PARP inhibition (PARPi) has modest clinical activity in recurrent
-mutant (
) high-grade serous ovarian cancers (HGSOC). We hypothesized that PARPi increases dependence on ATR/CHK1 such that ...combination PARPi with ATR/CHK1 blockade results in increased cell death and tumor regression.
Effects of PARPi (olaparib), CHK1 inhibition (CHK1i;MK8776), or ATR inhibition (ATRi;AZD6738) alone or in combination on survival, colony formation, cell cycle, genome instability, and apoptosis were evaluated in
HGSOC cells. Tumor growth
was evaluated using a
patient-derived xenograft (PDX) model.
PARPi monotherapy resulted in a decrease in
cell survival, colony formation and suppressed but did not eliminate tumor growth at the maximum tolerated dose (MTD) in a
PDX. PARPi treatment increased pATR and pCHK1, indicating activation of the ATR-CHK1 fork protection pathway is relied upon for genome stability under PARPi. Indeed, combination of ATRi or CHK1i with PARPi synergistically decreased survival and colony formation compared with single-agent treatments in
cells. Notably, PARPi led to G
phase accumulation, and the addition of ATRi or CHK1i released cells from G
causing premature mitotic entry with increased chromosomal aberrations and apoptosis. Moreover, the combinations of PARPi with ATRi or CHK1i were synergistic in causing tumor suppression in a
PDX with the PARPi-ATRi combination inducing tumor regression and in most cases, complete remission.
PARPi causes increased reliance on ATR/CHK1 for genome stability, and combination PARPi with ATR/CHK1i is more effective than PARPi alone in reducing tumor burden in
models.
.
The ATR-CHK1 axis stabilizes stalled replication forks and prevents their collapse into DNA double-strand breaks (DSBs). Here, we show that fork collapse in Atr-deleted cells is mediated through the ...combined effects the sumo targeted E3-ubiquitin ligase RNF4 and activation of the AURKA-PLK1 pathway. As indicated previously, Atr-deleted cells exhibited a decreased ability to restart DNA replication following fork stalling in comparison with control cells. However, suppression of RNF4, AURKA, or PLK1 returned the reinitiation of replication in Atr-deleted cells to near wild-type levels. In RNF4-depleted cells, this rescue directly correlated with the persistence of sumoylation of chromatin-bound factors. Notably, RNF4 repression substantially suppressed the accumulation of DSBs in ATR-deficient cells, and this decrease in breaks was enhanced by concomitant inhibition of PLK1. DSBs resulting from ATR inhibition were also observed to be dependent on the endonuclease scaffold protein SLX4, suggesting that RNF4 and PLK1 either help activate the SLX4 complex or make DNA replication fork structures accessible for subsequent SLX4-dependent cleavage. Thus, replication fork collapse following ATR inhibition is a multistep process that disrupts replisome function and permits cleavage of the replication fork.
Childhood adversity is associated with a host of mental and physical health problems across the lifespan. Individuals who have experienced childhood adversity (e.g., child abuse and neglect, family ...conflict, poor parent/child relationships, low socioeconomic status or extreme poverty) are at a greater risk for morbidity and premature mortality than those not exposed to childhood adversity. Several mechanisms likely contribute to the relationship between childhood adversity and health across the lifespan (e.g., health behaviors, cardiovascular reactivity). In this paper, we review a large body of research within the field of psychoneuroimmunology, demonstrating the relationship between early life stress and alterations of the immune system. We first review the literature demonstrating that childhood adversity is associated with immune dysregulation across different indices, including proinflammatory cytokine production (and its impact on telomere length), illness and infection susceptibility, latent herpesvirus reactivation, and immune response to a tumor. We then summarize the growing literature on how childhood adversity may alter epigenetic processes. Finally, we propose future directions related to this work that have basic and applied implications.
Key points
We investigated the influence of arterial PCO2 (PaCO2) with and without acutely elevated arterial pH and bicarbonate (HCO3–) on cerebral blood flow (CBF) regulation in the internal carotid ...artery and vertebral artery.
