Lung adenocarcinoma is the most prevalent form of lung cancer, and drug resistance poses a significant obstacle in its treatment. This study aimed to investigate the overexpression of long non-coding RNAs (lncRNAs) as a mechanism that promotes intrinsic resistance in tumor cells from the onset of treatment. Drug-tolerant persister (DTP) cells are a subset of cancer cells that survive and proliferate after exposure to therapeutic drugs, making them an essential object of study in cancer treatment. The molecular mechanisms underlying DTP cell survival are not fully understood; however, long non-coding RNAs (lncRNAs) have been proposed to play a crucial role. DTP cells from lung adenocarcinoma cell lines were obtained after single exposure to tyrosine kinase inhibitors (TKIs; erlotinib or osimertinib). After establishing DTP cells, RNA sequencing was performed to investigate the differential expression of the lncRNAs. Some lncRNAs and one mRNA were overexpressed in DTP cells. The clinical relevance of lncRNAs was evaluated in a cohort of patients with lung adenocarcinoma from The Cancer Genome Atlas (TCGA). RT–qPCR validated the overexpression of lncRNAs and mRNA in the residual DTP cells and LUAD biopsies. Knockdown of these lncRNAs increases the sensitivity of DTP cells to therapeutic drugs. This study provides an opportunity to investigate the involvement of lncRNAs in the genetic and epigenetic mechanisms that underlie intrinsic resistance. The identified lncRNAs and CD74 mRNA may serve as potential prognostic markers or therapeutic targets to improve the overall survival (OS) of patients with lung cancer.

CD155, also known as the poliovirus receptor (PVR), is a crucial molecule in the development and progression of cancer, as its overexpression favors immune evasion and resistance to immunotherapy. However, little is known about the mechanisms that regulate its overexpression. Proinflammatory factors produced by various cellular components of the tumor microenvironment (TME) have been associated with CD155 expression. We analyzed the effect of interleukin (IL)-6 on CD155 expression in lung adenocarcinoma. We found a positive relationship between mRNA and protein levels. This correlation was also observed in bioinformatics analysis and in biopsies and serum from patients with lung adenocarcinoma. Interestingly, lung adenocarcinoma cell lines expressing suppressor of cytokine signaling 1 (SOCS1) did not show increased CD155 levels upon IL-6 stimulation, and SOCS1 silencing reverted this effect. IL-6 and SOCS1 are critical regulators of CD155 expression in lung adenocarcinoma. Further basic and clinical studies are needed to define the role of these molecules during tumor development and to improve their clinical impact as biomarkers and targets for predicting the efficacy of immunotherapies. This study deepens the understanding of the intricate regulation of the immune checkpoints mediated by soluble factors and allows us to devise new ways to combine conventional treatments with the most innovative anticancer options.