MicroRNA-Mediated Obstruction of Stem-loop Alternative Splicing (MIMOSAS): a global mechanism for the regulation of alternative splicing.

While RNA secondary structures are critical to regulate alternative splicing of long-range pre-mRNA, the factors that modulate RNA structure and interfere with the recognition of the splice sites are largely unknown. Previously, we identified a small, non-coding microRNA that sufficiently affects stable stem structure formation of Nmnat pre-mRNA to regulate the outcomes of alternative splicing. However, the fundamental question remains whether such microRNA-mediated interference with RNA secondary structures is a global molecular mechanism for regulating mRNA splicing. We designed and refined a bioinformatic pipeline to predict candidate microRNAs that potentially interfere with pre-mRNA stem-loop structures, and experimentally verified splicing predictions of three different long-range pre-mRNAs in the Drosophila model system. Specifically, we observed that microRNAs can either disrupt or stabilize stem-loop structures to influence splicing outcomes. Our study suggests that MicroRNA-Mediated Obstruction of Stem-loop Alternative Splicing (MIMOSAS) is a novel regulatory mechanism for the transcriptome-wide regulation of alternative splicing, increases the repertoire of microRNA function and further indicates cellular complexity of post-transcriptional regulation.

Discovery of effective combination from Renshen-Fuzi herbal pair against heart failure by spectrum-effect relationship analysis and zebrafish models.

ETHNOPHARMACOLOGICAL RELEVANCE: Traditional herbal pair Ginseng Radix et Rhizoma (roots and rhizomes of Panax ginseng C.A. Mey, Renshen in Chinese) and Aconiti Lateralis Radix Praeparata (lateral roots of Aconitum carmichaelii Debeaux, Fuzi in Chinese), composition of two traditional Chinese medicinal herbs, has been widely used in traditional Chinese medicine formula, in which Shenfu decoction has been used clinically in China for the treatment of heart failure at present. AIM OF THE STUDY: Although the ginsenosides and aconite alkaloids have been proven as the essential bioactive components in Renshen-Fuzi herbal pair, the exact composition of effective components to combat heart failure are still unclear. Therefore, spectrum-effect relationship analysis was performed to reveal its effective combination for anti-heart failure effect. MATERIALS AND METHODS: Firstly, the chemical constituents of Renshen-Fuzi herbal pair were identified using ultra high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS). The 39 major compounds in Renshen-Fuzi with five different compatibility ratios were simultaneously quantified using ultra high-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UHPLC-QQQ MS/MS). Subsequently, zebrafish models induced by verapamil hydrochloride were constructed and four heart failure-related indexes were selected for pharmacodynamic evaluation of Renshen-Fuzi. To analyze the spectrum-effect relationships, partial least squares regression (PLSR) models were established among the contents of 39 compounds in Renshen-Fuzi with each pharmacodynamic index. According to the contribution of each compound to the whole efficacy, 12 compounds were finally screened out as the effective combination. RESULTS: A total of 157 chemical compounds of Renshen-Fuzi herbal pair were identified, in which 39 components were simultaneously determined. The pharmacological effects indicated that Renshen-Fuzi with 1:2 ratio exhibited the best effect based on zebrafish model, which could improve cardiac output and blood flow velocity and inhibit pericardial enlargement and venous blood stasis significantly. A combination of 9 ginsenosides and 3 aconite alkaloids based on a component-efficacy modeling by PLSR was screened, and exerted approximately equivalent pharmacological effects compared with Renshen-Fuzi herbal pair. CONCLUSIONS: Our findings elucidated the effective combination of Renshen-Fuzi herbal pair that has been used in clinic for the treatment of heart failure, which could also promote the pharmacological research and quality control of their formula such as Shenfu decoction.

Difluoromethylornithine rebalances aberrant polyamine ratios in Snyder-Robinson syndrome: mechanism of action and therapeutic potential.

