Paris saponin VII inhibits metastasis by modulating matrix metalloproteinases in colorectal cancer cells

Formosanin C inhibits triple-negative breast cancer progression by suppressing the phosphorylation of STAT3 and the polarization of M2 macrophages

INTRODUCTION

Triple-negative breast cancer (TNBC), is a highly aggressive tumor. Formosanin C (FC) is a diosgenin with immunomodulatory and antitumor properties, the precise mechanism through which it is against TNBC remains uncertain.

OBJECTIVE

Clarifying the mechanism of FC against TNBC.

MATERIALS AND METHODS

The impact of FC on two TNBC cell lines for 24 h was investigated through various techniques including the CCK8 assay, flow cytometry, transwell assay, scratch tests, immunoblot assay, and immunofluorescence. To elucidate the mechanism behind the anti-TNBC effect of FC, MDA-MB-231 cells were subjected to STAT3 overexpression. Moreover, the in vivo efficacy of FC was examined using a xenograft nude mice (BALB/C). Mice were divided into the control group (equal amount of PBS), the napabucasin group (5 mg/kg) and the FC groups (1 mg/kg, 2 mg/kg). The study duration was 30 days.

RESULTS

FC exhibited inhibitory effects against MDA-MB-231 and Hs578T cells. FC can decrease the migratory capacity of TNBC cells by inhibiting epithelial-mesenchymal transition (EMT). Meanwhile, we demonstrated that the inhibition of phosphorylation of STAT3 (Y705) is the crucial mechanism of FC against TNBC. Moreover, FC also hindered the polarization of macrophage M2.

DISCUSSION AND CONCLUSION

This study is the first to show that FC restrains the EMT of TNBC cells by obstructing the STAT3 pathway and hinders the M2 polarization of macrophages and immune evasion. Therefore, FC holds the possibility of being utilized as a therapeutic remedy for TNBC.

Study on the Effect of Quinoa Saponins on Human Colon Cancer HT-29 Cells

Quinoa saponins can inhibit the survival of specific cancer cells. However, there is still a lack of systematic research on the effects of quinoa saponins on colon cancer cells. This experiment confirmed that quinoa saponins prevented human colon cancer HT-29 cells from growing in vitro. The MTT experiment revealed that quinoa saponins significantly decreased the proliferative vitality of HT-29 cells. In comparison to the control group, the proportion of cell number in the G0/G1 phase increased by 22.97% and the rate of apoptosis increased by 22.55% after treating cells with quinoa saponins (40 μg/mL). By regulating the expression of Cyclin D1 and p21, it caused the cell cycle to be blocked in the G0/G1 phase. It also promoted the expression of Caspase3 and Bax while suppressing the expression of Bcl-2, which led to the apoptosis of HT-29 cells. In addition, quinoa saponins caused cells to undergo autophagy by upregulating the expression of LC-3II and Beclin1, while the addition of autophagy inhibitors significantly reduced the inhibitory effect on cell proliferation. Finally, the migration of HT-29 cells was also inhibited by quinoa saponins. After treating cells with quinoa saponins (40 μg/mL), compared with that in the control group, the wound healing rate of cells decreased by 38.21% and the migration ability decreased by 69.48%. The potential mechanism could be connected to increasing E-cadherin expression while decreasing N-cadherin expression. Importantly, all of these changes induced by quinoa saponins were dose dependent. Overall, these findings give a scientific basis for the anticancer mechanism of quinoa saponins.

Cellular and molecular mechanisms of gastrointestinal cancer liver metastases and drug resistance

Distant metastases and drug resistance account for poor survival of patients with gastrointestinal (GI) malignancies such as gastric cancer, pancreatic cancer, and colorectal cancer. GI cancers most commonly metastasize to the liver, which provides a unique immunosuppressive tumour microenvironment to support the development of a premetastatic niche for tumor cell colonization and metastatic outgrowth. Metastatic tumors often exhibit greater resistance to drugs than primary tumors, posing extra challenges in treatment. The liver metastases and drug resistance of GI cancers are regulated by complex, intertwined, and tumor-dependent cellular and molecular mechanisms that influence tumor cell behavior (e.g. epithelial-to-mesenchymal transition, or EMT), tumor microenvironment (TME) (e.g. the extracellular matrix, cancer-associated fibroblasts, and tumor-infiltrating immune cells), tumor cell-TME interactions (e.g. through cytokines and exosomes), liver microenvironment (e.g. hepatic stellate cells and macrophages), and the route and mechanism of tumor cell dissemination (e.g. circulating tumor cells). This review provides an overview of recent advances in the research on cellular and molecular mechanisms that regulate liver metastases and drug resistance of GI cancers. We also discuss recent advances in the development of mechanism-based therapy for these GI cancers. Targeting these cellular and molecular mechanisms, either alone or in combination, may potentially provide novel approaches to treat metastatic GI malignancies.

