Discovery of pyrrolo[2,3-d]pyrimidin-4-one derivative YCH3124 as a potent USP7 inhibitor for cancer therapy.

USP7 is one of the most studied deubiquitinating enzymes, which is involved in the regulation of multiple cell signaling pathways and has been shown to be associated with the occurrence and progression of a variety of cancers. Inhibitors targeting USP7 have been studied by several teams, but most of them lack selectivity and have low activities. Herein, we reported a serious of pyrrole[2,3-d]pyrimidin-4-one derivatives through scaffold hopping of recently reported 4-hydroxypiperidine compounds. The representative compound Z33 (YCH3124) exhibited highly potent USP7 inhibition activity as well as anti-proliferative activity against four kinds of cancer cell lines. Further study revealed that YCH3124 effectively inhibited the downstream USP7 pathway and resulted in the accumulation of both p53 and p21 in a dose-dependent manner. Notably, YCH3124 disrupted cell cycle progression through restricting G1 phase and induced significant apoptosis in CHP-212 cells. In summary, our efforts provided a series of novel pyrrole[2,3-d]pyrimidin-4-one analogs as potent USP7 inhibitors with excellent anti-cancer activity.

Zinc as a potential regulator of the BCR-ABL oncogene in chronic myelocytic leukemia cells.

BACKGROUND: Generally, decreased zinc in the serum of tumor patients but increased zinc in tumor cells can be observed. However, the role of zinc homeostasis in myeloid leukemia remains elusive. BCR-ABL is essential for the initiation, maintenance, and progression of chronic myelocytic leukemia (CML). We are currently investigating the association between zinc homeostasis and CML. METHODS: Genes involved in zinc homeostasis were examined using three GEO datasets. Western blotting and qPCR were used to investigate the effects of zinc depletion on BCR-ABL expression. Furthermore, the effect of TPEN on BCR-ABL promoter activity was determined using the dual-luciferase reporter assay. MRNA stability and protein stability of BCR-ABL were assessed using actinomycin D and cycloheximide. RESULTS: Transcriptome data mining revealed that zinc homeostasis-related genes were associated with CML progression and drug resistance. Several zinc homeostasis genes were affected by TPEN. Additionally, we found that zinc depletion by TPEN decreased BCR-ABL mRNA stability and transcriptional activity in K562 CML cells. Zinc supplementation and sodium nitroprusside treatment reversed BCR-ABL downregulation by TPEN, suggesting zinc- and nitric oxide-dependent mechanisms. CONCLUSION: Our in vitro findings may help to understand the role of zinc homeostasis in BCR-ABL regulation and thus highlight the importance of zinc homeostasis in CML.

Identification of YCH2823 as a novel USP7 inhibitor for cancer therapy.

Inhibition of the human ubiquitin-specific protease 7 (USP7), the key deubiquitylating enzyme in regulating p53 protein levels, has been considered an attractive anticancer strategy. In order to enhance the cellular activity of FT671, scaffold hopping strategy was employed. This endeavor resulted in the discovery of YCH2823, a novel and potent USP7 inhibitor.YCH2823 demonstrated remarkable efficacy in inhibiting the growth of a specific subset of TP53 wild-type, -mutant, and MYCN-amplified cell lines, surpassing the potency of FT671 by approximately 5-fold. The mechanism of action of YCH2823 involves direct interaction with the catalytic domain of USP7, thereby impeding the cleavage of ubiquitinated substrates. An increase in the expression of p53 and p21, accompanied by G1 phase arrest and apoptosis, was observed upon treatment with YCH2823. Subsequently, the knockdown of p53 or p21 in CHP-212 cells exhibited a substantial reduction in sensitivity to YCH2823, as evidenced by a considerable increase in IC50 values up to 690-fold. Furthermore, YCH2823 treatment specifically enhanced the transcriptional and protein levels of BCL6 in sensitive cells. Moreover, a synergistic effect between USP7 inhibitors and mTOR inhibitors was observed, suggesting the possibility of novel therapeutic strategies for cancer treatment. In conclusion, YCH2823 exhibits potential as an anticancer agent for the treatment of both TP53 wild-type and -mutant tumors.

