Design, synthesis, and biological evaluation of N-(pyridin-3-yl)pyrimidin-4-amine analogues as novel cyclin-dependent kinase 2 inhibitors for cancer therapy.

The discovery and development of CDK2 inhibitors has currently been validated as a hot topic in cancer therapy. Herein, a series of novel N-(pyridin-3-yl)pyrimidin-4-amine derivatives were designed and synthesized as potent CDK2 inhibitors. Among them, the most promising compound 7l presented a broad antiproliferative efficacy toward diverse cancer cells MV4-11, HT-29, MCF-7, and HeLa with IC50 values of 0.83, 2.12, 3.12, and 8.61 µM, respectively, which were comparable to that of Palbociclib and AZD5438. Interestingly, these compounds were less toxic on normal embryonic kidney cells HEK293 with high selectivity index. Further mechanistic studies indicated 7l caused cell cycle arrest and apoptosis on HeLa cells in a concentration-dependent manner. Moreover, 7l manifested potent and similar CDK2/cyclin A2 nhibitory activity to AZD5438 with an IC50 of 64.42 nM. These findings revealed that 7l could serve as ahighly promisingscaffoldfor CDK2 inhibitors as potential anticancer agents and functional probes.

Serum and urine metabolomics based on UPLC-QTOF/MS reveal the effect and potential mechanism of "schisandra-evodia" herb pair in the treatment of Alzheimer's disease.

The "schisandra-evodia" herb pair (S-E) is a herbal preparation to treat Alzheimer's disease (AD). This study aims to investigate the therapeutic efficacy and potential mechanism of S-E in AD rats, utilizing pharmacodynamic assessments and serum- and urine-based metabolomic analyses. Pharmacodynamic assessments included Morris water maze test, hematoxylin-eosin staining and immunohistochemistry experiments. The results of the study showed that the AD model was successful; the S-E significantly enhanced long-term memory and spatial learning in AD rats. Meanwhile, S-E notably ameliorated Aß25-35-induced cognitive impairment, improved hippocampal neuron morphology, decreased Aß deposition in the hippocampus and mitigated inflammatory damage. We then analyzed serum and urine samples using UPLC-MS/MS to identify potential biomarkers and metabolic pathways. Metabolomic analysis revealed alterations in 40 serum metabolites and 38 urine metabolites following S-E treatment, predominantly affecting pathways related to taurine and hypotaurine metabolism, linoleic acid metabolism, α-linolenic acid metabolism, glycerophospholipid metabolism and arachidonic acid metabolism. This study elucidates the biochemical mechanism underlying AD and the metabolic pathway influenced by S-E, laying the groundwork for future clinical applications.

Long-term air pollutants exposure and respiratory mortality: A large prospective cohort study.

Ambient air pollution is a major global health concern. Yet, no study has thoroughly assessed its link to respiratory mortality. Our research evaluated the combined and individual effects of air pollutants on respiratory mortality risks based on the UK Biobank. A total of 366,478 participants were studied. A Cox proportional hazards model was used to estimate the respiratory mortality risk from combined long-term exposure to five pollutants, summarized as a weighted air pollution score. During a median of 13.6 years of follow-up, 6113 deaths due to respiratory diseases were recorded. The hazard ratios (HRs) and 95% confidence intervals (95% CIs) of respiratory diseases were 2.64 (2.05-3.39), 1.62 (1.23-2.12), 2.06 (1.73-2.45), 1.20 (1.16-1.25), and 1.07 (1.05-1.08) per 10 µg/m3 increase in PM2.5, PM2.5-10, PM10, NO2, and NOx, respectively. The air pollution score showed a dose-response association with an elevated respiratory mortality risk. The highest versus lowest quartile air pollution score was linked to a 44% increase in respiratory mortality risk (HR 1.44, 95% CI: 1.33-1.57), with consistent findings in subgroup and sensitivity analyses. Long-term individual and joint air-pollutant exposure showed a dose-response association with an increased respiratory mortality risk, highlighting the importance of a comprehensive air-pollutant assessment to protect public health.

Serum 25-hydroxyvitamin D concentrations and colorectal cancer incidence in adults with type 2 diabetes.

