Weiser T S, Ohnmacht G A, Guo Z S, Fischette M R, Chen G A, Hong J A, Nguyen D M, Schrump D S
Thoracic Oncology Section, Surgery Branch, National Cancer Institute, Bethesda, Maryland 20892-1502, USA.
Ann Thorac Surg. 2001 Jan;71(1):295-301; discussion 301-2. doi: 10.1016/s0003-4975(00)02421-8.
Although MAGE-3 has been detected in approximately 40% of lung and esophageal cancers, expression of this cancer testis antigen appears to be below the threshold for immune recognition in patients with these malignancies. The aim of this study was to determine if the demethylating agent, 5-Aza-2'-deoxycytidine (DAC) and if the histone deacetylase inhibitor Depsipeptide FR901228 (DP) could enhance MAGE-3 expression in lung and esophageal cancer cells.
Eleven lung and esophageal cancer lines and cultured normal human bronchial epithelial (NHBE) cells were exposed to normal media (NM), DAC, DP, or combination DAC/DP at varying concentrations and exposure durations. MAGE-3 expression was evaluated by quantitative RT-PCR (TaqMan) and immunohistochemistry techniques. Trypan blue exclusion techniques were used to examine the proliferation of cancer cells after drug exposure.
Relative to untreated controls, MAGE-3 expression was enhanced 32-fold (range 3.9 to 110) by DAC alone (0.1 micromol/L x 72 h), 2.1-fold (0.4 to 4.2) by DP alone (25 ng/mL x 6h), and 57-fold (4.6 to 209) by sequential DAC/DP exposure. Increased MAGE-3 mRNA copy numbers coincided with enhanced protein levels in these cells. MAGE-3 expression persisted after drug exposure. Flow cytometry confirmed the presence of functional HLA class I expression in these cells. Sequential DAC/DP treatment mediated pronounced growth inhibition in cancer cells but not NHBE.
Sequential DAC/DP treatment may be a novel strategy to simultaneously augment MAGE-3 expression and induce growth arrest in thoracic malignancies.
尽管在大约40%的肺癌和食管癌中检测到MAGE-3，但在这些恶性肿瘤患者中，这种癌胚抗原的表达似乎低于免疫识别阈值。本研究的目的是确定去甲基化剂5-氮杂-2'-脱氧胞苷（DAC）以及组蛋白脱乙酰酶抑制剂缩肽FR901228（DP）是否能增强肺癌和食管癌细胞中MAGE-3的表达。
将11种肺癌和食管癌细胞系以及培养的正常人支气管上皮（NHBE）细胞暴露于不同浓度和暴露时间的正常培养基（NM）、DAC、DP或DAC/DP组合中。通过定量逆转录聚合酶链反应（TaqMan）和免疫组织化学技术评估MAGE-3的表达。采用台盼蓝排斥技术检测药物暴露后癌细胞的增殖情况。
相对于未处理的对照组，单独使用DAC（0.1 μmol/L×72小时）可使MAGE-3表达增强32倍（范围为3.9至110），单独使用DP（25 ng/mL×6小时）可使其增强2.1倍（0.4至4.2），而序贯使用DAC/DP可使其增强57倍（4.6至209）。这些细胞中MAGE-3 mRNA拷贝数增加与蛋白水平增强相一致。药物暴露后MAGE-3表达持续存在。流式细胞术证实这些细胞中存在功能性HLA I类表达。序贯DAC/DP处理介导癌细胞显著生长抑制，但对NHBE细胞无此作用。
序贯DAC/DP处理可能是一种同时增强MAGE-3表达并诱导胸部恶性肿瘤生长停滞的新策略。
