The FAK inhibitor BI 853520 inhibits spheroid formation and orthotopic tumor growth in malignant pleural mesothelioma

Viktoria Laszlo,Michael Grusch,Balazs Dome,Judit Ozsvar,Jozsef Tovari,Balazs Hegedus,Walter Klepetko,Zsuzsanna Valko,Irene C Waizenegger,Marion Gröger,Thomas Klikovits,Mir Alireza Hoda,Walter Berger,Tamas Garay,Ildiko Kovacs,Clemens Aigner,Paul Stockhammer

doi:10.1007/s00109-018-1725-7

Abstract

No tyrosine kinase inhibitors are approved for malignant pleural mesothelioma (MPM). Preclinical studies identified focal adhesion kinase (FAK) as a target in MPM. Accordingly, we assessed the novel, highly selective FAK inhibitor (BI 853520) in 2D and 3D cultures and in vivo. IC50 values were measured by adherent cell viability assay. Cell migration and 3D growth were quantified by video microscopy and spheroid formation, respectively. Phosphorylation of FAK, Akt, S6, and Erk was measured by immunoblot. The mRNA expression of the putative tumor stem cell markers SOX2, Nanog, CD44, ALDH1, c-myc, and Oct4 was analyzed by qPCR. Cell proliferation, apoptosis, and tumor tissue microvessel density (MVD) were investigated in orthotopic MPM xenografts. In all 12 MPM cell lines, IC50 exceeded 5 μM and loss of NF2 did not correlate with sensitivity. No synergism was found with cisplatin in adherent cells. BI 853520 decreased migration in 3 out of 4 cell lines. FAK phosphorylation was reduced upon treatment but activation of Erk, Akt, or S6 remained unaffected. Nevertheless, BI 853520 inhibited spheroid growth and significantly reduced tumor weight, cell proliferation, and MVD in vivo. BI 853520 has limited effect in adherent cultures but demonstrates potent activity in spheroids and in orthotopic tumors in vivo. Based on our findings, further studies are warranted to explore the clinical utility of BI 853520 in human MPM.Key messagesResponse to FAK inhibition in MPM is independent of NF2 expression or histotype.FAK inhibition strongly interfered with MPM spheroid formation.BI 853520 has been shown to exert anti-tumor effect in MPM.

Highlights

Malignant pleural mesothelioma (MPM) is a highly aggressive malignancy with a strong link to prior asbestos exposure
In order to investigate whether histological subtype and merlin or E-cadherin expression influence the sensitivity of MPM cells to Focal adhesion kinase (FAK) inhibition in vitro, we determined the IC50 values by performing sulforhodamine B (SRB) assays of adherently grown cells following 72 h of BI 853520 treatment (Fig. 1 and Table 1)
In our panel of cell lines, Since certain FAK inhibitors demonstrated a synergistic effect with cisplatin in other malignant diseases [9], cell viability was measured when BI 853520 was applied in combination with cisplatin

Summary

Introduction

Malignant pleural mesothelioma (MPM) is a highly aggressive malignancy with a strong link to prior asbestos exposure. FAK overexpression has been preferentially linked to a more aggressive tumor behavior, by promoting tumor cell proliferation, survival, motility, invasion, stem cell renewal, angiogenesis, and metastasis [4, 6, 7, 9,10,11]. In this context, there is emerging evidence for a functional role of FAK gene amplification and protein overexpression during tumor progression in different tumor types including lung, breast, colorectal, thyroid, kidney, and pancreatic cancers as well as astrocytoma and osteosarcoma [10, 12,13,14]. Recent studies demonstrated that FAK activation is an important regulator of the immunosuppressive tumor microenvironment and promotes immune evasion in murine models of squamous cell carcinoma and pancreatic cancer [15, 16]

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Results

Conclusion