BACKGROUND: To examine the association of serum 25-hydroxyvitamin D (25[OH]D) with colorectal cancer (CRC) risk in adults with type 2 diabetes (T2D). METHODS: Using UK Biobank data, this study included 18,453 adults with T2D. Serum 25(OH)D concentrations were determined by the chemiluminescent immunoassay method. A Cox proportional hazards model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for CRC outcomes. RESULTS: During a median follow-up of 8.8 years, there were 284 incident CRC cases. Compared with adults with serum 25(OH)D concentrations <25.0 nmol/L, the adjusted HRs (95% CIs) for lower to higher serum 25(OH)D concentrations (25.0 to <50.0, 50.0 to <75.0, and ≥75.0 nmol/L) were 0.61 (0.46-0.82), 0.50 (0.34-0.74), and 0.53 (0.30-0.94), respectively (Ptrend = 0.001). The risk of CRC decreased by 19.0% for per 1-SD increment in serum 25(OH)D concentrations. A nonlinear association of serum 25(OH)D concentrations with CRC risk was observed using a restricted cubic spline analysis (P nonlinearity = 0.002). CONCLUSIONS: Higher serum 25(OH)D concentrations were significantly and nonlinearly associated with a lower risk of CRC. These findings highlight the potential benefits of maintaining adequate vitamin D levels in CRC prevention among adults with T2D.

Association of Sugar-Sweetened, Artificially Sweetened, and Unsweetened Coffee Consumption With All-Cause and Cause-Specific Mortality : A Large Prospective Cohort Study.

BACKGROUND: Previous observational studies have suggested an association between coffee intake and reduced risk for death, but these studies did not distinguish between coffee consumed with sugar or artificial sweeteners and coffee consumed without. OBJECTIVE: To evaluate the associations of consumption of sugar-sweetened, artificially sweetened, and unsweetened coffee with all-cause and cause-specific mortality. DESIGN: Prospective cohort study. SETTING: Data were extracted from the UK Biobank. PARTICIPANTS: A total of 171 616 participants (mean age, 55.6 years [SD, 7.9]) without cardiovascular disease (CVD) or cancer at baseline were eligible. Baseline demographic, lifestyle, and dietary data from the UK Biobank were used, with follow-up beginning in 2009 and ending in 2018. MEASUREMENTS: Dietary consumption of sugar-sweetened, artificially sweetened, and unsweetened coffee was self-reported. All-cause, cancer-related, and CVD-related mortality were estimated. RESULTS: During a median follow-up of 7.0 years, 3177 deaths were recorded (including 1725 cancer deaths and 628 CVD deaths). Cox models with penalized splines showed U-shaped associations of unsweetened coffee, sugar-sweetened coffee, and artificially sweetened coffee with mortality. Compared with nonconsumers, consumers of various amounts of unsweetened coffee (>0 to 1.5, >1.5 to 2.5, >2.5 to 3.5, >3.5 to 4.5, and >4.5 drinks/d) had lower risks for all-cause mortality after adjustment for lifestyle, sociodemographic, and clinical factors, with respective hazard ratios of 0.79 (95% CI, 0.70 to 0.90), 0.84 (CI, 0.74 to 0.95), 0.71 (CI, 0.62 to 0.82), 0.71 (CI, 0.60 to 0.84), and 0.77 (CI, 0.65 to 0.91); the respective estimates for consumption of sugar-sweetened coffee were 0.91 (CI, 0.78 to 1.07), 0.69 (CI, 0.57 to 0.84), 0.72 (CI, 0.57 to 0.91), 0.79 (CI, 0.60 to 1.06), and 1.05 (CI, 0.82 to 1.36). The association between artificially sweetened coffee and mortality was less consistent. The association of coffee drinking with mortality from cancer and CVD was largely consistent with that with all-cause mortality. U-shaped associations were also observed for instant, ground, and decaffeinated coffee. LIMITATION: Exposure assessed at baseline might not capture changes in intake over time. CONCLUSION: Moderate consumption of unsweetened and sugar-sweetened coffee was associated with lower risk for death. PRIMARY FUNDING SOURCE: National Natural Science Foundation of China, Young Elite Scientist Sponsorship Program by CAST, and Project Supported by Guangdong Basic and Applied Basic Research Foundation.

SLC1A5 regulates cell proliferation and self-renewal through ß-catenin pathway mediated by redox signaling in arsenic-treated uroepithelial cells.

