MHY1485 promotes adriamycin sensitivity in HepG2 cells by inhibiting autophagy.

MHY1485 is an mTOR activator that inhibits the autophagy process by inhibiting the fusion between autophagosomes and lysosomes. This study aimed to explore the role and mechanism of MHY1485 in hepatocellular carcinoma (HCC) and to provide an in-depth understanding of the mechanisms of autophagy regulation in relation to adriamycin (ADM) resistance, as well as the development of a molecularly targeted autophagy-modulating approach. Here, ADM was used to treat HepG2 cells and construct an ADM-resistant cell model. The HepG2/ADM cell line and HepG2 cells were treated with MHY1485 and ADM, respectively, and the proliferation and apoptosis of HCC cells were detected using CCK8, clone formation, flow cytometry, and 5-ethynyl-2'-deoxyuridine staining assays. Ki-67, mTOR phosphorylation, and LC3A expression were detected by IF staining; the expression or phosphorylation levels of autophagy-related proteins (i.e., GLUT1, PGI, PFK, END, and MTHFD2) and apoptosis-related proteins (caspase-3, caspase-8, and caspase-9) were detected by qPCR and western blotting. The number of autophagosomes was determined by monodansylcadaverine staining. Our results showed that MHY1485 can inhibit the proliferation and growth of liver cancer cells, and that MHY1485 combined with ADM can effectively inhibit the tolerance of HepG2/ADM cells to ADM and enhance the efficacy of ADM. The results of the detection of the autophagy-related protein LC3A also indicated that MHY1485 activates mTOR and can affect the phosphorylation level of ULK1, inhibit autophagy, and enhance the sensitivity of liver cancer cells to adriamycin. In summary, MHY1485 can enhance the sensitivity of adriamycin-resistant cells to adriamycin by activating mTOR and blocking the autophagy process in cells; therefore, mTOR may become a potential target for the treatment of liver cancer.

Color-dependent unidirectional scattering of a plasmonic heterodimer investigated by a dipole-dipole interference model.

In this paper, we employ an interference model of two separated electric dipoles to study the color-dependent unidirectional scattering of a plasmonic heterodimer consisting of a pair of gold and silver disks of the same size. The dipole moments in such a dipole-dipole interference model are numerically obtained by a multipole decomposition method. It shows that the power difference between the different scattering directions predicted by the dipole-dipole interference model agrees well with that calculated by the full wave simulation. The dipole-dipole interference model indicates that the scattering directionality of the heterodimer is intimately related to its geometrical parameters, including the height and radius of the disk as well as the distance between two disks. We further show that the color routing of such a heterodimer is also maintained when an electric or magnetic dipole source is positioned in the center of the heterodimer. Finally, we propose an approach to enhance bidirectional scattering by arranging the heterodimer in a line and then the main lobe beamwidth can be reduced to about 26 deg for the right scattering and 29 deg for the left scattering. Our results may be used in designing integrated plasmonic nanocircuits that demand light guiding and routing in nanoscale.

The Relationship Between Magnetism and Microstructure of Ethylene Pyrolysis Furnace Tubes after a Long-term Service.

The magnetism and microstructure of Cr25Ni35Nb and Cr35Ni45Nb alloy tubes after 5 years of service were investigated in this paper. The saturation magnetization of the Cr25Ni35Nb alloy tube in the thickness direction is more than 20 emu/g, and the tube becomes ferromagnetic. The inner and outer walls of Cr35Ni45Nb alloy tubes also become ferromagnetic. But the saturation magnetization of the Cr35Ni45Nb alloy tubes approaches to zero in the center zone. The primary carbides M7C3 and NbC are changed into M23C6 and G phase at the outer region of the furnace tube. However, the M23C6-type carbides were replaced by carbon-rich carbides M7C3 at the carburization zone. Cr-depleted zones are formed at the inner and outer walls of the furnace tubes owing to oxidation. Carburization and oxidation reduce the Cr content of the matrix. Accordingly, the saturation magnetization is very high at the carburization zone and Cr-depleted zone. The magnetism of Cr25Ni35Nb and Cr35Ni45Nb alloy tubes has a high correlation with the Cr content of the matrix. Carburization and oxidation are the main reasons that make the paramagnetic ethylene pyrolysis furnace tube change to ferromagnetic.

