Transcriptional regulation of miR-224 upregulated in human HCCs by NFκB inflammatory pathways

Epigenetics of hepatocellular carcinoma: Role of microRNA

Hepatocellular carcinoma (HCC) represents a major form of primary liver cancer in adults. MicroRNAs (miRs), small non-coding single-stranded RNAs of 19-24 nucleotides in length, negatively regulate the expression of many target genes at the post-transcriptional and/or translational levels and play a critical role in the initiation and progression of HCC. In this review we have summarized the information of aberrantly expressed miRs in HCC, their mechanism of action and relationship to cancer. The recent advances in HCC research reveal that miRs regulate expression of various oncogenes and tumor suppressor genes, thereby contributing to the modulation of diverse biological processes including proliferation, apoptosis, epithelial to mesenchymal transition and metastasis. From a clinical viewpoint, polymorphisms within miR-binding sites are associated with the risk of HCC. Polymorphisms in miR related genes have been shown to correlate with survival or treatment outcome in patients. Furthermore, the review focuses on the potential role of miRs as novel biomarkers and their translational applications for diagnosis and therapy in HCC. With further insights into miR deregulation in HCC, it is expected that novel miR-based therapeutics will arise. Also, we orient the readers to other reviews that may provide better understanding of miR research in HCC.

Downregulation of microRNA-214 and overexpression of FGFR-1 contribute to hepatocellular carcinoma metastasis

miR-214 is one of the most significantly downregulated microRNAs (miRNAs) in hepatocellular carcinoma (HCC). Fibroblast growth factor receptor 1 (FGFR-1) is a miR-214 target gene implicated in the progression of HCC. However, the roles of miR-214 and FGFR-1 in HCC are not fully understood. Here, we analyzed the expression of miR-214 and FGFR-1 in 65 cases of HCC and paired non-neoplastic tissue specimens using real-time PCR and Western blot (WB), respectively. Our data indicated that miR-214 was downregulated and FGFR-1 was overexpressed in HCC compared to the paired non-neoplastic tissues. The low miR-214 expression was correlated with portal vein invasion (p=0.016) and early recurrence (p=0.045) in HCC patients. Moreover, the low miR-214 expression was correlated with high positive rate of FGFR-1 in HCC cases (p=0.020). Our data further demonstrated that miR-214 overexpression in SK-HEP1 and HepG2 cells downregulated FGFR-1 expression and inhibited liver cancer cell invasion. The Luciferase assay results further demonstrated the targeted regulation of FGFR-1 by miR-214. In conclusion, our data indicate that the downregulation of miR-214 in HCC and the upregulation of its target gene FGFR-1 is associated with HCC progression. Therefore, miR-214 and FGFR-1 are potential prognostic markers and therapeutic targets in HCC.

Identification of a microRNA expression signature for chemoradiosensitivity of colorectal cancer cells, involving miRNAs-320a, -224, -132 and let7g

BACKGROUND AND PURPOSE

Preoperative chemoradiotherapy (CRT) represents the standard treatment for locally advanced rectal cancer. Tumor response and progression vary considerably. MicroRNAs represent master regulators of gene expression, and may therefore contribute to this diversity.

MATERIAL AND METHODS

Genome-wide microRNA (miRNA) profiling was performed for 12 colorectal cancer (CRC) cell lines and an individual in vitro signature of chemoradiosensitivity was established. Functional relevance of selected miRNAs was established by transfecting miRNA-mimics into SW480 and SW837 cells. The prognostic value of selected miRNAs was assessed in 128 pretherapeutic patient biopsies.

RESULTS

Thirty-six miRNAs were identified to significantly correlate with sensitivity to CRT (Q < 0.05) including miR-320a and other miRNAs involved in the MAPK-, TGF- and Wnt-pathway. Transfection of selected miRNAs (let-7g, miR-132, miR-224, miR-320a) each induced a shift of sensitivity. High expression of let-7 g was associated with a good prognosis in rectal cancer patients (P = 0.03).

CONCLUSIONS

This is the first report of a miRNA expression signature for in vitro chemoradiosensitivity of CRC cell lines. Many of the identified miRNAs have not been linked to the response to CRT and may represent potential molecular targets to sensitize resistant cancers. If further validated, let7g expression may serve as predictive biomarker.

The complexity of NF-κB signaling in inflammation and cancer

The NF-κB family of transcription factors has an essential role in inflammation and innate immunity. Furthermore, NF-κB is increasingly recognized as a crucial player in many steps of cancer initiation and progression. During these latter processes NF-κB cooperates with multiple other signaling molecules and pathways. Prominent nodes of crosstalk are mediated by other transcription factors such as STAT3 and p53 or the ETS related gene ERG. These transcription factors either directly interact with NF-κB subunits or affect NF-κB target genes. Crosstalk can also occur through different kinases, such as GSK3-β, p38, or PI3K, which modulate NF-κB transcriptional activity or affect upstream signaling pathways. Other classes of molecules that act as nodes of crosstalk are reactive oxygen species and miRNAs. In this review, we provide an overview of the most relevant modes of crosstalk and cooperativity between NF-κB and other signaling molecules during inflammation and cancer.

