Nrf2 Down-Regulation by Camptothecin Favors Inhibiting Invasion, Metastasis and Angiogenesis in Hepatocellular Carcinoma

Camptothecin enhances the anti-tumor effect of low-dose apatinib combined with PD-1 inhibitor on hepatocellular carcinoma

Apatinib has been shown to apply to a variety of solid tumors, including advanced hepatocellular carcinoma. Preclinical and preliminary clinical results confirmed the synergistic antitumor effects of apatinib in combination with anti-programmed death-1 (PD-1) inhibitors. In this study, we investigated camptothecin (CPT) enhances the anti-tumor effect of low-dose apatinib combined with PD-1 inhibitor on hepatocellular carcinoma. CPT combined with a PD-1 inhibitor enhances the anti-tumor effects of low-dose apatinib in hepatocellular carcinoma which was evaluated in making use of the H22 mouse model (n = 32), which was divided into four groups. Immunohistochemical staining and western blotting were used to detect nuclear factor erythroid 2-related factor 2 (Nrf2) as well as sequestosome 1 (p62), vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor receptor 2 (VEGFR2), PD-1, and programmed cell death ligand 1 (PD-L1). The results showed that the average size of the tumor of the combination group (Group D) was significantly less than that of the apatinib + PD-1 inhibitor group (Group C). The expression levels of Nrf2, p62, VEGFA, VEGFR2, PD-1, and PD-L1 in the apatinib + PD-1 inhibitor group(Group C) were lower than those in the control group (Group A) (P < 0.05). The expression levels of these genes in the apatinib + PD-1 inhibitor group (Group C) were significantly lower in the combination group (Group D) (P < 0.05). There was no obvious difference in body weight and liver and kidney functions between the four groups of mice. In conclusion, CPT improves the anti-tumor effect of low-dose apatinib combined with PD-1 inhibitor on hepatocellular carcinoma.

Nrf2 signaling pathway: current status and potential therapeutic targetable role in human cancers

Cancer is a borderless global health challenge that continues to threaten human health. Studies have found that oxidative stress (OS) is often associated with the etiology of many diseases, especially the aging process and cancer. Involved in the OS reaction as a key transcription factor, Nrf2 is a pivotal regulator of cellular redox state and detoxification. Nrf2 can prevent oxidative damage by regulating gene expression with antioxidant response elements (ARE) to promote the antioxidant response process. OS is generated with an imbalance in the redox state and promotes the accumulation of mutations and genome instability, thus associated with the establishment and development of different cancers. Nrf2 activation regulates a plethora of processes inducing cellular proliferation, differentiation and death, and is strongly associated with OS-mediated cancer. What's more, Nrf2 activation is also involved in anti-inflammatory effects and metabolic disorders, neurodegenerative diseases, and multidrug resistance. Nrf2 is highly expressed in multiple human body parts of digestive system, respiratory system, reproductive system and nervous system. In oncology research, Nrf2 has emerged as a promising therapeutic target. Therefore, certain natural compounds and drugs can exert anti-cancer effects through the Nrf2 signaling pathway, and blocking the Nrf2 signaling pathway can reduce some types of tumor recurrence rates and increase sensitivity to chemotherapy. However, Nrf2's dual role and controversial impact in cancer are inevitable consideration factors when treating Nrf2 as a therapeutic target. In this review, we summarized the current state of biological characteristics of Nrf2 and its dual role and development mechanism in different tumor cells, discussed Keap1/Nrf2/ARE signaling pathway and its downstream genes, elaborated the expression of related signaling pathways such as AMPK/mTOR and NF-κB. Besides, the main mechanism of Nrf2 as a cancer therapeutic target and the therapeutic strategies using Nrf2 inhibitors or activators, as well as the possible positive and negative effects of Nrf2 activation were also reviewed. It can be concluded that Nrf2 is related to OS and serves as an important factor in cancer formation and development, thus provides a basis for targeted therapy in human cancers.