Advances in antitumor activity and mechanism of natural steroidal saponins: A review of advances, challenges, and future prospects

BACKGROUND

Cancer, the second leading cause of death worldwide following cardiovascular diseases, presents a formidable challenge in clinical settings due to the extensive toxic side effects associated with primary chemotherapy drugs employed for cancer treatment. Furthermore, the emergence of drug resistance against specific chemotherapeutic agents has further complicated the situation. Consequently, there exists an urgent imperative to investigate novel anticancer drugs. Steroidal saponins, a class of natural compounds, have demonstrated notable antitumor efficacy. Nonetheless, their translation into clinical applications has remained unrealized thus far. In light of this, we conducted a comprehensive systematic review elucidating the antitumor activity, underlying mechanisms, and inherent limitations of steroidal saponins. Additionally, we propose a series of strategic approaches and recommendations to augment the antitumor potential of steroidal saponin compounds, thereby offering prospective insights for their eventual clinical implementation.

PURPOSE

This review summarizes steroidal saponins' antitumor activity, mechanisms, and limitations.

METHODS

The data included in this review are sourced from authoritative databases such as PubMed, Web of Science, ScienceDirect, and others.

RESULTS

A comprehensive summary of over 40 steroidal saponin compounds with proven antitumor activity, including their applicable tumor types and structural characteristics, has been compiled. These steroidal saponins can be primarily classified into five categories: spirostanol, isospirostanol, furostanol, steroidal alkaloids, and cholestanol. The isospirostanol and cholestanol saponins are found to have more potent antitumor activity. The primary antitumor mechanisms of these saponins include tumor cell apoptosis, autophagy induction, inhibition of tumor migration, overcoming drug resistance, and cell cycle arrest. However, steroidal saponins have limitations, such as higher cytotoxicity and lower bioavailability. Furthermore, strategies to address these drawbacks have been proposed.

CONCLUSION

In summary, isospirostanol and cholestanol steroidal saponins demonstrate notable antitumor activity and different structural categories of steroidal saponins exhibit variations in their antitumor signaling pathways. However, the clinical application of steroidal saponins in cancer treatment still faces limitations, and further research and development are necessary to advance their potential in tumor therapy.

Polyphyllin VII protects from breast cancer-induced osteolysis by suppressing osteoclastogenesis via c-Fos/NFATc1 signaling

Bone is a preferred metastatic site of advanced breast cancer and the 5-year overall survival rate of breast cancer patients with bone metastasis is only 22.8%. Targeted inhibition of osteoclasts can treat skeletal-related events (SREs) in breast cancer patients. Polyphyllin VII (PP7), a pennogenyl saponin isolated from traditional Chinese herb Paris polyphylla, exhibits strong anti-inflammatory and anti-cancer activities. In this study, we evaluated the effect of PP7 on metastatic breast cancer-induced bone destruction in vivo and the underlying mechanisms. We found that intraperitoneal injection of 1 mg/kg PP7 significantly ameliorated the breast cancer MDA-MB-231 cell-induced osteolysis in mice. Mechanistically, PP7 (0.125-0.5 μM) inhibited the conditioned medium of MDA-MB-231 cells (MDA-MB-231 CM)-induced osteoclast formation in bone marrow-derived macrophages (BMMs). Furthermore, PP7 markedly reduced MDA-MB-231 CM-induced osteoclastic bone resorption and F-actin rings formation in vitro. During MDA-MB-231 CM-induced osteoclastogenesis, the activation of c-Fos and NFATc1 signaling was significantly downregulated by PP7, and finally osteoclast-related genes such as Oscar, Atp6v0d2, Mmp9 and β3 integrin were decreased. In addition, the formation of osteoblast was promoted by PP7 treatment. Our current findings revealed PP7 as a potential safe agent for preventing and treating bone destruction in breast cancer patients with bone metastases.

