Polyphyllin I induces apoptosis and autophagy via modulating JNK and mTOR pathways in human acute myeloid leukemia cells

Polyphyllin I induces rapid ferroptosis in acute myeloid leukemia through simultaneous targeting PI3K/SREBP-1/SCD1 axis and triggering of lipid peroxidation

Acute myeloid leukemia (AML) is a malignant disease that is difficult to completely cure. Polyphyllin I (PPI), a steroidal saponin isolated from Paris polyphylla, has exhibited multiple biological activities. Here, we discovered the superior cytotoxicity of PPI on AML cells MOLM-13 with an IC50 values of 0.44 ± 0.09 μM. Mechanically, PPI could cause ferroptosis via the accumulation of intracellular iron concentration and triggering lipid peroxidation. Interestingly, PPI could induced stronger ferroptosis in a short time of about 6 h compared to erastin. Furthermore, we demonstrate that PPI-induced rapid ferroptosis is due to the simultaneous targeting PI3K/SREBP-1/SCD1 axis and triggering lipid peroxidation, and PI3K inhibitor Alpelisib can enhance the activity of erastin-induced ferroptosis. Molecular docking simulations and kinase inhibition assays demonstrated that PPI is a PI3K inhibitor. In addition, PPI significantly inhibited tumor progression and prolonged mouse survival at 4 mg/kg with well tolerance. In summary, our study highlights the therapeutic potential of PPI for AML and shows its unique dual mechanism.

Investigating the multifaceted cooperation of autophagy, PI3K/AKT signaling pathways, and INPP4B gene in de novo acute myeloid leukemia patients

BACKGROUND

Acute myeloid leukemia (AML) has been the most prevalent form of acute leukemia among adults, and it has been associated with poor survival rates over the last four decades. Understanding the processes involved in leukemogenesis, particularly autophagy and signaling pathways, can provide critical insights into their roles in disease development, risk assessment, and potential therapeutic interventions. This study investigated gene expression changes, focusing on MAP1LC3B and BECN1, related to autophagy, as well as PI3KCA and AKT1 in the PI3K-AKT pathway, and INPP4B, which regulates this signaling cascade.

METHODS

We collected blood samples from 21 AML patients and 9 healthy volunteers. Gene expression was analyzed through qPCR following RNA extraction and cDNA synthesis. Statistical analysis encompassed t-tests, ANOVA, and correlation coefficients.

RESULTS

AML patients exhibited significantly increased MAP1LC3B gene expression (****P < 0.0001; fold change = 11.9) and significantly reduced levels of INPP4B (****P < 0.0001; fold change = 0.026), AKT1 (*P < 0.05; fold change = 0.59), and PI3KCA (****P < 0.0001; fold change = 0.16) compared to healthy controls. However, BECN1 gene expression did not significantly differ between the two groups. Additionally, noteworthy correlations were observed between INPP4B and BECN1 (r = 0.57; P = 0.006) and BECN1 and PI3KCA (r = 0.61; P = 0.003) in AML patients.

CONCLUSIONS

This study highlights variations in leukemogenesis pathways, exemplified by increased MAP1LC3B expression and diminished expression of regulatory genes in specific AML cases. These findings contribute to our comprehension of the molecular mechanisms underlying AML and may inform future diagnostic and therapeutic approaches.

Research trends and hotspots of polyphyllin in high-incidence cancers: A bibliometric analysis

Background

Polyphyllin, a natural compound derived primarily from the Paris genus, manifests its anticancer properties. Extensive research on its therapeutic potential in cancers has been reported. However, there is no systematical analysis of the general aspects of research on polyphyllin by bibliometric analysis. The aim of this study is to visualize emerging trends and hotspots and predict potential research directions in this field.

Methods

In this study, we collected relevant research articles from the Web of Science Core Collection Bibliometrics. Using R-bibliometrix, we analyzed the research status, hotspots, frontiers, and development trends of polyphyllin in high-incidence cancers. To conduct a comprehensive visual analysis, CiteSpace and VOSviewer were used for visual analysis of authors, countries, institutions, keywords, and co-cited references within the published articles.

