Lipidomics characterization of the lipid metabolism profiles in a cystinuria rat model: Precalculus damage in the kidney of cystinuria.

Cystinuria is a genetic disorder of cystine transport, including defective protein b0,+AT (encoded by SLC7A9), and/or rBAT (encoded by SLC3A1). Patients present hyperexcretion of cystine in the urine, recurrent cystine lithiasis, and progressive decline in kidney function. Moreover, heterodimer transport is defective. To date, little omics data are accessible regarding this metabolic disease caused by membrane proteins. Since membrane function is closely related to changes in the lipidome, we decided to explore the changes in kidney tissue of a self-established cystinuria rat model by performing lipidomic analysis by LC-MS/MS. Our results demonstrated that Slc7a9 deficiency changed the lipid profile of the renal cortex and induced vital modifications in the lipidome, including major alterations in ChE, LPA, and PA. Among those alterations, this lipidomic study highlights the lipid changes that participate in inflammatory responses during cystinuria. As a result, lipid research, perhaps has great potential, for it may lead to the identification of novel therapeutic targets for the prevention and treatment of cystinuria.

Sulfoquinovosyl diacylglycerol synthase 1 impairs glycolipid accumulation and photosynthesis in phosphate-deprived rice.

Phosphate (Pi)-starved crops utilize phospholipids as a source for internal Pi supply by replacing non-phosphorus glycolipids. In rice, sulfoquinovosyl diacylglycerol synthase 1 (OsSQD1) functions as a key enzyme in the first step to catalyze sulfoquinovosyldiacylglycerol (SQDG) formation. Here we study differential expression of OsSQD1 in response to Pi, nitrogen, potassium, and iron-deficiencies in rice. Electrophoretic mobility shift assay suggested that OsSQD1 is regulated by OsPHR2 (Phosphate Starvation Response2), a MYB (v-myb avian myeloblastosis viral oncogene homolog) domain-containing transcription factor. The concentrations of different lipid species in ossqd1 knockout mutant demonstrated that OsSQD1 silencing increased the phospholipid content and altered fatty acid composition under Pi-deficiency. Moreover, OsSQD1 silencing reduces glycolipid accumulation under Pi-deficiency, and triggered the saturation of fatty acids in phospholipids and glycolipids treated with different Pi regimes. Relative amounts of transcripts related to phospholipid degradation and glycolipid synthesis were assessed to explore the mechanism by which OsSQD1 exerts an effect on lipid homeostasis under P-deficiency. Furthermore, OsSQD1 silencing inhibited photosynthesis, especially under Pi-deficient conditions, by down-regulating glycolipids in rice shoots. Taken together, our study reveals that OsSQD1 plays a key role in lipid homeostasis, especially glycolipid accumulation under Pi-deficiency, which results in the inhibition of photosynthesis.

Estimating Driving Fatigue at a Plateau Area with Frequent and Rapid Altitude Change.

Due to the influence of altitude change on a driver's heart rate, it is difficult to estimate driving fatigue using heart rate variability (HRV) at a road segment with frequent and rapid altitude change. Accordingly, a novel method of driving fatigue estimation for driving at plateau area with frequent altitude changes is proposed to provide active safety monitoring in real time. A naturalistic driving experiment at Qinghai-Tibet highway was conducted to collect drivers' electrocardiogram data and eye movement data. The results of the eye movement-based method were selected to enhance the HRV-based driving fatigue degree estimation method. A correction factor was proposed to correct the HRV-based method at the plateau area so that the estimation can be made via common portable devices. The correction factors for both upslope and downslope segments were estimated using the field experiment data. The results on the estimation of revised driving fatigue degree can describe the driver's fatigue status accurately for all the road segments at the plateau area with altitudes from 3540 to 4767 m. The results can provide theoretical references for the design of the devices of active safety prevention.

Phosphosulindac (OXT-328) selectively targets breast cancer stem cells in vitro and in human breast cancer xenografts.

