LW6, a hypoxia-inducible factor 1 inhibitor, selectively induces apoptosis in hypoxic cells through depolarization of mitochondria in A549 human lung cancer cells

Hypoxia-inducible factor 1-alpha is a driving mechanism linking chronic obstructive pulmonary disease to lung cancer

Patients with chronic obstructive pulmonary disease (COPD), irrespective of their smoking history, are more likely to develop lung cancer than the general population. This is mainly because COPD is characterized by chronic persistent inflammation and hypoxia, which are the risk factors for lung cancer. However, the mechanisms underlying this observation are still unknown. Hypoxia-inducible factor 1-alpha (HIF-1α) plays an important role in the crosstalk that exists between inflammation and hypoxia. Furthermore, HIF-1α is the main regulator of somatic adaptation to hypoxia and is highly expressed in hypoxic environments. In this review, we discuss the molecular aspects of the crosstalk between hypoxia and inflammation, showing that HIF-1α is an important signaling pathway that drives COPD progression to lung cancer. Here, we also provide an overview of HIF-1α and its principal regulatory mechanisms, briefly describe HIF-1α-targeted therapy in lung cancer, and summarize substances that may be used to target HIF-1α at the level of COPD-induced inflammation.

The hypoxia-inducible factor 1 inhibitor LW6 mediates the HIF-1α/PD-L1 axis and suppresses tumor growth of hepatocellular carcinoma in vitro and in vivo

The low survival rate of hepatocellular carcinoma (HCC) remains a major challenge for clinicians and patients, and its progression may be related to hypoxia-inducible factor (HIF) and PD-L1. LW6 is a drug that inhibits hypoxia by reducing HIF-1α accumulation and gene transcriptional activity. However, its effect and regulatory mechanism in HCC remain to be revealed, especially under hypoxic conditions. The HIF-1α and PD-L1 expression in HCC specimens and paracarcinoma tissues was evaluated by a tissue microarray (TMA). The effects of LW6 were evaluated by cell viability, colony formation, and Transwell assays and xenografted nude mice. Cell cycle and apoptosis of HCC cells were detected by flow cytometry. The effects of LW6 on HIF-1α signaling and its targets PD-L1 and VEGF were evaluated through qRT-PCR, Western blots, Cell transfection, Transwell migration and invasion assays, immunohistochemistry, immunofluorescence and luciferase assays. In this study, we found that LW6 had antiproliferative effects on HCC and promoted HCC cell apoptosis, inhibited their migration and invasion, and affected their cell cycle. LW6 dramatically decreased HIF-1α expression through the VHL-dependent proteasome system pathway, inhibited HIF-1α transcriptional activation, and reduced PD-L1 expression by inhibiting EGFR pathway activation. These results suggest that LW6 can promote apoptosis of HCC cells by inhibiting HIF-1α, inhibit tumor angiogenesis, and downregulate the expression of PD-L1, which is an effective choice for the treatment of HCC. Moreover, inhibiting the hypoxic microenvironment combined with immunotherapy is expected to be a potentially effective strategy.

Resistance to Gemcitabine in Pancreatic Ductal Adenocarcinoma: A Physiopathologic and Pharmacologic Review

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive tumor with a poor prognosis and inadequate response to treatment. Many factors contribute to this therapeutic failure: lack of symptoms until the tumor reaches an advanced stage, leading to late diagnosis; early lymphatic and hematic spread; advanced age of patients; important development of a pro-tumoral and hyperfibrotic stroma; high genetic and metabolic heterogeneity; poor vascular supply; a highly acidic matrix; extreme hypoxia; and early development of resistance to the available therapeutic options. In most cases, the disease is silent for a long time, andwhen it does become symptomatic, it is too late for ablative surgery; this is one of the major reasons explaining the short survival associated with the disease. Even when surgery is possible, relapsesare frequent, andthe causes of this devastating picture are the low efficacy ofand early resistance to all known chemotherapeutic treatments. Thus, it is imperative to analyze the roots of this resistance in order to improve the benefits of therapy. PDAC chemoresistance is the final product of different, but to some extent, interconnected factors. Surgery, being the most adequate treatment for pancreatic cancer and the only one that in a few selected cases can achieve longer survival, is only possible in less than 20% of patients. Thus, the treatment burden relies on chemotherapy in mostcases. While the FOLFIRINOX scheme has a slightly longer overall survival, it also produces many more adverse eventsso that gemcitabine is still considered the first choice for treatment, especially in combination with other compounds/agents. This review discusses the multiple causes of gemcitabine resistance in PDAC.

