Long non-coding RNA LINC01614 overexpression defines a ferroptosis-associated molecular signature in papillary thyroid cancer

Papillary thyroid cancer (PTC) is the most common endocrine malignancy, with incidence rising by approximately 3% each year. PTC disproportionately affects females of reproductive age, while male patients often exhibit more aggressive disease. Although overall survival is high, recurrence and metastasis remain significant clinical challenges that can persist for decades after initial diagnosis. Identifying reliable prognostic biomarkers and actionable therapeutic targets is therefore essential. Long non-coding RNAs (lncRNAs), a class of regulatory molecules with diverse roles in gene expression, display tissue- and cancer-specific expression patterns, making them promising candidates for biomarker discovery. Bioinformatic analysis of our PTC vs. normal thyroid genomic repository identified the lncRNA LINC01614 transcript as significantly 12-fold upregulated in PTC. Thus, we are studying LINC01614 as a potential PTC biomarker and/or therapeutic target. LINC01614 expression was found to be upregulated in multiple thyroid cancer cell lines. The PTC cell line K1 (~2 fold upregulated; BRAFV600E; male), was selected for in vitro study. CRISPR interference (CRISPRi) was used to transcriptionally repress LINC01614 in K1 cells. LINC01614 knockdown in K1 resulted in decreased migration (~20%), clonogenicity (~34%) and proliferation (~45%), indicating a role of this lncRNA in supporting malignant phenotypes. RNA sequencing analysis of a CRISPRi knockdown cell line vs. a CRISPRi control demonstrated reduced expression of key ferroptosis-related genes- SLC7A11 and SLC3A2. Both genes encode for the xCT system (cystine/glutamate reverse transporter) that regulates the uptake of cystine - a key precursor for glutathione (GSH) synthesis. GSH is a critical antioxidant defense against lipid peroxidation, further preventing ferroptosis. Thus, these findings suggested LINC01614 involvement in a ferroptosis-related mechanism. Consistent with this, total cell iron levels were quantified and found to be significantly higher in our LINC01614 knockdowns, signifying increased ferroptosis induction. Western blot analyses also showed decreased levels of ferroptosis-associated proteins such as GPX4, an important antioxidant enzyme that reduces lipid peroxidation to prevent ferroptosis. Current studies are ongoing to identify a LINC01614 mechanism of action within the ferroptosis pathway. These findings suggest that LINC01614 contributes to PTC pathogenesis through modulation of ferroptosis-related processes, highlighting its potential utility as a biomarker and/or therapeutic target.