Expression of poly(C)-binding protein 1 (PCBP1) in NSCLC as a negative regulator of EMT and its clinical value

Abstract

Poly (C)-binding Protein 1 (PCBP1) is a 35 kDa protein involved in a number of biological processes. Recently, the research found that PCBP1 might be involved in epithelial-mesenchymal transition (EMT). However, the role of PCBP1 in non-small-cell lung cancer (NSCLC) metastasis needs further elucidation. The purpose of this study was to determine whether PCBP1 could serve as a biomarker for stratification and prediction of prognosis in NSCLC as a regulator of EMT formation. In this study, PCBP1 expression was evaluated by Western blot in 8 fresh lung cancer tissues and immunohistochemistry (IHC) on 145 paraffin-embedded slices. PCBP1 was highly expressed in non-metastatic NSCLC specimens and significantly correlated with lymph node status (P < 0.001), clinical stage (P = 0.001), vimentin expression (P = 0.033) and E-cadherin expression (P = 0.042). Our study showed that the low expression of PCBP1 was correlated with decreased expression of E-cadherin and elevated expression of vimentin, which were the markers of EMT. Besides, high expression of PCBP1 was correlated with better prognosis. These findings suggested that PCBP1 might play an important role in preventing the process of EMT in NSCLC, thus be a promising therapeutic target to inhibit NSCLC metastasis.

Keywords: EMT; Non-small-cell lung cancer; PCBP1; metastasis; prognosis.

Figure 1

Expressions of PCBP1 and E-cadherin in 8 NSCLC tissue specimens with or without lymph node metastasis. A representative Western blot image showed that the PCBP1 expression was significantly lower in metastatic tissues than in non-metastatic ones. E-cadherin was used as an epithilial marker. GAPDH was used as a control for protein load and integrity.

Figure 2

Immunohistochemical analysis of PCBP1, E-cadherin and vimentin expression in NSCLC tissues. A-F: Paraffin-embedded tissue sections were stained with antibodies of PCBP1, E-cadherin and vimentin, and counterstained with hematoxylin. A and C: Both high PCBP1 and E-cadherin expression in NSCLC specimens with no lymph node metastasis. B and D: Both low PCBP1 and E-cadherin expression in NSCLC specimens with lymph node metastasis. E: Low vimentin expression in NSCLC specimens with no lymph node metastasis. F: High vimentin expression in NSCLC specimens with lymph node metastasis. The experiment details were described in Materials and Methods. Magnification × 400. All the results were repeated at least three times.

Figure 3

Correlation between survival and the expression of PCBP1. Based on the mean percentage of PCBP1-positive cells, patients were divided into low PCBP1 expressers (scores 0-6) and high PCBP1 expressers (scores 7-12). Patients in the high PCBP1 expresser group had significantly better overall survival (P < 0.05).