Comparative genomic in situ hybridization discloses chromosomal copy number changes in a transplanted brain tumor line of the rat (Rattus norvegicus)

Abstract

We investigated chromosomal copy number changes in ethylnitrosourea-induced and serially transplanted gliomas of the rat by flow cytometry and Comparative Genomic in situ Hybridization (CGH). CGH analysis of a primary and four transplanted tumors revealed several genomic aberrations, including whole chromosome and subchromosomal gains and losses. Gains involved rat Chromosomes (RNO) 2, 3, 4, 5, 7, 9, 11, 12, 13, and Y, whereas losses affected RNO5, 13, 20, and Y. The primary tumor exhibited gain of RNO2q31qter and gain of RNO4. While gain of RNO2 was seen in nearly all investigated passages, gain of RNO4 was apparent in the primary tumor and in passage 2 and 5 tumors. Chromosomal alterations detected as single events were restricted to the transplanted tumors and included gain of RNO3q11, 3q41qter, 5q36, 7q34qter, 9q37, 11q, and Y, and loss of RNO5, 13, and 20q. Flow cytometry disclosed different aneuploid cell clones in the tumors investigated. The results are discussed in analogy to findings in human glial tumors.

The <i>p16/Cdkn2a/Ink4a</i> Gene Is Frequently Deleted in Nitrosourea-Induced Rat Glial Tumors

“…The cell lines RG2, F98 and 9L were derived from Fischer 344 rats, RGL.3 from BD-IX rats, and C6 cells were derived from randomly outbred rats [11]. In addition, the RFK1 rat fibroblast cell line [12] derived from a Fisher 344 rat served as a control. All cell lines were grown under standard cell culture conditions (37°C, 5% CO 2 ) in Dulbecco's modified Eagle's medium supplemented with 10% fetal calf serum, penicillin, streptomycin and glutamine.…”

Comparative genomic in situ hybridization discloses recurrent gain of chromosome 4 in experimental gliomas of the rat

“…Tumor T184 was classified as isomorphic mixed glioma, T693 and T17 as polymorphic mixed gliomas and T312 as polymorphic mixed glioma with endothelial proliferation and necrosis (not shown). Tumor T140 had been described earlier (Kappler et al, 1998).…”

“…A PAS III flow cytometer equipped with a long life 100 W mercury arc bulb (Partec) was used to estimate the cellular DNA content (DAPI fluorescence) of 10,000 cells. Nuclei obtained from normal rat liver tissue were used for standardization of the flow cytometer (see Kappler et al, 1998). The various cell populations in normal tissue and tumors and their DNA indices were determined from the collected FCM data using the multicycle program (Phoenix Flow System).…”

“…Comparative Genomic in situ Hybridization (CGH) provides a powerful tool to screen entire genomes for subchromosomal copy number changes (Kallioniemi et al, 1992;du Manoir et al, 1993) and has significantly contributed to the detection of genomic alterations in human and experimental brain tumors (e.g., Schröck et al, 1994;Schlegel et al, 1996;Weber et al, 1996;Kappler et al, 1998). Here we report on the investigation of five ENU induced gliomas of the rat by CGH which revealed a number of chromosome alterations among which the recurrent gain of RNO 4 suggests a contribution of this alteration to rat glial tumorigenesis.…”

“…The genetic characterization of experimental tumors is essential in order to evaluate their relevance as appropriate animal models for human neoplasms. We have used flow cytometry and a recently established Comparative Genomic in situ Hybridization (CGH) protocol for the rat (Kappler et al, 1998) to investigate chromosome copy number changes in five ethylnitrosourea induced gliomas of the rat. Flow cytometry showed aneuploid DNA indices in three of the tumors investigated.…”