Arsenic exposure increases the risk of bladder cancer in humans, but its underlying mechanisms remain elusive. The alanine, serine, cysteine-preferring transporter 2 (ASCT2, SLC1A5) is frequently overexpressed in cancer cells. The aim of this study was to evaluate the effects of arsenic on SLC1A5, and to determine the role of SLC1A5 in the proliferation and self-renewal of uroepithelial cells. F344 rats were exposed to 87 mg/L NaAsO2 or 200 mg/L DMAV for 12 weeks. The SV-40 immortalized human uroepithelial (SV-HUC-1) cells were cultured in medium containing 0.5 µM NaAsO2 for 40 weeks. Arsenic increased the expression levels of SLC1A5 and ß-catenin both in vivo and in vitro. SLC1A5 promoted cell proliferation and self-renewal by activating ß-catenin, which in turn was dependent on maintaining GSH/ROS homeostasis. Our results suggest that SLC1A5 is a potential therapeutic target for arsenic-induced proliferation and self-renewal of uroepithelial cells.

Long-term air pollution exposure, habitual physical activity, and incident chronic kidney disease.

Both air pollution and physical inactivity contribute to the increased risk of incident chronic kidney disease (CKD). However, the detrimental effects of air pollution exposure could be augmented by an elevated intake of air pollutants during exercise. In the present study, we analyzed 367,978 participants who were CKD-free at baseline (2006-2010) based on the UK Biobank. Air pollutants included fine particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), and nitrogen oxides (NOX). Physical activity (PA) was obtained by the self-reported questionnaire. Using Cox proportional hazards models, hazard ratios (HRs) for incident CKD related to air pollution, PA, and incident CKD were evaluated. During a median of 12.4 years of follow-up, 14,191 incident CKD events were documented. High PM2.5, PM10, NO2, and NOX increased CKD risks by 11 %, 15 %, 14 %, and 12 %, respectively, while moderate and high PA reduced CKD risks by 18 % and 22 %, respectively. Participants with high PA and low air pollution exposure had 29 %, 31 %, 30 %, and 30 % risks of incident CKD than those with low PA and high air pollution exposure for the four air pollutants, with multivariable-adjusted HRs of 0.71 (95 % confidence intervals [CI]: 0.65-0.76) for PM2.5, 0.69 (95 % CI: 0.64-0.75) for PM10, 0.70 (95 % CI: 0.64-0.75) for NO2, and 0.70 (95 % CI: 0.64-0.75) for NOX. No clear interactions were observed between each air pollutant exposure and PA (all P for interaction > 0.05). The findings that reducing air pollution exposure and increasing PA were both independently correlated with a diminished risk of incident CKD suggest that PA could be targeted to prevent CKD generally regardless of air pollution levels. Further research is needed in areas polluted moderately and severely to examine our findings.

Synthesis and biological evaluation of novel 5-substituted/unsubstituted triazolothiadiazines as tubulin depolymerizing and vascular disrupting agents with promising antitumor activity.

A novel series of 5-substituted/unsubstituted [1,2,4]triazolo[3,4-b][1,3,4] thiadiazine compounds has been achieved successfully through chemoselective reduction of the C = N bond, based on our prior work. Initial biological evaluation illustrated that the most active derivative 7j exhibited significant cell growth inhibitory activity toward MCF-7, A549, HCT116, and A2780 with the IC50 values of 0.75, 0.94, 2.90, and 4.15 µM, respectively. Most importantly, all the representative analogs did not demonstrate obvious cytotoxic activity against the non-tumoural cell line HEK-293 (IC50 > 100 µM). The mechanism study revealed that 7j caused the G2 /M phase arrest, induced cell apoptosis in HeLa cells in a concentration-dependent manner, and also showed potent tubulin polymerization inhibitory effect. Meanwhile, 7j exerted significant antivascular activity in the wound-healing and tube formation assays. These observations indicate that 5-unsubstituted 6,7-dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine scaffold might be considered as a potential lead for antitubulin inhibitors to develop highly efficient anticancer agents with potent selectivity over normal human cells.

Association of smoking and polygenic risk with the incidence of lung cancer: a prospective cohort study.

BACKGROUND: Genetic variation increases the risk of lung cancer, but the extent to which smoking amplifies this effect remains unknown. Therefore, we aimed to investigate the risk of lung cancer in people with different genetic risks and smoking habits. METHODS: This prospective cohort study included 345,794 European ancestry participants from the UK Biobank and followed up for 7.2 [6.5-7.8] years. RESULTS: Overall, 26.2% of the participants were former smokers, and 9.8% were current smokers. During follow-up, 1687 (0.49%) participants developed lung cancer. High genetic risk and smoking were independently associated with an increased risk of incident lung cancer. Compared with never-smokers, HR per standard deviation of the PRS increase was 1.16 (95% CI, 1.11-1.22), and HR of heavy smokers (≥40 pack-years) was 17.89 (95% CI, 15.31-20.91). There were no significant interactions between the PRS and the smoking status or pack-years. Population-attributable fraction analysis showed that smoking cessation might prevent 76.4% of new lung cancers. CONCLUSIONS: Both high genetic risk and smoking were independently associated with higher lung cancer risk, but the increased risk of smoking was much more significant than heredity. The combination of traditional risk factors and additional PRS provides realistic application prospects for precise prevention.

