Circulating Plasma Levels of miR-20b, miR-29b and miR-155 as Predictors of Bevacizumab Efficacy in Patients with Metastatic Colorectal Cancer. Int J Mol Sci. 2018;19. [PMID: 29361687 PMCID: PMC5796251 DOI: 10.3390/ijms19010307]

Whole transcriptome sequencing identifies crucial genes associated with colon cancer and elucidation of their possible mechanisms of action

PURPOSE

This study aimed to investigate the key long non-coding RNAs (lncRNAs) associated with colon cancer and elucidate their possible mechanisms of action.

PATIENTS AND METHODS

Eight early-stage (ES) colon tumor tissues, eight late-stage (LS) colon tumor tissues, and eight normal tissues were collected, and they were subjected to high-throughput RNA sequencing. Subsequently, comprehensive bioinformatics analyses, including the identification of differentially expressed mRNAs and lncRNAs, functional enrichment analysis, and construction of a protein-protein interaction network and an miRNA-lncRNA-mRNA regulatory network were performed. Additionally, the expression of key lncRNAs was verified using real-time quantitative PCR (qPCR).

RESULTS

In total, 549 common differentially expressed mRNAs and 30 common differentially expressed lncRNAs were identified in both the ES and LS colon cancer samples upon comparison with the normal samples. Functional enrichment analysis showed that KIAA0125 was significantly enriched in the PI3K-Akt signaling pathway and that MSTRG.35002.1 was markedly enriched in BMP signaling-related functions. Moreover, key miRNA-lncRNA-mRNA relationships, such as hsa-miR-29b-3p-KIAA0125-BCL2 and hsa-miR-29b-3p-MSTRG.35002.1-MMP2, were identified. Notably, the qPCR assay confirmed that KIAA0125 and MSTRG.35002.1 were significantly downregulated in both ES and LS colon tumor tissues compared with normal colon tissues.

CONCLUSION

Our findings indicate that key lncRNAs, including KIAA0125 and MSTRG.35002.1, may be involved in colorectal cancer (CRC) development. Downregulation of KIAA0125 may contribute to CRC development via sponging of hsa-miR-29b-3p to regulate BCL2 expression or regulating the PI3K-Akt signaling pathway. Downregulation of MSTRG.35002.1 may promote CRC development via sponging of hsa-miR-29b-3p to regulate MMP2 expression or regulating the BMP signaling pathway.

Expression of Circulating miR-155, miR-21, miR-221, miR-30a, miR-34a and miR-29a: Comparison of Colonic and Rectal Cancer

BACKGROUND

Colorectal cancer is an increasing cause of death. Circulating microRNAs (miRs) could be great diagnostic and prognostic biomarkers of colorectal cancer, but further continuation of their utility is needed for their comprehensive application.

MATERIALS AND METHODS

Twenty-seven patients with colonic cancer, 16 with rectal cancer and 12 healthy volunteers as controls, were involved in this study. Expression of miR-155, miR-21, miR-221, miR-30a, miR-34a and miR-29a were determined by reverse transcription polymerase chain reaction (RT-PCR) from sera of patients.

RESULTS

Expression of miR-155, miR-21 and miR-221 was significantly higher in rectal cancer than in colonic cancer. There was no difference found between those with TNM1 cancer and controls for both cancer types. miR-155, miR-34a and miR-29a were down-regulated in all patients with cancer compared to controls. We did not find any statistically significant up-regulation of miR-221 in patients with colonic cancer compared to controls. In contrast, in patients with rectal cancer, miR-221 expression was higher than in controls. Advanced stage was also linked to higher miR-221 expression compared to early stage. Slight, but statistically significant increase was observed in miR-30a expression in patients with colon cancer compared to control individuals.

CONCLUSION

Our results partly support previous findings. Here we report on differences in the expression of circulating microRNA between colonic and rectal tumours for the first time.

MiR-106a-5p promotes 5-FU resistance and the metastasis of colorectal cancer by targeting TGFβR2

BACKGROUND

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths. 5-Fluorouracil (5-FU)-based chemotherapy has always been the first-line treatment. However, development of 5-FU resistance seriously affects its curative effect. The aim of this study was to elucidate the molecular mechanisms of 5-FU resistance through miR-106a-5p in CRC.

METHODS

Colorectal cancer tissues were collected to analyze miR-106a-5p and TGFβR2 expressions by qPCR. Functional experiments for evaluating cell survival and metastasis were conducted to observe the biological effects of miR-106a-5p and TGFβR2. The cell survival rate was calculated using an MTT assay; the metastasis was confirmed with a Transwell invasion assay and Western blotting, which we used to measure the expression levels of the epithelial-mesenchymal transition (EMT) markers E-cadherin and vimentin. The combination of miR-106a to TGFβR2 was predicted using Targetscan, and confirmed through the construction of the luciferase reporter plasmid pGL3-basic. The interplay between miR-106a-5p and TGFβR2 was tested with qPCR and Western blotting. A Spearman rank analysis was employed to verify the correlation of miR-106a-5p and TGFβR2 expressions.

