Background and objective: Cathepsin X (Cat X) has been identified as a member of cathepsin family. Studies have shown that Cat X is involved in tumorigenesis and tumor development of various cancers. The aim of this study is to investigate the relationship between the clinicopathological prognosis and the levels of Cat X and cystatin C in the serum of patients with lung cancer.
Methods: Blood samples were collected from 84 patients with lung cancer and 36 healthy control subjects. Cat X and cystatin C were determined by quantitative ELISA.
Results: Cat X and cystatin C levels were significantly higher in the patients with lung cancer than that in the healthy control subjects (P<0.01). Cat X level was correlated with the pathological types of lung cancer (P=0.076). Cystatin C was positively correlated with TNM stage (P=0.01). Furthermore, cystatin C/Cat X was correlated with lymph node metastasis (P=0.058). The patients with high Cat X levels experienced significantly shorter overall survival rates compared with those with low Cat X. Univariate analysis indicated that Cat X and TNM stage were related to overall survival. Multivariate Cox analysis indicated that TNM stage may be used as an independent prognostic variable in patients with lung cancer.
Conclusions: Cat X and cystatin C levels were significantly higher in patients with lung cancer. Cat X and cystatin C detection in the sera may contribute to the diagnosis of lung cancer and may be used to evaluate the prognosis of patients with NSCLC.
背景与目的 组织蛋白酶X（Cathepsin X, Cat X）是最近发现的一种组织蛋白酶（Cathepsins, Cats）家族成员。近年来研究表明Cat X与多种恶性肿瘤发生、发展有关。本研究旨在探讨肺癌患者血清Cat X及cystatin C的表达与临床特征及预后的关系。方法 采用ELISA法定量检测84例肺癌患者及36例健康对照者血清Cat X及cystatin C表达。结果 肺癌患者血清Cat X和cystatin C水平明显高于健康人（P<0.01）；Cat X水平与肺癌病理类型之间有相关的趋势（P=0.076）。血清cystatin C水平与肺癌TNM分期正相关（P=0.01），cystatin C/Cat X与淋巴结转移之间有相关趋势（P=0.058）。Cat X表达水平与肺癌患者总生存期（overall survival, OS）相关，高水平Cat X肺癌患者OS更短。Cox单因素回归示Cat X高表达以及TNM分期是影响肺癌预后独立因素，Cox多因素回归显示，仅TNM分期是患者预后的独立危险因素。结论 肺癌患者中血清Cat X和cystatin C水平升高，检测肺癌患者Cat X和cystatin C血清水平对于指导临床肺癌诊断、评估预后有重要意义。