Toxicogenomics profiling of bone marrow from rats treated with topotecan in combination with oxaliplatin: a mechanistic strategy to inform combination toxicity

Abstract

Combinations of anticancer agents may have synergistic anti-tumor effects, but enhanced hematological toxicity often limit their clinical use. We examined whether “microarray profiles” could be used to compare early molecular responses following a single dose of agents administered individually with that of the agents administered in a combination. We compared the mRNA responses within bone marrow of Sprague-Dawley rats after a single 30 min treatment with topotecan at 4.7 mg/kg or oxaliplatin at 15 mg/kg alone to that of sequentially administered combination therapy or vehicle control for 1, 6, and 24 h. We also examined the histopathology of the bone marrow following all treatments. Drug-related histopathological lesions were limited to bone marrow hypocellularity for animals dosed with either agent alone or in combination. Lesions had an earlier onset and higher incidence for animals given topotecan alone or in combination with oxaliplatin. Severity increased from mild to moderate when topotecan was administered prior to oxaliplatin compared with administering oxaliplatin first. Notably, six patterns of co-expressed genes were detected at the 1 h time point that indicate regulatory expression of genes that are dependent on the order of the administration. These results suggest alterations in histone biology, chromatin remodeling, DNA repair, bone regeneration, and respiratory and oxidative phosphorylation are among the prominent pathways modulated in bone marrow from animals treated with an oxaliplatin/topotecan combination. These data also demonstrate the potential for early mRNA patterns derived from target organs of toxicity to inform toxicological risk and molecular mechanisms for agents given in combination.

Elucidation of Mechanisms of Topotecan-Induced Cell Death in Human Breast MCF-7 Cancer Cells by Gene Expression Analysis

“…We have identified several genes belonging to the p53 signaling pathway, DNA replication, and positive regulators of apoptotic process that were differentially expressed by TPT treatment. Using microarray differential gene expression analysis, Davis et al (2015) have reported that topotecan exposure in rat bone marrow resulted in enrichment of cell cycle and DNA replication pathways similar to our observations in this study. It should be noted that the relationship between chromatin remodeling, cell cycle and DNA repair factors are usually not discussed in relation to DNA damage response mechanisms following topotecan exposure.…”

Transcriptomic profiles of tissues from rats treated with anticancer drug combinations

“…If this hypothesis is true, these patterns can then be used to provide some initial degree of discrimination between drug combinations with higher risk of combination toxicity. Initial evidence of this has been published where we show that the administration of oxaliplatin in combination with topotecan, or either drug alone, in the rat elicits gene expression changes in the bone marrow that are dependent on the order of the administration and indicative of enhance toxicity 1 .…”

“…RNA samples were converted into labeled target antisense RNA (cRNA) using the Single-Round RNA Amplification and Biotin Labeling System (Enzo Life Sciences, Farmingdale, NY). Microarray analysis was performed as previously described 1 . Briefly, 2.5 μg of total RNA was converted into double stranded cDNA via reverse transcription using an oligo-d(T) primer-adaptor.…”

“…Data extraction from the images was completed with the GeneChip Operating Software (GCOS) to generate CEL and CHP files. The microarray analysis method is an expanded version of descriptions in our related work 1 .…”

goSTAG: gene ontology subtrees to tag and annotate genes within a set

“…Details of the analysis are as previously described [10]. The data are available in the Gene Expression Omnibus (GEO) [11, 12] under accession number GSE63902.…”