A novel RON splice variant lacking exon 2 activates the PI3K/AKT pathway via PTEN phosphorylation in colorectal carcinoma cells
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Yu Ling1,*, Yeye Kuang2,*, Lin-Lin Chen1, Wei-Feng Lao1, Yao-Ru Zhu1, Le-Qi Wang1 and Da Wang1
1Department of Colorectal Surgery, Sir Run Run Shaw Hospital, Zhejiang University of Medicine, Hangzhou, Zhejiang 310016, People’s Republic of China
2Biomedical Center, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310016, People’s Republic of China
*These authors have contributed equally to this work
Da Wang, email: [email protected]
Keywords: RON, splicing variants, PTEN, PI3K/AKT pathway, colorectal cancer cell
Received: January 06, 2017 Accepted: March 01, 2017 Published: March 27, 2017
Abnormal expression of the Recepteur d’Origine Nantais (RON) receptor tyrosine kinase is accompanied by the generation of multiple splice or truncated variants, which mediate many critical cellular functions that contribute to tumor progression and metastasis. Here, we report a new RON splice variant in the human colorectal cancer (CRC) cell line HT29. This variant is a 165 kda protein generated by alternative pre-mRNA splicing that eliminates exon 2, causing an in-frame deletion of 63 amino acids in the extracellular domain of the RON β chain. The deleted transcript was a single chain expressed in the intracellular compartment. Although it lacked tyrosine phosphorylation activity, the RONΔ165E2 variant could phosphorylate phosphatase and tensin homolog (PTEN), thereby activating the PI3K/AKT pathway. In addition, in vitro and in vivo experiments showed that the RONΔ165E2 promoted cell migration and tumor growth. Finally, in an investigation of 67 clinical CRC samples, the variant was highly expressed in about 58% of the samples, and was positively correlated with the invasive depth of the tumor (P < 0.05). These results demonstrate that the novel RONΔ165E2 variant promoted tumor progression while activating the PI3K/AKT pathway via PTEN phosphorylation.
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