Polyphyllin I inhibits invasion and epithelial-mesenchymal transition via CIP2A/PP2A/ERK signaling in prostate cancer

Altering phosphorylation in cancer through PP2A modifiers

Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase integral to the regulation of many cellular processes. Due to the deregulation of PP2A in cancer, many of these processes are turned toward promoting tumor progression. Considerable research has been undertaken to discover molecules capable of modulating PP2A activity in cancer. Because PP2A is capable of immense substrate specificity across many cellular processes, the therapeutic targeting of PP2A in cancer can be completed through either enzyme inhibitors or activators. PP2A modulators likewise tend to be effective in drug-resistant cancers and work synergistically with other known cancer therapeutics. In this review, we will discuss the patterns of PP2A deregulation in cancer, and its known downstream signaling pathways important for cancer regulation, along with many activators and inhibitors of PP2A known to inhibit cancer progression.

Polyphyllin I attenuates the invasion and metastasis via downregulating GRP78 in drug-resistant hepatocellular carcinoma cells

Drug resistance to chemotherapy agents presents a major obstacle to the effective treatment of hepatocellular carcinoma (HCC), a common type of liver cancer. Increasing evidence indicates a link between drug resistance and the recurrence of HCC. Polyphyllin I (PPI), a promising pharmaceutical candidate, has shown potential therapeutic advantages in the treatment of sorafenib-resistant hepatocellular carcinoma (SR-HCC cells). In this study, we sought to investigate the mechanism underlying the inhibitory effect of PPI on the invasion and metastasis of SR-HCC cells. Our in vitro studies included scratch wound-healing migration assays and transwell assays to examine PPI's effect on HCC cell migration and invasion. Flow cytometry was employed to analyze the accumulation or efflux of chemotherapy drugs. The results of these experiments demonstrated that PPI increased the susceptibility of HCC to sorafenib while inhibiting SR-HCC cell growth, migration, and invasion. Molecular docking analysis revealed that PPI exhibited a higher binding affinity with GRP78. Western blot analysis and immunofluorescence experiments showed that PPI reduced the expression of GRP78, E-cadherin, N-cadherin, Vimentin, and ABCG2 in SR-HCC cells. Interference with and overproduction of GRP78 in vitro impacted the proliferation, migration, invasion, and metastasis of HCC cells. Further examination revealed that PPI hindered the expression of GRP78 protein, resulting in a suppressive effect on SR-HCC cell migration and invasion. Histological examination of tumor tissue substantiated that administering PPI via gavage to HepG2/S xenograft nude mice inhibited tumor growth and significantly reduced tumor size, as evidenced by xenograft experiments involving nude mice. Hematoxylin and eosin (HE) staining of tumor tissue specimens, along with immunohistochemistry (IHC), were conducted to evaluate the expression levels of Ki67, GRP78, N-cadherin, Vimentin, and ABCG2. The results indicated that PPI administration decreased the levels of proteins associated with metastasis and markers of drug resistance in tumor tissues, impeding tumor growth and spread. Overall, our findings demonstrated that PPI effectively suppressed the viability, proliferation, invasion, and metastasis of SR-HCC cells both in vitro and in vivo by modulating GRP78 activity. These findings provide new insights into the mechanism of PPI inhibition of SR-HCC cell invasion and metastasis, highlighting PPI as a potential treatment option for sorafenib-resistant HCC.

Human pancreatic cancer patients with Epithelial-to-Mesenchymal Transition and an aggressive phenotype show a disturbed balance in Protein Phosphatase Type 2A expression and functionality

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) has a low survival, its incidence is rising and little therapeutic improvements are expected in the near future. It has been observed that Epithelial-to-Mesenchymal transition (EMT) contributes (including in PDAC) to a more aggressive cancer phenotype. Additionally, largely unexplored, studies indicate a mechanistic interplay between Protein Phosphatase Type 2A (PP2A) enzymes and EMT that could offer treatment opportunities. The aim was to investigate the relation of a PP2A expression signature (encompassing all PP2A subunits, endogenous inhibitors and activators) with EMT and aggressive pancreatic cancer, and to discuss possible implications.

METHODS

We retrieved different PDAC expression datasets from NCBI to capture the variation in patients, and analyzed these using datamining, survival analysis, differential gene and protein expression. We determined genes highly associated with aggressive PDAC. For in vitro evaluation, Panc-1 cells were treated with the pharmacologic PP2A inhibitor Okadaic Acid (OA). Additionally, two OA-resistant Panc-1 clones were developed and characterized.

