Litle V R, Warren R S, Moore D, Pallavicini M G
Department of Surgery, University of California, San Francisco 94143-0808, USA.
Cancer. 1997 May 1;79(9):1664-70.
Low frequency epithelial cells in bone marrow from colorectal carcinoma patients are associated with an increased risk of recurrence and decreased survival. Current immunohistochemical approaches to detect epithelial cells in bone marrow aspirates rely on antibodies against cytokeratin 18 (CK18). The predictive value of CK18-based detection strategies is limited by false-positives that occur in approximately 30% of cases. Cross-reactivity of anti-CK18 antibodies with nontumor cells may contribute to the false-positive rate. Cytokeratin 20 (CK20) shows more restricted expression than CK18 and labels cells in colorectal tumors.
Immunofluorescence assays were used to quantify CK20-labeled cells in bone marrow aspirates and tumors from 18 Dukes stage C and D colorectal carcinoma patients to determine whether CK20 is useful in detecting micrometastases. Fluorescent in situ hybridization was used to determine whether CK-labeled subpopulations carried genomic aberrations associated with colorectal carcinoma.
CK20-labeled cells occurred at frequencies approximately 5 x 10(-5) in control bone marrow aspirates from patients without colorectal carcinomas. Approximately 10(-4) CK20-labeled cells were present in 4 of 11 bone marrow aspirates (45%) from patients with Dukes stage D colon carcinoma. The mean frequency (5 x 10(-5) of CK20-labeled cells in Dukes stage C and D rectal carcinoma patients was statistically similar to control values. CONCLUSIONS. A subset of CK20-labeled cells in primary tumors and hepatic metastases are aneusomic. CK20-labeled cells in bone marrow aspirates are cytogenetically normal. These data demonstrate that CK20 cells in solid tumors may be cytogenetically aberrant, but suggest caution in the use of CK20 to detect micrometastases in bone marrow aspirates.
结直肠癌患者骨髓中的低频上皮细胞与复发风险增加及生存率降低相关。目前用于检测骨髓穿刺物中上皮细胞的免疫组化方法依赖于抗细胞角蛋白18（CK18）抗体。基于CK18的检测策略的预测价值受到约30%病例中出现的假阳性的限制。抗CK18抗体与非肿瘤细胞的交叉反应可能导致假阳性率升高。细胞角蛋白20（CK20）的表达比CK18更具局限性，且能标记结直肠癌中的细胞。
采用免疫荧光测定法对18例杜克分期C期和D期结直肠癌患者的骨髓穿刺物和肿瘤中的CK20标记细胞进行定量，以确定CK20是否有助于检测微转移。采用荧光原位杂交法确定CK标记的亚群是否携带与结直肠癌相关的基因组畸变。
在无结直肠癌患者的对照骨髓穿刺物中，CK20标记细胞的出现频率约为5×10⁻⁵。在11例杜克分期D期结肠癌患者的骨髓穿刺物中，有4例（45%）存在约10⁻⁴的CK20标记细胞。杜克分期C期和D期直肠癌患者中CK20标记细胞的平均频率（5×10⁻⁵）在统计学上与对照值相似。结论：原发性肿瘤和肝转移灶中一部分CK20标记细胞为非整倍体。骨髓穿刺物中CK20标记细胞的细胞遗传学正常。这些数据表明实体瘤中的CK20细胞可能存在细胞遗传学畸变，但在使用CK20检测骨髓穿刺物中的微转移时建议谨慎。