Pharmacological targeting of breast cancer stem cells (CSCs) is highly promising for the treatment of breast cancer, as the small population of CSCs appears responsible for tumor initiation and progression and also for resistance to conventional treatment. Here we report that the novel phosphosulindac (OXT-328, PS) selectively and effectively eliminates breast CSCs both in vitro and in vivo. PS reduced cell proliferation and induced apoptosis in various breast CSCs. Breast CSCs are resistant to conventional cancer drugs but are sensitive to PS. Long-term treatment of mixtures of cultured breast CSCs and breast cancer cells with PS preferentially eliminated the CSCs. PS impaired the ability of CSCs to form mammospheres and markedly suppressed the expression of CSC-related genes. More importantly, PS prevented by half (p = .06) the formation of tumors initiated by CSCs in immunodeficient mice, and inhibited by 83% (p < .05) the growth of already formed breast cancer xenografts, reducing the proportion of CSCs in them. PS suppressed the Wnt/ß-catenin pathway by stimulating the degradation of ß-catenin and its relocalization to the cell membrane and also blocked the epithelial-mesenchymal transition and the generation of breast CSCs. These results indicate that PS has a strong inhibitory effect against breast cancer, acting, at least in part, by targeting CSCs through a signaling mechanism involving Wnt signaling.

Neoadjuvant transarterial chemoembolization (TACE) plus PD-1 inhibitor bridging to tumor resection in intermediate-stage hepatocellular carcinoma patients.

BACKGROUND: Programmed cell death protein 1 (PD-1) inhibitor is widely utilized in advanced-stage carcinomas including hepatocellular carcinoma (HCC), while its neoadjuvant application plus transarterial chemoembolization (TACE) in HCC remains unexplored. Thereby, the current study aimed to investigate the efficacy and safety of TACE plus PD-1 inhibitor as neoadjuvant therapy bridging to surgical resection in intermediate-stage HCC patients. METHODS: Twenty intermediate-stage HCC (China Liver Cancer (CNLC) stage II) patients treated with neoadjuvant TACE plus PD-1 inhibitor (camrelizumab or sintilimab) bridging to surgery were consecutively enrolled. RESULTS: The objective response rate (ORR) and disease control rate (DCR) to neoadjuvant therapy were 75.0% and 100.0%, respectively; meanwhile, alpha-fetoprotein (AFP) was decreased after the neoadjuvant therapy (P < 0.001). Moreover, 14 (70.0%) patients had successful downstaging (patients converted to CNLC stage I). Neither median disease-free survival (DFS) nor median overall survival (OS) was reached; additionally, the 1-year accumulating DFS rate was 86.6%; meanwhile, the 1-year and 2-year accumulating OS rates were 100.0% and 76.4%, separately. Moreover, patients with successful downstaging had a prolonged DFS (P = 0.014) compared to patients with failed downstaging; meanwhile, this trend was also observed in assessing accumulating OS (P = 0.067) (without statistical significance). Main adverse events included pain (50.0%), fever (25.0%), neutropenia (25.0%), nausea and vomiting (25.0%), fatigue (25.0%), peripheral neuropathy (20.0%), anemia (15.0%), thrombopenia (15.0%), diarrhea (15.0%), anorexia (15.0%), and rash (15.0%). CONCLUSION: Neoadjuvant TACE plus PD-1 inhibitor realizes a satisfying downstaging rate, acceptable survival profile, and tolerance in intermediate-stage HCC patients.

Assessment of particulate matter inhalation during the trip process with the considerations of exercise load.

A Particulate Matter (PM) inhalation model considering exercise load is established to evaluate the impact of PM on residents' travel health. The study chooses PM detectors to collect PM concentrations at the various transportation space, including walking, bicycle, bus, taxi, and subway. A multiple linear regression model revised by road greening is utilized to study the influence factors that have a potential impact on the PM concentration. The air inhalation model with the consideration of exercise load can be acquired by connecting the heart rate (HR) and individual characteristics. The PM2.5 and PM10 inhalation for a complete trip of traveler can be estimated using the proposed model based on air inhalation per time unit, travel time, and PM concentration. The analysis results using the experimental data in Xi'an indicate that PM concentrations in taxi carriage, bus carriage, and subway carriage are significantly different from those obtained from environmental monitoring stations. However, the difference is not significant in the locations of sidewalk, non-motorized lane, taxi station, bus station, subway concourse, and subway platform. PM concentration and humidity in background environment have a positive influence on the increase of PM concentration in transportation environment, while temperature and wind speed are negative. The mean values of air inhalation per time unit for male and female using each mode are in the range of 9.6-26.8 L/min and 9.8-27.8 L/min, respectively. Exposure time in non-motorized transportation has a large effect on PM inhalation of travelers, walking connections and waiting in motorized transportation are the main contributing states to PM inhalation of travelers. The results of the study can be used to predict travelers' PM inhalation in completed trips, and provide recommendations for travelers to choose a healthier mode.

