Cell cycle modulatory effects of Amaryllidaceae alkaloids

Narciclasine, a novel topoisomerase I inhibitor, exhibited potent anti-cancer activity against cancer cells

DNA topoisomerases are essential nuclear enzymes in correcting topological DNA errors and maintaining DNA integrity. Topoisomerase inhibitors are a significant class of cancer chemotherapeutics with a definite curative effect. Natural products are a rich source of lead compounds for drug discovery, including anti-tumor drugs. In this study, we found that narciclasine (NCS), an amaryllidaceae alkaloid, is a novel inhibitor of topoisomerase I (topo I). Our data demonstrated that NCS inhibited topo I activity and reversed its unwinding effect on p-HOT DNA substrate. However, it had no obvious effect on topo II activity. The molecular mechanism of NCS inhibited topo I showed that NCS did not stabilize topo-DNA covalent complexes in cells, indicating that NCS is not a topo I poison. A blind docking result showed that NCS could bind to topo I, suggesting that NCS might be a topo I suppressor. Additionally, NCS exhibited a potent anti-proliferation effect in various cancer cells. NCS arrested the cell cycle at G2/M phase and induced cell apoptosis. Our study reveals the antitumor mechanisms of NCS and provides a good foundation for the development of anti-cancer drugs based on topo I inhibition.

Synthesis and biological evaluation of novel pteridin-7(8H)-one derivatives as potent CDK2 inhibitors

Cyclin-dependent kinase 2 (CDK2) is considered as an important target in the research of antitumor drugs. Taking the CDK2/4/6 inhibitor Ebvaciclib as the positive control and an in-house library compound (23) as the lead compound, three classes of 30 target compounds with pteridin-7(8H)-one as the core structure were designed to establish structure-activity relationships (SAR). In general, SAR of pteridin-7(8H)-one CDK2 inhibitors is systematically described in this paper, resulting in the discovery of two compounds (KII-17 and KII-21) with further research value. After the above compounds were tested for CDK2/4/6 kinase selectivity, we found that compound KII-21 was about 3 and 4 times more selective to CDK2-cyclinE2 than CDK4-cyclinD1 and CDK6-cyclinD3, respectively. This work also provides a reference basis for the subsequent research on CDK2 inhibitors.

Design, synthesis and biological evaluation of liposome entrapped iridium(III) complexes toward SGC-7901 cells

In this study, two new iridium(III) polypyridyl complexes [Ir(bzq)₂(DIPH)](PF₆) (bzq = deprotonated benzo[h]quinoline, DIPH = 4-(2,5-dibromo-4-(1H-imidazo[4,5-f][1,10]phenanthrolim-2-yl)-4-hydroxybutan-2-one) (Ir1) and [Ir(piq)₂(DIPH)](PF₆) (piq = deprotonated 1-phenylisoquinoline) (Ir2) were synthesized and characterized by elemental analysis, HRMS, ¹H and ¹³C NMR. The cytotoxic activity of Ir1, Ir2, Ir1lipo and Ir2lipo against cancer cells SGC-7901, HepG2, A549, HeLa, B16 and normal NIH3T3 cells in vitro was evaluated using 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide (MTT) method. Ir1 and Ir2 showed no cytotoxic activity, but their liposome-entrapped Ir1 (Ir1lipo) and Ir2 (Ir2lipo) showed significant cellular activity, especially sensitive to SGC-7901 with IC₅₀ values of 4.7 ± 0.2 and 12.4 ± 0.5 μM, respectively. The cellular uptake, endoplasmic reticulum (ER) localization, autophagy, tubulin polymerization, glutathione (GSH), malondialdehyde (MDA) and release of cytochrome c were investigated to explore the mechanisms of apoptosis. The calreticulin (CRT), heat shock protein 70 (HSP70), high mobility group box 1 (HMGB1) were also explored. Western blotting showed that Ir1lipo and Ir2lipo inhibited PI3K (phosphoinositide-3 kinase), AKT (protein kinase B), p-AKT and activated Bcl-2 (B-cell lymphoma-2) protein and apoptosis-regulated factor caspase 3 (cysteinyl aspartate specific proteinase-3) and cleaving PARP (poly ADP-ribose polymerase). The results demonstrated that Ir1lipo and Ir2lipo induce cell apoptosis through targeting the endoplasmic reticulum (ER), cause oxidative stress damage, inhibiting PI3K/AKT signaling pathway, immunogenic cell death (ICD) and inhibit the cell growth at G2/M phase.