Snyder-Robinson Syndrome (SRS) is caused by mutations in the spermine synthase (SMS) gene, the enzyme product of which converts the polyamine spermidine into spermine. Affecting primarily males, common manifestations of SRS include intellectual disability, osteoporosis, hypotonic musculature, and seizures, along with other more variable symptoms. Currently, medical management focuses on treating these symptoms without addressing the underlying molecular cause of the disease. Reduced SMS catalytic activity in cells of SRS patients causes the accumulation of spermidine, while spermine levels are reduced. The resulting exaggeration in spermidine-to-spermine ratio is a biochemical hallmark of SRS that tends to correlate with symptom severity in the patient. Our studies aim to pharmacologically manipulate polyamine metabolism to correct this polyamine imbalance and investigate the potential of this approach as a therapeutic strategy for affected individuals. Here we report the use of difluoromethylornithine (DFMO; eflornithine), an FDA-approved inhibitor of polyamine biosynthesis, in re-establishing normal spermidine-to-spermine ratios in SRS patient cells. Through mechanistic studies, we demonstrate that, while reducing spermidine biosynthesis, DFMO also stimulates the conversion of existing spermidine into spermine in cell lines with hypomorphic variants of SMS. Further, DFMO treatment induces a compensatory uptake of exogenous polyamines, including spermine and spermine mimetics, cooperatively reducing spermidine and increasing spermine levels. In a Drosophila SRS model characterized by reduced lifespan, adding DFMO to the feed extended lifespan. As nearly all known SRS patient mutations are hypomorphic, these studies form a foundation for future translational studies with significant therapeutic potential.

Totally mechanical Collard versus circular stapled cervical esophagogastric anastomosis for minimally invasive esophagectomy.

BACKGROUND: Previous studies have proposed that the totally mechanical Collard (TMC) method may reduce anastomotic leakage and stricture. This study aimed to compare the TMC method and the circular stapled (CS) method for cervical anastomosis after minimally invasive esophagectomy (MIE) for esophageal cancer. METHODS: From May 2017 to September 2020, 308 patients (165 in the CS group and 143 in the TMC group) were included in this study. The primary endpoints were anastomotic leakage and anastomotic stricture within 12 months. Propensity score matching was used to control potential selection bias. RESULTS: Anastomotic leak, anastomotic stricture, and refractory stricture (≥ 3 dilations) occurred in 30 (9.7%), 28 (9.1%), and 18 (5.8%) patients, respectively. The rate of anastomotic leak was similar in the CS and TMC methods (9.7 vs. 9.8%; P = 0.978), but anastomotic stricture (3.5 vs. 13.9%; P = 0.001) and refractory stricture (2.8 vs. 9.1%, P = 0.022) occurred less frequently in the TMC method. Propensity score matching yielded 128 patient pairs and confirmed these results. Multivariable analyses found that CS method, anastomotic leakage, and diabetes were independent predictors for both anastomotic stricture and refractory stricture. Subgroup analysis revealed that for patients with anastomotic leakage, the postoperative hospital stay in the TMC group was significantly longer than that in the CS group. CONCLUSION: In cervical anastomosis after MIE, the TMC method is superior to the CS method regarding anastomotic stricture and refractory stricture formation. However, compared to the CS method, the TMC method cannot lower the probability of anastomotic leakage, and anastomotic leakage with the TMC method requires a longer healing time.

Extensive open lobectomy experience is not a prerequisite for learning uniportal video-assisted thoracic surgery lobectomy.

BACKGROUND AND OBJECTIVES: Uniportal video-assisted thoracoscopic surgery (U-VATS) lobectomy has been increasingly adopted to manage early stage lung cancer. However, little information is available on whether this technique can be taught to surgeons inexperienced in open lobectomy. This study aimed to investigate the learning curve for U-VATS lobectomy performed by a single surgeon with limited open lobectomy experience. METHODS: From July 2018 to September 2020, 103 patients received U-VATS lobectomy for lung cancer by a single surgeon. The learning curve was assessed using three statistical methods: the moving average analysis, cumulative sum (CUSUM) analysis, and risk-adjusted CUSUM (RA-CUSUM) analysis. RESULTS: The moving average analysis showed a continuous decrease in operative time throughout the study period. The CUSUM analysis demonstrated three well-differentiated learning phases: Phase 1 (the initial 34 cases) representing the initial learning, Phase 2 (the middle 33 cases) representing the improvement of competence, and Phase 3 (the final 36 cases) representing technical proficiency. RA-CUSUM analysis revealed that the maximized cumulative surgical failure, defined as the maximum cumulative difference between the observed and predicted surgical failures, was found in the 61st case. CONCLUSIONS: U-VATS lobectomy is feasible for surgeons with limited open lobectomy experience. Multidimensional statistical analyses suggested that 61-67 cases were required to gain technical proficiency and ensure acceptable surgical outcomes.

