RESUMEN
BACKGROUND: The phosphoinositide 3-kinase/protein kinase-B/mechanistic target of rapamycin (PI3K/Akt/mTOR) signalling pathway is crucial for cell survival, differentiation, apoptosis and metabolism. Xihuang pills (XHP) are a traditional Chinese preparation with antitumour properties. They inhibit the growth of breast cancer, glioma, and other tumours by regulating the PI3K/Akt/mTOR signalling pathway. However, the effects and mechanisms of action of XHP in hepatocellular carcinoma (HCC) remain unclear. Regulation of the PI3K/Akt/mTOR signalling pathway effectively inhibits the progression of HCC. However, no study has focused on the XHP-associated PI3K/Akt/mTOR signalling pathway. Therefore, we hypothesized that XHP might play a role in inhibiting HCC through the PI3K/Akt/mTOR signalling pathway. AIM: To confirm the effect of XHP on HCC and the possible mechanisms involved. METHODS: The chemical constituents and active components of XHP were analysed using ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS). Cell-based experiments and in vivo xenograft tumour experiments were utilized to evaluate the effect of XHP on HCC tumorigenesis. First, SMMC-7721 cells were incubated with different concentrations of XHP (0, 0.3125, 0.625, 1.25, and 2.5 mg/mL) for 12 h, 24 h and 48 h. Cell viability was assessed using the CCK-8 assay, followed by an assessment of cell migration using a wound healing assay. Second, the effect of XHP on the apoptosis of SMMC-7721 cells was evaluated. SMMC-7721 cells were stained with fluorescein isothiocyanate and annexin V/propidium iodide. The number of apoptotic cells and cell cycle distribution were measured using flow cytometry. The cleaved protein and mRNA expression levels of caspase-3 and caspase-9 were detected using Western blotting and quantitative reverse-transcription polymerase chain reaction (RT-qPCR), respectively. Third, Western blotting and RT-qPCR were performed to confirm the effects of XHP on the protein and mRNA expression of components of the PI3K/Akt/mTOR signalling pathway. Finally, the effects of XHP on the tumorigenesis of subcutaneous hepatocellular tumours in nude mice were assessed. RESULTS: The following 12 compounds were identified in XHP using high-resolution mass spectrometry: Valine, 4-gingerol, myrrhone, ricinoleic acid, glycocholic acid, curzerenone, 11-keto-ß-boswellic acid, oleic acid, germacrone, 3-acetyl-9,11-dehydro-ß-boswellic acid, 5ß-androstane-3,17-dione, and 3-acetyl-11-keto-ß-boswellic acid. The cell viability assay results showed that treatment with 0.625 mg/mL XHP extract decreased HCC cell viability after 12 h, and the effects were dose- and time-dependent. The results of the cell scratch assay showed that the migration of HCC cells was significantly inhibited in a time-dependent manner by the administration of XHP extract (0.625 mg/mL). Moreover, XHP significantly inhibited cell migration and resulted in cell cycle arrest and apoptosis. Furthermore, XHP downregulated the PI3K/Akt/mTOR signalling pathway, which activated apoptosis executioner proteins (e.g., caspase-9 and caspase-3). The inhibitory effects of XHP on HCC cell growth were determined in vivo by analysing the tumour xenograft volumes and weights. CONCLUSION: XHP inhibited HCC cell growth and migration by stimulating apoptosis via the downregulation of the PI3K/Akt/mTOR signalling pathway, followed by the activation of caspase-9 and caspase-3. Our findings clarified that the antitumour effects of XHP on HCC cells are mediated by the PI3K/Akt/mTOR signalling pathway, revealing that XHP may be a potential complementary therapy for HCC.
