Characterization of the generic mutant p53-rescue compounds in a broad range of assays.

Dozens of compounds that rescue tumor-associated mutant p53 have been reported. Xiao et al. perform 10 assays to evaluate effectiveness of the mutant p53-rescue compounds side-by-side but do not detect reliable rescue in any assay for the evaluated compounds, except for ATO and its analog PAT.

Decitabine induces IRF7-mediated immune responses in p53-mutated triple-negative breast cancer: a clinical and translational study.

p53 is mutated in half of cancer cases. However, no p53-targeting drugs have been approved. Here, we reposition decitabine for triple-negative breast cancer (TNBC), a subtype with frequent p53 mutations and extremely poor prognosis. In a retrospective study on tissue microarrays with 132 TNBC cases, DNMT1 overexpression was associated with p53 mutations (P = 0.037) and poor overall survival (OS) (P = 0.010). In a prospective DEciTabinE and Carboplatin in TNBC (DETECT) trial (NCT03295552), decitabine with carboplatin produced an objective response rate (ORR) of 42% in 12 patients with stage IV TNBC. Among the 9 trialed patients with available TP53 sequencing results, the 6 patients with p53 mutations had higher ORR (3/6 vs. 0/3) and better OS (16.0 vs. 4.0 months) than the patients with wild-type p53. In a mechanistic study, isogenic TNBC cell lines harboring DETECT-derived p53 mutations exhibited higher DNMT1 expression and decitabine sensitivity than the cell line with wild-type p53. In the DETECT trial, decitabine induced strong immune responses featuring the striking upregulation of the innate immune player IRF7 in the p53-mutated TNBC cell line (upregulation by 16-fold) and the most responsive patient with TNBC. Our integrative studies reveal the potential of repurposing decitabine for the treatment of p53-mutated TNBC and suggest IRF7 as a potential biomarker for decitabine-based treatments.

AcGlcAs: A Novel P53-Targeting Arsenical with Potent Cellular Uptake and Cancer Cell Selectivity.

Arsenic trioxide (ATO) targets PML/RARα and leads to miraculous success in treating acute promyelocytic leukemia. Notably, ATO also targets p53, the most frequently mutated protein in cancers, through a similar binding mechanism. However, p53-targeting ATO trials are challenging due to the poor cellular uptake and cancer selectivity of ATO. Here, we analyzed the structure-activity relationship of arsenicals and rationally developed a novel arsenical (designated AcGlcAs) by conjugating arsenic to sulfur atoms and tetraacetyl-ß-d-thioglucose. AcGlcAs exhibited remarkable cellular uptake through a thiol-mediated pathway (maximally 127-fold higher than ATO), thereby potently targeting PML/RARα and mutant p53. Among the 55 tested cell lines, AcGlcAs preferentially killed cancer lines rather than normal lines. In preclinical studies, AcGlcAs significantly extended the survival of mice bearing a xenograft tumor with p53 mutation while showing high plasma stability and oral bioavailability. Thus, AcGlcAs is a potential clinical candidate for precisely treating numerous p53-mutated cancers.

Arsenic trioxide extends survival of Li-Fraumeni syndrome mimicking mouse.

Li-Fraumeni syndrome (LFS) is characterized by germline mutations occurring on one allele of genome guardian TP53. It is a severe cancer predisposition syndrome with a poor prognosis, partly due to the frequent development of subsequent primary tumors following DNA-damaging therapies. Here we explored, for the first time, the effectiveness of mutant p53 rescue compound in treating LFS-mimicking mice harboring a deleterious p53 mutation. Among the ten p53 hotspot mutations in IARC LFS cohorts, R282W is one of the mutations predicting the poorest survival prognosis and the earliest tumor onset. Among the six clinical-stage mutant p53 rescue compounds, arsenic trioxide (ATO) effectively restored transactivation activity to p53-R282W. We thus constructed a heterozygous Trp53 R279W (corresponding to human R282W) mouse model for the ATO treatment study. The p53R279W/+ (W/+) mice exhibited tumor onset and overall survival well mimicking the ones of human LFS. Further, 35 mg/L ATO addition in drink water significantly extended the median survival of W/+ mice (from 460 to 596 days, hazard ratio = 0.4003, P = 0.0008). In the isolated tumors from ATO-treated W/+ mice, the representative p53 targets including Cdkn1a, Mdm2, and Tigar were significantly upregulated, accompanying with a decreased level of the proliferation marker Ki67 and increased level of apoptosis marker TUNEL. Together, the non-genotoxic treatment of p53 rescue compound ATO holds promise as an alternative for LFS therapeutic.

