β-lapachone suppresses the proliferation of human malignant melanoma cells by targeting specificity protein 1

Relevance of BRAF Subcellular Localization and Its Interaction with KRAS and KIT Mutations in Skin Melanoma

Although skin melanoma (SKM) represents only one-quarter of newly diagnosed skin malignant tumors, it presents a high mortality rate. Hence, new prognostic and therapeutic tools need to be developed. This study focused on investigating the prognostic value of the subcellular expression of BRAF, KRAS, and KIT in SKM in correlation with their gene-encoding interactions. In silico analysis of the abovementioned gene interactions, along with their mRNA expression, was conducted, and the results were validated at the protein level using immunohistochemical (IHC) stains. For IHC expression, the encoded protein expressions were checked on 96 consecutive SKMs and 30 nevi. The UALCAN database showed no prognostic value for the mRNA expression level of KRAS and BRAF and demonstrated a longer survival for patients with low mRNA expression of KIT in SKMs. IHC examinations of SKMs confirmed the UALCAN data and showed that KIT expression was inversely correlated with ulceration, Breslow index, mitotic rate, and pT stage. KRAS expression was also found to be inversely correlated with ulceration and perineural invasion. When the subcellular expression of BRAF protein was recorded (nuclear vs. cytoplasmatic vs. mixed nucleus + cytoplasm), a direct correlation was emphasized between nuclear positivity and lymphovascular or perineural invasion. The independent prognostic value was demonstrated for mixed expression of the BRAF protein in SKM. BRAF cytoplasmic predominance, in association with KIT's IHC positivity, was more frequently observed in early-stage nonulcerated SKMs, which displayed a low mitotic rate and a late death event. The present study firstly verified the possible prognostic value of BRAF subcellular localization in SKMs. A low mRNA expression or IHC cytoplasmic positivity for KIT and BRAF might be used as a positive prognostic parameter of SKM. SKM's BRAF nuclear positivity needs to be evaluated in further studies as a possible indicator of perineural and lymphovascular invasion.

CXC Chemokines as Therapeutic Targets and Prognostic Biomarkers in Skin Cutaneous Melanoma Microenvironment

Background

Skin Cutaneous Melanoma (SKCM) is a tumor of the epidermal melanocytes induced by gene activation or mutation. It is the result of the interaction between genetic, constitutional, and environmental factors. SKCM is highly aggressive and is the most threatening skin tumor. The incidence of the disease is increasing year by year, and it is the main cause of death in skin tumors around the world. CXC chemokines in the tumor microenvironment can regulate the transport of immune cells and the activity of tumor cells, thus playing an anti-tumor immunological role and affecting the prognosis of patients. However, the expression level of CXC chemokine in SKCM and its effect on prognosis are still unclear.

Method

Oncomine, UALCAN, GEPIA, STRING, GeneMANIA, cBioPortal, TIMER, TRRUST, DAVID 6.8, and Metascape were applied in our research.

Result

The transcription of CXCL1, CXCL5, CXCL8, CXCL9, CXCL10, and CXCL13 in SKCM tissues were significantly higher than those in normal tissues. The pathological stage of SKCM patients is closely related to the expression of CXCL4, CXCL9, CXCL10, CXCL11, CXCL12, and CXCL13. The prognosis of SKCM patients with low transcription levels of CXCL4, CXCL9, CXCL10, CXCL11, and CXCL13 is better. The differential expression of CXC chemokines is mainly associated with inflammatory response, immune response, and cytokine mediated signaling pathways. Our data indicate that the key transcription factors of CXC chemokines are RELA, NF-κB1 and SP1. The targets of CXC chemokines are mainly LCK, LYN, SYK, MAPK2, MAPK12, and ART. The relationship between CXC chemokine expression and immune cell infiltration in SKCM was closed.

Conclusions

Our research provides a basis for screening SKCM biomarkers, predicting prognosis, and choosing immunotherapy.

