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Global Translational Medicine Role of HTS in cancer therapeutics

can generate a spectrum of other potential associated anthracyclines, methotrexate, and topoisomerase inhibitors,
targets. This process is termed as “target deconvolution” that to induce cell death. 108,109 In 2009, Ji et al. developed a DNA
arises due to possible interaction of small molecules with repair pathways-deficient chicken DT40 cell lines for high-
multiple cellular and/or extracellular targets or non-protein throughput genotoxicity screening that have effective gene
targets. 91,92 However, target deconvolution is not a primary targets, stable phenotype, and karyotype and are easy to
condition or demand for passing any candidate drug from maintain in suspension culture. 110-113 However, there are
phenotypic screens into late-stage preclinical or even several other phenotypic assays for screening out genotoxic
clinical development. 93-95 Advances in the field of chemical compounds, including GreenScreen HC GADD45a‑green
proteomics, coupled with in silico approaches and genome fluorescent protein (GFP) (BlueScreen HC, CellCiphr p53,
sequencing, have greatly improved our ability to determine and CellSensor p53‑bla). 114-116 These systems utilize p53
protein targets and underlying hits from phenotypic or DNA damage-associated genes due to their role in a
screens. 96-98 On one hand, a single-target-based approach is genotoxic stress causing the arrest of cell cycle at the G1/S
more useful to understand MOA of the drug and bridge the phase until repair is effective. Gentronix ‘GreenScreen HC’
link between modulation of target through a MOA, while assay utilizes the fact of genotoxin-induced transcription of
on the other hand, it could lead to off-target drug activity GADD45a (growth arrest and DNA damage) gene in human
and toxicity and suggest the need of multi-target therapies lymphoblastoid TK6, a karyotypically stable cell line. This
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to address complex multifactorial disease mechanisms. 99,100 assay measures the cell’s response to genotoxic stress, which
The second major challenge to phenotypic screening is linked to the GFP reporter with p53 regulatory elements
is metagenes influencing multiple signaling pathways. that ensure specific and dose-dependent response from
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Genome-wide gene expression profiling measures gene the gene reporter. The cellular systems biology (CSB™)
activities (expressions) in a given cell for a certain time approach (Cellumen “CellCiphr” profile) is used to measure
frame that helps to understand human diseases at the DNA damage-induced cytotoxicity in human cellular
molecular level. 101,102 Molecular targets can be recognized hepatic cell line HepG2 by activating p53 via a fluorescent
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by the consistent pattern of gene expression across large anti-p53 antibody. Another p53-dependent beta-
cohorts of human samples, which provide insights in lactamase reporter assay is the Invitrogen ‘CellSensor’ assay
evaluating treatment-related phenotypic changes on the to measure cytotoxicity in HCT‑116 cells. 118,119 The lack of
molecular basis. Indeed, distinct tumor subtypes in the same metabolic activation and the removal of genotoxic lesions by
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histological environment may present differential responses the DNA repair system could lead to high false negative.
that can cause remarkable hurdles for drug development ATAD5-luciferase assay developed by Fox et al. is based on
and treatment implications. The differential response to the ATAD5 protein expression levels on DNA damage. 120,121
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therapies may stem from heterogeneous patterns of gene ATAD5 is a suppressor of direct repeat recombination. 122
expression known as metagenes. These metagenes influence Using this assay, 22 antioxidant-compounds have
multiple physiological properties of tumors through various been identified including potential chemotherapeutic
signaling pathways, such as RAS and Myc, regulating agents (resveratrol, genistein, and baicalein) that offer
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the degree of epithelial-to-mesenchymal transition. 104-106 improvements over conventional cancer drugs. In
Rising incidences of drug resistance and limited efficacy 2018, Sykora et al. developed an advanced single-cell gel
against complex diseases exacerbate the difficulties of drug electrophoresis (SCGE) assay coupled with data processing
discovery. To address these bottlenecks, polypharmacology software (CometChip Platform) to identify and characterize
emerges as an innovative therapeutic strategy in the genotoxic agents in large compound libraries. This tool can
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realm of drug discovery. This approach involves using be applied to determine sensitivity to genotoxic exposures in
therapeutic molecules capable of interacting with multiple human populations for epidemiological studies. 123
biomolecular targets. However, the limitation of using
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this strategy involves toxicological concerns and potential 5. Application in cancer treatment
side effects. These complexities in molecular patterns Cancer treatment encounters a major obstacle in the form
underline the need for more efficient understanding of of resistance to chemotherapeutic agents. Tumor cells
drug MOA at phenotypic and pathway levels for making often develop a multidrug-resistant (MDR) phenotype
correct diagnostic and prognostic decisions. by altering the expression of transporter proteins, such
as the ATP‑binding cassette (ABC) superfamily. These
4. Screening for genotoxic compounds proteins play a crucial role in regulating intracellular
Genotoxicity in cancer cells can be induced by the treatment drug concentrations. In addition, resistance can arise
of chemotherapeutic agents, such as chlorambucil, through mechanisms like enhanced repair of drug-
cyclophosphamide, cisplatin, oxaliplatin, 5-fluorouracil, induced damage. The emergence of MDR phenotypes

Volume 3 Issue 1 (2024) 9 https://doi.org/10.36922/gtm.2448