Department of Gastroenterological Surgery, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
Department of Surgery and Science, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan.
Ann Surg Oncol. 2022 May;29(5):2899-2909. doi: 10.1245/s10434-021-11152-1. Epub 2022 Jan 7.
Biliary tract cancer (BTC) has few choices of chemotherapy, including gemcitabine, therefore exploring the mechanisms of gemcitabine resistance is important. We focused on lipid metabolism because biliary tract epithelial cells are essential in cholesterol and bile acid metabolism and the messenger RNA (mRNA) microarray analysis showed high acyl coenzyme A: cholesterol acyltransferase 1 (ACAT-1) expression in BTC gemcitabine-resistant (GR) cell lines. We hypothesized that aberrant accumulation of cholesteryl ester (CE) regulated by ACAT-1 could modulate GR in BTC.
CE accumulations were measured in human BTC cell lines, and the relationships between CE levels, ACAT-1 expressions, and gemcitabine sensitivity were analyzed. We performed a small-interfering RNA (siRNA)-mediated knockdown and biochemical inhibition of ACAT-1 in BTC cell lines and alterations of gemcitabine sensitivity were evaluated. To evaluate the clinical significance of ACAT-1 in regard to GR, immunohistochemistry was performed and ACAT-1 expressions were analyzed in resected BTC specimens.
CE levels were correlated with ACAT-1 expressions and GR in four human BTC cell lines. siRNA-mediated knockdown of ACAT-1 in two independent GR cell clones as well as ACAT-1 inhibitor treatment significantly increased gemcitabine sensitivity; knockdown of ACAT-1: 5.63- and 8.02-fold; ACAT-1 inhibitor: 8.75- and 9.13-fold, respectively. ACAT-1 expression in resected BTC specimens revealed that the disease-free survival of the ACAT-1 low-intensity group (median 2.3 years) had a significantly better outcome than that of the ACAT-1 high-intensity group (median 1.1 years) under gemcitabine treatment after surgery (*p < 0.05).
Our findings suggest that CE and ACAT-1 might be a novel therapeutic target for GR in BTC.
胆管癌（BTC）的化疗选择有限，包括吉西他滨，因此探索吉西他滨耐药的机制很重要。我们专注于脂质代谢，因为胆管上皮细胞在胆固醇和胆汁酸代谢中是必不可少的，信使 RNA（mRNA）微阵列分析显示 BTC 吉西他滨耐药（GR）细胞系中酰基辅酶 A：胆固醇酰基转移酶 1（ACAT-1）表达较高。我们假设 ACAT-1 调节的胆固醇酯（CE）的异常积累可能调节 BTC 中的 GR。
在人 BTC 细胞系中测量 CE 积累，并分析 CE 水平、ACAT-1 表达与吉西他滨敏感性之间的关系。我们在 BTC 细胞系中进行了小干扰 RNA（siRNA）介导的 ACAT-1 敲低和生化抑制，并评估了吉西他滨敏感性的变化。为了评估 ACAT-1 在 GR 方面的临床意义，对切除的 BTC 标本进行了免疫组织化学分析并分析了 ACAT-1 的表达。
在四个人类 BTC 细胞系中，CE 水平与 ACAT-1 表达和 GR 相关。在两个独立的 GR 细胞克隆中 siRNA 介导的 ACAT-1 敲低以及 ACAT-1 抑制剂治疗均显著增加了吉西他滨的敏感性；敲低 ACAT-1：5.63-和 8.02 倍；ACAT-1 抑制剂：8.75-和 9.13 倍。切除的 BTC 标本中 ACAT-1 的表达显示，在手术后接受吉西他滨治疗时，ACAT-1 低强度组（中位 2.3 年）的无病生存期明显好于 ACAT-1 高强度组（中位 1.1 年）（*p <0.05）。
我们的研究结果表明，CE 和 ACAT-1 可能是 BTC 中 GR 的新治疗靶点。
