Protein Kinase C Isozymes Associated With Relapse Free Survival in Non-Small Cell Lung Cancer Patients

Ann Rita Halvorsen; Mads Haugland Haugen; Åsa Kristina Öjlert; Marius Lund-Iversen; Lars Jørgensen; Steinar Solberg; Gunhild M Mælandsmo; Odd Terje Brustugun; Åslaug Helland

doi:10.3389/fonc.2020.590755

Protein Kinase C Isozymes Associated With Relapse Free Survival in Non-Small Cell Lung Cancer Patients

Front Oncol. 2020 Nov 25:10:590755. doi: 10.3389/fonc.2020.590755. eCollection 2020.

Authors

Ann Rita Halvorsen^{1

2}, Mads Haugland Haugen³, Åsa Kristina Öjlert¹, Marius Lund-Iversen⁴, Lars Jørgensen⁵, Steinar Solberg⁵, Gunhild M Mælandsmo^{3

6}, Odd Terje Brustugun^{1

7}, Åslaug Helland^{1

2

8}

Affiliations

¹ Department of Cancer Genetics, Institute for Cancer Research, Oslo University Hospital-Radiumhospitalet, Oslo, Norway.
² Department of Clinical Medicine, University of Oslo, Oslo, Norway.
³ Department of Tumor Biology, Institute for Cancer Research, Oslo University Hospital-Radiumhospitalet, Oslo, Norway.
⁴ Department of Pathology, Oslo University Hospital-Radiumhospitalet, Oslo, Norway.
⁵ Department of Cardiothoracic Surgery, Oslo University Hospital-Rikshospitalet, Oslo, Norway.
⁶ Faculty of Health Sciences, Institute of Medical Biology, UiT-Arctic University of Norway, Tromso, Norway.
⁷ Section of Oncology, Drammen Hospital, Vestre Viken Hospital Trust, Drammen, Norway.
⁸ Department of Oncology, Oslo University Hospital-Radiumhospitalet, Oslo, Norway.

Abstract

Introduction: Protein expression is deregulated in cancer, and the proteomic changes observed in lung cancer may be a consequence of mutations in essential genes. The purpose of this study was to identify protein expression associated with prognosis in lung cancers stratified by smoking status, molecular subtypes, and EGFR-, TP53-, and KRAS-mutations.

Methods: We performed profiling of 295 cancer-relevant phosphorylated and non-phosphorylated proteins, using reverse phase protein arrays. Biopsies from 80 patients with operable lung adenocarcinomas were analyzed for protein expression and association with relapse free survival (RFS) were studied.

Results: Spearman's rank correlation analysis identified 46 proteins with significant association to RFS (p<0.05). High expression of protein kinase C (PKC)-α and the phosporylated state of PKC-α, PKC-β, and PKC-δ, showed the strongest positive correlation to RFS, especially in the wild type samples. This was confirmed in gene expression data from 172 samples. Based on protein expression, unsupervised hierarchical clustering separated the samples into four subclusters enriched with the molecular subtypes terminal respiratory unit (TRU), proximal proliferative (PP), and proximal inflammatory (PI) (p=0.0001). Subcluster 2 contained a smaller cluster (2a) enriched with samples of the subtype PP, low expression of the PKC isozymes, and associated with poor RFS (p=0.003) compared to the other samples. Low expression of the PKC isozymes in the subtype PP and a reduced relapse free survival was confirmed with The Cancer Genome Atlas (TCGA) lung adenocarcinoma (LUAD) samples.

Conclusion: This study identified different proteins associated with RFS depending on molecular subtype, smoking- and mutational-status, with PKC-α, PKC-β, and PKC-δ showing the strongest correlation.

Keywords: adenocarcinoma; expression subtypes; neuroendocrine markers; non-small cell lung cancer; protein kinase C; protein profiling; relapse free survival.