Molecular cytogenetic studies of a serially transplanted primary prostaticcarcinoma xenograft (CWR22) and four relapsed tumors

BACKGROUND. Established cell lines or xenografts from prostatic carcinoma h ave been infrequently studied cytogenetically. CWR22 and CWR22-R are xenogr afts that are unique in offering one strongly androgen-dependent and severa l relapsed strains of a human prostate cancer that can be investigated in t he laboratory. We report on the cytogenetic characterization of the hormone -dependent CWR22, and the relapsed CWR22-R serially transplanted xenografts , in our laboratory. METHODS. We utilized a suspension harvest of the xenograft tissue to optimi ze our yield for metaphase chromosome studies and analyzed the hormone-depe ndent CWR22 and four relapsed CWR22-R xenografts. These studies were accomp lished using standard G-banded analysis and fluorescence in situ hybridizat ion (FISH). A variety of DNA probes including oc-satellite DNA probes, and chromosomal libraries, were utilized for the FISH analysis. RESULTS. Utilizing both standard cytogenetic analysis and FISH studies we h ave more precisely defined the CWR22 xenograft: 49,XY,+i(1)(q10),-2,der(4)t (2;4)(p21;q33), +7,+8,+12[7]/50,XY,idem,+der(2)t(2;4) (p21;q33)del(2)(q13q3 3)[13]. Four relapsed xenografts, CWR22R-2152, CWR22R-2524, CWR22R-2274, an d CWR22R-2272 were also studied. Each of these lines demonstrated a differe nt karyotype. CONCLUSIONS. The CWR22 karyotype offers the simplest reported karyotype for a prostate cancer tissue culture cell line or xenograft; this makes CWR22 an attractive candidate for studies of genetic changes associated with the relapse of prostate cancer treated with androgen withdrawal. Four separate, serially transplanted, relapsed CWR22-R xenografts were detected, each wit h a separate karyotype. Prostate 41:7-11, 1999. (C) 1999 Wiley-Liss, Inc.