Inhibition of Lung Carcinoma A549 Cell Growth by Knockdown of Hexokinase 2 In Situ and In Vivo

A pan-cancer analysis of the role of hexokinase II (HK2) in human tumors

More and more evidence show that HK2 is closely related to tumors. But no pan-cancer analysis is available. This paper aimed to explore the potential roles of HK2 across thirty-three tumors based on the datasets of the cancer genome Atlas (TCGA) and gene expression omnibus. HK2 is highly expressed in most tumors and related to the progression of some tumors. HK2 expression was associated with the infiltration of T follicular helper cells for the TCGA tumors of uveal melanoma, breast invasive carcinoma (BRCA), breast invasive carcinoma-luminalA (BRCA-LumA), head and neck squamous cell carcinoma (HNSC), head and neck squamous cell carcinoma with HPV positive (HNSC-HPV⁺), and cancer-associated fibroblasts for the tumors of brain lower grade glioma and stomach adenocarcinoma. Our first pan-cancer study offers a relatively comprehensive understanding of the roles of HK2 in different tumors.

Virtual Screening and Biological Activity Evaluation of New Potent Inhibitors Targeting Hexokinase-II

Hexokinase-II (HK-II), the rate-limiting step enzyme in the glycolysis pathway, expresses high levels of cancer cells compared with normal cells. Due to its pivotal role in the different aspects of cancer physiology including cellular proliferation, metastasis, and apoptosis, HK-II provides a new therapeutic target for cancer therapy. The structure-based virtual screening targeting HK-II was used to hit identifications from small molecule databases, and the select compounds were further evaluated in biological assays. Forty-seven compounds with the lowest binding energies were identified as potential HK-II inhibitors. Among them, nine compounds displayed the highest cytotoxicity to three different cancer cells. Based on the mechanism study, compounds 4244-3659 and K611-0094 showed an obvious inhibitory effect on the HK-II enzyme. This study identified two potential inhibitors of HK-II and can be helpful for developing potential drugs targeting HK-II in tumor therapy.

Hexokinase 2 Inhibition and Biological Effects of BNBZ and Its Derivatives: The Influence of the Number and Arrangement of Hydroxyl Groups

Hexokinase 2 (HK2), an enzyme of the sugar kinase family, plays a dual role in glucose metabolism and mediating cancer cell apoptosis, making it an attractive target for cancer therapy. While positive HK2 expression usually promotes cancer cells survival, silencing or inhibiting this enzyme has been found to improve the effectiveness of anti-cancer drugs and even result in cancer cell death. Previously, benitrobenrazide (BNBZ) was characterized as a potent HK2 inhibitor with good anti-cancer activity in mice, but the effect of its trihydroxy moiety (pyrogallol-like) on inhibitory activity and some cellular functions has not been fully understood. Therefore, the main goal of this study was to obtain the parent BNBZ (2a) and its three dihydroxy derivatives 2b–2d and to conduct additional physicochemical and biological investigations. The research hypothesis assumed that the HK2 inhibitory activity of the tested compounds depends on the number and location of hydroxyl groups in their chemical structure. Among many studies, the binding affinity to HK2 was determined and two human liver cancer cell lines, HepG2 and HUH7, were used and exposed to chemicals at various times: 24 h, 48 h and 72 h. The study showed that the modifications to the structures of the new BNBZ derivatives led to significant changes in their activities. It was also found that these compounds tend to aggregate and exhibit toxic effects. They were found to contribute to: (a) DNA damage, (b) increased ROS production, and (c) disruption of cell cycle progression. It was observed that, HepG2, occurred much more sensitive to the tested chemicals than the HUH7 cells; However, regardless of the used cell line it seems that the increase in the expression of HK2 in cancer cells compared to normal cells which have HK2 at a very low level, is a serious obstacle in anti-cancer therapy and efforts to find the effective inhibitors of this enzyme should be intensified.

