Ya-Ping Ye

MicroRNA-30b functions as a tumour suppressor in human colorectal cancer by targeting KRAS, PIK3CD and BCL2

Colorectal cancer (CRC) is the third most common cancer in the USA. MicroRNAs play important roles in the pathogenesis of CRC. In this study, we investigated the role of miR‐30b in CRC and found that its expression was significantly lower in CRC tissues than that in normal tissues. We showed that a low expression level of miR‐30b was closely related to poor differentiation, advanced TNM stage and poor prognosis of CRC. Further experiments showed that over‐expression of miR‐30b suppressed CRC cell proliferation in vitro and tumour growth in vivo. Specifically, miR‐30b promoted G1 arrest and induced apoptosis. Moreover, KRAS, PIK3CD and BCL2 were identified as direct and functional targets of miR‐30b. MiR‐30b directly targeted the 3′‐untranslated regions of their mRNAs and repressed their expression. This study revealed functional and mechanistic links between miRNA‐30b and oncogene KRAS, PIK3CD and BCL2 in the pathogenesis of CRC. MiR‐30b not only plays important roles in the regulation of cell proliferation and tumour growth in CRC, but is also a potential prognostic marker or therapeutic target for CRC. Restoration of miR‐30b expression may represent a promising therapeutic approach for targeting malignant CRC. Copyright

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. Clin Cancer Res; 19(17); 4662–72. ©2013 AACR.

FOXC2 promotes colorectal cancer proliferation through inhibition of FOXO3a and activation of MAPK and AKT signaling pathways.

Abnormal expression of FOXC2 has been found in several human cancers. However, the role of FOXC2 in the progression of colorectal cancer (CRC) has not been well characterized. In analysis of 206 CRC specimens, we revealed that both high expression and nuclear localization of FOXC2 were correlated to aggressive characteristics and poor survival of patients with CRC. FOXC2 promoted cell proliferation through activation of MAPK and AKT pathways, subsequently down-regulating p27, up-regulating cyclin D1 and p-FOXO3a. Furthermore, FOXC2 nuclear localization was required for its promotion of cell proliferation. These findings suggest that FOXC2 plays an essential role in CRC progression and may serve as a valuable clinical prognostic marker of this disease.

MicroRNA-224 sustains Wnt/β-catenin signaling and promotes aggressive phenotype of colorectal cancer

BackgroundGrowing evidence suggests that Wnt/β-catenin pathway plays an important role in CRC development, progression and metastasis. Aberrant miR-224 expression has been reported in CRC. However, the mechanism of miR-224 promotes both proliferation and metastatic ability largely remains unclear.MethodsReal-time PCR was used to quantify miR-224 expression. Luciferase reporter assays were conducted to confirm the activity of Wnt/β-catenin pathway and target gene associations, and immunofluorescence staining assay was performed to observe the nuclear translocation of β-catenin. Bioinformatics analysis combined with in vivo and vitro functional assays showed the potential target genes, GSK3β and SFRP2, of miR-224. Specimens from forty patients with CRC were analyzed for the expression of miR-224 and the relationship with GSK3β/SFRP2 by real-time PCR and western blot.ResultsBioinformatics and cell luciferase function studies verified the direct regulation of miR-224 on the 3’-UTR of the GSK3β and SFRP2 genes, which leads to the activation of Wnt/β-catenin signaling and the nuclear translocation of β-catenin. In addition, knockdown of miR-224 significantly recovered the expression of GSK3β and SFRP2 and attenuated Wnt/β-catenin-mediated cell metastasis and proliferation. The ectopic upregulation of miR-224 dramatically inhibited the expression of GSK3β/SFRP2 and enhanced CRC proliferation and invasion.ConclusionOur research showed mechanistic links between miR-224 and Wnt/β-catenin in the pathogenesis of CRC through modulation of GSK3β and SFRP2.

