clinical Potentials of miR-576-3p, miR-613, NDRG2 and YKL40 in Colorectal Cancer Patients

Introduction:

Colorectal cancer (CRC) is the most common type of gastrointestinal tract cancers. This investigation aim was to assess the expression of miR-576-3p and miR-613 in CRC patients in addition to NDRG2 and YKL40 serum levels determination to decide their diagnostic and prognostic significance.

Methods:

Sixty early diagnosed CRC patients prior to any treatment in addition to twelve healthy subjects were enrolled in this study. Blood samples were taken from subjects and allowed for clotting and centrifugation, then the collected sera were stored at -80ºC till it were used for detection of our molecular biomarkers. The mature miRNAs expressions (miR-576-3p and miR-613) were detected in serum by qRT-PCR, while NDRG2 and YKL40 serum levels were determined by ELISA. In addition, the correlation of the measured parameters with the clinicopathological data of the patients was investigated.

Results:

The study results showed that both miRNA-576-3p and miRNA-613 were down-regulated in CRC patients with fold change 0.33, 0.36; respectively. A significant positive correlation was observed between miR-576-3p and miR-613 (r = 0.75, p < 0.001). NDRG2 serum levels were decreased in patients compared to the control group but the decrease wasn’t statistically significant. On the other hand, it was observed that YKL40 serum level was significantly increased in CRC patients compared to control (p-value < 0.001). Furthermore, YKL40 showed a very high diagnostic value (AUC = 0.97, specificity = 91.7%, sensitivity = 96%, p-value = 0.0001).

Conclusion:

The observations of this investigation concluded that, the expressions of miR-576-3p and miR-613 in addition to YKL40 serum levels determinations may help in the diagnosis of CRC.

MiR-1260b inhibitor enhances the chemosensitivity of colorectal cancer cells to fluorouracil by targeting PDCD4/IGF1

Colorectal cancer (CRC) is the most common malignant tumor type and has become resistant to 5-fluorouracil (5-FU) in recent decades, which is one of the most popular therapies. Recently, microRNA (miRNA or miR) has been investigated as a potential therapeutic strategy for CRC. However, there has been little investigation of the underlying mechanism of the association between expression of miRNA and chemosensitivity. The present study aimed to investigate the effect of miR-1260b inhibitor on CRC cells, and their chemosensitivity to 5-FU, by treating them with the miR-1260b inhibitor. miR-1260b inhibitor was demonstrated to significantly promote the proliferation and invasion of the CRC cell line, HCT116, and to increase the apoptotic rate. Furthermore, it was validated that programmed cell death 4 (PDCD4) was a direct target of miR-1260b inhibitor in CRC with bioinformatics tools and a luciferase assay. Western blot analysis revealed that miR-1260b inhibitor could significantly decrease PDCD4 expression, and downregulate the expression of phosphorylated-Akt (p-Akt) and phosphorylated-extracellular-signal-regulated kinase (p-ERK). In conclusion, it was confirmed that the anti-tumor effect of the miR-1260b inhibitor was conducted by blocking the phosphorylated 3-kinase/Akt pathway as dysregulated protein expression induced by miR-1260b inhibitor was rescued by insulin-like growth factor. Notably, miR-1260b inhibitor could significantly enhanced the chemoresponse of HCT116 cells to 5-FU via reduced proliferation, increased apoptosis, and downregulation of PDCD4, p-Akt and p-ERK protein expression. In summary, the present study may provide a novel direction for future clinical therapy to enhance the chemosensitivity of tumor cells.

miR-223 increases gallbladder cancer cell sensitivity to docetaxel by downregulating STMN1

Background

MicroRNAs (miRs) are involved in cancer carcinogenesis, and certain regulatory miRs could provide promising therapeutic methods for refractory malignancies, such as gallbladder cancer (GBC). miR-223 was found to play a pivotal role in enhancing chemotherapeutic effects, therefore evoking interest in the role of miR-223 in GBC.

