Zhang Daohai, Wong Lee Lee, Koay Evelyn S C
Department of Laboratory Medicine, National University Hospital, 5 Lower Kent Ridge Road, 119074, Singapore.
Mol Cancer. 2007 Aug 14;6:52. doi: 10.1186/1476-4598-6-52.
Abnormal amplification/expression of HER-2/neu oncogene has been causally linked with tumorigenesis and metastasis in breast cancer and associated with shortened overall survival of patients. Recently, heat shock protein 27 (Hsp27) was reported to be highly expressed in HER-2/neu positive tumors and cell lines. However, putative functional links between phosphorylation of Hsp27 with HER-2/neu status and other clinicopathological features remain to be elucidated.
Comparative phosphoproteomic studies of HER-2/neu positive and -negative breast tumors revealed that Hsp27, one of the identified phosphoproteins, was highly phosphorylated in HER-2/neu positive tumors. The extent of Hsp27 phosphorylation at its Ser15, Ser78 and Ser82 residues were further evaluated with site-specific antibodies in tumor samples by tissue lysate array- and tissue microarray-based analyses, and in the BT474 breast cancer cell line treated with heregulin alpha1 (HRG alpha1) or the p38 MAPK inhibitor, SB203580. The tissue lysate array study indicated that only the level of pSer78 in HER-2/neu positive tumors was more than 2-fold that in HER-2/neu negative tumors. Treatment of BT474 cells with HRG alpha1 and SB203580 indicated that Ser78 phosphorylation was mainly regulated by the HER-2/neu-p38 MAPK pathway. Immunohistochemical staining of sections from a tissue microarray with 97 breast tumors showed that positive staining of pSer78 significantly correlated with HER-2/neu (p = 0.004) and lymph node positivity (p = 0.026).
This investigation demonstrated the significant correlation of enhanced phosphorylation of the Ser78 residue of Hsp27 with HER-2/neu and lymph node positivity in breast cancer.
HER-2/neu癌基因的异常扩增/表达与乳腺癌的肿瘤发生和转移存在因果关系，并与患者总体生存期缩短相关。最近，有报道称热休克蛋白27（Hsp27）在HER-2/neu阳性肿瘤和细胞系中高表达。然而，Hsp27磷酸化与HER-2/neu状态及其他临床病理特征之间的潜在功能联系仍有待阐明。
对HER-2/neu阳性和阴性乳腺肿瘤进行比较磷酸化蛋白质组学研究发现，所鉴定出的磷酸化蛋白之一Hsp27在HER-2/neu阳性肿瘤中高度磷酸化。通过组织裂解物芯片和组织微阵列分析，利用位点特异性抗体在肿瘤样本中进一步评估了Hsp27在其Ser15、Ser78和Ser82残基处的磷酸化程度，并在经这里配体α1（HRGα1）或p38丝裂原活化蛋白激酶（MAPK）抑制剂SB203580处理的BT474乳腺癌细胞系中进行了评估。组织裂解物芯片研究表明，HER-2/neu阳性肿瘤中pSer78的水平仅比HER-2/neu阴性肿瘤中的水平高出2倍以上。用HRGα1和SB203580处理BT474细胞表明，Ser78磷酸化主要受HER-2/neu-p38 MAPK途径调控。对包含97例乳腺肿瘤的组织微阵列切片进行免疫组织化学染色显示，pSer78阳性染色与HER-2/neu（p = 0.004）和淋巴结阳性（p = 0.026）显著相关。
本研究表明，Hsp27的Ser78残基磷酸化增强与乳腺癌中的HER-2/neu及淋巴结阳性显著相关。