Results

A total of 257 articles focusing on the research of polyphyllin in high-incidence cancers were retrieved from the WOSCC database, covering the period from 2005 to 2023. The analysis revealed a consistent increasing trend in annual publications during this timeframe. Notably, China emerged as the most productive country, with Tianjin University leading the institutions. The Journal of Ethnopharmacology stood out as the most prominent journal in this field, while Gao WY emerged as the most prolific author. Polyphyllin VI, polyphyllin II, and polyphyllin VII have emerged as the latest research hotspots. Additionally, the investigation of autophagy and its associated mechanisms has gained significant attention as a novel research direction.

Conclusion

This study presents a novel visualization of the research on polyphyllin saponins in the field of highly prevalent cancers using bibliometric analysis. The investigation of polyphyllin D has emerged as a primary focus in this field, with lung cancer, breast cancer, and liver cancer being the key areas of current research. Lastly, polyphyllin saponins show potential application in the field of cancer.

Unveiling autophagy complexity in leukemia: The molecular landscape and possible interactions with apoptosis and ferroptosis

Autophagy is a self-digestion multistep process in which causes the homeostasis through degradation of macromolecules and damaged organelles. The autophagy-mediated tumor progression regulation has been a critical point in recent years, revealing the function of this process in reduction or acceleration of carcinogenesis. Leukemia is a haematological malignancy in which abnormal expansion of hematopoietic cells occurs. The current and conventional therapies from chemotherapy to cell transplantation have failed to appropriately treat the leukemia patients. Among the mechanisms dysregulated in leukemia, autophagy is a prominent one in which can regulate the hallmarks of this tumor. The protective autophagy inhibits apoptosis and ferroptosis in leukemia, while toxic autophagy accelerates cell death. The proliferation and invasion of tumor cells are tightly regulated by the autophagy. The direction of regulation depends on the function of autophagy that is protective or lethal. The protective autophagy accelerates chemoresistance and radio-resistsance. The non-coding RNAs, histone transferases and other pathways such as PI3K/Akt/mTOR are among the regulators of autophagy in leukemia progression. The pharmacological intervention for the inhibition or induction of autophagy by the compounds including sesamine, tanshinone IIA and other synthetic compounds can chance progression of leukemia.

Pentacyclic triterpene-amino acid derivatives induced apoptosis and autophagy in tumor cells, affected the JNK and PI3K/AKT/mTOR pathway

A series of pentacyclic triterpene-amino acid derivatives were synthesized and tested for anti-proliferative activity. The results showed that most of the target compounds had good anti-proliferative activity. 2c did not contain protecting groups and hydrochloride, had excellent cytotoxicity, so it had been selected for further study in the mechanism of action in T24 cells. The data from transcriptome sequencing indicated that 2c was found to be closely related to apoptosis and autophagy. Observation of fluorescence staining and analysis from flow cytometry demonstrated that 2c induced apoptosis and cause cell cycle arrest in S/G2 phase in T24 cells. Molecular mechanism studies exhibited that 2c induced apoptosis in the intrinsic and extrinsic pathways. 2c also induced cellular autophagy in T24 cells. Results from Western Blotting showed that 2c could activate JNK pathway and inhibit PI3K/AKT/mTOR pathway. In conclusion, 2c was deserved further investigation in the field of anti-tumor.

Polyphyllin I suppressed the apoptosis of intervertebral disc nucleus pulposus cells induced by IL-1β by miR-503-5p/Bcl-2 axis

BACKGROUND

There are no studies that have shown the role and underlying mechanism of Polyphyllin I (PPI)-mediated anti-apoptosis activity in nucleus pulposus cells (NPCs). The research aimed to evaluate the effects of PPI in interleukin (IL)-1β-induced NPCs apoptosis in vitro.

METHODS

Cell Counting Kit-8 (CCK-8) assay was used to detect cell viability, and cell apoptosis was evaluated by double-stained flow cytometry (FITC Annexin V/PI). The expression of miR-503-5p was quantified by real-time quantitative PCR (qRT-PCR), and the expression of Bcl-2, Bax, and cleaved caspase-3 was quantified by Western blot. Dual-luciferase reporter gene assay was used to detect the targeting relationship between miR-503-5p and Bcl-2.