Identification of two lineages of host-associated eriophyoid mites predisposed to different levels of host diversification.

Herbivorous arthropods can diversify as a consequence of evolutionary changes in response to their plant hosts. Current patterns of host association of herbivores are likely to reflect a long evolutionary history of herbivore-plant co-evolution. Here, we used molecular phylogenetics to track the evolutionary history of host shifts and diversification of 66 eriophyoid mites (Acari, Eriophyoidea), and linked past patterns of evolutionary diversification to more recent patterns of divergence by tracking population genetic variation in 13 of the eriophyoid mite species feeding on different gymnosperm hosts. This allowed us to explore the relationship between a past history of diversification and the current potential of mites to undergo host range shifts. We found that population-level diversity across gymnosperm hosts as measured by 28S rRNA markers was greater in species from the mite clade that had radiated across evolutionary time to utilize a variety of hosts including angiosperms, compared to species from the clade that has remained restricted to ancestral gymnosperm hosts. Species from the radiated clade exhibited higher variation in host use. Lineages of mites that have in the past been able to radiate and adapt to diverse plants may therefore be predisposed to continue their expansion on new hosts, although additional clades need to be tested.

DNA barcoding reveals the protogyne and deutogyne of Tegolophus celtis sp. nov. (Acari: Eriophyidae).

A few eriophyoid mites have two forms of adult female, called protogyne and deutogyne. The latter form is thought to increase survival under unfavorable conditions. The two forms have distinct morphological characters, which often cause them to be recognized as different species. Molecular species delimitation provides a useful tool to solve these misunderstandings. Here we describe a new species of eriophyoid mite, Tegolophus celtis sp. nov., that has protogyne and deutogyne forms infesting Chinese hackberry, Celtis sinensis Pers. (Cannabaceae), an ornamental tree in China. The two forms can be easily differentiated by body shape (fusiform and triangular, respectively) and body color (light yellow and red, respectively). The putative protogyne and deutogyne forms of T. celtis were identified by using fragments of three genes, a mitochondrial gene (COI) and two nuclear genes (18S rRNA and 28S rRNA). Kimura-2-parameter distances of these three fragmental sequences were between 0.0% and 0.9%. Phylogenetic topologies strongly support the occurrence of the protogyne and deutogyne forms with high bootstrap and Bayesian values. The population structure of T. celtis changed with the seasons, with deutogynes being most abundant in summer and protogynes being most abundant in spring. The new species described herein are vagrants on their host plants.

Environmental RNA metabarcoding for ballast water microbial diversity: Minimizing false positives.

While maritime transport boosts global trade by shipping bulk goods, it raises concerns about the spread of harmful bacteria via ballast water. Moreover, the dark and cold environments of ballast tanks often harbor extracellular DNA from dead organisms, leading to false positives in traditional environmental DNA (eDNA) metabarcoding analyses. Here, we alternatively employed environmental RNA (eRNA) metabarcoding to assess its potential for reducing false positive in ballast water monitoring. We collected eDNA and eRNA in parallel from ballast water before and after disinfection in three vessels. High-throughput sequencing of the 16S rRNA V4-V5 regions and cDNA counterparts was conducted to compare bacterial community composition. Our findings showed that over 80 % of the top 150 abundant amplicon sequence variants (ASVs) were detected by both eRNA and eDNA metabarcoding. Samples sequenced separately using DNA and RNA consistently clustered together, indicating similar community recovery efficacy. However, 42 % of ASVs were detected exclusively in DNA, resulting in significantly higher bacterial diversity compared to RNA, which suggests false positives in the DNA method. In treated samples with higher dead cell counts, the RNA method showed significantly lower bacterial diversity, indicating its effectiveness in detecting live bacteria. In summary, eRNA metabarcoding offers comparable recovery efficiency while maintaining a lower false-positive rate than eDNA metabarcoding.

Eriophyoid mites from Northeast China (Acari: Eriophyoidea).