YCH1899, a Highly Effective Phthalazin-1(2H)-one Derivative That Overcomes Resistance to Prior PARP Inhibitors.

Poly(ADP-ribose) polymerase inhibitors (PARPi) have significant efficacy in treating BRCA-deficient cancers, although resistance development remains an unsolved challenge. Herein, a series of phthalazin-1(2H)-one derivatives with excellent enzymatic inhibitory activity were designed and synthesized, and the structure-activity relationship was explored. Compared with olaparib and talazoparib, compound YCH1899 exhibited distinct antiproliferation activity against olaparib- and talazoparib-resistant cells, with IC50 values of 0.89 and 1.13 nM, respectively. Studies of the cellular mechanism revealed that YCH1899 retained sensitivity in drug-resistant cells with BRCA1/2 restoration or 53BP1 loss. Furthermore, YCH1899 had acceptable pharmacokinetic properties in rats and showed prominent dose-dependent antitumor activity in olaparib- and talazoparib-resistant cell-derived xenograft models. Overall, this study suggests that YCH1899 is a new-generation antiresistant PARPi that could provide a valuable direction for addressing drug resistance to existing PARPi drugs.

Zinc depletion induces JNK/p38 phosphorylation and suppresses Akt/mTOR expression in acute promyelocytic NB4 cells.

BACKGROUND: Myeloid leukemia is associated with reduced serum zinc and increased intracellular zinc. Our previous studies found that zinc depletion by TPEN induced apoptosis with PML-RARα oncoprotein degradation in acute promyelocytic NB4 cells. The effect of zinc homeostasis on intracellular signaling pathways in myeloid leukemia cells remains unclear. OBJECTIVE: This study examined how zinc homeostasis affected MAPK and Akt/mTOR pathways in NB4 cells. METHODS: We used western blotting to detect the activation of p38 MAPK, JNK, ERK1/2, and Akt/mTOR pathways in NB4 cells stimulated with the zinc chelator TPEN. Whether the effects of TPEN on these pathways could be reversed by zinc or the nitric oxide donor sodium nitroprusside (SNP) was further explored by western blotting. We used Zinpyr-1 staining to assess the role of SNP on labile zinc levels in NB4 cells treated with TPEN. In additional, we evaluated expressional correlations between the zinc-binding protein Metallothionein-2A (MT2A) and genes related to MAPKs and Akt/mTOR pathways in acute myeloid leukemia (AML) based on the TCGA database. RESULTS: Zinc depletion by TPEN activated p38 and JNK phosphorylation in NB4 cells, whereas ERK1/2 phosphorylation was increased first and then decreased. The protein expression levels of Akt and mTOR were downregulated by TPEN. The nitric oxide donor SNP promotes zinc release in NB4 cells under zinc depletion conditions. We further found that the effects of zinc depletion on MAPK and Akt/mTOR pathways in NB4 cells can be reversed by exogenous zinc supplementation or treatment with the nitric oxide donor SNP. By bioinformatics analyses based on the TCGA database, we demonstrated that MT2A expression was negatively correlated with the expression of JNK, and was positively correlated with the expression of ERK1 and Akt in AML. CONCLUSION: Our findings indicate that zinc plays a critical role in leukemia cells and help understanding how zinc depletion induces apoptosis.

Expression pattern and prognostic implication of zinc homeostasis-related genes in acute myeloid leukemia.