RESULTS

MiR-106a-5p was up-regulated and TGFβR2 was down-regulated in 5-FU resistant CRC tissues and HT-29 cells. MiR-106a-5p promoted cell survival and suppressed the apoptosis rate and caspase 3 activity. Additionally, cell invasion was promoted by miR-106a-5p overexpression in the HT-29 cells and was inhibited by miR-106a-5p knockdown in the 5-FU resistant HT-29 cells; miR-106a-5p overexpression contributed to migration by increasing vimentin expression and by decreasing E-cadherin expression in the HT-29 cells; miR-106a-5p functioned by directly binding to TGFβR2. The TGFβR2 knockdown conferred chemoresistance of 5-FU and metastasis in 5-FU resistant HT-29 cells, and TGFβR2 overexpression reduced cell survival, invasion numbers, vimentin expression, and increased the cell apoptosis rate and caspase 3 activity in 5-FU resistant HT-29 cells. Also, miR-106a-5p negatively regulated TGFβR2 in a linear correlation way in the CRC tissues.

CONCLUSION

The up-regulation of miR-106a-5p contributes to the pathomechanism of colorectal cancer by promoting 5-FU resistance and metastasis via inhibiting target TGFβR2. Our findings provide new promising ways for the clinical application of the TGFβR2-miR-106a axis in clinical chemotherapy for 5-FU resistant colorectal cancer.

Relevance of MicroRNAs as Potential Diagnostic and Prognostic Markers in Colorectal Cancer

Colorectal cancer (CRC) is currently the third and the second most common cancer in men and in women, respectively. Every year, more than one million new CRC cases and more than half a million deaths are reported worldwide. The majority of new cases occur in developed countries. Current screening methods have significant limitations. Therefore, a lot of scientific effort is put into the development of new diagnostic biomarkers of CRC. Currently used prognostic markers are also limited in assessing the effectiveness of CRC therapy. MicroRNAs (miRNAs) are a promising subject of research especially since single miRNA can recognize a variety of different mRNA transcripts. MiRNAs have important roles in epigenetic regulation of basic cellular processes, such as proliferation, apoptosis, differentiation, and migration, and may serve as potential oncogenes or tumor suppressors during cancer development. Indeed, in a large variety of human tumors, including CRC, significant distortions in miRNA expression profiles have been observed. Thus, the use of miRNAs as diagnostic and prognostic biomarkers in cancer, particularly in CRC, appears to be an inevitable consequence of the advancement in oncology and gastroenterology. Here, we review the literature to discuss the potential usefulness of selected miRNAs as diagnostic and prognostic biomarkers in CRC.

The Dual Role of MicroRNAs in Colorectal Cancer Progression

Colorectal cancer (CRC) is responsible for one of the major cancer incidence and mortality worldwide. It is well known that MicroRNAs (miRNAs) play vital roles in maintaining the cell development and other physiological processes, as well as, the aberrant expression of numerous miRNAs involved in CRC progression. MiRNAs are a class of small, endogenous, non-coding, single-stranded RNAs that bind to the 3’-untranslated region (3′-UTR) complementary sequences of their target mRNA, resulting in mRNA degradation or inhibition of its translation as a post-transcriptional regulators. Moreover, miRNAs also can target the long non-coding RNA (lncRNA) to regulate the expression of its target genes involved in proliferation and metastasis of CRC. The functions of these dysregulated miRNAs appear to be context specific, with evidence of having a dual role in both oncogenes and tumor suppression depending on the cellular environment in which they are expressed. Therefore, the unique expression profiles of miRNAs relate to the diagnosis, prognosis, and therapeutic outcome in CRC. In this review, we focused on several oncogenic and tumor-suppressive miRNAs specific to CRC, and assess their functions to uncover the molecular mechanisms of tumor initiation and progression in CRC. These data promised that miRNAs can be used as early detection biomarkers and potential therapeutic target in CRC patients.

Circulating microRNAs as potential cancer biomarkers: the advantage and disadvantage

MicroRNAs are endogenous single-stranded non-coding small RNA molecules that can be secreted into the circulation and exist stably. They usually exhibit aberrant expression under different physiological and pathological conditions. Recently, differentially expressed circulating microRNAs were focused on as potential biomarkers for cancer screening. We herein review the role of circulating microRNAs for cancer diagnosis, tumor subtype classification, chemo- or radio-resistance monitoring, and outcome prognosis. Moreover, circulating microRNAs still have several issues hindering their reliability for the practical clinical application. Future studies need to elucidate further potential application of circulating microRNAs as specific and sensitive markers for clinical diagnosis or prognosis in cancers.