High miR-196a levels promote the oncogenic phenotype of colorectal cancer cells

AIM: To analyze the relevance of the microRNA miR-196a for colorectal oncogenesis. METHODS: The impact of miR-196a on the restriction targets HoxA7, HoxB8, HoxC8 and HoxD8 was analyzed by reverse transcription polymerase chain reaction (RT-PCR) after transient transfection of SW480 cancer cells. The miR-196a transcription profile in colorectal cancer samples, mucosa samples and diverse cancer cell lines was quantifi ed by RT-PCR. Transiently miR-196a-transfected colorectal cancer cells were used for diverse functional assays in vitro and for a xenograft lung metastasis model in vivo. RESULTS: HoxA7, HoxB8, HoxC8 and HoxD8 were restricted by miR-196a in a dose-dependent and gene-specific manner. High levels of miR-196a activated the AKT signaling pathway as indicated by increased phosphorylation of AKT. In addition, high levels of miR-196a promoted cancer cell detachment,migration, invasion and chemosensitivity towards platin derivatives but did not impact on proliferation or apoptosis. Furthermore, miR-196a increased the development of lung metastases in mice after tail vein injection. CONCLUSION: miR-196a exerts a pro-oncogenic influence in colorectal cancer.

Coexpression of receptor-tyrosine-kinases in gastric adenocarcinoma-a rationale for a molecular targeting strategy?

AIM: To define the (co-)expression pattern of target receptor-tyrosine-kinases (RTK) in human gastric adenocarcinoma. METHODS: The (co-)expression pattern of VEGFR1-3,PDGFRα/b and EGFR1 was analyzed by RT-PCR in 51 human gastric adenocarcinomas. In addition,IHC staining was applied for confirmation of expression and analysis of RTK localisation. RESULTS: The majority of samples revealed a VEGFR1 (98%),VEGFR2 (80%),VEGFR3 (67%),PDGFRα (82%) and PDGFRβ(82%) expression,whereas only 62% exhibited an EGFR1 expression. 78% of cancers expressed at least four out of six RTKs. While VEGFR1-3 and PDGFRα revealed a predominantly cytoplasmatic staining in tumor cells,accompanied by an additional nuclear staining for VEGFR3 ,EGFR1 was almost exclusively detected on the membrane of tumor cells. PDGFRβ was restricted to stromal pericytes,which also depicted a PDGFRα expression.receptor-tyrosine-kinases coexpression in gastric adenocarcinoma and might therefore encourage an application of multiple-target RTK-inhibitors within a combination therapy.