Associação Portuguesa de Investigação em Cancro
New insights into the inflamed tumor immune microenvironment of gastric cancer with lymphoid stroma: from morphology and digital analysis to gene expression
New insights into the inflamed tumor immune microenvironment of gastric cancer with lymphoid stroma: from morphology and digital analysis to gene expression

Authors and Affiliations:
Irene Gullo1,2,3,4, Patrícia Oliveira3,4, Maria Athelogou5, Gilza Gonçalves2,3,4,6, Marta L Pinto4,7,8, Joana Carvalho3,4, Ana Valente3,4, Hugo Pinheiro3,4,9, Sara Andrade3,4,10, Gabriela M. Almeida3,4, Ralf Huss5, Kakoli Das11, Patrick Tan11,12,13, José C. Machado2,3,4, Carla Oliveira2,3,4, Fátima Carneiro1,2,3,4
1Department of Pathology, Centro Hospitalar de São João, Al. Prof. Hernâni Monteiro, 4200-319 Porto, Portugal
2Department of Pathology, Faculty of Medicine of the University of Porto (FMUP), Al. Prof. Hernâni Monteiro, 4200-319 Porto, Portugal
3Institute of Molecular Pathology and Immunology at the University of Porto (Ipatimup), Rua Júlio Amaral de Carvalho 45, 4200-135 Porto, Portugal
4Instituto de Investigação e Inovação em Saúde (i3S), University of Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
5Definiens AG, Bernhard-Wicki Str 5, 80636 Munich, Germany
6Department of Biomedical Sciences and Medicine, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
7INEB-Institute of Biomedical Engineering, University of Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
8ICBAS-Institute of Biomedical Sciences Abel Salazar, University of Porto, Rua Jorge de Viterbo Ferreira 228, 4050-343 Porto, Portugal
9Hospital Senhora da Oliveira, Rua dos Cutileiros 114, 4835-044 Guimarães, Portugal
10 Department of Biomedicine, Faculty of Medicine of the University of Porto (FMUP), Al. Prof. Hernâni Monteiro, 4200-319 Porto, Portugal
11 Cancer and Stem Cell Biology Program, Duke-NUS Medical School, 8 College Road, 169857, Singapore
12 Genome Institute of Singapore, Biopolis, 60 Biopolis St, 138672, Singapore
13 Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Dr, 117599, Singapore
Abstract:
Background: Gastric cancer with lymphoid stroma (GCLS) is characterized by prominent stromal infiltration of T-lymphocytes. The aim of this study was to investigate GCLS biology through analysis of clinicopathological features, EBV infection, microsatellite instability (MSI), immune gene-expression profiling and PD-L1 status in neoplastic cells and tumor immune microenvironment.
Methods: Twenty-four GCLSs were analyzed by RNA in situ hybridization for EBV (EBER), PCR/fragment analysis for MSI, immunohistochemistry (PD-L1, cytokeratin, CD3, CD8), co-immunofluorescence (CK/PD-L1, CD68/PD-L1), NanoString gene-expression assay for immune related genes and PD-L1 copy number alterations. CD3+ and CD8+ T-cell densities were calculated by digital analysis. Fifty-four non-GCLSs were used as control group.
Results: GCLSs displayed distinctive clinicopathological features, such as lower pTNM stage (p = 0.02) and better overall survival (p = 0.01). EBV+ or MSI-high phenotype was found in 66.7 and 16.7% cases, respectively. GCLSs harbored a cytotoxic T-cell-inflamed profile, particularly at the invasive front of tumors (p < 0.01) and in EBV+ cases (p = 0.01). EBV+ GCLSs, when compared to EBV− GCLSs, showed higher mRNA expression of genes related to Th1/cytotoxic and immunosuppressive biomarkers. PD-L1 protein expression, observed in neoplastic and immune stromal cells (33.3 and 91.7%, respectively), and PD-L1 amplification (18.8%) were restricted to EBV+/MSI-high tumors and correlated with high values of PD-L1 mRNA expression.
Conclusions: This study shows that GCLS has a distinctive clinico-pathological and molecular profile. Furthermore, through an in-depth study of tumor immune microenvironment—by digital analysis and mRNA expression profiling—it highlights the role of EBV infection in promoting an inflamed tumor microenvironment, with putative therapeutic implications.
Revista: Gastric Cancer, 2018
Link: https://link.springer.com/article/10.1007/s10120-018-0836-8