Abstract
A new monoclonal antibody recognizing CEACAM6, which we named AP11, was generated by immunizing BALB/c mice with phytohemagglutinin-activated human peripheral blood mononuclear cells. This study aims to evaluate whether CEACAM6 can serve as a tumor marker using AP11. We examined the expression of CEACAM6 with AP11 in 11 human carcinoma cell lines by flow cytometry and 439 human tissues including 282 tumor tissues and 157 normal tissues by immunohistochemistry. CEACAM6 epitope recognized by AP11 was well preserved in formalin-fixed and paraffin-embedded tissues. Adenocarcinomas of the stomach (86 %), colorectum (95 %), pancreas (100 %), and lung (83 %), urinary bladder (100 %), and mucinous ovarian tumors (88 %) had a high rate of CEACAM6 immunoreactivity. We observed a variable expression of CEACAM6 in hepatocellular carcinomas (35 %), squamous cell carcinomas of the lung (60 %), renal cell carcinomas (14 %), urothelial carcinomas (13 %), serous carcinomas of the ovary (17 %), and breast carcinomas (11 %). Small-cell carcinomas of the lung, prostatic adenocarcinomas, papillary thyroid carcinomas, malignant melanomas, giant cell tumors, and osteosarcomas were negative for CEACAM6. All normal tissues of various organs were negative for CEACAM6. In conclusion, CEACAM6 as detected by AP11, may serve as a marker for mucin-producing adenocarcinomas of the gastrointestinal tract and ovary as well as non-small cell lung cancer. Thus, AP11 represents a valuable diagnostic tool for detecting CEACMA6-positive cancers.
Highlights
The carcinoembryonic antigen (CEA) gene family belongs to the immunoglobulin superfamily [1] and comprises of 29 genes that are located closely together on the long arm of chromosome 19 [2]
CEA is overexpressed in a majority of carcinomas, including those of the gastrointestinal, respiratory, and genitourinary tracts as well as in breast cancers, it is expressed in normal adult tissue [4]
When the peripheral blood cells were analyzed by flow cytometry using AP11, granulocytes exhibited a high level of reactivity to AP11, indicating the expression of AP11 antigen, whereas lymphocytes and monocytes were negative for AP11
Summary
The carcinoembryonic antigen (CEA) gene family belongs to the immunoglobulin superfamily [1] and comprises of 29 genes that are located closely together on the long arm of chromosome 19 [2]. CEA (CD66e and CEACAM5) is a complex, highly glycosylated macromolecule. It was first described in 1965 as a gastrointestinal oncofetal protein that is expressed during fetal life but not in healthy adults, re-emerging in cancer [3]. CEA is overexpressed in a majority of carcinomas, including those of the gastrointestinal, respiratory, and genitourinary tracts as well as in breast cancers, it is expressed in normal adult tissue [4]. Among the main proteins of the CEA family, CEA is the only one that has been characterized as a useful tumor marker in cancer patients. Increased CEA levels are the first indicator of recurrent disease [5, 6], and serum CEA levels are used as a prognostic indicator in colorectal cancer patients
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