Sharpin promotes hepatocellular carcinoma progression via transactivation of versican expression

Sharpin (Shank-associated RH domain-interacting protein, also known as SIPL1) is a multifunctional molecule that participates in various biological settings, including nuclear factor-B signaling activation and tumor suppressor gene inhibition. Sharpin is upregulated in various types of cancers, including hepatocellular carcinoma (HCC), and is implicated in tumor progression. However, the exact roles of Sharpin in tumorigenesis and tumor progression remain largely unknown. Here, we report novel mechanisms of HCC progression through Sharpin overexpression. Sharpin was upregulated in human HCC tissues. Increased Sharpin expression enhanced hepatoma cell invasion, whereas decrease in Sharpin expression by RNA interference inhibited invasion. Microarray analysis identified that versican, a chondroitin sulfate proteoglycan that plays crucial roles in tumor progression and invasion, was also upregulated in stably Sharpin-expressing cells. Versican expression increased in the majority of HCC tissues and knocking down of versican greatly attenuated hepatoma cell invasion. Sharpin expression resulted in a significant induction of versican transcription synergistically with Wnt/-catenin pathway activation. Furthermore, Sharpin overexpressing cells had high tumorigenic properties in vivo. These results demonstrate that Sharpin promotes versican expression synergistically with the Wnt/-catenin pathway, potentially contributing to HCC development. A Sharpin/versican axis could be an attractive therapeutic target for this currently untreatable cancer.

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Tanaka Y, Tateishi K, Nakatsuka T, Kudo Y, Takahashi R, Miyabayashi K, Yamamoto K, Asaoka Y, Ijichi H, Tateishi R, Shibahara J, Fukayama M, Ishizawa T, Hasegawa K, Kokudo N, Koike K