BACKGROUND Lactate dehydrogenase C4 (LDH-C4) as a cancer/testis antigen (CTA) is abnormally expressed in some malignant tumors. However, the expression and clinical significance of LDH-C4 in breast cancer (BC) has not been characterized. METHODS We determined LDHC mRNA expression in serum and serum-derived exosomes of BC patients by quantitative RT-PCR. We also evaluated the protein expression of LDH-C4 in BC tissues using high-throughput tissue microarray analysis and immunohistochemistry. RESULTS Our results showed high mRNA expression level of LDHC in serum and serum-derived exosomes of BC patients. The LDHC level in serum and exosomes could distinguish BC cases from healthy individuals based on their AUCs of 0.9587 and 0.9464, respectively. Besides, the LDHC level in exosomes of BC patients associated with tumor size, and positively correlated with HER2 and Ki-67 expressions (all with P < 0.05). Serum and exosomal level of LDHC negatively correlated with medical treatment and positively with the recurrence of BC. Survival analysis showed that LDH-C4 expression negatively correlated with BC prognosis. CONCLUSION Serum and exosomal LDHC may be an effective indicator for the diagnosis, efficacy evaluation, and monitoring the recurrence of BC. LDH-C4 may act as a biomarker that predicts BC prognosis.

中文翻译：

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癌-睾丸抗原乳酸脱氢酶C4在乳腺癌中的诊断和预后价值。

背景技术乳酸脱氢酶C4（LDH-C4）作为癌症/睾丸抗原（CTA）在某些恶性肿瘤中异常表达。但是，LDH-C4在乳腺癌（BC）中的表达及其临床意义尚未得到表征。方法我们通过定量RT-PCR测定了BC患者血清和血清来源的外泌体中LDHC mRNA的表达。我们还使用高通量组织芯片分析和免疫组织化学评估了BC组织中LDH-C4的蛋白表达。结果我们的结果表明，BC患者血清和血清来源的外泌体中LDHC的mRNA表达水平较高。血清和外泌体中的LDHC水平可以根据健康人的AUC分别为0.9587和0.9464来区分BC病例和健康个体。此外，BC患者外泌体中的LDHC水平与肿瘤大小有关，与HER2和Ki-67的表达呈正相关（均P ＜0.05）。LDHC的血清和外泌体水平与药物治疗呈负相关，与BC的复发呈正相关。生存分析显示LDH-C4表达与BC预后呈负相关。结论血清和外泌体LDHC可能是诊断，疗效评估和监测BC复发的有效指标。LDH-C4可以作为预测BC预后的生物标志物。疗效评估，并监测BC的复发。LDH-C4可以作为预测BC预后的生物标志物。疗效评估，并监测BC的复发。LDH-C4可以作为预测BC预后的生物标志物。