Hypoxia enhances the cytotoxic effect of As4S4 on rat ventricular H9c2 cells through activation of ubiquitin-proteasome system

BACKGROUND

As₄S₄ is widely used in Chinese traditional medicine compound. However, based on some recent studies, we found that the cardiotoxicity risk of using As₄S₄ in ischemic heart disease patients may be increased. To study this potential risk, we compared the effects of As₄S₄ on rat ventricular H9c2 cell line with or without hypoxic pretreatment, and to elucidate mechanisms of c-Cbl mediated ubiquitination/degradation of integrin β1.

METHODS

The present study was conducted on rat ventricular H9c2 cell line in the absence or presence of hypoxic pretreatment for 6 h followed by As₄S₄ treatment for 24 h. Following As₄S₄ treatment, cell viability assay, flow cytometric quantification of apoptotic cells, caspase-3 activity assay and DAPI staining were conducted. Western blotting was carried out to detect expressions of ubiquitination related proteins. In addition, the ubiquitination/degradation of integrin β1 and the role of c-Cbl in it was evaluated by immunoprecipitation and immunoblot assay.

RESULTS

The viability of cells with hypoxic pretreatment followed by As₄S₄ treatment was decreased significantly, apoptosis rate and the activity of caspase-3 were increased than As₄S₄ treatment alone. The ubiquitin-proteasome degradation pathway induced by As₄S₄ was further enhanced by hypoxic pretreatment. The results of IP and immunoblot assay showed hypoxic enhanced down-regulation effect of As₄S₄ on integrin β1 probably through c-Cbl activation.

CONCLUSIONS

This study demonstrated that the hypoxia enhanced cytotoxicity of As₄S₄ on H9c2 cells may through increasing the ubiquitin-proteasome degradation of integrin β1 mediated by the E3 ligase c-Cbl. The results provide an important clue that, in patients with ischemic heart disease, use of As₄S₄ may be associated with increased cardiotoxicity. We believe that the results worth to be further illuminated by in vivo and clinical research.

Biopharmaceutics classification evaluation for paris saponin VII

To study the biopharmaceutics characteristics of paris saponin VII (PSVII). The solubility of PSVII was evaluated by measurement of the equilibrium solubility in different solvents and media. The permeability of PSVII was evaluated by measuring the oil/water partition coefficient (lgP_app) and determining the apparent permeability coefficient (PC_app) on a mono-layer Caco-2 cell model. The effects of p-glycoprotein and multidrug resistance related protein 2 on PSVII transport in mono-layer Caco-2 cell model were further investigated. Finally, the small intestinal absorption of PSVII was investigated in rat. In solvents of different pH, the equilibrium solubility of PSVII was quite low, and the dose number of PSVII was larger than 1. The lgP_app of PSVII was less than 0. The apparent permeability coefficient [PC_app(AP-BL)] of PSVII in mono-layer Caco-2 cell model was less than 14.96 × 10^-6 cm·s^-1, and the efflux ratio of PSVII in mono-layer Caco-2 cell model was less than 1. The transport rate of PSVII in mono-layer Caco-2 cell model was not affected by the inhibitors of p-glycoprotein and multidrug resistance related protein 2. After oral administration, PSVII could be detected in rat intestinal contents, but could not be detected in the small intestinal mucosa. PSVII showed low solubility and permeability, which would result in low oral bioavailability in clinic. PSVII belonged to Class IV compound in biopharmaceutics classification system.

Preclinical Drug Discovery in Colorectal Cancer: A Focus on Natural Compounds

BACKGROUND

Colorectal cancer (CRC) is considered one of the most predominant and deadly cancer globally. Nowadays, the main clinical management for this cancer includes chemotherapy and surgery; however, these treatments result in the occurrence of drug resistance and severe side effects, and thus it is a crucial requirement to discover an alternative and potential therapy for CRC treatment. Numerous therapeutic cancers were initially recognized from natural metabolites utilized in traditional medicine, and several recent types of research have shown that many natural products own potential effects against CRC and may assist the action of chemotherapy for the treatment of CRC. It has been indicated that most patients are well tolerated by natural compounds without showing any toxicity signs even at high doses. Conventional chemotherapeutics interaction with natural medicinal compounds presents a new feature in cancer exploration and treatment. Most of the natural compounds overwhelm malignant cell propagation by apoptosis initiation of CRC cells and arresting of the cell cycle (especially at G, S, and G2/M phase) that result in inhibition of tumor growth.

