Understanding early experiences of Chinese frontline nurses during the COVID-19 pandemic: A text mining and thematic analysis of social media information.

This study aims to explore the early experiences of frontline nurses at the beginning of the COVID-19 pandemic in China as expressed through social media posts. This study used an explanatory sequential mixed-method design. Text mining was used for sentiment analysis. The chi-square test was used to compare the differences in the composition ratio of sentiment classification of posts in different months. Word frequency was statistically analyzed. Further thematic analysis was also performed. The primary sentiments of the posts were discovered to be positive and neutral. The number of posts containing positive emotions was the lowest in January, peaked in March, and gradually declined in April 2020. The following nurse-oriented narrative themes were developed: "To see and be seen," "Moving forward amid adversity and support," and "Returning to everyday life and constructing meaning." The sentiments of Chinese nurses in response to the pandemic fluctuated, with positive emotions in the early stage, but it could not be sustained. This study recommends nurses could be encouraged to engage in expressive writing while adhering to ethical guidelines.

Experience of clinical nurses engaged in caring for patients with COVID-19: A qualitative systematic review and meta-synthesis.

AIMS AND OBJECTIVE: This qualitative review summarises and synthesises the available evidence on subjective experiences of clinical nurses who cared for patients with COVID-19. BACKGROUND: Nurses are first responders and play a vital role in emerging infectious disease epidemics such as the COVID-19 pandemic. In this context, they also face many difficulties and challenges related, for example to the imbalance between extensive demands and low control over work tasks. DESIGN AND METHOD: A systematic review of qualitative studies and meta-synthesis focused on the experiences of clinical nurses caring for patients with COVID-19 during the pandemic was carried out. RESULTS: A total of 279 findings were extracted, aggregated into 21 categories and combined into seven synthesised findings, namely (1) professional nursing practice during the pandemic, (2) support systems, (3) somatic sensations and psychological experiences, (4) difficulties and challenges, (5) coping strategies and behaviour, (6) impact on life, profession and values, and (7) needs and expectations for the future. CONCLUSION: Nurses encountered considerable difficulties and challenges in caring for patients with COVID-19. Nurses caring for patients with COVID-19 need more support from organisations, families and society. It is essential to explore positive coping strategies suitable for working in different cultural backgrounds. Policymakers and decision-makers should pay attention to the experiences and voices of nurses. RELEVANCE TO CLINICAL PRACTICE: It is critical for nurse managers to consider how to enhance the support system and help nurses develop adaptive coping strategies in response to COVID-19. Nurses' experiences and voices are valuable in improving health emergency response systems. PATIENT OR PUBLIC CONTRIBUTION: There was no patient or public contribution.

Changes in glycaemic control of oral anti-diabetic medications assessed by continuous glucose monitors among patients with type 2 diabetes: a protocol of network meta-analysis.

BACKGROUND: Continuous glucose monitors (CGMs) can measure interstitial fluid glucose levels to provide comprehensive real-time glucose profile among people with type 2 diabetes. These can accurately detect glucose levels, hyperglycaemia and hypoglycaemia events compared with conventional self-monitoring. Increased application of CGMs provides a valuable opportunity to evaluate glucose control on oral anti-diabetic medications. This review will compare the efficacy and safety of oral anti-diabetic medications among patients with type 2 diabetes, evaluated by CGM. METHODS: The following databases will be searched: Cochrane Library, PubMed, EMBASE, CINAHL, PsycINFO, Scopus and grey literature (ClinicalTrials.gov, PsycEXTRA, ProQuest Dissertations, Google Scholar and Theses Global) for the identification of studies. The review will include and summarise evidence from randomised clinical trials that use CGMs for blood glucose management in adults (aged ≥ 18 years), published in English between January 2000 and May 2021 without any restrictions of countries. Reference list of all selected articles will independently be screened to identify additional studies left out in the initial search. Primary outcomes will be HbA1c (≤ 7.0%), time spent with hypoglycaemia (< 70 mg/dl) or hyperglycaemia (≥ 180 mg/dl). Secondary outcomes will be change in weight, blood pressure and related comorbidities (cardiovascular mortality, heart failure events, myocardial infarction and stroke). Study selection, data extraction and quality assessment will be conducted independently by at least two reviewers. A third reviewer will determine and resolve discrepancies. At least two independent reviewers will cross-check data synthesis. The quality of evidence of the review will be assessed according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) Tool. DISCUSSION: The review is anticipated to provide up to date evidence for further studies and clinic practices regarding glycaemic control, hypoglycaemia, and hyperglycaemia issues. The results will be published in a peer-reviewed journal. TRIAL REGISTRATION: PROSPERO CRD42020188399 .

