Defining the Sister Rat Mammary Tumor Cell Lines HH-16 cl.2/1 and HH-16.cl.4 as an In Vitro Cell Model for Erbb2

Abstract

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.

The Importance of Cancer Cell Lines as in vitro Models in Cancer Methylome Analysis and Anticancer Drugs Testing

“…Cancer is a molecularly heterogeneous disease [1] and one of the major causes of death worldwide. The existence of various types of tumours with different histopathologies, genetic and epigenetic variations, and clinical outcomes [2], difficult the understanding of this disease, the mechanisms of action of chemotherapeutics and the creation of novel therapies.…”

“…Studies of cancer rely on the use of primary tumours [1,3], paraffin-embedded samples [1], cancer cell lines [1,3,4], xenografts [2,5,6], tumour primary cell cultures [3,4] and/or genetically engineered mice [2]. Each of these diverse models are used for different studies, mainly because certain types of manipulations for the genetic and DNA methylation analysis and drug testing are ethically, and in practice, difficult to perform in animals.…”

“…Nevertheless, a detailed characterization is fundamental before its use. This characterization provides important insights about the complexity of the polygenetic etiology of cancer and the biological mechanisms involved in this disease [1] reinforcing its value as models for its study [1,7]. Also the characterization of cancer cell lines is essential for the development of new anticancer drugs, understanding the action mechanisms and the resistance/sensitivity patterns of chemotherapeutics already in use in cancer treatment and the development of more targeted anticancer drugs.…”

“…This is an important and, in some cases an exclusive characteristic of this model [8]. Cell lines can be genetically/epigenetically manipulated using demethylation agents [1,19], siRNA [20], expression vectors [10] and pharmacologically manipulated using cytostatics [13]. -High homogeneity [2][3][4].…”

An overview on potential of in vitro studies and transcriptomics for cancer

“…Till date studies of cancer rely on the use of primary tumors, paraffin-embedded samples ,cancer cell lines [25][26][27], xenografts [28][29][30], tumor primary cell cultures [26,27] and/or genetically engineered mice [28]. Cancer cell lines are explored to investigate it's response to adverse environmental conditions [31,32], genetic perturbations [33] etc.…”