RESULTS

PPI at 40 μg·mL^-1 markedly promoted the viability of NPCs (P < 0.01). Also, PPI inhibited apoptosis and reduction in proliferative activity induced by IL-1β in the NPCs (P < 0.001, 0.01). PPI treatment significantly inhibited the expression of apoptosis-related protein Bax, cleaved caspase-3 (P < 0.05, 0.01), and enhanced the level of anti-apoptotic protein Bcl-2 (P < 0.01). The proliferative activity of NPCs was significantly decreased and the apoptosis rate of NPCs was increased under IL-1β treatment (P < 0.01, 0.001). Moreover, miR-503-5p was highly expressed in IL-1β-induced NPCs (P < 0.001). Furthermore, the effect of PPI on NPCs viability and apoptosis in IL-1β treatment was dramatically reversed by the overexpression of miR-503-5p (P < 0.01, 0.01). The targeted binding of miR-503-5p to the 3'UTR of Bcl-2 mRNA was confirmed by dual-luciferase reporter gene assays (P < 0.05). In further experiments, compared with miR-503-5p mimics, the effects of PPI on IL-1β-induced NPCs viability and apoptosis were greatly reversed by the co-overexpression of miR-503-5p and Bcl-2 (P < 0.05, 0.05).

CONCLUSION

PPI suppressed the apoptosis of intervertebral disk (IVD) NPCs induced by IL-1β via miR-503-5p/Bcl-2 molecular axis.

Cytotoxic steroidal glycosides from the rhizomes of Paris polyphylla var. yunnanensis

Paris polyphylla var. yunnanensis (Franch.) Hand.-Mazz. (Melanthiaceae), an important specie of the genus Paris, has long been in a traditional Chinese medicine (TCM) for a long time. This study aimed to isolate and identify the structures of bioactive saponins from the rhizomes of P. polyphylla var. yunnanensis and evaluate their cytotoxicity against BxPC-3, HepG2, U373 and SGC-7901 carcinoma cell lines. Seven previously undescribed and seven known saponins were identified, and Paris saponins VII (PSVII) showed significant cytotoxicity against the BxPC-3 cell line with IC₅₀ values of 3.59 μM. Furthermore, flow cytometry, transmission electron microscopy and western-bolt analysis revealed that PSVII inhibited the proliferation of BxPC-3 cells and might be involved in inducing apoptosis and pyroptosis by activating caspase-3, -7 and caspase-1, respectively.

GSK3 inhibitor suppresses cell growth and metabolic process in FLT3-ITD leukemia cells

Glycogen Synthase Kinase-3 (GSK-3) was recently implicated in the dysregulated biology of acute myeloid leukemia (AML). Low concentrations of GSK-3 inhibitors, SB216763 and BIO, suppressed the proliferation of AML cells with FLT3-ITD as early as 24 h after treatment. BIO was used in subsequent assays since it exhibited higher inhibitory effects than SB216763. BIO-induced G1 cell cycle arrest by regulating the expression of cyclin D2 and p21 in MV4-11 cells, and promoted apoptosis by regulating the cleaved-caspase3 signaling pathways. In vivo assays demonstrated that BIO suppressed tumor growth, while metabolomics assay showed that BIO reduced the levels of ATP and pyruvate in MV4-11 cells suggesting that it inhibited glycolysis. BIO markedly suppressed cell growth and induced apoptosis of AML cells with FLT3-ITD by partially inhibiting glycolysis, suggesting that BIO may be a promising therapeutic candidate for AML.

Network pharmacology-based investigation and experimental validation of the mechanism of scutellarin in the treatment of acute myeloid leukemia

Background: It has been demonstrated that scutellarin, a natural flavone compound from Scutellaria lateriflora and Scutellaria barbata, exerts selective cytotoxicity against a range of cancer cells. However, the underlining mechanism of scutellarin on acute myeloid leukemia (AML) remains elusive.

Methods: In this study, the combination of network pharmacology and experimental verification was performed to identify the pharmacological mechanisms of scutellarin for AML therapy. The public databases, such as PharmMapper, UniProt, OMIM, GeneCards, DrugBank and PharmGkb database, were used to sceen the potential targets of scutellarin and AML. The protein-protein interaction (PPI), gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were conducted to uncover the mechanism of scutellarin in the treatment of AML. Finally, the network pharmacological results were further confirmed by in vitro and in vivo experiments.