Chronologically modified androgen receptor in recurrent castration-resistant prostate cancer and its therapeutic targeting.

Resistance to second-generation androgen receptor (AR) antagonists such as enzalutamide is an inevitable consequence in patients with castration-resistant prostate cancer (CRPC). There are no effective therapeutic options for this recurrent disease. The expression of truncated AR variant 7 (AR-V7) has been suggested to be one mechanism of resistance; however, its low frequency in patients with CRPC does not explain the almost universal acquisition of resistance. We noted that the ability of AR to translocate to nucleus in an enzalutamide-rich environment opens up the possibility of a posttranslational modification in AR that is refractory to enzalutamide binding. Chemical proteomics in enzalutamide-resistant CRPC cells revealed acetylation at Lys609 in the zinc finger DNA binding domain of AR (acK609-AR) that not only allowed AR translocation but also galvanized a distinct global transcription program, conferring enzalutamide insensitivity. Mechanistically, acK609-AR was recruited to the AR and ACK1/TNK2 enhancers, up-regulating their transcription. ACK1 kinase-mediated AR Y267 phosphorylation was a prerequisite for AR K609 acetylation, which spawned positive feedback loops at both the transcriptional and posttranslational level that regenerated and sustained high AR and ACK1 expression. Consistent with these findings, oral and subcutaneous treatment with ACK1 small-molecule inhibitor, (R)-9b, not only curbed AR Y267 phosphorylation and subsequent K609 acetylation but also compromised enzalutamide-resistant CRPC xenograft tumor growth in mice. Overall, these data uncover chronological modification events in AR that allows prostate cancer to evolve through progressive stages to reach the resilient recurrent CRPC stage, opening up a therapeutic vulnerability.

The non-canonical target PARP16 contributes to polypharmacology of the PARP inhibitor talazoparib and its synergy with WEE1 inhibitors.

PARP inhibitors (PARPis) display single-agent anticancer activity in small cell lung cancer (SCLC) and other neuroendocrine tumors independent of BRCA1/2 mutations. Here, we determine the differential efficacy of multiple clinical PARPis in SCLC cells. Compared with the other PARPis rucaparib, olaparib, and niraparib, talazoparib displays the highest potency across SCLC, including SLFN11-negative cells. Chemical proteomics identifies PARP16 as a unique talazoparib target in addition to PARP1. Silencing PARP16 significantly reduces cell survival, particularly in combination with PARP1 inhibition. Drug combination screening reveals talazoparib synergy with the WEE1/PLK1 inhibitor adavosertib. Global phosphoproteomics identifies disparate effects on cell-cycle and DNA damage signaling thereby illustrating underlying mechanisms of synergy, which is more pronounced for talazoparib than olaparib. Notably, silencing PARP16 further reduces cell survival in combination with olaparib and adavosertib. Together, these data suggest that PARP16 contributes to talazoparib's overall mechanism of action and constitutes an actionable target in SCLC.

Barriers and facilitators of diabetes management by continuous glucose monitoring systems among adults with type 2 diabetes: a protocol of qualitative systematic review.

