Marsdenia tenacissima extract induces G0/G1 cell cycle arrest in human esophageal carcinoma cells by inhibiting mitogen-activated protein kinase (MAPK) signaling pathway

Marsdenia tenacissima extract (MTE, trade name: Xiao-Ai-Ping injection) is an extract of a single Chinese plant medicine. It has been used for the treatment of cancer in China for decades, especially for esophageal cancer and other cancers in the digestive tract. In the present study, the potential mechanism for MTE's activity in esophageal cancer was explored. The effects of MTE on the proliferation of human esophageal cancer cells (KYSE150 and Eca-109) were investigated by the MTT assay, the BrdU (bromodeoxyuridine) incorporation immunofluorescence assay, and flow cytometric analysis. MTE inhibited cell proliferation through inducing G0/G1 cell cycle arrest in KYSE150 and Eca-109. Western blot analysis was employed to determine protein levels in the MTE treated cells. Compared with the control cells, the expression levels of the cell cycle regulatory proteins cyclin D1/D2/D3, cyclin E1, CDK2/4/6 (CDK: cyclin dependent kinase), and p-Rb were decreased significantly in the cells treated with MTE at 40 mg·mL(-1). In addition, MTE had an inhibitory effect on the MAPK (mitogen-activated protein kinase) signal transduction pathway, including ERK (extracellular signal-regulated kinase), JNK (c-Jun N-terminal kinase), and p38MAPK. Moreover, MTE showed little additional effects on the regulation of cyclin D1/D3, CDK4/6, and p-Rb when the ERK pathway was already inhibited by the specific ERK inhibitor U0126. In conclusion, these data suggest that MTE inhibits human esophageal cancer cell proliferation through regulation of cell cycle regulatory proteins and the MAPK signaling pathways, which is probably mediated by the inhibition of ERK activation.

Marsdenia tenacissima extract enhances gefitinib efficacy in non-small cell lung cancer xenografts

PURPOSE

The stem of Marsdenia tenacissima (Roxb.) Wight et Arn. has long been used as a medicine to treat cancer in China. Our previous in vitro results showed that Marsdenia tenacissima extract (MTE) overcomes gefitinib resistance in non-small cell lung cancer (NSCLC) cells. However, it is unknown whether MTE could enhance gefitinib efficacy in vivo. The present study was intended to investigate the in vivo anti-tumour activity of MTE combined with gefitinib.

METHODS

Human NSCLC H460 (K-ras mutation) or H1975 cells (EGFR T790M mutation) were subcutaneously inoculated into nude mice. Tumour volume and body weight were measured regularly. Resected tumours were weighed after the animals were sacrificed. Immunoblotting or immunohistochemistry was used to assess the cellular proliferation and apoptosis in xenograft tumour tissue. Expression of the EGFR downstream pathways and c-Met were measured with western blot analysis to explore possible mechanisms.

RESULTS

MTE (5, 10, 20 g/kg) dose-dependently reduced tumour growth and induced cell apoptosis. MTE suppressed EGFR related signals, and 20 g/kg was the most effective dose. Low-dose MTE (5 g/kg) significantly enhanced gefitinib efficacy in resistant H460 and H1975 xenografts. The combination inhibited tumour proliferation and induced cell apoptosis in both resistant NSCLC xenografts. Constitutive activation of the PI3K/Akt and MEK/ERK pathways is related to EGFR-TKI resistance. Accordingly, phosphorylation of PI3K/Akt/mTOR and ERK1/2 was suppressed after combination treatment. Simultaneously, cross-talked c-Met and EGFR were also prominently lowered in the presence of MTE combined with gefitinib.

CONCLUSION

The present results suggest that the combination of MTE and gefitinib may be a promising therapeutic approach to enhance gefitinib efficacy in resistant NSCLC.

Marsdenia tenacissima extract overcomes Axl- and Met-mediated erlotinib and gefitinib cross-resistance in non-small cell lung cancer cells