Regulatory effects of HIF-1α and HO-1 in hypoxia-induced proliferation of pulmonary arterial smooth muscle cells in yak

Hypoxia-inducible factor-1α (HIF-1α) and heme oxygenase-1 (HO-1) are important transcription regulators in hypoxic cells and for maintaining cellular homeostasis, but it is unclear whether they participate in hypoxia-induced excessive proliferation of yak pulmonary artery smooth muscle cells (PASMCs). In this study, we identified distribution of HIF-1α and HO-1 in yak lungs. Immunohistochemistry and immunofluorescence results revealed that both HIF-1α and HO-1 were mainly concentrated in the medial layer of small pulmonary arteries. Furthermore, under induced-hypoxic conditions, we investigated HIF-1α and HO-1 protein expression and studied their potential involvement in yak PASMCs proliferation and apoptosis. Western blot results also showed that both factors significantly increased in age-dependent manner and upregulated in hypoxic PASMCs (which exhibited obvious proliferation and anti-apoptosis phenomena). HIF-1α up-regulation by DMOG increased the proliferation and anti-apoptosis of PASMCs, while HIF-1α down-regulation by LW6 decreased proliferation and promoted apoptosis. More so, treatment with ZnPP under hypoxic conditions down-regulated HO-1 expression, stimulated proliferation, and resisted apoptosis in yak PASMCs. Taken together, our study demonstrated that both HIF-1α and HO-1 participated in PASMCs proliferation and apoptosis, suggesting that HO-1 is important for inhibition of yak PASMCs proliferation while HIF-1α promoted hypoxia-induced yak PASMCs proliferation.

Screening of radiotracer for diagnosis of colorectal cancer liver metastasis based on MACC1-SPON2

Background

Metastasis-associated in colon cancer 1 (MACC1) and Spondin2 (SPON2) are newly discovered oncogenes, but little is known about their role in colorectal cancer(CRC) liver metastases. PET has become an important molecular imaging technology due to its high sensitivity and quantifiability. In particular, its targeted, specific molecular probes can detect biological behaviors. This study was designed to evaluate the different biological properties of ¹⁸F-FDG, ¹⁸F-FLT, and ¹⁸F-FMISO PET. The value of the CRC liver metastasis model explores the correlation and potential mechanisms of three tracers uptakes with tumor-related biological characteristics.

Methods

Human CRC cell lines(LoVo and HCT8), were cultured for in vitro radionuclide uptake experiments to compare the molecular imaging features of colorectal cancer cells with different metastatic potentials. Two kinds of cells were injected into the spleen of nude mice to establish a liver metastasis model. After the tumor formation, three kinds of tracer PET images were performed to evaluate the characteristics of live PET imaging of high and low liver metastasis colorectal cancer models. The expression levels of MACC1 and SPON2 in tissues were detected by immunohistochemistry and Western blot. Correlation between tracer uptake and expression of MACC1 and SPON2 in liver metastases was assessed by linear regression analysis.

Results

The uptake rate of in vitro three tracers uptake experiments was LoVo > HCT8. Micro-PET scan showed no significant difference between the ¹⁸F-FDG SUV values of the two cells (P > 0.05); there was significant difference between the ¹⁸F-FLT and ¹⁸F-FMISO SUV values (P < 0.05). All in vivo FLT and FMISO SUV values were significantly higher in LoVo tumors than in HCT8 tumors. The results of Western blot and immunohistochemistry showed that the expression levels of MACC1 and SPON2 in LoVo liver metastasis were higher than those in HCT8 (P < 0.05). The ¹⁸F-FLT SUVmax ratio was significantly correlated with the expression of MACC1 and SPON2 in hepatic metastases (r = 0.737, P = 0.0026; r = 0.842, P = 0.0002). The ¹⁸F-FMISO SUVmax ratio was only significantly correlated with the expression of MACC1 in hepatic metastasis (r = 0.770, P = 0.0013).

Conclusions

Early screening with ¹⁸F-FLT and ¹⁸F-FMISO tracers has important clinical value for the efficient diagnosis and treatment of colorectal cancer liver metastases.

Sublethal heat stress-induced O-GlcNAcylation coordinates the Warburg effect to promote hepatocellular carcinoma recurrence and metastasis after thermal ablation

The malignant transformation of residual hepatocellular carcinoma (HCC) cells after thermal ablation is considered as the main factor promoting postoperative HCC progression, which greatly limits the improvement of long-term survival, and at present there is no effective targeted therapeutic strategies. The Warburg effect is a metabolic feature correlated highly with malignant transformation (e.g. epithelial-to-mesenchymal transition [EMT]). Here, we showed that sublethal heat stress triggered a stronger Warburg effect of HCC cells, which contributed to the thermotolerance and invasion of HCC cells. Sublethal heat stress-induced O-GlcNAcylation was involved in this process. Such enhanced Warburg effect in HCC cells may be eliminated through O-GlcNAcylation inhibition, resulting in impaired thermotolerance and EMT, and thereby preventing tumor recurrence and metastasis of HCC-bearing mice after insufficient thermal ablation. Finally, we present evidence that sublethal heat stress-induced O-GlcNAcylation regulates the Warburg effect in HCC cells by promoting hypoxia-inducible factor 1α (HIF-1α) stability. In conclusion, the present study suggests that O-GlcNAcylation coordinates the Warburg effect to promote HCC progression after thermal ablation, which may serve as a novel potential target for controlling postoperative HCC recurrence and metastasis.

