A chimeric protein PTEN-L-p53 enters U251 cells to repress proliferation and invasion

• Published in: Experimental cell research 2018-08, Vol.369 (2), p.234-242
• Main Authors: Xiao, Man, An, Yang, Wang, Fengling, Yao, Chao, Zhang, Chu, Xin, Junfang, Duan, Yongjian, Zhao, Xiaofang, Fang, Na, Ji, Shaoping
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; AMINO ACIDS; Cancer; CYTOPLASM; DNA; NEOPLASMS; PEPTIDES; PTEN-L-p53; PTEN-Long; RNA; TP53; U251 cells
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/j.yexcr.2018.05.023

PTEN, a well-known tumor suppressor, dephosphorylates PIP3 and inhibits AKT activity. A translational variant of PTEN has been identified and termed PTEN-Long (PTEN-L). The additional 173 amino acids (PTEN-L leader) at the N-terminal constitute a potential signal peptide. Differing from canonical PTEN, PTEN-L is secreted into the extracellular fluid and re-enters recipient cells, playing the similar roles as PTEN in vivo and in vitro. This character confers the PTEN-L a therapeutic ability via directly protein delivering instead of traditional DNA and RNA vector options. In the present study, we employed PTEN-L leader to assemble a fusion protein, PTEN-L-p53, inosculated with the transcriptional regulator TP53, which is another powerful tumor suppressor. We overexpressed PTEN-L-p53 in HEK293T cells and detected it in both the cytoplasm and nucleus. Subsequently, we found that PTEN-L-p53 was secreted outside of the cells and detected in the culture media by immunoblotting. Furthermore, we demonstrated that PTEN-L-p53 freely entered the cells and suppressed the viability of U251cells (p53R273H, a cell line with p53 R273H-mutation). PTEN-L-p53 is composed of endogenous protein/peptide bearing low immunogenicity, and only the junction region between PTEN-L leader and p53 can act as a new immune epitope. Accordingly, this fusion protein can potentially be used as a therapeutic option for TP53-abnormality cancers. •PTEN-L leader drives p53 re-entry to U251 cells.•PTEN-L-p53 permeates the membrane barriers to locate in the both cellular cytoplasm and nucleus.•PTEN-L-p53 represses the proliferation, migration and invasion of U251 cells.