Cervical brush biopsy specimens suitable for DNA and oncoprotein analysis using flow cytometry

Papillomavirus and c-myc antigen expression in normal and neoplastic cervical epithelium

Cervical punch biopsy specimens or brushings were collected from 33 patients with cervical human papilloma virus (HPV) infection, cervical intraepithelial neoplasia (CIN), or invasive cervical carcinoma, and from eight control patients with recent normal cervical cytology. Prostatic chippings obtained from six men with benign prostatic hypertrophy were used as further controls. Biopsy specimens and brushings were assayed by flow cytometry for c-myc oncogene antigen and papillomavirus antigen expression and rate of cell division (by measuring DNA content). Results obtained from analysis of specimens and brushings were similar in terms of c-myc antigen and total DNA content, but when the percentages of nuclei from biopsy and brush specimens staining positively with antibody to papilloma viral antigens were compared, brush specimens gave consistently higher percentages than biopsy specimens. More specimens from normal epithelium were c-myc antigen positive (five of eight, (63%) than specimens from CIN II or III (two of 10, 20%), or invasive carcinoma (0%). No association was found between c-myc antigen expression and cell division. HPV antigen positive specimens were found to contain more dividing cells than negative specimens.

Nuclear c-myc protein, maturation, and cell-cycle status of human haemopoietic cells

Human c-myc protein, p62c-myc, has been quantitated by flow cytometry in the nuclei of normal marrow and peripheral blood cells, and the HL60 cell line. Marrow and peripheral blood cells exhibit nuclear c-myc protein throughout the cell-cycle, at an average level 2-3-fold lower than HL60 cells. In no cells did p62c-myc vary more than 2-fold throughout the cell cycle. A small subset of marrow G0/G1 cells, enriched in early myeloid and blast cell fractions, contained p62c-myc at levels equal to or even exceeding those of HL60. Overall c-myc protein content was higher in myeloid, compared to erythroid and lymphoid marrow fractions. Within the myeloid lineage, the highest average p62c-myc level was present in cells of intermediate maturation, i.e. myelocytes and metamyelocytes. In the erythroid lineage, c-myc protein level was highest in the most immature cells and declined with maturation. Significant amounts of p62c-myc were present in post-mitotic, end-stage neutrophils, but were barely detectable in cycling late erythroblasts or in quiescent lymphocytes and monocytes. HL60 cells, despite c-myc gene amplification and increased gene expression, contain c-myc protein at a level corresponding to promyelocytes in normal human marrow. The virtual absence of p62c-myc in cycling late erythroblasts, and its presence in post-mitotic end-stage granulocytes, suggests that c-myc protein may have functions unrelated to cell proliferation.

Abnormal distribution of c-myc oncogene product in familial adenomatous polyposis

Monoclonal antibodies raised by synthetic peptide immunisation were used to determine the distribution of the protein product of the c-myc gene by immunocytochemical staining of archival wax embedded material from patients with familial adenomatous polyposis. Polyps from 18 cases of familial adenomatous polyposis, 10 of whom had developed malignant change, and 30 normal control colonic biopsy specimens were examined. A consistent staining pattern was observed in normal mucosa; nuclear staining in the basal proliferative zone; mixed nuclear and cytoplasmic staining in the maturation zone; and cytoplasmic localisation in the surface mature zone. In contrast, the polyps and carcinomata showed a mixed pattern of cytoplasmic and nuclear localisation in the basal proliferative zone with nuclear persistence throughout the crypts to the surface mature zone. This abnormal distribution of the c-myc oncogene product may have a role in the evolution of polyps and their subsequent malignant transformation into familial adenomatous polyposis.

Oncogene expression in ovarian cancer: a pilot study of c-myc oncoprotein in serous papillary ovarian cancer

The nuclear-associated protein product of the c-myc gene, p62c-myc, was assayed simultaneously with total DNA using flow cytometry in nuclei extracted from archival biopsies of serous papillary carcinoma of the ovary. The oncoprotein was probed with a synthetic peptide-induced mouse monoclonal antibody which was subsequently labeled with a fluorescent rabbit anti-mouse immunoglobulin and DNA was assayed using the nucleic acid fluorochrome propidium iodide. Serous papillary ovarian carcinoma expressed significantly higher p62c-myc levels compared with normal ovary (P less than 0.00003 Mann-Whitney U test). Biopsies classified as "borderline" low-potential malignancy exhibited levels between normal ovary and carcinoma. The difference between normal and "borderline" was significant at P less than 0.003, but no difference between "borderline" and frankly invasive biopsies was observed, P = 0.149. There was no difference among the histological grades of carcinomas. All normal ovaries had diploid DNA content as did 5/6 cases of "borderline" malignancy. The majority of cases of carcinoma, 28/36, were aneuploid. There was a statistically significant difference in the distribution of aneuploidy, P less than 0.005, between invasive carcinomas and those classified as "borderline" low-potential malignancy.

Flow cytometric quantitation of the c-myc oncoprotein in archival neoplastic biopsies of the colon

The c-myc oncogene encoded protein product, p62c-myc, was assayed simultaneously with DNA in populations of individual nuclei extracted from archival biopsies of colonic neoplasia. Both the protein and DNA were assayed fluorimetrically using flow cytometry with a synthetic peptide induced monoclonal antibody (MYC 1-6E10) for the protein and propidium iodide for DNA. The nuclear p62c-myc levels increased progressively from normal mucosa through polyps to carcinomas. However, there was a trend for the more poorly differentiated carcinomas to exhibit lower levels than moderately and well-differentiated tumours, p = 0.085. These results agree with those published previously with the same antibody using Western blotting for protein extracted from fresh frozen tissue and immunocytochemical assessment. Furthermore, flow cytometry is able to effect discriminations between subsets in heterogeneous populations using DNA as a second parameter which Western blot bulk studies cannot.

Flow cytometric quantitation of DNA and c-myc oncoprotein in archival biopsies of uterine cervix neoplasia

The c-myc nuclear associated oncoprotein has been quantitated simultaneously with DNA in nuclei extracted from archival biopsies of uterine cervix neoplasia. The oncoprotein and DNA were measured fluorimetrically in a flow cytometer using a mouse monoclonal antibody (MYC 1-6E10) and propidium iodide. Normal biopsies exhibited higher oncoprotein levels than carcinomas (P less than 0.00001). Furthermore, the maximum fluorescence signal in the normal tissue occurred at a lower antibody concentration compared with tumour tissue. There was no correlation between oncoprotein levels and histological grade, stage of disease, age of the patients or prognosis in the carcinomas. Aneuploidy, defined as a distinct second peak separate from the diploid distribution, was not a significant feature. The c-myc oncoprotein nuclear content does not appear to be a prognostic indicator in carcinoma of the cervix from the results of these studies but there is clearly diagnostic potential, particularly for automated analysis of cervical screening.