NADPH: Quinone oxidoreductase 1 (NQO1) mediated anti-cancer effects of plumbagin in endocrine resistant MCF7 breast cancer cells

Plumbagin Regulates Snail to Inhibit Hepatocellular Carcinoma Epithelial-Mesenchymal Transition in vivo and in vitro

Background/Aims

Plumbagin (PL) has been shown to effe ctively inhibit autophagy, suppressing invasion and migration of hepatocellular carcinoma (HCC) cells. However, the specific mechanism remains unclear. This study aimed to investigate the effect of PL on tumor growth factor (TGF)-β-induced epithelial-mesenchymal transition (EMT) in HCC.

Methods

Huh-7 cells were cultured, and in vivo models of EMT and HCC-associated lung metastasis were developed through tail vein and in situ injections of tumor cells. In vivo imaging and hematoxylin and eosin staining were used to evaluate HCC modeling and lung metastasis. After PL intervention, the expression levels of Snail, vimentin, E-cadherin, and N-cadherin in the liver were evaluated through immunohistochemistry and Western blot. An in vitro TGF-β-induced cell EMT model was used to detect Snail, vimentin, E-cadherin, and N-cadherin mRNA levels through a polymerase chain reaction. Their protein levels were detected by immunofluorescence staining and Western blot.

Results

In vivo experiments demonstrated that PL significantly reduced the expression of Snail, vimentin, and N-cadherin, while increasing the expression of E-cadherin at the protein levels, effectively inhibiting HCC and lung metastasis. In vitro experiments confirmed that PL up-regulated epithelial cell markers, down-regulated mesenchymal cell markers, and inhibited EMT levels in HCC cells.

Conclusion

PL inhibits Snail expression, up-regulates E-cadherin expression, and down-regulates N-cadherin and vimentin expression, preventing EMT in HCC cells and reducing lung metastasis.

NQO-1 activatable NIR photosensitizer for visualization and selective killing of breast cancer cells

The diagnosis and treatment of breast cancer is of immense importance in improving patient outcomes. The biological marker NAD(P)H:quinone oxidoreductase 1 was utilized to design BrCyS-Q, a near-infrared activatable photosensitizer for breast cancer. BrCyS-Q was successfully employed to diagnose breast cancer cells using fluorescence and photodynamic inhibition. The findings of this research may offer novel insights for the diagnosis and treatment of clinical breast cancer via photodynamic therapy.

NQO1 drives glioblastoma cell aggressiveness through EMT induction via the PI3K/Akt/mTOR/Snail pathway

Glioblastoma multiforme (GBM) is the most frequent and lethal cancer derived from the central nervous system, of which the mesenchymal (MES) subtype seriously influences the survival and prognosis of patients. NAD(P)H: quinone acceptor oxidoreductase 1 (NQO1) serves an important role in the carcinogenesis and progression of various types of cancer; however, the specific mechanism underlying the regulatory effects of NQO1 on GBM is unclear. Thus, the present study aimed to explore the role and mechanism of NQO1 in GBM progression. The results of bioinformatics analysis and immunohistochemistry showed that high expression of NQO1 was significantly related to the MES phenotype of GBM and shorter survival. In addition, MTT, colony formation, immunofluorescence and western blot analyses, and lung metastasis model experiments suggested that silencing NQO1 inhibited the proliferation and metastasis of GBM cells in vitro and in vivo. Furthermore, western blotting showed that the activity of the PI3K/Akt/mTOR signaling pathway was revealed to be inhibited by downregulation of NQO1 expression, whereas it was enhanced by overexpression of NQO1. Notably, co‑immunoprecipitation and ubiquitination experiments suggested that Snail was considered an important downstream target of NQO1 in GBM cells. Snail knockdown could eliminate the promoting effect of ectopic NQO1 on the proliferation and invasion of GBM cells, and reduce its effects on the activity of PI3K/Akt/mTOR signaling pathway. These results indicated that NQO1 could promote GBM aggressiveness by activating the PI3K/Akt/mTOR signaling pathway in a Snail‑dependent manner, and NQO1 and its relevant pathways may be considered novel targets for GBM therapy.