Enantio- and Regioselective Electrooxidative Cobalt-Catalyzed C-H/N-H Annulation with Alkenes

In recent years, the merging of electrosynthesis with 3d metal catalyzed C-H activation has emerged as a sustainable and powerful technique in organic synthesis. Despite the impressive advantages, the development of an enantioselective version remains elusive and poses a daunting challenge. Herein, we report the first electrooxidative cobalt-catalyzed enantio- and regioselective C-H/N-H annulation with olefins using an undivided cell at room temperature (up to 99 % ee). ^t Bu-Salox, a rationally designed Salox ligand bearing a bulky tert-butyl group at the ortho-position of phenol, was found to be crucial for this asymmetric annulation reaction. A strong cooperative effect between ^t Bu-Salox and 3,4,5-trichloropyridine enabled the highly enantio- and regioselective C-H annulation with the more challenging α-olefins without secondary bond interactions (up to 96 % ee and 97 : 3 rr). Cyclovoltametric studies, and the preparation, characterization, and transformation of cobaltacycle intermediates shed light on the mechanism of this reaction.

A water-soluble polysaccharide from Eucommia folium: the structural characterization and anti-tumor activity in vivo

In this study, a water-soluble polysaccharide from Eucommia folium was extracted by hot water and purified using Sephadex G-200 gel columns. The results showed that the purified fraction (EFP) has a molecular weight of 9.98 × 10⁵ Da and consisted of rhamnose, arabinose, galactose, glucose, mannose, xylose, galacturonic acid, and glucuronic acid (molar ratio: 0.226: 1.739: 2.183: 1: 0.155: 0.321: 0.358: 0.047). The combination of infrared spectroscopy and NMR analysis proved that EFP is an acidic polysaccharide whose main chain consists of α-L-Araf-(1 → , → 3,5)-α-Araf-(1 → , → 3)-β-Galp-(1 → , → 3,6)-β-Glcp-(1 → , → 2)-α-D-Manp-(1 → , → 4)-α-GalpA-(1 → , → 2,4)-α-Rhap-(1 → . In addition, the in vivo antitumoral activity of EFP was studied using a H22 tumor-bearing mice model. EFP effectively inhibited tumor growth in mice following intragastric administration. By Combining with the results of the apoptosis assay and JC-1 staining analysis, we confirmed that EFP induces apoptosis through the mitochondrial pathway. Furthermore, cell cycle analysis demonstrated that EFP blocks the cell cycle at S phase.

β-Carboline dimers inhibit the tumor proliferation by the cell cycle arrest of sarcoma through intercalating to Cyclin-A2

β-Carbolines are potentially strong alkaloids with a wide range of bioactivities, and their dimers exhibit stronger antitumor activity other than the monomers. However, the detailed mechanisms of the β-carboline dimers in inhibiting sarcoma (SARC) remain unclear. The results showed that β-carboline-3-carboxylic acid dimers Comp1 and Comp2, which were synthesized in our lab and modified at the N⁹ position and linked at the C³ position, exhibited effective inhibition activity on MG-63 proliferation (IC_{50 =} 4.6μM). Meanwhile, the large scale transcriptome profiles of SARC from The Cancer Genome Atlas (TCGA) were analyzed, and found that abnormal expression of genes relevant to apoptosis, cell cycle, and signaling pathways of Hedgehog, HIF, Ras involved in the SARC pathogenesis. Interestingly, both dimers could promote the apoptosis and arrest the cell cycle in S phase to inhibit proliferation of MG-63. Moreover, Comp1 and Comp2 inhibited the expression CDK2, CCNA2, DBF4, and PLK1 associated with various immune cells and cell cycle in MG-63. Remarkably, drug-target interaction network analysis showed that numerous proteins involved in cell cycle were the potential targets of Comp1 and Comp2, especially CCNA2. Further molecular docking, isothermal titration calorimetry (ITC) and Cellular Thermal Shift Assay (CETSA) confirmed that both dimers could directly interact with CCNA2, which is significantly correlated with CD4+ T cells, by strong hydrophobic interactions (K_d=5.821 ×10⁶ N). Meanwhile, the levels of CCNA2 and CDK2 were inhibited to decrease in MG-63 by both dimer treatments at transcription and protein levels, implying that Comp1 and Comp2 blocked the interaction between CCNA2 and CDK2 through competitive binding with CCNA2 to arrest the cell cycle of MG-63 cells in the S phase. Additionally, the transcriptome profiles of β-carboline-treated mice from Gene Expression Omnibus (GEO) were obtained, and found that similar antitumor mechanism was shared among β-carboline derivatives. Overall, our results elucidated the antitumor mechanisms of Comp1 and Comp2 through dual-suppressing the function of CCNA2 to profoundly arrest cell cycle of MG-63, then effectively inhibited cell proliferation of MG-63. These results provide new insights into the antitumor mechanism of β-carboline dimers and new routes of various novel cancer-related drug targets for future possible cancer therapy.

