LZTS2 inhibits PI3K/AKT activation and radioresistance in nasopharyngeal carcinoma by interacting with p85

Phosphoinositide 3-kinase (PI3K) activity is aberrantly activated in nasopharyngeal carcinoma. However, the underlying mechanisms remain unclear. Here, we found that Leucine zipper tumor suppressor 2 (LZTS2) was downregulated and predicted poor prognosis in nasopharyngeal carcinoma patients. Furthermore, we identified the PI3K subunit p85 as a novel LZTS2-interacting protein using an unbiased proteomics approach. Moreover, we demonstrated that LZTS2 competes with p110 for p85 binding and inhibits activation of the PI3K/AKT signaling pathway. Functionally, we showed that LZTS2 suppresses tumorigenesis and radioresistance in nasopharyngeal carcinoma in a p85-dependent manner. Taken together, our results not only provide understanding of the molecular mechanisms by which PI3K/AKT signaling is activated but also suggest that targeting the LZTS2/PI3K/AKT signaling axis is a promising therapeutic strategy for radiosensitization of nasopharyngeal carcinoma. (C) 2018 Elsevier B.V. All rights reserved.