Brain glycoproteins and recognition functions: recognins and cancer

Anti-malignin Antibody Evaluation: A Possible Challenge for Cancer Management

The major problem in the management of cancer is the difficulty of an early diagnosis. Clinical signs and symptoms generally appear late in the course of the disease. The availability of a non-invasive test which detects a blood molecule closely associated with the malignant transformation of the cells could be of help in the early detection of cancer. Malignin is a 10 kDa polypeptide located in the cytoplasmic and outer membranes of all malignant cells. Anti-malignin antibodies (AMAs) are IgM immunoglobulins spontaneously produced by the host against the oncoprotein malignin when neoplastic transformation occurs; since AMAs are IgM, they can represent an “early” transformation indicator useful for the early detection of cancer. Elevated AMA serum concentrations, measured by means of TARGET®@ reagent, have been demonstrated inpatients with a wide spectrum of non-terminal active cancers, regardless of the anatomical site and histotype of the tumor. The AMA test showed a sensitivity and specificity of 95% on first determination and >99% on repeated determinations, and has been reported to be a promising diagnostic tool for the early detection of cancer, as well as for monitoring of the response to treatment and possibly for screening of an asymptomatic population.

Production of two recognins related to malignin: recognin M from mammary MCF-7 carcinoma cells and recognin L from lymphoma P3G cells

From the first two non-brain cancer cell types examined, mammary cancer cells (MCF-7) and lymphoma cells (P3G), two new acidic polypeptides of approximately 10,000 M.W. each have been produced, called recognin M and recognin L, respectively. These are very closely related in amino acid composition and in immunological reactions to the first two cancer recognins, astrocytin from human gliomas in vivo and malignin from malignant glial cells grown in vivo. Together with earlier findings, these observations suggest that the cancer polypeptide recognins may be produced from members of a closely related family of substances characteristic of malignant cells.