Methylation-associated silencing of miR-9-1 promotes nasopharyngeal carcinoma progression and glycolysis via HK2

Characteristically, cancer cells metabolize glucose through aerobic glycolysis, known as the Warburg effect. Accumulating evidence suggest that during cancer formation, microRNAs (miRNAs) could regulate such metabolic reprogramming. In the present study, miR‐9‐1 was identified as significantly hypermethylated in nasopharyngeal carcinoma (NPC) cell lines and clinical tissues. Ectopic expression of miR‐9‐1 inhibited NPC cell growth and glycolytic metabolism, including reduced glycolysis, by reducing lactate production, glucose uptake, cellular glucose‐6‐phosphate levels, and ATP generation in vitro and tumor proliferation in vivo. HK2 (encoding hexokinase 2) was identified as a direct target of miR‐9‐1 using luciferase reporter assays and Western blotting. In NPC cells, hypermethylation regulates miR‐9‐1 expression and inhibits HK2 translation by directly targeting its 3' untranslated region. MiR‐9‐1 overexpression markedly reduced HK2 protein levels. Restoration of HK2 expression attenuated the inhibitory effect of miR‐9‐1 on NPC cell proliferation and glycolysis. Fluorescence in situ hybridization results indicated that miR‐9‐1 expression was an independent prognostic factor in NPC. Our findings revealed the role of the miR‐9‐1/HK2 axis in the metabolic reprogramming of NPC, providing a potential therapeutic strategy for NPC.

MicroRNA-615 functions as a tumor suppressor in osteosarcoma through the suppression of HK2

At present, the regulatory mechanisms of various microRNAs (miRNAs/miRs) have been elucidated in human cancers including osteosarcoma (OS). This study mainly focused on the role of miR-615 in OS, which has not yet been reported. Ninety-two OS tissues and normal samples were used in this study. Human osteoblast hFOB1.19 cells and OS cell line HOS were utilized to detect the expression of miR-615. The expression of miR-615 and gene expression were assessed by RT-qPCR and western blot analysis. Transwell, MTT and luciferase reporter assays were used to investigate the regulatory mechanism of miR-615 in OS. The results revealed that miR-615 expression was reduced in OS tissues and cells, and was associated with poor clinical outcomes and prognosis in OS patients. In addition, overexpression of miR-615 restrained cell viability and metastasis in OS. Furthermore, hexokinase 2 (HK2) was confirmed as a direct target of miR-615. Upregulation of HK2 was detected in OS tissues. The upregulation of HK2 weakened the tumor-suppressive effect of miR-615 in OS. Moreover, miR-615 blocked epithelial-mesenchymal transition (EMT) and inactivated the PI3K/AKT pathway in OS. To conclude, miR-615 acts as a tumor suppressor in OS, thus miR-615 can be used as a target for OS treatment.

Long Non-Coding RNA DUXAP8 Facilitates Cell Viability, Migration, and Glycolysis in Non-Small-Cell Lung Cancer via Regulating HK2 and LDHA by Inhibition of miR-409-3p

Purpose

Long non-coding RNAs (lncRNAs) were confirmed to play important roles in human cancers. In this study, we explored the functional role of lncRNA double homeobox A pseudogene 8 (DUXAP8) in non-small-cell lung cancer (NSCLC).

Methods

Real-time quantitative PCR (RT-qPCR) was used to detect DUXAP8 and microRNA-409-3p (miR-409-3p) expression. CCK-8, cell colony formation assay, and Transwell migration assay were performed to measure cell growth and migration, respectively. The expression of the relative proteins was detected by Western blot. Cell glycolysis was determined by glucose uptake, adenosine triphosphate (ATP) concentration, lactate generation, extracellular acidification rate and oxygen consumption rate assays. Bioinformatics analysis and dual-luciferase reporter assay were used to measure the interaction among DUXAP8, miR-409-3p, hexokinase 2 (HK2) and lactate dehydrogenase A (LDHA). In vivo, subcutaneous tumor formation assay was performed in the nude mice.