A New Quinone-Based Inhibitor of Mitochondrial Complex I in D-Conformation, Producing Invasion Reduction and Sensitization to Venetoclax in Breast Cancer Cells

Mitochondrial Complex I plays a crucial role in the proliferation, chemoresistance, and metastasis of breast cancer (BC) cells. This highlights it as an attractive target for anti-cancer drugs. Using submitochondrial particles, we identified FRV-1, an ortho-carbonyl quinone, which inhibits NADH:duroquinone activity in D-active conformation and reduces the 3ADP state respiration dependent on Complex I, causing mitochondrial depolarization, ATP drop, increased superoxide levels, and metabolic remodeling towards glycolysis in BC cells. Introducing methyl groups at FRV-1 structure produced analogs that acted as electron acceptors at the Complex I level or increased the inhibitory effect of FCCP-stimulated oxygen consumption rate, which correlated with their redox potential, but increased toxicity on RMF-621 human breast fibroblasts was observed. FRV-1 was inactive in the naphthoquinone oxidoreductase 1 (NOQ1)-positive BC cell line, MCF7, but the sensitivity was recovered by dicoumarol, a NOQ1 inhibitor, suggesting that FRV-1 is a NOQ1 substrate. Importantly, FRV-1 selectively inhibited the proliferation, migration, and invasion of NQO1 negative BC cell, MDA-MB-231, in an OXPHOS- and ROS-dependent manner and sensitized it to the BH3 mimetic drug venetoclax. Overall, FRV-1 is a novel Complex I inhibitor in D-active conformation, blocking possibly the re-activation to A-state, producing selective anti-cancer effects in NQO1-negative BC cell lines.

Efforts in Bioprospecting Research: A Survey of Novel Anticancer Phytochemicals Reported in the Last Decade

Bioprospecting natural products to find prominent agents for medical application is an area of scientific endeavor that has produced many clinically used bioactive compounds, including anticancer agents. These compounds come from plants, microorganisms, and marine life. They are so-called secondary metabolites that are important for a species to survive in the hostile environment of its respective ecosystem. The kingdom of Plantae has been an important source of traditional medicine in the past and is also enormously used today as an exquisite reservoir for detecting novel bioactive compounds that are potent against hard-to-treat maladies such as cancer. Cancer therapies, especially chemotherapies, are fraught with many factors that are difficult to manage, such as drug resistance, adverse side effects, less selectivity, complexity, etc. Here, we report the results of an exploration of the databases of PubMed, Science Direct, and Google Scholar for bioactive anticancer phytochemicals published between 2010 and 2020. Our report is restricted to new compounds with strong-to-moderate bioactivity potential for which mass spectroscopic structural data are available. Each of the phytochemicals reported in this review was assigned to chemical classes with peculiar anticancer properties. In our survey, we found anticancer phytochemicals that are reported to have selective toxicity against cancer cells, to sensitize MDR cancer cells, and to have multitarget effects in several signaling pathways. Surprisingly, many of these compounds have limited follow-up studies. Detailed investigations into the synthesis of more functional derivatives, chemical genetics, and the clinical relevance of these compounds are required to achieve safer chemotherapy.

1'-Acetoxychavicol Acetate from Alpinia galanga Represses Proliferation and Invasion, and Induces Apoptosis via HER2-signaling in Endocrine-Resistant Breast Cancer Cells