INTRODUCTION: Studies suggest that continuous glucose monitors (CGMs) play an important role in the management of diabetes. Although general acceptance has been reported by patients with type 2 diabetes towards the use of CGMs, potential barriers exist like pain due to sensor insertion, accidental removal of the device or adhesive strip, impacts of daily activities, skin reactions to sensor adhesive, etc. This systematic review of qualitative studies aims to explore the perspectives, experiences and narratives of patients and caregivers about CGM use, and its barriers and facilitators. METHODS AND ANALYSIS: This review will include qualitative studies and cross-sectional and longitudinal cohort studies using open-ended questions, published in English by 30 October 2021. The following electronic databases will be searched: Cochrane Library, PubMed, EMBASE, CINAHL, PsycINFO and Scopus. A search of grey literature will be conducted via an online search of Google Scholar, WorldCat, ClinicalTrials.gov and OpenGrey A combined search strategy using medical subject headings (MeSH), controlled vocabulary and 'free-text' terms will be appropriately revised to suit each database. Primary outcomes will include patient and caregiver perspectives on diabetes management regarding glucose control; living with CGM (quality of life, experience of wearing a CGM); psychological aspects (anxiety, depression, emotional burden); barriers (technical issues, financial issues) to use of CGM and thoughts (interpretation, understanding) on the CGM report. A qualitative meta-synthesis will be conducted employing a systematic literature search of existing literature, quality assessment using study-specific tools and an aggregative thematic synthesis by a multidisciplinary team. ETHICS AND DISSEMINATION: Ethical approval is not required since this is a systematic review. The results will help improve clinical implementation of CGMs on part of both patients and caregivers. PROSPERO REGISTRATION NUMBER: CRD42020152211.

Willingness to participate in front-line work during the COVID-19 pandemic: A cross-sectional study of nurses from a province in South-West China.

AIM: To explore the current status of Chinese nurses' willingness to work during the COVID-19 pandemic and the factors that influence them. BACKGROUND: The demand for front-line nurses continues to grow during the COVID-19 pandemic, but their willingness varies significantly. Therefore, it is crucial to explore nurses' willingness to report for front-line work. METHODS: A cross-sectional study of 1,310 nurses from six tertiary hospitals was conducted. The participants completed self-administered online questionnaires. RESULTS: A total of 90.5% of nurses reported that they would like to voluntarily participate in front-line work. Those with previous training, higher self-efficacy scores, and lower perceived risk and self-worth scores were more likely to participate in front-line work, while nurses, who had 11-15 years of work experience and were worried about their family and the lack of family support, were less likely to be involved in front-line work. CONCLUSION: This study found that the vast majority of nurses were willing to participate in front-line work and affirmed the positive effects of previous infection prevention training, self-efficacy and self-worth. IMPLICATIONS FOR NURSING MANAGEMENT: This research emphasizes the necessity of infection prevention training and provides evidence for further emergency workforce deployment and incentives.

Comparing effects of continuous glucose monitoring systems (CGMs) and self-monitoring of blood glucose (SMBG) amongst adults with type 2 diabetes mellitus: a systematic review protocol.

BACKGROUND: Continuous glucose monitorings (CGMs) have been used to manage diabetes with reasonable glucose control amongst patients with type 2 diabetes (T2D) in recent decades. CGMs measure interstitial fluid glucose levels to provide information about glucose levels, which identify fluctuation that would not have been identified with conventional self-monitoring. Self-monitoring of blood glucose (SMBG) is a classical tool to measure glycaemic changes. However, the effectiveness of glucose control, hypoglycemia, weight change, quality of life and user satisfaction, are needed to evaluate and compare CGMs and SMBG amongst adults with T2D. METHODS: The review will compare the various forms of CGM systems (i.e flash CGM, real-time CGM, retrospective CGM) versus SMBG or usual intervention regarding diabetes management amongst adults with T2D. The following databases will be searched: Cochrane Library, PubMed, EMBASE, CINAHL, PsycINFO, Scopus and grey literature (ClinicalTrials.gov, PsycEXTRA, ProQuest Dissertations, Google Scholar and Theses Global) for the identification of studies. The studies involving adults (aged ≥ 18 years old) will be included. We will only include and summarise randomised clinical trials (RCTs) with respect to authors, publication type, year, status and type of devices. Studies published in English between February 2010 and March 2020, will be included as the field of CGMs amongst T2D patients has emerged over the last decade. Primary outcomes will be HbA1c (glycosylated haemoglobin level) (mmol/L), body weight (kg), time spent with hypoglycaemia (< 70 mg/dl) or hyperglycaemia (≥ 180 mg/dl), blood pressure (< 140/90 mmHg is considered as good management) and quality of life (understanding and feeling of living situation based on culture and value system). Secondary outcome measures will be user satisfaction (patient or treatment/intervention satisfaction or satisfaction scale) and barriers (physical and mental difficulties or issues). Study selection, data extraction and risk of bias assessment will be conducted independently by at least two reviewers. A third reviewer will determine and resolve discrepancies. Moreover, the quality of the evidence of the review will be assessed according to the Grading of Recommendations Assessment, Development and Evaluation tool (GRADE). DISCUSSION: The review will synthesise evidence on the comparison between using CGMs and SMBG. The results will support researchers and health professionals to determine the most effective methods/technologies in the overall diabetes management. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42020149212.