Zinc homeostasis is regulated by the SLC39A/ZIP, SLC30A/ZnT, and metallothionein (MT) protein families. The association of zinc homeostasis with acute myeloid leukemia (AML) is unclear. We previously demonstrated that zinc depletion by TPEN triggers apoptosis in NB4 AML cells with the degradation of PML-RARα oncoprotein, suggesting that zinc homeostasis may be associated with AML. The primary aim of this study was to explore the expression pattern and prognostic roles of zinc homeostasis-related genes in AML. Bioinformatics analyses were performed using integrated datasets from the TCGA and GTEx projects. The GEPIA tool was used to analyze the differential expression of zinc homeostasis-related genes. Correlations between zinc homeostasis-related genes were assessed with Spearman's correlation coefficient. OncoLnc was used to evaluate the prognostic roles of zinc homeostasis-related genes with Kaplan-Meier and Cox regression models. In both NB4 and U937 cells, the transcriptional regulation of zinc homeostasis-related genes by zinc depletion was detected through qPCR. We found that multiple ZIPs, ZnTs, and MTs were differentially expressed and correlated in AML tumors. In AML patients, higher expression of ZIP4 and lower expression of ZnT5 and ZnT7 predicted poorer survival. We further found that zinc depletion by TPEN upregulated ZIP7, ZIP9, ZIP10, ZIP13, and ZnT7 and downregulated ZIP14, ZnT1, ZnT6, and most of the positively expressed MTs in both NB4 and U937 AML cells. Our findings suggest high expression of ZIP4 and low expression of ZnT5 and ZnT7 as potential risk factors for the prognosis of AML. Zinc homeostasis may be a potential therapeutic target for AML, deserving further exploration.

Intact regulation of G1/S transition renders esophageal squamous cell carcinoma sensitive to PI3Kα inhibitors.

Phosphatidylinositol 3-kinase alpha (PI3Kα) inhibitors are currently evaluated for the therapy of esophageal squamous cell carcinoma (ESCC). It is of great importance to identify potential biomarkers to predict or monitor the efficacy of PI3Kα inhibitors in an aim to improve the clinical responsive rate in ESCC. Here, ESCC PDXs with CCND1 amplification were found to be more sensitive to CYH33, a novel PI3Kα-selective inhibitor currently in clinical trials for the treatment of advanced solid tumors including ESCC. Elevated level of cyclin D1, p21 and Rb was found in CYH33-sensitive ESCC cells compared to those in resistant cells. CYH33 significantly arrested sensitive cells but not resistant cells at G1 phase, which was associated with accumulation of p21 and suppression of Rb phosphorylation by CDK4/6 and CDK2. Hypo-phosphorylation of Rb attenuated the transcriptional activation of SKP2 by E2F1, which in turn hindered SKP2-mediated degradation of p21 and reinforced accumulation of p21. Moreover, CDK4/6 inhibitors sensitized resistant ESCC cells and PDXs to CYH33. These findings provided mechanistic rationale to evaluate PI3Kα inhibitors in ESCC patients harboring amplified CCND1 and the combined regimen with CDK4/6 inhibitors in ESCC with proficient Rb.

Lithium in Cancer Therapy: Friend or Foe?

Lithium, a trace element important for fetal health and development, is considered a metal drug with a well-established clinical regime, economical production process, and a mature storage system. Several studies have shown that lithium affects tumor development by regulating inositol monophosphate (IMPase) and glycogen synthase kinase-3 (GSK-3). Lithium can also promote proliferation and programmed cell death (PCD) in tumor cells through a number of new targets, such as the nuclear receptor NR4A1 and Hedgehog-Gli. Lithium may increase cancer treatment efficacy while reducing side effects, suggesting that it can be used as an adjunctive therapy. In this review, we summarize the effects of lithium on tumor progression and discuss the underlying mechanisms. Additionally, we discuss lithium's limitations in antitumor clinical applications, including its narrow therapeutic window and potential pro-cancer effects on the tumor immune system.

Synthesis and biological evaluation of pyrazole-fused oleanolic acid derivatives as novel inhibitors of inflammatory and osteoclast differentiation.

A series of pyrazole-fused oleanolic acid derivatives were designed and synthesized. The modification of these analogues focused on the substituents screening on the pyrazole ring. The cytotoxicity of these compounds and their anti-inflammatory activities via inhibiting interleukin-1ß (IL-1ß) production were evaluated in RAW264.7 cells. Most of the derivatives showed significantly improved potency compared with oleanolic acid. Among them, compound 7n exhibited the most potent anti-inflammatory activity on decreasing IL-1ß production with low cytotoxicity. Moreover, the further study found 7n could inhibit RANKL-induced osteoclast differentiation on bone marrow-derived macrophages (BMMs). These findings may provide a potential direction for the drug development of osteoarthritis.

