Differential expression of basement membrane collagen-IV α1 to α6 chains during oral carcinogenesis

Can immunohistochemistry serve as an alternative to subjective histopathological diagnosis of oral epithelial dysplasia?

Many attempts have been made to identify objective molecular biomarkers to diagnose and prognosticate oral epithelial dysplasia (OED) because histopathological interpretation is subjective and lacks sensitivity. The majority of these efforts describe changes in gene expression at protein level in OED as determined by immunohistochemistry (IHC). However, the literature on these putative markers of oral cancer progression is vast and varied. The main purpose of this article is to review current knowledge on biomarkers of protein expression for OED by IHC approaches. We further discuss these findings in terms of the proposed essential hallmarks of cancer cells to better understand their role in oral oncogenesis.

Comparative analysis of basal lamina type IV collagen α chains, matrix metalloproteinases-2 and -9 expressions in oral dysplasia and invasive carcinoma

The aim of this study was to compare the expressions of basal lamina (BL) collagen IV α chains and matrix metalloproteinases (MMP)-2 and MMP-9 in oral dysplasia (OED) and invasive carcinoma. Ten cases each of OEDs, carcinomas-in situ and oral squamous cell carcinomas (OSCCs) were examined by immunohistochemistry. Another 5 cases, each of normal and hyperplastic oral mucosa, served as controls. Results showed that α1(IV)/α2(IV) and α5(IV)/α6(IV) chains were intact in BLs of control and OEDs. In BLs of carcinoma-in situ, α1(IV)/α2(IV) chains preceded α5(IV)/α6(IV) chains in showing incipient signs of disruption. OSCCs exhibited varying degrees of collagen α(IV) chain degradation. MMP-2 and MMP-9 were absent in controls and OED, but weakly detectable in carcinoma-in situ. In OSCC, these proteolytic enzymes were expressed in areas corresponding to collagen α(IV) chain loss. Enzymatic activity was enhanced in higher grade OSCC, and along the tumor advancing front. Overall the present findings suggest that loss of BL collagen α(IV) chains coincided with gain of expression for MMP-2 and MMP-9, and that these protein alterations are crucial events during progression from OED to OSCC.

COL4A3 expression correlates with pathogenesis, pathologic behaviors, and prognosis of gastric carcinomas

COL4A3 protein belongs to type IV collagen family and is closely linked to kidney diseases and cancer. To clarify the roles of COL4A3 in gastric carcinogenesis and subsequent progression, its expression was examined by immunohistochemistry on tissue microarrays containing gastric carcinomas, adjacent intestinal metaplasia, pure intestinal metaplasia, and gastritis. Gastric carcinoma tissue and cell lines were studied for COL4A3 expression by Western blotting and reverse transcription-polymerase chain reaction. We found that COL4A3 was differentially expressed in GES-1, AGS, BGC-823, GT-3 TKB, HGC-27, KATO-III, MGC-803, MKN28, MKN45, SCH, SGC-7901, and STKM-2 at both messenger RNA and protein levels. Carcinomas showed statistically lower COL4A3 expression than matched nonneoplastic mucosa (P < .05). Expression was strong in intestinal metaplasia in comparison with gastritis and carcinoma (P < .05). There was greater COL4A3 expression in carcinoma than gastritis (P < .05). Expression of COL4A3 protein was positively correlated with tumor size, lymphatic invasion, venous invasion, and TNM stage (P < .05). There was more COL4A3 expression in diffuse than in intestinal-type carcinomas regardless of invasion into the muscularis propria (P < .05). Histologically, all signet ring cell (n = 43) and mucinous (n = 12) carcinomas showed COL4A3 expression. Kaplan-Meier analysis indicated that COL4A3 expression was negatively associated with a favorable prognosis of overall, advanced, and intestinal-type gastric carcinomas (P < .05). Aberrant COL4A3 expression might play an important role in the pathogenesis and subsequent progression of gastric carcinoma. COL4A3 overexpression might be used as a marker of gastric intestinal metaplasia and mucinous and signet ring cell carcinoma.

The expression of type IV collagen alpha6 chain is related to the prognosis in patients with esophageal squamous cell carcinoma

BACKGROUND

The destruction of the basement membrane (BM) is the first step in cancer cell invasion and metastasis. Type IV collagen is a major component of the BM, and is composed of six genetically distinct alpha(IV) chains: alpha1(IV) to alpha6(IV). The loss of alpha5/alpha6(IV) chains from the epithelial BM at the early stage of cancer cell invasion has been reported in several cancers. However, the expression of alpha5/alpha6(IV) chains in esophageal squamous cell carcinoma (ESCC) remains unclear.

METHODS

The expression of alpha(IV) chains in 116 resected ESCC specimens was immunohistochemically examined. The role of alpha6(IV) chain was assessed in ESCC cell lines by short interfering RNA (siRNA).

RESULTS

In intraepithelial carcinoma, the alpha5/alpha6(IV) chains were stained in a continuous linear pattern in the BM. In some cases of ESCC with the invasion beyond the lamina propria, the alpha5/alpha6(IV) chains were lost in the BM zone surrounding the cancer cell nests, but in other cases they remained. In the former, the disease-free survival and overall survival were significantly better than in those with the latter. The down-regulation of alpha6(IV) chain expression by siRNA revealed a slight increase of cancer cell invasiveness.

CONCLUSIONS

The evaluation of alpha5/alpha6(IV) chains may be a useful marker for determining tumor cell properties, as a prognostic factor, in patients with ESCC.