We assessed stepwise iso‐oxic alterations in PaCO2 (i.e. cerebrovascular CO2 reactivity) prior to and following i.v. sodium bicarbonate infusion (NaHCO3–) to acutely elevate arterial pH and HCO3–.
Total CBF was unchanged irrespective of a higher arterial pH at each matched stage of PaCO2, indicating that CBF is acutely regulated by PaCO2 rather than arterial pH.
The cerebrovascular responses to changes in arterial H+/pH were altered in keeping with the altered relationship between PaCO2 and H+/pH following NaHCO3– infusion (i.e. changes in buffering capacity).
Total CBF was ∼7% higher following NaHCO3– infusion during isocapnic breathing providing initial evidence for a direct vasodilatory influence of HCO3– independent of PaCO2 levels.
Cerebral blood flow (CBF) regulation is dependent on the integrative relationship between arterial PCO2 (PaCO2), pH and cerebrovascular tone; however, pre‐clinical studies indicate that intrinsic sensitivity to pH, independent of changes in PaCO2 or intravascular bicarbonate (HCO3–), principally influences cerebrovascular tone. Eleven healthy males completed a standardized cerebrovascular CO2 reactivity (CVR) test utilizing radial artery catheterization and Duplex ultrasound (CBF); consisting of matched stepwise iso‐oxic alterations in PaCO2 (hypocapnia: –5, –10 mmHg; hypercapnia: +5, +10 mmHg) prior to and following i.v. sodium bicarbonate (NaHCO3–; 8.4%, 50 mEq 50 mL–1) to elevate pH (7.408 ± 0.020 vs. 7.461 ± 0.030; P < 0.001) and HCO3– (26.1 ± 1.4 vs. 29.3 ± 0.9 mEq L–1; P < 0.001). Absolute CBF was not different at each stage of CO2 reactivity (P = 0.629) following NaHCO3–, irrespective of a higher pH (P < 0.001) at each matched stage of PaCO2 (P = 0.927). Neither hypocapnic (3.44 ± 0.92 vs. 3.44 ± 1.05% per mmHg PaCO2; P = 0.499), nor hypercapnic (7.45 ± 1.85 vs. 6.37 ± 2.23% per mmHg PaCO2; P = 0.151) reactivity to PaCO2 were altered pre‐ to post‐NaHCO3–. When indexed against arterial H+, the relative hypocapnic CVR was higher (P = 0.019) and hypercapnic CVR was lower (P = 0.025) following NaHCO3–, respectively. These changes in reactivity to H+ were, however, explained by alterations in buffering between PaCO2 and arterial H+/pH consequent to NaHCO3–. Lastly, CBF was higher (688 ± 105 vs. 732 ± 89 mL min–1, 7% ± 12%; P = 0.047) following NaHCO3– during isocapnic breathing providing support for a direct influence of HCO3– on cerebrovascular tone independent of PaCO2. These data indicate that in the setting of acute metabolic alkalosis, CBF is regulated by PaCO2 rather than arterial pH.
Key points
We investigated the influence of arterial PCO2 (PaCO2) with and without acutely elevated arterial pH and bicarbonate (HCO3–) on cerebral blood flow (CBF) regulation in the internal carotid artery and vertebral artery.
We assessed stepwise iso‐oxic alterations in PaCO2 (i.e. cerebrovascular CO2 reactivity) prior to and following i.v. sodium bicarbonate infusion (NaHCO3–) to acutely elevate arterial pH and HCO3–.
Total CBF was unchanged irrespective of a higher arterial pH at each matched stage of PaCO2, indicating that CBF is acutely regulated by PaCO2 rather than arterial pH.
The cerebrovascular responses to changes in arterial H+/pH were altered in keeping with the altered relationship between PaCO2 and H+/pH following NaHCO3– infusion (i.e. changes in buffering capacity).
Total CBF was ∼7% higher following NaHCO3– infusion during isocapnic breathing providing initial evidence for a direct vasodilatory influence of HCO3– independent of PaCO2 levels.
Purpose of Review
To synthesize the critical role of obesity-associated inflammation, dietary factors, and nutrition in determining breast cancer risk.