[Effects on vibration perception threshold and the quality of life in the patients of high-risk diabetic foot treated with the pestle needling therapy].

OBJECTIVE: To evaluate the effects of the pestle needling therapy on the vibration perception threshold (VPT) and the quality of life (QOL) in the patients of high-risk diabetic foot. METHODS: A total of 132 patients of high risk diabetic foot were randomized into an observation group and a control group, 66 cases in each one. In the control group, the routine treatment and nursing for diabetes were applied. In the observation group, on the base of the treatment as the control group, the pestle needling therapy was used at Zhiyangbazhen, Mingmenbazhen, Hechemingqiangduan, Zusanli (ST 36), Yongquan (KI 1), Sanyinjiao (SP 6) and Taixi (KI 3). The intervention with the pestle needling therapy was given once every day, consecutively for 4 weeks. The follow-up visit was conducted in 3 months and 6 months after the intervention. Vibration perception threshold (VPT) was observed before and after intervention in the two groups. Separately, before intervention, at the end of intervention, 3 months after intervention and 6 months after intervention, the type 2 diabetes mellitus quality life scale (DMQLS), the revised edition was adopted to compare the QOL between the two groups. The effects were evaluated in the two groups. RESULTS: After intervention, the VPT and QOL were all improved in the two groups (P<0.01, P<0.05). In the observation group, after intervention, VPT at the first toes and the dorsum of the feet was lower than the control group at the same time point (all P<0.01). In the observation group, the total scores and the score of each dimension item in the DMQLS of the revised edition were all lower than the control group correspondently at the end of intervention, 3 months after intervention and 6 months after intervention (P<0.01, P<0.05). The repeated ANOVA results showed that the differences were significant in the total scores and the score of each dimension in the aspects of time, inter-group and interaction effect (P<0.01, P<0.05). The total scores and score of each dimension item in the DMQLS were lower than those the earlier time point (P<0.01, P<0.05). The total effective rate was 100.0% in the observation group, which was superior to 95.1% (59/62) in the control group (P<0.05). CONCLUSION: The pestle needling therapy reduces the foot VPT and improves the sensory nerve function of the foot and the QOL in the patients of high-risk diabetic foot.

Dabrafenib inhibits the growth of BRAF-WT cancers through CDK16 and NEK9 inhibition.

Although the BRAF inhibitors dabrafenib and vemurafenib have both proven successful against BRAF-mutant melanoma, there seem to be differences in their mechanisms of action. Here, we show that dabrafenib is more effective at inhibiting the growth of NRAS-mutant and KRAS-mutant cancer cell lines than vemurafenib. Using mass spectrometry-based chemical proteomics, we identified NEK9 and CDK16 as unique targets of dabrafenib. Both NEK9 and CDK16 were highly expressed in specimens of advanced melanoma, with high expression of both proteins correlating with a worse overall survival. A role for NEK9 in the growth of NRAS- and KRAS-mutant cell lines was suggested by siRNA studies in which silencing was associated with decreased proliferation, cell cycle arrest associated with increased p21 expression, inhibition of phospho-CHK1, decreased CDK4 expression, and the initiation of a senescence response. Inhibition of CDK4 but not CHK1 recapitulated the effects of NEK9 silencing, indicating this to be the likely mechanism of growth inhibition. We next turned our attention to CDK16 and found that its knockdown inhibited the phosphorylation of the Rb protein at S780 and increased expression of p27. Both of these effects were phenocopied in NRAS- and KRAS-mutant cancer cells by dabrafenib, but not vemurafenib. Combined silencing of NEK9 and CDK16 was associated with enhanced inhibition of melanoma cell proliferation. In summary, we have identified dabrafenib as a potent inhibitor of NEK9 and CDK16, and our studies suggest that inhibition of these kinases may have activity against cancers that do not harbor BRAF mutations.

Dual Targeting of WEE1 and PLK1 by AZD1775 Elicits Single Agent Cellular Anticancer Activity.

