[MicroRNA-s and their role in malignant hematologic diseases]

TERRA Gene Expression in Gastric Cancer: Role of hTERT

PURPOSE

One of the most important serious malignancies is gastric cancer (GC) with a high mortality globally. In this way, beside the environmental factors, genetic parameter has a remarkable effective fluctuation in GC. Correspondingly, telomeres are nucleoprotein structures measuring the length of telomeres and they have special potential in diagnosis of various types of cancers. Defect protection of the telomeric length initiates the instability of the genome during cancer, including gastric cancer. The most common way of maintaining telomere length is the function of the telomerase enzyme that replicates the TTAGGG to the end of the 3' chromosome.

METHODS

In this review, we want to discuss the alterations of hTERT repression on the modification of TERRA gene expression in conjunction with the importance of telomere and telomerase in GC.

RESULTS

The telomerase enzyme contains two essential components called telomerase reverse transcriptase (hTERT) and RNA telomerase (hTR, hTERC). Deregulation of hTERT plays a key role in the multistage process of tumorigenicity and anticancer drug resistance. The direct relationship between telomerase activity and hTERT has led to hTERT to be considered a key target for cancer treatment. Recent results show that telomeres are transcribed into telomeric repeat-containing RNA (TERRA) in mammalian cells and are long noncoding RNAs (lncRNAs) identified in different tissues. In addition, most chemotherapy methods have a lot of side effects on normal cells.

CONCLUSION

Telomere and telomerase are useful therapeutic goal. According to the main roles of hTERT in tumorigenesis, growth, migration, and cancer invasion, hTERT and regulatory mechanisms that control the expression of hTERT are attractive therapeutic targets for cancer treatment.

miR-29 promotes osteosarcoma cell proliferation and migration by targeting PTEN

Osteosarcoma (OS) is an aggressive malignant neoplasm that arises from primitively transformed cells of mesenchymal origin, and that exhibits osteoblastic differentiation and produces malignant osteoid. MicroRNAs (miRNAs) have been widely reported to have important regulatory roles in various human tumors, including OS. However, the potential mechanism of miR-29 in OS remains largely unknown. miR-29 was highly expressed in OS and overexpression of miR-29 promoted OS cell proliferation, as well as proliferating cell nuclear antigen (PCNA) expression and migration, whereas lower expression of miR-29 inhibited OS cell proliferation, PCNA expression and migration. In the present study, a dual-luciferase reporter system supporting phosphatase and tensin homolog (PTEN) was a target of miR-29 and its expression was inhibited by miR-29 mimic, but increased by miR-29 inhibitor. Overexpression of PTEN inhibited OS cell proliferation and migration and it could attenuate miR-29 promotion effect on OS progression. Overall, the results revealed that miR-29, as a tumor promoter, is involved in OS progression and metastasis by targeting PTEN, indicating that the miR-29/PTEN pathway is a potential therapeutic target for the treatment of OS.

OncomiR or antioncomiR: Role of miRNAs in Acute Myeloid Leukemia

Acute Myeloid Leukemia (AML) is a hematopoietic progenitor/stem cell disorder in which neoplastic myeloblasts are stopped at an immature stage of differentiation and lost the normal ability of proliferation and apoptosis. MicroRNAs (miRNAs) are small noncoding, single-stranded RNA molecules that can mediate the expression of target genes. While miRNAs mean to contribute the developments of normal functions, abnormal expression of miRNAs and regulations on their corresponding targets have often been found in the developments of AML and described in recent years. In leukemia, miRNAs may function as regulatory molecules, acting as oncogenes or tumor suppressors. Overexpression of miRNAs can down-regulate tumor suppressors or other genes involved in cell differentiation, thereby contributing to AML formation. Similarly, miRNAs can down-regulate different proteins with oncogenic activity as tumor suppressors. We herein review the current data on miRNAs, specifically their targets and their biological function based on apoptosis in the development of AML.