Carboxylesterases 1 and 2 hydrolyze phospho-nonsteroidal anti-inflammatory drugs: relevance to their pharmacological activity.

Phospho-nonsteroidal anti-inflammatory drugs (phospho-NSAIDs) are novel NSAID derivatives with improved anticancer activity and reduced side effects in preclinical models. Here, we studied the metabolism of phospho-NSAIDs by carboxylesterases and assessed the impact of carboxylesterases on the anticancer activity of phospho-NSAIDs in vitro and in vivo. The expression of human liver carboxylesterase (CES1) and intestinal carboxylesterase (CES2) in human embryonic kidney 293 cells resulted in the rapid intracellular hydrolysis of phospho-NSAIDs. Kinetic analysis revealed that CES1 is more active in the hydrolysis of phospho-sulindac, phospho-ibuprofen, phospho-naproxen, phospho-indomethacin, and phospho-tyrosol-indomethacin that possessed a bulky acyl moiety, whereas the phospho-aspirins are preferentially hydrolyzed by CES2. Carboxylesterase expression leads to a significant attenuation of the in vitro cytotoxicity of phospho-NSAIDs, suggesting that the integrity of the drug is critical for anticancer activity. Benzil and bis-p-nitrophenyl phosphate (BNPP), two carboxylesterase inhibitors, abrogated the effect of carboxylesterases and resensitized carboxylesterase-expressing cells to the potent cytotoxic effects of phospho-NSAIDs. In mice, coadministration of phospho-sulindac and BNPP partially protected the former from esterase-mediated hydrolysis, and this combination more effectively inhibited the growth of AGS human gastric xenografts in nude mice (57%) compared with phospho-sulindac alone (28%) (p = 0.037). Our results show that carboxylesterase mediates that metabolic inactivation of phospho-NSAIDs, and the inhibition of carboxylesterases improves the efficacy of phospho-NSAIDs in vitro and in vivo.

Risk assessment of COVID-19 infection for subway commuters integrating dynamic changes in passenger numbers.

The COVID-19 global pandemic has had a significant impact on mass travel. We examined the risk of transmission of COVID-19 infection between subway commuters using the Susceptible Exposed Infected Recovered (SEIR) model. The model considered factors that may influence virus transmission, namely subway disinfection, ventilation capacity, average commuter spacing, single subway journey time, COVID-19 transmission capacity, and dynamic changes in passenger numbers. Based on these parameters, above a certain threshold (25 min), the risk of infection for susceptible people increased significantly as journey time increased. Average distance between commuters and levels of ventilation and disinfection were also important influencing factors. Meanwhile, the model also indicated that the risk of infection varied at different times of the day. Therefore, this paper recommends strengthening ventilation and disinfection in the carriages and limiting the time of single journeys, with an average distance of at least 1 m between passengers. In this light, subway commuters need to take proactive precautions to reduce their risk of COVID-19 infection. Also, the results show the importance of managing subway stations efficiently during epidemic and post-epidemic eras.

Health risk assessment of PM2.5 on walking trips.

PM2.5 has an impact on residents' physical health during travelling, especially walking completely exposed to the environment. In order to obtain the specific impact of PM2.5 on walking, 368 healthy volunteers were selected and they were grouped according to gender and age. In the experiment, the heart rate change rate (HR%) is taken as test variable. According to receiver operating characteristic (ROC) curve, the travel is divided into two states: safety and risk. Based on this, a binary logit model considering Body Mass Index (BMI) is established to determine the contribution of PM2.5 concentration and body characteristics to travel risk. The experiment was conducted on Chang'an Middle Road in Xi'an City. The analysis results show that the threshold of HR% for safety and risk ranges from 31.1 to 40.1%, and that of PM2.5 concentration ranges from 81 to 168 µg/m3. The probability of risk rises 5.8% and 11.4%, respectively, for every unit increase in PM2.5 concentration and HR%. Under same conditions, the probability of risk for male is 76.8% of that for female. The probability of risk for youth is 67.5% of that for middle-aged people, and the probability of risk for people with BMI in healthy range is 72.1% of that for non-healthy range. The research evaluates risk characteristics of walking in particular polluted weather, which can improve residents' health level and provide suggestions for travel decision while walking.

