TAM family receptors in conjunction with MAPK signalling are involved in acquired resistance to PI3Kα inhibition in head and neck squamous cell carcinoma

Abstract

Background Aberrant activation of the phosphatidylinositol 3-kinase (PI3K) pathway is common in many malignancies, including head and neck squamous cell carcinoma (HNSCC). Despite pre-clinical and clinical studies, outcomes from targeting the PI3K pathway have been underwhelming and the development of drug resistance poses a significant barrier to patient treatment. In the present study, we examined mechanisms of acquired resistance to the PI3Kα inhibitor alpelisib (formerly BYL719) in HNSCC cell lines and patient-derived xenografts (PDXs). Methods Five unique PDX mouse models and three HNSCC cell lines were used. All cell lines and xenografts underwent genomic characterization prior to study. Serial drug treatment was conducted in vitro and in vivo to develop multiple, clinically-significant models of resistance to alpelisib. We then used reverse phase protein arrays (RPPAs) to profile the expression of proteins in parental and drug-resistant models. Top hits were validated by immunoblotting and immunohistochemistry. Flow cytometric analysis and RNA interference studies were then used to interrogate the molecular mechanisms underlying acquired drug resistance. Results Prolonged treatment with alpelisib led to upregulation of TAM family receptor tyrosine kinases TYRO3 and AXL. Importantly, a significant shift in expression of both TYRO3 and AXL to the cell surface was detected in drug-resistant cells. Targeted knockdown of TYRO3 and AXL effectively re-sensitized resistant cells to PI3Kα inhibition. In vivo, resistance to alpelisib emerged following 20–35 days of treatment in all five PDX models. Elevated TYRO3 expression was detected in drug-resistant PDX tissues. Downstream of TYRO3 and AXL, we identified activation of intracellular MAPK signalling. Inhibition of MAPK signalling also re-sensitized drug-resistant cells to alpelisib. Conclusions We have identified TYRO3 and AXL receptors to be key mediators of resistance to alpelisib, both in vitro and in vivo. Our findings suggest that pan-TAM inhibition is a promising avenue for combinatorial or second-line therapy alongside PI3Kα inhibition. These findings advance our understanding of the role TAM receptors play in modulating the response of HNSCC to PI3Kα inhibition and suggest a means to prevent, or at least delay, resistance to PI3Kα inhibition in order to improve outcomes for HNSCC patients.

IGF2 Mediates Resistance to Isoform-Selective-Inhibitors of the PI3K in HPV Positive Head and Neck Cancer

“…In summary, our findings highlight the likelihood that the factors governing the acquisition of resistance in HNC HPV+ may be distinct from those in HNC HPV− . While, in HNC HPV− , expression of RTKs increases following PI3K treatment [ 20 , 58 , 59 , 60 , 61 ], in HNC HPV+ , tumor cells acquire resistance to isiPI3K by the secretion of IGF2 to activate IGF1R. Our results provide the first evidence that blocking the IGF2/IGF1R pathway in combination with isiPI3K is a promising therapeutic strategy for treating HNC HPV+ patients.…”

“…Different molecular paths can lead to isiPI3K resistance, including sustained activation of mTORC1 [ 21 , 54 , 55 ], PDK1/SGK1 [ 56 ], and MYC [ 57 ]. In HNC HPV− , acquisition of resistance to isiPI3K is driven by increased activity of receptor tyrosine kinases (RTK), like EGFR [ 20 , 58 ], AXL [ 20 , 59 , 60 ], and HER3 [ 61 ], which signal through AKT or RAS/ERK pathways, or by activation of RTKs downstream of ERK/TSC2 [ 61 ], p85 [ 62 ], and CDK4/6 [ 63 ]. While, in HNC HPV− , different mechanisms of resistance to isiPI3K have been well documented by us and by others, in HNC HPV+ , only innate resistance to isiPI3K has been reported [ 64 ].…”

G-749 Promotes Receptor Tyrosine Kinase TYRO3 Degradation and Induces Apoptosis in Both Colon Cancer Cell Lines and Xenograft Mouse Models

“…According to recent studies, the TAM RTK family plays an important role in various cancers ( Post et al, 2021 ). Among them, AXL and MER are known proto-oncogenes and have been confirmed to be overexpressed in several cancer types ( Rothlin et al, 2014 ; Morimoto et al, 2020 ; Ruicci et al, 2020 ). While AXL and MER have been thoroughly investigated, the role of TYRO3 in cancer development remains unknown.…”

“…Down-regulation of TYRO3 via RNAi in breast, colon, head and neck and pancreatic cancers has been reported to regulate the cellular signaling pathway by reducing the phosphorylation of STAT3, AKT, and ERK. Conversely, the overexpression of TYRO3 has been shown to increase the phosphorylation of ERK and AKT ( Lan et al, 2000 ; Ekyalongo et al, 2014 ; Duan et al, 2016 ; Qin and QIAN, 2018 ; Morimoto et al, 2020 ; Ruicci et al, 2020 ; Tsai et al, 2020 ). AKT and ERK are key mediators in regulating the survival and proliferation of cancer cells ( Herrero et al, 2015 ; Song et al, 2019 ), whereas STAT3 is a transcription factor involved in cell survival and apoptosis ( Xiong et al, 2008 ; Lee et al, 2019 ).…”

Therapeutic implications of activating noncanonical PIK3CA mutations in head and neck squamous cell carcinoma

“…They also reported that persistent activation of mTOR signaling in HNSCC cell lines bearing either mutated (H1047R) or amplified PIK3CA confers resistance to alpelisib, and that the activation is mediated via AXL interaction with EGFR (57,58). Another study reported that acquired resistance to alpelisib in a PIK3CA-mutant (H1047R) HNSCC cell line was associated with increased expression of the TAM family receptors TYRO3 and AXL (59). Therefore, as with many other targeted therapies, dissecting the underlying mechanisms driving resistance may lead to improved treatment approaches.…”