Antioxidative Stress: Inhibiting Reactive Oxygen Species Production as a Cause of Radioresistance and Chemoresistance

Radiotherapy and chemotherapy are the most effective nonsurgical treatments for cancer treatment. They usually induce regulated cell death by increasing the level of reactive oxygen species (ROS) in tumour cells. However, as intracellular ROS concentration increases, many antioxidant pathways are concurrently upregulated by cancer cells to inhibit ROS production, ultimately leading to drug resistance. Understanding the mechanism of antioxidant stress in tumour cells provides a new research direction for overcoming therapeutic resistance. In this review, we address (1) how radiotherapy and chemotherapy kill tumour cells by increasing the level of ROS, (2) the mechanism by which ROS activate antioxidant pathways and the subsequent cellular mitigation of ROS in radiotherapy and chemotherapy treatments, and (3) the potential research direction for targeted treatment to overcome therapeutic resistance.

Immunogenomic Profiling and Classification of Prostate Cancer Based on HIF-1 Signaling Pathway

The HIF-1 signaling pathway plays an important role in the pathogenesis of cancer. Many studies have explored the progression of prostate cancer (PCa) under hypoxic conditions based on transcriptome data; few have uncovered the immunogenomic profiling and prostate cancer classification based on the HIF-1 signaling pathway. This pathway may help to identify the optimal subset of PCa patients responsive to immunotherapy/chemotherapy. The immunogenomic PCa subsets were classified based on profiling of the HIF-1 signaling pathway, using four publicly available PCa datasets. Three PCa subtypes that named as HIF-1 High (HIF-1_H), HIF-1 Medium (HIF-1_M), and HIF-1 Low (HIF-1_L) were identified. Functional enrichment was analyzed in each subtype. Several cancer-associated and immune-related pathways were hyperactivated in the HIF-1_H subtypes. In contrast, HIF-1_L subtypes were enriched in cell cycle and cell repair. Compared with other subtypes, HIF-1_H subtypes have greater immune cell infiltration, anti-tumor immune activity, and better survival prognosis. The submap and TIDE algorithm were used to predict the clinical response to immune checkpoint blockade, and GDSC was employed to screen potential chemotherapeutic targets for the treatment of PCa. Several chemotherapy drugs were identified in the GDSC dataset, including ABT 888, Temsirolimus, and EHT 1864. Meanwhile, HIF-1_H was defined as an early PCa marker, which is more likely to respond to immunotherapy. The identification of immunogenomic PCa subtypes based on the HIF-1 signaling pathway has potential clinical implications for PCa treatment. Immunopositive PCa subtypes will help to explore the reasons for the poor response of PCa to immunotherapy, and it is expected that immunotherapy will guide the personalized treatment of PCa patients.

MicroRNA-130a targeting hypoxia-inducible factor 1 alpha suppresses cell metastasis and Warburg effect of NSCLC cells under hypoxia

MicroRNAs have been demonstrated to play critical role in the development of non-small cell lung cancer (NSCLC) and hypoxia is a common hallmark of NSCLC. MiRNA-130a-3p (miR-130a) is a well-known tumor suppressor, and we intended to explore the role and mechanism of miR-130a in NSCLC cells under hypoxia. We used real-time quantitative polymerase chain reaction method to measure miR-130a expression, and found that miR-130a was downregulated in human NSCLC tumors and cell lines (A549 and H1299), accompanied with upregulation of hypoxia-inducible factor 1 alpha (HIF1A), a marker of hypoxia. Besides, miR-130a low expression was associated with tumor burden and poor overall survival. Moreover, miR-130a expression was even downregulated in hypoxia-treated A549 and H1299 cells. Ectopic expression of miR-130a suppressed Warburg effect, migration and invasion in hypoxic A549 and H1299 cells, as evidenced by decreased glucose consumption, lactate production, hexokinase 2 expression, and numbers of migration cells and invasion cells analyzed by commercial glucose and lactate assay kits, western blotting and transwell assays. Furthermore, overexpression of miR-130a restrained xenograft tumor growth of A549 cells in mice. However, recovery of HIF1A could reverse the suppressive effect of miR-130a overexpression on cell migration, invasion and Warburg effect in hypoxic A549 and H1299 cells. Mechanically, dual-luciferase reporter assay, RNA immunoprecipitation and RNA pull-down assay confirmed a target relationship between miR-130a and HIF1A. Collectively, we demonstrated an anti-tumor role of miR-130a in NSCLC cells under hypoxia through targeting HIF1A, suggesting a potential target for the interfering of NSCLC.