Absorption, distribution, metabolism, and excretion of [14C]Mefuparib (CVL218), a novel PARP1/2 inhibitor, in rats.

INTRODUCTION: Mefuparib (CVL218) is a novel second-generation poly-ADP-ribose polymerase (PARP) inhibitor for cancer treatment. CVL218 can easily enter the brain. However, the transport mechanism by which CVL218 crosses the blood-brain barrier (BBB) is unknown. METHODS: (1) [14C] CVL218 metabolism in rats was traced by a liquid scintillation counter and oxidative combustion. (2) Metabolic profiles and metabolites were identified by UHPLC-ß-RAM/UHPLC-Fraction Collector and UHPLC-Q Exactive Plus MS. (3) The partition coefficient Kp,uu,brain value was simulated by two strategies. One strategy was using ACD and GastroPlus Software based on the results of intravenous administration pharmacokinetics and plasma protein-binding studies. The reliability was confirmed by comparison with another strategy (brain/plasma distribution study). RESULTS: (1) Rapid drug elimination was observed 24 h after intragastric administration. The total cumulative excretion in urine and feces within 168 h accounted for 97.15% of the dose. The cumulative radioactive dose recovery in bile was 41.87% within 72 h. The drug-related substances were extensively distributed to the tissues within 48 h. (2) M8 was the major metabolite in plasma, urine, feces and bile. (3) CVL218 exhibited high brain protein-binding rate (88.16%). The Kp,uu,brain value (8.42) simulated by the simple software strategy was similar to that of the brain/plasma distribution study (7.01). CONCLUSIONS: CVL218 is a fast-metabolizing drug and is mainly excreted in feces. The B/P ratio prediction and observation data for CVL218 were consistent. Furthermore, the Kp,uu,brain value indicated that penetration through the BBB might be mediated by uptake transporters.

Development of an Orally Active Small-Molecule Inhibitor of Receptor Activator of Nuclear Factor-κB Ligand.

Receptor activator of nuclear factor-κB (RANK) and its ligand, RANKL, play pivotal roles in bone remodeling. The monoclonal antibody denosumab successfully inhibited the maturation of osteoclasts (OCs) by binding to RANKL in the clinic. We continued our efforts to develop small-molecule inhibitors of RANKL. In this work, 41 ß-carboline derivatives were synthesized based on previously synthesized compound Y1599 to improve its drug-like properties. Compound Y1693 was identified as a potent RANKL inhibitor that improved absorption-distribution-metabolism-excretion properties and effectively prevented RANKL-induced osteoclastogenesis and bone resorption. Furthermore, Y1693 also suppressed the expression of OC marker genes. Moreover, Y1693 demonstrated good tolerability and efficacy in an orally administered mouse model of osteoporosis as well as the ability to rescue alveolar bone loss in vivo caused by periodontal disease. Collectively, the above findings may provide a valuable direction for the development of novel antiresorptive therapies that target RANKL.

Genome-wide gain-of-function screening identifies EZH2 mediating resistance to PI3Kα inhibitors in oesophageal squamous cell carcinoma.