Tyrosine kinase inhibitors (TKIs) are an effective treatment strategy for non-small cell lung cancer (NSCLC) patients harboring mutations that result in constitutive activation of the epidermal growth factor receptor (EGFR). However, most patients eventually develop resistance to TKIs. This occurs due to additional EGFR mutations or the activation of bypass signaling pathways. In our previous work, we demonstrated that Marsdenia tenacissima extract (MTE) restored gefitinib sensitivity in resistant NSCLC cells with EGFR T790M or K-ras mutations. However, the potential efficacy of MTE in NSCLC cells with resistance mediated by Axl and c-Met, and the related molecular mechanisms need to be elucidated. In this study we evaluated the ability of MTE to restore erlotinib/gefitinib sensitivity in TKI resistant HCC827/ER cells and xenograft mice models. Our results demonstrate that MTE overcomes erlotinib and gefitinib resistance driven by Axl and c-Met in vitro and in vivo. Combination therapy significantly suppressed EGFR downstream molecules and the c-Met and Axl activated bypass signaling pathways. Moreover, we observed that MTE is more efficient at restoring resistance to erlotinib than gefitinib. As the Axl and c-Met mediated bypass pathways share the same downstream signaling cascade as EGFR, simultaneous targeting of these pathways is a promising strategy to overcome acquired resistance of TKIs. Our results demonstrate that MTE treatment attenuates Axl phosphorylation and the associated epithelial-mesenchymal transition, suggesting MTE treatment may be a potential therapeutic strategy for overcoming erlotinib and gefitinib cross-resistance in NSCLC, especially for erlotinib resistance.

Marsdenia tenacissima extract disturbs the interaction between tumor-associated macrophages and non-small cell lung cancer cells by targeting HDGF

ETHNOPHARMACOLOGICAL RELEVANCE

Marsdenia tenacissima (Roxb.) Wight et Arn. is a traditional Chinese herbal medicine, and its water-soluble ingredient Marsdenia tenacissima extract (MTE), was widely used for cancer treatment. The multi-pharmacological efficacies and mechanisms of MTE in directly inhibiting tumor cells have been extensively studied. However, the anti-tumor effects of MTE in the tumor-associated macrophages (TAMs) microenvironment remain unclear.

AIM OF THE STUDY

To uncover the role of hepatoma-derived growth factor (HDGF) in the interaction between TAMs and non-small cell lung cancer (NSCLC) cells. To evaluate the anti-tumor effects of MTE on the vicious crosstalk between TAMs and NSCLC by targeting HDGF.

MATERIALS AND METHODS

HDGF-overexpression PC-9 and H292 NSCLC cell lines were constructed and verified. RNA-sequencing (RNA-seq) was performed in HDGF-overexpression PC-9 cells to probe the differential expression of genes. THP-1-derived macrophages were characterized using specific markers after stimulation with phorbol-12-myristate 13-acetate (PMA) and rhIL-4 or rhHDGF. The role of HDGF both in NSCLC cells and TAMs was determined using approaches like Western blot, qRT-PCR, ELISA, and flow cytometry. The interaction between tumor cells and TAMs were assessed by indirect co-culture H1975, PC-9 cells with M2 type macrophages. The effects of MTE on anti-tumor and macrophage polarization were evaluated in vitro and in vivo.

RESULTS

RNA-seq results identified IL-4 as a critical response to HDGF in NSCLC. HDGF induced macrophages polarizing toward M2 type, and promoted NSCLC cells proliferation, migration and invasion in vitro. On the one hand, HDGF dose-dependently promoted IL-4 expression in NSCLC cells. On the other hand, HDGF induced M2 macrophage polarization through the IL-4/JAK1/STAT3 signaling pathway. MTE treatment significantly decreased the expression and secretion of HDGF in NSCLC cells. Meanwhile, MTE treatment led to M2 macrophage repolarization, as evidenced by decreased expression of M2 markers and increased levels of M1 markers. Importantly, MTE treatment significantly suppressed tumor development in C57BL/6 mice bearing Lewis lung cancer (LLC) cells in vivo, accompanied by decreased plasma HDGF levels, reduced M2 macrophages infiltration and increased M1 macrophages proportion in mice tumor tissues.

CONCLUSIONS

HDGF upregulated IL-4 expression in NSCLC cells, and promoted M2 polarization by the IL-4/JAK1/STAT3 signaling pathway in macrophages. MTE disturbed the interaction between NSCLC and TAMs in vitro, and inhibited tumor growth in vivo, at least in part, by suppressing HDGF. Therefore, our present study revealed a novel anti-tumor mechanism of MTE through inhibiting HDGF expression and enhancing macrophage polarization from M2 to M1 phenotype.

Marsdenia tenacissima extract induces endoplasmic reticulum stress-associated immunogenic cell death in non-small cell lung cancer cells through targeting AXL

ETHNOPHARMACOLOGICAL RELEVANCE

Marsdenia Tenacissima (Roxb.) Wight et Arn. is a traditional Chinese medicine. Its standardized extract (MTE), with the trade name Xiao-Ai-Ping injection, is widely used for cancer treatment. The pharmacological effects of MTE-inducing cancer cell death have been primarily explored. However, whether MTE triggers tumor endoplasmic reticulum stress (ERS)-associated immunogenic cell death (ICD) is unknown.

