LAMA4, highly expressed in human hepatocellular carcinoma from Chinese patients, is a novel marker of tumor invasion and metastasis

Abstract

Purpose: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in China. Hepatocarcinogenesis is correlated with a series of gene expression alteration. Here, we investigated LAMA4 gene expression in hepatocellular carcinoma on both mRNA and protein levels, expecting to explore the relationship between expressional abundances of LAMA4 and the clinical characteristics of HCC specimens.

Method: Total RNA was extracted from 48 cases of surgically resected HCC specimens and their corresponding peripheral tumor-free liver tissues. After the optimal reverse transcription polymerase chain reaction condition was established, the mRNA levels of LAMA4 in tumor and peripheral tumor-free tissues were examined semi-quantitatively. The relationship between expression levels of LAMA4 and clinical pathological characteristics was further analyzed by two-tailed t-test and chi2 test. We also used anti-LAMA4 antibody to detect the in vivo distribution of LAMA4 protein by tissue immunofluorescence staining in HCC specimens and their peripheral tumor-free tissues.

Results: The expression level of LAMA4 in 48 cases of human hepatocellular carcinoma tissues was significantly higher than that in their corresponding peripheral tumor-free tissues (0.37 +/- 0.25 vs. 0.18 +/- 0.12, P < 0.01). LAMA4 gene was up-regulated in 30 (62.50%) cases of HCC, down regulated in 4 (8.33%) cases, and showed no significant changes in 14 (29.17%) cases. Analysis of relationship between LAMA4 gene expression abundances and clinical characteristics by chi2 test showed that up-regulation of LAMA4 was strongly correlated with tumor invasion (79.31%), incomplete or no envelope (75.00%) and tumor bolt (86.67%). Additionally, tissue immunofluorescence staining against LAMA4 protein detected strong signal only in HCC tissues but not their corresponding peripheral tumor-free liver tissues. To our attention, LAMA4 protein showed specific in vivo distribution along the basement membrane of tumor blood vessels, bringing insights into its potential role in tumor angiogenesis.

Conclusions: LAMA4 is specifically up-regulated on both mRNA and protein levels in hepatocelluar carcinoma. The strong correlation between high expression abundances of LAMA4 with tumor invasion and metastasis, as well as, LAMA4 specific in vivo distribution in tumor basement membrane, indicated LAMA4's potential role in hepatocarcinogenesis and tumor progression. Therefore, we hypothesize that LAMA4 is probably a novel supplementary marker for HCC diagnosis, and might be a molecular target in the future cancer therapy.

Fig. 1

The genomic and cDNA structure of LAMA4 gene

Fig. 2

The expression of the LAMA4 gene in 48 cases of HCC (mRNA level )

Fig. 3

The expressional abundances of LAMA4 gene in mRNA level

Fig. 4

Analysis of relationship between the LAMA4 expression abundances and HCC clinical characteristics

Fig. 5

LAMA4 protein distribution in HCC tissues and their corresponding peripheral tumor-free liver tissues detected by tissue immunofluorescence staining. HCC tissue (Row a and c) was stained by polyclonal antibody against LAMA4 (a2, red) and normal rabbit IgG (c2, red) separately, counterstained by DAPI (a1 and c1, blue). The corresponding peripheral tumor-free liver tissue (Row b) was also stained by antibody against LAMA4, but showed no detectable signals. Line 3 gave the merge picture of DAPI staining and immunostaining