RESUMEN
BACKGROUND: Hepatocellular carcinoma (HCC) is characterized by dysregulation of the immune microenvironment and the development of chemoresistance. Specifically, expression of the programmed cell death protein 1 (PD-1)/programmed cell death 1 ligand 1 (PD-L1) axis, an immune checkpoint, may lead to tumour immune escape, resulting in disease progression. The latest research shows that tumour immune escape may be caused by the upregulation of PD-L1 mediated by hypoxia-inducible factor-1 alpha (HIF-1α), and simultaneous inhibition of HIF-1α and PD-L1 has the potential to enhance the host's antitumour immunity. Moreover, inhibition of the PD-1/PD-L1 axis may mitigate tumour chemoresistance. Shuyu pills (SYPs) contain immunity-enhancing and antitumour components, making them a potential HCC treatment. AIM: To investigate the efficacy of SYPs for HCC treatment via simultaneous HIF-1α and PD-L1 inhibition and the mechanism involved. METHODS: A subcutaneous xenograft tumour model was first established in BALB/c nude mice by the subcutaneous injection of 1 × 107 SMMC-7721 cells. Male mice (male, 5 weeks old; n = 24) were then randomly divided into the following four groups (n = 6): Control (0.9% normal saline), SYP (200 mg/kg), SYP + cisplatin (DDP) (200 mg/kg + 5 mg/kg DDP weekly via intraperitoneal injection), and DDP (5 mg/kg cisplatin weekly via intraperitoneal injection). The dose of saline or SYPs for the indicated mouse groups was 0.2 mL/d via intragastric administration. The tumour volumes and body weights of the mice were measured every 2 d. The mice were euthanized by cervical dislocation after 14 d of continuous treatment, and the xenograft tissues were excised and weighed. Western blot assays were used to measure the protein expression of HIF-1α, PD-1, PD-L1, CD4+ T cells, and CD8+ T cells in HCC tumours from mice. Quantitative reverse transcription polymerase chain reaction was used for real-time quantitative detection of PD-1, PD-L1, and HIF-1α mRNA expression. An immunofluorescence assay was conducted to examine the expression of CD4+ T cells and CD8+ T cells. RESULTS: Compared to mice in the control group, those in the SYP and SYP + DDP groups exhibited reduced tumour volumes and tumour weights. Moreover, the protein and mRNA expression levels of the oncogene HIF-1α and that of the negative immunomodulatory factors PD-1 and PD-L1 were decreased in both the SYP and SYP + DDP groups, with the decrease effects being more prominent in the SYP + DDP group than in the SYP group (HIF-1α protein: Control vs SYP, P = 0.0129; control vs SYP + DDP, P = 0.0004; control vs DDP, P = 0.0152, SYP + DDP vs DDP, P = 0.0448; HIF-1α mRNA: control vs SYP, P = 0.0009; control vs SYP + DDP, P < 0.0001; control vs DDP, P = 0.0003, SYP vs SYP + DDP, P = 0.0192. PD-1 protein: Control vs SYP, P = 0.0099; control vs SYP + DDP, P < 0.0001, SPY vs SYP + DDP, P = 0.0009; SYP + DDP vs DDP, P < 0.0001; PD-1 mRNA: control vs SYP, P = 0.0002; control vs SYP + DDP, P < 0.0001; control vs DDP, P = 0.0003, SPY vs SYP + DDP, P = 0.0003; SYP + DDP vs DDP, P = 0.0002. PD-L1 protein: control vs SYP, P < 0.0001; control vs SYP + DDP, P < 0.0001; control vs DDP, P < 0.0001, SPY vs SYP + DDP, P = 0.0040; SYP + DDP vs DDP, P = 0.0010; PD-L1 mRNA: Control vs SYP, P < 0.0001; control vs SYP + DDP, P < 0.0001; control vs DDP, P < 0.0001, SPY vs SYP + DDP, P < 0.0001; SYP + DDP vs DDP, P = 0.0014). Additionally, the quantitative and protein expression levels of CD4+ T cells and CD8+ T cells were simultaneously upregulated in the SYP + DDP group, whereas only the expression of CD4+ T cells was upregulated in the SYP group. (CD4+ T cell quantitative: Control vs SYP + DDP, P < 0.0001, SYP vs SYP + DDP, P = 0.0005; SYP + DDP vs DDP, P = 0.0002. CD4+ T cell protein: Control vs SYP, P = 0.0033; Control vs SYP + DDP, P < 0.0001; Control vs DDP, P = 0.0021, SYP vs SYP + DDP, P = 0.0004; SYP + DDP vs DDP, P = 0.0006. Quantitative CD8+ T cells: Control vs SYP + DDP, P = 0.0013; SYP vs SYP + DDP, P = 0.0347; SYP + DDP vs DDP, P = 0.0043. CD8+ T cell protein: Control vs SYP + DDP, P < 0.0001; SYP vs SYP + DDP, P < 0.0001; SYP + DDP vs DDP, P < 0.0001). Finally, expression of HIF-1α was positively correlated with that of PD-1/PD-L1 and negatively correlated with the expression of CD4+ T cells and CD8+ T cells. CONCLUSION: SYPs inhibit immune escape and enhance chemosensitization in HCC via simultaneous inhibition of HIF-1α and PD-L1, thus inhibiting the growth of subcutaneous xenograft HCC tumours.