Results

DUXAP8 was highly expressed in NSCLC, while miR-409-3p was downregulated. High expression of DUXAP8 was positively related to the grade division and negatively associated with the 5-year survival rate of NSCLC patients. Downregulated DUXAP8 significantly suppressed cell growth, metastasis and glycolysis. Besides, DUXAP8 sponged miR-409-3p to promote HK2 and LDHA expression. DUXAP8 promoted cell viability, migration and glycolysis by regulating miR-409-3p/HK2/LDHA axis. Moreover, DUXAP8 downregulation markedly inhibited tumor growth in vivo.

Conclusion

Our findings demonstrated that DUXAP8 served as an oncogene in the progression of NSCLC.

Unlocking the Potential of HK2 in Cancer Metabolism and Therapeutics

Glycolysis is a tightly regulated process in which several enzymes, such as Hexokinases (HKs), play crucial roles. Cancer cells are characterized by specific expression levels of several isoenzymes in different metabolic pathways and these features offer possibilities for therapeutic interventions. Overexpression of HKs (mostly of the HK2 isoform) have been consistently reported in numerous types of cancer. Moreover, deletion of HK2 has been shown to decrease cancer cell proliferation without explicit side effects in animal models, which suggests that targeting HK2 is a viable strategy for cancer therapy. HK2 inhibition causes a substantial decrease of glycolysis that affects multiple pathways of central metabolism and also destabilizes the mitochondrial outer membrane, ultimately enhancing cell death. Although glycolysis inhibition has met limited success, partly due to low selectivity for specific isoforms and excessive side effects of the reported HK inhibitors, there is ample ground for progress. The current review is focused on HK2 inhibition, envisaging the development of potent and selective anticancer agents. The information on function, expression, and activity of HKs is presented, along with their structures, known inhibitors, and reported effects of HK2 ablation/inhibition. The structural features of the different isozymes are discussed, aiming to stimulate a more rational approach to the design of selective HK2 inhibitors with appropriate drug-like properties. Particular attention is dedicated to a structural and sequence comparison of the structurally similar HK1 and HK2 isoforms, aiming to unveil differences that could be explored therapeutically. Finally, several additional catalytic- and non-catalytic roles on different pathways and diseases, recently attributed to HK2, are reviewed and their implications briefly discussed.

MiR-125b-5p suppresses the bladder cancer progression via targeting HK2 and suppressing PI3K/AKT pathway

Bladder cancer (BCa) is identified as the most common malignant solid cancer in the urogenital tract. Recently, dysregulation of miRNAs has received more attention because of its extensive role in the carcinogenesis of BCa. This research was designed to verify how miR-125b-5p be involved in BCa development. The expression of miR-125b-5p was detected in 52 pairs of BCa specimens and adjacent normal bladder specimens. The effects of miR-125b-5p on BCa viability, migration, and apoptosis in vitro were examined. We then examined directly target gene(s) of miR-125b-5p in BCa cells. Our data demonstrated that miR-125b-5p was decreased in BCa tissues and cell lines. Patients with low miR-125b-5p expression had obviously shorter 5-year survival time. Lower miR-125b-5p expression was significant correlated with distant metastasis, tumor size and lymph node metastasis. Ectopic expression of miR-125b-5p inhibited the BCa cell viability and migration and induced cell apoptosis. Furthermore, HK2 was confirmed regulated by miR-125b-5p. HK2 recovered miR-125b-5p-mediated suppression of BCa cell viability and migration. In addition, miR-125b-5p also exhibited suppressive effect on PI3K/AKT pathway. Overall, these data indicate that miR-125b-5p played a role in the suppressive effect on BCa by targeting HK2 through suppressing PI3K/AKT pathway and offer a potential therapeutic target for BCa.

Roles of GLUT-1 and HK-II expression in the biological behavior of head and neck cancer

The Warburg effect plays an important role in the proliferation and invasion of malignant tumors. Glucose transporter 1 and hexokinase II are two key energy transporters involved in mediating the Warburg effect. This review will analyze the mechanisms of these two markers in their effects on the biological behavior of head and neck cancer.