Activation of TWIST Transcription by Chromatin Remodeling Protein BRG1 Contributes to Liver Fibrosis in Mice

Liver fibrosis is a complex pathophysiological process to which many different cell types contribute. Endothelial cells play versatile roles in the regulation of liver fibrosis. The underlying epigenetic mechanism is not fully appreciated. In the present study, we investigated the role of BRG1, a chromatin remodeling protein, in the modulation of endothelial cells in response to pro-fibrogenic stimuli in vitro and liver fibrosis in mice. We report that depletion of BRG1 by siRNA abrogated TGF-β or hypoxia induced down-regulation of endothelial marker genes and up-regulation of mesenchymal marker genes in cultured endothelial cells. Importantly, endothelial-specific BRG1 deletion attenuated CCl₄ induced liver fibrosis in mice. BRG1 knockdown in vitro or BRG1 knockout in vivo was accompanied by the down-regulation of TWIST, a key regulator of endothelial phenotype. Mechanistically, BRG1 interacted with and was recruited to the TWIST promoter by HIF-1α to activate TWIST transcription. BRG1 silencing rendered a more repressive chromatin structure surrounding the TWIST promoter likely contributing to TWIST down-regulation. Inhibition of HIF-1α activity dampened liver fibrosis in mice. Similarly, pharmaceutical inhibition of TWIST alleviated liver fibrosis in mice. In conclusion, our data suggest that epigenetic activation of TWIST by BRG1 contributes to the modulation of endothelial phenotype and liver fibrosis. Therefore, targeting the HIF1α-BRG1-TWIST axis may yield novel therapeutic solutions to treat liver fibrosis.

DNA damage response signaling pathways and targets for radiotherapy sensitization in cancer

Radiotherapy is one of the most common countermeasures for treating a wide range of tumors. However, the radioresistance of cancer cells is still a major limitation for radiotherapy applications. Efforts are continuously ongoing to explore sensitizing targets and develop radiosensitizers for improving the outcomes of radiotherapy. DNA double-strand breaks are the most lethal lesions induced by ionizing radiation and can trigger a series of cellular DNA damage responses (DDRs), including those helping cells recover from radiation injuries, such as the activation of DNA damage sensing and early transduction pathways, cell cycle arrest, and DNA repair. Obviously, these protective DDRs confer tumor radioresistance. Targeting DDR signaling pathways has become an attractive strategy for overcoming tumor radioresistance, and some important advances and breakthroughs have already been achieved in recent years. On the basis of comprehensively reviewing the DDR signal pathways, we provide an update on the novel and promising druggable targets emerging from DDR pathways that can be exploited for radiosensitization. We further discuss recent advances identified from preclinical studies, current clinical trials, and clinical application of chemical inhibitors targeting key DDR proteins, including DNA-PKcs (DNA-dependent protein kinase, catalytic subunit), ATM/ATR (ataxia-telangiectasia mutated and Rad3-related), the MRN (MRE11-RAD50-NBS1) complex, the PARP (poly[ADP-ribose] polymerase) family, MDC1, Wee1, LIG4 (ligase IV), CDK1, BRCA1 (BRCA1 C terminal), CHK1, and HIF-1 (hypoxia-inducible factor-1). Challenges for ionizing radiation-induced signal transduction and targeted therapy are also discussed based on recent achievements in the biological field of radiotherapy.

Mitochondrial Mechanisms Underlying Tolerance to Fluctuating Oxygen Conditions: Lessons from Hypoxia-Tolerant Organisms