Development and validation of a deep learning model to screen hypokalemia from electrocardiogram in emergency patients.

BACKGROUND: A deep learning model (DLM) that enables non-invasive hypokalemia screening from an electrocardiogram (ECG) may improve the detection of this life-threatening condition. This study aimed to develop and evaluate the performance of a DLM for the detection of hypokalemia from the ECGs of emergency patients. METHODS: We used a total of 9908 ECG data from emergency patients who were admitted at the Second Affiliated Hospital of Nanchang University, Jiangxi, China, from September 2017 to October 2020. The DLM was trained using 12 ECG leads (lead I, II, III, aVR, aVL, aVF, and V1-6) to detect patients with serum potassium concentrations <3.5 mmol/L and was validated using retrospective data from the Jiangling branch of the Second Affiliated Hospital of Nanchang University. The blood draw was completed within 10 min before and after the ECG examination, and there was no new or ongoing infusion during this period. RESULTS: We used 6904 ECGs and 1726 ECGs as development and internal validation data sets, respectively. In addition, 1278 ECGs from the Jiangling branch of the Second Affiliated Hospital of Nanchang University were used as external validation data sets. Using 12 ECG leads (leads I, II, III, aVR, aVL, aVF, and V1-6), the area under the receiver operating characteristic curve (AUC) of the DLM was 0.80 (95% confidence interval [CI]: 0.77-0.82) for the internal validation data set. Using an optimal operating point yielded a sensitivity of 71.4% and a specificity of 77.1%. Using the same 12 ECG leads, the external validation data set resulted in an AUC for the DLM of 0.77 (95% CI: 0.75-0.79). Using an optimal operating point yielded a sensitivity of 70.0% and a specificity of 69.1%. CONCLUSIONS: In this study, using 12 ECG leads, a DLM detected hypokalemia in emergency patients with an AUC of 0.77 to 0.80. Artificial intelligence could be used to analyze an ECG to quickly screen for hypokalemia.

Phospho-sulindac (OXT-922) inhibits the growth of human colon cancer cell lines: a redox/polyamine-dependent effect.

Non-steroidal anti-inflammatory drugs such as sulindac are promising chemoprevention agents against colon cancer, but their weak potency and side effects limit their use for both chemoprevention and chemotherapy. Here, we evaluated the effect of a new sulindac derivative, phospho-sulindac or OXT-922, on the growth of human cancer cell lines and its mechanism of action. OXT-922 inhibited the growth of human cancer cell lines originating from colon, pancreas and breast ~11- to 30-fold more potently than sulindac. This effect was mediated by a strong cytokinetic effect. Compared with control, OXT-922 inhibited cell proliferation by up to 67%, induced apoptosis 4.1-fold over control and blocked the G(1) to S cell cycle phase transition. OXT-922 suppressed the levels of cell cycle regulating proteins, including cyclins D(1) and D(3) and Cyclin-dependent kinases (CDK) 4 and 6. The levels of intracellular reactive oxygen species (ROS), especially those of mitochondrial O2ⁱ⁻, were markedly elevated (5.5-fold) in response to OXT-922. ROS collapsed the mitochondrial membrane potential and triggered apoptosis, which was largely abrogated by antioxidants. OXT-922 suppressed nuclear factor-kappaB activation and downregulated thioredoxin-1 expression. It also suppressed the production of prostaglandin E(2) and decreased cyclooxygenase-1 expression. Similar to sulindac, OXT-922 enhanced spermidine/spermine N(1)-acetyltransferase activity, reduced the cellular polyamine content and synergized with difluoromethylornithine to inhibit cancer cell proliferation and induce apoptosis. Our results suggest that OXT-922 possesses promising anticancer properties and deserves further evaluation.

Synthesis and biological activity of novel shikonin analogues.

