1-Butanol extraction and subsequent reconstitution of membrane components which mediate metastatic phenotype.

Abstract

The purpose of this study was to examine the effect of noncytolytic 1-butanol extraction of cell membrane components upon the metastatic potential of i.v. injected neoplastic cells. Butanol extraction consistently increased the number of pulmonary, but not extrapulmonary, lesions observed following challenge of ( a ) C3H/HeJ mice with the chemically induced fibrosarcoma MCA-F or ( b ) C57BL/6J mice with the spontaneous melanoma B16. Variants of these cell lines which display either a low (MCA-F parental and B16-F1) or a high (MCA-F 9.4 and B16-F10) proclivity to induce pulmonary metastases were all affected by pretreatment with butanol. Organ distribution studies using 5-[125I]iododeoxyuridine-labeled B16-F10 cells demonstrated that significantly more butanol-extracted cells were initially arrested in the lungs but that the number of extracted and control cells in the pulmonary bed equalized over the first 3 hr. During the next 7 days, butanol-extracted cells were preferentially retained in the lungs, resulting in a 3- to 4-fold increase in the number of macroscopic pulmonary foci observed 3 weeks later. The enhanced initial arrest of extracted cells was not mediated by increased tumor cell homoaggregation or by tumor cell:lymphocyte heteroaggregation, nor did butanol extraction select cells with an intrinsically greater metastatic potential. However, the preferential survival of extracted cells may result from an increased resistance to natural cell-mediated cytotoxicity, since ( a ) pretreatment of hosts with a copolymer of polyinosinic and polycytidylic acids prior to challenge with extracted cells profoundly decreased the number of lung colonies, and ( b ) butanol extraction of YAC-1 lymphoma target cells decreased the ability of C57BL/6J splenocytes to effect natural cell-mediated cytotoxicity in an in vitro 51Cr release assay. Finally, reassociation of the extracted moieties with the membranes of butanol-extracted cells resulted in the reconstitution of the original metastatic phenotype. These results suggest that cell surface structures which mediate the successful establishment of pulmonary metastases are reversibly released by brief incubation of cells in aqueous solutions of 1-butanol.