Oxygen (O2) is essential for most metazoan life due to its central role in mitochondrial oxidative phosphorylation (OXPHOS), which generates >90% of the cellular adenosine triphosphate. O2 fluctuations are an ultimate mitochondrial stressor resulting in mitochondrial damage, energy deficiency, and cell death. This work provides an overview of the known and putative mechanisms involved in mitochondrial tolerance to fluctuating O2 conditions in hypoxia-tolerant organisms including aquatic and terrestrial vertebrates and invertebrates. Mechanisms of regulation of the mitochondrial OXPHOS and electron transport system (ETS) (including alternative oxidases), sulphide tolerance, regulation of redox status and mitochondrial quality control, and the potential role of hypoxia-inducible factor (HIF) in mitochondrial tolerance to hypoxia are discussed. Mitochondrial phenotypes of distantly related animal species reveal common features including conservation and/or anticipatory upregulation of ETS capacity, suppression of reactive oxygen species (ROS)-producing electron flux through ubiquinone, reversible suppression of OXPHOS activity, and investment into the mitochondrial quality control mechanisms. Despite the putative importance of oxidative stress in adaptations to hypoxia, establishing the link between hypoxia tolerance and mitochondrial redox mechanisms is complicated by the difficulties of establishing the species-specific concentration thresholds above which the damaging effects of ROS outweigh their potentially adaptive signaling function. The key gaps in our knowledge about the potential mechanisms of mitochondrial tolerance to hypoxia include regulation of mitochondrial biogenesis and fusion/fission dynamics, and HIF-dependent metabolic regulation that require further investigation in hypoxia-tolerant species. Future physiological, molecular and genetic studies of mitochondrial responses to hypoxia, and reoxygenation in phylogenetically diverse hypoxia-tolerant species could reveal novel solutions to the ubiquitous and metabolically severe problem of O2 deficiency and would have important implications for understanding the evolution of hypoxia tolerance and the potential mitigation of pathological states caused by O2 fluctuations.

Metformin and LW6 impairs pancreatic cancer cells and reduces nuclear localization of YAP1

The poor survival rate of pancreatic cancer is still a major challenge for the clinicians and their patients. In this study, we evaluated the efficacy of metformin, an inhibitor of oxidative phosphorylation, in combination with LW6, which impairs malate dehydrogenase 2 activities, in treating pancreatic cancer cells. We observed that this combinational therapy significantly reduced cell proliferation, migration, and significantly induced cell death when compared to cells treated by each monotherapy or Sham. In addition, we found that the combination of metformin and LW6 increased the phosphorylation of yes-associated protein 1 at serine 127 and attenuated the nuclear localization of this transcription factor. This combinatorial treatment also decreased the level of cellular yes-associated protein 1. This suggests that metformin in combination with LW6 impairs pancreatic cancer cells and reduces nuclear localization of yes-associated protein 1.

Evaluation of [18F]FDG/[18F]FLT/[18F]FMISO-based micro-positron emission tomography in detection of liver metastasis in human colorectal cancer

INTRODUCTION

Positron emission tomography (PET) is extensively used in clinical oncology for tumor detection. This study aimed to explore the application of the radiotracers [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG), 3'-deoxy-3'- [¹⁸F]fluorothymidine ([¹⁸F]FLT), and [¹⁸F]fluoromisonidazole ([¹⁸F]FMISO) in the diagnosis and monitoring of hepatic metastasis in human colorectal cancer (CRC).

METHODS

A mouse model of human CRC with hepatic metastasis was established by intrasplenic implantation of human CRC cell lines LoVo or HCT8. Metastatic potential of these two cell lines was evaluated by wound healing assay in vitro and survival analysis. Uptake of radiotracers between LoVo and HCT8 cells and uptake of radiotracers in the resulting mouse tumor models were examined by in vivo and in vitro experiments. Uptake of each radiotracer in hepatic metastatic lesions was quantified and expressed as standard uptake value (SUV). Protein expression of multiple tumor biomarkers was determined in metastatic lesions. The correlation between tracer uptake and tumor marker expression was evaluated using linear regression.

RESULTS

LoVo cells exhibited a stronger metastatic potential and a higher radiotracer uptake ability than HCT8 cells, as evidenced by significantly greater wound closure percentage, shorter survival, higher incidence of liver metastases, and higher cellular radiotracer levels in LoVo cells or LoVo cell-xenografted mice. SUV values of [¹⁸F]FLT and [¹⁸F]FMISO, but not [¹⁸F]FDG, in LoVo cell-derived metastatic lesions were significantly greater than those in HCT8 lesions. Mechanistically, the expression of MACC1, HIF-1α, and GLUT-1(metastasis associated in colon cancer 1, MACC1; hypoxia-inducible factor 1-alpha, HIF-1α; and glucose transporter 1, GLUT-1, respectively) in LoVo cell-derived metastatic lesions was more effectively induced than in HCT8-derived ones. A linear regression analysis demonstrated significant positive correlations between [¹⁸F]FLT/[¹⁸F]FMISO uptake and tumor biomarker expression in metastatic tissues.

CONCLUSIONS

[¹⁸F]FLT and [¹⁸F]FMISO-based PET imaging may serve as a promising method for early detection and monitoring of hepatic metastasis in patients with CRC.