Diverse rescue potencies of p53 mutations to ATO are predetermined by intrinsic mutational properties.

Tumor suppressor p53 is inactivated by thousands of heterogeneous mutations in cancer, but their individual druggability remains largely elusive. Here, we evaluated 800 common p53 mutants for their rescue potencies by the representative generic rescue compound arsenic trioxide (ATO) in terms of transactivation activity, cell growth inhibition, and mouse tumor-suppressive activities. The rescue potencies were mainly determined by the solvent accessibility of the mutated residue, a key factor determining whether a mutation is a structural one, and the temperature sensitivity, the ability to reassemble the wild-type DNA binding surface at a low temperature, of the mutant protein. A total of 390 p53 mutants were rescued to varying degrees and thus were termed as type 1, type 2a, and type 2b mutations, depending on the degree to which they were rescued. The 33 type 1 mutations were rescued to amounts comparable to the wild type. In PDX mouse trials, ATO preferentially inhibited growth of tumors harboring type 1 and type 2a mutants. In an ATO clinical trial, we report the first-in-human mutant p53 reactivation in a patient harboring the type 1 V272M mutant. In 47 cell lines derived from 10 cancer types, ATO preferentially and effectively rescued type 1 and type 2a mutants, supporting the broad applicability of ATO in rescuing mutant p53. Our study provides the scientific and clinical communities with a resource of the druggabilities of numerous p53 mutations (www.rescuep53.net) and proposes a conceptual p53-targeting strategy based on individual mutant alleles rather than mutation type.

Developmental arsenic exposure impairs cognition, directly targets DNMT3A, and reduces DNA methylation.

Developmental arsenic exposure has been associated with cognitive deficits in epidemiological studies, but the underlying mechanisms remain poorly understood. Here, we establish a mouse model of developmental arsenic exposure exhibiting deficits of recognition and spatial memory in the offspring. These deficits are associated with genome-wide DNA hypomethylation and abnormal expression of cognition-related genes in the hippocampus. Arsenic atoms directly bind to the cysteine-rich ADD domain of DNA methyltransferase 3A (DNMT3A), triggering ubiquitin- and proteasome-mediated degradation of DNMT3A in different cellular contexts. DNMT3A degradation leads to genome-wide DNA hypomethylation in mouse embryonic fibroblasts but not in non-embryonic cell lines. Treatment with metformin, a first-line antidiabetic agent reported to increase DNA methylation, ameliorates the behavioral deficits and normalizes the aberrant expression of cognition-related genes and DNA methylation in the hippocampus of arsenic-exposed offspring. Our study establishes a DNA hypomethylation effect of developmental arsenic exposure and proposes a potential treatment against cognitive deficits in the offspring of pregnant women in arsenic-contaminated areas.

Repurposing antiparasitic antimonials to noncovalently rescue temperature-sensitive p53 mutations.

