Soluble Fas and Fas ligand provide new information on metastasis and response to chemotherapy in SCLC patients

Background: The Fas/Fas ligand (FasL) system is a major regulator of apoptosis. Chemotherapeutic drugs have been shown to induce Fas expression on the surface of lung cancer cells, and cancer cell apoptosis. However, this mechanism is not considered to be associated with Fas expressed on lung cancer cells. Soluble Fas and FasL concentrations are reportedly elevated in the peripheral blood of patients with lung cancer, but the roles of circulating soluble Fas and FasL in that disease have not been clarified. Materials and methods: We measured the circulating soluble Fas and FasL levels in 21 patients with small cell lung cancer (SCLC), and 12 healthy matched controls, in order to examine whether such ligands could provide any important information and/or reveal any new clinical features of SCLC. Results: In the CR patients, the neuronal specific enolase (NSE), soluble Fas and soluble FasL concentrations were 21.26 ± 3.65 ng/ml, 3.58 ± 0.19 ng/ml and 0.50 ± 0.15 ng/ml, while in the partial response (PR)/no change (NC)/progressive disease (PD) group of patients they were 33.96 ± 7.86 ng/ml, 5.29 ± 0.29 ng/ml and 0.59 ± 0.07 ng/ml, respectively. The NSE, soluble Fas and soluble FasL concentrations were all elevated in the PR/NC/PD patients, however, significant differences were only seen in Fas concentration between CR and PR/NC/PD patients and CR patients and the controls (p < 0.001). Conclusions: Serum soluble Fas and FasL play important roles in the proliferation and metastasis of SCLC, as well as in the cytotoxic reaction and apoptosis induced by anticancer drugs in SCLC. Further study of the mechanisms and participation of circulating soluble Fas and FasL is necessary to develop treatment strategies for SCLC.