Tehran University of Medical Sciences Acta Biochimica Iranica 0001-5261 3 3 2025 09 20 150 154 Maryam Mohammadhosseini Islamic Azad University, Tehran, Iran Nasrin Shayanfar Iran University of Medical Sciences, Tehran, Iran Roya Sharifi Iran University of Medical Science 2025 09 24 2025 10 27 Objectives: Long non-coding RNAs (lncRNAs) play critical roles in tumor development, progression, and prognosis. Prostate cancer gene expression marker 1 (PCGEM1) is an oncogenic lncRNA that inhibits apoptosis, whereas lincRNA-p21 promotes apoptosis. This study aimed to investigate the expression of these lncRNAs in breast tumor tissue and adjacent non-tumor tissue. Methods: The expression levels of PCGEM1 and lincRNA-p21 were assessed by real-time PCR (RT-PCR) in fifty formalin-fixed, paraffin-embedded invasive ductal carcinoma breast tumor tissues and adjacent non-tumor tissues.  Results: The expression of PCGEM1 was significantly higher in tumor tissues compared to adjacent non-tumor tissues (p=0.01). ROC curve analysis indicated that the sensitivity and specificity of PCGEM1 for discriminating breast cancer were %60.87 and 70.21%, respectively, with an area under the curve (AUC) of 0.63 (p=0.01). No significant correlation was observed between PCGEM1 expression and tumor size, histological grade, or lymph node involvement. The expression of lincRNA-p21 was similar in tumor tissues and adjacent non-tumor tissues. Conclusions:  PCGEM1 may contribute to the pathogenesis of breast cancer and could serve as a diagnostic marker in breast cancer. https://abi.tums.ac.ir/index.php/abi/article/view/161 https://abi.tums.ac.ir/index.php/abi/article/download/161/118