An Empirical Study on the Improvement of College Students' Employability Based on University Factors.

With the popularization of higher education and the promotion of college enrollment expansion, the number of college graduates increases sharply. At the same time, the continuous transformation and upgrading of the industrial structure put forward higher requirements on the employability of college students, which leads to the imbalance between supply and demand in the labor market. The key to dealing with employment difficulties lie in the improvement of college students' employability. Therefore, we make a regression analysis of 263 valid samples from universities in Anhui Province and extract the factors that influence the improvement of college students' employability in the process of talent cultivation in university. The result shows that there is a positive correlation between course setting, course teaching, club activities, and college students' employability, among which the course teaching and club activities are the most critical factors which may influence college students' employability. In addition, from the viewpoint of individual college students, the overall grades of college students and the time of participating in the internship are also closely related to their employability, i.e., college students with good overall grades and long internship time should also have stronger employability.

Computed tomography-guided cyanoacrylate injection for localization of multiple ipsilateral lung nodules.

OBJECTIVES: To retrospectively assess the clinical effectiveness of CT-guided cyanoacrylate localization for multiple ipsilateral small pulmonary nodules (SPNs) and to determine the independent predictors for pneumothorax. METHODS: In total, 81 patients with 169 lesions undergoing CT-guided cyanoacrylate localization for multiple ipsilateral SPNs between September 2016 and July 2020 were enrolled (group M). Another 284 patients who received single SPN localization during the same period served as the control group (group S). Propensity score analysis was performed to minimize selection bias. Possible independent predictors for pneumothorax were evaluated using multivariate logistic regression analysis. RESULTS: Multiple ipsilateral SPN localization was successfully performed in all 81 patients. The incidences of successful targeting during localization and surgery were 100% and 98.8%, respectively. Seventy-seven patients (95.1%) underwent the procedure on the day before the surgery. Propensity matching created 81 pairs of patients. There were no significant differences in the incidence of successful targeting during localization and surgery, localization-related pain score, and additional morphine use between the two groups. However, group M was associated with a significant longer localization procedural time (p < 0.001) and a higher incidence of pneumothorax (p < 0.001). In multivariate analysis, position change was significantly associated with a sevenfold increase in the risk for pneumothorax (p = 0.001). CONCLUSIONS: CT-guided cyanoacrylate injection for multiple ipsilateral SPN localization was safe and reliable, and allowed a flexible surgical schedule, despite a lengthy procedure and an increased incidence of pneumothorax. Avoiding position change may help to reduce the occurrence of pneumothorax. KEY POINTS: • Compared to single SPN localization, multiple ipsilateral SPN localization using cyanoacrylate injection achieved comparable safety, reliability, and comfort. • CT-guided cyanoacrylate localization for multiple ipsilateral SPNs allowed a flexible surgical schedule. • Position change was the only independent risk factor for pneumothorax during the multiple ipsilateral SPN localization.

Losartan prevents bladder fibrosis and protects renal function in rat with neurogenic paralysis bladder.

AIMS: To investigate the effect of losartan on preventing bladder fibrosis and protecting renal function in rats with neurogenic paralysis bladder (NPB). MATERIALS AND METHODS: Rats were assigned to the transecting spinal nerves group (TSNG), transecting spinal nerves + losartan group (LSTG), and control group (CG). On Day 32 postsurgery, bladder capacity (BC), bladder compliance (ΔC), bladder leakage pressure (Pves.leak ) of TSNG and LSTG while BC, ΔC, and bladder threshold pressure (Pves.thre ) of CG were measured by cystometry in each cohort. Renal function and the expression quantity of Angiotensin Ⅱ (Ang II) in blood were detected, in addition Ang II, Ang II Type 1 receptor (AT1), transformation growth factor ß1 (TGFß1), Collagen Ⅲ, and collagen fibrin in the bladder tissue were detected too. RESULTS: ΔC in TSNG and LSTG decreased significantly compared to the CG. Pves.leak in TSNG and LSTG were significantly higher than Pves.thre in CG. Renal function of both TSNG and LSTG decreased significantly compared with the CG, but renal function in LSTG was better than in TSNG. Ang Ⅱ in blood and bladder tissue in TSNG and LSTG increased significantly compared with CG. AT1 was expressed in the bladder tissue of all rats. The TGFß1, Collagen Ⅲ, and collagen fibrin expression level increased significantly in TSNG compared with LSTG and CG, while these levels were not significantly different between CG and LSTG. CONCLUSION: Losartan might prevent NPB fibrosis by stopping the upregulated signaling of Ang II/AT1/TGFß1 and consequently may reduce kidney damage from occurring.