We describe and illustrate herein one new genus and eighteen new eriophyoid mite species (Acari: Eriophyoidea) collected in northeast China. They are: Shevtchenkella huzhongiensis sp. nov. on Ulmus davidiana Planch. var. japonica (Sarg. ex Rehder) Nakai (Ulmaceae), Shevtchenkella jingboicus sp. nov. on Acer sp. (Aceraceae), Calepitrimerus flexuosus sp. nov. on Spiraea flexuosa Fisch. ex Cambess. (Rosaceae), Calepitrimerus maximowiczii sp. nov. on Crataegus maximowiczii Schneid. (Rosaceae), Calepitrimerus pilosus sp. nov. on Agrimonia pilosa Ledeb. (Rosaceae), Calepitrimerus yichunensis sp. nov. on Sorbaria sorbifolia (L.) A.Br. (Rosaceae), Cupacarus oxyphyllus sp. nov. on Euonymus oxyphyllus Miq. (Cel-astraceae), Epitrimerus sambucus sp. nov. on Sambucus williamsii Hance (Caprifoliaceae), Epitrimerus wuyingensis sp. nov. on Acer sp. (Aceraceae), Longisolenidionus amurensis gen. nov & sp. nov. on Tilia amurensis Rupr. (Tiliaceae), Phyllocoptes jiagedaqiensis sp. nov. on Cunninghamia sp. (Taxodiaceae), Aculops huzhongensis sp. nov. on Salix sp. (Sali-caceae), Aculus huzhongsalixus sp. nov. on Salix sp. (Salicaceae), Tetra angelica sp. nov. on Angelica sp. (Apiaceae), Tetra jiagedaqia sp. nov. on Lespedeza sp. (Fabaceae), Vittacus mandshurica sp. nov. on Corylus sieboldiana Blume var. mandshurica (Maxim.) C. K. Schneid. (Betulaceae), Vittacus cannabus sp. nov. on Cannabis sativa L. (Moraceae), and Peralox dentatis sp. nov. on Ulmus sp. (Ulmaceae). Two species formerly assigned to Rhyncaphytoptus, R. abiesis (Xue, Song & Hong, 2006) and R. fabris (Xue, Song & Hong, 2006) were reassigned to Nalepella, based on the presence of seta vi on the apical shield, and other characteristics of Nalepella. One species formerly assigned to Rhyncaphytoptus, R. fargesis (Xue, Song & Hong, 2006) was reassigned to Pentaporca, based on the presence of seta vi on the apical shield, opisthosoma with five ridges and other characteristics of Pentaporca. At the same time, four new eriophyoid mite records from China are provided, Acaphyllisa distasa (Keifer, 1961) rec. nov. on Betula costata Trautv. (Betulaceae), Shevtchenkella ulmi (Farkas, 1960) rec. nov. on Ulmus sp. (Ulmaceae), Calepitrimerus cariniferus Keifer, 1938, rec. nov. on Artemisia argyi H. Lev. & Vaniot (Asteraceae), Aculodes dubius (Nalepa, 1891) species complex, rec. nov. on Roegneria sp. (Poaceae). With this publication, the number of eriophyoid mite species in the region reaches 101. A list of these eriophyoid mites is provided.

An Improved Adam Optimization Algorithm Combining Adaptive Coefficients and Composite Gradients Based on Randomized Block Coordinate Descent.

An improved Adam optimization algorithm combining adaptive coefficients and composite gradients based on randomized block coordinate descent is proposed to address issues of the Adam algorithm such as slow convergence, the tendency to miss the global optimal solution, and the ineffectiveness of processing high-dimensional vectors. The adaptive coefficient is used to adjust the gradient deviation value and correct the search direction firstly. Then, the predicted gradient is introduced, and the current gradient and the first-order momentum are combined to form a composite gradient to improve the global optimization ability. Finally, the random block coordinate method is used to determine the gradient update mode, which reduces the computational overhead. Simulation experiments on two standard datasets for classification show that the convergence speed and accuracy of the proposed algorithm are higher than those of the six gradient descent methods, and the CPU and memory utilization are significantly reduced. In addition, based on logging data, the BP neural networks optimized by six algorithms, respectively, are used to predict reservoir porosity. Results show that the proposed method has lower system overhead, higher accuracy, and stronger stability, and the absolute error of more than 86% data is within 0.1%, which further verifies its effectiveness.