Inhibition of the WEE1 tyrosine kinase enhances anticancer chemotherapy efficacy. Accordingly, the WEE1 inhibitor AZD1775 (previously MK-1775) is currently under evaluation in clinical trials for cancer in combination with chemotherapy. AZD1775 has been reported to display high selectivity and is therefore used in many studies as a probe to interrogate WEE1 biology. However, AZD1775 also exhibits anticancer activity as a single agent although the underlying mechanism is not fully understood. Using a chemical proteomics approach, we here describe a proteome-wide survey of AZD1775 targets in lung cancer cells and identify several previously unknown targets in addition to WEE1. In particular, we observed polo-like kinase 1 (PLK1) as a new target of AZD1775. Importantly, in vitro kinase assays showed PLK1 and WEE1 to be inhibited by AZD1775 with similar potency. Subsequent loss-of-function experiments using RNAi for WEE1 and PLK1 suggested that targeting PLK1 enhances the pro-apoptotic and antiproliferative effects observed with WEE1 knockdown. Combination of RNAi with AZD1775 treatment suggested WEE1 and PLK1 to be the most relevant targets for mediating AZD1775's anticancer effects. Furthermore, disruption of WEE1 by CRISPR-Cas9 sensitized H322 lung cancer cells to AZD1775 to a similar extent as the potent PLK1 inhibitor BI-2536 suggesting a complex crosstalk between PLK1 and WEE1. In summary, we show that AZD1775 is a potent dual WEE1 and PLK1 inhibitor, which limits its use as a specific molecular probe for WEE1. However, PLK1 inhibition makes important contributions to the single agent mechanism of action of AZD1775 and enhances its anticancer effects.

Proteome-wide Profiling of Clinical PARP Inhibitors Reveals Compound-Specific Secondary Targets.

Poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi) are a promising class of targeted cancer drugs, but their individual target profiles beyond the PARP family, which could result in differential clinical use or toxicity, are unknown. Using an unbiased, mass spectrometry-based chemical proteomics approach, we generated a comparative proteome-wide target map of the four clinical PARPi, olaparib, veliparib, niraparib, and rucaparib. PARPi as a class displayed high target selectivity. However, in addition to the canonical targets PARP1, PARP2, and several of their binding partners, we also identified hexose-6-phosphate dehydrogenase (H6PD) and deoxycytidine kinase (DCK) as previously unrecognized targets of rucaparib and niraparib, respectively. Subsequent functional validation suggested that inhibition of DCK by niraparib could have detrimental effects when combined with nucleoside analog pro-drugs. H6PD silencing can cause apoptosis and further sensitize cells to PARPi, suggesting that H6PD may be, in addition to its established role in metabolic disorders, a new anticancer target.

[Copracrasia treated with acupuncture and moxibustion: a randomized controlled trial].

OBJECTIVE: To explore the clinical efficacy and safety of acupuncture and moxibustion for copracrasia. METHODS: By prospective live randomized controlled trial, 40 cases with copracrasia were randomly divided into an acupuncture-moxibustion group and a medication group, 20 cases in each one. In the acupuncture-moxibustion group, acupuncture was applied at Ciliao (BL 32), Changqiang (GV 1) and Tianshu (ST 25) and mild moxibustion was used at Qihai (CV 6). Treatment was given for 12 weeks and 32 times, 3 times a week in the front 8 weeks, 2 times a week in the latter 4 weeks. In the medication group, conventional symptomatic treatment, support therapy, and complications preventing and treating were adopted for 12 weeks. Anal incontinence score (Vaizey incontinence score), effective rate and self-rating score for satisfaction were observed before and after treatment and in the follow-up period. RESULTS: After 12 weeks' treatment in the two groups, Vaizey incontinence' scores were both decreased (both P<0. 05), and after treatment and in the follow-up period the scores in the acupuncture-moxibustion group were lower than those in the corresponding period in the medication group (both P< 0. 05). The effective rate of the acupuncture-moxibustion group was 80. 0% (16/20), which was statistically different from 50. 0% (10/20) in the medication group (P<0. 05). The effective rate in the follow-up period of the acupuncture-moxibustion group was 90. 0% (18/20) and it was not statistically different from 80. 0% (16/20) in the medication group (P>0. 05). The self-rating scores for satisfaction in the acupuncture-moxibustion group were superior to those in the medication group after treatment and in the follow-up period (both P< 0. 05). CONCLUSION: Acupuncture and moxibustion could improve copracrasia and the acupuncture-moxibustion rules and characteristics for the disorder should be paid attention to in the further research.

