Mitoxantrone resistance in a small cell lung cancer cell line is associated with ABCA2 upregulation

Abstract

The aim of this study was to find factors that could explain the accumulation difference of mitoxantrone in the BCRP1-negative GLC4-MITO cell line compared to GLC4. Comparative genomic hybridisation (CGH) was applied to determine chromosomal differences between GLC4 and GLC4-MITO. Comparative genomic hybridisation analysis revealed gain of 2q, 6p, 9q, 13q, 14q, 15q, 19q and Xp and loss of 1p, 2q, 3p, 3q, 4q, 6q, 8q, 11p, 16p, 17q, 18p, 20p and Xq. In the over-represented chromosomal areas, seven transporter genes were identified: ABCB6, ABCB2 (TAP1), ABCB3 (TAP2), ABCF1 (ABC50), ABCC10 (MRP7), ABCA2 (ABC2) and ABCC4 (MRP4). No RNA or protein upregulation was observed for ABCB6, ABCF1, ABCC10, ABCC4, ABCB2 and ABCB3, but an increased expression was detected for ABCA2 mRNA in GLC4-MITO. ABCA2 is known to be involved in resistance to estramustine. In the MTT assay, GLC4-MITO was two-fold resistant to estramustine compared to GLC4. Coincubation with estramustine and mitoxantrone increased mitoxantrone accumulation in GLC4-MITO, while this was not affected in GLC4. This suggests that estramustine is able to block mitoxantrone efflux in GLC4-MITO cells. These data reveal that cellular reduction of mitoxantrone in a mitoxantrone-resistant cell line is associated with overexpression of ABCA2.

Elevated Expression of Hypoxanthine Guanine Phosphoribosyltransferase within Malignant Tissue

“…Due to its housekeeping nature, HPRT is often utilized as a control for expressional studies and transcriptional analysis in a variety of research techniques (Boonstra et al, 2004;Carver et al, 2009;de Kok et al, 2005;Hillion et al, 2009;Liu, Chen, & Liu, 2005;Lukasiak et al, 2008;Morimoto-Tomita et al, 2005;Reijm et al, 2011). Yet, the literature is inconsistent when reporting HPRT expression levels within cancer.…”

ATP Binding Cassette transporters associated with chemoresistance: transcriptional profiling in extreme cohorts and their prognostic impact in a cohort of 281 acute myeloid leukemia patients

“…In addition to well known expected transporters (ABCB1 and ABCG2) ABCA2, a candidate regulator of neural transmembrane lipid transport, was relevant for drug resistance in AML and ALL, 15,27 and in a small cell lung cancer cell line resistant to mitoxantrone. 28,29 ABCG1 is actually, like ABCA2, a cholesterol transporter, but has not yet been demonstrated to be directly involved in resistance to chemotherapy. 30 Nevertheless, cholesterol alterations can influence other ABC proteins' localization and function, such as ABCB1, which might contribute to chemoresistance.…”

Use of arrays to investigate the contribution of ATP-binding cassette transporters to drug resistance in cancer chemotherapy and prediction of chemosensitivity

“…However, it is currently unknown if amplifications of other ABC transporter genes also cause their over-expression in the drug resistant cells. Such a potential problem was better addressed in another similar study by Boonstra et al who also used the similar subtractive comparative genomic hybridization to analyze a mitoxantrone resistant small cell lung cancer cell line GLC4-MITO [42]. Of the 7 amplified ABC transporter genes (ABCA2, ABCB2, ABCB3, ABCB6, ABCC4, ABCC10 and ABCF1) detected using comparative genomic hybridization, only ABCA2 was found to show corresponding over-expression at RNA and protein levels, and its over-expression likely causes mitoxantrone resistance (Table 4).…”