Development of a Ternary Solid Dispersion Formulation of LW6 to Improve the In Vivo Activity as a BCRP Inhibitor: Preparation and In Vitro/In Vivo Characterization

LW6 (3-[2-(4-adamantan-1-yl-phenoxy)-acetylamino]-4-hydroxy-benzoic acid methyl ester) is a potent inhibitor of drug efflux by the breast cancer resistance protein (BCRP). However, its poor aqueous solubility leads to low bioavailability, which currently limits in vivo applications. Therefore, the present study aimed to develop ternary solid dispersion (SD) formulations in order to enhance the aqueous solubility and dissolution rate of LW6. Various SDs of LW6 were prepared using a solvent evaporation method with different drug/excipient ratios. The solubility and dissolution profiles of LW6 in different SDs were examined, and F8-SD which is composed of LW6, poloxamer 407, and povidone K30 at a weight ratio of 1:5:8 was selected as the optimal SD. The structural characteristics of F8-SD were also examined using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM). In the acidic to neutral pH range, F8-SD achieved rapid dissolution with a drug release of 76–81% within 20 min, while the dissolution of pure LW6 was negligible. The XRPD patterns indicated that F8-SD probably enhanced the solubility and dissolution of LW6 by changing the drug crystallinity to an amorphous state, in addition to the solubilizing effect of the hydrophilic carriers. Furthermore, F8-SD significantly improved the oral bioavailability of topotecan, which is a BCRP substrate, in rats. The systemic exposure of topotecan was enhanced approximately 10-fold by the concurrent use of F8-SD. In conclusion, the ternary SD formulation of LW6 with povidone K30 and poloxamer 407 appeared to be effective at improving the dissolution and in vivo effects of LW6 as a BCRP inhibitor.

Triterpenoid corosolic acid attenuates HIF-1 stabilization upon cobalt (II) chloride-induced hypoxia in A549 human lung epithelial cancer cells

Hypoxia-inducible factor-1 is a target for the management of cancer. Here, the anti-proliferation properties of corosolic acid (CA) against A549 human lung epithelial cancer cells in CoCl₂-induced hypoxia is reported. CA was isolated from the roots of Salvia syriaca based on a bioassay-guided isolation platform and identified by 1D and 2D NMR experiments. Several cytotoxicies and genotoxicity analyses were performed using MTT, DAPI, cell cycle, DNA ladder, and annexin V/PI detection. Cobalt chloride (CoCl₂) was used to stimulate hypoxia. The adaptation of A549 cells to a stimulated hypoxic condition in the presence of CA was evaluated. CA decreased the growth of A549 cells with an IC₅₀ of 12 μg/mL at 48 h. Also, chromatin condensation and DNA fragmentation were detected as signs of apoptosis occurrence. CA induced ~85% apoptosis and even 1% necrosis. The expression of hypoxia-inducible factor-1 α (HIF-1α), HIF-1β and downstream genes was strongly suppressed in the presence of CA in CoCl₂-stimulated hypoxia condition. Results indicated that CA has remarkable cytotoxicity against the cancerous cell in hypoxia condition and may be regarded for preparation of new formulations for possible uses as supplement and medicine in cancer therapy.

Metformin attenuates hypoxia-induced resistance to cisplatin in the HepG2 cell line

Hepatoblastoma is the most commonly occurring liver tumor in children. Preoperative chemotherapy and surgery have improved treatment outcomes; however, further improvements are required in the treatment of advanced cases. Recently, the efficacy of transarterial chemoembolization (TACE) has garnered attention. TACE increases the local concentration of drugs by transcatheterically administering antitumor agents, and induces necrosis in the tumor by embolizing the feeding artery. However, studies have revealed that tumors exhibit resistance to anticancer drugs in hypoxic environments. Metformin is a drug used to treat type 2 diabetes; however, recent reports have indicated that it may also exhibit antitumor effects in various cancer cell lines. These effects are hypothesized to be mediated by the activation of adenosine monophosphate-activated protein kinase and reduction of mammalian target of rapamycin signaling, but these effects occur at high concentrations that are not suitable for use in a clinical setting. The potential efficacy of metformin at increased physiological concentrations has not been evaluated. The present study investigated the therapeutic effect of low concentrations of metformin in combination with cisplatin on liver cancer HepG2 cells in hypoxic conditions. HepG2 cells were treated with cisplatin alone, metformin alone, or a combination of these two drugs and cultured in normoxia or hypoxia. Treatment with either 5 µM cisplatin or 1 mM metformin alone did not significantly affect cell proliferation or apoptosis in hypoxic conditions. However, when 5 µM cisplatin was combined with 1 mM metformin, a significant inhibition of cell proliferation and induction of apoptosis was observed in hypoxic HepG2 cells. In conclusion, a low concentration of metformin attenuates hypoxia-induced resistance to cisplatin in HepG2 cells. Selective delivery of an effective dose of metformin to a hepatoblastoma tumor may be achievable and clinically useful with TACE.

