Expression of TARBP1 protein in human non-small-cell lung cancer and its prognostic significance

Abstract

The aim of the present study was to investigate the expression of transactivation response RNA-binding protein (TARBP)1 and its clinical significance in human non-small-cell lung cancer (NSCLC). TARBP1 expression at the mRNA level was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in 10 NSCLC tissues and paired adjacent normal tissues. TARBP1 protein expression was analyzed in 90 paraffin-embedded NSCLC tissue samples and paired adjacent normal tissues by immunohistochemistry. Statistical analyses were performed to assess the clinicopathological significance of TARBP1 expression. The expression of TARBP1 mRNA was higher in the 10 NSCLC samples than in the paired adjacent non-tumor tissues (P=0.0017). In the paraffin-embedded tissue samples, the expression level of TARBP1 was higher in the cancer tissues than in the adjacent non-cancerous tissues. TARBP1 expression was detected in 76.67% (69/90) of the NSCLC samples and in 22.22% (20/90) of the adjacent normal lung tissues (P<0.001). The expression of TARBP1 was significantly associated with histological grade (P<0.001), clinical stage (P=0.024) and pathological type (P<0.001), along with a decreased overall survival (OS) rate (P<0.001). On multivariate analysis, the expression of TARBP1 was an independent prognostic factor for hazard ratio (OS, 2.729; 95% confidence interval, 1.471-5.061; P=0.003). TARBP1 is overexpressed in NSCLC, and the expression of TARBP1 is associated with pathological grade, clinical stage and pathological type. Thus, TARBP1 may be an independent prognostic marker in patients with NSCLC.

Keywords: TARBP1; expression; non-small-cell lung cancer; prognosis.

Figure 1.

TARBP1 expression is upregulated in human lung cancer samples in the Oncomine database. Oncomine heat map of TARBP1 gene expression in clinical lung cancer samples compared with the normal lung tissues (www.oncomine.org). Sixteen sets of published mRNA expression data were chosen in this study. Significantly upregulated TARBP1 in cancer tissue samples compared with normal controls (>2-fold) were first selected. In the meta-analysis, TARBP1 expression was identified to be significantly higher in lung cancer than in the corresponding normal tissues with a median rank of 1862.5 and a P-value of 0.002. The degree of colour correlates to the gene rank percentile of the highest ranking analyses. The red colour represents overexpression of TARBP1 genes, and the blue colour represents underexpression of TARBP1 genes.

Figure 2.

Expression levels of TARBP1 mRNA in lung cancer and adjacent non-cancerous tissues. Expression levels of TARBP1 mRNA in 20 paired lung cancer tissues measured by real-time PCR. Normal, para carcinoma (normal) lung tissues. Tumor, lung cancer tissues.

Figure 3.

Expression status of TARBP1 in paired lung cancer and adjacent normal tissues. Immunohistochemical assay of TARBP1 protein expression in paired lung cancer and normal lung tissues. T, lung cancer tissues; ANT, matched adjacent non-tumor lung tissues (×40).

Figure 4.

Expression of TARBP1 protein measured by immunohistochemistry. TARBP1 expression was mainly localized in the cytoplasm of tumor cells. Negative expression of TARBP1 (A), low (B), medium (C) and high (D) expression of TARBP1 in lung cancer tissues (×200).

Figure 5.

Kaplan-Meier curves with univariate analysis (log-rank). (A) OS rates for cases with TARBP1 positive expression vs. those with TARBP1 negative expression in all patients. (B) OS rate for grade 1–2 cases with TARBP1 positive expression vs. those with TARBP1 negative expression. (C) OS rate for grade 3 cases with TARBP1 positive expression vs. those with TARBP1 negative expression. (D) OS rate for early clinical stage cases (stage I/II) with TARBP1 positive expression vs. those with TARBP1 negative expression. (E) OS rate for late stage cases (stage III/IV) with TARBP1 positive expression vs. those with TARBP1 negative expression.