Results

miR-223 was decreased in GBC tissues and cell lines, and ectopic miR- 223 expression exhibited multiple anti-tumorigenic effects in GBC cells, including decreased proliferation, migration and invasion in vitro. However, treatment with a miR-223 inhibitor increased cell viability. We determined that STMN1 was negatively correlated with and regulated by miR-223 in GBC. miR-223 increased GBC sensitivity to docetaxel in vitro and in vivo, and the induced sensitivity to docetaxel was suppressed by the restoration of STMN1 expression.

Methods

We examined miR-223 expression in GBC tissue and GBC cell lines using qRT-PCR. The effects of modulated miR-223 expression in GBC cells were assayed using Cell Counting Kit-8 (CCK8), flow cytometry, and wound-healing and invasion assays. Susceptibility to docetaxel was evaluated in miR-223/STMN1-modulated GBC cells and xenograft tumor models. The protein expression of relevant genes was examined by Western blotting.

Conclusions

These findings indicated that miR-223 might serve as an onco-suppressor that enhances susceptibility to docetaxel by downregulating STMN1 in GBC, highlighting its promising therapeutic value.

Decoding colorectal cancer epigenomics

Colorectal cancer (CRC) is very heterogeneous and presents different types of epigenetic alterations including DNA methylation, histone modifications and microRNAs. These changes are considered as characteristics of various observed clinical phenotypes. Undoubtedly, the discovery of epigenetic pathways with novel epigenetic-related mechanisms constitutes a promising advance in cancer biomarker discovery. In this review, we provide an evidence-based discussing of the current understanding of CRC epigenomics and its role in initiation, epithelial-to-mesenchymal transition and metastasis. We also discuss the recent findings regarding the potential clinical perspectives of these alterations as potent biomarkers for CRC diagnosis, prognosis, and therapy in the era of liquid biopsy.

miR-539 inhibits human colorectal cancer progression by targeting RUNX2

Emerging evidence has shown that microRNAs (miRNAs) such as miR-539 play critical roles in carcinogenesis and progression in many types of cancer, including human colorectal cancer (CRC). However, the roles and underlying mechanism of miR-539 in CRC have not been well identified. The aims of this study were, therefore, to investigate the regulatory role and potential mechanism of miR-539 in human CRC. Here, we show that miR-539 expression is downregulated in CRC tissues and cell lines. The expression level of miR-539 is inversely associated with advanced clinical stage and lymph node metastasis. In vitro studies reveal that overexpression of miR-539 inhibits CRC cell proliferation and colony formation as well as migration and invasion; in vivo results demonstrate that overexpression of miR-539 dramatically reduces CRC xenograft tumor growth. Moreover, runt-related transcription factor 2 (RUNX2), a known oncogene, was identified as a target transcript of miR-539 in CRC by bioinformatic analysis, luciferase reporter assay, qPCR, and western blotting. RUNX2 expression levels were upregulated and inversely correlated with miR-539 expression in CRC tissues. Importantly, overexpression of RUNX2 without the 3'-untranslated region that is targeted by miR-539 partially reversed the inhibitory effect of miR-539 on CRC cell proliferation, migration, and invasion. Collectively, these findings demonstrate that miR-539 functions as a tumor suppressor in CRC, at least in part, by targeting RUNX2, supporting the targeting of the novel miR-539 as a potentially effective therapeutic approach for treatment of CRC.

MicroRNA-30a Inhibits Colorectal Cancer Metastasis Through Down-Regulation of Type I Insulin-Like Growth Factor Receptor

BACKGROUND

miR-30a expression is down-regulated and regulates tumor suppressors in various cancers.

AIM

We investigated the mechanisms underlying the biological role of miR-30a in CRC.

METHODS

MicroRNA, mRNA, and protein expression were analyzed by quantitative real-time PCR and Western blot. The migration and invasion abilities of CRC were determined by wound healing assay, and trans-well migration and invasion. A luciferase reporter assay was used to confirm the targets of miR-30a.