Upregulated in Hepatitis B virus-associated hepatocellular carcinoma cells, miR-331-3p promotes proliferation of hepatocellular carcinoma cells by targeting ING5

Hepatitis B virus (HBV) is a major risk factor for development and progression of hepatocellular carcinoma (HCC). It has been reported that viral infection can interfere with cellular microRNA (miRNA) expression and participate in the pathogenesis of oncogenicity. Our miRNAs array data indicated that miR-331-3p expression in HCC cell lines increased, but the relationship between miR-331-3p expression and HBV activity is unclear. Here, we observed elevated expression of miR-331-3p in different HCC cell lines expressing HBV. HBV, especially HBx, promotes miR-331-3p expression by enhancing its promoter activity. Using a miRNA target prediction database miRBase, we identified ING5 to be a novel target gene of miR-331-3p. miR-331-3p could inhibit ING5 expression by directly targeting its 3′-untranslated region (3′-UTR). As predicted, HBV was confirmed to repress ING5 at both mRNA and protein levels by promoting miR-331-3p expression. Our result indicated that miR-331-3p expression promotes proliferation of SMMC7721 cells by inhibiting ING5. ING5 overexpression promoted cell apoptosis in HCC cell lines. We also found ING5 expression was decreased in tumor tissue of HCC patient with HBV infection compared to its expression in para-carcinoma tissues. Conclusion: These results showed that miR-331-3p is upregulated by HBV and promotes proliferation of HCC cells though repression of ING5 expression. These data provide new insights for understanding the mechanisms of HBV-related HCC pathogenesis.

MiR-221 increases osteosarcoma cell proliferation, invasion and migration partly through the downregulation of PTEN

Increasing evidence has demonstrated that microRNAs (miRNAs or miRs) are involved in cancer initiation and progression. Previous studies have indicated that miR-221 is one of the most consistently overexpressed miRNAs in multiple types of cancer. However, the role of miR-221 in osteosarcoma carcinogenesis and progression is not yet fully understood. Thus, the aim of the present study was to examine the expression of miR-221 in osteosarcoma and to determine the effects of miR-221 on the biological behavior of osteosarcoma cells. RT-qPCR revealed that the expression of miR-221 was significantly upregulated in the osteosarcoma tissues and osteosarcoma cell lines (p<0.05). In order to explore the role of miR-221 in osteosarcoma, the expression of miR-221 in the human osteosarcoma cell line MG‑63 was upregulated or downregulated by transfection with miR-221 mimic or miR-221 inhibitor, respectively. The results from RT-qPCR revealed that we had successfully generated MG‑63 cells in which miR-221 was either overexpressed or depleted. To investigate the effects of miR-221 on osteosarcoma cell proliferation, invasion and migration, a tetrazolium-based colorimetric assay, propidium iodide (PI) staining, a transwell migration assay and a wound healing assay were used in the present study. The results revealed that the proliferation, invasion and migration ability of the MG‑63 cells in which miR-221 was overexpressed was enhanced, and the proliferation, invasion and migration ability of the MG‑63 cells in which miR-221 was depleted was suppressed. The correlation between miR-221 and phosphatase and tensin homolog (PTEN) expression was investigated by RT-qPCR and western blot analysis. The results revealed that the downregulation of miR-221 significantly increased the expression of PTEN, whereas the upregulation of miR-221 significantly reduced the expression of PTEN. Taken together, our results suggest that miR-221 enhances the proliferation, invasion and migration ability of osteosarcoma cells partly by suppressing PTEN.

Non-coding RNAs and gastric cancer

Non-coding RNAs (ncRNAs) play key roles in development, proliferation, differentiation and apoptosis. Altered ncRNA expression is associated with gastric cancer occurrence, invasion, and metastasis. Moreover, aberrant expression of microRNAs (miRNAs) is significantly related to gastric cancer tumor stage, size, differentiation and metastasis. MiRNAs interrupt cellular signaling pathways, inhibit the activity of tumor suppressor genes, and affect the cell cycle in gastric cancer cells. Some miRNAs, including miR-21, miR-106a and miR-421, could be potential markers for the diagnosis of gastric cancer. Long non-coding RNAs (lncRNAs), a new research hotspot among cancer-associated ncRNAs, play important roles in epigenetic, transcriptional and post-transcriptional regulation. Several gastric cancer-associated lncRNAs, such as CCAT1, GACAT1, H19, and SUMO1P3, have been explored. In addition, Piwi-interacting RNAs, another type of small ncRNA that is recognized by gastroenterologists, are involved in gastric carcinogenesis, and piR-651/823 represents an efficient diagnostic biomarker of gastric cancer that can be detected in the blood and gastric juice. Small interfering RNAs also function in post-transcriptional regulation in gastric cancer and might be useful in gastric cancer treatment.