RESULTS

In patients, there is a strong correlation between EMT and aggressive PDAC, and between aggressive PDAC and PP2A, with a significant upregulation of PP2A inhibitor genes. Several PP2A genes significantly correlated with decreased survival. In vitro, short-term exposure to OA induced EMT in Panc-1 cells. This shift towards EMT was further pronounced in the OA-resistant Panc-1 clones, morphologically and by pathway analysis. Proteomic analysis and gene sequencing showed that the advanced OA-resistant model most resembles the clinical PDAC presentation (with EMT signature, and with several specific PP2A genes upregulated, and others downregulated).

CONCLUSIONS

We demonstrated a strong association between EMT, altered PP2A expression and aggressive PDAC in patients. Also, in vitro, PP2A inhibition induces EMT. Overall, statistics suggests the mechanistic importance of PP2A dysregulation for PDAC progression. Translationally, our observations indicate that pharmacologic restoration of PP2A activity could be an attractive therapeutic strategy to block or reverse progression.

Polyphyllin I suppresses the gastric cancer growth by promoting cancer cell ferroptosis

Background: Ferroptosis is a new form of regulated cell death characterized by the accumulation of iron-dependent lipid peroxides and membrane damages. Recent studies have identified an important role for cancer cell ferroptosis in antitumor therapy. On the other hand, polyphyllin I (PPI) has been reported to exert antitumor effects on some types of cancers. However, it remains unknown whether or not PPI regulates cancer cell ferroptosis.

Methods: Two types of human gastric cancer cells (AGS and MKN-45) were used to establish tumor xenograft models in nude mice that were treated with polyphyllin I (PPI) to observe tumor growth, while cells also were cultured for in vitro studies. Ferroptosis, based on the intracellular ROS/lipid ROS production and accumulation of ferrous ions, was detected using a fluorescence microscope and flow cytometer, while the expression of NRF2/FTH1 was measured using Western blotting assays.

Results: Here we found that PPI inhibited the gastric cancer growth in vivo and in vitro while increasing the intracellular reactive oxygen species (ROS)/lipid peroxides and ferrous ions in the gastric cancer cells. PPI also decreased the levels of nuclear factor erythroid 2-related factor 2 (NRF2) and ferritin heavy chain 1 (FTH1) in gastric cancer cells in vitro. Moreover, liproxstain-1, an inhibitor of cell ferroptosis, mostly reversed the cell ferroptosis and tumor growth arrest induced by PPI. Finally, the effects of PPI on cancer cell ferroptosis were diminished by the overexpression of NRF2.

Conclusion: For the first time, our results have demonstrated that PPI exerts its antitumor activity on the gastric cancer by, at least partially, inducing cancer cell ferroptosis via regulating NRF2/FTH1 pathway. These findings may be implicated for clinical replacement therapy of the gastric cancer.

From Basic Science to Clinical Practice: The Role of Cancerous Inhibitor of Protein Phosphatase 2A (CIP2A)/p90 in Cancer

Cancerous inhibitor of protein phosphatase 2A (CIP2A), initially reported as a tumor-associated antigen (known as p90), is highly expressed in most solid and hematological tumors. The interaction of CIP2A/p90, protein phosphatase 2A (PP2A), and c-Myc can hinder the function of PP2A toward c-Myc S62 induction, thus stabilizing c-Myc protein, which represents a potential role of CIP2A/p90 in tumorigeneses such as cell proliferation, invasion, and migration, as well as cancer drug resistance. The signaling pathways and regulation networks of CIP2A/p90 are complex and not yet fully understood. Many previous studies have also demonstrated that CIP2A/p90 can be used as a potential therapeutic cancer target. In addition, the autoantibody against CIP2A/p90 in sera may be used as a promising biomarker in the diagnosis of certain types of cancer. In this Review, we focus on recent advances relating to CIP2A/p90 and their implications for future research.

