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Updated: Jun 3, 2026
Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms
Published on: December 9, 2015
Genetic analysis of drug resistance by reverse in situ hybridization
1CRC Department of Medical Oncology, Beatson Laboratories, University of Glasgow, Glasgow, UK.
Abstract:
Drug resistance is a major factor that limits the effectiveness of cancer chemotherapy, and there is considerable evidence to suggest a genetic basis for many drug-resistant phenotypes. A major drawback to many of the conventional approaches used to investigate drug-resistance mechanisms is that some prior information or guesswork on the changes that have occurred is required, thus necessitating separate reagents to screen each possible change. When analyzing genetic changes for example, screening is limited to the use of gene or region specific probes as in Southern blot or microsatellite analysis. Recently, the molecular cytogenetic techniques of reverse in situ hybridization (REVISH), and its more advanced relative, comparative genomic hybridization (CGH), have been developed for the rapid global detection and mapping of genetic imbalances in tumor genomes (1-7). In REVISH, genomic DNA from the tumor is used as a complex probe and hybridized to normal metaphase chromosomes (6). Genomic sequences amplified in the tumor are then detected as an increased intensity of signal at the normal chromosomal position from which the amplified sequences are derived (1,6,7). For more accurate analysis of both loss and gain of genetic material, CGH is required; however, CGH involves complex fluorescence-comparison techniques and expert knowledge of chromosome identification (2). However, both REVISH and CGH are ideal methods to detect genetic changes associated with the acquisition of drug resistance in tumors (6,8).
Insights
Drug resistance in cancer chemotherapy is often genetic. New molecular cytogenetic techniques like reverse in situ hybridization (REVISH) and comparative genomic hybridization (CGH) rapidly detect genetic imbalances in tumors, aiding resistance mechanism studies.
Area of Science:
- Cancer Research
- Molecular Cytogenetics
- Genomics
Background:
- Drug resistance significantly limits cancer chemotherapy effectiveness.
- Genetic factors underlie many drug-resistant phenotypes.
- Conventional methods for studying drug resistance require prior knowledge and specific reagents, limiting comprehensive analysis.
Purpose of the Study:
- To introduce and highlight the utility of molecular cytogenetic techniques for detecting genetic changes associated with cancer drug resistance.
- To address the limitations of traditional methods in identifying genetic alterations driving drug resistance.
Main Methods:
- Utilized reverse in situ hybridization (REVISH) to hybridize tumor genomic DNA to normal metaphase chromosomes.
- Described comparative genomic hybridization (CGH) as a more advanced technique for analyzing both gains and losses of genetic material.
- Emphasized the global detection and mapping of genetic imbalances in tumor genomes.
Main Results:
- REVISH detects amplified genomic sequences in tumors as increased signal intensity on normal chromosomes.
- CGH provides more accurate analysis of both genetic loss and gain.
- Both REVISH and CGH are effective for identifying genetic changes linked to acquired drug resistance.
Conclusions:
- REVISH and CGH offer rapid, global detection of genetic imbalances in tumors.
- These techniques overcome limitations of conventional methods by not requiring prior assumptions about genetic changes.
- REVISH and CGH are valuable tools for investigating the genetic basis of cancer drug resistance.
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