[Expression and clinical significance of nerve growth factor in primary liver cancer]

To determine the expression of nerve growth factor (NGF) in hepatic tissues and serum of patients with primary liver cancer (PLC), and to investigate the relationship of serum NGF levels with clinicopathological features of PLC.

Hepatocellular carcinoma (HCC) samples and patient-matched tumor-adjacent liver samples were collected from 26 PLC patients to assess the mRNA and protein expressions of NGF by reverse transcription-PCR, western blotting (b-actin normalized), and immunohistochemistry. In addition, serum samples were collected from 40 PLC patients, 40 liver cirrhosis patients, 40 chronic hepatitis patients (including hepatitis B or C virus infections), and 30 healthy (normal) controls. The serum levels of NGF were measured by enzyme-linked immunosorbent assay. Intergroup differences were assessed by the t-test, and correlation with sex, age, presence of cirrhosis, tumor size, and TNM classification were assessed by the Kruskal-Wallis H test followed the Mann-Whitney U test.

HCC tissues showed higher mRNA and protein expressions of NGF than the corresponding tumor-adjacent non-HCC tissues. Hepatic NGF expression was mainly localized to the tumor cell cytoplasm. Serum NGF expression was significantly higher in PLC patients (33.86+/-16.11 pg/ml) and cirrhosis patients (20.57+/-9.73 pg/ml) than in normal controls (11.13+/-6.12 pg/ml) and chronic hepatitis patients (13.20+/-6.23 pg/ml) (P less than 0.01). Furthermore, when the PLC patients were stratified according to tumor size and TNM stage, the serum NGF level was found to be significantly higher in patients with tumors more than 5 cm (vs. less than 5 cm; U=83.000, P=0.002) or of TNM stage III/IV (vs. stage I/II; U=103.500, P=0.009).

Elevated expression of NGF in liver cancer tissues and serum of PLC patients is related with tumor size and TNM staging. These findings suggest that NGF may play a role in HCC tumorigenesis and/or that serum NGF may represent a prognostic marker of PLC.