Therapeutic effects on cancer of the active ingredients in rhizoma paridis

Cancer is a major threat to human health, with high mortality and a low cure rate, continuously challenging public health worldwide. Extensive clinical application of traditional Chinese medicine (TCM) for patients with poor outcomes of radiotherapy and chemotherapy provides a new direction in anticancer therapy. Anticancer mechanisms of the active ingredients in TCM have also been extensively studied in the medical field. As a type of TCM against cancer, Rhizoma Paridis (Chinese name: Chonglou) has important antitumor effects in clinical application. The main active ingredients of Rhizoma Paridis (e.g., total saponins, polyphyllin I, polyphyllin II, polyphyllin VI, and polyphyllin VII) have shown strong antitumor activities in various cancers, such as breast cancer, lung cancer, colorectal cancer, hepatocellular carcinoma (HCC), and gastric cancer. Rhizoma Paridis also has low concentrations of certain other active ingredients with antitumor effects, such as saponins polyphyllin E, polyphyllin H, Paris polyphylla-22, gracillin, and formosanin-C. Many researchers have studied the anticancer mechanism of Rhizoma Paridis and its active ingredients. This review article describes research progress regarding the molecular mechanism and antitumor effects of the active ingredients in Rhizoma Paridis, suggesting that various active ingredients in Rhizoma Paridis may be potentially therapeutic against cancer.

Anticancer Effect of Polyphyllin I in Suppressing Stem Cell-Like Properties of Hepatocellular Carcinoma via the AKT/GSK-3β/β-Catenin Signaling Pathway

Polyphyllin I (PPI), also called Chong Lou saponin I, is a steroidal saponin isolated from the rhizome of Paris polyphylla. PPI has been demonstrated to have strong anticancer activity. However, its effect on the stemness of liver cancer stem cells (LCSCs) is not completely understood. Herein, we aimed to investigate the effect of PPI on the stem cell-like features of LCSCs and hepatocellular carcinoma (HCC). LCSCs were enriched in a serum-free medium and treated with PPI, sorafenib (Sora), or PPI and Sora. Several endpoints, including spheroid formation and differentiation, cell proliferation, surface markers of LCSCs, PPI binding targets, and stemness-associated protein expression, were evaluated. Immunofluorescence staining, quantitative real-time polymerase chain reaction, siRNA transfection, and coimmunoprecipitation ubiquitination assays were conducted for in-depth mechanistic studies. Evaluation of in vivo antitumor efficacy demonstrated that PPI effectively inhibited the proliferation of liver cancer cells and the self-renewal and differentiation of LCSCs. Flow cytometry indicated that PPI suppressed the expression of the stem cell surface markers EpCAM and CD13. Molecular docking showed a high affinity between PPI and proteins of the Wnt/β-catenin signaling pathway, including AKT, GSK-3β, and β-catenin, with the binding energies of -5.51, -5.32, and -5.40 kcal/mol, respectively, which suggested that PPI might regulate the Wnt/β-catenin signaling pathway to affect the stem cell-like properties of HCC. Further ex vivo experiments implied that PPI activated the AKT/GSK-3β-mediated ubiquitin proteasomal degradation of β-catenin and subsequently attenuated the prooncogenic effect of LCSCs. Finally, the anticancer property of PPI was confirmed in vivo. It was found that PPI inhibited the tumor growth in an HCC cell line xenograft model. Taken together, molecular docking analysis and experimental data highlighted the novel function of PPI in suppressing the stem cell-like characteristics of LCSCs via the AKT/GSK-3β/β-catenin signaling pathway.

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.

Polyphyllin I Inhibits Propionibacterium acnes-Induced IL-8 Secretion in HaCaT Cells by Downregulating the CD36/NOX1/ROS/NLRP3/IL-1β Pathway

Acne vulgaris (AV) is a chronic skin disease involving inflammation of the pilosebaceous units. Propionibacterium acnes (P. acnes) hypercolonization is one pathogenic factor for AV. P. acnes that triggers interleukin-1β (IL-1β) by activating the pyrin domain-containing 3 protein (NLRP3) inflammasome of the NOD-like receptor family in human monocytes. Reactive oxygen species (ROS) acts as a trigger for the production of IL-8 and activates theNLRP3 inflammasome. IL-8 promotes the metastasis and multiplication of different cancerous cells, whereas keratinocyte proliferation and migration contribute to the progression of AV. A steroidal saponin called polyphyllin I (PPI) that is extracted from Paris polyphylla's rhizomes has anti-inflammatory properties. This study investigates the regulatory role of P. acnes in the secretion of IL-8 mediated by the CD36/NADPH oxidase 1 (NOX1)/ROS/NLRP3/IL-1β pathway and the effects of PPI on the CD36/NOX1/ROS/NLRP3/IL-1β/IL-8 pathway and human keratinocyte proliferation and migration. HaCaT cells were cultured and stimulated with 10⁸ CFU/ml of P. acnes for 0, 6, 12, 18, 24, 30, and 36 hours. P. acnes induced IL-8 secretion from HaCaT cells via the CD36/NOX1/ROS/NLRP3/IL-1β pathway. PPI inhibited the CD36/NLRP3/NOX1/ROS/IL-8/IL-1β pathway and HaCaT cell proliferation and migration. PPI alleviates P. acnes-induced inflammatory responses and human keratinocyte proliferation and migration, implying a novel potential therapy for AV.

