title: Variations in DNA aneuploid cell content during tumor dissociation in human colon and head and neck cancers analyzed by flow cytometry.
abstract: Experimental research involving human solid tumors often requires single cell suspensions of high yield that are representative of the tissue of origin and in which the cellular property of interest is preserved. This is particularly necessary for the determination of DNA ploidy by flow cytometry. Mechanical dissaggregation and proteolytic enzyme digestion are the most commonly employed dissociation techniques for solid tumors. Comparative testing of techniques is often not performed. Mechanical and proteolytic enzyme dissociation techniques were comparatively tested in 77 human squamous cell cancers of the head and neck (SCCHN) and 25 human colon cancers for cellular yield, dye exclusion viability, quality, and morphology of DNA histograms, and the presence and proportion of DNA aneuploid subpopulations. Significant and consistent DNA aneuploid subpopulation losses were noted in mechanical preparations of SCCHN and enzymatic preparations of colon cancers. The frequency of SCCHN specimens with DNA aneuploid subpopulations was underestimated by 52% in mechanical cell suspensions, and the proportion of DNA aneuploid cells was diminished in an additional 30% of the specimens. Conversely, the frequency of specimens with DNA aneuploid subpopulations was underestimated by 38% in cell suspensions from enzymatically dissociated human colon cancer and their proportion diminished in an additional 50% of the specimens. Incubations of human colon cancers with three commonly employed proteolytic enzymes demonstrated a progressive loss of DNA aneuploid subpopulations as a function of enzyme concentration and incubation time. This is a serious potential source of error in the flow cytometric determination of DNA ploidy in human solid tumors, and may contribute to the diversity of results obtained and occasional contradictory conclusions reached in such studies.
authors.affiliation: Department of Internal Medicine, School of Medicine, Wayne State University, Detroit, Michigan 48201.
authors.forename: J F
authors.initials: JF
authors.lastname: Ensley
authors.forename: Z
authors.initials: Z
authors.lastname: Maciorowski
authors.forename: M
authors.initials: M
authors.lastname: Hassan
authors.forename: H
authors.initials: H
authors.lastname: Pietraszkiewicz
authors.forename: W
authors.initials: W
authors.lastname: Sakr
authors.forename: L K
authors.initials: LK
authors.lastname: Heilbrun
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000782:Aneuploidy; D017364:Collagenases / Q000494:pharmacology; D003110:Colonic Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000473:pathology; D004273:DNA, Neoplasm / Q000032:analysis* / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006258:Head and Neck Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors
chemical_list: D004273:DNA, Neoplasm; D017364:Collagenases