RESULTS

miR-30a expression was significantly down-regulated in CRC tissues and in CRC tissue with lymph node metastasis compared to CRC tissue without metastasis. Overexpression of miR-30a suppressed migration and invasion through insulin-like growth factor 1 receptor (IGF1R) in CRC cells. miR-30a suppresses IGF1R protein expression and inhibits β-catenin or p-AKT and increases E-cadherin expression. The IGF1R expression level is also up-regulated in CRC tumors and inversely correlated with miR-30a in CRC specimens.

CONCLUSIONS

miR-30a functions as a tumor-suppressive miRNA, which may provide a therapeutic strategy for metastasis of CRC.

Epistasis analysis of microRNAs on pathological stages in colon cancer based on an Empirical Bayesian Elastic Net method

Background

Colon cancer is a leading cause of worldwide cancer death. It has become clear that microRNAs (miRNAs) play a role in the progress of colon cancer and understanding the effect of miRNAs on tumorigenesis could lead to better prognosis and improved treatment. However, most studies have focused on studying differentially expressed miRNAs between tumor and non-tumor samples or between stages in tumor tissue. Limited work has conducted to study the interactions or epistasis between miRNAs and how the epistasis brings about effect on tumor progression. In this study, we investigate the main and pair-wise epistatic effects of miRNAs on the pathological stages of colon cancer using datasets from The Cancer Genome Atlas.

Results

We develop a workflow composed of multiple steps for feature selection based on the Empirical Bayesian Elastic Net (EBEN) method. First, we identify the main effects using a model with only main effect on the phenotype. Second, a corrected phenotype is calculated by removing the significant main effect from the original phenotype. Third, we select features with epistatic effect on the corrected phenotype. Finally, we run the full model with main and epistatic effects on the previously selected main and epistatic features. Using the multi-step workflow, we identify a set of miRNAs with main and epistatic effect on the pathological stages of colon cancer. Many of miRNAs with main effect on colon cancer have been previously reported to be associated with colon cancer, and the majority of the epistatic miRNAs share common target genes that could explain their epistasis effect on the pathological stages of colon cancer. We also find many of the target genes of detected miRNAs are associated with colon cancer. Go Ontology Enrichment Analysis of the experimentally validates targets of main and epistatic miRNAs, shows that these target genes are enriched for biological processes associated with cancer progression.

Conclusion

Our results provide a set of candidate miRNAs associated with colon cancer progression that could have potential translational and therapeutic utility. Our analysis workflow offers a new opportunity to efficiently explore epistatic interactions among genetic and epigenetic factors that could be associated with human diseases. Furthermore, our workflow is flexible and can be applied to analyze the main and epistatic effect of various genetic and epigenetic factors on a wide range of phenotypes.

Electronic supplementary material

The online version of this article (10.1186/s12864-017-4130-7) contains supplementary material, which is available to authorized users.

Empty Spiracles Homeobox 2 (EMX2) Inhibits the Invasion and Tumorigenesis in Colorectal Cancer Cells

Empty spiracles homeobox 2 (EMX2) is a homeodomain-containing transcription factor that plays an essential role in tumorigenesis. However, to the best of our knowledge, the role of EMX2 in human colorectal cancer (CRC) is still unclear. Thus, the aim of this study was to investigate the expression and role of EMX2 in CRC. Our results demonstrated that the expression of EMX2 was greatly decreased in CRC tissues and cell lines. Overexpression of EMX2 significantly inhibited the proliferation in vitro and CRC tumor growth in nude mice. In addition, EMX2 also inhibited the migration and invasion of CRC cells. Mechanically, overexpression of EMX2 downregulated the expression levels of β-catenin, cyclin D1, and c-Myc in CRC cells. Taken together, our study demonstrates that EMX2 inhibits proliferation and tumorigenesis through inactivation of the Wnt/β-catenin pathway in CRC cells. Therefore, EMX2 may be a potential therapeutic target for the treatment of CRC.

