Nuclear B-catenin forms a transcription complex with TCF-4, which is implicated in colon cancer development and progression. Recently, we and others have shown that B-catenin could be a regulator of RNA splicing and it also stabilizes the cyclooxygenase-2 (COX-2) mRNA. Here, we further explored the role of B-catenin in the RNA metabolism in colon cancer cells. To specifically modulate the subcellular functions of B-catenin, we expressed the RNA aptamer in the form of RNA intramers with unique cellular localizations. The nucleus-expressed RNA intramer proved to be effective in reducing the protein-protein interaction between B-catenin and TCF-4, thus shown to be a specific regulator of B-cateninactivated transcription. It could also regulate the alternative splicing of E1A minigene in diverse colon cancer cell lines. In addition, we tested whether B-catenin could stabilize any other mRNAs and found that cyclin D1 mRNA was also bound and stabilized by B-catenin. Significantly, the cytoplasmexpressed RNA intramer reverted the B-catenin-induced COX-2 and cyclin D1 mRNA stabilization. We show here that B-catenin regulated multiple steps of RNA metabolism in colon cancer cells and might be the protein factor coordinating RNA metabolism. We suggest that the RNA intramers could provide useful ways for inhibiting B-catenin-mediated transcription and RNA metabolism, which might further enhance the antitumorigenic effects of these molecules in colon cancer cells. [Cancer Res 2007;67(19):9315-21]

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Hamstring injuries are common forms of muscle strains in athletes but a complete rupture of a proximal hamstring origin is rare. Often there is a considerable delay in diagnosis and stringent treatment because of its rarity, difficulty in clinical diagnosis, and initial attempts of conservative care. We report two cases of acute complete rupture of the proximal hamstring tendons treated with early surgical repair. The diagnosis and treatment of this unusual injury are discussed.

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