Advances in the Molecular Detection of ABC Transporters Involved in Multidrug Resistance in Cancer

Abstract

ATP-Binding Cassette (ABC) transporters are important mediators of multidrug resistance (MDR) in patients with cancer. Although their role in MDR has been extensively studied in vitro, their value in predicting response to chemotherapy has yet to be fully determined. Establishing a molecular diagnostic assay dedicated to the quantitation of ABC transporter genes is therefore critical to investigate their involvement in clinical MDR. In this article, we provide an overview of the methodologies that have been applied to analyze the mRNA expression levels of ABC transporters, by describing the technology, its pros and cons, and the experimental protocols that have been followed. We also discuss recent studies performed in our laboratory that assess the ability of the currently available high-throughput gene expression profiling platforms to discriminate between highly homologous genes. This work led to the conclusion that high-throughput TaqMan-based qRT-PCR platforms provide standardized clinical assays for the molecular detection of ABC transporters and other families of highly homologous MDR-linked genes encoding, for example, the uptake transporters (solute carriers-SLCs) and the phase I and II metabolism enzymes.

Cytotoxicity of synthesized 1,4-naphthoquinone analogues on selected human cancer cell lines

“…[19][20][21] Although major advances have been made by researchers but the medical need is still largely unmet due to many factors; among which are the lack of selectivity of conventional drugs leading to toxicity, the metastatic spreading, and multi -drug resistance. [22][23][24][25][26][27] Novel and selective anticancer agents are urgently required due to problems associated with currently available anticancer drugs. The plant Euclea natalensis (A.…”

Redefining the relevance of established cancer cell lines to the study of mechanisms of clinical anti-cancer drug resistance

“…This finding highlights a major drawback linked to the technological limitations of the platforms commonly used to determine gene expression profiles. These limitations include inadequate sensitivity of some assays, poor dynamic range, and lack of specificity of the probes, especially in studies investigating MDR mechanisms, because many of the mediators belong to highly homologous gene superfamilies (3,24).…”

The importance of drug transporters in human pluripotent stem cells and in early tissue differentiation

“…After this standardization, the involvement of specific biological mechanisms can be properly explored, even considering the potential cell line or culture condition differences . Several methods allow the detection of transporter mRNA expression levels including microarrays and quantitative real time PCR (qRT-PCR) measurements, as elegantly reviewed by Gillet et al [11]. These methods are especially relevant 140 when a wide range of transporter expression profile of the cells has to be examined, since detection of numerous human transporters at the protein level is hindered by the lack of reliable antibodies.…”

“…However, the sensitivity of these methods varies as the extensive comparison by Gillet and colleagues 145 showed. [11,12] While microarrays proved to be less adequate to discriminate between products of highly homologous genes, the Human ABC Transporter TaqMan Low-Density Array (TLDA) has been documented to be most sensitive and best suited for accurately quantitating individual ABC 150 transporter genes in a high-throughput format. [11,12] Therefore, when assessing the transporter profile of hPSCs and early derivatives, currently the TLDA should be the method of choice.…”

“…[11,12] While microarrays proved to be less adequate to discriminate between products of highly homologous genes, the Human ABC Transporter TaqMan Low-Density Array (TLDA) has been documented to be most sensitive and best suited for accurately quantitating individual ABC 150 transporter genes in a high-throughput format. [11,12] Therefore, when assessing the transporter profile of hPSCs and early derivatives, currently the TLDA should be the method of choice. [13] ABC transporter mRNA levels significantly change over 155 the course of hPSC differentiation [13,14]; therefore, parallel to the examination of transporter profiles, a pluripotency array analysis should also be performed to validate the pluripotent state of the hPSCs.…”