Thoracoscopic Pulmonary Segmentectomy With Collateral Ventilation Method.

BACKGROUND: Despite its popularity in recent years, segmentectomy still faces a challenge: the accurate delineation of the intersegmental plane, especially in complex segmentectomy. In this study, we describe a method using collateral ventilation to create an inflation-deflation line for video-assisted thoracoscopic surgery (VATS) segmentectomy and evaluated its efficacy in complex segmentectomy by comparing it with simple segmentectomy. METHODS: Enrolled in the study were 264 patients who underwent VATS segmentectomy from January 2017 to September 2018. We classified the clarity of the inflation-deflation line into 4 grades, and the procedures of grade 3 or 4 were considered successful. Meanwhile, we performed a propensity score matching analysis to compare complex and simple segmentectomy. RESULTS: Complete resection with free margins was achieved in all patients. In inflation-deflation line clarity evaluation, 245 patients were classified as grade 4 (92.8%), 10 as grade 3 (3.8%), 8 as grade 2 (3.0%), and 1 as grade 1 (0.4%). Procedural success (grade 3 or 4) was achieved in 255 patients (96.6%). Prolonged air leak (>5 days) was observed in 11 patients (4.2%). Propensity matching generated 83 pairs of well-matched patients. The proportion of procedural success and the incidence of prolonged air leak (>5 days) were similar in both groups. However, compared with simple segmentectomy, complex segmentectomy was associated with a longer median operative time (159 versus 135 minutes; P < .001). CONCLUSIONS: Collateral ventilation method is simple, safe, and effective in VATS segmentectomy to identify the intersegmental plane, and also well-adapted for complex segmentectomy.

Antinociceptive effects of rotigotine-loaded microspheres and its synergistic interactions with analgesics in inflammatory pain in rats.

Rotigotine-loaded microspheres (RoMS) are sustained-release formulations with prolonged anti-Parkinson's effects. Given that pain is a non-motor symptom of Parkinson's disease, this study investigated the antinociceptive effects of RoMS and their synergistic effects with analgesics on inflammatory pain. A model of inflammatory pain was prepared by intraplantarly injecting male Sprague-Dawley rats with carrageenan. The antinociceptive effects of RoMS, acetaminophen, and tramadol, both alone and in combination, were evaluated using the hind paw withdrawal latency in the hot plate test and Randall-Selitto test. The rotigotine concentrations in serum and tissues were assayed using ultra-performance liquid chromatography-tandem mass spectrometry. Isobolographic analysis was performed to evaluate the nature of the interactions of RoMS with acetaminophen or tramadol. The results showed that hind paw withdrawal latency to thermal and mechanical stimuli was significantly increased on day 3 and 7 after administered RoMS. Rotigotine could be detected in serum and tissues 3 and 7 days after an intramuscular injection of RoMS. However, the rotigotine concentration fell the detection limit of the assay on day 14 after administration. RoMS produced synergistic antinociceptive effects in the inflammatory pain model when RoMS is combined with acetaminophen or tramadol. These findings suggest that RoMS can relieve inflammatory pain in rats. Furthermore, the combination of RoMS with acetaminophen or tramadol produces synergistic antinociception, which may be clinically worthy because combination therapies may reduce the drug doses required for antinociception.

Nicotinamide mononucleotide adenylyltransferase uses its NAD+ substrate-binding site to chaperone phosphorylated Tau.

