Feb 1, 1993 - The pathogenesis of ovarian cancer and the factors leading to this disease are poorly understood. Although p53 gene alterations are common ...
Proc. Natl. Acad. Sci. USA Vol. 90, pp. 4961-4965, June 1993 Medical Sciences
p53 gene mutations and protein accumulation in human ovarian cancer JOLANTA KUPRYJA*CZYK*, ANN D. THOR*, ROBERTA BEAUCHAMPt, VICTOR MERRITTt, SUSAN M. EDGERTON*, DEBRA A. BELL*, AND DAVID W. YANDELLt,§ *Department of Pathology, Harvard Medical School, and the James Homer Wright Laboratories of Massachusetts General Hospital, Boston, MA 02114;
tDepartment of Cancer Biology, Harvard School of Public Health, Boston, MA 02115; and tMolecular Genetics Research Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA 02114
Communicated by Ruth Sager, February 1, 1993
ABSTRACT Mutations of the p53 gene on chromosome 17p are a common genetic change in the malignant progression of many cancers. We have analyzed 38 malignant tumors of ovarian or peritoneal mullerian type for evidence of p53 variations at either the DNA or protein levels. Genetic studies were based on single-strand conformation polymorphism analysis and DNA sequencing of exons 2 through 11 of the p53 gene; mutations were detected in 79% of the tumors. These data show a statistically significant association between mutations at C-G pairs and a history of estrogen therapy. Two of 20 patients whose normal tissue could be studied carried germ-line mutations of p53. Immunohistochemical analysis of the p53 protein was carried out using monoclonal antibody PAb1801. Ninetysix percent of the missense mutations were associated with abnormal accumulation of p53 protein, but nonsense mutations, a splicing mutation, and most deletions did not result in p53 protein accumulation. A statistically significant association between p53 protein accumulation in poorly differentiated stage Im serous carcinomas and small primary tumor size at diagnosis was found, perhaps suggesting that p53 protein accumulation accelerates the metastatic spread from a primary tumor. Overall, our findings indicate that alterations of p53 play a major role in ovarian cancer, including predisposition to the disease in some patients, and suggest a possible mechanism for somatic mutations leading to this cancer.
immunohistochemical analysis on all samples for accumulation of the p53 protein and compared all of these data to epidemiologic, clinical, and histologic findings. MATERIALS AND METHODS Patients and Clinical Samples. Tumor specimens were derived from 38 patients treated for ovarian cancer at the Massachusetts General Hospital between 1985 and 1991; ages of these patients ranged from 38 to 89 years. The specific tumor types studied are shown in Table 1. Tumor 21 (a mucinous adenocarcinoma) had a component of borderline malignancy (19). Two patients were diagnosed with synchronous endometrial cancers (patients 6 and 32). Most tissues studied were from the initial surgical resection (36 tumors); two samples involved only tumors that recurred after chemotherapy (samples 29 and 33). All tumors were staged according to the criteria of the International Federation of Gynecologists and Obstetricians (20) and graded 1 to 3 according to their nuclear features (21). Thirty-four tumors were in stage III or VI, 2 were in stage II (tumors 37 and 38), and two were in stage I (tumors 21 and 33). All tumors were poorly differentiated except for the two mucinous carcinomas that were moderately differentiated. Medical records of 36 patients were available for review, and 21 patients reported one or more close relatives with cancer. Thirteen patients had one or more family members affected by ovarian cancer, breast cancer, or multiple primary cancers. Four patients in this study had been treated previously for cancer (patient 9, squamous cell carcinoma of the vulva; patients 10 and 24, basal cell carcinoma of the skin; patient 27, independent breast and colon carcinomas). Data on other risk factors were also gathered, including: gravidity and parity (8 nulliparous patients), peri- or postmenopausal estrogen therapy (6 patients; Table 1), morbid obesity (4 patients), positive smoking history (12 patients), and previous laparotomies (21 patients). The median follow-up time was 19 months for the group as a whole and 21 months for survivors. To compare primary tumor sizes with other criteria, the maximum tumor diameter involving the ovary was taken from the pathology reports. When bilateral ovarian tumors were present, the diameter of the larger tumor was used. For statistical analysis, three size groups of tumors were arbitrarily established that gave a roughly equal number of samples in each group: tumors c5 cm, >5 cm but