MicroRNA-613 targets FMNL2 and suppresses progression of colorectal cancer

Increasing evidence indicates that dysregulation of miRNAs is involved in the initiation and progression of colorectal cancer (CRC). MicroRNA (miR)-613 has been reported to function as a tumor suppressor in many cancers. However, the precise role of miR-613 in CRC progression is unclear. This study aimed to investigate the role and underlying mechanism of miR-613 in growth and metastasis of CRC. Real-time quantitative PCR (qPCR) and western blot techniques were used to assess expression of miR-613 and formin-like 2 (FMNL2) in CRC cell lines and tissues. Luciferase reporter assays were conducted to investigate the association between miR-613 and FMNL2. Proliferation, wound healing, and transwell invasion assays, as well as flow cytometric analysis, were performed to evaluate the effect of miR-613 on proliferation, migration, invasion, and cell-cycle status, respectively, of CRC cells. We found that miR-613 was significantly downregulated in CRC cell lines and tissue samples, and correlated closely with TNM stage. miR-613 suppressed CRC cell proliferation, migration, and invasion, and induced cell-cycle arrest at G1 phase. FMNL2 was identified as a direct target of miR-613 in CRC cells. Importantly, FMNL2 overexpression rescued miR-613-induced suppression of proliferation, migration, and invasion of CRC cells. These results suggest that miR-613 functions as a tumor suppressor in the progression of CRC by regulating FMNL2.

Adenomatous polyposis coli (APC) regulates miR17-92 cluster through β-catenin pathway in colorectal cancer

Adenomatous polyposis coli (APC) mutation is the most common genetic change in sporadic colorectal cancer (CRC). Although deregulations of miRNAs have been frequently reported in this malignancy, APC-regulated miRNAs have not been extensively documented. Here, by using an APC-inducible cell line and array analysis, we identified a total of 26 deregulated miRNAs. Among them, members of miR-17-92 cluster were dramatically inhibited by APC and induced by enforced expression of β-catenin. Furthermore, we demonstrate that activated β-catenin resulted from APC loss binds to and activates the miR-17-92 promoter. Notably, enforced expression of miR-19a overrides APC tumor suppressor activity, and knockdown of miR-19a in cancer cells with compromised APC function reduced their aggressive features in vitro. Finally, we observed that expression of miR-19a significantly correlates with β-catenin levels in colorectal cancer specimens, and it is associated to the aggressive stage of tumor progression. Thus, our study reveals that miR-17-92 cluster is directly regulated by APC/β-catenin pathway and could be a potential therapeutic target in colon cancers with aberrant APC/β-catenin signaling.

Roles and mechanisms of action of microRNAs in colorectal cancer

MicroRNAs (miRNAs) are a class of endogenous, evolutionarily conserved small non-coding RNAs, which play a vital role in tumour formation, development, metastasis and recurrence by inducing DNA methylation, changing tumor microenvironment and regulating signal pathways such as Wnt/β-catenin, phosphoinositide3-kinase (PI3K), K-RAS, epithelial mesenchymal transitions (EMT) and so on. Recent studies have found that the expression of many miRNAs is dyregulated in colorectal cancer, and they participate in and control the formation and development of colorectal cancer. Thus, understanding the roles and mechanisms of action of miRNAs in colorectal cancer can provide a new avenue for its early diagnosis, clinical staging, treatment and prognosis evaluation.

miR-143 suppresses the proliferation of NSCLC cells by inhibiting the epidermal growth factor receptor

