Clinical, pathological and genetic features of women at high familial risk of breast cancer undergoing prophylactic mastectomy

Prophylactic mastectomy (PM) is a risk-management option for women at high familial risk of breast cancer (BC). This study describes the PM experience of women enrolled in a large observational cohort study involving families with a history of hereditary breast cancer. Within 357 multiple-case BC families [119 (33%) BRCA1 or BRCA2 mutation positive], identified via family cancer clinics, 49 cases of PM [21 (43%) BRCA1 or BRCA2 mutation positive] were identified and their clinical, pathological and genetic features reviewed. Families with at least one incidence of PM displayed stronger breast/ovarian cancer histories than did families without PM. Median age at time of PM was 45 years (range 28-58). Ten cases (21%) were bilateral PMs in unaffected women and 39 cases were contralateral PMs in women with prior invasive BC (71%) or ductal carcinoma in situ (DCIS) (8%). Most (88%) underwent total mastectomy. Unnecessary axillary surgery occurred in eight subjects (16%). Malignant histology was found in three PM specimens (6%). Prior to genetic testing, PM was performed in two women who were subsequently shown not to carry the mutation specific to their family. Optimal utilization of genetic testing to guide surgical decision making, appropriate surgical technique and careful pathology examination of PM specimens, are important issues to consider prior to PM in women at high familial risk of BC.

Epidermal growth factor stimulates the synthesis of cell-attachment proteins in the human breast cancer cell line PMC42

The human breast cancer cell line PMC42 responds to the addition of epidermal growth factor (EGF) by proliferation and increased frequency of attachment of cell-organoid structures to the culture vessel. Antibodies to fibronectin and laminin reacted strongly, by immunoperoxidase, with the membranes of cells from organoids that became adherent following addition of EGF. This reaction was weak with membranes of cells of non-adherent organoids in cultures containing EGF and was negative with membranes of cells of free-floating organoids from cultures without EGF. An increase in biosynthetic labelling with 35S-methionine was found in cell lysates and supernatants of PMC42 cells cultured in the presence of EGF compared with control cells grown without EGF. One-dimensional SDS-polyacrylamide gel electrophoresis and 2-dimensional NEPHGE-PAGE of labelled cell proteins showed increased synthesis of several cellular proteins and the appearance in EGF-treated cells of 2 proteins which were not detected in cells from control cultures lacking EGF. Immunoprecipitation experiments using antibodies to fibronectin and laminin with lysates of 35S-methionine labelled PMC42 cells cultured with EGF showed strong immunoprecipitation at Mr 200 and 400 with anti-laminin, and at Mr 200 and 96 with anti-fibronectin. These immunoprecipitates were blocked specifically by purified laminin or fibronectin, respectively. No immunoprecipitates were detected with these antibodies in lysates from cells grown without EGF. EGF thus stimulates increased adherence of cultured PMC42 cell-organoid structures together with increased membrane expression of the cell-adhesive proteins laminin and fibronectin. These effects may play a role in normal development and neoplastic behaviour of breast epithelia.

Biochemical characterization of the monoclonal antibody-defined ovarian carcinoma-associated antigen SGA

The molecular nature of SGA, the ovarian-carcinoma-associated antigen defined by the MAb OM-1, has been determined. The cell-surface form of the SGA molecule is a glycoprotein with p1 less than 4.2, which on PAGE analysis has an apparent MW of approximately 360 kDa. This was the only OM-1-reactive species found on the cell surface. The apparent MW was unaffected by reducing conditions. The predominant cytoplasmic form of SGA is a non-glycosylated 170-kDa molecule with p1 6.5. Pulse-chase experiments were complicated by the extremely slow rate of SGA synthesis. However, the data indicate that the SGA molecule is synthesized as a 190-kDa protein, cleaved to yield a 170-kDa non-glycosylated intracellular form which is slowly glycosylated to the 360-kDa cell-surface species. Western blotting experiments revealed the presence of the 360-kDa glycosylated molecule in human ovarian cell culture supernatants.

Monoclonal antibody CI-panHu defines a pan-human cell-surface antigen unique to higher primates

The murine monoclonal antibody CI-panHu reacts strongly with the cell surface of all human cells, including erythrocytes, tumour cells and HLA-A,B,C-negative cell lines. As such, this antibody defines the first pan-human cell-surface antigen reported. The antigenic determinant detected is associated with a protein doublet of 16,000 MW whose expression is restricted to cells from humans, apes and some species of Old World monkeys. Antibody reactivity is not diminished by routine fixation procedures, nor by paraffin-embedding, and the antigenic determinant is relatively protease-resistant. The use of this antibody as a positive control in immunoassays of human cells is discussed.

The sebaceous gland antigen defined by the OM-1 monoclonal antibody is expressed at high density on the surface of ovarian carcinoma cells

A monoclonal antibody, designated OM-1, was raised against ovarian serous papillary cystadenocarcinoma (stage IV) cells. This antibody was found to react strongly with primary and metastatic ovarian serous cystadenocarcinomas and endometrioid carcinomas but the antigen detected was either absent or at very low levels in ovarian mucinous adenocarcinomas, clear cell carcinomas, benign serous and mucinous cystadenomas and Brenner tumours. The OM-1 antibody gave no detectable reaction with 93 other human tumours, including examples of breast and colon adenocarcinomas. In normal tissues the OM-1 antibody reacted with normal sebaceous gland cells, lung type II pneumocytes and placental syncytial trophoblasts. In the normal ovary OM-1 reactivity was confined to extremely weak staining of the surface epithelium. No reaction with any other ovarian cell type could be detected. No evidence of reaction with other normal cell populations present in 24 adult and seven foetal tissues was found. The antigen detected is compared with other ovarian tumour-associated antigens. The OM-1 antibody is likely to prove of value in the detection and diagnosis of ovarian carcinoma.

Children's brain tumour cells produce RNA particles with incomplete retrovirus characteristics

Short-term cultures of cells from human rain tumours have been reported to synthesise RNA particles of density in the range characteristic of C type RNA retroviruses, with associated DNA polymerase activity. Fresh tumour cells obtained from 6 children with astrocytoma and 7 children with medulloblastoma, together with one sample of normal brain tissue and normal leukocytes from brain tumour patients were assayed by several characteristics for the primate retrovirus. 1 or 6 (17%) astrocytomas and 4 of 7 (57%) medulloblastomas released RNA particles which banded in sucrose gradients at a density of 1.16-1.18 g/cm3 together with a short segment of DNA, which was eliminated by prior ribonuclease treatment and two proteins of 28k and 16k daltons. These findings were compatible with the presence of a primate retrovirus. Immune coprecipitation of 125I-labelled proteins from the 1.16-1.18 g/cm3 gradient region failed to show any reactivity with antisera to p28 core antigens or the p70 reverse transcriptase antigens of simian sarcoma virus, baboon endogenous virus or Mason Pfizer virus. Assays for DNA polymerase activity in culture supernatant fluid showed only a low amount of activity with template preferences not characteristic of the retroviral reverse transcriptase enzyme.