EPHA2 mutations with oncogenic characteristics in squamous cell lung cancer and malignant pleural mesothelioma

Our plain-English summary of EPHA2 mutations with oncogenic characteristics in squamous cell lung cancer and malignant pleural mesothelioma, by Y.C. Tan, S. Srivastava, B.M. Won, et al (Oncogenesis, 2019).

The study

• Authors: Y.C. Tan, S. Srivastava, B.M. Won, R. Kanteti, Q. Arif, A.N. Husain, H. Li, W.T. Vigneswaran, K.M. Pang, P. Kulkarni, M. Sattler, N. Vaidehi, I. Mambetsariev, H.L. Kindler, D.L. Wheeler, R. Salgia
• Journal: Oncogenesis
• Published: 2019;8(9):49
• Cited by: 24 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Squamous cell carcinoma (SCC) and malignant pleural mesothelioma (MPM) are thoracic malignancies with very poor prognosis and limited treatment options. It is an established fact that most of the solid tumors have overexpression of EPHA2 receptor tyrosine kinase. EPHA2 is known to exhibit opposing roles towards cancer progression. It functions in inhibiting cancer survival and migration via a ligand and tyrosine kinase dependent signaling (Y772). Whereas it is known to promote tumor progression and cell migration through a ligand-independent signaling (S897). We analyzed the expression profile and mutational status of the ephrin receptor A2 (EPHA2) in SCC and MPM cell lines and primary patient specimens. The EPHA2 receptor was found to be either overexpressed, mutated or amplified in SCC and MPM. In particular, the EPHA2 mutants A859D and T647M were interesting to explore, A859D Y772 dead mutant exhibited lower levels of phosphorylation at Y772 compared to T647M mutant. Molecular Dynamics simulations studies suggested that differential changes in conformation might form the structural basis for differences in the level of EPHA2 activation. Consequently, A859D mutant cells exhibited increased proliferation as well as cell migration compared to controls and T647M mutant. Kinomics analysis demonstrated that the STAT3 and PDGF pathways were upregulated whereas signaling through CBL was suppressed. Considered together, the present work has uncovered the oncogenic characteristics of EPHA2 mutations in SSC and MPM reinstating the dynamics of different roles of EPHA2 in cancer. This study also suggests that a combination of doxazosin and other EPHA2 inhibitors directed to inhibit the pertinent signaling components may be a novel therapeutic strategy for MPM and Non-small cell lung cancer patients who have either EPHA2 or CBL alterations.

In plain English

This laboratory study examined the EPHA2 receptor gene and protein in lung squamous cell carcinoma (SCC) and malignant pleural mesothelioma (MPM). The authors analysed DNA from 35 SCC and 39 MPM patient tumours and six MPM cell lines for mutations and amplification, measured EPHA2 protein, and studied engineered mutant cells. EPHA2 mutations were found in 28% (11/39) of MPM samples. For SCC, the Results text reported only the mutant R876H, but a figure caption listed novel SCC mutations R159G and R876C, so the article is inconsistent on this point. Amplification was found in about 10% (4/39) of MPM tumours and 33% (2/6) of MPM cell lines. EPHA2 was overexpressed in 4 of 6 MPM cell lines, and overall immunohistochemistry scores were 2.74 for 65 MPM tumours versus 2.06 for nine normal samples. In engineered HEK293 cells, the A859D and T647M mutants proliferated more than wild-type cells, and A859D also migrated more and resisted doxazosin. Computer simulations suggested a structural basis for reduced Y772 phosphorylation in A859D. Asbestos exposure was among the clinical information collected for the samples, but the article reported no analysis of it.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory study of patient tumour specimens, cell lines and engineered mutant cells, with kinome profiling and molecular dynamics computer simulations
• Who was studied: 35 squamous cell carcinoma and 39 malignant pleural mesothelioma patient tumours plus six MPM cell lines for DNA analysis; tissue microarrays of 65 MPM tumours with nine normal mesothelium samples and 48 SCC tumours with adjacent normal tissue; archival samples from the University of Chicago
• Exposure: Not an environmental exposure study: the variables studied were EPHA2 alterations (including mutations A859D, T647M and G391R) introduced into cells, and drug treatments with cisplatin, taxol, rapamycin, SU11274 and doxazosin. Asbestos exposure was recorded among clinical information for the samples, but no analysis of it is reported.
• Main results:
  • EPHA2 mutations were detected in 28% (11/39) of MPM patient samples. The Results text states that in SCC only the mutant R876H was observed.
  • The Figure 2 caption, by contrast, lists novel mutations R159G and R876C and several known SNPs, including R876H, in SCC tumour tissue. This conflicts with the Results text.
  • EPHA2 gene amplification was found in about 10% (4/39) of MPM patient samples and 33% (2/6) of MPM cell lines
  • EPHA2 protein was overexpressed in 4 of 6 MPM cell lines compared with the normal mesothelial cell line Met-5A
  • Overall immunohistochemistry scores were 2.74 in 65 MPM tumours versus 2.06 in nine normal mesothelium samples. In SCC the scores were 1.74 for tumour and 0.5 for adjacent normal tissue.
  • In HEK293 isogenic cells, the A859D and T647M mutants proliferated more than wild-type EPHA2 cells. A859D cells also migrated more than T647M and control cells at 2 and 5 hours.
  • MPM cell lines overexpressing EPHA2 (H513, H2052, H2596) were sensitive to cisplatin, while low-EPHA2 lines (H28, H2461) were resistant. HEK293 A859D mutant cells were resistant to doxazosin.
  • Kinomics pathway analysis identified Tec kinase signaling, STAT3, axonal guidance, T cell receptor and PDGF signaling as the top canonical pathways (p less than 0.001)
  • In the molecular dynamics simulations, the A859D mutant did not bring Y772 close to K702, which could impair Y772 phosphorylation compared with wild-type
• The authors' conclusion: The authors concluded that they had uncovered oncogenic versus tumour suppressor characteristics of EPHA2 and its mutations in SCC and MPM. They suggested that combining doxazosin with other EPHA2 inhibitors may be a therapeutic strategy for MPM and NSCLC patients with EPHA2 or CBL alterations.

Topics

Medical terms in this study, explained in our Lexicon: Squamous Cell Carcinoma, Lung Cancer, Pleural Mesothelioma, Prognosis, Platelet-Derived Growth Factor (PDGF), Non-Small Cell Lung Cancer.

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