Camptothecin Sensitizes Hepatocellular Carcinoma Cells to Sorafenib- Induced Ferroptosis Via Suppression of Nrf2

Sorafenib is a potent inducer of ferroptosis used to manage hepatocellular carcinoma (HCC). The ferroptosis induced by sorafenib activates the p62-Keap1-Nrf2 pathway. Abnormal activation of Nrf2 reduces sorafenib's efficiency and ferroptosis action and induces sorafenib's resistance. Consequently, our study tried to study the effect of a novel combination of sorafenib and Camptothecin (CPT, Nrf2 inhibitor) to improve sorafenib's ferroptosis action and reduce sorafenib resistance in the treatment of HCC. We evaluated the efficacy of sorafenib and/or CPT using HepG2 and Huh7 cell lines. MTT assay evaluated the anti-proliferation effects. The combination index (CI) and dose reduction index (DRI) were calculated using Isobologram analysis. Malondialdehyde (MDA), total antioxidant capacity (TAC), iron concentration, glutathione peroxidase (GPX4), and glutathione reductase (GR) activity assays were used to determine the ferroptosis action of drugs. Western blot was used to investigate the expression of the implicated proteins. Bioinformatics tools were used to determine the correlation between these proteins. Finally, the HPLC technique is used to measure cellular drug uptake. Our results revealed a strong synergism between sorafenib and CPT. The synergetic combination significantly increases lipid peroxidation and iron concentration, decreases TAC, GPX4 and GR activity, and reduces the expression of both Nrf2 and SLC7A11. The downregulation of Nrf2 expression has a vital role in the reduction of resistance mediators to sorafenib against HCC cells like (p62, MT1G, and ABCG2) and improves the cellular uptake of sorafenib. The current study provided evidence that Nrf2 inhibition by CPT improves sorafenib's sensitivity and reduces sorafenib's resistance via the augmentation of sorafenib's ferroptosis action.

The Multi-Faceted Consequences of NRF2 Activation throughout Carcinogenesis

The oxidative balance of a cell is maintained by the Kelch-like ECH-associated protein 1 (KEAP1)/nuclear factor erythroid 2-related factor 2 (NRF2) pathway. This cytoprotective pathway detoxifies reactive oxygen species and xenobiotics. The role of the KEAP1/NRF2 pathway as pro-tumorigenic or anti-tumorigenic throughout stages of carcinogenesis (including initiation, promotion, progression, and metastasis) is complex. This mini review focuses on key studies describing how the KEAP1/NRF2 pathway affects cancer at different phases. The data compiled suggest that the roles of KEAP1/NRF2 in cancer are highly dependent on context; specifically, the model used (carcinogen-induced vs genetic), the tumor type, and the stage of cancer. Moreover, emerging data suggests that KEAP1/NRF2 is also important for regulating the tumor microenvironment and how its effects are amplified either by epigenetics or in response to co-occurring mutations. Further elucidation of the complexity of this pathway is needed in order to develop novel pharmacological tools and drugs to improve patient outcomes.

Plant-derived natural products and combination therapy in liver cancer

Liver cancer is one of the malignant cancers globally and seriously endangers human health because of its high morbidity and mortality. Plant-derived natural products have been evaluated as potential anticancer drugs due to low side effects and high anti-tumor efficacy. However, plant-derived natural products also have defects of poor solubility and cumbersome extraction process. In recent years, a growing numbers of plant derived natural products have been used in combination therapy of liver cancer with conventional chemotherapeutic agents, which has improved clinical efficacy through multiple mechanisms, including inhibition of tumor growth, induction of apoptosis, suppression of angiogenesis, enhancement of immunity, reversal of multiple drug resistance and reduction of side effects. The therapeutic effects and mechanisms of plant-derived natural products and combination therapy on liver cancer are reviewed to provide references for developing anti-liver-cancer strategies with high efficacy and low side effects.