A series of shikonin analogues with side chain variants have been synthesized and evaluated for antitumor activity. These novel analogues show a broad spectrum of in vitro cytotoxicity against various cancer cell lines. Additionally, some analogues were also found to have the ability to decrease the expression level of HIF-1alpha in breast cancer cells MDA-MB-231 under hypoxia. The features of these analogues suggest their potential in cancer therapy.

alpha2,6-hyposialylation of c-Met abolishes cell motility of ST6Gal-I-knockdown HCT116 cells.

AIM: We aimed to investigate the potential modification of previously unrecognized surface glycoprotein(s) by alpha2,6-sialylation other than by integrins. METHODS: The expression of beta-galactoside alpha2,6-sialyltransferase (ST6Gal-I) in the colon cancer cell line HCT116 was reduced by siRNA. The adhesion and Boyden chamber assay were used to detect the variation in cell motility. alpha2,6-Sialylation proteins were detected with lectin affinity assay. The mRNA expression, protein expression and downstream signaling modulation with siRNA were detected using reverse transcription-polymerase chain reaction, flow cytometry analysis, and Western blot. RESULTS: In HCT116 cells, the knockdown of ST6Gal-I inhibited cell motility, but did not affect cell adhesion. This selectively altered cell migration was caused by the loss of alpha2,6-sialic acid structures on c-Met. Moreover, STAT3 was dephosphorylated at tyrosine 705 in ST6Gal-I-knockdown (ST6Gal-I-KD) HCT116 cells. CONCLUSION: c-Met is the substrate of ST6Gal-I. The hyposialylation of c-Met can abolish cell motility in ST6Gal-I-KD HCT116 cells.Acta Pharmacologica Sinica (2009) 30: 1039-1045; doi: 10.1038/aps.2009.84; published online 1 June 2009.

ADAM15 suppresses cell motility by driving integrin alpha5beta1 cell surface expression via Erk inactivation.

Human ADAM15 is unique among the A disintegrin and metalloprotease domain (ADAM) family because of the integrin binding motif Arg-Gly-Asp (RGD) within its disintegrin domain. Integrin alpha5beta1 has been reported to bind to ADAM15 in an RGD-dependent manner, but the biological significance of the interaction between ADAM15 and alpha5beta1 is unknown. To characterize the effects of ADAM15 on alpha5beta1-mediated cell adhesion and migration and elucidate the potential mechanism, CHO cells which express endogenous integrin alpha5beta1 were transfected with human ADAM15 cDNA. ADAM15 overexpression led to enhanced cell adhesion and decreased migration on fibronectin, which were suppressed by down-regulation of integrin alpha5. Overexpression of ADAM15 not only increased the cell surface expression of integrin alpha5 but also resulted in a more clustered staining of alpha5 on cell surface, while the beta1 subunit remained unchanged. Unexpectedly, results from immunoprecipitation and immunofluorescence indicated that ADAM15 and alpha5beta1 integrin did not interact directly in CHO cells. We found that ADAM15 expression decreased the phosphorylation of Erk1/2. Consistently, down-regulation of Erk1/2 phosphorylation by MEK inhibitor PD98059 or siRNA against Erk1/2 enhanced the expression of alpha5 on cell surface. By using a B16F10 pulmonary metastasis model, we revealed that overexpression of ADAM15 significantly reduced the number of metastatic nodules on the lung. Taken together, this study reveals for the first time that ADAM15 could drive alpha5 integrin expression on cell surface via down-regulation of phosphorylated Erk1/2. This presents a novel mechanism by which ADAM15 regulates cell-matrix adhesion and migration.

Growth arrest induced by C75, A fatty acid synthase inhibitor, was partially modulated by p38 MAPK but not by p53 in human hepatocellular carcinoma.