OBJECTIVE

This mini-review aimed to focus on natural compounds (alkaloids, flavonoids, polysaccharides, polyphenols, terpenoids, lactones, quinones, etc.) that were identified to have anti- CRC activity in vitro on CRC cell lines and/or in vivo experiments on animal models.

CONCLUSION

Most of the studied active natural compounds possess anti-CRC activity via different mechanisms and pathways in vitro and in vivo that might be used as assistance by clinicians to support chemotherapy therapeutic strategy and treatment doses for cancer patients.

Polyphyllin II inhibits liver cancer cell proliferation, migration and invasion through downregulated cofilin activity and the AKT/NF-κB pathway

The morbidity and mortality of primary liver cancer is one of the highest amongst all cancers. Deficiency of effective treatment and characteristics of cancer metastasis are believed to be responsible for this situation, thus a great demand is required for new agent development. Polyphyllin II (PP2), an important steroidal saponin extracted from Rhizoma Paris, has emerged as a potential anti-cancer agent, but the effects of PP2 in liver cancers and its underlying mechanisms remain unexplored. In our study, we found that PP2 could remarkably suppress the proliferation of two liver cancer cell lines, HepG2 and BEL7402, resulting in significant cell death. Besides, low doses of PP2 have displayed properties that inhibit cellular motility and invasion of liver cancer cells. In addition, we have found that PP2-mediated cofilin activity suppression was implicated in the inhibition of liver cancer cell motility. Decreased expression of two major hydrolytic enzymes (MMP2/MMP9), through the AKT/NF-κB signaling pathway may also be also responsible for this process. Rescue experiments done with either non-phosphorylatable mutant cofilin-1 (S3A) transfection or an activator of the AKT pathway significantly reversed the inhibition effects of PP2 on liver cancer cells. Taken together, we report a potential agent for liver cancer treatment and reveal its underlying mechanisms.

Polyphyllin VII Promotes Apoptosis and Autophagic Cell Death via ROS-Inhibited AKT Activity, and Sensitizes Glioma Cells to Temozolomide

The high recurrence frequency of gliomas but deficiency of effective treatment and prevalent chemoresistance have elicited interests in exploring and developing new agents. Paris polyphyllins are monomers extracted from rhizome of Paris polyphylla var. yunnanensis. Here, we first reported that polyphyllin VII (PP7) exhibited cytotoxic effect on glioma cells. PP7 significantly suppressed the viability and induced cell death of U87-MG and U251 cells after 24 h, with the IC50 values 4.24 ± 0.87 μM and 2.17 ± 0.14 μM, respectively. Both apoptotic and autophagic processes were involved in the cytotoxic effect of PP7, as PP7 activated the Bcl2/Bax pathway and the inhibition of autophagy partly rescued the toxicity of PP7 in glioma cells. In addition, an inhibition of AKT/mTORC1 activity was found after PP7 administration, and it seemed that the overproduction of reactive oxygen species (ROS) was responsible for this effect. Namely, the removal of ROS by NAC treatment mitigated PP7-induced cell death, autophagy, and its effect on the AKT/mTORC1 signaling. Additionally, a combination assay of PP7 with temozolomide (TMZ), the most used chemotherapy for glioma patients, was performed resulting in synergism, while PP7 reduced TMZ resistance through inhibition of MGMT expression. Thus, our study reports PP7 as a potential agent for glioma treatment and reveals its underlying mechanisms of action.

Bax/Tubulin/Epithelial-Mesenchymal Pathways Determine the Efficacy of Silybin Analog HM015k in Colorectal Cancer Cell Growth and Metastasis