Results: First and foremost, we totally obtained 289 target genes for scutellarin and 10998 disease targets for AML. 253 overlapping genes were preliminarily considered the potential targets of scutellarin for AML treatment. The results of PPI network analysis, GO analysis and KEGG pathway enrichment demonstrated that the anti-AML effect of scutellarin may focused on MAPK signaling pathway. Furthermore, the cytologic tests suggested that scutellarin can inhibit AML cells proliferation through the mediation of JNK/Caspase-3 pathway. Meanwhile, pretreatment with the JNK inhibitor SP600125 rescued scutellarin-induced apoptosis. Similarly, scutellarin obviously suppressed subcutaneous xenograft growth in nude mice via regulating the JNK/Caspase-3 signaling pathway.

Conclusion: In this study, we integrated network pharmacology-based prediction and experimental validation and revealed the importance of the JNK pathway in scutellarin-mediated AML treatment.

Polyphyllin I Promotes Autophagic Cell Death and Apoptosis of Colon Cancer Cells via the ROS-Inhibited AKT/mTOR Pathway

Colon cancer is a common malignant tumor of the digestive tract, and it is considered among the biggest killers. Scientific and reasonable treatments can effectively improve the survival rate of patients if performed in the early stages. Polyphyllin I (PPI), a pennogenyl saponin isolated from Paris polyphylla var. yunnanensis, has exhibited strong anti-cancer activities in previous studies. Here, we report that PPI exhibits a cytotoxic effect on colon cancer cells. PPI suppressed cell viability and induced autophagic cell death in SW480 cells after 12 and 24 h, with the IC50 values 4.9 ± 0.1 μmol/L and 3.5 ± 0.2 μmol/L, respectively. Furthermore, we found PPI induced time-concentration-dependent autophagy and apoptosis in SW480 cells. In addition, down-regulated AKT/mTOR activity was found in PPI-treated SW480 cells. Increased levels of ROS might link to autophagy and apoptosis because reducing the level of ROS by antioxidant N-acetylcysteine (NAC) treatment mitigated PPI-induced autophagy and apoptosis. Although we did not know the molecular mechanism of how PPI induced ROS production, this is the first study to show that PPI induces ROS production and down-regulates the AKT/mTOR pathway, which subsequently promotes the autophagic cell death and apoptosis of colon cancer cells. This present study reports PPI as a potential therapeutic agent for colon cancer and reveals its underlying mechanisms of action.

Developments in the Antitumor Activity, Mechanisms of Action, Structural Modifications, and Structure-Activity Relationships of Steroidal Saponins

Steroidal saponins, a class of natural products formed by the combination of spirosteranes with sugars, are widely distributed in plants and have various biological activities, such as anti-tumor, anti-inflammatory, anti-bacterial, anti-Alzheimer's, anti-oxidation, etc. Particularly, extensive researches on the antitumor property of steroidal saponins have been received. Steroidal sapogenins, the aglycones of steroidal saponins, also have attracted much attention due to a vast range of pharmacological activities similar to steroidal saponins. In the past few years, structural modifications on the aglycones and sugar chains of steroidal saponins have been carried out and some achievements have been made. In this mini-review, the antitumor activity, action mechanisms, and structural modifications along with the structure-activity relationships of steroidal saponins and their derivatives are summarized.

Fisetin inhibits the proliferation, migration and invasion of pancreatic cancer by targeting PI3K/AKT/mTOR signaling

Pancreatic cancer is an extremely malignant digestive tract tumor. With the increase of chemotherapeutic resistance of pancreatic cancer, clinical treatment is in a dilemma. Hence, it is pivotal to design an effective drug for treating individuals with pancreatic cancer. Fisetin extracted from vegetables, as well as fruits was explored to possess antioxidant, anti-cancer, anti-inflammatory along with anti-microbial properties. Nonetheless, there is limited research focusing on the utility of fisetin as an inhibitor of pancreatic cancer. Similarly, the mechanism through which Fisetin dampens pancreatic cancer remains unknown. This research work systematically evaluated the possible anti-cancer influences of fisetin in pancreatic cancer, as well as explored its responsible molecular mechanism. Our data revealed that fisetin obviously dampens pancreatic cancer progress in vitro along with in vivo dose-dependently. Furthermore, we established that fisetin repressed pancreatic cancer via explicitly targeting PI3K/AKT/mTOR signaling cascade and not the JAK2 cascade. Our data clarified that fisetin is a prospective anti-cancer drug for pancreatic cancer, as well as indicated the distinct molecular target of fisetin.

