Lipid and protein tumor markers for head and neck squamous cell carcinoma identified by imaging mass spectrometry.

Janos Schmidt,Béla Kajtár,Mária Péter,László Kereskai,Lászó Márk,Tamás Tornóczki,Gábor Balogh,Kata Juhász,Zsolt Balogi,Imre Gerlinger,László Vígh,András Burián,Tamás Járai

doi:10.18632/oncotarget.27649

Abstract

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. To improve pre- and post-operative diagnosis and prognosis novel molecular markers are desirable. Here we used MALDI imaging mass spectrometry (IMS) and immunohistochemistry (IHC) to seek tumor specific expression of proteins and lipids in HNSCC samples. Among low molecular weight proteins visualized, S100A8 and S100A9 were found to be expressed in the regions of tumor tissue but not in the surrounding healthy stroma of a post-operative microdissected tissue. Marker potential of S100A8 and S100A9 was confirmed by immunohistochemistry of paraffin-embedded pathological samples. Imaging lipids showed a remarkable depletion of lysophosphatidylcholine species LPC[16:0], LPC[18:2] and, in parallel, accumulation of major glycerophospholipid species PE-P[36:4], PC[32:1], PC[34:1] in neoplastic areas. This was confirmed by shotgun lipidomics of dissected healthy and tumor tissue sections. A combination of the negative (LPC[16:0]) and positive (PC[32:1], PC[34:1]) markers was also applicable to uncover tumorous character of a pre-operative biopsy. Furthermore, marker potential of lysophospholipids was supported by elevated expression levels of the lysophospholipid degrading enzyme lysophospholipase A1 (LYPLA1) in the tumor regions of paraffin-embedded HNSCC samples. Finally, experimental evidence of 3D cell spheroid tests showed that LPC[16:0] facilitates HNSCC invasion, implying that HNSCC progression in vivo may be dependent on lysophospholipid supply. Altogether, a series of novel proteins and lipid species were identified by IMS and IHC screening, which may serve as potential molecular markers for tumor diagnosis, prognosis, and may pave the way to better understand HNSCC pathophyisiology.

Highlights

IntroductionHead and neck squamous cell carcinoma (HNSCC) includes a family of tumors arising from multiple locations (mouth, throat, larynx, sinuses and salivary glands) and is currently the sixth most common cancer worldwide
Head and neck squamous cell carcinoma (HNSCC) includes a family of tumors arising from multiple locations and is currently the sixth most common cancer worldwide
Large enough to explore potential intratumoral heterogeneity, this HNSCC specimen was chosen for in-depth screening (Figure 1). 15 μm cryosections were prepared for pathological hematoxylin-eosin (H/E) staining and MALDI imaging mass spectrometry (IMS) (Figure 1), and the remaining tissue was kept frozen for further analysis

Summary

Introduction

Head and neck squamous cell carcinoma (HNSCC) includes a family of tumors arising from multiple locations (mouth, throat, larynx, sinuses and salivary glands) and is currently the sixth most common cancer worldwide. Human papillomavirus (HPV) or Epstein–Barr virus infections are associated with subgroups of HNSCCs. Despite complex treatment modalities (surgery, radiation, chemo-, photodynamic or targeted therapies) overall survival rates have only marginally increased for a long time. Improving treatment success rates would require earlier and more precise diagnosis as well as clinically applicable specific molecular markers of the tumor with prognostic value [1]. Molecular marker candidates of HNSCC include HPV, EGFR mutations, chemokine receptors, methylation markers, interleukins, which are mostly related to a subgroup of cases and fail to provide a basis for specific and sensitive tumor identification [2]. Seeking molecular markers for early and precise diagnosis, reliable prediction of treatment results and recurrence rate remains a major goal in fighting HNSCC

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