Recent Findings
Obesity-associated inflammation ...is strongly linked to breast cancer risk and progression, largely via two processes: inflammatory pathways and dysregulated metabolism. Cytokine production in excess adipose tissues creates a chronic inflammatory microenvironment, which favors tumor development. Lifestyle factors, including diet, have long been recognized as important determinants of breast cancer risk and mortality.
Summary
Obesity increases the risk of developing breast cancer in both pre- and postmenopausal women and also negatively affects breast cancer recurrence and survival. Poor dietary habits characterized by the high intake of refined starches, sugar, and both saturated and trans-saturated fats, as well as the low intake of omega-3 fatty acids, natural antioxidants, and fiber, modulate inflammation and, thereby, appear to be linked to increased risk of breast cancer and mortality.
Objective: The loss of a spouse is considered one of the most significant life change-related stressors. Bereaved spouses have significantly increased risk of chronic inflammation, and ultimately ...greater morbidity and mortality. High levels of proinflammatory cytokines are related to negative health outcomes. In bereavement, the ability to successfully regulate emotion is a vital skill for healthy coping and may represent a key psychological mechanism accounting for varying degrees of resilience. Psychological distancing is a frequently adaptive emotion regulation strategy in which an individual appraises a negative situation by taking a step back and distancing oneself, and coolly evaluates what is happening. The objective of the present work was to investigate whether psychological distancing, implemented implicitly via natural language use (i.e., linguistic distancing LD), is related to inflammation and bereavement-related health indicators. Method: Participants (N = 144) underwent a blood draw for the inflammation assay, completed questionnaire measures evaluating grief symptoms and health, and completed an oral task describing their relationship with their deceased spouse, which was used for the lexical analyses. Results: We found that LD was significantly associated with a panel of a priori proinflammatory stimulated cytokines (TNF-α, IL-6, IFN-γ, IL-17A, and IL-2), bereavement-related health indices, and the relationship between grief symptoms and inflammation varied depending on the participants' implementation of LD. Conclusions: LD may have a buffering effect for this vulnerable population. This work elucidates novel dependencies among language, emotion, and health. This work identifies resilience factors and probes the translational value of LD.
Oncogenic Ras and p53 loss-of-function mutations are common in many advanced sporadic malignancies and together predict a limited responsiveness to conventional chemotherapy. Notably, studies in ...cultured cells have indicated that each of these genetic alterations creates a selective sensitivity to ataxia telangiectasia and Rad3-related (ATR) pathway inhibition. Here, we describe a genetic system to conditionally reduce ATR expression to 10% of normal levels in adult mice to compare the impact of this suppression on normal tissues and cancers in vivo. Hypomorphic suppression of ATR minimally affected normal bone marrow and intestinal homeostasis, indicating that this level of ATR expression was sufficient for highly proliferative adult tissues. In contrast, hypomorphic ATR reduction potently inhibited the growth of both p53-deficient fibrosarcomas expressing H-rasG12V and acute myeloid leukemias (AMLs) driven by MLL-ENL and N-rasG12D. Notably, DNA damage increased in a greater-than-additive fashion upon combining ATR suppression with oncogenic stress (H-rasG12V, K-rasG12D, or c-Myc overexpression), indicating that this cooperative genome-destabilizing interaction may contribute to tumor selectivity in vivo. This toxic interaction between ATR suppression and oncogenic stress occurred without regard to p53 status. These studies define a level of ATR pathway inhibition in which the growth of malignancies harboring oncogenic mutations can be suppressed with minimal impact on normal tissue homeostasis, highlighting ATR inhibition as a promising therapeutic strategy.
The death of a spouse is associated with maladaptive immune alterations; grief severity may exacerbate this link. We investigated whether high grief symptoms were associated with an amplified ...inflammatory response to subsequent stress among 111 recently bereaved older adults. Participants completed a standardized psychological stressor and underwent a blood draw before, 45 min after, and 2 hr after the stressor. Those experiencing high grief symptoms (i.e., scoring > 25 on the Inventory of Complicated Grief) experienced a 45% increase in interleukin-6 (IL-6; a proinflammatory cytokine) per hour, whereas those experiencing low grief symptoms demonstrated a 26% increase. In other words, high grief was related to a 19% increase in IL-6 per hour relative to low grief. The grief levels of recently bereaved people were associated with the rate of change in IL-6 following a subsequent stressor, above and beyond depressive symptoms. This is the first study to demonstrate that high grief symptoms promote inflammation following acute stress.