Glucosamine use, smoking and risk of incident chronic obstructive pulmonary disease: a large prospective cohort study.

Chronic inflammation exerts pleiotropic effects in the aetiology and progression of chronic obstructive pulmonary disease (COPD). Glucosamine is widely used in many countries and may have anti-inflammatory properties. We aimed to prospectively evaluate the association of regular glucosamine use with incident COPD risk and explore whether such association could be modified by smoking in the UK Biobank cohort, which recruited more than half a million participants aged 40-69 years from across the UK between 2006 and 2010. Cox proportional hazards models with adjustment for potential confounding factors were used to calculate hazard ratios (HR) as well as 95 % CI for the risk of incident COPD. During a median follow-up of 8·96 years (interquartile range 8·29-9·53 years), 9016 new-onset events of COPD were documented. We found that the regular use of glucosamine was associated with a significantly lower risk of incident COPD with multivariable adjusted HR of 0·80 (95 % CI, 0·75, 0·85; P < 0·001). When subgroup analyses were performed by smoking status, the adjusted HR for the association of regular glucosamine use with incident COPD were 0·84 (0·73, 0·96), 0·84 (0·77, 0·92) and 0·71 (0·62, 0·80) among never smokers, former smokers and current smokers, respectively. No significant interaction was observed between glucosamine use and smoking status (Pfor interaction = 0·078). Incident COPD could be reduced by 14 % to 84 % through a combination of regular glucosamine use and smoking cessation.

Concise synthesis and preliminary biological evaluation of new triazolylthioacetone derivatives bearing pyridine, pyrazine, and 3,4,5-trimethoxybenzyl fragment.

Based on our previous work, a series of novel triazolylthioacetones incorporating pyridine, pyrazine, and 3,4,5-trimethoxybenzyl fragment were synthesized, and evaluated for antiproliferative activities and interactions with tubulin. Some analogues exhibited moderate to excellent potency, with the most promising compound IIc possessing IC50 values of 0.62, 1.46, and 3.65 µM against HT-29, HCT116, and HepG2 tumor cells, respectively, which were comparable with the positive control CA-4. Mechanistical studies revealed that IIc concentration-dependently caused cell cycle arrest at the G2/M phase in HCT116 tumor cells, and displayed a significant inhibition of tubulin polymerization with an IC50 value of 12.7 µM. Moreover, molecular docking analysis suggested that IIc could occupy the colchicine-binding site in a similar way with typical tubulinpolymerizationinhibitors. These results highlighted the 4-amino-triazolylthioacetone scaffold as potential tubulin polymerization inhibitors for development of highly efficient anticancer agents.

Efficient synthesis and evaluation of novel 6-arylamino-[1,2,4]triazolo[4,3-a]pyridine derivatives as antiproliferative agents.

Based on our previous work, a series of novel 6-arylamino-[1,2,4]triazolo[4,3-a]pyridine derivatives were synthesized, and evaluated for antiproliferative activities. SAR studies revealed that inserting an amino linkage between 6­aryl group and [1,2,4]triazolo[4,3-a]pyridine core led to amuch broaderantitumorspectrum, and the most promising compound 8 l exerted potent andbroad-spectrum antiproliferative activity toward HeLa, HCT116, MCF-7, and A549 cell lines, with IC50 values in the micromolar range of 5.98-12.58 µM, which were more active than the positive control 5-FU. The mechanism investigation illustrated that 8 l dose-dependently caused cell cycle arrest at the G2/M phase, and induced cell apoptosis in HeLa cells. Consequently, these findings suggest the 6-arylamino-[1,2,4]triazolo[4,3-a]pyridines afford significant potential for the discovery of a new highly efficient anticancer agents.

Association of physical activity and air pollution exposure with the risk of type 2 diabetes: a large population-based prospective cohort study.