Exploring the bacterial diversity and composition with special emphasis on pathogens in ship ballast water and sediments using full-length 16S rRNA gene sequencing.

Accurate detecting bacterial communities in ballast water and sediments supports risk management. This study uses full-length 16S rRNA gene sequencing to investigate the bacterial communities in ballast water and sediments, focusing on detecting pathogens. The results indicate that full-length sequencing more accurately reveals the species diversity. There is a significant difference (P < 0.05) in bacterial communities between ballast water and sediments, despite both being dominated by the Proteobacteria phylum. Thirty human and fish pathogens were identified by full-length sequencing, yet only five pathogens were detected from V3-V4 sequencing. Notably, emerging pathogens such as Citrobacter freundii and Nocardia nova are detected in samples, which are harmful to aquaculture and human health. Several opportunistic pathogens were also identified. In summary, this study provides important insights into the bacterial communities in ballast water and sediments, highlighting the need for strict management.

An improved two-stage label propagation algorithm based on LeaderRank.

To solve the problems of poor stability and low modularity (Q) of community division results caused by the randomness of node selection and label update in the traditional label propagation algorithm, an improved two-stage label propagation algorithm based on LeaderRank was proposed in this study. In the first stage, the order of node updating was determined by the participation coefficient (PC). Then, a new similarity measure was defined to improve the label selection mechanism so as to solve the problem of label oscillation caused by multiple labels of the node with the most similarity to the node. Moreover, the influence of the nodes was comprehensively used to find the initial community structure. In the second stage, the rough communities obtained in the first stage were regarded as nodes, and their merging sequence was determined by the PC. Next, the non-weak community and the community with the largest number of connected edges were combined. Finally, the community structure was further optimized to improve the modularity so as to obtain the final partition result. Experiments were performed on nine classic realistic networks and 19 artificial datasets with different scales, complexities, and densities. The modularity and normalized mutual information (NMI) were used as evaluation indexes for comparing the improved algorithm with dozens of relevant classic algorithms. The results showed that the proposed algorithm yields superior performance, and the results of community partitioning obtained using the improved algorithm were stable and more accurate than those obtained using other algorithms. In addition, the proposed algorithm always performs well in nine large-scale artificial data sets with 6,000 to 50,000 nodes and three large realistic network datasets, which verifies its computational performance and utility in community detection for large-scale networks.

Hotel Review Classification Based on the Text Pretraining Heterogeneous Graph Neural Network Model.

With the amount of online information continuously growing, it becomes more and more important for online stores to recommend corresponding products precisely based on users' preferences. Reviews for various products can be of great help for the recommendation task. However, most recommendation platforms only classify positive and negative reviews based on sentiment analysis, without considering the actual demands of users, and it will reduce the effectiveness on classification task. To count this issue, we propose a new model, which integrates heterogeneous neural network and text pretraining model into this task, and compare this model with others on a travel type classification task. The model combines a pretrained text model named Bidirectional Encoder Representation from Transformers (BERT) and heterogeneous graph attention network (HGAN). Firstly, we do a fine-tuning task on BERT by a dataset consisting of 1.4 million hotel reviews from the Ctrip website to obtain fine representations of trip-related words. Then, we proposed the similarity fussy-matching method to get the main topic of each review. Then, we construct a heterogeneous neural network and apply the attention mechanism to it to mine the preference of users for traveling. Finally, the classification task is done based on each user's preference. In Section 5 of this study, we do an experiment, which compares our model with five others. The results show that the accuracy of ours is 70%, which is higher than the other five models.

A phase II trial of docetaxel plus nedaplatin and 5-fluorouracil in treating advanced esophageal carcinoma.