The tumor suppressor p53 is inactivated by over hundreds of heterogenous mutations in cancer. Here, we purposefully selected phenotypically reversible temperature-sensitive (TS) p53 mutations for pharmacological rescue with thermostability as the compound-screening readout. This rational screening identified antiparasitic drug potassium antimony tartrate (PAT) as an agent that can thermostabilize the representative TS mutant p53-V272M via noncovalent binding. PAT met the three basic criteria for a targeted drug: availability of a co-crystal structure, compatible structure-activity relationship, and intracellular target specificity, consequently exhibiting antitumor activity in a xenograft mouse model. At the antimony dose in clinical antiparasitic therapy, PAT effectively and specifically rescued p53-V272M in patient-derived primary leukemia cells in single-cell RNA sequencing. Further scanning of 815 frequent p53-missense mutations identified 65 potential PAT-treatable mutations, most of which were temperature sensitive. These results lay the groundwork for repurposing noncovalent antiparasitic antimonials for precisely treating cancers with the 65 p53 mutations.

Quality Improvement Project to Reduce Opioid Use in Patients Undergoing Cesarean Birth.

After observing the effectiveness of Enhanced Recovery After Surgery (ERAS) protocols for gynecological surgery patients, an interdisciplinary team initiated a quality improvement project with an ERAS protocol to minimize opioid use of patients undergoing elective cesarean birth. Secondary outcomes during the three-month project included decreasing the patient's length of stay and inpatient care costs. We used the Lean Six Sigma methodology and measured aggregated patient outcomes of opioid use, length of hospital stay, and total cost. In addition, we incorporated the ERAS protocol into the electronic health record. Results showed a reduction use of morphine milligram equivalents of opioids, a slight decrease in length of hospital stay, and no change in the inpatient costs. The team recognized that implementation of an ERAS protocol is a best practice to reduce opioid use in patients undergoing a cesarean birth and decided to permanently include it in patient care processes.

Three optimized assays for the evaluation of compounds that can rescue p53 mutants.

Identifying drugs targeting p53 remains a major focus of precision oncology, with over twenty compounds that can rescue p53 mutants reported. Here, we suggest three easily accessible assays to determine the thermostability, protein folding, and transcriptional activity of p53 mutants-the go-to criteria for evaluating a rescue compound that acts by increasing p53 thermostability. Because of the diversity of p53 mutants, a compound that meets the criteria of one assay does not necessarily meet the criteria of the other assays. For complete details on the use and execution of this protocol, please refer to Chen et al. (2021).

Arsenic Trioxide Rescues Structural p53 Mutations through a Cryptic Allosteric Site.

TP53 is the most frequently mutated gene in cancer, yet these mutations remain therapeutically non-actionable. Major challenges in drugging p53 mutations include heterogeneous mechanisms of inactivation and the absence of broadly applicable allosteric sites. Here we report the identification of small molecules, including arsenic trioxide (ATO), an established agent in treating acute promyelocytic leukemia, as cysteine-reactive compounds that rescue structural p53 mutations. Crystal structures of arsenic-bound p53 mutants reveal a cryptic allosteric site involving three arsenic-coordinating cysteines within the DNA-binding domain, distal to the zinc-binding site. Arsenic binding stabilizes the DNA-binding loop-sheet-helix motif alongside the overall ß-sandwich fold, endowing p53 mutants with thermostability and transcriptional activity. In cellular and mouse xenograft models, ATO reactivates mutant p53 for tumor suppression. Investigation of the 25 most frequent p53 mutations informs patient stratification for clinical exploration. Our results provide a mechanistic basis for repurposing ATO to target p53 mutations for widely applicable yet personalized cancer therapies.

Early Identification of Delirium in Intensive Care Unit Patients: Improving the Quality of Care.

BACKGROUND: Delirium has long-term consequences for intensive care unit patients. The project site, an urban academic hospital, did not previously use a validated delirium screening tool, and patients commonly received sedative medications to treat agitation. OBJECTIVE: To minimize the risk of delirium by implementing the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) as the standard-of-care delirium assessment tool in the intensive care unit and by decreasing use of high-risk medications (ie, opioids and benzodiazepines). METHODS: An observational pretest-posttest design was used to analyze deidentified patient data from electronic health records. The evidence-based practice intervention focused on educating nurses on high-risk medications and CAM-ICU implementation. Control charts, χ2 tests, and mixed regression models were used to evaluate the effectiveness of the intervention in reducing delirium risk by decreasing use of high-risk medications. RESULTS: High-risk medication use significantly decreased after intervention among patients at low risk for delirium (before intervention, 7.37%; after intervention, 3.92%; P < .001) and at high risk for delirium (before intervention, 4.73%; after intervention, 2.99%; P < .001). Hospital stays were significantly shorter in patients at low risk than at high risk for delirium (P < .001) but increased by a mean of 0.13 days with each additional high-risk medication used (P < .001). CONCLUSIONS: The variation of high-risk medication use was significantly controlled with the implementation of CAM-ICU and education. Nurses felt that hands-on training with the CAM-ICU increased their comfort in identifying patients at risk for delirium. Future work will focus on assessment accuracy.