The inhibition of apoptosis, disruption of cellular microtubule dynamics, and over-activation of the epithelial mesenchymal transition (EMT), are involved in the progression, metastasis, and resistance of colorectal cancer (CRC) to chemotherapy. Therefore, the design of a molecule that can target these pathways could be an effective strategy to reverse CRC progression and metastasis. In this study, twelve novel silybin derivatives, HM015a-HM015k (15a−15k) and compound 17, were screened for cytotoxicity in CRC cell lines. Compounds HM015j and HM015k (15k and 15j) significantly decreased cell proliferation, inhibited colony formation, and produced cell cycle arrest in CRC cells. Furthermore, 15k significantly induced the formation of reactive oxygen species and apoptosis. It induced the cleavage of the intrinsic apoptotic protein (Bax p21) to its more efficacious fragment, p18. Compound 15k also inhibited tubulin expression and disrupted its structure. Compound 15k significantly decreased metastatic LOVO cell migration and invasion. Furthermore, 15k reversed mesenchymal morphology in HCT116 and LOVO cells. Additionally, 15k significantly inhibited the expression of the mesenchymal marker N-cadherin and upregulated the expression of the epithelial marker, E-cadherin. Compound 15k inhibited the expression of key proteins known to induce EMT (i.e., DVL3, β-catenin, c-Myc) and upregulated the anti-metastatic protein, cyclin B1. Overall, in vitro, 15k significantly inhibited CRC progression and metastasis by inhibiting apoptosis, tubulin activity and the EMT pathways. Overall, these data suggest that compound 15k should be tested in vivo in a CRC animal model for further development.

Polyphyllin VII increases sensitivity to gefitinib by modulating the elevation of P21 in acquired gefitinib resistant non-small cell lung cancer

Blockade of EGFR with reversible EGFR tyrosine kinase inhibitors (TKIs) is considered the frontline strategy for advanced NSCLC with EGFR mutations. However, acquired resistance to EGFR-TKI has been observed, resulting in disease progression and limited clinical benefit. Polyphyllin VII is the main member of polyphyllin family, which has been demonstrated to show strong anticancer activity against carcinomas. The sensitizing effect and underlying mechanism of Polyphyllin VII against acquired EGFR-TKI resistant NSCLC are still unexplored. In the present study, we aim to examined the sensitizing effect of Polyphyllin VII to gefitinib by modulating P21 signaling pathway in gefitinib acquired resistant NSCLC in vitro and in vivo. Gefitinib sensitive PC-9 cells and gefitinib acquired resistant H1975 cells were used. Cell proliferation and Clonogenic assay, Cell cycle analysis, Western blotting analysis and xenograft treatment were carried out. Polyphyllin VII enhanced the anti-proliferative effects of gefitinib and gefitinib-induced G1 phase arrest by modulation of P21 signaling pathway in acquired gefitinib resistant cells in vitro and in vivo. Polyphyllin VII elevated sensitization of gefitinib acquired resistant NSCLC cells to gefitinib through G1 phase arrest and modulation of P21 signaling pathway. It provides a potential new strategy to overcome gefitinib acquired resistance for EGFR-TKI resistant NSCLC.

C19-Norditerpenoid Alkaloids from Aconitum szechenyianum and Their Effects on LPS-Activated NO Production

Three new C₁₉-norditerpenoid alkaloids (1–3), along with two known C₁₉-norditerpenoid alkaloids (4–5) have been isolated from Aconitum szechenyianum. Their structures were established by extensive spectroscopic techniques and chemical methods as szechenyianine A (1), szechenyianine B (2), szechenyianine C (3), N-deethyl-3-acetylaconitine (4), and N-deethyldeoxyaconitine (5). Additionally, compounds 1–5 were tested for the inhibition of NO production on LPS-activated RAW264.7 cells with IC₅₀ values of 36.62 ± 6.86, 3.30 ± 0.11, 7.46 ± 0.89, 8.09 ± 1.31, and 11.73 ± 1.94 μM, respectively, while the positive control drug dexamethasone showed inhibitory activity with IC₅₀ value of 8.32 ± 1.45 μM. The structure-activity relationship of aconitine alkaloids were discussed.