β-Lapachone Induces Acute Oxidative Stress in Rat Primary Astrocyte Cultures that is Terminated by the NQO1-Inhibitor Dicoumarol

β-lapachone (β-lap) is reduced in tumor cells by the enzyme NAD(P)H: quinone acceptor oxidoreductase 1 (NQO1) to a labile hydroquinone which spontaneously reoxidises to β-lap, thereby generating reactive oxygen species (ROS) and oxidative stress. To test for the consequences of an acute exposure of brain cells to β-lap, cultured primary rat astrocytes were incubated with β-lap for up to 4 h. The presence of β-lap in concentrations of up to 10 µM had no detectable adverse consequences, while higher concentrations of β-lap compromised the cell viability and the metabolism of astrocytes in a concentration- and time-dependent manner with half-maximal effects observed for around 15 µM β-lap after a 4 h incubation. Exposure of astrocytes to β-lap caused already within 5 min a severe increase in the cellular production of ROS as well as a rapid oxidation of glutathione (GSH) to glutathione disulfide (GSSG). The transient cellular accumulation of GSSG was followed by GSSG export. The β-lap-induced ROS production and GSSG accumulation were completely prevented in the presence of the NQO1 inhibitor dicoumarol. In addition, application of dicoumarol to β-lap-exposed astrocytes caused rapid regeneration of the normal high cellular GSH to GSSG ratio. These results demonstrate that application of β-lap to cultured astrocytes causes acute oxidative stress that depends on the activity of NQO1. The sequential application of β-lap and dicoumarol to rapidly induce and terminate oxidative stress, respectively, is a suitable experimental paradigm to study consequences of a defined period of acute oxidative stress in NQO1-expressing cells.

Growth inhibitory efficacy and anti-aromatase activity of Tabebuia avellanedae in a model for post-menopausal Luminal A breast cancer

Aromatase inhibitors (AIs) represent a treatment option for post-menopausal estrogen receptor-positive (ER⁺) breast cancer as monotherapy, or in combination with cyclin-dependent kinase 4/6 or mTOR inhibitors. Long-term treatment with these agents leads to dose-limiting toxicity and drug resistance. Natural substances provide testable alternatives to current therapy. Tabebuia avellanedae (TA) tree is indigenous to the Amazon rainforest. The inner bark of TA represents a medicinal dietary supplement known as Taheebo. Non-fractionated aqueous extract from TA is an effective growth inhibitor in the Luminal A and triple negative breast cancer models. The quinone derivative naphthofurandione (NFD) is a major bioactive agent in TA. The present study examined the efficacy of finely ground powder from the inner bark of TA, available under the name of Taheebo-NFD-Marugoto (TNM). The ER⁺ MCF-7 cells stably transfected with the aromatase gene MCF-7^AROM represented a model for aromatase-expressing post-menopausal breast cancer. Anchorage-independent colony formation, cell cycle progression, pro-apoptotic caspase 3/7 activity, apoptosis-specific gene expression, aromatase activity and select estradiol (E₂) target gene expression represented the mechanistic end points. Treatment of MCF-7^AROM cells with TNM induced a dose-dependent reduction in E₂-promoted anchorage-independent colony number. Mechanistic assays on TNM-treated MCF-7^AROM cells demonstrated that TNM at a concentration of 10 µg (NFD content: 2 ng), induced S-phase arrest, increased pro-apoptotic caspase 3/7 activity, increased pro-apoptotic BAX and decreased anti-apoptotic BCL-2 gene expression, and inhibited aromatase activity. Additionally, TNM treatment downregulated ESR-1 (gene for ER-α), aromatase and progesterone gene expression and reduced mRNA levels of E₂ target genes pS2, GRB2 and cyclin D1. Inhibition of aromatase activity, based on the NFD content of TNM was superior to the clinical AIs Letrozole and Exemestane. These data demonstrated the potential efficacy of TNM as a nutritional alternative for current therapy of aromatase positive, post-menopausal breast cancer.

β-Lapachone and its iodine derivatives cause cell cycle arrest at G2/M phase and reactive oxygen species-mediated apoptosis in human oral squamous cell carcinoma cells