Network Pharmacology and Experimental Validation Reveal the Effects of Chidamide Combined With Aspirin on Acute Myeloid Leukemia-Myelodysplastic Syndrome Cells Through PI3K/AKT Pathway

Chidamide (CDM), a novel histone deacetylase inhibitor, is currently used for patients with peripheral T-cell lymphoma. Aspirin (ASA), an anti-inflammatory drug, has been shown to exert anticancer activity. Herein, we investigated the effect of CDM combined with ASA on myelodysplastic syndromes-derived acute myeloid leukemia (AML-MDS) cells and explored the underlying mechanism. The putative targets of CDM and ASA were predicted by network pharmacology approach. GO functional and KEGG pathway enrichment analyses were performed by DAVID. Furthermore, experimental validation was conducted by Cell Counting Kit-8 assay, Flow cytometry and Western blotting. Network pharmacology analysis revealed 36 AML-MDS-related overlapping genes that were targets of CDM and ASA, while 10 hub genes were identified by the plug-in cytoHubba in Cytoscape. Pathway enrichment analysis indicated CDM and ASA significantly affected PI3K/AKT signaling pathway. Functional experiments demonstrated that the combination of CDM and ASA had a remarkable synergistic anti-proliferative effect by blocking the cell cycle in G0/G1 phase and inducing apoptosis. Mechanistically, the combination treatment significantly down-regulated the phosphorylation levels of PI3K and AKT. In addition, insulin-like growth factor 1 (IGF-1), an activator of PI3K/AKT pathway, reversed the effects of the combination treatment. Our findings suggested that CDM combined with ASA exerted a synergetic inhibitory effect on cell growth by inactivating PI3K/AKT pathway, which might pave the way for effective treatments of AML-MDS.

NMR-based Metabolomic Techniques Identify the Anticancer Effects of Three Polyphyllins in HepG2 Cells

Background:

Rhizoma Paridis (RP) is a traditional Chinese herb used for the treatment of tumors, detoxification and hemostasia. Studies show the main components of RP are Polyphyllin I (PPI), polyphyllin VI (PPVI), and polyphyllin VII (PPVII). However, the pharmaco-mechanisms of these compounds are not clear.

Objective:

By used 1 H nuclear magnetic resonance (1 H-NMR) based metabolomics approach to identify the Anticancer effects of PPI, PPVI and PPVII in HepG2 cells. Methods 1 H nuclear magnetic resonance (1 H-NMR) based metabolomics approach was applied to investigate the toxicological effect of PPI, PPVI, PPVII on HepG2 cells. Multivariate statistical analysis was employed to examine the metabolic changes and abnormal metabolic pathways, including Principal Component Analysis (PCA), Partial Least Squares Discriminant Analysis (PLS-DA), and orthogonal PLS-DA (OPLS-DA).

Results:

The results showed that the effects of metabolic phenotypes were affected separately by PPI, PPVI, and PPVII. The metabolic phenotypes were also changed over time. The characteristic metabolites were varied by affecting different polyphylins, which were identified by the reconstructed OPLSDA loading plots. According to the characteristic metabolites, the mainly disturbed metabolic pathways were found, such as alanine, aspartate and glutamate metabolism, pyruvate metabolism, glycine, serine, and threonine metabolism.

Conclusion:

The current work could allow us to understand the therapeutic effect of RP in metabolism. It also indicated that RP would be a promising candidate for liver cancer treatment.

Chaihu Guizhi Ganjiang Decoction Ameliorates Pancreatic Fibrosis via JNK/mTOR Signaling Pathway

Pancreatic fibrosis is a pathological characteristic of chronic pancreatitis (CP) and pancreatic cancer. Chaihu Guizhi Ganjiang Decoction (CGGD) is a traditional Chinese medicine, which is widely used in the clinical treatment of digestive diseases. However, the potential anti-fibrosis mechanism of CGGD in treating CP remains unclear. Here, we conducted a series of experiments to examine the effect of CGGD on the CP rat model and primary isolated pancreatic stellate cells (PSCs). The results revealed that CGGD attenuated pancreatic damage, decreased collagen deposition, and inhibited PSC activation in the pancreas of CP rats. However, compared with the CP group, CGGD had no effect on body weight and serum amylase and lipase. In addition, CGGD suppressed autophagy by downregulating Atg5, Beclin-1, and LC3B and facilitated phosphorylation of mTOR and JNK in pancreatic tissues and PSCs. Moreover, the CGGD-containing serum also decreased LC3B or collagen I expression after rapamycin (mTOR inhibitor) or SP600125 (JNK inhibitor) treatment in PSCs. In conclusion, CGGD attenuated pancreatic fibrosis and PSC activation, possibly by suppressing autophagy of PSCs through the JNK/mTOR signaling pathway.

