Chromosome Instability in Lymphocytes from Patients Affected by or Genetically Predisposed to Colorectal Cancer Florence Richard, Martine Muleris, and Bernard Dutrillaux ABSTRACT: To determine whether there are chromosomal clues to inherited forms of colorecta/cancer, we studied chromosome instability in lymphocytes cultured from persons with sporadic colorectal cancer before treatment and from persons with a genetic predisposition to colorectal cancer due to adenomatous polyposis coli, Peutz-]eghers syndrome, or juvenile polyposis. Spontaneous aberrations of chromosome number and structure were scored and compared to control studies by the same methods. Sex chromo- some aneuploidy was found increased in patients. Autosomal aneuploidy was not increased. Chromo- some breakage was elevated in young persons genetically predisposed to colorectal cancer compared to young patients with sporadic colorectal cancer. Chromosome rearrangements, other than those of chro- mosomes 7 and/or I4, rose with age, particularly in patients. Despite considerable interindividual varia- tions, it would seem that increased chromosome breakage and rearrangement in addition to sex chromo- some aneuploidy may be signs of chromosome instability in the predisposition to colorectal cancer. INTRODUCTION Among patients with colorectal carcinoma, about 5% may be hereditarily predisposed. Predisposition syndromes com- prise familial adenomatous polyposis (FAP), Peutz-]eghers syndrome, juvenile polyposi6, and hereditary nonpolypo- sis colon cancer (HI~rPCC). The APC gene, responsible for FAP, was assigned to chromosome 5 by cytogenetic and link- age analyses, and further cloned [1-4]. It is distinct from the I-INf~C gene, recently mapped on chromosome 2 [5, 6]. The genetic determinism for other predispositions remains un- known and, in the absence of complete information on the genes involved, it is of interest to search for other criteria to detect individuals at risk for inherited and noninherited forms of colorectal cancer. One criterion may be genomic in- stability. Such instability can be detected at both the molecular and chromosomal l~-els by either a high rate of spontaneous al- terations or an increased sensitivity to mutagenic or clasto- genic agents [7-14]. This study was developed on untreated patients affected by either a sporadic color~al cancer (SCRC) or FAP, l~utz leghers (P/] and juvenile polyposi6 (JP]. Spon- taneons chromosome aberretions were studied on blood lym- phocytes and compared to those found in controls of vari- ous ages. From CNRS URA 620, Institut Cur/e, Section de Biologie, Paris, France. Address reprint requests to: F. Richard, CNRS URA 620, lnstitut Cur/e-Section de Biologie, 26, rue dIJlm, 75231 Paris Cedex 05, France. Received May 24, 1993; accepted September 29, 1993. © 1994 Elsevier Science Inc. 655 Avenue of the Americas, New York, NrY 10010 MATERIALS AND METHODS Whole blood was cultured after PHA stimulation in TC199 supplemented with 20% human serum and heparin (10 IU/ml). Metaphases were harvested after a 2-h colchicine block, and 72-h cultures. All metaphases were R-banded, ana- lyzed on photographs, and karyotyped when a chromosome rearrangement was suspected. Aneuploidies and chromo- some breaks and rearrangements were scored, using the clas- sification proposed for acquired chromosome anomalies [15]. For each control, at least 1000 metaphases were studied [16- 18]. For each patient, except one young SCRC patient, at least 100 metaphases were studied using the same methods. Control Data The results on controls were obtained several years ago when it was decided to get information on a verylarge number of karyetypes (above 1000 per individual). With such large num- bers, no interindividual variations were observed within a given class of age, and a small number of cases were stud- ied. The data reported in Marlhens et al. [16], Prieur et al. [17], and Richard et al. [18] are now used as standards in the laboratory, where identical dulture conditions and chromo- some analysis conditions are kept. Patients SCRC: Fifteen patients (nine female and six male) whose ages ranged from 20 to 79 years. One patient had a fra(10](q24.2). FAP: Nine patients (seven female and two male) whose ages ranged from 15 to 56 years. One patient (55-year-old fe- male) had developed a colorectal cancer. A second one had 23 C~ncer Genet Cytogenet 73:23-32 (1994) 0165-4608/94/$07.00