Previous studies indicate that oncogenic stress activates the ATR-Chk1 pathway. Here, we show that ATR-Chk1 pathway engagement is essential for limiting genomic instability following oncogenic Ras ...transformation. ATR pathway inhibition in combination with oncogenic Ras expression synergistically increased genomic instability, as quantified by chromatid breaks, sister chromatid exchanges, and H2AX phosphorylation. This level of instability was significantly greater than that observed following ATR suppression in untransformed control cells. In addition, consistent with a deficiency in long-term genome maintenance, hypomorphic ATR pathway reduction to 16% of normal levels was synthetic lethal with oncogenic Ras expression in cultured cells. Notably, elevated genomic instability and synthetic lethality following suppression of ATR were not due to accelerated cycling rates in Ras-transformed cells, indicating that these synergistic effects were generated on a per-cell-cycle basis. In contrast to the synthetic lethal effects of hypomorphic ATR suppression, subtle reduction of ATR expression (haploinsufficiency) in combination with endogenous levels of K-ras(G12D) expression elevated the incidence of lung adenocarcinoma, spindle cell sarcoma, and thymic lymphoma in p53 heterozygous mice. K-ras(G12D)-induced tumorigenesis in ATR(+/-)p53(+/-) mice was associated with intrachromosomal deletions and loss of wild-type p53. These findings indicate that synergistic increases in genomic instability following ATR reduction in oncogenic Ras-transformed cells can produce 2 distinct biological outcomes: synthetic lethality upon significant suppression of ATR expression and tumor promotion in the context of ATR haploinsufficiency. These results highlight the importance of the ATR pathway both as a barrier to malignant progression and as a potential target for cancer treatment.
During pregnancy, there are significant physiological changes to support a healthy fetus. Parasympathetic activity normatively decreases across pregnancy, and psychological stress can promote even ...further decreased heart rate variability (HRV). This study evaluated (1) changes in vagally-mediated HRV from pregnancy to postpartum, (2) changes in vagally-mediated HRV from pregnancy to postpartum based on negative partner relationship qualities, and (3) changes in depressive symptoms from pregnancy to postpartum based on negative partner relationship qualities. 78 participants in their 3rd trimester self-reported their relationship quality with their partner at the first visit. Depressive symptoms and vagally-mediated HRV were evaluated at rest at five time points from 3rd trimester to 12 months postpartum. On average, the only significant increase in vagally-mediated HRV occurred between the 3rd trimester and 4–6 weeks postpartum. However, those who reported more negative partner relationship qualities during their 3rd trimester of pregnancy maintained lower vagally-mediated HRV levels across all of the first year postpartum and significantly lower vagally-mediated HRV at both 4 and 8 months postpartum as compared to people who reported fewer negative partner relationship qualities. Across the first year postpartum, people reporting more negative partner relationship qualities experienced more severe depressive symptoms than their counterparts with fewer negative partner relationship qualities; however, there was no difference in the rate of change of depressive symptoms across the first year postpartum based on negative partner relationship qualities. Because lower vagally-mediated HRV is associated with depressive symptoms, future work should explore the temporal relationship between vagally-mediated HRV and depressive symptoms in the postpartum period.
•We assessed heart rate variability (HRV) and depressive symptoms from 3rd trimester to 12 months postpartum.•HRV increased between women’s 3rd trimester of pregnancy and 4–6 weeks postpartum.•Women in more negative partner relationships during their 3rd trimester of pregnancy had lower postpartum HRV levels.•Women in more negative partner relationships had more severe postpartum depressive symptoms.•No reliable difference in the rate of change of HRV or depressive symptoms based on partner relationship qualities.
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