Paris saponin VII suppresses osteosarcoma cell migration and invasion by inhibiting MMP‑2/9 production via the p38 MAPK signaling pathway

Metastasis is the primary cause of mortality in osteosarcoma. Targeting metastasis is a major strategy in osteosarcoma treatment. As a traditional Chinese medicine, Trillium tschonoskii Maxim has been widely used in the therapy of various diseases, including cancer. However, currently there is no evidence regarding the anti‑metastasic effect of Paris saponin VII (PS VII), which is extracted from Trillium tschonoskii Maxim, on osteosarcoma cells and its underling mechanisms. The present study aimed to examine the effect of PS VII on the migration and invasion of osteosarcoma cells. Viability and proliferation of osteosarcoma cells were examined by MTT assay. Migration and invasion of osteosarcoma cells was then detected using scratch wound healing assays and Transwell assays, respectively. Additionally, the expression of matrix metalloproteinase (MMP)‑2 and ‑9 was determined at the mRNA and protein level following treatment with PS VII. Mitogen‑activated protein kinase (MAPK) expression was also detected by western blot analysis. Finally, an inhibitor of p38 MAPK was used to verify the effect of PS VII on the expression of MMP‑2 and ‑9, as well as the migration and invasion osteosarcoma cells. This demonstrated that the proliferation, migration and invasion of the osteosarcoma cells were suppressed following treatment with PS VII. PS VII downregulated the expression of MMP‑2 and ‑9 in a dose‑ and time‑dependent manner. PS VII also exerted its ability to downregulate the phosphorylation of p38 MAPKs. Furthermore, by using a p38 inhibitor, SB203580, the role of PS VII in MMP‑2 and ‑9 expression and osteosarcoma cell invasion was revealed. Taken together, these results demonstrated that PS VII suppresses the migration and invasion of osteosarcoma cells via the p38 MAPK signaling pathway.

Protective effect of Trillium tschonoskii saponin on CCl4-induced acute liver injury of rats through apoptosis inhibition

To explore hepatoprotective role and underlying mechanisms of Trillium tschonoskii Maxim (TTM), 36 rats were randomly divided into control, CCl₄-induced liver injury model, and biphenyl dimethyl dicarboxylate (DDB) and low-, moderate-, and high-dose TTM treatment groups. After CCl₄-induced model establishment, the rats from DDB and TTM groups were administrated with DDB at 0.2 g/kg per day and TTM at 0.1, 0.5, and 1.0 g/kg per day, while the rats from control and model groups were administrated with saline. After 5 days of treatments, all rats were sacrificed for determining serum ALT and AST levels and liver index, examining histopathological changes in liver through HE and TUNEL staining, and evaluating TNF-α and IL-6 mRNA expression by real-time PCR, and caspase-3, Bcl-2, and Bax expression by Western blot. Results indicated that CCl₄ could induce acute liver injury and abnormal liver function in rats with obvious hepatomegaly, increased liver index, high ALT and AST levels, up-regulated TNF-α and IL-6, and overexpressed Bax and caspase-3. However, DDB and TTM could execute protective role in CCl₄-induced liver injury in rats through reducing ALT and AST levels, rescuing hepatomegaly, down-regulating inflammatory factors and inhibiting hepatocyte apoptosis in a dose-dependent manner. Therefore, TTM has obvious protective role in CCl₄-induced liver injury of rats through inhibiting hepatocyte apoptosis.

Anticancer Effects of Paris Saponins by Apoptosis and PI3K/AKT Pathway in Gefitinib-Resistant Non-Small Cell Lung Cancer

Background

Paris saponins have been studied for their anticancer effects in various cancer types, but the mechanisms underlying the cytotoxic effects, especially in EGFR-TKI-resistant cells, are still unclear. We explored the potential mechanism of the antitumor effects of PSI, II, VI, VII in EGFR-TKI-resistant cells and attempted to develop PSI, II, VI, VII as a systemic treatment strategy for EGFR-TKI-resistant lung cancer.

Material/Methods

Growth inhibition was detected by MTT assay. The apoptosis assay was detected using annexin-V/PI and Hoechst staining. The level of PI3K, pAKT, Bax, Bcl-2, caspase-3, and caspase-9 protein expression were detected using Western blot analysis.

Results

The results revealed that PSI, II, VI, VII inhibited the proliferation of PC-9-ZD cells. Furthermore, PSI, II, VI, VII induced significant cell apoptosis. The levels of PI3K, pAKT, Bcl-2 protein decreased, while the Bax, caspase-3, and caspase-9 protein was increased by PSI, II, PSVI, PSVII treatment and resulted in increased sensitivity to gefitinib in PC-9-ZD cells.

Conclusions

The underlying mechanism of Paris saponins may be related to targeting the PI3K/AKT pathways to cause apoptosis. Our results suggest a therapeutic potential of Paris saponins in clinical settings for gefitinib-resistant NSCLC.