Exploring the effect of Polyphyllin I on hepatitis B virus-related liver cancer through network pharmacology and in vitro experiments

AIM AND OBJECTIVE

To investigate the effect of Polyphyllin I (PPI) on HBV-related liver cancer through network pharmacology and in vitro experiments, and to explore its mechanism of action.

MATERIALS AND METHODS

Use bioinformatics software to predict the active ingredient target of PPI and the disease target of liver cancer, and perform active ingredient-disease target analysis. The results of network pharmacology through molecular docking and in vitro experiments can be further verified. The HepG2 receptor cells (HepG2. 2. 15) were transfected with HBV plasmid for observation, with the human liver cancer HepG2 being used as the control.

RESULTS

Bioinformatics analysis found that PPI had totally 161 protein targets, and the predicted target and liver cancer targets were combined to obtain 13 intersection targets. The results of molecular docking demonstrated that PPI had good affinity with STAT3, PTP1B, IL2, and BCL2L1. The results of the in vitro experiments indicated that the PPI inhibited cell proliferation and metastasis in a concentration-dependent manner (P<0.01). Compared with the vehicle group, the PPI group of 1.5, 3, and 6 μmol/L can promote the apoptosis of liver cancer to different degrees (P<0.01).

CONCLUSION

The present study revealed the mechanism of PPI against liver cancer through network pharmacology and in vitro experiments. Its mechanism of action is related to the inhibition of PPI on the proliferation of HBV-related liver cancer through promoting the apoptosis of liver cancer cells. Additionally, in vitro experiments have also verified that PPI can promote the apoptosis of HepG2 and HepG2.2.15 cells.

Interaction Of c-Jun And HOTAIR- Increased Expression Of p21 Converge In Polyphyllin I-Inhibited Growth Of Human Lung Cancer Cells

Background

Lung cancer is a leading cause of cancer-related death worldwide. Previously we demonstrated that polyphyllin I (PPI), a bioactive component extracted from Paris polyphylla, inhibited the growth of non-small cell lung cancer (NSCLC) cells through the SAPK/JNK-mediated suppressing p65, DNMT1 and EZH2 expressions. However, the molecular mechanism underlying anti-lung cancer effect by PPI still remain elusive.

Purpose

In this current study, we further explored the molecular mechanism underlying the anti-lung cancer effect of PPI.

Methods

MTT, Cell-Light^TM EdU DNA cell proliferation and colony formation assays were used to measure cell growth. Western blot were used to examine protein levels of c-Jun and p21. The expression level of long non-codingth RNA HOX transcript antisense RNA (HOTAIR) was measured by qRT-PCR. The p21 promoter activity was measured by Dual-Luciferase Reporter Assay System. The transient transfection experiments were used to silence and overexpression of c-Jun, p21 and HOTAIR. Tumor xenograft and bioluminescent imaging experiments were carried out to confirm the in vitro findings.

Results

 We showed that PPI suppressed growth of NSCLC cells. Mechanistically, we observed that PPI reduced expression of HOTAIR, while increased transcription factor c-Jun protein levels. Additionally, PPI also induced protein expression and promoter activity of p21, a cyclin-dependent kinase inhibitor. While exogenously expressed HOTAIR showed no effect on c-Jun levels, silencing of c-Jun significantly reversed the PPI-inhibited HOTAIR expression. Moreover, excessive expressed c-Jun further enhanced PPI-inhibited HOTAIR expression and PPI-induced p21 protein levels. Intriguingly, overexpression of HOTAIR and silencing of c-Jun overcame the PPI-induced p21 protein and promoter activity. Finally, silencing of p21 neutralized the PPI-inhibited cell proliferation. Similar results were also found in one xenograft mouse model.

Conclusion

 Our results demonstrate that PPI inhibits growth of NSCLC cells through regulation of HOTAIR and c-Jun expressions, which lead to induction of p21 gene. The interactions among HOTAIR, c-Jun and p21 regulatory axis converge in the overall anti-lung cancer effect of PPI. This study unveils an additional new mechanism for the anti-lung cancer role of PPI.