Camptothecin improves sorafenib sensitivity by inhibiting Nrf2‑ARE pathway in hepatocellular carcinoma

Sorafenib is a targeted drug for hepatocellular carcinoma (HCC), however, its efficacy is limited. Nuclear factor erythroid 2‑related factor 2 (Nrf2) contributes to sorafenib resistance. The present study investigated camptothecin (CPT) as a Nrf2 inhibitor to sensitize HCC to sorafenib. The effect of CPT on sorafenib sensitivity in HCC was assessed in vivo using H22 mice model (n=32) and VX2 rabbit models (n=32), which were sorted into four treatment groups. The expression levels of Nrf2, its downstream genes, including heme oxygenases‑1 (HO‑1) and NAD(P)H quinone oxidoreductase 1 (NQO1), and the epithelial‑mesenchymal transition markers Snail and N‑cadherin in tumors were determined using immunohistochemical staining and western blotting. Magnetic resonance imaging was used to monitor changes in tumor microcirculation and activity before and after treatment. Mouse body weights, liver and kidney function were monitored to evaluate the safety of combined therapy. The results revealed that the mean tumor size of the combined group was significantly smaller than that of sorafenib group for both models. The expression levels of Nrf2, heme oxygenase‑1, NAD(P)H quinone oxidoreductase 1, Snail, and N‑cadherin in the sorafenib group were significantly higher than control group (P<0.05). However, the expression levels of these genes were decreased in the combined group (P<0.05). Microcirculation perfusion and tumor activity in the combined group were also lower than sorafenib group. There were no significant differences in mouse body weight or liver and kidney function among the four groups. In summary, CPT is a Nrf2 inhibitor that could enhance the efficacy of sorafenib against HCC.

Experimental study of camptothecin combined with drug-eluting bead transarterial chemoembolization in the rabbit VX2 liver tumor model

Drug-eluting bead transarterial chemoembolization (DEB-TACE) has been widely used in the treatment of liver cancer; however, the utilization rate of chemotherapeutic drugs after embolization is low. Chemotherapy resistance mediated by high nuclear factor E2-related factor 2 (NRF2) expression limits DEB-TACE efficacy. Camptothecin (CPT), an NRF2 inhibitor, exerts chemosensitizing effects. We designed a controlled experiment to determine the efficacy and feasibility of DEB-TACE combined with CPT for the treatment of rabbit VX2 hepatoma. DEB-TACE activated NRF2 expression in the tumor region. NRF2 activation could be inhibited by the combined use of CPT. After DEB-TACE alone, the tumor necrosis was incomplete, there were still highly active tumor residues, and the apparent diffusion coefficient (ADC) value, which was negatively correlated with tumor activity observed by magnetic resonance imaging, remained low. After DEB-TACE combined with CPT, the relative necrosis of the tumor was more complete, the ADC value was higher, and the ADC change was greater. The single application of CPT did not result in evident liver function and physical burden to the rabbits. The combined use of CPT and DEB-TACE did not significantly increase DEB-TACE imaging of liver function and body. In conclusion, CPT can also inhibit high NRF2 expression after DEB-TACE treatment. Combining CPT with DEB-TACE can improve the sensitivity of DEB-TACE in the treatment of VX2 tumors, improve the therapeutic effect, and has no evident toxic and side effects. This study explored the methods for enhancing the efficacy of DEB-TACE in liver cancer from a new perspective and performed model experiments, which provided a theoretical basis for future clinical treatment.

High expression of serine and arginine-rich splicing factor 9 (SRSF9) is associated with hepatocellular carcinoma progression and a poor prognosis

BACKGROUND

Serine and arginine-rich splicing factor 9 (SRSF9) has been linked to the occurrence and progression of various cancers; however, its effects and mechanism of action hepatocellular carcinoma (HCC) have not been reported. In this study, we used a bioinformatics approach and in vitro assays to evaluate the expression of SRSF9 in HCC, its prognostic value, and its underlying regulatory mechanisms, including analyses of related pathways and the role of methylation.