Phosphoinositide-3 kinase alpha (PI3Kα) has been confirmed to be a potential therapeutic target for esophageal squamous cell carcinoma (ESCC), while the potency of PI3Kα inhibitors is often attenuated by concurrent oncogenic signalling pathways. We performed genome-wide gain-of-function screening with a CRISPR-SAM library and identified enhancer of zeste homolog 2 (EZH2) rendering ESCC cells resistant to the PI3Kα inhibitor CYH33. Enhanced expression of EZH2 frequently occurs in ESCC and is related to poor prognosis. Overexpression of full-length EZH2 but not methyltransferase-deficient EZH2 conferred resistance to CYH33, while downregulating EZH2 expression restored sensitivity. EZH2 expression was negatively related to the activity of CYH33 against the proliferation of ESCC cell lines and patient-derived cells. Transcriptomic analysis revealed that EZH2 abrogated CYH33-mediated cell cycle regulation. EZH2 epigenetically suppressed the transcription of CDKN1A, promoting RB phosphorylation and cell cycle progression. Concurrently targeting EZH2 significantly potentiated CYH33 to inhibit the growth of ESCC cells and patient-derived xenografts accompanied by enhanced cell cycle arrest. Taken together, our study demonstrated that an EZH2-p21-RB axis remodeled cell cycle regulation and rendered resistance to PI3Kα inhibitors in ESCC. Simultaneously targeting PI3Kα and EZH2 may provide an effective strategy for ESCC therapy with high expression of EZH2.

Design, synthesis and evaluation of the Brigatinib analogues as potent inhibitors against tertiary EGFR mutants (EGFRdel19/T790M/C797S and EGFRL858R/T790M/C797S).

Although epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have demonstrated encouraging clinical outcomes for patients with EGFR-mutated non-small cell lung cancer, a considerable number of patients will develop drug resistance and eventually undergo disease progression after taking EGFR-TKIs for a period of time. EGFRdel19/T790M/C797S and EGFRL858R/T790M/C797S are two most prevalent tertiary EGFR mutants identified in Osimertinib-resistant tumors and currently there is no therapy approved clinically targeting these mutants. In this study, we designed and synthesized a series of novel 4th generation EGFR inhibitors based on scaffold of Brigatinib. After extensive SAR studies, compound 23, the most promising candidate, exhibited strong biochemical potencies against EGFRdel19/T790M/C797S, EGFRL858R/T790M/C797S and other clinically relevant EGFR mutants while sparing wild type EGFR. In cellular assays, compound 23 potently inhibited proliferation of BaF3EGFR del19/T790M/C797S and PC-9EGFR del19/T790M/C797S. Moreover, compound 23 demonstrated good DMPK profile in mouse PK study.

Repressing MYC by targeting BET synergizes with selective inhibition of PI3Kα against B cell lymphoma.

Phosphatidylinositol 3-kinase (PI3K) δ-specific inhibitors have been approved for the therapy of certain types of B cell lymphoma (BCL). However, their clinical use is limited by the substantial toxicity and lack of efficacy in other types of BCL. Emerging evidence indicates that PI3Kα plays important roles in the progression of B cell lymphoma. In this study, we revealed that PI3Kα was important for the PI3K signaling and proliferation in BCL cells. A novel clinical PI3Kα-selective inhibitor CYH33 possessed superior activity against BCL compared to the marketed PI3Kα-selective inhibitor Alpelisib and PI3Kδ-selective inhibitor Idelalisib. Though CYH33 was able to inhibit PI3K/AKT signaling in tested BCL cells, differential activity against proliferation was observed. Transcriptome profiling revealed that CYH33 down-regulated "MYC-targets" gene set in sensitive but not resistant cells. CYH33 inhibited c-MYC transcription in sensitive cells, which was attributed to a decrease in acetylated H3 bound to the promoter and super-enhancer region of c-MYC. Accordingly, CYH33 treatment resulted in phosphorylation and proteasomal degradation of the histone acetyltransferase p300. An unbiased screening with drugs approved or in clinical trials for the therapy of BCL identified that the clinical BET (Bromodomain and Extra Terminal domain) inhibitor OTX015 significantly potentiated the activity of CYH33 against BCL in vitro and in vivo, which was associated with enhanced inhibition on c-MYC expression and induction of cell cycle arrest and apoptosis. Our findings provide the rationale of combined CYH33 with BET inhibitors for the therapy of B cell lymphoma.

Synthesis and Biological Evaluation of C-17-Amino-Substituted Pyrazole-Fused Betulinic Acid Derivatives as Novel Agents for Osteoarthritis Treatment.