β-Lapachone is a natural naphthoquinone originally obtained from the bark of the purple Ipe (Tabebuia avellanedae Lor, Bignoniaceae) and its therapeutic potential in human cancer cells has been evaluated in several studies. In this study, we examined the effects of β-lapachone and its 3-iodine derivatives (3-I-α-lapachone and 3-I-β-lapachone) on cell proliferation, cell death, and cancer-related gene expression in human oral squamous cell carcinoma cells. β-Lapachone and its 3-iodine derivatives showed potent cytotoxicity against different types of human cancer cell lines. Indeed, treatment with these compounds induced cell cycle arrest at G₂/M phase, followed by internucleosomal DNA fragmentation, and caused significant increases in phosphatidylserine externalization, caspase-8 and -9 activation, mitochondrial membrane depolarization, reactive oxygen species (ROS) production, and apoptotic cell death morphology. The apoptosis induced by the compounds was prevented by pretreatment with a pan-caspase inhibitor (Z-VAD-FMK) and an antioxidant (N-acetyl-l-cysteine). In vivo, β-lapachone and its 3-iodine derivatives significantly reduced tumor burden and did not alter any of the biochemical, hematological, or histological parameters of the animals. Overall, β-lapachone and its 3-iodine derivatives showed promising cytotoxic activity due to their ability to induce cell cycle arrest at G₂/M phase and promote caspase- and ROS-mediated apoptosis. In addition, β-lapachone and its 3-iodine derivatives were able to suppress tumor growth in vivo, indicating that these compounds may be new antitumor drug candidates.

MicroRNA-342 Prohibits Proliferation and Invasion of Melanoma Cells by Directly Targeting Zinc-Finger E-Box-Binding Homeobox 1

As documented in numerous studies, microRNAs (miRNAs) play key roles in various biological processes associated with melanoma occurrence and development. In this study, we found that miRNA-342 (miR-342) was significantly downregulated in melanoma tissues and cell lines. Additionally, the ectopic expression of miR-342 prohibited the cell proliferation and invasion of melanoma. Moreover, zinc-finger E-box-binding homeobox 1 (ZEB1) was identified as a direct target gene of miR-342 in melanoma. Similar with the results induced by miR-342 overexpression, ZEB1 knockdown attenuated cell proliferation and invasion in melanoma. Furthermore, the restoration of ZEB1 expression reversed the suppressive effects of miR-342 on the proliferation and invasion of melanoma cells. These findings suggest that miR-342 may play tumor-suppressing roles in melanoma, at least partially, by directly inhibiting ZEB1 expression. Therefore, miR-342 may be developed as a potential candidate for the treatment of patients with this aggressive type of cancer.

Carnosic acid, an inducer of NAD(P)H quinone oxidoreductase 1, enhances the cytotoxicity of β-lapachone in melanoma cell lines

NAD(P)H quinone oxidoreductase 1 (NQO1)-dependent antitumor drugs such as β-lapachone (β-lap) are attractive candidates for cancer chemotherapy because several tumors exhibit higher expression of NQO1 than adjacent tissues. Although the association between NQO1 and β-lap has been elucidated, the effects of a NQO1-inducer and β-lap used in combination remain to be clarified. It has previously been reported that melanoma cell lines have detectable levels of NQO1 expression and are sensitive to NQO1-dependent drugs such as 17-allylamino-17-demethoxygeldanamycin. The present study was conducted to investigate the involvement of NQO1 in β-lap-mediated toxicity and the utility of combination treatment with a NQO1-inducer and β-lap in malignant melanoma cell lines. Decreased expression or inhibition of NQO1 caused these cell lines to become less sensitive to β-lap, indicating a requirement of NQO1 activity for β-lap-mediated toxicity. Of note was that carnosic acid (CA), a compound extracted from rosemary, was able to induce further expression of NQO1 through NF-E2 related factor 2 (NRF2) stabilization, thus significantly enhancing the cytotoxicity of β-lap in all of the melanoma cell lines tested. Taken together, the data presented in the current study indicated that the NRF2-NQO1 axis may have potential value as a therapeutic target in malignant melanoma to improve the rate of clinical response to NQO1-dependent antitumor drugs.

Natural Compound Licochalcone B Induced Extrinsic and Intrinsic Apoptosis in Human Skin Melanoma (A375) and Squamous Cell Carcinoma (A431) Cells

