Genetics of cell-surface antigens: Regional mapping of three components of the human cell-surface antigen complex, Al, on chromosome 11

AbstractIt has been challenging to identify tumor-specific cell surface antigens as the vast majority of tumor-associated antigens are also expressed by some normal tissues. In the course of our study on mesothelioma, we identified a highly specific tumor cell surface antigen that can be targeted for therapy development. Mesothelioma is caused by malignant transformation of the mesothelium, incurable and categorized into three histological subtypes, epithelioid, biphasic and sarcomatoid. To identity novel mesothelioma cell surface antigens with broad subtype coverage and high tissue specificity, we have previously selected phage antibody display libraries on live mesothelioma cells and tissues following counter-selection on normal cells, and identified a panel of human antibodies that bind all subtypes of mesothelioma but not normal mesothelium. One of the antibodies, M25, showed high specificity, and we hereby report the identification of the M25 antigen as ALPPL2. We performed immunohistochemistry on normal human tissues and found that ALPPL2 is expressed only on placental trophoblasts but not any other normal tissues. This exquisite tissue specificity and broad tumor type coverage suggests that ALPPL2 could be an excellent cell surface target for therapeutic development against mesothelioma. To evaluate therapeutic potential of ALPPL2 targeting, we developed an ALPPL2-targeted antibody-drug conjugate and demonstrated potent and specific tumor killing in vitro and in vivo against both epithelioid and sarcomatoid mesothelioma. Thus ALPPL2 belongs to a rare class of cell surface antigens that can be said as being truly tumor specific and is well suited for therapy development against ALPPL2 expressing tumors.

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A cell surface antigen of the mouse related to xenotropic MuLv defined by naturally occurring antibody and monoclonal antibody. Relation to Gix G(rada1), G(aksl2) systems of MuLV-related antigens.

Journal of Experimental Medicine ◽

10.1084/jem.154.3.659 ◽

1981 ◽

Vol 154 (3) ◽

pp. 659-675 ◽

Cited By ~ 14

Author(s):

Y Obata ◽

E Stockert ◽

A B DeLeo ◽

P V O'Donnell ◽

H W Snyder ◽

...

Keyword(s):

Monoclonal Antibody ◽

Cell Surface ◽

Surface Antigen ◽

Biochemical Characterization ◽

Surface Antigens ◽

Lymphoid Cells ◽

Cell Surface Antigen ◽

Mouse Strains ◽

Cell Surface Antigens ◽

Naturally Occurring

A new cell surface antigen of the mouse related to xenotropic murine leukemia virus (MuLV) is described. The antigen, designated G(erld), is defined by cytotoxic tests with the B6-x-ray-induced ERLD and naturally occurring antibody. G(erld) is distinct from all previously defined cell surface antigens. Monoclonal antibody with the same specificity has been developed. Inbred mouse strains are classified as G(erld)+ or G(erld)- according to the presence of absence of the antigen on lymphoid cells. G(erld)+ strains differ with regard to quantitative expression of G(erld) on normal thymocytes. The emergence of G(erld)+ tumors in G(erld)- strains indicates the presence of genes coding for the antigen even in strains not normally expressing the antigen. G(erld) has the characteristic of a differentiation antigen in normal mice. In G(erld)+ strains, high levels of the antigen are found on thymocytes with lower levels being detected on cells of spleen, lymph nodes and bone marrow. No G(erld) was detected in brain or kidney or on erythrocytes. The segregation ratios for G(erld) expression on thymocytes in backcross and F2 mice of crosses between G(erld)+ (B6, 129, and B6-Gix+) and G(erld)- (BALB/c) strains suggest that G(erld) expression is controlled by a single locus in B6, by two unlinked loci in 129, and by three unlinked loci in B6-Gix+ mice. Induction of the antigen by MuLV infection of permissive cells in vitro indicates that G(erld) is closely related to xenotropic and dualtropic MuLV; all xenotropic and dualtropic MuLV tested induced the antigen, whereas the majority of ecotropic and the two amphotropic MuLV failed to do so. As dualtropic MuLV are thought to be recombinants between ecotropic and xenotropic MuLV sequences, G(erld) coding by dualtropic MuLV may signify the contribution of the xenotropic part in the recombinational event. Serological and biochemical characterization indicates that G(erld) is related to the gp 70 component of the MuLV envelope. The relation of G(erld) to the previously defined gp 70-related cell surface antigens (Gix, G(rada), and G(aksl2) is discussed, particularly with regard to their characteristics as differentiation antigens, the genetic origin of dualtropic MuLV, and the leukemogenicity of MuLV.

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