Description
Cancer cell lines have been shown to be reliable tools in genetic studies of breast cancer, and the characterization of these
lines indicates that they are good models for studying the biological mechanisms underlying this disease. Here, we describe
the molecular cytogenetic/genetic characterization of two sister rat mammary tumor cell lines, HH-16 cl.2/1 and HH-16.cl.4,
for the first time. Molecular cytogenetic analysis using rat and mouse chromosome paint probes and BAC/PAC clones
allowed the characterization of clonal chromosome rearrangements; moreover, this strategy assisted in revealing detected
breakpoint regions and complex chromosome rearrangements. This comprehensive cytogenetic analysis revealed an
increase in the number of copies of the Mycn and Erbb2 genes in the investigated cell lines. To analyze its possible
correlation with expression changes, relative RNA expression was assessed by real-time reverse transcription quantitative
PCR and RNA FISH. Erbb2 was found to be overexpressed in HH-16.cl.4, but not in the sister cell line HH-16 cl.2/1, even
though these lines share the same initial genetic environment. Moreover, the relative expression of Erbb2 decreased after
global genome demethylation in the HH-16.cl.4 cell line. As these cell lines are commercially available and have been used
in previous studies, the present detailed characterization improves their value as an in vitro cell model. We believe that the
development of appropriate in vitro cell models for breast cancer is of crucial importance for revealing the genetic and
cellular pathways underlying this neoplasy and for employing them as experimental tools to assist in the generation of new
biotherapies. FCT: Project POCI/BIA-BCM/58541/2004, PhD grant SFRH/BD/25813/2005 and ‘Sistema Científico e Tecnológico Nacional - Ciência 2007"