Estrogen receptor-positive breast cancer patients have a good prognosis, but 30% of these patients will experience recurrence due to the development of resistance through various signaling pathways. This study aimed to evaluate the mode of anticancer effects of 1'-acetoxychavicol acetate, which is isolated from the rhizomes of Alpinia galanga in estrogen receptor positive (MCF7) human epidermal growth factor receptor 2-overexpressed (MCF7/HER2), and endocrine-resistant breast cancer cells (MCF7/LCC2 and MCF7/LCC9). 1'-Acetoxychavicol acetate showed antiproliferation in a concentration- and time-dependent fashion and had higher potency in human epidermal growth factor receptor 2-overexpressed cell lines. This was associated with down-regulation of human epidermal growth factor receptor 2, pERK1/2, pAKT, estrogen receptor coactivator, cyclin D1, and MYC proto-oncogene while in vivo and significant reduction in the tumor mass of 1'-acetoxychavicol acetate-treated zebrafish-engrafted breast cancer groups. The anti-invasive effects of 1'-acetoxychavicol acetate were confirmed in vitro by the matrigel invasion assay and with down-regulation of C - X-C chemokine receptor type 4, urokinase plasminogen activator, vascular endothelial growth factor, and basic fibroblast growth factor 2 genes. The down-regulation of urokinase plasminogen activator and fibroblast growth factor 2 proteins was also validated by molecular docking analysis. Moreover, 1'-acetoxychavicol acetate-treated cells exhibited lower expression levels of the anti-apoptotic Bcl-2 and Mcl-1 proteins in addition to enhanced stress-activated kinases/c-Jun N-terminal kinase 1/2 and poly-ADP ribose polymerase cleavage, indicating apoptotic cell induction by 1'-acetoxychavicol acetate. Moreover, 1'-acetoxychavicol acetate had higher potency in human epidermal growth factor receptor 2-overexpressed cell lines regarding its inhibition on human epidermal growth factor receptor 2, pAKT, pERK1/2, PSer¹¹⁸, and PSer¹⁶⁷-ERα proteins. Our findings suggest 1'-acetoxychavicol acetate mediates its anti-cancer effects via human epidermal growth factor receptor 2 signaling pathway.

Stimuli-Responsive Drug Delivery Systems for the Diagnosis and Therapy of Lung Cancer

Lung cancer is the most commonly diagnosed cancer and the leading cause of cancer death worldwide. Numerous drugs have been developed to treat lung cancer patients in recent years, whereas most of these drugs have undesirable adverse effects due to nonspecific distribution in the body. To address this problem, stimuli-responsive drug delivery systems are imparted with unique characteristics and specifically deliver loaded drugs at lung cancer tissues on the basis of internal tumor microenvironment or external stimuli. This review summarized recent studies focusing on the smart carriers that could respond to light, ultrasound, pH, or enzyme, and provided a promising strategy for lung cancer therapy.

Plumbagin reduction by thioredoxin reductase 1 possesses synergy effects with GLUT1 inhibitor on KEAP1-mutant NSCLC cells

Thioredoxin reductase 1 (TrxR1 or TXNRD1) is a major enzyme in cellular redox regulation and is considered as a drug target for cancer therapy. Previous studies have reported that plumbagin caused reactive oxygen species (ROS)-dependent apoptosis via inhibiting TrxR1 activity or being reduced by TrxR1, leading to selectively cancer cell death. However, the mechanism of TrxR1-mediated redox cycling of plumbagin is obscure and the evidence for plumbagin targeting TrxR1 is still lacking. Herein, we demonstrated that TrxR1 catalyzed plumbagin reduction in both selenocysteine (Sec)-dependent and independent manners, and its activity relied on the intact N-terminal motif of TrxR1, but a high-efficiency reduction was supported by the C-terminal thiols. During the redox cycling of plumbagin, excessive ROS production was observed coupled with oxygen. Using LC-MS and TrxR1 mutants, we found that the Sec residue of TrxR1 was modified by plumbagin, which converted the enzyme from antioxidant to pro-oxidant. Furthermore, we evaluated the therapeutic potential of plumbagin in non-small cell lung cancer (NSCLC), and found that Kelch-like ECH-associated protein 1 (KEAP1)-mutant NSCLC cells, which possess constitutive nuclear factor erythroid 2-related factor 2 (NRF2) activity, were insensitive to plumbagin; however, inhibition of glucose transporter 1 (GLUT1) by small-molecule BAY-876 or inhibiting glucose-6-phosphate dehydrogenase (G6PD) by 6-aminonicotinamide (6-AN) overcame the plumbagin-resistance of KEAP1-mutant NSCLC cells. Taken together, this study elucidated the pharmacological mechanism of plumbagin by targeting TrxR1 and revealed the synergy effect of plumbagin and BAY-876, which may be helpful for applying naphthoquinone compounds to chemotherapy, particularly for treating KEAP1-mutant NSCLC cells.

