Department of Obstetrics/Gynecology and Reproductive Biology, Brigham and Women's Hospital, Boston, MA 02115, USA.
BMC Cancer. 2012 Aug 1;12:329. doi: 10.1186/1471-2407-12-329.
Aldehyde dehydrogenases belong to a superfamily of detoxifying enzymes that protect cells from carcinogenic aldehydes. Of the superfamily, ALDH1A1 has gained most attention because current studies have shown that its expression is associated with human cancer stem cells. However, ALDH1A1 is only one of the 19 human ALDH subfamilies currently known. The purpose of the present study was to determine if the expression and activities of other major ALDH isozymes are associated with human ovarian cancer and ovarian cancer sphere cultures.
Immunohistochemistry was used to delineate ALDH isozyme localization in clinical ovarian tissues. Western Blot analyses were performed on lysates prepared from cancer cell lines and ovarian cancer spheres to confirm the immunohistochemistry findings. Quantitative reverse transcription-polymerase chain reactions were used to measure the mRNA expression levels. The Aldefluor® assay was used to measure ALDH activity in cancer cells from the four tumor subtypes.
Immunohistochemical staining showed significant overexpression of ALDH1A3, ALDH3A2, and ALDH7A1 isozymes in ovarian tumors relative to normal ovarian tissues. The expression and activity of ALDH1A1 is tumor type-dependent, as seen from immunohistochemisty, Western blot analysis, and the Aldefluor® assay. The expression was elevated in the mucinous and endometrioid ovarian epithelial tumors than in serous and clear cell tumors. In some serous and most clear cell tumors, ALDH1A1 expression was found in the stromal fibroblasts. RNA expression of all studied ALDH isozymes also showed higher expression in endometrioid and mucinous tumors than in the serous and clear cell subtypes. The expression of ALDH enzymes showed tumor type-dependent induction in ovarian cancer cells growing as sphere suspensions in serum-free medium.
The results of our study indicate that ALDH enzyme expression and activity may be associated with specific cell types in ovarian tumor tissues and vary according to cell states. Elucidating the function of the ALDH isozymes in lineage differentiation and pathogenesis may have significant implications for ovarian cancer pathophysiology.
醛脱氢酶属于细胞解毒酶超家族，可保护细胞免受致癌醛类的侵害。在该超家族中，ALDH1A1 受到了最多的关注，因为目前的研究表明其表达与人类癌症干细胞有关。然而，ALDH1A1 只是目前已知的 19 个人类 ALDH 亚家族之一。本研究旨在确定其他主要 ALDH 同工酶的表达和活性是否与人类卵巢癌和卵巢癌球体培养物有关。
免疫组织化学用于描绘临床卵巢组织中 ALDH 同工酶的定位。对来自癌细胞系和卵巢癌球体的裂解物进行 Western Blot 分析，以确认免疫组织化学结果。使用定量逆转录聚合酶链反应测量 mRNA 表达水平。使用 Aldefluor® assay 测量四种肿瘤亚型中癌细胞的 ALDH 活性。
免疫组织化学染色显示，与正常卵巢组织相比，卵巢肿瘤中 ALDH1A3、ALDH3A2 和 ALDH7A1 同工酶的表达显著上调。从免疫组织化学、Western blot 分析和 Aldefluor® assay 可以看出，ALDH1A1 的表达和活性与肿瘤类型有关。在粘液性和子宫内膜样卵巢上皮肿瘤中，其表达高于浆液性和透明细胞肿瘤。在一些浆液性和大多数透明细胞肿瘤中，ALDH1A1 表达存在于基质成纤维细胞中。所有研究的 ALDH 同工酶的 RNA 表达也显示出在子宫内膜样和粘液性肿瘤中比在浆液性和透明细胞亚型中表达更高。在无血清培养基中作为球体悬浮液生长的卵巢癌细胞中，ALDH 酶的表达显示出与肿瘤类型有关的诱导。
我们的研究结果表明，ALDH 酶的表达和活性可能与卵巢肿瘤组织中的特定细胞类型有关，并根据细胞状态而有所不同。阐明 ALDH 同工酶在谱系分化和发病机制中的功能可能对卵巢癌病理生理学具有重要意义。
