Quantitative Detection of Interleukin 8 Gene Expression in Lung Cancer by Real-time Polymerase Chain Reaction

OBJECTIVE To develop a method for absolute quantification of interleukin 8 (IL-8) mRNA by using real-time polymerase chain reaction (PCR).

METHODS The IL-8 mRNA and protein expression in 2 human lung cancer cell Iines, H460 and A549, were evaluated by real-time PCR and ELISA. The IL-8 mRNA expression in 9 cases of normal lung tissue and 44 cases of non-small cell lung cancer (NSCLC) were examined.

RESULTS The IL—8 mRNA copy number in a given sample can be measured by real-time PCR. The gene expression of IL—8 is correlated with its protein secretion. The normalized value of IL—8 expression was 4.87±1.69 (copies/10⁴ GAPDH copies) in normal lung tissue and 17.04 ±23.96 in NSCLC, respectively. The difference between these two groups is statistically significant (P=0.002). Using 9.74 and 19.48 as cut-off points for positive expression and overexpression of IL—8, 52.3%(23/44cases) of NSCLC were found to express an increased level of IL-8, among which 29.5% (13/ 44cases) were defined as positive expression and 22.7%(10/44 cases) as overexpression. Statistical analysis indicated that IL—8 overexpression was significantly Increased In female cancers, squamous carcinoma, and in late stages of disease (P<0.05).

CONCLUSION The IL-8 gene expression can be determined by a real-time PCR technique. IL-8 overexpression is correlated with gender, histopathology and stages of the disease.