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Circadian Influences on Chemotherapy Efficacy in a Mouse Model of Brain Metastases of Breast Cancer.

ABSTRACT: Chemotherapy is more effective in the treatment of peripheral tumors than brain metastases, likely reflecting the reduced ability of chemotherapy to cross the blood-brain barrier (BBB) and blood-tumor barrier at efficacious concentrations. Recent studies demonstrate circadian regulation of the BBB. Thus, we predicted that optimally timed chemotherapy would increase anti-tumor efficacy in a model of brain metastases of breast cancer (BMBC). First, we characterized novel daily alterations in BBB permeability to a commonly used chemotherapeutic, ¹⁴C-paclitaxel, within BMBC following injections given at four time points across the day. Peak and trough ¹⁴C-paclitaxel concentrations within BMBC occurred during the mid-dark phase and at the beginning of the light phase, respectively. Notably, chemotherapy injections during the dark phase increased cell death within BMBC and delayed onset of neurological symptoms relative to injections during the light phase. These data provide strong evidence for the beneficial effects of chrono-chemotherapy for the treatment of BMBC.

SUBMITTER: Walker WH

PROVIDER: S-EPMC8695439 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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Circadian Influences on Chemotherapy Efficacy in a Mouse Model of Brain Metastases of Breast Cancer.

Walker William H WH Sprowls Samuel A SA Bumgarner Jacob R JR Liu Jennifer A JA Meléndez-Fernández O Hecmarie OH Walton James C JC Lockman Paul R PR DeVries A Courtney AC Nelson Randy J RJ

Frontiers in oncology 20211209

Chemotherapy is more effective in the treatment of peripheral tumors than brain metastases, likely reflecting the reduced ability of chemotherapy to cross the blood-brain barrier (BBB) and blood-tumor barrier at efficacious concentrations. Recent studies demonstrate circadian regulation of the BBB. Thus, we predicted that optimally timed chemotherapy would increase anti-tumor efficacy in a model of brain metastases of breast cancer (BMBC). First, we characterized novel daily alterations in BBB p ...[more]

PMID: 34956876

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Project description:Gene Expression Profiling of a Mouse Xenograft Model of “Triple-Negative” Breast Cancer Brain Metastases With and Without Vorinostat Treatment. Purpose: As chemotherapy and molecular therapy improve the systemic survival of breast cancer patients, the incidence of brain metastases increases. Few therapeutic strategies exist for the treatment of brain metastases because the blood-brain barrier severely limits drug access. We report the pharmacokinetic, efficacy, and mechanism of action studies for the histone deactylase inhibitor vorinostat (suberoylanilide hydroxamic acid) in a preclinical model of brain metastasis of triple-negative breast cancer. Experimental Design: The 231-BR brain trophic subline of the MDA-MB-231 human breast cancer cell line was injected into immunocompromised mice for pharmacokinetic and metastasis studies. Pharmacodynamic studies compared histone acetylation, apoptosis, proliferation, and DNA damage in vitro and in vivo. Results: Following systemic administration, uptake of [14C]vorinostat was significant into normal rodent brain and accumulation was up to 3-fold higher in a proportion of metastases formed by 231-BR cells. Vorinostat prevented the development of 231-BR micrometastases by 28% (P = 0.017) and large metastases by 62% (P < 0.0001) compared with vehicle-treated mice when treatment was initiated on day 3 post-injection. The inhibitory activity of vorinostat as a single agent was linked to a novel function in vivo: induction of DNA double-strand breaks associated with the down-regulation of the DNA repair gene Rad52. Conclusions: We report the first preclinical data for the prevention of brain metastasis of triple-negative breast cancer. Vorinostat is brain permeable and can prevent the formation of brain metastases by 62%. Its mechanism of action involves the induction of DNA double-strand breaks, suggesting rational combinations with DNA active drugs or radiation. Experiment Overall Design: We performed gene expression profiling on metastases from vehicle- or vorinostat-treated mice to determine if alterations in gene expression were observable that were consistent with the phenotypes observed. Brain metastases from five vehicle-treated mice and six 150 mg/kg vorinostat-treated mice were procured by laser capture microdissection. RNA was extracted from the captured tumor cells from each brain and two rounds of linear amplification was done. The amplified RNA from each mouse was processed separately through microarray hybridization and analysis.

Dataset Information

Circadian Influences on Chemotherapy Efficacy in a Mouse Model of Brain Metastases of Breast Cancer.

Publications

Circadian Influences on Chemotherapy Efficacy in a Mouse Model of Brain Metastases of Breast Cancer.

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