Prognostic Significance of CIP2A in Esophagogastric Junction Adenocarcinoma: A Study of 65 Patients and a Meta-Analysis

Background

The expression of the cancerous inhibitor protein phosphatase 2A (CIP2A) appears to be predictive of the prognosis of various solid tumors. However, the association between this protein and the risk of esophagogastric junction adenocarcinoma (EGJA) remains unclear. We investigated CIP2A expression and its clinical significance in EGJA and conducted a meta-analysis to explore the relationship between CIP2A and the prognosis of patients with solid tumors.

Methods

Immunohistochemistry (IHC) was performed to detect the expression of CIP2A in EGJA. Kaplan-Meier estimation, Cox analysis, and ROC curves were performed to analyze the survival of patients and the prognostic factors. In the meta-analysis, we searched relevant publications in several widely used databases and used 15 studies (2348 patients).

Results

IHC demonstrated that CIP2A was elevated in EGJA and correlated with poor survival as an independent indicator. It could forecast the survival more precisely when combined with the grade, which is another independent prognosis marker of EGJA. Meta-analysis demonstrated that the associations between the expression of CIP2A and the prognosis were detected for overall survival (HR = 1.98, 95%CI = 1.69‐2.32), disease-specific survival (HR = 1.72, 95%CI = 1.50‐1.97), and time to tumor progression (pooled HR = 1.95, 95%CI = 1.56‐2.43).

Conclusion

High expression of CIP2A was a poor indicator of the prognosis of EGJA, and CIP2A may be a new biomarker for the diagnosis and treatment of EGJA. The meta-analysis suggested that CIP2A expression can be a predictive marker of overall survival, disease-specific survival, and time to tumor progression in patients with solid tumors.

Cucurbitacin B Induces the Lysosomal Degradation of EGFR and Suppresses the CIP2A/PP2A/Akt Signaling Axis in Gefitinib-Resistant Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) patients carrying an epidermal growth factor receptor (EGFR) mutation are initially sensitive to EGFR-tyrosine kinase inhibitors (TKIs) treatment, but soon develop an acquired resistance. The treatment effect of EGFR-TKIs-resistant NSCLC patients still faces challenges. Cucurbitacin B (CuB), a triterpene hydrocarbon compound isolated from plants of various families and genera, elicits anticancer effects in a variety of cancer types. However, whether CuB is a viable treatment option for gefitinib-resistant (GR) NSCLC remains unclear. Here, we investigated the anticancer effects and underlying mechanisms of CuB. We report that CuB inhibited the growth and invasion of GR NSCLC cells and induced apoptosis. The inhibitory effect of CuB occurred through its promotion of the lysosomal degradation of EGFR and the downregulation of the cancerous inhibitor of protein phosphatase 2A/protein phosphatase 2A/Akt (CIP2A/PP2A/Akt) signaling axis. CuB and cisplatin synergistically inhibited tumor growth. A xenograft tumor model indicated that CuB inhibited tumor growth in vivo. Immunohistochemistry results further demonstrated that CuB decreased EGFR and CIP2A levels in vivo. These findings suggested that CuB could suppress the growth and invasion of GR NSCLC cells by inducing the lysosomal degradation of EGFR and by downregulating the CIP2A/PP2A/Akt signaling axis. Thus, CuB may be a new drug candidate for the treatment of GR NSCLC.

Cucurbitacin B Inhibits the Hippo-YAP Signaling Pathway and Exerts Anticancer Activity in Colorectal Cancer Cells

BACKGROUND Colorectal carcinoma (CRC) is one of the most frequently diagnosed malignancies. Cucurbitacin B (CuB) is a natural compound isolated from herbs and shows anticancer activity in several cancers. MATERIAL AND METHODS Here, we analyzed the effects of different CuB concentrations on the proliferative and invasive behaviors of CRC cells using MTT, clonogenic assay, Transwell invasion, and wound healing assays. Flow cytometry was performed to measure the apoptotic effects of CuB on CRC cells. Western blot and real-time PCR were used to investigate the expression of apoptosis and Hippo-YAP signaling pathway proteins. RESULTS CuB inhibited the proliferation and invasion of CRC cells while promoting apoptosis. In addition, the Western blot and real-time PCR results indicated that CuB suppressed YAP expression and its downstream target genes Cyr 61 and c-Myc in CRC cells. To assess the underlying mechanism, we investigated the upstream regulating factor LATS1, and the results revealed that CuB upregulated LATS1 expression in CRC cells. CONCLUSIONS In conclusion, our findings uncovered a novel therapeutic mechanism of CuB and suggest that there is therapeutic potential and feasibility in developing novel YAP inhibitors for cancer treatment.