BACKGROUND: The interplay between physical activity (PA) and air pollution in relation to type 2 diabetes (T2D) remains largely unknown. Based on a large population-based cohort study, this study aimed to examine whether the benefits of PA with respect to the risk of T2D are moderated by exposure to air pollution. METHODS: UK Biobank participants (n = 359,153) without diabetes at baseline were included. Information on PA was obtained using the International Physical Activity Questionnaire short form. Exposure to air pollution, including PM2.5, PMcoarse (PM2.5-10), PM10, and NO2, was estimated from land use regression models. Cox regression models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (95% CIs). RESULTS: During a median of 8.9 years of follow-up, 13,706 T2D events were recorded. Compared with a low PA level, the HRs for the risk of T2D among individuals with moderate and high PA were 0.82 (95% CI, 0.79-0.86) and 0.73 (95% CI, 0.70-0.77), respectively. Compared with low levels of air pollution, the HRs for risk of T2D for high levels of air pollution (PM2.5, PMcoarse, PM10, and NO2) were 1.19 (1.14-1.24), 1.06 (1.02-1.11), 1.13 (1.08-1.18), and 1.19 (1.14-1.24), respectively. There was no effect modification of the associations between PA and T2D by air pollution (all P-interactions > 0.05). The inverse associations between PA and T2D in each air pollution stratum were generally consistent (all P for trend < 0.05). CONCLUSION: A higher PA and lower air pollution level were independently associated with a lower risk of T2D. The beneficial effects of PA on T2D generally remained stable among participants exposed to different levels of air pollution. Further studies are needed to replicate our findings in moderately and severely polluted areas.

1,4-Dihydropyridinebutyrolactone-derived ring-opened ester and amide analogs targeting BET bromodomains.

Based on a previously reported 1,4-dihydropyridinebutyrolactone virtual screening hit, nine lactone ring-opened ester and seven amide analogs were prepared. The analogs were designed to provide interactions with residues at the entrance of the ZA loop of the testis-specific bromodomain (ZA) channel to enhance the affinity and selectivity for the bromodomain and extra-terminal (BET) subfamily of bromodomains. Compound testing by AlphaScreen showed that neither the affinity nor the selectivity of the ester and lactam analogs was improved for BRD4-1 and the first bromodomain of the testis-specific bromodomain (BRDT-1). The esters retained affinity comparable to the parent compound, whereas the affinity for the amide analogs was reduced 10-fold. A representative benzyl ester analog was found to retain high selectivity for BET bromodomains as shown by a BROMOscan. X-ray analysis of the allyl ester analog in complex with BRD4-1 and BRDT-1 revealed that the ester side chain is located next to the ZA loop and solvent exposed.

Effects of TIMP-2 Polymorphisms on Retinopathy of Prematurity Risk, Severity, Recurrence, and Treatment Response.

Tissue inhibitors of metalloproteinases (TIMPs) play a crucial role in endogenous angiogenesis besides the regulation of matrix metalloproteinase (MMP) activity. Associations between TIMP-2 gene polymorphisms and the risk of retinopathy of prematurity (ROP) were examined. Premature infants born between 2009 and 2018 were included. Five single-nucleotide polymorphisms (SNPs) of TIMP-2 were analyzed with real-time polymerase chain reaction (PCR). Multivariate logistic regression was applied to model associations between TIMP-2 polymorphisms and ROP susceptibility and severity. The GA+AA genotype in individuals with the TIMP-2 polymorphism of rs12600817 was associated with a higher risk of ROP (odds ratio [OR]: 1.518, 95% confidence interval [CI]: 1.028-2.242) compared with their wild-type genotypes. The AA genotype (OR: 1.962, 95% CI: 1.023-3.762) and the AA+GA genotype (OR: 1.686, 95% CI: 1.030-2.762) in individuals with the rs12600817 polymorphism had higher risks of severe, treatment-requiring ROP relative to their wild-type counterparts. In patients with treatment-requiring ROP, the AG+GG genotypes in the TIMP-2 polymorphism of rs2889529 were correlated with the treatment response (p = 0.035). The TIMP-2 polymorphism of rs12600817 help in predicting ROP risks in preterm infants, while the polymorphism of rs2889529 can serve as a genetic marker in evaluating the ROP treatment response.

Design, synthesis and antiproliferative activity of novel 2,4-diamino-5-methyleneaminopyrimidine derivatives as potential anticancer agents.

In order to discover new anticancer agents, 25 novel 2,4-diamino-5-methyleneaminopyrimidine derivatives were designed and synthesized based on our previous work via a ring-opening strategy. Among them, compared with 5-FU, compound 7i exhibited 4.9-, 2.9-, 2.1-, and 3.0-fold improvement in inhibiting HCT116, HT-29, MCF-7, and HeLa cells proliferation with IC50 values of 4.93, 5.57, 8.84, and 14.16 µM, respectively. Moreover, further mechanistic studies indicated that compound 7i could concentration-dependently induce cell cycle arrest and apoptosis in HCT116 cells. These findings revealed that 2,4-diamino-5-methyleneaminopyrimidine scaffold has potential for further investigation to explore novel anticancer agents.

