Abstract:
Backgroung: Under physiological conditions, leukocytes contribute to the majority of circulatng DNA in plasma. Therefore, detection of SHP-1 promoter-2 (SHP1P2) methylaton to represent epithlial tumor-derived circulatng nucleic acid may serve as a potential plasma biomarker for epithelial-derved cancer. Furthermore the fraction of caner cel-derived and inflammatory cell-derved nucleic acid was still enigmatic. Total amount of circulating nucleic acid was increased in cancer patient and it was correlated with prognostic outcome in various types of cancer. These might be the effect of tumor-derved nucleic acid, correlated with tumor burden; however the interaction of cancer and immune cell was not negligent. Materials and method: A dual hybridization probe and real-time quantitative PCR-based assay was used to determine the level of SHP1P2 methylation in plasma. Blood samples were prospectively collected from 58 advanced NSCLC patients and 52 healthy control. Clinicopathological data and outcome of treatment were included in the anaysis. Results: The levels of SHP1P2 methylation in plasma from controls were mostly undetectable. In contrast to the NSCLC patients. SHP1P2 methylation was significantly higher than tha of controls. Pretreatment level of the SHP1P2 methylation was significant associated wth the survival. Patients who had SHP1P2 methylaton < 0.7m ml-1 had better progression-free survival (5.2 vs. 2.6 months, p = 0.009) and overal survival (12.6 vs. 7.6 months, p = 0.01). SHP1P2 methylaton was the only independent predictive factor of survival by multvarate analysis. Moreover circulating DNA evel was also correlated with survival outcome however less specific than SHP1P2 methylation. The follow-up level correlated well with reponse of treatment. This influenced by the impact of tumor-derived and inflammatory cell-derived nucleic acid. Conclusion: Measurement plasma SHP1P2 methyation may serve as a potential non-invasive biomarker for the diagnosis and prognosis assessment in lung cancer patients adding to circulatng DNA level. This classification may serve as a biomarker for risk-adaptive treatment
