Expression of Lewisa, sialyl Lewis3, Lewisx and sialyl Lewisx antigens
Tumour development is usually associated with changes in cell surface carbohydrates. The changes in cell surface carbohydrates can be classified into changes in the terminal carbohydrate structure, which include incomplete synthesis and modification of normally existing carbohydrates, and changes in the carbohydrate core structure. The backbone regions of the terminal structures are classically divided into one of two categories – type 1 chains and type 2 chains. In some solid tumours, incomplete synthesis of cell surface carbohydrates results in increased expression of the precursor structures of blood group A, B and H antigen (ABH) such as Lewis (Le)a, sialyl Lea, Lex and sialyl Lex. The blood group-related Lea and sialyl Lea antigens have type 1 terminal structures, and Lex and sialyl Lex antigens have type 2 terminal structures. The epitopes of the Lea and sialyl Lea antigens are isomeric to that of the Lex and sialyl Lex antigens, respectively. You can start online shopping right now – buy serevent inhaler for more advantages.
Determination of tumour-associated carbohydrate changes is used in the diagnosis of human cancer. Expression of particular carbohydrate structures is also associated with prognosis. Nakagoe et al and Nakamori et al reported that increased expression of sialyl Lex in colorectal carcinomas is correlated with poor prognosis. That is, it has been established that the level of sialyl Lex antigen expression in tumours is a useful prognostic variable in colorectal cancer patients. Recent studies indicate that sialyl Lex, sialyl Lea and related carbohydrate structures function as adhesion molecules and, theoretically, may be involved in tumour metastasis. Therefore, we expanded our study to elucidate whether the expression of their nonsialylated forms – Lex and its isomer Lea, and sialyl Lea antigen – is correlated with prognosis after surgery in colorectal cancer patients. The relations between the expression ofLea, sialyl Lea or Lex antigen in colorectal tumours and subsequent outcome remain unclear, although two studies demonstrated that sialyl Lea antigen expression is a prognostic factor in patients with advanced colorectal carcinoma.
An immunohistochemical study of Lea, sialyl Lea, Lex and sialyl Lex antigen expression was performed using the respective monoclonal antibodies in colorectal carcinoma tissues, and the prognostic value of the expression of these antigens was clarified by univariate and multivariate analyses.