乳腺癌是全球女性发病率和死亡率的主要原因。发现新的分子标志物可以帮助癌症的诊断、靶向治疗和治疗监测。本研究旨在测量X框结合蛋白1（XBP1）基因的表达，以及长非编码RNA（lncRNA），包括核富集丰度转录本1（NEAT1）、癌症易感候选基因2（CASC2）和长间隔非蛋白编码RNA 299（LINC00299），作为可能的调控物反应（UPR）通路。从40份乳腺肿瘤组织样本及其对应的对照中提取总RNA。使用逆转录-聚合酶链反应（RT-PCR）定量lncRNAs CASC2、NEAT1和LINC00299的表达水平。通过PCR和电泳确定XBP1剪接形式与未剪接形式（XBP1u）的比值。结果显示，与相邻的非恶性样本相比，乳腺癌组织中XBP1s/u比值增加了2.8倍（p < 0.05）。此外，与相邻的非恶性样本相比，乳腺肿瘤组织中NEAT1、CASC2和LINC00299的水平分别显著增加了两倍、1.5倍和2.3倍（p < 0.05）。根据CASC2、LINC00299和NEAT1的表达与XBP1s/u比值的关联，这些lncRNAs可能是UPR通路的潜在调节因子。此外，由于在癌症样本中与相邻的非癌组织相比表达显著增加，可以将CASC2和NEAT1基因作为区分癌组织和非癌乳腺组织的合适生物标志物。© 2023 The Authors. Health Science Reports由Wiley Periodicals LLC出版。

Breast cancer is a leading cause of incidence and mortality in women globally. Identifying new molecular markers can aid in cancer diagnosis, targeted therapy, and treatment monitoring. This study aimed to measure the expression of the X-box binding protein 1 (XBP1) gene, an index of the unfolded protein response (UPR), and long noncoding RNAs (lncRNAs), including Nuclear Enriched Abundant Transcript 1 (NEAT1), Cancer Susceptibility Candidate 2 (CASC2), and Long Intergenic Nonprotein Coding RNA 299 (LINC00299), as possible regulators of the UPR pathway.Total RNA was extracted from 40 samples of breast tumor tissues and their respective controls. The expression level of lncRNAs CASC2, NEAT1, and LINC00299 was quantified using reverse transcription-polymerase chain reaction (RT-PCR). The ratio of the spliced form of XBP1 to its unspliced form (XBP1u) was determined by PCR and electrophoresis.The results showed a 2.8-fold increase in the ratio of XBP1s/u in breast cancer tissues compared to adjacent nonmalignant samples (p < 0.05). Additionally, the level of lncRNAs NEAT1, CASC2, and LINC00299 in breast tumor tissues increased significantly by twofold, 1.5-fold, and 2.3-fold, respectively, compared to adjacent nonmalignant samples (p < 0.05).Based on the association between the expression of lncRNAs CASC2, LINC00299, and NEAT1 and the XBP1s/u ratio, these lncRNAs could be potential regulators of the UPR pathway. Also, CASC2 and NEAT1 genes could be suggested as suitable biomarkers to distinguish cancerous tissue from noncancerous breast tissue due to their significant increase in expression in cancerous samples compared to adjacent noncancerous.© 2023 The Authors. Health Science Reports published by Wiley Periodicals LLC.