METHODS

Transcriptomic and DNA methylation data for 357 HCC cases and 50 paratumor tissues in The Cancer Genome Atlas database were obtained. Additionally, protein expression data for cell lines and tissue samples were obtained from the Human Protein Atlas. The CMap databased was used to predict candidate drugs targeting SRSF9. Various cell lines were used for in vitro validation.

RESULTS

SRSF9 expression was significantly elevated in HCC and was negatively regulated by its methylation site cg06116271. The low expression of SRSF9 and hypermethylation of cg06116271 were both associated with a longer overall survival time. A correlation analysis revealed ten genes that were co-expressed with SRSF9; levels of CDK4, RAN, DENR, RNF34, and ANAPC5 were positively correlated and levels of RBP4, APOC1, MASP2, HP, and HPX were negatively correlated with SRSF9 expression. The knockdown of SRSF9 in vitro inhibited the proliferation and migration of HCC cells and significantly reduced the expression of proteins in the Wnt signaling pathway (DVL2 and β-catenin) and cell cycle pathway (Cyclin D and Cyclin E). A CMap analysis identified two drugs, camptothecin and apigenin, able to target and inhibit the expression of SRSF9.

CONCLUSIONS

This study expands our understanding of the molecular biological functions of SRSF9 and cg06116271 and provides candidate diagnostic and therapeutic targets for HCC.

High-content screening of active components of Traditional Chinese Medicine inhibiting TGF-β-induced cell EMT

The epithelial mesenchymal transition (EMT) has roles in metastasis and invasion during fibrotic diseases and cancer progression. Some Traditional Chinese Medicines (TCMs) have shown inhibitory effects with respect to the EMT. The current study attempted to establish a multiparametric high-content method to screen for active monomeric compounds in TCM with the ability to target cellular EMT by assessing phenotypic changes. A total of 306 monomeric compounds from the MedChemExpress (MCE) compound library were screened by the high-content screening (HCS) system and 5 compounds with anti-EMT activity, including camptothecin (CPT), dimethyl curcumin (DMC), artesunate (ART), sinapine (SNP) and berberine (BER) were identified. To confirm anti-EMT activity, expression of EMT markers was assessed by qRT-PCR and Western blotting, and cell adhesion and migration measured by cell function assays. The results revealed that CPT, DMC, ART, SNP and BER inhibited transforming growth factor-β1 (TGF-β1)-induced expression of vimentin and α-SMA, upregulated expression of E-cadherin, increased cell adhesion and reduced cell migration. In summary, by quantifying the cell morphological changes during TGF-β1-induced EMT through multi-parametric analysis, TCM compounds with anti-EMT activity were successfully screened using the HCS system, a faster and more economical approach than conventional methods.

Galactosed and Reduction-Responsive Nanoparticles Assembled from Trimethylchitosan–Camptothecin Conjugates for Enhanced Hepatocellular Carcinoma Therapy

The targeted delivery of drugs to tumor cells and prevention of premature release before reaching the target is one of the key challenges to developing nanomedicines. In this paper, galactose decorated trimethyl chitosan (GT)–camptothecin (CPT) prodrug nanoparticles (GT-ss-CPT NPs) were prepared from GT-CPT conjugates linked by dithiodipropionic acid. The obtained GT-ss-CPT NPs were spherical with a particle size of 184.1 nm. GT-ss-CPT NPs displayed low drug release under physiological conditions, whereas efficient drug release was triggered by high GSH concentration. GT-ss-CPT NPs exhibited a higher antitumor effect both in vitro and in vivo than the free drug counterpart. More importantly, GT-ss-CPT NPs reduced the high systematic toxicity of CPT to tumor-bearing mice. In summary, GT-ss-CPT NPs can not only inhibit the premature release of CPT but also have a great potential for targeted hepatocellular carcinoma chemotherapy.