Advances in the research of plant-derived natural products against retinoblastoma

Retinoblastoma (RB) is a highly aggressive ocular tumor, and due to socioeconomic and medical constraints, many children receive treatment only in the metaphase and advanced clinical stages, resulting in high rates of blindness and disability. Although several approaches exist in the treatment of RB, some children with the disease do not have satisfactory results because of various factors. Plant-derived natural products have shown definite therapeutic effects in the treatment of various tumors and are also widely used in the study of RB. We review plant-derived natural products used in the study of anti-RB to provide ideas for the clinical application of these drugs and the development of new therapeutic drugs.

The Structural Characteristics of an Acidic Water-Soluble Polysaccharide from Bupleurum chinense DC and Its In Vivo Anti-Tumor Activity on H22 Tumor-Bearing Mice

This study explored the preliminary structural characteristics and in vivo anti-tumor activity of an acidic water-soluble polysaccharide (BCP) separated purified from Bupleurum chinense DC root. The preliminary structural characterization of BCP was established using UV, HPGPC, FT-IR, IC, NMR, SEM, and Congo red. The results showed BCP as an acidic polysaccharide with an average molecular weight of 2.01 × 10³ kDa. Furthermore, we showed that BCP consists of rhamnose, arabinose, galactose, glucose, and galacturonic acid (with a molar ratio of 0.063:0.788:0.841:1:0.196) in both α- and β-type configurations. Using the H22 tumor-bearing mouse model, we assessed the anti-tumor activity of BCP in vivo. The results revealed the inhibitory effects of BCP on H22 tumor growth and the protective actions against tissue damage of thymus and spleen in mice. In addition, the JC-1 FITC-AnnexinV/PI staining and cell cycle analysis have collectively shown that BCP is sufficient to induce apoptosis and of H22 hepatocarcinoma cells in a dose-dependent manner. The inhibitory effect of BCP on tumor growth was likely attributable to the S phase arrest. Overall, our study presented significant anti-liver cancer profiles of BCP and its promising therapeutic potential as a safe and effective anti-tumor natural agent.

Hohenbuehelia serotina polysaccharides self-assembled nanoparticles for delivery of quercetin and their anti-proliferative activities during gastrointestinal digestion in vitro

In this study, the self-assembled nanoparticles based on Hohenbuehelia serotina polysaccharides (QC-HSP NPs) were fabricated to encapsulate quercetin for improving its bioavailability. The structural characteristics, physicochemical properties as well as the cytotoxicity activities of QC-HSP NPs during gastrointestinal digestion in vitro were respectively investigated. The results showed that QC-HSP NPs possessed the spherical and smooth surface morphology, with the average particle size of 360 nm and zeta potential of -38.8 mV. Moreover, QC-HSP NPs had excellent physiochemical stabilities, and presented sustained-release characteristics during gastrointestinal digestion in vitro. Compared with undigested ones, QC-HSP NPs after gastrointestinal digestion exhibited the more significant anti-proliferative activity on HeLa cells through accumulation of intracellular ROS, arrest of cell cycle at G2/M phase by regulation of cyclin B1, CDK1, p53 and p21 and induction of apoptosis by ER apoptosis pathway. This study provides a new strategy for designing quercetin-loaded nanoparticles based on natural polysaccharides to improve the bioavailability of quercetin.