BACKGROUND AND OBJECTIVE: Accumulating data indicate that docetaxel plus cisplatin and 5-fluorouracil has certain effect on advanced gastric or gastro-oesophageal junction adenocarcinoma. This study was to evaluate the efficacy and toxicity of docetaxel plus nedaplatin and 5-fluorouracil (DNF regimen) in treating advanced esophageal carcinoma. METHODS: Forty-three patients with pathologically confirmed advanced esophageal carcinoma treated by DNF regimen: intravenous infusion of docetaxel (75 mg/m(2)) over 1 h, intravenous infusion of nedaplatin (100 mg/m(2)) over 3 h, intravenous infusion of leucovorin (CF, 200 mg/m(2)) over 2 h, intravenous injection of 5-fluorouracil (375 mg/m(2)) over 10 min, followed by a 46-hour infusion of 5-fluorouracil (2.6 g/m(2)). The cycle was repeated every three weeks. Treatment efficacy was evaluated every two weeks according to the WHO standards. All patients received at least two cycles of chemotherapy. RESULTS: Patients received a total of 144 cycles of treatment, and all were evaluable for efficacy and toxicity. Of the 43 patients, 2 (4.65%) achieved complete response (CR), 25 (58.14%) achieved partial response (PR), 9 (20.93%) had stable disease (SD), and 7 (16.28%) had progressive disease (PD). The overall response rate was 62.8%. The median time-to-progression (TTP) was 201 days and the median survival time (MST) was 310 days. Grade III/IV adverse events mainly included neutropenia (20.93%), febrile neutropenia (4.65%), thrombocytopenia (6.98%) and vomiting (9.30%). One patient died of grade IV thrombocytopenia. CONCLUSION: DNF regimen is effective for and well tolerated by patients with advanced esophageal carcinoma.

Cardiac VFM visualization and analysis based on YOLO deep learning model and modified 2D continuity equation.

In order to realize the visual analysis of cardiac fluid motion, according to the characteristics of cardiac flow field ultrasound image, a method for the cardiac Vector Flow Mapping (VFM) analysis and evaluation based on the You-Only-Look-Once (YOLO) deep learning model and the improved two-dimensional continuity equation is proposed in this paper. Firstly, based on the ultrasound Doppler data, the radial velocity values of the blood particles are obtained; due to the real-time VFM's high requirement on the computing speed, the YOLO deep learning model is combined with an improved block matching algorithm for the localization and tracking of myocardial wall, and then the azimuth velocity of myocardial wall speckles can be obtained; in addition, it is proposed in this paper to use a nonlinear weight function to fuse the radial velocity of the blood particles and azimuth velocity of myocardial wall speckles nonlinearly, and further the vortex streamline diagram in the cardiac flow field can be obtained. The results of the experiments on the evaluation of the Ultrasonic apical long-axis view show that the proposed method not only improves the accuracy of VFM, but also provides a new evaluation basis for cardiac function impairment.

Body mass index and exon 19 mutation as factors predicting the therapeutic efficacy of gefitinib in patients with epidermal growth factor receptor mutation-positive non-small cell lung cancer.

BACKGROUND: Many randomized clinical trials have demonstrated that epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are advantageous over standard chemotherapy, either as front-line treatment or as further management of patients with EGFR mutation-positive non-small-cell lung cancer (NSCLC). However, which subgroup of these patients could benefit more from EGFR-TKIs needs to be further explored. In the present study, we explored the predictive factors in such cohorts of patients who received gefitinib. METHODS: The study included 95 patients with EGFR mutation-positive advanced NSCLC who received gefitinib treatment. Multivariate analysis of progression-free survival (PFS) was performed using classification and regression tree (CART) analysis to assess the effect of specific variables on PFS in subgroups of patients with similar clinical features. RESULTS: The median PFS in patients with EGFR mutation-positive advanced NSCLC who received gefitinib treatment was 13.3 months (95% confidence interval 9.4-17.2). CART analysis showed an initial split on body mass index (BMI); subsequently, three terminal subgroups were formed. The median PFS in the three subsets ranged from 8.2 to 15.2 months, in which the subgroup with a BMI less than or equal to 20.8 kg/m(2) had the longest PFS (15.2 months). In addition, PFS in the EGFR exon 19 mutation group was better than in the other mutation site group (10.3 vs. 8.2 months). CONCLUSIONS: BMI and exon 19 mutation may be predictors of PFS in patients with EGFR mutation-positive advanced NSCLC who receive gefitinib treatment. Both active EGFR mutation and patient-specific factors may be used to predict the therapeutic efficacy of EGFR-TKIs.

