Enhanced efficacy of AKT and FAK kinase combined inhibition in squamous cell lung carcinomas with stable reduction in PTEN

Abstract

// Andrea Cavazzoni 1 , Silvia La Monica 1 , Roberta Alfieri 1 , Andrea Ravelli 1 , Nele Van Der Steen 2 , Rocco Sciarrillo 2 , Denise Madeddu 1 , Costanza Anna Maria Lagrasta 1 , Federico Quaini 1 , Mara Bonelli 1 , Claudia Fumarola 1 , Daniele Cretella 1 , Graziana Digiacomo 1 , Marcello Tiseo 3 , Godefridus J. Peters 2 , Andrea Ardizzoni 4 , Pier Giorgio Petronini 1, * and Elisa Giovannetti 2, 5, * 1 Department of Medicine and Surgery, University of Parma, Parma, Italy 2 Department of Medical Oncology, VU University Medical Center Amsterdam, Amsterdam, The Netherlands 3 Medical Oncology Unit, University Hospital of Parma, Parma, Italy 4 Division of Medical Oncology, Sant'Orsola-Malpighi University Hospital, Bologna, Italy 5 Cancer Pharmacology Lab, AIRC/Start-Up Unit, University of Pisa, Pisa, Italy * Joint last authors Correspondence to: Andrea Cavazzoni, email: andrea.cavazzoni@unipr.it Roberta Alfieri, email: roberta.alfieri@unipr.it Keywords: PTEN, FAK, PI3K, target therapy, squamous lung carcinoma Received: November 25, 2016      Accepted: May 12, 2017      Published: May 23, 2017 ABSTRACT Squamous cell lung carcinoma (SCC) accounts for 30% of patients with NSCLC and to date, no molecular targeted agents are approved for this type of tumor. However, recent studies have revealed several oncogenic mutations in SCC patients, including an alteration of the PI3K/AKT pathway, i.e. PI3K point mutations and amplification, AKT mutations and loss or reduced PTEN expression. Prompted by our observation of a correlation between PTEN loss and FAK phosphorylation in a cohort of patients with stage IV SCC, we evaluated the relevance of PTEN loss in cancer progression as well as the efficacy of a new combined treatment with the pan PI3K inhibitor buparlisip and the FAK inhibitor defactinib. An increase in AKT and FAK phosphorylation, associated with increased proliferation and invasiveness, paralleled by the acquisition of mesenchymal markers, and overexpression of the oncomir miR-21 were observed in SKMES-1-derived cell clones with a stable reduction of PTEN. Notably, the combined treatment induced a synergistic inhibition of cell proliferation, and a significant reduction in cell migration and invasion only in cells with reduced PTEN. The molecular mechanisms underlying these findings were unraveled using a specific RTK array that showed a reduction in phosphorylation of key kinases such as JNK, GSK-3 α/β, and AMPK-α2, due to the concomitant decrease in AKT and FAK activation. In conclusion, the combination of buparlisib and defactinib was effective against cells with reduced PTEN and warrants further studies as a novel therapeutic strategy for stage IV SCC patients with loss of PTEN expression.