MiR-384 inhibits human colorectal cancer metastasis by targeting KRAS and CDC42

Colorectal cancer (CRC) is the third most common cancer worldwide. Metastatic progression is a primary factor contributing to lethality of CRC patients. However, the molecular mechanisms forming early local invasion and distant metastatic colonies are still unclear and the present therapeutic approaches for CRC are unsatisfactory. Therefore, novel therapies targeting metastatic invasion that could prevent tumor spreading and recurrence are urgently needed. Our study showed that the decrease of miR-384 was found in 83.0% (83/100) CRC patients. And low-leveled expression of miR-384 was closely correlated with the invasive depth, lymph node and distant metastasis of CRC. Overexpression of miR-384 could inhibit the invasive and migrating abilities of CRC cells in vitro and the metastatic potential in vivo. Luciferase assays showed that miR-384 repressed the expression of Kirsten Ras (KRAS) and Cell division cycle 42 (CDC42) by directly targeting their 3’-untranslated regions. There is functional and mechanistic relationship between miRNA-384 and KRAS, CDC42 in the invasion and metastasis of CRC. And our findings suggest that miR-384could be a potent therapeutic target for CRC. Restoration of miR-384 expression might provide novel therapeutic approach to the reduction of CRC metastasis.

Metastasis-Associated in Colon Cancer-1 Associates With Poor Prognosis and Promotes Cell Invasion and Angiogenesis in Human Cervical Cancer.

Objective The aim of this study is to investigate the clinicopathologic significance and potential role of metastasis-associated in colon cancer-1 (MACC1) in the progression of cervical cancer. Methods MACC1 expression was examined in cervical cancer cell lines, 6 matched cervical cancer tissues, and adjacent noncancerous tissues using Western blotting and real-time reverse transcriptase polymerase chain reaction. MACC1 protein expression and localization were determined in 181 paraffin-embedded archived cervical cancer samples using immunohistochemistry. Statistical analyses were applied to evaluate the clinicopathologic significance. The effects of MACC1 on cell migration, invasion, and angiogenesis were examined using migration assay, wound healing assay, 3-dimensional morphogenesis assay, and chicken chorioallantoic membrane assay. Western blotting was performed to examine the impact of MACC1 on the Akt and nuclear factor &kgr;B signaling pathways. Results Both protein and messenger RNA levels of MACC1 was up-regulated in cervical cancer cell lines and cervical cancer tissues, as compared with normal tissues. High MACC1 expression was detected in 96 (53%) of 181 of the cervical cancer tissues. In addition, high MACC1 expression correlated significantly with aggressiveness of cervical cancer, including International Federation of Gynecology and Obstetric stage (P = 0.001), pelvic lymph node metastasis (P = 0.004), recurrence (P = 0.037), and poor survival (P = 0.001). Moreover, enforced expression of MACC1 in cervical cancer cell lines significantly enhanced cell migration, invasion, and angiogenesis. Conversely, knockdown of MACC1 caused an inhibition of cell migration, invasion, and angiogenesis. Up-regulation of MACC1 increased, but knockdown of MACC1 decreased the expression of matrix metalloproteinase-2 and matrix metalloproteinase-9. Furthermore, enforced expression of MACC1 could enhance, but knockdown of MACC1 could reduce AKT and nuclear factor &kgr;B pathway activity. Conclusions Our findings suggest that MACC1 protein, as a valuable marker of cervical cancer prognosis, plays an important role in the progression of human cervical cancer cells.

TLE4 promotes colorectal cancer progression through activation of JNK/c-Jun signaling pathway

The Groucho transcriptional co-repressor TLE4 protein has been shown to be a tumor suppressor in a subset of acute myeloid leukemia. However, little is known about its role in development and progression of solid tumor. In this study, we found that the expression of TLE4 in colorectal cancer (CRC) tissues was significantly higher than that in their matched adjacent intestine epithelial tissues. In addition, high expression of TLE4 was significantly correlated with advanced Dukes stage, lymph node metastasis and poor prognosis of CRC. Moreover, enforced expression of TLE4 in CRC cell lines significantly enhanced proliferation, invasion and tumor growth. On the contrary, knock down of TLE4 repressed cell proliferation, invasion and tumor growth. Furthermore, our study exhibited that the TLE4 promoted cell proliferation and invasion partially via activation of JNK-c-Jun pathway and subsequently increased cyclinD1 and decreased P27Kip1 expression. In conclusion, these results suggested that TLE4, a potential prognostic biomarker for CRC, plays an important role in the development and progression of human CRC.

