Hongwei Liang

INTRODUCTION: ERBB3, one of the four members of the ErbB family of receptor tyrosine kinases, plays an important role in breast cancer etiology and progression. In the present study, we aimed to identify novel miRNAs that can potentially target ERBB3 and their biological functions. METHOD: The expression levels of miR-143/145 and target mRNA were examined by relative quantification RT-PCR, and the expression levels of target protein were detected by Western blot. We used bioinformatic analyses to search for miRNAs that can potentially target ERBB3. Luciferase reporter plasmids were constructed to confirm direct targeting. Furthermore, the biological consequences of the targeting of ERBB3 by miR-143/145 were examined by cell proliferation and invasion assays in vitro and by the mouse xenograft tumor model in vivo. RESULTS: We identified an inverse correlation between miR-143/145 levels and ERBB3 protein levels, but not between miR-143/145 levels and ERBB3 mRNA levels, in breast cancer tissue samples. We identified specific targeting sites for miR-143 and miR-145 (miR-143/145) in the 3'-untranslated region (3'-UTR) of the ERBB3 gene and regulate ERBB3 expression. We demonstrated that the repression of ERBB3 by miR-143/145 suppressed the proliferation and invasion of breast cancer cells, and that miR-143/145 showed an anti-tumor effect by negatively regulating ERBB3 in the xenograft mouse model. Interestingly, miR-143 and miR-145 showed a cooperative repression of ERBB3 expression and cell proliferation and invasion in breast cancer cells, such that the effects of the two miRNAs were greater than with either miR-143 or miR-145 alone. CONCLUSION: Taken together, our findings provide the first clues regarding the role of the miR-143/145 cluster as a tumor suppressor in breast cancer through the inhibition of ERBB3 translation. These results also support the idea that different miRNAs in a cluster can synergistically repress a given target mRNA.

The detection of exogenous plant microRNAs in human/animal plasma/sera lies at the foundation of exploring their cross-kingdom regulatory functions. It is necessary to establish a standard operation procedure to promote study in this nascent field. In this study, 18 plant miRNAs were assessed in watermelon juice and mixed fruits by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). CT values, no-template controls and standard curves for each miRNA were used to evaluate the specificity and sensitivity of qRT-PCR and to obtain concentrations. Sixteen miRNAs were selected and measured in human plasma from volunteers after drinking juice. The CT values of 6 plant miRNAs in human plasma fell outside the linear ranges of their standard curves. The remaining 10 miRNAs were present at high basal levels, and 6 of them showed a dynamic physiological pattern in plasma (absorption rates of 0.04% to 1.31%). Northern blotting was used to confirm the qRT-PCR results. Critical issues such as RNA extraction and internal controls were also addressed.

BACKGROUND: Colorectal cancer (CRC) is a severe health problem worldwide. Clarifying the mechanisms for the deregulation of oncogenes and tumour suppressors in CRC is vital for its diagnosis, treatment, prognosis and prevention. Hu antigen R (HuR), which is highly upregulated in CRC, functions as a pivotal oncogene to promote CRC progression. However, the underlying cause of its dysregulation is poorly understood. METHODS: In CRC tissue sample pairs, HuR protein levels were measured by Western blot and immunohistochemical (IHC) staining, respectively. HuR mRNA levels were also monitored by qRT-PCR. Combining meta-analysis and microRNA (miRNA) target prediction software, we predicted miRNAs that targeted HuR. Pull-down assay, Western blot and luciferase assay were utilized to demonstrate the direct binding of miR-22 on HuR's 3'-UTR. The biological effects of HuR and miR-22 were investigated both in vitro by CCK-8, EdU and Transwell assays and in vivo by a xenograft mice model. JASPAR and SABiosciences were used to predict transcriptional factors that could affect miR-22. Luciferase assay was used to explore the validity of putative Jun binding sites for miR-22 regulation. ChIP assay was performed to test the Jun's occupancy on the C17orf91 promoter. RESULTS: We observed a significant upregulation of HuR in CRC tissue pairs and confirmed the oncogenic function of HuR both in vitro and in vivo. We found that an important tumour-suppressive miRNA, miR-22, was significantly downregulated in CRC tissues and inversely correlated with HuR in both CRC tissues and CRC cell lines. We demonstrated that miR-22 directly bound to the 3'-UTR of HuR and led to inhibition of HuR protein, which repressed CRC proliferation and migration in vitro and decelerated CRC xenografted tumour growth in vivo. Furthermore, we found that the onco-transcription factor Jun could inhibit the transcription of miR-22. CONCLUSIONS: Our findings highlight the critical roles of the Jun/miR-22/HuR regulatory axis in CRC progression and may provide attractive potential targets for CRC prevention and treatment.

microRNAs (miRNAs) have emerged as major regulators of the initiation and progression of human cancers, including breast cancer. The aim of this study is to determine the expression pattern of miR-96 in breast cancer and to investigate its biological role during tumorigenesis. We showed that miR-96 was significantly upregulated in breast cancer. We then investigated its function and found that miR-96 significantly promoted cell proliferation, migration and invasion in vitro and enhanced tumor growth in vivo. Furthermore, we explored the molecular mechanisms by which miR-96 contributes to breast cancer progression and identified PTPN9 (protein tyrosine phosphatase, non-receptor type 9) as a direct target gene of miR-96. Finally, we showed that PTPN9 had opposite effects to those of miR-96 on breast cancer cells, suggesting that miR-96 may promote breast tumorigenesis by silencing PTPN9. Taken together, this study highlights an important role for miR-96 in the regulation of PTPN9 in breast cancer cells and may provide insight into the molecular mechanisms of breast carcinogenesis.