JNK signaling as a target for anticancer therapy

The JNKs are members of mitogen-activated protein kinases (MAPK) which regulate many physiological processes including inflammatory responses, macrophages, cell proliferation, differentiation, survival, and death. It is increasingly clear that the continuous activation of JNKs has a role in cancer development and progression. Therefore, JNKs represent attractive oncogenic targets for cancer therapy using small molecule kinase inhibitors. Studies showed that the two major JNK proteins JNK1 and JNK2 have opposite functions in different types of cancers, which need more specification in the design of JNK inhibitors. Some of ATP- competitive and ATP non-competitive inhibitors have been developed and widely used in vitro, but this type of inhibitors lack selectivity and inhibits phosphorylation of all JNK substrates and may lead to cellular toxicity. In this review, we summarized and discussed the strategies of JNK binding inhibitors and the role of JNK signaling in the pathogenesis of different solid and hematological malignancies.

Comparison of the Effects of Nonprotein and Protein Nitrogen on Apoptosis and Autophagy of Rumen Epithelial Cells in Goats

Protein nutrition is particularly important for the self-renewal processes of gastrointestinal epithelial cells. The self-renewal of cells is inseparable from the interaction between apoptosis and autophagy. However, there are few reports on the relationship between different nitrogen sources and apoptosis/autophagy. In this study, the relative protein expression of Bcl-2-associated X protein(Bax), caspase-3, and p62 was significantly higher (p < 0.05), while that of Bcl-xl, Bcl-2, Beclin1, and Microtuble-associated protein light chain 3 (LC3-II) was significantly lower (p < 0.05), in the NH4Cl group in comparison with the NH4Cl + 4-phenylbutyric acid (4PBA) group. In addition, the relative protein expression of Bax and caspase-3 was significantly higher (p < 0.05), while that of Bcl-2 and Bcl-xl was decreased significantly (p < 0.05), in the NH4Cl + 3-Methyladenine (3-MA) group and the methionine (Met) + 3-MA group in comparison with the NH4Cl group. Furthermore, the relative protein expression of Beclin1 and LC3B-II was significantly lower (p < 0.05), while that of p62 was significantly higher (p < 0.05), in the NH4Cl + Z-VAD-FMK group and the Met + Z-VAD-FMK group in comparison with the NH4Cl group. In conclusion, our results suggested that endoplasmic reticulum (ER) stress played a critical role in the crosstalk between apoptosis and autophagy induced by NH4Cl and Met. Autophagy had a more obvious ameliorative effect on ruminal epithelial cell apoptosis after treatment with nonprotein nitrogen than after treatment with protein nitrogen. These findings may reveal the molecular mechanism of apoptosis and autophagy induced by nonprotein nitrogen and protein nitrogen.

Polyphyllin I Promoted Melanoma Cells Autophagy and Apoptosis via PI3K/Akt/mTOR Signaling Pathway

To investigate whether Polyphyllin I (PPI) might induce the autophagy and apoptosis of melanoma cells by regulating PI3K/Akt/mTOR signal pathway. Melanoma A375 cells were incubated with different concentrations of Polyphyllin I (0, 1.5, 3.0, and 6.0 mg/L) and PI3K/Akt/mTOR signaling pathway activator IGF-1(20 mg/L). CCK-8 assay was utilized to detect cell proliferation; Cell apoptosis and cell cycle were measured by flow cytometry; Western blot was used to examine the expressions of proteins. Immunofluorescence analysis was performed to evaluate autophagy of A375 cells; In addition, xenograft-bearing nude mice were applied to study the role of Polyphyllin I on melanoma development, melanoma cell proliferation, as well as melanoma cell apoptosis in vivo. The outcomes represented that Polyphyllin I promoted A375 cell apoptosis via upregulating Bax level and cleaved caspase-3 level and downregulating Bcl-2 level, inhibited the growth of A375 cells at the G0/G1 phase, and enhanced cell autophagy via regulating the levels of Beclin 1, LC3II, and p62. However, IGF-1 (an activator of PI3K/Akt/mTOR signal pathway) attenuated these changes that Polyphyllin I induced. Furthermore, the xenograft model experiment confirmed that Polyphyllin I treatment suppressed xenograft tumor growth, increased apoptotic index evaluated by the TUNEL method, and reduced the level of Ki67 in tumor tissues in vivo. In conclusion, Polyphyllin I treatment enhanced melanoma cell autophagy and apoptosis, as well as blocked melanoma cell cycle via suppressing PI3K/Akt/mTOR signal pathway. Meanwhile, Polyphyllin I treatment suppressed the development of melanoma in vivo. Therefore, Polyphyllin I possibly is a promising molecular targeted agent used in melanoma therapy.