MicroRNAs (miRs) regulate the proliferation and metastasis of numerous cancer cell types. It was previously reported that miR-143 levels were downregulated in non-small cell lung cancer (NSCLC) tissues and cell lines, and that the migration and invasion of NSCLC cells was inhibited upon suppression of cell proliferation and colony formation by the upregulation of miR-143. Epidermal growth factor receptor (EGFR), which is a vital factor in the promotion of cancer cell proliferation and has been investigated as a potential focus in cancer therapy, has been reported to be a possible target of miR-143. The present study aimed to investigate the role of miR-143 in NSCLC using NSCLC cell lines and primary cells from NSCLC patients. NSCLC cells were co-transfected with EGFR and miR-143, and the mRNA and protein expression of EGFR were analyzed. Furthermore, the activity of the transfected cancer cells with regard to colony formation, migration, invasion and apoptosis were evaluated. The levels of miR-143 were decreased in the NSCLC cell lines and primary cells from patients with NSCLC compared with the controls. Following transfection with miR-143, the ability of NSCLC cells to proliferate, form colonies, migrate and invade was inhibited. Similarly, knockdown of EGFR led to the suppression of NSCLC cell proliferation. The mRNA and protein expression levels of EGFR were significantly reduced following miR-143 overexpression, and the level of miR-143 was inversely correlated with that of EGFR in NSCLC cells. The results of the present study demonstrated that miR-143 was able to suppress NSCLC cell proliferation and invasion by inhibiting the effects of EGFR, suggesting that EGFR may be considered a potential target for NSCLC therapy.

miR-122 inhibits cancer cell malignancy by targeting PKM2 in gallbladder carcinoma

Gallbladder cancer (GBC) is one of the lethal diseases of digestive system. Increasing evidence prompt that microRNAs (miRs) might provide a novel therapeutical target for malignant disease. The antitumor effect of miR-122 to GBC is worth to be investigated. miR-122 expression level in GBC tissue sample and cell lines were assayed by qRT-PCR. miR-122 mimics were transfected for upregulation of miR-122 expression. Cell function was assayed by CCK8, flow cytometry, wound healing assay, migration assay, and invasion assay. The target genes of miR-122 were predicated by TargetScan online program and verified by western blot and luciferase report gene assay. miR-122 was decreased in GBC tissue and cell lines. The exogenous introduction of miR-122 exhibits multiple antitumor effect in GBC cell proliferation, invasion, and metastasis. Further studies revealed that the PKM2 was a regulative target of miR-122 in GBC cell. miR-122 also inhibits TGF-β-induced epithelium mesenchymal transformation of GBC cell by downregulating PKM2 expression. These findings suggest that miR-122 plays an important role in tumorigenesis of GBC through interfering PKM2, highlighting its usefulness as a potential therapeutic agent in GBC.

MicroRNA‑205 promotes the tumorigenesis of nasopharyngeal carcinoma through targeting tumor protein p53-inducible nuclear protein 1

Nasopharyngeal carcinoma (NPC) is a common type of cancer in southern China, miRNAs have been shown to be involved in the tumorigenesis of multiple cancer types. The present study aimed to explore the potential role of miR‑205 in NPC. Reverse transcription quantitative polymerase chain reaction was used to determine the expression levels of miR‑205 in 20 fresh NPC specimens and 20 normal nasopharyngeal tissues. The function of miR‑205 in the proliferation, migration, invasion and apoptosis of NPC‑derived cells was detected by MTT assay, colony formation assay, wound healing assay, Transwell assay and flow cytometry. Furthermore, a target gene of miR‑205 was identified using the luciferase reporter assay. The expression of miR‑205 was increased in NPC tissues compared with that in normal tissues. Overexpression of miR‑205 was found to promote the proliferation, migration and invasion of NPC‑derived cells, while apoptosis was suppressed. Tumor protein p53-inducible nuclear protein 1 was identified as a target gene of miR‑205. Overall, the present study demonstrated that miR‑205 may function as an oncogene in NPC tumorigenesis.

Upregulation of nucleostemin in colorectal cancer and its effects on cell malignancy

Objective

Nucleostemin (NS) is a new protein localized in the nucleolus of most stem cells and tumor cells, which regulates their self-renewal and cell cycle progression. The aim of this study was to investigate the expression of NS in colorectal cancer (CRC) and the effects of NS knockdown in the Sw620 cell line to provide basis for clinical target therapy.

