Unbiased peptoid combinatorial cell screen identifies plectin protein as a potential biomarker for lung cancer stem cells

Tumors often contain a small subset of drug-resisting, self-renewing, and highly metastatic cells called tumor initiating cells or cancer stem cells (CSCs). To develop new approaches to detecting and targeting lung cancer CSCs, we applied an “unbiased” peptoid combinatorial cell screen to identify highly specific ligands that bind a CSC subpopulation of non-small cell lung cancer cells (defined by Aldefluor positivity), but not the remaining aldefluor negative cancer cells from the same preclinical model. One of the ‘hit’ peptoids bound to plectin, a structural protein, predominantly expressed intracellularly, but whose localization on the cell surface is linked to tumor invasion and metastasis. Our studies show both genotypic and phenotypic correlations between plectin and lung CSCs, as well as association of high plectin mRNA expression with poor patient survival in lung adenocarcinoma, potentially identifying plectin as a biomarker for lung CSCs.