Wulf G G, Jürgens B, Liersch T, Gatzemeier W, Rauschecker H, Buske C, Hüfner M, Hiddemann W, Wörmann B
Department of Internal Medicine, Georg-August-Universität, Göttingen, Germany.
J Cancer Res Clin Oncol. 1997;123(9):514-21. doi: 10.1007/BF01192207.
Tumor cell dissemination in the bone marrow is an independent prognostic marker for relapse and survival for patients with primary breast cancer. Parathyroid-hormone-related protein (PTHrP) is expressed in most primary tumors and bone metastases of patients with breast cancer. PTHrP acts as an autocrine growth factor for breast cancer cells in vitro and there is evidence that it is especially important for osseous metastasis. For a sensitive detection of PTHrP-positive disseminated tumor cells a reverse transcriptase/polymerase chain reaction (RT/PCR) assay for PTHrP transcripts in the peripheral blood (PB) and in the bone marrow (BM) has been established. In mixing studies, the sensitivity of the reverse transcriptase/polymerase chain reaction (RT/PCR) for PTHrP was one tumor cell in 1 x 10(6) mononuclear cells. At this level of sensitivity, transcripts of PTHrP were detected in none of 30 PB samples and in 3 of 25 BM samples of healthy volunteers; there were also no transcripts of PTHrP in the PB and BM of 6 patients with benign breast lesions. The PB samples of 31 patients and the BM samples of 34 patients with predominantly early-stage breast cancer were tested for PTHrP expression along with immunocytology against cytokeratin 18 (CK18) as a standard immunological detection technique. PTHrP expression was shown in 9 of 31 patients in the PB and in 9 of 34 patients in the BM. In 30 patients, PB and BM samples were available simultaneously. There were cases of combined positive findings in the PB and the BM (4/30) and of isolated positivity in the PB (5/30) or in the BM (4/30). Compared to immunocytology, RT/PCR assay of PTHrP assay was significantly more sensitive in the peripheral blood (8/30 by RT/PCR compared to 1/30 by immunocytology). In the bone marrow there were cases of positivity for both markers (2/34), cases of isolated positivity by immunocytology for CK18 (3/34) and cases of isolated positivity for PTHrP transcripts (7/34). In conclusion the RT/PCR assay for PTHrP transcripts is a feasible and very sensitive technique for the detection of tumor cell dissemination in the PB, even in patients with early-stage breast cancer. The specificity of detection of PTHrP transcripts in the bone marrow is limited, possibly because of autochthonous expression of PTHrP in osteoblastic cells. The clinical follow-up of the subgroups of patients at risk, as defined by this assay, will show its prognostic significance for patients with breast cancer.
肿瘤细胞在骨髓中的播散是原发性乳腺癌患者复发和生存的独立预后标志物。甲状旁腺激素相关蛋白（PTHrP）在大多数乳腺癌患者的原发性肿瘤和骨转移灶中表达。PTHrP在体外作为乳腺癌细胞的自分泌生长因子，有证据表明它对骨转移尤为重要。为了灵敏检测PTHrP阳性的播散肿瘤细胞，已建立了一种用于检测外周血（PB）和骨髓（BM）中PTHrP转录本的逆转录酶/聚合酶链反应（RT/PCR）检测方法。在混合研究中，RT/PCR检测PTHrP的灵敏度为1×10⁶个单核细胞中有一个肿瘤细胞。在这种灵敏度水平下，30份健康志愿者的外周血样本中均未检测到PTHrP转录本，25份健康志愿者的骨髓样本中有3份检测到；6例乳腺良性病变患者的外周血和骨髓中也未检测到PTHrP转录本。对31例主要为早期乳腺癌患者的外周血样本和34例患者的骨髓样本进行了PTHrP表达检测，并采用针对细胞角蛋白18（CK18）的免疫细胞化学方法作为标准免疫检测技术。31例患者的外周血中有9例检测到PTHrP表达，34例患者的骨髓中有9例检测到。30例患者同时获得了外周血和骨髓样本。存在外周血和骨髓联合阳性结果的病例（4/30），以及外周血（5/30）或骨髓（4/30）单独阳性的病例。与免疫细胞化学相比，PTHrP的RT/PCR检测在外周血中显著更灵敏（RT/PCR检测为8/30，免疫细胞化学检测为1/30）。在骨髓中，有两种标志物均阳性的病例（2/34），CK18免疫细胞化学单独阳性的病例（3/34），以及PTHrP转录本单独阳性的病例（7/34）。总之，检测PTHrP转录本的RT/PCR检测方法是一种可行且非常灵敏的技术，可用于检测外周血中的肿瘤细胞播散，即使是早期乳腺癌患者。在骨髓中检测PTHrP转录本的特异性有限，可能是由于成骨细胞中PTHrP的自身表达。通过该检测方法定义危险患者亚组并进行临床随访，将显示其对乳腺癌患者的预后意义。