Mitochondrial genome evolution and tRNA truncation in Acariformes mites: new evidence from eriophyoid mites.

The subclass Acari (mites and ticks) comprises two super-orders: Acariformes and Parasitiformes. Most species of the Parasitiformes known retained the ancestral pattern of mitochondrial (mt) gene arrangement of arthropods, and their mt tRNAs have the typical cloverleaf structure. All of the species of the Acariformes known, however, have rearranged mt genomes and truncated mt tRNAs. We sequenced the mt genomes of two species of Eriophyoidea: Phyllocoptes taishanensis and Epitrimerus sabinae. The mt genomes of P. taishanensis and E. sabinae are 13,475 bp and 13,531 bp, respectively, are circular and contain the 37 genes typical of animals; most mt tRNAs are highly truncated in both mites. On the other hand, these two eriophyoid mites have the least rearranged mt genomes seen in the Acariformes. Comparison between eriophyoid mites and other Aacariformes mites showed that: 1) the most recent common ancestor of Acariformes mites retained the ancestral pattern of mt gene arrangement of arthropods with slight modifications; 2) truncation of tRNAs for cysteine, phenylalanine and histidine occurred once in the most recent common ancestor of Acariformes mites whereas truncation of other tRNAs occurred multiple times; and 3) the placement of eriophyoid mites in the order Trombidiformes needs to be reviewed.

Classification and regression tree analysis of patients with non-small-cell lung cancer treated with gefitinib after chemotherapy.

BACKGROUND: Many randomized studies have shown that epidermal growth factor receptor (EGFR-) tyrosine kinase inhibitors (TKIs) are apparently advantageous over standard chemotherapy in non-small-cell lung cancer (NSCLC) patients with EGFR active mutation in front-line treatment. But which subgroup of advanced NSCLC could benefit from EGFR-TKIs in the second-or third-line setting remains elusive. To explore predictive factors of advanced NSCLC patients with the unknown status of EGFR mutation treated by gefitinib in the second-or third-line setting, we used classification and regression tree (CART) analysis to screen which patients would benefit more. METHODS: One hundred and fifty-five patients with advanced NSCLC previously unsuccessfully treated with platinum-based chemotherapy were included in this study. Patients received gefitinib as part of the Expanded Access Program of the China Charity Federation between 2 March 2005 and 11 May 2011. Multivariate analysis of progression-free survival (PFS) was performed using CART analysis. This method uses recursive partitioning to assess the effect of specific variables on PFS, thereby ultimately generating groups of patients with similar clinical features on PFS. RESULTS: The median PFS in patients with NSCLC who were treated with gefitinib after prior chemotherapy was 16 months (95% confidence interval [CI] 13.44-18.56). CART was performed with an initial split on adenocarcinoma differentiation, and four terminal subgroups were formed. The median PFS of the four subsets ranged from 12 to 42 months. CONCLUSIONS: Adenocarcinoma differentiation, brain metastasis and prior thoracic radiotherapy are predictors of PFS in previously treated NSCLC patients. CART can be used to identify homogeneous patient populations in clinical practice and future clinical trials.

Rhabdastrellic acid-A induced autophagy-associated cell death through blocking Akt pathway in human cancer cells.

BACKGROUND: Autophagy is an evolutionarily conserved protein degradation pathway. A defect in autophagy may contribute to tumorigenesis. Autophagy inducers could have a potential function in tumor prevention and treatment. METHODOLOGY/PRINCIPAL FINDINGS: Our results showed that Rhabdastrellic acid-A, an isomalabaricane triterpenoid isolated from the sponge Rhabdastrella globostellata, inhibited proliferation of human cancer cell lines Hep3B and A549 and induced caspase-independent cell death in both the cell lines. Further investigation showed that Rhabdastrellic acid-A induced autophagy of cancer cells determined by YFP-LC3 punctation and increased LC3-II. The pretreatment with autophagy inhibitor 3-MA inhibited Rhabdastrellic acid-A-induced cell death. Knockdown of autophagy-related gene Atg5 inhibited Rhabdastrellic acid-A-induced cell death in A549 cells. Also, phospho-Akt and its downstream targets significantly decreased after treatment with Rhabdastrellic acid-A in both cancer cell lines. Transfection of constitutive active Akt plasmid abrogated autophagy and cell death induced by Rhabdastrellic acid-A. CONCLUSIONS/SIGNIFICANCE: These results suggest that Rhabdastrellic acid-A could induce autophagy-associated cell death through blocking Akt pathway in cancer cells. It also provides the evidence that Rhabdastrellic acid-A deserves further investigation as a potential anticancer or cancer preventive agent.