Development of novel ACK1/TNK2 inhibitors using a fragment-based approach.

The tyrosine kinase ACK1, a critical signal transducer regulating survival of hormone-refractory cancers, is an important therapeutic target, for which there are no selective inhibitors in clinical trials to date. This work reports the discovery of novel and potent inhibitors for ACK1 tyrosine kinase (also known as TNK2) using an innovative fragment-based approach. Focused libraries were designed and synthesized by selecting fragments from reported ACK inhibitors to create hybrid structures in a mix and match process. The hybrid library was screened by enzyme-linked immunosorbent assay-based kinase inhibition and (33)P HotSpot assays. Systematic structure-activity relationship studies led to the identification of compound (R)-9b, which shows potent in vitro (IC50 = 56 nM, n = 3, (33)P HotSpot assay) and in vivo (IC50 < 2 µM, human cancer cell lines) ACK1 inhibition. Both (R)-9b and (S)-9b were stable in human plasma and displayed a long half-life (t(1/2) > 6 h).

Dual Aurora A and JAK2 kinase blockade effectively suppresses malignant transformation.

Aurora A and JAK2 kinases are involved in cell division and tumor cell survival, respectively. Here we demonstrate that ectopic expression of Aurora A and JAK2 together is more effective than each alone at inducing non-transformed cells to grow in an anchorage-independent manner and to invade. Furthermore, siRNA silencing or pharmacological inhibition of Aurora A and JAK2 with Alisertib and Ruxolitinib, respectively, is more effective than blocking each kinase alone at suppressing anchorage-dependent and -independent growth and invasion as well as at inducing apoptosis. Importantly, we have developed dual Aurora and JAK inhibitors, AJI-214 and AJI-100, which potently inhibit Aurora A, Aurora B and JAK2 in vitro. In human cancer cells, these dual inhibitors block the auto-phosphorylation of Aurora A (Thr-288) and the phosphorylation of the Aurora B substrate histone H3 (Ser-10) and the JAK2 substrate STAT3 (Tyr-705). Furthermore, AJI-214 and AJI-100 inhibit anchorage dependent and independent cell growth and invasion and induce G2/M cell cycle accumulation and apoptosis. Finally, AJI-100 caused regression of human tumor xenografts in mice. Taken together, our genetic and pharmacological studies indicate that targeting Aurora A and JAK2 together is a more effective approach than each kinase alone at inhibiting malignant transformation and warrant further advanced pre clinical investigations of dual Aurora A/JAK2 inhibitors as potential anti tumor agents.

GSK3 alpha and beta are new functionally relevant targets of tivantinib in lung cancer cells.

Tivantinib has been described as a potent and highly selective inhibitor of the receptor tyrosine kinase c-MET and is currently in advanced clinical development for several cancers including non-small cell lung cancer (NSCLC). However, recent studies suggest that tivantinib's anticancer properties are unrelated to c-MET inhibition. Consistently, in determining tivantinib's activity profile in a broad panel of NSCLC cell lines, we found that, in contrast to several more potent c-MET inhibitors, tivantinib reduces cell viability across most of these cell lines. Applying an unbiased, mass-spectrometry-based, chemical proteomics approach, we identified glycogen synthase kinase 3 (GSK3) alpha and beta as novel tivantinib targets. Subsequent validation showed that tivantinib displayed higher potency for GSK3α than for GSK3ß and that pharmacological inhibition or simultaneous siRNA-mediated loss of GSK3α and GSK3ß caused apoptosis. In summary, GSK3α and GSK3ß are new kinase targets of tivantinib that play an important role in its cellular mechanism-of-action in NSCLC.

Development of o-chlorophenyl substituted pyrimidines as exceptionally potent aurora kinase inhibitors.