Licochalcone B (Lico B), which is normally isolated from the roots of Glycyrrhiza inflata (Chinese Licorice), generally classified into organic compounds including retrochalcones. Potential pharmacological properties of Lico B include anti-inflammatory, anti-bacterial, anti-oxidant, and anti-cancer activities. However, its biological effects on melanoma and squamous cell carcinoma (SCC) are unknown. Based on these known facts, this study investigated the role of Lico B in apoptosis, through the extrinsic and intrinsic pathways and additional regulation of specificity protein 1 in human skin cancer cell lines. Annexin V/7-aminoactinomycin D staining, western blot analysis, mitochondrial membrane potential assay, and an anchorage-independent cell transformation assay demonstrated that Lico B treatment of human melanoma and SCC cells significantly inhibited cell proliferation and induced apoptotic cell death. More specifically, Lico B induced apoptosis through the regulation of specificity protein 1 and apoptosis-related proteins including CCAAT/enhancer-binding protein homologous protein, death receptors, and poly (ADP-ribose) polymerase. These results indicate that Lico B has apoptotic effect on A375 and A431 skin cancer cells, suggesting the potential value of Lico B for the treatment of human melanoma and SCC. Copyright © 2017 John Wiley & Sons, Ltd.

Pharmacokinetic and safety evaluation of MB12066, an NQO1 substrate

Objective

This study evaluated the pharmacokinetics (PKs) and safety of a newly developed β-lapachone (MB12066) tablet, a natural NAD(P)H:quinone oxidoreductase 1 (NQO1) substrate, in healthy male volunteers.

Methods

In a randomized, double-blind, multiple-dose, two-treatment study, 100 mg MB12066 or placebo was given twice daily for 8 days to groups of eight or three fasted healthy male subjects, respectively, followed by serial blood sampling. Plasma concentrations for β-lapachone were determined using liquid chromatography–tandem mass spectrometry. PK parameters were obtained with non-compartmental analysis. Tolerability was assessed based on physical examinations, vital signs, clinical laboratory tests, and electrocardiograms.

Results

Following a single 100 mg MB12066 oral dose, maximum plasma concentration (C_max) of β-lapachone was 3.56±1.55 ng/mL, and the median (range) time to reach C_max was 3 h (2–5 h). After the 8 days of 100 mg twice daily repeated dosing was completed, mean terminal half-life was determined to be 18.16±3.14 h, and the mean area under the plasma concentration vs time curve at steady state was 50.44±29.68 ng·h/mL. Accumulation index was 2.72±0.37. No serious adverse events (AEs) were reported, and all reported intensities of AEs were mild.

Conclusion

The results demonstrated that MB12066 was safe and well tolerated in healthy volunteers and that there were no serious AEs. Accumulation in plasma with twice-daily administration was associated with a 2.72 accumulation ratio.

β-Lapachone Inhibits Lung Metastasis of Colorectal Cancer by Inducing Apoptosis of CT26 Cells

Background: β-Lapachone is a quinone-containing compound found in red lapacho (Tabebuia impetiginosa, syn. T avellanedae) trees. Lapacho has been used in traditional medicine by several South and Central American indigenous people to treat various types of cancer. The purpose of this study was to investigate the antimetastatic properties of β-lapachone and the underlying mechanisms using colon cancer cells. Methods: This research used metastatic murine colon cancer cell lines, colon 26 (CT26) and colon 38 (MC38). A WST assay, annexin V assay, cell cycle analysis, wound healing assay, invasion assay, western blot analysis, and real-time reverse transcription–polymerase chain reaction were performed to examine the effects of β-lapachone on metastatic phenotypes and molecular mechanisms. The effect of β-lapachone on lung metastasis was assessed in a mouse experimental metastasis model. Results: We found that the inhibition of proliferation of the colon cancer cell lines by β-lapachone was due to the induction of apoptosis and cell cycle arrest. β-Lapachone induced the apoptosis of CT26 cells through caspase-3, -8, and -9 activation; poly(ADP-ribose) polymerase cleavage; and downregulation of the Bcl-2 family in a dose- and time-dependent manner. In addition, a low concentration of β-lapachone decreased the cell migration and invasion by decreasing the expression of matrix metalloproteinases-2 and -9, and increased the expression of tissue inhibitors of metalloproteinases-1 and -2. Moreover, β-lapachone treatment regulated the expression of epithelial-mesenchymal transition markers such as E- and N-cadherin, vimentin, β-catenin, and Snail in CT26 cells. In the mouse experimental metastasis model, β-lapachone significantly inhibited the lung metastasis of CT26 cells. Conclusions: Our results demonstrated the inhibitory effect of β-lapachone on colorectal lung metastasis. This compound may be useful for developing therapeutic agents to treat metastatic cancer.