Rhabdastrellic acid-A inhibited PI3K/Akt pathway and induced apoptosis in human leukemia HL-60 cells.

Increasing evidence suggests that aberrant activation of PI3K/Akt is involved in many human cancers, and that inhibition of the PI3K/Akt pathway might be a promising strategy for cancer treatment. Our investigation indicates that Rhabdastrellic acid-A, an isomalabaricane triterpenoid isolated from the sponge, Rhabdastrella globostellata, inhibits proliferation of HL-60 cells with an IC(50) value of 0.68mug/ml, and induces apoptosis. Rhabdastrellic acid-A also induces cleavage of the death substrate poly (ADP-ribose) polymerase (PARP) and caspase-3. Pretreatment of HL-60 cells with the caspase-3 specific inhibitor, DEVD-CHO, prevents Rhabdastrellic acid-A-induced DNA fragmentation and PARP cleavage. Activated PI3K and Akt significantly decreases after treatment with Rhabdastrellic acid-A in HL-60 cells. Expression levels of protein bcl-2, bax remain unchanged in response to Rhabdastrellic acid-A treatment in HL-60 cells. These results suggest that Rhabdastrellic acid-A inhibits PI3K/Akt pathway and induces caspase-3 dependent-apoptosis in HL-60 human leukemia cells.

[Apoptosis of human leukemia HL-60 cells induced by rhabdastrellic acid-A and its mechanisms].

BACKGROUND & OBJECTIVE: Rhabdastrellic acid-A is an isomalabaricane triterpenoid isolated from the sponge Rhabdastrella globostellata from South China Sea. Our previous study indicated that rhabdastrellic acid-A can inhibit the proliferation of many types of tumor cells with minor toxicity. This study was to investigate the apoptosis of human leukemia HL-60 cells induced by rhabdastrellic acid-A and its possible mechanisms. METHODS: Inhibitory effect of rhabdastrellic acid-A on the proliferation of HL-60 cells was evaluated by MTT assay. DNA fragmentation was analyzed by agarose electrophoresis. Cell morphology was observed under fluorescent microscope. The protein levels of Caspase-3, poly(ADP-ribose) polymerase (PARP), P73, Bcl-2 and Bax were analyzed by Western blot. The expression profile of apoptosis-related genes was analyzed by gene microarray. Reverse transcription-polymerase chain reaction (RT-PCR) was conducted to confirm some altered genes identified by gene microarray. RESULTS: Rhabdastrellic acid-A inhibited the proliferation of HL-60 cells and the 50% inhibition concentration (IC50) was (0.64+/-0.21) microg/ml. When treated with 1 microg/ml rhabdastrellic acid-A for 36 h, condensation of nuclear chromatin of HL-60 cells was observed under fluorescent microscope and DNA fragmentation was observed by agarose electrophoresis. Also, rhabdastrellic acid-A induced cleavage of PARP and Caspase-3. The mRNA levels of 44 genes, including p73, JunD, TNFAIP3 and GADD45A, were up-regulated and the mRNA levels of 16 genes, including MAP2K5 and IGF2R, were down-regulated. The results were further confirmed by RT-PCR. The protein level of P73 was up-regulated after rhabdastrellic acid-A treatment. CONCLUSION: Rhabdastrellic acid-A could induce the apoptosis of HL-60 cells which may be related to the up-regulation of apoptosis-related genes such as p73 and JunD, and the down-regulation of MAP2K5 and IGF2R.