Up-regulated MicroRNA-181a induces carcinogenesis in hepatitis B virus-related hepatocellular carcinoma by targeting E2F5

Background

Accumulating evidence showed that microRNAs are involved in development and progression of multiple tumors. Recent studies have found that miR-181a were dysregulated in several types of cancers, however, the function of miR-181a in hepatocellular carcinoma (HCC) remains unclear. In this study we assessed the potential association between miR-181a, HBV and HCC.

Methods

The expression of miR-181a in HBV-expressing cells was determined by using qRT-PCR. Dual-Luciferase reporter Assay, qRT-PCR and western blot were performed to investigate the target genes of miR-181a. The effects of miR-181a on HCC proliferation were analyzed by MTS and colony formation assay. Tumor growth assay was used to analyze the effect of miR-181a on tumor formation.

Results

HBV up-regulated miR-181a expression by enhancing its promoter activity. Overexpression of miR-181a in hepatoma cells promoted cell growth in vitro and tumor formation in vivo. Conversely, inhibition of miR-181a suppressed the proliferation of HBV-expressing cells. Mechanism investigation revealed that miR-181a inhibited the expression of transcription factor E2F5 by specifically targeting its mRNA 3′UTR. Moreover, E2F5 inhibition induced cell growth and rescued the suppressive effect of miR-181a inhibitor on the proliferation of SMMC-7721 cells. Interestingly, we also discovered that HBV could down-regulate E2F5 expression.

Conclusions

Those results strongly suggested that HBV down-regulated E2F5 expression, in part, by up-regulating the expression of miR-181a. Up-regulation of miR-181a by HBV in hepatoma cells may contribute to the progression of HCC possibly by targeting E2F5, suggesting miR-181a plays important role in HCC development.

MicroRNA 181a improves proliferation and invasion, suppresses apoptosis of osteosarcoma cell

MicroRNA 181a (miR-181a) was found dysregulated in a variety of human cancers and significantly associated with clinical outcome of cancer patients. However, the direct role of miR-181a has not yet been characterized in osteosarcoma progression. This study was aimed at investigating the effects of miR-181a on osteosarcoma cell biological behavior. First, the expression of miR-181a in osteosarcoma cell lines (MG63, HOS, SaOS-2, and U2OS) and a human osteoblastic cell line (hFOB1.19) was detected by qRT-PCR. Results showed that miR-181a was overexpressed in osteosarcoma cell lines compared to human osteoblastic cell line (hFOB1.19). To investigate the effects of miR-181a on proliferation, apoptosis, and invasion of osteosarcoma cells, we generated human osteosarcoma MG63 cells in which miR-181a was either overexpressed or depleted. The MG63 cell viability, cycle, apoptosis, and invasive ability were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide staining, propidium iodide (PI) staining, Annexin V-FITC/PI double staining, and Transwell invasion experiment, respectively. The results showed that MG63 cell viability, proliferation, and invasive abilities were suppressed, and the apoptosis was enhanced in the group with underexpression of miR-181a. The viability, proliferation, and invasive abilities were improved, and the apoptosis was inhibited in the group with overexpression of miR-181a. The results from Western blotting indicated that miR-181a might be associated with the up-regulation of bcl-2 and matrix metalloproteinase 9 and the down-regulation of tissue inhibitor of metalloproteinases-3 and p21 in MG63 cells. Taken together, our results suggested that miR-181a might facilitate proliferation and invasion and suppress apoptosis of osteosarcoma cells, which might be a potential target for the treatment of osteosarcoma.