Synthesis and antiproliferative evaluation of novel 8-cyclopentyl-7,8-dihydropteridin-6(5H)-one derivatives as potential anticancer agents.

Based on our previous work, a novel class of 8-cyclopentyl-7,8-dihydropteridin-6(5H)-one derivatives were synthesized and evaluated as antiproliferative agents. Structure-activity relationship analysis revealed that the greatest activities were achieved with a 4-(4-methylpiperazin-1-yl)aniline group at C-2 position of dihydropteridin-6(5H)-one core, and the most promising compound 6k demonstrated comparable antiproliferative activity with Palbociclib and more potent than our parent derivative 4 toward four cell lines including HCT-116, HeLa, HT-29, and MDA-MB-231 with IC50 values of 3.29, 6.75, 7.56, and 10.30 µM, respectively. Moreover, the mechanism studies revealed that compound 6k could induce cell cycle arrest at G2/M phase via a concentration-dependent manner. In general, these preliminary observations suggested that these compounds could serve as promising scaffolds for further modification to develop novel and highly potent cancer therapy agents.

Synthesis, biological evaluation, and structure-activity relationships of new tubulin polymerization inhibitors based on 5-amino-1,2,4-triazole scaffold.

Based on our previous research, thirty new 5-amino-1H-1,2,4-triazoles possessing 3,4,5-trimethoxyphenyl moiety were synthesized, and evaluated for antiproliferative activities. Among them, compounds IIa, IIIh, and IIIm demonstrated significant antiproliferative activities against a panel of tumor cell lines, and the promising compound IIIm dose-dependently caused G2/M phase arrest in HeLa cells. Furthermore, analogue IIa exhibited the most potent tubulinpolymerization inhibitory activity with an IC50 value of 9.4 µM, and molecular modeling studies revealed that IIa formed stable interactions in the colchicine-binding site of tubulin, suggesting that 5-amino-1H-1,2,4-triazole scaffold has potential for further investigation to develop novel tubulin polymerization inhibitors with anticancer activity.

Development of pteridin-7(8H)-one analogues as highly potent cyclin-dependent kinase 4/6 inhibitors: Synthesis, structure-activity relationship, and biological activity.

CDK4/6 have been validated as the cancer therapeutic targets. Here, we describe a series of pteridin-7(8H)-one analogues as potent CDK4/6 inhibitors. Among them, the most promising compound 7s demonstrated remarkable and broad-spectrum antiproliferative activities toward HCT116, HeLa, MDA-MB-231, and HT-29 cells with IC50 values of 0.65, 0.70, 0.39, and 2.53 µM, respectively, which were more potent than that of the anticancer drug Palbociclib. Interestingly, 7s also manifested the greatest inhibitory activities toward both CDK4/cyclin D3 and CDK6/cyclin D3 (IC50 = 34.0 and 65.1 nM, respectively), which was comparable with Palbociclib. Additionally, molecular simulation indicated that 7s bound efficiently at the ATPbindingsitesofCDK4 and CDK6. Further mechanistic studies revealed that compound 7s could concentration-dependently induce cell cycle arrest and apoptosis in HeLa cells. Takentogether, 7s represents a promising novel CDK4/6 inhibitor for the potential treatment of cancer.

Synthesis and biological evaluation of novel pyrazolo[3,4-b]pyridines as cis-restricted combretastatin A-4 analogues.

Twenty-six novel pyrazolo[3,4-b]pyridine-bridged analogues of combretastatin A-4 possessing 3,4,5-trimethoxylphenyl groups, were synthesized and evaluated for their antiproliferative and tubulin polymerization inhibitory activities. Preliminary biological evaluation demonstrated that some of the target compounds displayed significant antiproliferative effectagainst four different cell lines including MCF-7, MDA-MB-231, HeLa and Kyse150. The most active analogue 6n was found to induce HeLa cells arrest in the G2/M phase in a dose-dependent manner. Molecular modeling studies indicated that derivative 6n most likely occupies the colchicine site of tubulin. The initial results suggest that the 3,4,5-trimethoxyphenyl substituted pyrazolo[3,4-b]pyridine could serve as a promising scaffold for development of potent tubulin inhibitors as anticancer agents.