Tau hyper-phosphorylation and deposition into neurofibrillary tangles have been found in brains of patients with Alzheimer's disease (AD) and other tauopathies. Molecular chaperones are involved in regulating the pathological aggregation of phosphorylated Tau (pTau) and modulating disease progression. Here, we report that nicotinamide mononucleotide adenylyltransferase (NMNAT), a well-known NAD+ synthase, serves as a chaperone of pTau to prevent its amyloid aggregation in vitro as well as mitigate its pathology in a fly tauopathy model. By combining NMR spectroscopy, crystallography, single-molecule and computational approaches, we revealed that NMNAT adopts its enzymatic pocket to specifically bind the phosphorylated sites of pTau, which can be competitively disrupted by the enzymatic substrates of NMNAT. Moreover, we found that NMNAT serves as a co-chaperone of Hsp90 for the specific recognition of pTau over Tau. Our work uncovers a dedicated chaperone of pTau and suggests NMNAT as a key node between NAD+ metabolism and Tau homeostasis in aging and neurodegeneration.

Changes in bladder function with time following cystostomy in rats.

AIMS: To investigate bladder function patterns following cystostomy and determine the best time window for cystometric evaluation of bladder function in conscious rats. MATERIALS AND METHODS: Cystostomy was performed in rats of the first seven groups; thereafter, cystometry was performed in the designed time interval. Noncystostomy rats of group 8 voided freely as control. Basal bladder pressure (Pves.basal ), maximum bladder pressure (Pves.max ), bladder threshold pressure (Pves.thre ), voiding interval (VI), bladder contraction duration (CD), bladder compliance (ΔC), voided volume (VV), postvoiding residual urine (PVR), and bladder capacity (BC) were recorded and compared with cystostomy groups, with VV, PVR, BC compared with the control values. Bladders were collected after the urodynamic study for weighing, hematoxylin-eosin, and Masson staining to investigate pathological changes. RESULTS: Pves.basal , Pves.max , and Pves.thre trended downward, while BC, VI, VV, and ΔC trended upward on days 1 to 5 postcystostomy. BC and VV significantly decreased on days 1 to 3 postcystostomy compared with control values; on days 5 to 15 postcystostomy, Pves.basal , Pves.max , Pves.thre , VI, VV, BC, and PVR were stable, and BC, VV, and PVR showed no significant differences from the control values. However, on day 21 postcystostomy, BC increased significantly compared with the controls. Bladder weight increased in the cystostomy groups compared with the controls. Pathological analysis showed severe acute bladder inflammation on days 1 to 3, mild inflammation on days 5 to 15, and increased collagen deposition in bladder tissue on day 21 postcystostomy. CONCLUSION: Cystometric evaluation of bladder function in conscious rats is best performed on days 5 to 15 postcystostomy.

Extraction of essential oil from Citrus reticulate Blanco peel and its antibacterial activity against Cutibacterium acnes (formerly Propionibacterium acnes).

Citrus is one of the largest output fruits in the word. In China, the major orange variety is the Citrus reticulate Blanco (Ponkan). The peels are discarded as waste material, its comprehensive utilization is urgently needed. In this work, hydrodistillation method was developed to extract citrus essential oil (EO) from Blanco peel. With the optimal extraction conditions, the EO yield was more than 3%. By GC-MS analysis, 53 compounds were identified from the citrus EO. Terpenes compounds accounted for 71.2%, especially d-limonene (major composition) accounted for 58.9%. The obtained citrus EO showed remarkable antibacterial activity against Cutibacterium acnes (C. acnes, Formerly P. acnes) and common microorganisms such as S. aureus, B. subtilis, and E. coli. Even compared with the common antibiotics (such as erythromycin, clindamycin, and tetracycline) for acne therapy, its antibacterial activity against C. acnes is more excellent. This work provides a potential therapy material for the treatment of acne.

Comparison of cyanoacrylate and hookwire for localizing small pulmonary nodules: A propensity-matched cohort study.

