Elevated levels of circulating plasma matrix metalloproteinase 9 in non-small cell lung cancer patients

Elevated expression levels of matrix metalloproteinase (MMP)-2 and MMP-9 ha ve been implicated as playing important roles in tumor invasion and metasta sis in various tissues. We investigated the relationship between circulatin g plasma MMP-9, its expression in tumor samples, and other clinical feature s in patients with non-small cell lung cancer (NSCLC), A series of 73 patie nts (45 men and 28 women) who underwent surgery for NSCLC was used in this study. Preoperative plasma concentrations of hlh;UP-9 were examined using a one-step sandwich enzyme immunoassay. Expression levels of MMP-2, MMP-9, t issue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 were measured in 2 4 tumor samples by immunohistochemistry. The plasma concentration of MMP-9 in NSCLC patients (71.0 +/- 60.2 ng/ml) was significantly elevated compared to that of healthy volunteers (P < 0.0001), MMP-9 concentrations were elev ated in 33 of 73 cases (45.2%), compared with a cutoff value of the mean +/ - 2 SD in healthy volunteers. There were statistically significant differen ces in MMP-9 concentration in adenocarcinoma versus squamous cell carcinoma (P 0.014) and adenocarcinoma versus large cell carcinoma (P = 0.014), Five of 24 patients (20.8%) had positive immunohistochemical MMP staining of th e tumor cell cytoplasm, and two cases had positive staining in the surround ing stromal cells. Plasma MMP-9 concentrations were elevated in 45.2% of NS CLC patients; however, this elevation did not seem to correlate with MMP-9 production by cancer and stromal cells. Ne concluded that the MMP-9 ELISA c ould be a beneficial adjunct for assessing the tumor burden of NSCLC, espec ially for types of squamous cell carcinoma and large cell carcinoma.