Characterisation of transformed cell lines derived from irradiated human epithelial cells expressing telomerase.

A C Riches, PhD a C Peddie, PhD a P E Bryant, DSc a H Zitzelsberger, PhD b H Richter, PhD b J Smida, PhD b L Hieber, PhD b.

a Bute Medical Building, School of Biology, University of St. Andrews,Scotland and b Institute of Radiobiology, GSF-National Research Center for Environment and Health, Neuherberg, Germany.

AIM. The aim of the study is to compare the radiation-induced transformation responses of a human retinal pigment epithelial cell line (340RPE-T53 hTERT) immortalised with hTERT with the parent cell line from which it was derived. Cloned cell lines derived from the irradiated RPE hTERT cell line were characterised for tumourigenicity and molecular cytogenetic changes. METHODS. The cell lines were irradiated with fractionated doses of gamma irradiation and anchorage independent growth was evaluated. Colonies were isolated from agar and cloned cell lines established. These lines were characterised for tumourigenicity in athymic nude mice and for cytogenetic changes using CGH, SKY and FISH with breakpoint-specific YAC- and BAC-probes. RESULTS. Following fractionated doses of gamma irradiation, no anchorage independent colonies were observed in the parent RPE cell line. After similar dose regimens using the RPE hTERT cell line, anchorage independent colonies were observed and cloned cell lines established. These cell lines were tumourigenic in athymic nude mice. Several of the lines exhibited loss of one copy of chromosome 13 and CGH analysis revealed a high level amplification on 10p11.2. Using FISH with YAC- and BAC-probes and with gene-specific PCR products an atypical protein kinase C has been identified as the amplified gene. CONCLUSIONS. Differences in the radiation-induced transforming ability of the parent and the immortalised cell line were established. Characterisation of the radiation-induced transformed cloned cell lines demonstrated that they were tumourigenic and exhibited an amplification on chromosome 10p11.2 associated with an atypical protein kinase C.

KEY WORDS: Radiation-induced carcinogenesis, protein kinase C, human retinal pigemnt, cell line.

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Chromosomal Aberrations.