A series of pyrazole-fused betulinic acid (BA) derivatives were designed and synthesized by replacing the carboxyl group at C-17 with aliphatic amine, amide, and urea groups. The suppressive effects of the compounds on osteoclast (OC) formation and inflammatory cytokine production were evaluated on murine macrophages, RAW264.7 cells, conditioned with receptor activator for nuclear factor-κB ligand (RANKL)/macrophage colony stimulating factor (M-CSF) or lipopolysaccharide (LPS), respectively. Results showed that, compared with betulinic acid, most of these compounds exhibited significant improvements in inhibitory potency. Compound 25 exhibited distinguished activities on inhibiting OC differentiation with an IC50 value of 1.86 µM. Meanwhile, compound 25, displaying the most promising suppression on IL-1ß secretion from RAW264.7 cells, was further found to possess therapeutic effects in the sodium monoiodoacetate (MIA)-induced osteoarthritis rat model. Dose-dependent benefits were observed in MIA-elicited rats with ameliorated joint pain as well as decreased cartilage damage and bone changes after compound 25 treatment.

Effect of flushing temperature on preparation ability of rotary nickel-titanium files.

PURPOSE: The effect of flushing at different temperatures on the preparation ability of rotary nickel-titanium files was investigated to provide guideline for clinical application. METHODS: Sixty ProTaper Universal F1 rotary nickel-titanium files were randomly divided into three groups treated by flushing at 6°C, 23°C, and 40°C. Root canal preparation was conducted by step-by-step method on standardized nickel-titanium instrument fracture models. During preparation, the thrust force was set as 10 N, and water was continuously flushed. The motor speed was 350 rpm (rounds per minute), and the torque was 3.0 N cm. When the set torque was reached, the motor automatically rotated in the reverse direction and was pulled out. RESULTS: Root canal preparation was performed using ProTaper Universal F1 rotary nickel-titanium files treated by flushing. The numbers of rotations before the device was fracture were 429.33 ± 214.68, 821.92 ± 410.43, and 1304.92 ± 297.81, respectively. When each root canal was completed, the numbers of instrument rotations were 272.15 ± 88.30, 188.85 ± 34.36, and 163.41 ± 16.18, respectively. Rank sum test and analysis of variance were performed by IBM SPSS Statistics v21.0 software, and both of them were p < 0.01, indicating that the number of cycles to failure (NCF) and the number of instrument rotations for each root tube were statistically different at the three temperatures. CONCLUSIONS: The self-made resin-simulated curved root canal can replace the real root canal to complete the root canal preparation experiment. The group of nickel-titanium files treated by flushing at 23°C can prepare more root canals and prolong the life of nickel-titanium files than at 6°C. When flushing was done at 40°C, the number of root canals prepared by nickel-titanium files was the highest, and it was not easy to damage the instrument, but lateral perforation occurred easily during root canal preparation.

Adaptive resistance to PI3Kα-selective inhibitor CYH33 is mediated by genomic and transcriptomic alterations in ESCC cells.

Phosphoinositide-3 kinase alpha-specific inhibitors (PI3Kαi) displayed promising potential for the treatment of esophageal squamous cell carcinoma (ESCC) with frequent activation in PI3K signaling. However, acquired resistance is likely to develop and limit the efficacy of PI3Kαi like other targeted therapies. To identify genomic adaptation to PI3Kαi, we applied whole-genome sequencing and detected gene mutation and amplification in four lines of ESCC cells established with adapted resistance to a novel PI3Kαi CYH33. Particularly, HRASG12S mutation was found in KYSE180C cells. Overexpression of HRASG12S in ESCC parental cells rendered resistance to CYH33. By contrast, down-regulation of HRASG12S restored the sensitivity of KYSE180C1 cells to CYH33, and combination of CYH33 and MEK162 displayed synergistic effect against KYSE180C1 cells and xenografts. Furthermore, elevated mTORC1, mitogen-activated protein kinase (MAPK), and c-Myc signaling pathways were found in resistant cells by RNA sequencing and combination of CYH33 and RAD001, MEK162, or OTX015 overcame the resistance to CYH33, which was accompanied with enhanced inhibition on S6, extracellular signal-regulated kinase 1 (ERK), or c-Myc, respectively. Overall, we characterized the adaptations to PI3Kαi in ESCC cells and identified combinatorial regimens that may circumvent resistance.