Chemopreventive effect of Betulinic acid via mTOR -Caspases/Bcl2/Bax apoptotic signaling in pancreatic cancer

Background

Pancreatic cancer is aggressive with no symptoms until the advanced stage reached. The increased resistance of pancreatic cancer to chemotherapy demonstrates a dilemma in the clinical field. Hence, it is a matter of great urgency to develop an effective drug to treat patients with pancreatic cancer. Betulinic acid is a major triterpene isolated from spina date seed. Several studies have suggested its low toxicity and side effects to patients with malaria and inflammation. However, relevant studies on betulinic acid in inhibiting cancer were insufficient and the molecular mechanism was unclear. This study aimed to systematically explore the potential anti-cancer functions of betulinic acid in pancreatic cancer, and investigate its underlying molecular mechanism.

Methods

The Counting Kit-8 assay, colony formation, transwell invasion assay, wound healing assay, flow cytometry and xenograft nude mice model were used to evaluate the effect of betulinic acid on the proliferation, invasion and migration ability of pancreatic cancer cells.

Results

Our results showed that betulinic acid obviously suppressed pancreatic cancer both in vitro and in vivo in a dose-dependent manner. We also determined that betulinic acid inhibited pancreatic cancer by specifically targeting mTOR signaling rather than Nrf2 or JAK2.

Conclusions

These findings clarify that betulinic acid is a potential and valuable anticancer agent for pancreatic cancer, and indicate the specific molecular target of betulinic acid.

Polyphyllin VI Induces Apoptosis and Autophagy via Reactive Oxygen Species Mediated JNK and P38 Activation in Glioma

Background

Polyphyllin VI (PPVI), a bioactive component derived from a traditional Chinese herb Paris polyphylla, exhibits potential antitumor activity against hepatocellular carcinoma, as well as breast and lung cancers. However, its effect on glioma remains unknown.

Methods

Five glioma cell lines (U251, U343, LN229, U87 and HEB) and an animal model were employed in the study. Anti-proliferation effects of PPVI were first determined using CCK-8 cell proliferation and clone formation assays, then reactive oxygen species (ROS), cell cycle progression and apoptosis effects measured by flow cytometry. The effect of PPVI on protein expression was quantified by Western blot analysis.

Results

Data showed that PPVI inhibited the proliferation of glioma cell lines by modulating the G2/M phase. Additionally, incubation of cells with PPVI promoted apoptosis, autophagy, increased accumulation of ROS and activated ROS-modulated JNK and p38 pathways. On the other hand, N-acetyl cysteine, a ROS inhibitor, attenuated PPVI-triggered effects. Furthermore, JNK and p38 inhibitors ameliorated PPVI-triggered autophagy and apoptosis in glioma cells. In vivo assays showed that PPVI inhibited tumor growth of U87 cell line in nude mice.

Conclusion

Overall, these data suggested that PPVI might be an effective therapeutic agent for glioma.