C75, a well-known fatty acid synthase (FAS) inhibitor, has been shown to possess potent anti-cancer activity in vitro and in vivo. In this study, we reveal that C75 is a cell cycle arrest inducer and explore the potential mechanisms for this effect in hepatocellular carcinoma (HCC) cell lines with abundant FAS expression: HepG2 and SMMC7721 cells with wt-p53, and Hep3B cells with null p53. The results showed FAS protein expression and basal activity levels were higher in HepG2 cells than in the other two HCC cell lines. Treatment with C75 inhibited FAS activity within 30 min of administration and induced G(2) phase arrest accompanied by p53 overexpression in HepG2 and SMMC7721 cells. By contrast, C75 triggered G(1) phase arrest in Hep3B cells, and RNA interference targeting p53 did not attenuate C75-induced G(2) arrest in HepG2 cells. Similarly, p53 overexpression via p53 plasmid transfection did not affect C75-induced G(1) phase arrest in Hep3B cells. However, we observed a clear correlation between p38 MAPK activation triggered by C75 and the induction of cell cycle arrest in all three HCC cells. Furthermore, treatment with the p38 MAPK inhibitor SB203580 reduced p38 MAPK activity and cell cycle arrest, and also partially restored cyclin A, cyclin B1, cyclin D1 and p21 protein levels. Collectively, it was p38 MAPK but not p53 involved in C75-mediated tumor cell growth arrest in HCC cells.

BC200 LncRNA a potential predictive marker of poor prognosis in esophageal squamous cell carcinoma patients.

OBJECTIVE: To explore the expression and prognosis significance of BC200 in esophageal squamous cell carcinoma (ESCC) patients who received radical resection. METHODS: We used quantitative real-time polymerase chain reaction to detect the expression level of BC200 in cancer tissue and paired adjacent normal tissue samples from 70 ESCC patients who received radical surgical resection and analyzed the correlation of the relative expression level of BC200 with clinical-pathological features and prognosis. RESULTS: We found that the relative expression of BC200 was significantly higher in ESCC tissues compared with adjacent normal tissue samples (P=0.023). But the expression of BC200 were not related to clinical-pathological features, such as age, TNM stages, and histological grade (P>0.05). Kaplan-Meier analysis showed that high expression levels of BC200 were correlated with poor prognosis in ESCC patients. Patients with a high level of BC200 had a shorter disease-free survival and overall survival than those with low BC200 expression (P=0.034 and P=0.031, respectively). On multivariate analysis, the hazard ratio (HR) of BC200 expression was 2.17 (95% confidence interval [CI]=1.12-4.19, P=0.022) for disease-free survival and 2.24 (95% CI=1.12-4.49, P=0.023) for overall survival. CONCLUSION: Our results indicate that high expression of BC200 reflects poor prognosis and could serve as a novel predictive marker for ESCC patients who received radical resection.

MC-12, an annexin A1-based peptide, is effective in the treatment of experimental colitis.

Annexin A1 (ANXA1) inhibits NF-κB, a key regulator of inflammation, the common pathophysiological mechanism of inflammatory bowel diseases (IBD). MC-12, an ANXA1-based tripeptide, suppresses NF-κB activation. Here, we determined the efficacy of MC-12 in the control of IBD. Mice with colitis induced by dextran sodium sulfate (DSS) or 2,4,6-trinitro benzene sulfonic acid (TNBS) were treated with various doses of MC-12 administered intraperitoneally, orally or intrarectally. We determined colon length and the histological score of colitis, and assayed: in colon tissue the levels of TNF-α, IFN-γ, IL-1ß, IL-6 and IL-10 by RT-PCR; prostaglandin E(2) (PGE(2)), cytoplasmic phospholipase A(2) (cPLA(2)) and myeloperoxidase by immunoassay; and COX-2 and NF- κB by immunohistochemistry; and in serum the levels of various cytokines by immunoassay. In both models MC-12: reversed dose-dependently colonic inflammation; inhibited by up to 47% myeloperoxidase activity; had a minimal effect on cytoplasmic phospholipase A(2); reduced significantly the induced levels of TNF-α, IFN-γ, IL-1ß, IL-6 and IL-10, returning them to baseline. DSS and TNBS markedly activated NF-κB in colonic epithelial cells and MC-12 decreased this effect by 85.8% and 72.5%, respectively. MC-12 had a similar effect in cultured NCM460 normal colon epithelial cells. Finally, MC-12 suppressed the induction of COX-2 expression, the level of PGE(2) in the colon and PGE(2) metabolite in serum. In conclusion, MC-12, representing a novel class of short peptide inhibitors of NF-κB, has a strong effect against colitis in two preclinical models recapitulating features of human IBD. Its mechanism of action is complex and includes pronounced inhibition of NF-κB. MC-12 merits further development as an agent for the control of IBD.