Noninvasive evaluation of 18F-FDG/18F-FMISO-based Micro PET in monitoring hepatic metastasis of colorectal cancer

This study aimed to explore the application of two radiotracers (¹⁸F-fluorodeoxyglucose (FDG) and ¹⁸F-fluoromisonidazole (FMISO)) in monitoring hepatic metastases of human colorectal cancer (CRC). Mouse models of CRC hepatic metastases were established by implantation of the human CRC cell lines LoVo and HT29 by intrasplenic injection. Wound healing and Transwell assays were performed to examine cell migration and invasion abilities. Radiotracer-based cellular uptake in vitro and micro-positron emission tomography imaging of liver metastases in vivo were performed. The incidence of liver metastases in LoVo-xenografted mice was significantly higher than that in HT29-xenografted ones. The SUVmax/mean values of ¹⁸F-FMISO, but not ¹⁸F-FDG, in LoVo xenografts were significantly greater than in HT29 xenografts. In vitro, LoVo cells exhibited stronger metastatic potential and higher radiotracer uptake than HT29 cells. Mechanistically, the expression of HIF-1α and GLUT-1 in LoVo cells and LoVo tumor tissues was remarkably higher than in HT29 cells and tissues. Linear regression analysis demonstrated correlations between cellular ¹⁸F-FDG/¹⁸F-FMISO uptake and HIF-1α/GLUT-1 expression in vitro, as well as between ¹⁸F-FMISO SUVmax and GLUT-1 expression in vivo. ¹⁸F-FMISO uptake may serve as a potential biomarker for the detection of liver metastases in CRC, whereas its clinical use warrants validation.

Montelukast inhibits hypoxia inducible factor-1α translation in prostate cancer cells

Through regulating the expression of hundreds of genes, hypoxia-inducible factor -1(HIF-1) plays a critical role in hypoxic adaption of cancer cells and is considered as a target for cancer therapy. Here we show that montelukast, a clinical leukotriene receptor antagonist for the treatment of asthma, inhibits hypoxia or CoCl₂-induced HIF-1α activation and reduces its protein expression in prostate cancer cells. However, the other two leukotriene receptor antagonists, pranlukast and zafirlukast, cannot decrease HIF-1α protein, which indicates that montelukast-induced downregulation of HIF-1α is not mediated by leukotriene receptor. Neither proteasome inhibitor MG132 nor the lysosomal inhibitor chloroquine (CQ) can block montelukast-induced downregulation of HIF-1α protein. Interestingly, GSK2606414, a PKR-like endoplasmic reticulum kinase (PERK) inhibitor, abrogates montelukast-induced downregulation of HIF-1α under hypoxic conditions. However, montelukast increases phosphorylation of eIF-2α at Ser51. Moreover, montelukast inhibits the proliferation of prostate cancer cells, which can be reversed by overexpression of HIF-1α protein. In conclusion, we identify montelukast may be used as a novel agent for the treatment of prostate cancer by decreasing HIF-1α protein translation.

In vivo evaluation of the effects of simultaneous inhibition of GLUT-1 and HIF-1α by antisense oligodeoxynucleotides on the radiosensitivity of laryngeal carcinoma using micro 18F-FDG PET/CT

Purpose

Hypoxia-inducible factor 1α (HIF-1α) and glucose transporter-1 (GLUT-1) are two important hypoxic markers associated with the radioresistance of cancers including laryngeal carcinoma. We evaluated whether the simultaneous inhibition of GLUT-1 and HIF-1α expression improved the radiosensitivity of laryngeal carcinoma. We explored whether the expression of HIF-1α and GLUT-1 was correlated with 2′-deoxy-2’-[18F]fluoro-D-glucose (¹⁸F-FDG) uptake and whether ¹⁸F-FDG positron emission tomography-computed tomography (PET/CT) was appropriate for early evaluation of the response of laryngeal carcinoma to targeted treatment in vivo.

Materials and Methods

To verify the above hypotheses, an in vivo model was applied by subcutaneously injecting Hep-2 (2 × 107/mL × 0.2 mL) and Tu212 cells (2 × 107/mL × 0.2 mL) into nude mice. The effects of HIF-1α antisense oligodeoxynucleotides (AS-ODNs) (100 μg) and GLUT-1 AS-ODNs (100 μg) on the radiosensitivity of laryngeal carcinoma were assessed by tumor volume and weight, microvessel density (MVD), apoptosis index (AI) and necrosis in vivo based on a full factorial (2³) design. ¹⁸F-FDG-PET/CT was taken before and after the treatment of xenografts. The relationships between HIF-1α and GLUT-1 expression and ¹⁸F-FDG uptake in xenografts were estimated and the value of ¹⁸F-FDG-PET/CT was assessed after treating the xenografts.