Polyphyllin I activates AMPK to suppress the growth of non-small-cell lung cancer via induction of autophagy

Polyphyllin I (PPI), a bioactive constituent extracted from the rhizomes of Paris polyphylla, is cytotoxic to several cancer types. This study was designed to explore whether PPI prevents non-small-cell lung cancer (NSCLC) growth and to investigate the molecular mechanism. AMP-activated protein kinase (AMPK) has been implicated in the activation of autophagy in distinct tissues. In cultured human NSCLC cell lines, PPI induces autophagy by activating AMPK and then inhibiting mTOR signaling in a concentration-dependent manner. Furthermore, the activation of autophagy induced by PPI was reversed by the AMPK inhibitor compound C. Computational docking showed that PPI directly interacted with the allosteric drug and metabolite site of AMPK to stabilize its activation. Microscale thermophoresis and Drug Affinity Responsive Targeting Stability (DARTS) assay further confirmed the high affinity between PPI and AMPK. In vivo studies indicated that PPI suppressed the growth of NSCLC and increased the levels of LC3-II and phosphorylated AMPK in tumors isolated from a xenograft model of NSCLC in mice. Moreover, PPI exhibited favorable pharmacokinetics in rats. In summary, PPI conclusively acts as a direct AMPK activator to induce cell autophagy which inhibits the growth of NSCLC cells. In the future, PPI therapy should be applied to treat patients with NSCLC.

MDM2 inhibition-mediated autophagy contributes to the pro-apoptotic effect of berberine in p53-null leukemic cells

AIMS

Berberine (BBR) is reported to induce apoptosis and inhibit migration of leukemic cells, but the underlying pharmacological mechanisms have not been fully revealed. This study aims to investigate the possible mechanisms from the perspective of autophagy.

MAIN METHODS

P-53-null leukemic cell lines Jurkat and U937 were used for the in vitro study. MDC staining was used for observation of autophagy in leukemic cells, and Western blot analysis was for determination of the expression levels of autophagy-associated proteins. Apoptosis of the leukemic cells was detected by flow cytometry. Cellular location of MDM2 was observed with immunofluorescence staining. Ubiquitination of MDM2 was assessed by immunoprecipitation. Male 6-8-week-old NOD/SCID mice were used for evaluating the effect of BBR on chemotherapy sensitivity in vivo.

KEY FINDINGS

BBR induced autophagy in p53-null leukemic cells, which was inhibited by autophagy inhibitors 3-methyladenine. 3-methyladenine also inhibited BBR-induced apoptosis in leukemic cells. In addition, BBR not only decreased MDM2 mRNA expression, but also enhanced MDM2 self-ubiquitination in leukemic cells. Forced overexpression of MDM2 reversed the effect of BBR on autophagy and apoptosis. Furthermore, BBR promoted doxorubicin-induced autophagy and cell death in the leukemic cells and overexpression of MDM2 suppressed these effects. In vivo, BBR combined with doxorubicin achieved better therapeutic effect than doxorubicin alone.

SIGNIFICANCE

MDM2 inhibits autophagy and apoptosis in leukemic cells in a p53-independent manner. BBR induces autophagy in p53-null leukemic cells through downregulating MDM2 expression at both transcriptional and post-transcriptional levels, which may contribute to the anti-cancer effect of BBR in leukemia.

Inhibiting lysine 353 oxidation of GRP78 by a hypochlorous probe targeting endoplasmic reticulum promotes autophagy in cancer cells

The level of hypochlorous acid (HOCl) in cancer cells is higher than that in non-cancer cells. HOCl is an essential signal for the regulation of cell fate and works mainly through the protein post-translational modifications in cancer cells. However, the mechanism of HOCl regulating autophagy has not been clarified. Here we reported that a HOCl probe named ZBM-H targeted endoplasmic reticulum and induced an intact autophagy flux in lung cancer cells. Furthermore, ZBM-H promoted the binding of GRP78 to AMPK and increased the phosphorylation of AMPK in a dose- and time-dependent manner. GRP78 knockdown inhibited ZBM-H-induced AMPK phosphorylation and ZBM-H-stimulated autophagy. In addition, mass spectrometry combined with point mutation experiments revealed that ZBM-H increased GRP78 activity by inhibiting HOCl-induced lysine 353 oxidation of GRP78. Following ZBM-H treatment in vitro and in vivo, cell growth was significantly inhibited while apoptosis was induced. Nevertheless, exogenous HOCl partially reversed ZBM-H-inhibited cell growth and ZBM-H-induced GRP78 activation. In brief, we found that an endoplasmic reticulum-targeted HOCl probe named ZBM-H, acting through attenuating HOCl-induced GRP78 oxidation, inhibited tumor cell survival by promoting autophagy and apoptosis. Overall, these data demonstrated a novel mechanism of hypochlorous acid regulating autophagy by promoting the oxidation modification of GRP78.