Methods

NS expression in 372 patients with CRC and 367 normal participants was assessed using immunohistochemistry. The expression level of NS gene was evaluated by polymerase chain reaction. Then, the relationship among NS expression, clinicopathological features, and prognosis was analyzed. Silencing of NS expression was achieved by using NS-specific small-interfering RNAs. The viability and growth rate of Sw620 cells were determined by proliferation and invasion assays. Cell cycle distribution of the cells was analyzed by flow cytometry.

Results

High NS expression was positively related with node metastasis, distant metastasis, and TNM stage. In Kaplan–Meier survival analysis, patients with low NS expression always had significantly longer survival time than those with high expression. Moreover, our results showed that knockdown of NS expression inhibited proliferation and viability of Sw620 cells in a time-dependent manner. Cell cycle studies revealed that NS depletion resulted in G1 cell cycle arrest at short times of transfection (24 hours), followed with apoptosis at longer times (48 hours and 72 hours), suggesting that post-G1 arrest apoptosis occurred in Sw620 cells.

Conclusion

Overall, these results point to the essential role of NS in Sw620 cells; thus, this gene might be considered a promising target for treatment of CRC.

MicroRNAs as potential drug targets for therapeutic intervention in colorectal cancer

INTRODUCTION

MicroRNAs (miRNAs) are small (19 - 22 nucleotide), non-protein-coding RNA segments that function as master regulators of hundreds of genes simultaneously in both normal and malignant cells. In colorectal cancer (CRC) miRNAs are deregulated and have critical roles in initiation and progression of CRC by interacting with various oncogenes and tumor suppressor genes including APC, KRAS and p53, or by modulating downstream signal transduction pathways. Numerous promising miRNAs have emerged as potential drug targets for therapeutic intervention and possible candidates for replacement therapy in CRC.

AREAS COVERED

In this review the authors summarize the available information on miRNAs and their role in CRC. The authors point out specific miRNAs as potential drug targets and those having a significant role in gene activation and gene silencing during the process of CRC development, to highlight their importance as possible therapeutic candidates for the treatment of CRC.

EXPERT OPINION

Targeting miRNAs provides an emerging opportunity to develop effective miRNA-based replacement therapy or antagonists to alter expression in colon cancer patient tumors. However, the biggest challenge is to overcome obstacles associated with pharmacokinetics, delivery and toxicity in order to translate the potential of miRNAs into efficacious anticancer drugs.

miR-612 negatively regulates colorectal cancer growth and metastasis by targeting AKT2

Colorectal cancer (CRC) is one of the most common cancers worldwide, with a particularly high incidence in developed countries. Distant metastasis and recurrence are the main causes of CRC-related deaths. MicroRNAs (miRNAs) in the serum make them potential biomarkers for cancers, as reported in serum or tumor tissues from CRC patients. In this study, we found that miR-612 expression was significantly lower in CRC tissues or cells compared with peritumor tissues or normal cells, and lower in metastatic CRC specimens compared with non-metastatic specimens, whereas AKT2 exhibited opposite trend. Gain-of-function and loss-of-function assays showed that miR-612 inhibited CRC cell proliferation and migration in vitro by Cell Counting Kit-8 and transwell assays. Further analysis revealed that miR-612 directly suppressed AKT2, which in turn inhibited the downstream epithelial–mesenchymal transition-related signaling pathway. These results were additionally validated in vivo by tumorigenesis and liver metastasis experiments. The results of this study suggested a critical role of miR-612 in the development of CRC.