Plumbagin Elicits Cell-Specific Cytotoxic Effects and Metabolic Responses in Melanoma Cells

Melanoma is one of the most malignant skin cancers that require comprehensive therapies, including chemotherapy. A plant-derived drug, plumbagin (PLB), exhibits an anticancer property in several cancers. We compared the cytotoxic and metabolic roles of PLB in A375 and SK-MEL-28 cells, each with different aggressiveness. In our results, they were observed to have distinctive mitochondrial respiratory functions. The primary reactive oxygen species (ROS) source of A375 can be robustly attenuated by cell membrane permeabilization. A375 cell viability and proliferation, migration, and apoptosis induction are more sensitive to PLB treatment. PLB induced metabolic alternations in SK-MEL-28 cells, which included increasing mitochondrial oxidative phosphorylation (OXPHOS), mitochondrial ATP production, and mitochondrial mass. Decreasing mitochondrial OXPHOS and total ATP production with elevated mitochondrial membrane potential (MMP) were observed in PLB-induced A375 cells. PLB also induced ROS production and increased proton leak and non-mitochondria respiration in both cells. This study reveals the relationship between metabolism and cytotoxic effects of PLB in melanoma. PLB displays stronger cytotoxic effects on A375 cells, which exhibit lower respiratory function than SK-MEL-28 cells with higher respiratory function, and triggers cell-specific metabolic changes in accordance with its cytotoxic effects. These findings indicate that PLB might serve as a promising anticancer drug, targeting metabolism.

A dendrimer-functionalized turn-on fluorescence probe based on enzyme-activated debonding feature of azobenzene linkage

The hypoxic feature of tumors has led to researchers developing hypoxia-activated prodrugs and probes that leverage oxidoreductases overexpressed in tumor tissues.

Napabucasin (BBI 608), a potent chemoradiosensitizer in rectal cancer

BACKGROUND

The induction of reactive oxygen species (ROS) represents a viable strategy for enhancing the activity of radiotherapy. The authors hypothesized that napabucasin would increase ROS via its ability to inhibit NAD(P)H:quinone oxidoreductase 1 and potentiate the response to chemoradiotherapy in rectal cancer via distinct mechanisms.

METHOD

Proliferation studies, colony formation assays, and ROS levels were measured in HCT116 and HT29 cell lines treated with napabucasin, chemoradiation, or their combination. DNA damage (pγH2AX), activation of STAT, and downstream angiogenesis were evaluated in both untreated and treated cell lines. Finally, the effects of napabucasin, chemoradiotherapy, and their combination were assessed in vivo with subcutaneous mouse xenograft models.

RESULTS

Napabucasin significantly potentiated the growth inhibition of chemoradiation in both cell lines. Napabucasin increased ROS generation. Inhibition of ROS by N-acetylcysteine decreased the growth inhibitory effect of napabucasin alone and in combination with chemoradiotherapy. Napabucasin significantly increased pγH2AX in comparison with chemoradiotherapy alone. Napabucasin reduced the levels of pSTAT3 and VEGF and inhibited angiogenesis through an ROS-mediated effect. Napabucasin significantly potentiated the inhibition of growth and blood vessel formation by chemoradiotherapy in mouse xenografts.

CONCLUSION

Napabucasin is a radiosensitizer with a novel mechanism of action: increasing ROS production and inhibiting angiogenesis. Clinical trials testing the addition of napabucasin to chemoradiotherapy in rectal cancer are needed.