Largescale Transcriptomics Analysis Suggests Over-Expression of BGH3, MMP9 and PDIA3 in Oral Squamous Cell Carcinoma.

Oral squamous cell carcinoma (OSCC) has been reported as the most prevalent cancer of the head and neck region, while early diagnosis remains challenging. Here we took a comprehensive bioinformatics study on microarray data of 326 OSCC clinical samples with control of 165 normal tissues. The cell interaction pathways of ECM-receptor interaction and focal adhesion were found to be significantly regulated in OSCC samples. Further analysis of the topological properties and expression consistency identified that three hub genes in the gene interaction network, MMP9, PDIA3 and BGH3, were consistently up-expressed in OSCC samples. When being validated on additional microarray datasets of 41 OSCC samples, the validation rate of over-expressed BGH3, MMP9, and PDIA3 reached 90%, 90% and 84% respectively. At last, immuno-histochemical assays were done to test the protein expression of the three genes on newly collected clinical samples of 35 OSCC, 20 samples of pre-OSCC stage, and 12 normal oral mucosa specimens. Their protein expression levels were also found to progressively increase from normal mucosa to pre-OSCC stage and further to OSCC (ANOVA p = 0.000), suggesting their key roles in OSCC pathogenesis. Based on above solid validation, we propose BGH3, MMP9 and PDIA3 might be further explored as potential biomarkers to aid OSCC diagnosis

The three main dense modules of DEGs.

<p>Each circled or triangle point represents a node in the network and each line represents the interaction between two nodes. Red node: up-expressed gene; green node: down-expressed gene; gray node: background gene; triangle node: gene included in the enriched pathway.</p

Immunohistochemical labeling of normal oral mucosa (A,D,G), oral leukoplakia (B,E,H) and oral squamous cell carcinoma (G,H,I) for MMP9 (A,B,C), BGH3 (D,E,F) and PDIA3 (G,H,I).

<p>Brown staining represents positive expression of proteins. MMP9 expression in stroma cells is low (A). Positive MMP9 cytoplasmic staining of basal cells in OLK (B). Strong nuclear and cytoplasmic MMP9 staining of OSCC (C). Negative BGH3 expression in NOM (D). Weak or moderate BGH3 staining of the basement membrane in OLK (E). Strong positive BGH3 expression in tumor basement membrane and extracellular skeletal stroma of OSCC (F). Negative PDIA3 staining in NOM (G). Moderate to strong PDIA3 staining in the cytoplasm and nucleus of OLK epithelium cells (H). High PDIA3 expression in the cytoplasm and cell membrane of OSCC (I).</p