MicroRNA-224 targets SMAD family member 4 to promote cell proliferation and negatively influence patient survival

MicroRNA-224 (miR-224) is frequently over-expressed in liver and colorectal cancers. We and others have previously described the role of miR-224 over-expression in cell proliferation in vitro but we have yet to identify the relevant miR-224 direct target. In this study, we further demonstrated that miR-224 up-regulation promotes cell proliferation using both in vitro assays and in vivo tumor growth models. We systematically screened for high confidence miR-224 targets by overlapping in silico predicted targets from multiple algorithms and significantly down-regulated genes in miR-224-expressing cells from whole genome expression microarrays. A total of 72 high confidence miR-224 targets were identified and found to be enriched in various cancer-related processes. SMAD family member 4 (SMAD4) is experimentally validated as the direct cellular target through which miR-224 promotes cell proliferation. The clinical relevance of our experimental observations was supported by a statistically significant inverse correlation between miR-224 and SMAD4 transcript expression in tumor versus paired adjacent non-tumorous tissues from HCC patients (p<0.001, r = −0.45, R² = 0.122). Furthermore, miR-224 up-regulation and SMAD4 down-regulation is significantly associated with poorer patient survival (p<0.05). In summary, miR-224/SMAD4 pathway is a clinically relevant pathway to provide new insights in understanding HCC. (191 words).

microRNA-224 promotes cell proliferation and tumor growth in human colorectal cancer by repressing PHLPP1 and PHLPP2

PURPOSE

To investigate the clinicopathologic significance, role, and mechanism of action of microRNA-224 (miR-224) in colorectal cancer.

EXPERIMENTAL DESIGN

Real-time PCR was used to quantify miR-224 expression. The association of miR-224 with the clinicopathologic features and survival was evaluated in 110 colorectal cancer patients. The role of miR-224 in colorectal cancer was investigated using in vitro and in vivo assays. Luciferase reporter assays were conducted to confirm target gene associations.

RESULTS

miR-224 was overexpressed in colorectal cancer. High-level expression of miR-224 was significantly associated with an aggressive phenotype and poor prognosis. Overexpression of miR-224 promoted colorectal cancer cell proliferation in vitro and tumor growth in vivo. Specifically, miR-224 accelerated the G1-S phase transition through activation of AKT/FOXO3a signaling, downregulation of p21Cip1 and p27Kip1, and upregulation of cyclin D1. Moreover, both PH domain leucine-rich-repeats protein phosphatase 1 (PHLPP1) and PHLPP2, antagonists of PI3K/AKT signaling, were confirmed as bona fide targets of miR-224. miR-224 directly targeted the 3'-untranslated regions of the PHLPP1 and PHLPP2 mRNAs and repressed their expression.

CONCLUSION

This study reveals functional and mechanistic links between miRNA-224 and the tumor suppressors PHLPP1 and PHLPP2 in the pathogenesis of colorectal cancer. miR-224 not only plays important roles in the regulation of cell proliferation and tumor growth in colorectal cancer, but also has potential as a prognostic marker or therapeutic target for colorectal cancer.

Transcriptional cooperation between p53 and NF-κB p65 regulates microRNA-224 transcription in mouse ovarian granulosa cells

MicroRNAs (miRNAs) have been indicated to play key roles in ovarian follicular development. However, little is known about how the miRNA gene expression itself is regulated in the mammalian ovary. We previously reported that miR-224 is involved in TGF-β1-mediated follicular granulosa cell (GC) growth and estradiol (E2) production by targeting Smad4. Here, the transcriptional regulation of miR-224 expression in GCs was further investigated. Our results showed that both the tumor suppressor gene p53 and NF-κB p65 subunit suppressed the TGF-β1-induced increase in pri-miR-224 expression in GCs. ChIP assays demonstrated that TGF-β1 enhanced the binding of p53 and p65 to the proximal promoter region of GABAA receptor ε subunit (miR-224 host gene). p53 and p65 transcriptionally cooperated to inactivate the GABAA receptor ε subunit promoter. In addition, p53/p65 could up-regulate Smad4 expression by inhibiting its target miR-224 in GCs which contributed, at least partially, to the effects of miR-224 and Smad4 on GC proliferation and E2 release. Our results provide new data about the interplay between transcription factors involved in GC proliferation and function by cooperatively regulating miRNA expression.

MicroRNAs in hepatocellular carcinoma: regulation, function, and clinical implications

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide and the third cause of cancer-related death. Poor understanding of the mechanisms underlying the pathogenesis of HCC makes it difficult to be diagnosed and treated at early stage. MicroRNAs (miRNAs), a class of noncoding single-stranded RNAs of ~22 nucleotides in length, posttranscriptionally regulate gene expression by base pairing with the 3' untranslated regions (3'UTRs) of target messenger RNAs (mRNAs). Aberrant expression of miRNAs is found in many if not all cancers, and many deregulated miRNAs have been proved to play crucial roles in the initiation and progression of cancers by regulating the expression of various oncogenes or tumor suppressor genes. In this Paper, we will summarize the regulations and functions of miRNAs aberrantly expressed in HCC and discuss the potential application of miRNAs as diagnostic and prognostic biomarkers of HCC and their potential roles in the intervention of HCC.

Non-coding RNAs in hepatitis B or C-associated hepatocellular carcinoma: potential diagnostic and prognostic markers and therapeutic targets

Non-coding RNA (ncRNA), a class of RNAs that do not code protein but have regulatory functions, can regulate gene expression and replication of hepatitis B virus or hepatitis C virus and play an important role in the virus-host interaction and the development of hepatocellular carcinoma (HCC). Deregulated ncRNAs in surgically removed hepatic tissues and circulation can be prognostic and diagnostic markers, respectively. ncRNAs functioning as either tumor suppressors or oncogenes can be therapeutic options. Here, we summarize the deregulated ncRNAs associated with the infections and HCC and focus on their roles on early diagnosis, prognosis prediction and therapeutic option of HCC.