Effect of synchronous irrigation on cyclic fatigue of nickel-titanium instrument in the dynamic and static models.

OBJECTIVE: To evaluate the effect of synchronous water irrigation on the fatigue resistance of nickel-titanium instrument. METHODS: A standardized cyclic fatigue test models were established, and five types of nickel-titanium instruments (PTU F1, WO, WOG, RE, and M3) were applied. Each instrument was randomly divided into two groups (N = 12). There was synchronous water irrigation in the experimental group, and no water irrigation in the control group. Besides, ProTaper Universal F1 was randomly divided into 10 groups (N = 20). In the static group, nickel-titanium instruments were divided into one control group (no irrigation, N = 20) and six experimental group (irrigation, N = 20) based on different flow rate, angle and position; while in the dynamic group, instruments were divided into one control group (no irrigation, N = 20) and two experimental group (irrigation, N = 20) based on different flow rate. The rotation time (Time to Failure, TtF) of instruments was recorded and analyzed. RESULTS: According to the static experiments, the TtF of instruments in all experimental groups was significantly higher than that in the static control group. Besides, the dynamic tests of PTU F1 showed that the TtF in the experimental group was significantly higher than that in the dynamic control group. Compared with control group, the TtF in the experimental groups increased by at least about 30% and up to 160%. The static and dynamic tests of PTU F1 showed that the TtF of nickel-titanium instrument in all experimental groups was significantly higher than that in the control group. However, there was no significant difference between any two experimental groups. CONCLUSION: Regardless of dynamic or static model, TtF with irrigation was longer than that with non-irrigation, indicating that synchronous irrigation can increase the fatigue resistance of nickel-titanium instrument. However, different irrigation conditions may have the same effect on the fatigue resistance.

Identification of methyl (5-(6-((4-(methylsulfonyl)piperazin-1-yl)methyl)-4-morpholinopyrrolo[2,1-f][1,2,4]triazin-2-yl)-4-(trifluoromethyl)pyridin-2-yl)carbamate (CYH33) as an orally bioavailable, highly potent, PI3K alpha inhibitor for the treatment of advanced solid tumors.

In various human cancers, PI3Ks pathway is ubiquitously dysregulated and thus become a promising anti-cancer target. To discover new potent and selective PI3K inhibitors as potential anticancer drugs, new pyrrolo[2,1-f][1,2,4]triazines were designed, leading to the discovery of compound 37 (CYH33), a selective PI3Kα inhibitor (IC50 = 5.9 nM, ß/α, δ/α,γ/α = 101-, 13-, 38-fold). Western blot analysis confirmed that compound 37 could inhibit phosphorylation of AKT in human cancer cells to modulate the cellular PI3K/AKT/mTOR pathway. And further evaluation in vivo against SKOV-3 xenograft models demonstrated that a dose-dependent antitumor efficacy was achieved.

Identification of 2-substituted pyrrolo[1,2-b]pyridazine derivatives as new PARP-1 inhibitors.

A library of new 2-substituted pyrrolo[1,2-b]pyridazine derivatives were rapidly assembled and identified as PARP inhibitors. Structure-activity relationship for this class of inhibitor resulted in the discovery of most potent compounds 15a and 15b that exhibited about 29- and 5- fold selective activity against PARP-1 over PARP-2 respectively. The antiproliferative activity of the as-prepared compounds were demonstrated by further celluar assay in BRCA2-deficient V-C8 and BRCA1-deficient MDA-MB-436 cell lines, displaying that compound 15b could robustly reduce the corresponding cell proliferation and growth with CC50s of 340 and 106 nM respectively. The PK property of 15b was also investigated here.