近日，日本北里大學(xué)的Yuichi Sato開展了一項(xiàng)尋找肺癌血清診斷標(biāo)識物的研究,。該研究發(fā)現(xiàn),，CAXII就是要尋找的標(biāo)記物。相關(guān)研究發(fā)表在3月16日的美國《公共科學(xué)圖書館·綜合》（PLoS One）上,。
為了發(fā)展一種肺癌血清診斷的標(biāo)識物,，Yuichi Sato等人利用肺腺癌(AD)派生的A549細(xì)胞作為抗原，使用隨機(jī)免疫方法得到了單克隆抗體,。隨后,，使用免疫組化方法，用雜交瘤細(xì)胞上清液來篩查抗體,。篩選出的陽性克隆被有限稀釋法（limiting dilutions）克隆兩次,，以確保是單克隆。
從獲得的單克隆抗體中,，研究人員挑選了一種能夠強(qiáng)烈結(jié)合A549細(xì)胞膜的抗體,，稱為KU-Lu-5?；诿庖叱恋矸磻?yīng)以及MADLI TOF/TOF-MS分析,，這種抗體被發(fā)現(xiàn)是碳酸酐酶XII (CAXII)。為了評價(jià)這種抗體作為肺癌血清標(biāo)志物的效用,，他們利用斑點(diǎn)印跡,，對一組來自于70個肺癌病人和30個健康對照的血清進(jìn)行研究。
實(shí)驗(yàn)結(jié)果表明：肺癌患者中的CAXII表達(dá)水平顯著高于健康對照中的,。為了進(jìn)一步確認(rèn)血清CAXII水平作為血清診斷標(biāo)識物的實(shí)用性,，研究人員開展了一個額外的效度研究實(shí)驗(yàn)。該實(shí)驗(yàn)利用斑點(diǎn)免疫,，分析了來自26個肺癌患者及30個健康對照的血清,，實(shí)驗(yàn)結(jié)果與預(yù)想一致。
因此,，本次實(shí)驗(yàn)表明：CAXII應(yīng)該可以作為可適用的肺癌患者識別標(biāo)記,。而且，這是第一份報(bào)告證明CAXII很可能是一個新的肺癌血清診斷標(biāo)記物,。（生物谷Bioon.com）
doi: 10.1371/journal.pone.0033952
PMC:
PMID:
CAXII Is a Sero-Diagnostic Marker for Lung Cancer
Makoto Kobayashi, Toshihide Matsumoto, Shinichiro Ryuge, Kengo Yanagita, Ryo Nagashio, Yoshitaka Kawakami, Naoki Goshima, Shi-Xu Jiang, Makoto Saegusa, Akira Iyoda, Yukitoshi Satoh, Noriyuki Masuda, Yuichi Sato.
To develop sero-diagnostic markers for lung cancer, we generated monoclonal antibodies using pulmonary adenocarcinoma (AD)-derived A549 cells as antigens by employing the random immunization method. Hybridoma supernatants were immunohistochemically screened for antibodies with AMeX-fixed and paraffin-embedded A549 cell preparations. Positive clones were monocloned twice through limiting dilutions.From the obtained monoclonal antibodies, we selected an antibody designated as KU-Lu-5 which showed intense membrane staining of A549 cells. Based on immunoprecipitation and MADLI TOF/TOF-MS analysis, this antibody was recognized as carbonic anhydrase XII (CAXII). To evaluate the utility of this antibody as a sero-diagnostic marker for lung cancer, we performed dot blot analysis with a training set consisting of sera from 70 lung cancer patients and 30 healthy controls.The CAXII expression levels were significantly higher in lung cancer patients than in healthy controls in the training set (P<0.0001), and the area under the curve of ROC was 0.794, with 70.0% specificity and 82.9% sensitivity. In lung cancers, expression levels of CAXII were significantly higher in patients with squamous cell carcinoma (SCC) than with AD (P = 0.035). Furthermore, CAXII was significantly higher in well- and moderately differentiated SCCs than in poorly differentiated ones (P = 0.027).To further confirm the utility of serum CAXII levels as a sero-diagnostic marker, an additional set consisting of sera from 26 lung cancer patients and 30 healthy controls was also investigated by dot blot analysis as a validation study. Serum CAXII levels were also significantly higher in lung cancer patients than in healthy controls in the validation set (P = 0.030).Thus, the serum CAXII levels should be applicable markers discriminating lung cancer patients from healthy controls. To our knowledge, this is the first report providing evidence that CAXII may be a novel sero-diagnostic marker for lung cancer