CDK9 inhibitors reactivate p53 by downregulating iASPP.

Loss of p53's tumor-suppressive function, either via TP53 mutation or hyperactive p53 inhibitory proteins, is one of the most frequent events in the development of human cancer. Here, we describe a strategy of pharmacologically inhibiting iASPP, a negative regulator of p53, to restore wild-type p53's tumor-suppressive function. iASPP knockdown in the colon cancer cell line HCT116 efficiently promoted p53's transcriptional activity and induced p53-dependent cell death, suggesting a key role for iASPP in silencing p53 in this cell line. Screening of a preclinical and clinical drug library using isogenic HCT116 cell models revealed that cyclin-dependent kinase 9 (CDK9) inhibitors preferentially inhibit p53+/+, rather than p53-/-, cells. Mechanistically, CDK9 inhibitors downregulated iASPP at the transcriptional level. This downregulation was dose- and time-dependent. CDK9 inhibitors further showed synergistic effects in killing p53+/+ HCT116 cells when combined with the MDM2 inhibitor Nutlin-3. In a large TCGA pan-cancer cohort, iASPP overexpression predicted poor overall survival (OS) in wild-type p53 patients, with worse OS observed when MDM2 was simultaneously overexpressed. Our study identifies CDK9 inhibitors as p53-reactivating agents, and proposes a strategy to treat cancer by efficiently reactivating p53 via the concurrent inhibition of iASPP and MDM2.

(±)-Equol does not interact with genistein on estrogen-dependent breast tumor growth.

Equol (EQ) is a prominent microbial metabolite of the soy isoflavone, daidzein, with estrogen-like properties. The major soy isoflavone, genistein (GEN), stimulated growth of estrogen-dependent breast cancer (EDBC) cells in vitro and tumor growth in vivo but EQ did not. To understand possible interactions of EQ and GEN on EDBC, EQ was used with GEN in combination in vitro and in vivo. Effects of EQ, GEN and EQ + GEN were evaluated using MCF-7 and T47D EDBC. Ovariectomized athymic mice were used as a model for in vivo tumor growth. Dietary EQ had no effect on MCF-7 tumor growth and the absence of effect was confirmed using a T47D EDBC in vivo model. EQ alone or in combination with GEN increased EDBC cell proliferation in vitro. EQ alone neither stimulated EDBC tumor growth in vivo at various doses nor suppressed tumor growth induced by dietary GEN. In summary, EQ has similar estrogenic effect as GEN in vitro but does not interact with GEN on EDBC tumor growth. Based on the evidence presented here, dietary EQ is unlikely to have estrogenic effects in vivo.

Neuroprotective Effects of Four Phenylethanoid Glycosides on H2O2-Induced Apoptosis on PC12 Cells via the Nrf2/ARE Pathway.

