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Updated: Aug 9, 2026
Colorectal Cancer Cell Surface Protein Profiling Using an Antibody Microarray and Fluorescence Multiplexing
Published on: September 25, 2011
Molecular cloning and characterization of a human adenocarcinoma/epithelial cell surface antigen complementary DNA
J Strnad1, A E Hamilton, L S Beavers
1Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285.
Abstract:
A human adenocarcinoma-associated antigen (KSA) defined by the monoclonal antibody KS1/4 has become the focus of several site-directed strategies for tumor therapy. KSA, a 40,000 Da cell surface glycoprotein antigen, is found at a high density in all adenocarcinomas examined to date and in corresponding normal epithelial tissues. Here we describe the cloning and sequencing of overlapping complementary DNA clones which encode the entire KSA as expressed in UCLA-P3, a human lung adenocarcinoma cell line. We have deduced the 314-amino acid sequence and have compared it to the N-terminal amino acid sequence data of the affinity-purified antigen. The KSA is synthesized as a 314-residue-long preproprotein that is then processed to a 232-residue-long antigen. KSA appears to have a single transmembrane domain of 23 residues that separates the highly charged 26-residue cytoplasmic domain from the extracellular domain. The N-terminal region of the propeptide is rich in cysteines and contains three potential N-glycosylation sites. Computer-assisted analyses at both the DNA and protein levels have found no significant similarities of this protein to known sequences, but a GC-rich 5' terminus is evident. Northern blot analysis shows that transcription of KSA can be detected in RNA isolated from normal colon but not in RNA isolated from normal lung, prostate, or liver.
Insights
Researchers cloned and sequenced the human adenocarcinoma-associated antigen (KSA), a cell surface glycoprotein crucial for tumor therapy. This study reveals KSA
Area of Science:
- Molecular Biology
- Oncology
- Biochemistry
Background:
- The human adenocarcinoma-associated antigen (KSA), identified by monoclonal antibody KS1/4, is a target for cancer therapy.
- KSA is a 40,000 Da cell surface glycoprotein found in high abundance in adenocarcinomas and their corresponding normal tissues.
Purpose of the Study:
- To clone and sequence the complementary DNA (cDNA) encoding the KSA.
- To elucidate the full amino acid sequence and structural features of KSA.
- To investigate the transcriptional profile of KSA in various human tissues.
Main Methods:
- Cloning and sequencing of overlapping cDNA clones encoding KSA from a human lung adenocarcinoma cell line (UCLA-P3).
- Deduction of the 314-amino acid sequence and comparison with N-terminal data of the purified antigen.
- Northern blot analysis to detect KSA transcription in normal colon, lung, prostate, and liver tissues.
Main Results:
- The complete 314-amino acid sequence of KSA was determined, revealing a preproprotein processed to a 232-residue mature antigen.
- KSA possesses a single transmembrane domain, separating a charged cytoplasmic domain from the extracellular domain.
- The extracellular domain's N-terminal region is cysteine-rich with three potential N-glycosylation sites; no significant sequence homology was found.
- KSA transcription was detected in normal colon but not in normal lung, prostate, or liver.
Conclusions:
- The study provides the complete molecular characterization of KSA, including its deduced amino acid sequence and structural organization.
- The tissue-specific transcription pattern suggests KSA's potential as a targeted therapeutic agent for specific adenocarcinoma types.
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