BACKGROUND: Localizing small pulmonary nodules (SPNs) is a challenge during thoracoscopic resection, but preoperative computed tomography (CT)-guided localization using either cyanoacrylate or hookwire can be helpful. This study compared the safety, efficiency, and operability of the two techniques. METHODS: From September 2013 to November 2018, 269 patients (269 SPNs) who underwent preoperative CT-guided SPN localization were enrolled. A propensity-matched analysis, incorporating 13 variables, was performed to control potential selection bias. RESULTS: All the patients were divided into two groups: CT-guided cyanoacrylate localization group (Group C, n = 149) and CT-guided hookwire localization group (Group H, n = 120). Eighty-six patients were propensity-matched in each group. All SPNs were successfully removed thoracoscopically, and no conversion was required. Localization-related complications in the two groups were similar, including intrapulmonary focal hemorrhage (p = 0.823), pneumothorax (p = 1.000), or hemoptysis (p = 0.121). For pain assessment and management, the cyanoacrylate localization saw a lower pain score (p < 0.001) and less morphine use (p < 0.001). In Group H, the localization took a significantly longer time (p < 0.001). Covering only the patients in Group C, the sub-analysis found that cyanoacrylate localization on the day before surgery did not compromise the accuracy of intraoperative targeting or increase the incidence of complications, compared with the localization on the day of surgery (all p > 0.05). CONCLUSION: Compared to hookwire localization, CT-guided cyanoacrylate localization decreased pain and morphine use and allowed flexible surgical schedules, suggestive of its preferability for the resection of SPNs.

Effects of rotigotine and rotigotine extended-release microsphere therapy on myocardial ischemic injury in mice.

Rotigotine is a dopamine receptor agonist that can improve motor function in Parkinson's disease (PD) patients. Rotigotine extended-release microsphere (RoMS) is an extended-release intramuscular formulation that exhibits a sustained release of rotigotine over a 14-day period. The clinical trials of RoMS has been carried out in USA and China. The purpose of this study is to observe the effects of RoMS therapy on myocardial ischemic injury in mice, to know whether RoMS alleviate or deteriorate the myocardial ischemic injury while PD patient has onset of myocardial ischemia concurrent after administered with RoMS. A mouse model of myocardial ischemia was established using isoproterenol, and mice were pretreated with rotigotine or RoMS before inducing myocardial ischemic injury. The effects of rotigotine or RoMS therapy on the degree of myocardial ischemic injury were studied by evaluating troponin I level, creatine kinase-MB (CK-MB) activity, and histopathological changes in cardiomyocytes. The dopamine receptor blocker chlorpromazine was used to further investigate the effects of rotigotine or RoMS on myocardial ischemic injury. Furthermore, serum rotigotine concentrations were also assayed. When myocardial ischemia occurred during rotigotine or RoMS administration, troponin I level and CK-MB activity were decreased, and ischemia-induced histopathological changes in cardiomyocytes were alleviated. The effects of rotigotine were maintained only 12 h and after that no protective effect was observed. RoMS releases continuously into the circulation after intramuscular injection. The cardioprotective effects of RoMS were maintained 14 days after a single RoMS administration. When combined with chlorpromazine, the protective effects of rotigotine on myocardial ischemic injury were eliminated, and the protective effects of RoMS were also partially abolished. In the animal model of myocardial ischemia, pretreatment with rotigotine or RoMS does not deteriorate, but can alleviate cardiomyocyte injury. Furthermore, RoMS pretreatment show long-term and continuous protective effects on cardiomyocyte injury. RoMS therapy in PD patients at high risk for cardiovascular diseases may attenuate the degree of cardiomyocyte injury caused by ischemia.

Subcellular compartmentalization of NAD+ and its role in cancer: A sereNADe of metabolic melodies.

Nicotinamide adenine dinucleotide (NAD+) is an essential biomolecule involved in many critical processes. Its role as both a driver of energy production and a signaling molecule underscores its importance in health and disease. NAD+ signaling impacts multiple processes that are dysregulated in cancer, including DNA repair, cell proliferation, differentiation, redox regulation, and oxidative stress. Distribution of NAD+ is highly compartmentalized, with each subcellular NAD+ pool differentially regulated and preferentially involved in distinct NAD+-dependent signaling or metabolic events. Emerging evidence suggests that targeting NAD+ metabolism is likely to repress many specific mechanisms underlying tumor development and progression, including proliferation, survival, metabolic adaptations, invasive capabilities, heterotypic interactions with the tumor microenvironment, and stress response including notably DNA maintenance and repair. Here we provide a comprehensive overview of how compartmentalized NAD+ metabolism in mitochondria, nucleus, cytosol, and extracellular space impacts cancer formation and progression, along with a discussion of the therapeutic potential of NAD+-targeting drugs in cancer.

