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Low Recombination Proficiency Score (RPS) Predicts Heightened Sensitivity to DNA-Damaging Chemotherapy in Breast Cancer.

ABSTRACT: Purpose: Molecular-based cancer tests have been developed to augment the standard clinical and pathologic features used to tailor treatments to individual breast cancer patients. Homologous recombination (HR) repairs double-stranded DNA breaks and promotes tolerance to lesions that disrupt DNA replication. Recombination Proficiency Score (RPS) quantifies HR efficiency based on the expression of four genes involved in DNA damage repair. We hypothesized low RPS values can identify HR-deficient breast cancers most sensitive to DNA-damaging chemotherapy.Experimental Design: We collected pathologic tumor responses and tumor gene expression values for breast cancer patients that were prospectively enrolled on clinical trials involving preoperative chemotherapy followed by surgery (N = 513). We developed an algorithm to calculate breast cancer-specific RPS (RPSb) values on an individual sample basis.Results: Low RPSb tumors are approximately twice as likely to exhibit a complete pathologic response or minimal residual disease to preoperative anthracycline-based chemotherapy as compared with high RPSb tumors. Basal, HER2-enriched, and luminal B breast cancer subtypes exhibit low RPSb values. In addition, RPSb predicts treatment responsiveness after controlling for clinical and pathologic features, as well as intrinsic breast subtype.Conclusions: Overall, our findings indicate that low RPS breast cancers exhibit aggressive features at baseline, but they have heightened sensitivity to DNA-damaging chemotherapy. Low RPSb values in basal, HER2-enriched, and luminal B subtypes provide a mechanistic explanation for their clinical behaviors and genomic instability. RPSb augments standard clinical and pathologic features used to tailor treatments, thereby enabling more personalized treatment strategies for individual breast cancer patients. Clin Cancer Res; 23(15); 4493-500. ©2017 AACR.

SUBMITTER: Pitroda SP

PROVIDER: S-EPMC5540755 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Low Recombination Proficiency Score (RPS) Predicts Heightened Sensitivity to DNA-Damaging Chemotherapy in Breast Cancer.

Pitroda Sean P SP Bao Riyue R Andrade Jorge J Weichselbaum Ralph R RR Connell Philip P PP

Clinical cancer research : an official journal of the American Association for Cancer Research 20170324 15

<b>Purpose:</b> Molecular-based cancer tests have been developed to augment the standard clinical and pathologic features used to tailor treatments to individual breast cancer patients. Homologous recombination (HR) repairs double-stranded DNA breaks and promotes tolerance to lesions that disrupt DNA replication. Recombination Proficiency Score (RPS) quantifies HR efficiency based on the expression of four genes involved in DNA damage repair. We hypothesized low RPS values can identify HR-defici ...[more]

PMID: 28341751

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Project description:Synapses and circuits rely on homeostatic forms of regulation in order to transmit meaningful information. The Drosophila melanogaster neuromuscular junction (NMJ) is a well-studied synapse that shows robust homeostatic control of function. Most prior studies of homeostatic plasticity at the NMJ have centered on presynaptic homeostatic potentiation (PHP). PHP happens when postsynaptic muscle neurotransmitter receptors are impaired, triggering retrograde signaling that causes an increase in presynaptic neurotransmitter release. As a result, normal levels of evoked excitation are maintained. The counterpart to PHP at the NMJ is presynaptic homeostatic depression (PHD). Overexpression of the Drosophila vesicular glutamate transporter (VGlut) causes an increase in the amplitude of spontaneous events. PHD happens when the synapse responds to the challenge by decreasing quantal content (QC) during evoked neurotransmissionagain, resulting in normal levels of postsynaptic excitation. We hypothesized that there may exist a class of molecules that affects both PHP and PHD. Impairment of any such molecule could hurt a synapses ability to respond to any significant homeostatic challenge. We conducted an electrophysiology-based screen for blocks of PHD. We did not observe a block of PHD in the genetic conditions screened, but we found loss-of-function conditions that led to a substantial deficit in evoked amplitude when combined with VGlut overexpression. The conditions causing this phenotype included a double heterozygous loss-of-function condition for genes encoding the inositol trisphosphate receptor (IP3R itpr) and ryanodine receptor (RyR). IP3Rs and RyRs gate calcium release from intracellular stores. Pharmacological agents targeting IP3R and RyR recapitulated the genetic losses of these factors, as did lowering calcium levels from other sources. Our data are consistent with the idea that the homeostatic signaling process underlying PHD is especially sensitive to levels of calcium at the presynapse.

Dataset Information

Low Recombination Proficiency Score (RPS) Predicts Heightened Sensitivity to DNA-Damaging Chemotherapy in Breast Cancer.

Publications

Low Recombination Proficiency Score (RPS) Predicts Heightened Sensitivity to DNA-Damaging Chemotherapy in Breast Cancer.

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