The o-carboxylic acid substituted bisanilinopyrimidine 1 was identified as a potent hit (Aurora A IC(50) = 6.1 ± 1.0 nM) from in-house screening. Detailed structure-activity relationship (SAR) studies indicated that polar substituents at the para position of the B-ring are critical for potent activity. X-ray crystallography studies revealed that compound 1 is a type I inhibitor that binds the Aurora kinase active site in a DFG-in conformation. Structure-activity guided replacement of the A-ring carboxylic acid with halogens and incorporation of fluorine at the pyrimidine 5-position led to highly potent inhibitors of Aurora A that bind in a DFG-out conformation. B-Ring modifications were undertaken to improve the solubility and cell permeability. Compounds such as 9m with water-solubilizing moieties at the para position of the B-ring inhibited the autophosphorylation of Aurora A in MDA-MB-468 breast cancer cells.

Discovery and synthesis of hydronaphthoquinones as novel proteasome inhibitors.

Screening efforts led to the identification of PI-8182 (1), an inhibitor of the chymotrypsin-like (CT-L) activity of the proteasome. Compound 1 contains a hydronaphthoquinone pharmacophore with a thioglycolic acid side chain at position 2 and thiophene sulfonamide at position 4. An efficient synthetic route to the hydronaphthoquinone sulfonamide scaffold was developed, and compound 1 was synthesized in-house to confirm the structure and activity (IC(50) = 3.0 ± 1.6 µM [n = 25]). Novel hydronaphthoquinone derivatives of 1 were designed, synthesized, and evaluated as proteasome inhibitors. The structure-activity relationship (SAR) guided synthesis of more than 170 derivatives revealed that the thioglycolic acid side chain is required and the carboxylic acid group of this side chain is critical to the CT-L inhibitory activity of compound 1. Furthermore, replacement of the carboxylic acid with carboxylic acid isosteres such as tetrazole or triazole greatly improves potency. Compounds with a thio-tetrazole or thio-triazole side chain in position 2, where the thiophene was replaced by hydrophobic aryl moieties, were the most active compounds with up to 20-fold greater CT-L inhibition than compound 1 (compounds 15e, 15f, 15h, 15j, IC(50) values around 200 nM, and compound 29, IC(50) = 150 nM). The synthetic iterations described here not only led to improving potency in vitro but also resulted in the identification of compounds that are more active such as 39 (IC(50) = 0.44 to 1.01 µM) than 1 (IC(50) = 3.54 to 7.22 µM) at inhibiting the proteasome CT-L activity in intact breast cancer cells. Treatment with 39 also resulted in the accumulation of ubiquitinated cellular proteins and inhibition of tumor cell proliferation of breast cancer cells. The hit 1 and its analogue 39 inhibited proteasome CT-L activity irreversibly.

A novel mechanism by which small molecule inhibitors induce the DFG flip in Aurora A.

Most protein kinases share a DFG (Asp-Phe-Gly) motif in the ATP site that can assume two distinct conformations, the active DFG-in and the inactive DFG-out states. Small molecule inhibitors able to induce the DFG-out state have received considerable attention in kinase drug discovery. Using a typical DFG-in inhibitor scaffold of Aurora A, a kinase involved in the regulation of cell division, we found that halogen and nitrile substituents directed at the N-terminally flanking residue Ala273 induced global conformational changes in the enzyme, leading to DFG-out inhibitors that are among the most potent Aurora A inhibitors reported to date. The data suggest an unprecedented mechanism of action, in which induced-dipole forces along the Ala273 side chain alter the charge distribution of the DFG backbone, allowing the DFG to unwind. As the ADFG sequence and three-dimensional structure is highly conserved, DFG-out inhibitors of other kinases may be designed by specifically targeting the flanking alanine residue with electric dipoles.

Synthesis and biological evaluation of naphthoquinone analogs as a novel class of proteasome inhibitors.

Screening of the NCI Diversity Set-1 identified PI-083 (NSC-45382) a proteasome inhibitor selective for cancer over normal cells. Focused libraries of novel compounds based on PI-083 chloronaphthoquinone and sulfonamide moieties were synthesized to gain a better understanding of the structure-activity relationship responsible for chymotrypsin-like proteasome inhibitory activity. This led to the demonstration that the chloronaphthoquinone and the sulfonamide moieties are critical for inhibitory activity. The pyridyl group in PI-083 can be replaced with other heterocyclic groups without significant loss of activity. Molecular modeling studies were also performed to explore the detailed interactions of PI-083 and its derivatives with the beta5 and beta6 subunits of the 20S proteasome. The refined model showed an H-bond interaction between the Asp-114 and the sulfonamide moiety of the PI-083 in the beta6 subunit.