Alkaloids of Phaedranassa dubia (Kunth) J.F. Macbr. and Phaedranassa brevifolia Meerow (Amaryllidaceae) from Ecuador and its cholinesterase-inhibitory activity

Alzheimer's disease is considered the most common cause of dementia and, in an increasingly aging population worldwide, the quest for treatment is a priority. Amaryllidaceae alkaloids are of main interest because of their cholinesterase inhibition potential, which is the main palliative treatment available for this disease. We evaluated the alkaloidal profile and the in vitro inhibitory activity on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) of bulb alkaloid extract of Phaedranassa dubia and Phaedranassa brevifolia collected in Ecuador. Using gas chromatography coupled to mass spectrometry (GC-MS), we identified typical Amaryllidaceae alkaloids in these species, highlighting the presence of lycorine-type alkaloids in P. dubia and haemanthamine/crinine-type in P. brevifolia. The species P. dubia and P. brevifolia showed inhibitory activities against AChE (IC₅₀ values of 25.48 ± 0.39 and 3.45 ± 0.29 μg.mL^-1, respectively) and BuChE (IC₅₀ values of 114.96 ± 4.94 and 58.89 ± 0.55 μg.mL^-1, respectively). Computational experiments allowed us to understand the interactions of the alkaloids identified in these samples toward the active sites of AChE and BuChE. In silico, some alkaloids detected in these Amaryllidaceae species presented higher estimated binding free energy toward BuChE than galanthamine. This is the first study about the alkaloid profile and biological potential of P. brevifolia species.

Structural characterization of a novel polysaccharide from Pleurotus citrinopileatus and its antitumor activity on H22 tumor-bearing mice

In this research, a novel polysaccharide (PCP) was extracted from Pleurotus citrinopileatus and purified by Sephadex G-150 gel column, and its antitumor activity was investigated using the model H22 tumor-bearing mice. PCP was found to be composed of arabinose, galactose, glucose, xylose, mannose and glucuronic acid in a proportion of 0.66: 14.59: 10.77: 1: 0.69: 0.23 with average molecular weight of 7.30 × 10⁵ Da. Further analysis suggested that PCP was a pyranose with α-type and β-type glycosidic residues. The antitumor assays in vivo indicated that PCP could effectively suppress H22 solid tumor growth, protect immune organs and improve inflammation and anemia. Besides, Annexin V-FITC/PI double staining and JC-1 staining demonstrated that PCP could induce apoptosis of H22 hepatoma cells. The PI staining assay revealed that PCP induced H22 hepatoma cells apoptosis by arresting cell cycle in S phase. These results suggest that the polysaccharide from Pleurotus citrinopileatus possesses potential value in the treatment of liver cancer.

The structural characteristics of an acid-soluble polysaccharide from Grifola frondosa and its antitumor effects on H22-bearing mice

The edible mushroom G. frondosa has been used as a kind of functional food for the prevention and therapy of various diseases in Asian countries. In the present work, a novel acid-soluble polysaccharide (GFAP) was successfully isolated from G. frondosa under room temperature and hydrochloric acid solution treatment. Results of chemical composition analysis, UV and HPGPC spectra showed that GFAP mainly contained 94.28% of carbohydrate with the average molecular weight of about 644.9 kDa. GC, FT-IR, NMR and methylation analysis further indicated that GFAP was a neutral sugar mainly composed of (1 → 3)-β-D-Glcp and (1 → 3)-α-D-Manp. The in vivo antitumor experiments demonstrated that GFAP could effectively protect thymuses and spleens of tumor-bearing mice and inhibit the growth of H22 solid tumors with the inhibitory rate of 36.72%. Besides, GFAP could significantly improve the activities of NK cells, macrophages, CD19+ B cells and CD4+ T cells, leading to the apoptosis of H22 cells via G0/G1 phase arrested. Our data demonstrated that GFAP holds great application prospect to be a safe and effective antitumor adjuvant in the future.

