Electrophoretic analysis of the cleaved form of serpin, squamous cell carcinoma antigen‐1 in normal and malignant squamous epithelial tissues

Abstract

The aim of this study was to detect the cleaved form of serine proteinase inhibitor (serpin), squamous cell carcinoma (SCC) antigen-1 in normal and malignant squamous epithelial tissues, which implies the presence of its target proteinase. The cleaved SCC antigen-1 in normal squamous epithelium was identified as a single spot with pI 6.35 and M(r) 40,000 by two-dimensional electrophoresis (2-DE) combined with immunoblotting. Interestingly, the cleaved form showed different biochemical properties in heat stability or immunoreactivity with a monoclonal antibody for SCC antigen (Mab 426) compared to intact SCC antigen-1. Furthermore, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of tissue extracts showed an abundant 40 kDa band of cleaved SCC antigen-1 in tumor tissue compared to normal tissue. Among the potential target proteinase of SCC antigen-1, immunoblotting analyses revealed that cathepsin L2 was remarkably overexpressed in tumor tissue, while cathepsin L was expressed in both normal and tumor tissues. These findings indicate that SCC antigen-1 interacts with specific endogenous proteinases such as cathepsins L and L2 in physiological and pathological states of squamous epithelium.

Different expression patterns of intact forms of squamous cell carcinoma antigens between normal and malignant cervical squamous epithelial tissues: Nondenaturing polyacrylamide gel electrophoretic analysis

“…Characterization of a novel specific antibody, Pab Y2, by 2-DE combined with immunoblotting. Pab Y2 recognized intact forms of both SCCA1 and SCCA2 in normal cervical squamous epithelial tissue, but not the cleaved form of SCCA1 (arrow), which was detected by Mab 27, as reported previously (17).…”

“…We used specific monoclonal antibodies, Mab 27 and Mab 426. We previously reported that Mab 27 reacted with both intact and cleaved forms of SCCAs, while Mab 426 reacted with cleaved forms of SCCAs, but not with intact SCCAs (17). To yield the novel antibody specific for intact forms of SCCAs, Pab Y2 was newly generated by immunizing with keyhole limpet hemocyanineconjugated to the synthetic peptide corresponding to a region from the C-terminal fragment of SCCA2 to rabbit and purified using the peptide affinity column.…”

“…Using two-dimensional electrophoresis (2-DE), we previously showed that there are at least four variants of SCCA1 and three variants of SCCA2 in cervical squamous cell carcinoma tissues (16,17). Although 2-DE is a powerful tool for analyzing the molecular heterogeneity of proteins, this technique containing isoelectric focusing gel electrophoresis (IEF) is regarded as a complicated method.…”

SERPINB3 and B4: From biochemistry to biology

“…Although SERPINB3/B4 protease substrates characterized in the in vitro systems are also inhibited by SERPINB3/B4 in cultured cells [28, 29], the structures of the interacting complex have not been crystallized and the interaction and related enzymatic kinetics study remain to be carried out under in vivo conditions.…”

Deciphering the mystery of hepatitis B virus receptors: A historical perspective

“…Apoptosis may be attenuated by SCCA1 to regulate cell death/proliferation balance [44]. As SCCA1 is largely found in squamous cells, it is not restricted to hepatocytes present in all tissues of body.…”