Tumorigenic human squamous lung cancer cells have defined cell surface carbohydrates that are absent from nontumorigenic cells.

Cells of cloned lines derived from human squamous lung carcinomas spontaneously become heterogeneous with respect to several tumor-associated cell surface carbohydrates such as the sialosyl-Lea oligosaccharide antigen or the recently described oligosaccharide recognized by monoclonal antibody 43-9F. Subclones derived from these cultures are initially homogeneous with respect to the presence or absence of a specific cell surface carbohydrate but gradually revert back to a heterogeneous population. Cells of homogeneous subclones having both the sialosyl-LEa and 43-9F cell surface antigens and other subclones lacking them were injected subcutaneously in nude mice. All clones expressing these tumor-associated cell surface carbohydrates were found to be highly tumorigenic, whereas those lacking them were nontumorigenic or, at most, weakly tumorigenic. Clones having the tumor-associated cell surface carbohydrates were more resistant to cytotoxic attack by purified mouse natural killer cells than those clones lacking these carbohydrates, suggesting that the tumorigenicity of the former clones may be influenced by immunoprotective effects of these novel carbohydrates.