Association and clinicopathologic significance of p38MAPK-ERK-JNK-CDC25C with polyploid giant cancer cell formation

BACKGROUND

We previously showed that cobalt chloride (CoCl₂) induction of polyploid giant cancer cells (PGCCs) was characterized by abnormal cell cycle-related protein expression and G2/M arrest. The role of the p38MAPK-ERK-JNK signaling pathway in cell cycle regulation has been reported, but the mechanism by which p38MAPK-ERK-JNK regulates PGCCs formation remains unclear. This study examined p38MAPK-ERK-JNK-CDC25C expression in PGCCs and their daughter and control cells and assessed the clinicopathological significance of p38MAPK, ERK, JNK, and CDC25C expression in human ovarian and breast cancers.

METHODS

CoCl₂ was used to induce the formation of PGCCs in HEY and BT-549 cells. Western blotting and immunocytochemical staining were used to compare the expression and subcellular localization of p38MAPK, ERK, JNK, and CDC25C in the control group and CDC25C knockdown before and after CoCl₂ treatment. The specific combination of p38MAPK and ERK with pCDC25C-Ser216 was detected by immunoprecipitation. In addition, p38MAPK, ERK, JNK, and CDC25C immunohistochemical staining were performed to compare the clinicopathologic significances in 81 cases of ovarian cancer tissue, including 20 cases of primary breast cancer with lymph node metastasis (group I), and their corresponding metastatic lymph nodes (group II), 31 cases of primary breast cancer without metastasis (group III), and 10 cases of benign breast tumors (group IV). Breast tumor tissue from 229 was divided into two groups: 167 cases of primary invasive breast cancer (group 1) and 62 cases of lymph node metastatic breast cancer (group 2).

RESULTS

Compared to the control cells, p38MAPK and JNK expression were higher and CDC25C expression was lower in CoCl₂-treated cells. Moreover, ERK displayed a trend of increased expression in HEY PGCCs and decreased expression in BT-549 PGCCs. p38MAPK and ERK regulated CDC25C by phosphorylating the CDC25C-Ser216 site and participated in the G2/M phase transition. Immunohistochemical (IHC) analysis of the ovarian tumor tissues showed significant positive staining rates of p38MAPK (P = 0.001), ERK (P = 0.002), JNK (P = 0.000), and CDC25C (P = 0.000) among the four groups. In breast tumor tissues, the overall expression in p38MAPK (P = 0.029), ERK (P = 0.002), JNK (P = 0.013), and CDC25C (P = 0.001) also differed significantly between the two groups.

CONCLUSION

The p38MAPK-ERK-JNK signaling pathway was involved in cell cycle progression and the formation of PGCCs by regulation of CDC25C.

Phytochemistry and Pharmacology of the Family Amaryllidaceae: An Overview of Research at RCPGD

Professor Johannes van Staden, Director of the Research Centre for Plant Growth and Development-University of KwaZulu Natal, conducts research in the field of plant physiology, biotechnology, and ethnomedicine. The research span over a wide range of plant families growing in the southern African region. The plant family Amaryllidaceae, known for its ornamental and pharmacological values, received much attention by his research group. This review covers research conducted by his group on the chemistry of some members of Amaryllidaceae and biological activities of their constituents.

Anti-Cancer Effects of Green Tea Polyphenols Against Prostate Cancer

Prostate cancer is the most common cancer among men. Green tea consumption is reported to play an important role in the prevention of carcinogenesis in many types of malignancies, including prostate cancer; however, epidemiological studies show conflicting results regarding these anti-cancer effects. In recent years, in addition to prevention, many investigators have shown the efficacy and safety of green tea polyphenols and combination therapies with green tea extracts and anti-cancer agents in in vivo and in vitro studies. Furthermore, numerous studies have revealed the molecular mechanisms of the anti-cancer effects of green tea extracts. We believe that improved understanding of the detailed pathological roles at the molecular level is important to evaluate the prevention and treatment of prostate cancer. Therefore, in this review, we present current knowledge regarding the anti-cancer effects of green tea extracts in the prevention and treatment of prostate cancer, with a particular focus on the molecular mechanisms of action, such as influencing tumor growth, apoptosis, androgen receptor signaling, cell cycle, and various malignant behaviors. Finally, the future direction for the use of green tea extracts as treatment strategies in patients with prostate cancer is introduced.