Discovery, synthesis of novel fusidic acid derivatives possessed amino-terminal groups at the 3-hydroxyl position with anticancer activity.

A series of novel fusidic acid (FA) derivatives were synthesized and screened for their in vitro cytotoxicity against the Hela, U87, KBV and MKN45 cancer cell lines. Selected FA derivatives with anti-tumor activity were firstly identified including compound 4, which exhibited good anti-proliferative activity with IC50 values in the range of 1.26-3.57 µM. Further research revealed that compound 4 induced Hela cells to undergo apoptosis by increasing the ratio of the cells in the Sub-G0/G1 phase via decreasing the neo-synthesized proteins in a dose-dependent manner from 1 to 10 µM. Compound 4 also showed good in vivo anti-tumor activity against the xenograft tumor of Hela cells and had no apparent toxicity. This study highlights the advantage of introducing the medium-length amino-terminal groups at the 3-OH position of FA to enhance its anti-tumor activity and suggests that compound 4 provides a starting point for designing more potent derivatives in the future.

Synthesis and biological evaluation of novel H6 analogues as drug resistance reversal agents.

Hederagenin is a naturally occurring pentacyclic triterpenoids compound with multiple pharmacological activities. We recently showed that H6, a synthetic derivative of hederagenin, could enhance the anticancer activity of paclitaxel in drug-resistant cells in vitro and in vivo, but showed poor solubility. With the aim of improving the drug resistant reversal activity of H6, here we designed and synthesized a series of novel H6 analogues. Our results showed that compound 10 at the concentration of 5 µM significantly enhanced the cytotoxicity of paclitaxel to drug-resistant KBV cells and sensitized cells to paclitaxel in arresting cells in G2/M phase and inducing apoptosis. We found that compound 10 might block the drug efflux of P-gp via stimulating P-gp ATPase activity. Importantly, compound 10 enhanced the efficacy of paclitaxel against KBV cancer cell-derived xenograft tumors. Finally, we summarized a preliminary structure-activity relationship of hederagenin by the drug resistant reversal activity of H6 analogues in vitro and compound 10 and H6in vivo. This study highlights the importance of nitrogen-containing derivatives of hederagenin C-28 in the development of novel drug resistance reversal agents.

Regioselective Arene and Heteroarene Functionalization: N-Alkenoxypyridinium Salts as Electrophilic Alkylating Agents for the Synthesis of α-Aryl/α-Heteroaryl Ketones.

A direct regioselective functionalization of arenes and heteroarenes using N-alkenoxypyridinium salts as electrophilic alkylating agents for the synthesis of α-aryl/heteroaryl ketones has been developed. The method generates alkylating agents from alkynes and N-pyridine oxide followed by site-selective electrophilic substitution with a broad range of arenes and heteroarenes including benzene derivates, phenols, ethers, indoles, pyrroles, furans, and thiophenes in one pot. Kinetic isotope effect measurements and DFT studies reveal that this reaction likely proceeds through a carbon-cation intermediate.

H6, a novel hederagenin derivative, reverses multidrug resistance in vitro and in vivo.

Multidrug resistance (MDR) is a serious obstacle encountered in cancer treatment, in which the overexpression of P-glycoprotein (P-gp) plays an important role. Here, a novel α-hederagenin derivative, designated H6, was designed, synthesized and evaluated for its ability to reverse MDR. Our results showed that H6 could sensitize KBV and MCF7/T cells to paclitaxel and vincristine. Meanwhile, H6 could increase both rhodamine 123 and paclitaxel accumulation in MDR cells without affecting the expression of P-gp. Interestingly, siRNA knockdown of MDR1 further sensitized the cytotoxic activity of paclitaxel when co-administrated with H6. In addition, H6 could directly stimulate P-gp ATPase activity in vitro. Importantly, H6 enhanced the efficacy of paclitaxel against KBV cancer cell-derived xenograft tumors in nude mice. Finally, H6 showed high binding affinity with P-gp with a high docking score. Overall, we show H6 is a novel and potent MDR reversal agent, which has the potential to be administered in combination with conventional anticancer drugs.