Polarization of Tumor Infiltrating Leukocytes from Innate Immunity and their role in the Pro-angiogenic Phenotype in NSCLC

Abstract

Non-small cell lung cancer (NSCLC), the most frequent lung cancer (80%), can be phenotypically classified into two main subtypes: squamous cell carcinoma (SCC) and adenocarcinoma (ADC). While SCC has relatively rapid doubling times from the onset, ADC has longer doubling times initially that become reduced during tumor progression, suggesting a key role for the microenvironment. During lung tumor progression, a complex and dynamic interplay occurs between proliferating tumor cells and stromal, endothelial and immune tumor-conditioned host cells within the tumor microenvironment (TUMIC). Several factors within the TUMIC, such as hypoxia, cytokines and soluble factors, appear to blunt the anti-tumor immune response and polarize immune cells towards a pro-tumor phenotype. Phenotypically and functionally altered immune cells found in cancer patients include macrophages, neutrophils, myeloid, dendritic, and even NK cells. We studied tumor infiltrating (TINK) and tumor associated (TANK) NK cells in NSCLC. NSCLC TINKs and TANKs show similarities to decidual NK cells, being polarized toward tissue builders, rather than killers, and producing pro-angiogenic cytokines. The functionally polarized immune cells in NSCLC provide the stromal support and neovascularization required for NSCLC tumor expansion and progression in a feed-forward mechanism, leading to tumor progression. Further, systemic alterations of immune cells are also present in NSCLC patients. The precise knowledge of these immune cell alterations within the TUMIC has become crucial for diagnosis, targeted therapeutic intervention, as well as prevention, of NSCLC cancer.