The tumor-suppressor gene LZTS1 suppresses colorectal cancer proliferation through inhibition of the AKT-mTOR signaling pathway.

The Leucine zipper tumor suppressor gene 1 (LZTS1/FEZ1) gene was originally identified as a potential tumor suppressor. However, the expression pattern and the role of LZTS1 in the progression of colorectal cancer (CRC) have not been well characterized. Herein, we reported that LZTS1 was markedly reduced in CRC tissues compared with matched adjacent normal intestine epithelial tissues. In analysis of 160 CRC specimens, we revealed that decreased expression of LZTS1 was correlated to aggressive characteristics and poor survival of patients with CRC. Moreover, we found that expression of LZTS1 in CRC cells significantly inhibited cell proliferation in vitro and prohibited tumor growth in vitro. On the contrary, silence of LZTS1 promoted cell proliferation and tumor growth in CRC cells. Furthermore, we demonstrated that LZTS1 inhibited cell proliferation and tumor growth in CRC in part via suppression of AMT-mTOR, subsequently down-regulating p27Kip and up-regulating cyclin D1. These findings suggest that LZTS1 plays a potential tumor suppressor role in CRC progression and represents a valuable clinical prognostic marker of this disease.

miR-450b-5p induced by oncogenic KRAS is required for colorectal cancer progression

The development and progression of CRC are regarded as a complicated network and progressive event including genetic and/or epigenetic alterations. Recent researches revealed that MicroRNAs are biomarkers and regulators of CRC progression. Analyses of published microarray datasets revealed that miR-450b-5p was highly up-regulated in CRC tissues. In addition, high expression of miR-450b-5p was significantly associated with KRAS mutation. However, the role of miR-450b-5p in the progression of CRC remains unknown. Here, we sought to validate the expression of miR-450b-5p in CRC tissues and investigate the role and underlying mechanism of miR-450b-5p in the progression of CRC. The results revealed that miR-450b-5p was up-regulated in CRC tissues, high expression level of miR-450b-5p was positively associated with poor differentiation, advanced TNM classification and poor prognosis. Moreover, miR-450b-5p was especially high in KRAS-mutated cell lines and could be up-regulated by KRAS/AP-1 signaling. Functional validation revealed that overexpression of miR-450b-5p promoted cell proliferation and tumor growth while inhibited apoptosis of CRC cells. Furthermore, we demonstrated that miR-450b-5p directly bound the 3′-UTRs of SFRP2 and SIAH1, and activated Wnt/β-Catenin signaling. In conclusion, miR-450b-5p induced by oncogenic KRAS is required for colorectal cancer progression. Collectively, our work helped to understand the precise role of miR-450b-5p in the progression of CRC, and might promote the development of new therapeutic strategies against CRC.

STX2 promotes colorectal cancer metastasis through a positive feedback loop that activates the NF-κB pathway

Metastatic progression is the main contributor to the poor prognosis of colorectal cancer (CRC). Thus, identifying the determinants of CRC metastasis will be of great significance. Based on our previous bioinformatics analysis, Syntaxin2 (STX2) may be upregulated and correlated with the poor prognosis of CRC patients. In this study, we found that STX2 expression was associated with CRC invasion and metastasis and poor patient survival. Gain- and loss-of-function analyses demonstrated that STX2 functioned as a key oncogene by promoting CRC invasion and metastasis. Mechanistically, STX2 selectively interacted with tumor necrosis factor receptor-associated factor 6 (TRAF6) and activated the nuclear transcription factor-κB (NF-κB) signaling pathway. Furthermore, chromatin immunoprecipitation (ChIP) analysis revealed that NF-κB directly bound to the STX2 promoter and drove STX2 transcription. Therefore, STX2 activated the NF-κB pathway, and in turn, NF-κB increased STX2 expression, forming a positive signaling loop that eventually promoted CRC metastasis. Collectively, our results reveal STX2 as a crucial modulator of the aggressive CRC phenotype and highlight STX2 as a potential prognostic biomarker and therapeutic target for combating CRC metastasis.