The role of histone deacetylase 7 (HDAC7) in cancer cell proliferation: regulation on c-Myc.

Histone deacetylases (HDACs) play fundamental roles in the epigenetic regulation of gene expression and contribute to the growth, differentiation, and apoptosis of cancer cells. Although HDACs are recognized to be closely related to cancer development and altered expression of certain HDACs is observed in tumor samples, the arcane characters of HDACs in tumorigenesis have not been fully illustrated. Herein, we report that HDAC7 is a crucial player in cancer cell proliferation. Knockdown of HDAC7 resulted in significant G(1)/S arrest in different cancer cell lines. Subsequent investigations indicated that HDAC7 silencing blocked cell cycle progression through suppressing c-Myc expression and increasing p21 and p27 protein levels. The ectopic expression of c-Myc in turn antagonized the cell cycle arrest and repressed the elevation of p21 and p27 in HDAC7 silencing setting. Of note, HDAC7 deficiency was further identified to induce cellular senescence program, which was also reversed by c-Myc re-expression. Further chromatin immunoprecipitation assays indicated that HDAC7 directly binds with c-Myc gene and HDAC7 silencing decreased c-Myc mRNA level via reducing histone H3/H4 acetylation and repressing the association of RNA polymerase II (RNAP II) with c-Myc gene. Taken together, our findings highlight for the first time an unrecognized link between HDAC7 and c-Myc and offer a novel mechanistic insight into the contribution of HDAC7 to tumor progression.

Dihydroartemisinin accelerates c-MYC oncoprotein degradation and induces apoptosis in c-MYC-overexpressing tumor cells.

Artemisinin and its derivatives (ARTs) are effective antimalarial drugs and also possess profound anticancer activity. However, the mechanism accounted for its distinctive activity in tumor cells remains unelucidated. We computed Pair wise Pearson correlation coefficients to identify genes that show significant correlation with ARTs activity in NCI-55 cell lines using data obtained from studies with HG-U133A Affymetrix chip. We found c-myc is one of the genes that showed the highest positive correlation coefficients among the probe sets analyzed (r=0.585, P<0.001). Dihydroartemisinin (DHA), the main active metabolite of ARTs, induced significant apoptosis in HL-60 and HCT116 cells that express high levels of c-MYC. Stable knockdown of c-myc abrogated DHA-induced apoptosis in HCT116 cells. Conversely, forced expression of c-myc in NIH3T3 cells sensitized these cells to DHA-induced apoptosis. Interestingly, DHA irreversibly down-regulated the protein level of c-MYC in DHA-sensitive HCT116 cells, which is consistent to persistent G1 phase arrest induced by DHA. Further studies demonstrated that DHA accelerated the degradation of c-MYC protein and this process was blocked by pretreatment with the proteasome inhibitor MG-132 or GSK 3beta inhibitor LiCl in HCT116 cells. Taken together, ARTs might be useful in the treatment of c-MYC-overexpressing tumors. We also suggest that c-MYC may potentially be a biomarker candidate for prediction of the antitumor efficacies of ARTs.

A series of alpha-heterocyclic carboxaldehyde thiosemicarbazones inhibit topoisomerase IIalpha catalytic activity.

A series of novel thiosemicarbazone derivatives bearing condensed heterocyclic carboxaldehyde moieties were designed and synthesized. Among them, TSC24 exhibited broad antiproliferative activity in a panel of human tumor cells and suppressed tumor growth in mice. The mechanism research revealed that TSC24 was not only an iron chelator but also a topoisomerase IIalpha catalytic inhibitor. Its inhibition on topoisomerase IIalpha was due to direct interaction with the ATPase domain of topoisomerase IIalpha which led to the block of ATP hydrolysis. Molecular docking predicted that TSC24 might bind at the ATP binding site, which was confirmed by the competitive inhibition assay. These results about the mechanisms involved in the anticancer activities of thiosemicarbazones will aid in the rational design of novel topoisomerase II-targeted drugs and will provide insights into the discovery and development of novel cancer therapeutics based on the dual activity to chelate iron and to inhibit the catalytic activity of topoisomerase IIalpha.