AIM OF THE STUDY

To determine the potential role of endoplasmic reticulum stress in the anti-cancer effects of MTE, and uncover the possible mechanisms of endoplasmic reticulum stress-associated immunogenic cell death induced by MTE.

MATERIAL AND METHODS

The anti-tumor effects of MTE on non-small cell lung cancer (NSCLC) were examined through CCK-8 and wound healing assay. Network pharmacology analysis and RNA-sequencing (RNA seq) were performed to confirm the biological changes of NSCLCs after MTE treatment. Western blot, qRT-PCR, reactive oxygen species (ROS) assay, and mitochondrial membrane potential (MMP) assay were used to explore the occurrence of endoplasmic reticulum stress. Immunogenic cell death-related markers were tested by ELISA and ATP release assay. Salubrinal was used to inhibit the endoplasmic reticulum stress response. SiRNA and bemcentinib (R428) were used to impede the function of AXL. AXL phosphorylation was regained by recombinant human Gas6 protein (rhGas6). The effects of MTE on endoplasmic reticulum stress and immunogenic cell death response were also proved in vivo. The AXL inhibiting compound in MTE was explored by molecular docking and confirmed by Western blot.

RESULTS

MTE inhibited cell viability and migration of PC-9 and H1975 cells. Enrichment analysis identified that differential genes after MTE treatment were significantly enriched in endoplasmic reticulum stress-related biological processes. MTE decreased mitochondrial membrane potential (MMP) and increased ROS production. Meanwhile, endoplasmic reticulum stress-related proteins (ATF6, GRP-78, ATF4, XBP1s, and CHOP) and immunogenic cell death-related markers (ATP, HMGB1) were upregulated, and the AXL phosphorylation level was suppressed after MTE treatment. However, when salubrinal (an endoplasmic reticulum stress inhibitor) and MTE were co-treated cells, the inhibitory effects of MTE on PC-9 and H1975 cells were impaired. Importantly, inhibition of AXL expression or activity also promotes the expression of endoplasmic reticulum stress and immunogenic cell death-related markers. Mechanistically, MTE induced endoplasmic reticulum stress and immunogenic cell death by suppressing AXL activity, and these effects were attenuated when AXL activity recovered. Moreover, MTE significantly increased the expression of endoplasmic reticulum stress-related markers in LLC tumor-bearing mouse tumor tissues and plasma levels of ATP and HMGB1. Molecular docking illustrated that kaempferol has the strongest binding energy with AXL and suppresses AXL phosphorylation.

CONCLUSION

MTE induces endoplasmic reticulum stress-associated immunogenic cell death in NSCLC cells. The anti-tumor effects of MTE are dependent upon endoplasmic reticulum stress. MTE triggers endoplasmic reticulum stress-associated immunogenic cell death by inhibiting AXL activity. Kaempferol is an active component that inhibits AXL activity in MTE. The present research revealed the role of AXL in regulating endoplasmic reticulum stress and enriched the anti-tumor mechanisms of MTE. Moreover, kaempferol may be considered a novel AXL inhibitor.

Marsdenia tenacissima extract prevents the malignant progression of glioma through upregulating lncRNA MEG3 and SFRP1-dependent inhibition of Wnt/β-catenin pathway

BACKGROUND/AIM

Recent studies have highlighted the tumor-suppressive effect of Marsdenia tenacissima extract (MTE) on human cancers. This research unveils the potential impact of MTE on glioma and ascertains the relevant molecular mechanisms.

METHODS

Glioma cells were treated with MTE, with normal human astrocytes (NHAs) as controls. A battery of function experiments, including the CCK-8 viability test, colony formation assay, scratch migration assay, and Transwell invasion assay, was executed to address the responses of glioma cells to MTE treatment and gain or loss of function of lncMEG3, miR-542-3p, and SFRP1. FISH, RIP, and dual-luciferase reporter assays were adopted for assessing gene interactions. U251-GFP-Luc cells were delivered into nude mice through intracranial injection to develop an orthotopic glioma model for in vivo validation.

RESULTS

200 mg/mL MTE could suppress the proliferating, migrating, and invading properties of glioma cells but not affect those of NHAs. MTE treatment enhanced the expression of lncMEG3, which competes with SFRP1 for binding miR-542-3p. SFRP1 could inactivate the Wnt/β-catenin pathway. Animal experimentation substantiated the antitumor activity and mechanism of MTE in nude mice.

CONCLUSIONS

MTE suppresses glioma via the lncMEG3/miR-542-3p/SFRP1/Wnt/β-catenin axis. These findings contribute to a theoretical basis for the use of MTE for glioma patients.