MicroRNA-409-3p suppresses colorectal cancer invasion and metastasis partly by targeting GAB1 expression

Colorectal cancer (CRC) is one of the most common cancers worldwide and its metastasis accounts for the majority of deaths. However, the molecular mechanisms underlying CRC progression are not well characterized. In this study, we identified miR-409-3p as a tumor suppressor of CRC. MiR-409-3p expression was significantly downregulated in CRC tissue compared to adjacent non-tumor tissue, and reduced miR-409-3p expression was correlated with CRC metastasis. In vitro and in vivo studies revealed that miR-409-3p negatively regulated CRC metastatic capacities, including suppressing cancer cell migration, invasion and metastasis. To explore the mechanism of action of miR-409-3p, we adopted a pathway and pathophysiological event-based target screening and validation approach, and found nine known metastasis-related genes as potential targets. The 3'-UTR binding assays between the candidates and miR-409-3p suggested that only GAB1, NR4A2 and LMO4 were directly regulated by the miRNA. However, endogenous expression analysis revealed that only GAB1 was modulated by miR-409-3p in CRC cells at both the mRNA and protein levels. Furthermore, we provided evidence to conclude that GAB1 was partially responsible for miR-409-3p-mediated metastasis. Taken together, our data demonstrate that miR-409-3p is a metastatic suppressor, and post-transcriptional inhibition of the oncoprotein GAB1 is one of the mechanisms of action of this miRNA. Our finding suggests miR-409-3p might be a novel target for CRC metastasis treatment.

Differential expressions of cancer-associated genes and their regulatory miRNAs in colorectal carcinoma

Colorectal cancer is one of the frequently seen malignancies in the world. To date, several oncogenes and tumor suppressor genes have been identified and linked to colorectal cancer pathogenesis. Although recent advances in the diagnosis and therapy of colorectal cancer are promising, identifying novel genetic contributors is still high priority. In the present study, expression profile of some cancer-related genes and their regulatory miRNA molecules were evaluated by using a high-throughput real-time PCR method. For the study, a total of 54 patients diagnosed with CRC and normal colon tissue samples of 42 healthy controls were included. For the expression analysis, total RNA was extracted from FFPE tissue samples and converted to cDNA. All expression analyses were assessed by using Fluidigm Microfluidic Dynamic Array chips for 96 samples and the reactions were held in Fluidigm BioMark™ HD System Real-Time PCR. As a result of the study, expression of the ADAMTS1, FHIT, RUNX1, RUNX3 and WWOX genes was shown to be significantly altered in CRC tissues in contrast to normal tissue samples. Moreover, miR-378a-3p, miR-155-5p, miR-193b-3p, miR-96-5p, miR-17-5p, miR-27a-3p, miR-133b, miR-203a, miR-205-5p, miR-34c-5p, miR-130a-3p, miR-301a-3p, miR-132-3p, miR-222-3p, miR-34a-5p, miR-21-5p, miR-29a-3p and miR-29b-3p were found to be significantly deregulated in CRC. Consequently, results of the current study strongly suggest the involvement of novel cancer-related genes and their regulatory miRNAs in CRC physiopathology.

microRNAs and Colorectal Cancer

Colorectal cancer (CRC) is one of the most common types of human cancer with high cancer-related morbidity and mortality rates. The development and clinical validation of novel therapeutic avenues have improved the clinical outcome, but metastatic CRC still remains an incurable disease in most cases. The interest in discovering novel pathophysiological drivers in CRC is intensively ongoing and the search for novel biomarkers for early diagnosis, for patient's stratification for prognostic purposes or for predicting treatment response are warranted. microRNAs are small RNA molecules that regulate the expression of larger messenger RNA species by different mechanisms with the final consequence to provide a fine tuning tool for global gene expression patterns. First discovered in worms, around 15 years ago it became clear that microRNAs are also existing in humans and that they are widely involved in human carcinogenesis. Within the last years, tremendous progress in the understanding of microRNAs and their role in CRC carcinogenesis has been developed. In this book chapter, several examples of previously identified microRNAs and how they influence colorectal carcinogenesis will be discussed. The information starting at the underlying molecular mechanisms towards clinical applications will be depicted and an overview what great potential these small molecules might carry in future colorectal cancer medicine, will be discussed.