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor against oxidative stress and neurodegenerative disorders. Phenylethanoid glycosides (PhGs; salidroside, acteoside, isoacteoside, and echinacoside) exhibit antioxidant and neuroprotective bioactivities. This study was performed to investigate the neuroprotective effect and molecular mechanism of PhGs. PhGs pretreatment significantly suppressed H2O2-induced cytotoxicity in PC12 cells by triggering the nuclear translocation of Nrf2 and reversing the downregulated protein expression of heme oxygenase 1 (HO-1), NAD(P)H quinone oxidoreductase 1 (NQO1), glutamate cysteine ligase-catalytic subunit (GCLC), and glutamate-cysteine ligase modifier subunit (GCLM). Nrf2 siRNA or HO-1 inhibitor zinc protoporphyrin (ZnPP) reduced the neuroprotective effect. PhGs showed potential interaction with the Nrf2 binding site in Kelch-like ECH-association protein 1 (Keap1). This result may support the hypothesis that PhGs are activators of Nrf2. We demonstrated the potential binding between PhGs and the Keap1-activated Nrf2/ARE pathway, and that PhGs with more glycosides had enhanced effects.

Effects of letrozole on breast cancer micro-metastatic tumor growth in bone and lung in mice inoculated with murine 4T1 cells.

Breast cancer (BC) is the leading cancer in women worldwide. Metastasis occurs in stage IV BC with bone and lung being common metastatic sites. Here we evaluate the effects of the aromatase inhibitor letrozole on BC micro-metastatic tumor growth in bone and lung metastasis in intact and ovariectomized (OVX) mice with murine estrogen receptor negative (ER-) BC cells inoculated in tibia. Forty-eight BALB/c mice were randomly assigned to one of four groups: OVX, OVX + Letrozole, Intact, and Intact + Letrozole, and injected with 4T1 cells intra-tibially. Letrozole was subcutaneously injected daily for 23 days at a dose of 1.75 µg/g body weight. Tumor progression was monitored by bioluminescence imaging (BLI). Following necropsy, inoculated tibiae were scanned via µCT and bone response to tumor was scored from 0 (no ectopic mineralization/osteolysis) to 5 (extensive ectopic mineralization/osteolysis). OVX mice had higher tibial pathology scores indicative of more extensive bone destruction than intact mice, irrespective of letrozole treatment. Letrozole decreased serum estradiol levels and reduced lung surface tumor numbers in intact animals. Furthermore, mice receiving letrozole had significantly fewer tumor colonies and fewer proliferative cells in the lung than OVX and intact controls based on H&E and Ki-67 staining, respectively. In conclusion, BC-inoculated OVX animals had higher tibia pathology scores than BC-inoculated intact animals and letrozole reduced BC metastases to lungs. These findings suggest that, by lowering systemic estrogen level and/or by interacting with the host organ, the aromatase inhibitor letrozole has the potential to reduce ER- BC metastasis to lung.

Dietary soy isoflavones increase metastasis to lungs in an experimental model of breast cancer with bone micro-tumors.

Bone is one of the most common sites for metastasis in breast cancer (BC). Micro-metastasis in bone marrow was detected in 30% of patients with stage I, II, or III BC at primary surgery and is a strong indicator of poor prognosis. The role dietary soy isoflavones play in BC with bone micro-metastasis is unclear. In this study, we examined the effects of genistein, daidzein, (-)-equol or a mixture of soy isoflavones on BC with bone micro-metastasis using an experimental model of murine mammary cancer 4T1 cells engineered with luciferase. A small number (1000) of 4T1 cells were injected into the tibia of female Balb/c mice to establish micro-tumors in bone. Soy isoflavones were supplemented in the AIN-93G diet at 750 mg/kg and were provided to mice from 3 weeks before to 3 weeks after cell injection. Bioluminescent imaging was conducted on day 2 (D2), D6, D8, D16 and D20 post cell injection and the results indicated dietary soy isoflavones enhanced the growth of bone micro-tumors on D8. Furthermore, dietary soy isoflavones stimulated metastatic tumor formation in lungs and increased Ki-67 protein expression in these metastasized tumors. In vitro, soy isoflavones (<10 µM) had limited effects on the growth, motility or invasion of 4T1 cells. Thus, the in vivo stimulatory effect could be likely due to systemic effects between the host, 4T1 tumors and soy isoflavones. In conclusion, soy isoflavones stimulate BC with bone micro-metastasis in mice and further investigations are needed regarding their consumption by BC survivors.