Results

10 Gy X-ray irradiation decreased the weight of Hep-2 xenografts 8 and 12 days after treatment, and the weights of Tu212 xenografts 8 days after treatment. GLUT-1 AS-ODNs decreased the weight of Tu212 xenografts 12 days after treatment. There was a synergistic interaction among the three treatments (GLUT-1 AS-ODNs, HIF-1α AS-ODNs and 10Gy X-ray irradiation) in increasing apoptosis, decreasing MVD, and increasing necrosis in Hep-2 xenografts 8 days after treatment (p < 0.05) and in Tu212 xenografts 12 days after treatment (p < 0.001). Standardized uptake value (tumor/normal tissue)( SUVmaxT/N) did not show a statistically significant correlation with GLUT1 and HIF-1α expression and therapeutic effect (necrosis, apoptosis).

Conclusions

Simultaneous inhibition of HIF-1α and GLUT-1 expression might increase the radiosensitivity of laryngeal carcinoma, decreasing MVD, and promoting apoptosis and necrosis. ¹⁸F-FDG-PET/CT wasn't useful in evaluating the therapeutic effect on laryngeal cancer in this animal study.

Impact of pretreatment whole-tumor perfusion computed tomography and 18F-fluorodeoxyglucose positron emission tomography/computed tomography measurements on local control of non-small cell lung cancer treated with stereotactic body radiotherapy

This study aimed to investigate the correlation between the average iodine density (AID) detected by dual-energy computed tomography (DE-CT) and the maximum standardized uptake value (SUV_max) yielded by [¹⁸F] fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) for non-small cell lung cancer (NSCLC) treated with stereotactic body radiotherapy (SBRT). Seventy-four patients with medically inoperable NSCLC who underwent both DE-CT and ¹⁸F-FDG PET/CT before SBRT (50‒60 Gy in 5‒6 fractions) were followed up after a median interval of 24.5 months. Kaplan-Meier analysis was used to determine associations between local control (LC) and variables, including AID, SUV_max, tumor size, histology, and prescribed dose. The median AID and SUV_max were 18.64 (range, 1.18-45.31) (100 µg/cm³) and 3.2 (range, 0.7-17.6), respectively. No correlation was observed between AID and SUV_max Two-year LC rates were 96.2% vs 75.0% (P = 0.039) and 72.0% vs 96.2% (P = 0.002) for patients classified according to high vs low AID or SUV_max, respectively. Two-year LC rates for patients with adenocarcinoma vs squamous cell carcinoma vs unknown cancer were 96.4% vs 67.1% vs 92.9% (P = 0.008), respectively. Multivariate analysis identified SUV_max as a significant predictor of LC. The 2-year LC rate was only 48.5% in the subgroup of lower AID and higher SUV_max vs >90% (range, 94.4-100%) in other subgroups (P = 0.000). Despite the short follow-up period, a reduction in AID and subsequent increase in SUV_max correlated significantly with local failure in SBRT-treated NSCLC patients. Further studies involving larger populations and longer follow-up periods are needed to confirm these results.

Discovery of LW6 as a new potent inhibitor of breast cancer resistance protein

PURPOSE

The present study aimed to discover a new potent BCRP inhibitor overcoming multidrug resistance.

METHODS

Effects of LW6 on the functional activity and gene expression of two major efflux transporters, BCRP and P-gp, were evaluated by using MDCKII cells overexpressing each transporter (MDCKII-BCRP and MDCKII-MDR1). Its effects on the cytotoxicity and pharmacokinetics of co-administered anticancer drugs were also evaluated in transfected cells and rats, respectively.

RESULTS

In MDCKII-BCRP cells overexpressing BCRP, LW6 enhanced significantly (p < 0.05) the cellular accumulation of mitoxantrone, a BCRP substrate, and was more potent than Ko143, a well-known BCRP inhibitor. LW6 also down-regulated BCRP expression at concentrations of 0.1-10 µM. Furthermore, cells became more susceptible to the cytotoxicity of anticancer drugs in the presence of LW6. The CC50 values of mitoxantrone and doxorubicin were reduced by three- and tenfold, respectively, in MDCKII-BCRP cells, while LW6 did not affect the cytotoxicity of anticancer drugs in MDCKII-mock cells lacking BCRP transporter. Furthermore, LW6 improved the oral exposure of methotrexate by twofold in rats. In contrast to BCRP, LW6 had no inhibition effect on the functional activity and gene expression of P-gp.

CONCLUSION

LW6 was newly identified as a potent BCRP inhibitor and could be useful to reduce the multidrug resistance of cancer cells via the inhibition of BCRP-mediated drug efflux as well as the down-regulation of BCRP expression.