MicroRNA-384-3p inhibits retinal neovascularization through targeting hexokinase 2 in mice with diabetic retinopathy

Diabetic retinopathy (DR) presents a microvascular complication of diabetes, which may contribute to visual impairment. The treatment of DR is still controversial. Accumulating studies have reported the role of microRNAs (miRs) in DR. This study aims to explore the functions of microRNA-384-3p (miR-384-3p) in retinal neovascularization by targeting hexokinase 2 (HK2) in mice with DR. A total of 43 C57BL/6 male mice were selected and divided into normal ( n = 16) and DR ( n = 27) groups. Retinal microvascular endothelial cells (RMECs) were collected from the normal and DR mice and mainly treated with a miR-384-3p mimic, a miR-384-3p inhibitor, small interfering RNA (siRNA) against HK2 and HK2 overexpression plasmids to understand the underlying regulatory mechanisms of miR-384-3p. The relationship between miR-384-3p and HK2 was determined by dual-luciferase reporter assay. The miR-384-3p expression and the mRNA and the protein expressions of HK2 and CD31 in retinal tissues and cells were evaluated using reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot assay. Cell proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Tube formation was observed by conducting a tube formation experiment. HK2 is a target gene of miR-384-3p. The DR mice showed higher expression of HK2 and CD31 but lower expression of miR-384-3p. The miR-384-3p mimic and siRNA-HK2 reduced the expression of HK2, decreased cell proliferation and tube formation of RMECs, whereas the miR-384-3p inhibitor could reverse these trends. Our study demonstrates that overexpression of miR-384-3p inhibits retinal neovascularization in DR mice via inhibition of HK2.

MiR-216a-5p/Hexokinase 2 axis regulates uveal melanoma growth through modulation of Warburg effect

Hexokinase-2 (HK2), the initial as well as the rate-limiting step in glycolysis, is overexpressed in many human cancers, and correlates with poor clinical outcomes. Aerobic glycolysis is a hallmark of cancer, and drugs targeting its enzymes, including HK2, are being developed. However, the mechanisms of HK2 inhibition and the physiological significance of the HK2 inhibitors in cancer cells are rarely reported. Here, we show that microRNA-216a-5p (miR-216a-5p) inhibits HK2 expression by directly targeting its 3'-UTR in uveal melanoma cells. Through inhibition of HK2, miR-216a-5p dampens glycolysis by reducing HK activity, glucose uptake, lactate production, ATP generation, extracellular acidification rate (ECAR), and increasing oxygen consumption rate (OCR) in uveal melanoma cells. Importantly, glycolysis regulated by miR-216a-5p is critical for its regulating uveal melanoma tumor growth both in vitro and in vivo. miR-216a-5p expression is negatively correlated with HK2 expression and predicts better outcome in uveal melanoma patients. Our findings provide clues regarding the role of miR-216a-5p as a tumor suppressor in uveal melanoma through the inhibition of HK2. Targeting HK2 through miR-216a-5p could be a promising therapeutic strategy in uveal melanoma.

Hexokinase 2 enhances the metastatic potential of tongue squamous cell carcinoma via the SOD2-H2O2 pathway

The glycolytic enzyme hexokinase (HK2), which is aberrantly expressed in various types of tumours, is associated with metastasis. However, its role in the progression and metastasis of tongue squamous cell carcinoma (TSCC) remains unclear. The results of our study showed that HK2 expression is often deregulated in TSCC patients. Increased HK2 expression was associated with tumour stage, clinical stage, lymph node metastasis, but not pathological grade, and reduced overall survival. Microarray and western blotting analyses revealed increases in HK2 expression in TSCC cells with higher metastatic potential. The following effects were observed with HK2 knockdown: inhibition of cell migration and invasion; reduced SOD2 activity and intracellular H₂O₂ levels; suppression of pERK1/2, Slug and Vimentin expression; and inhibition of tumour growth and lung metastasis in vivo. Conversely, HK2 overexpression promoted cell migration and invasion, increased SOD2 activity and intracellular H₂O₂, and enhanced expression of pERK1/2, Slug and Vimentin. Thus, our results demonstrate that deregulation of HK2 expression has an important function in the progression of TSCC and may serve as a biomarker of its metastatic potential in TSCC patients. HK2 enhances the metastatic potential of TSCC by stimulating the SOD2-H₂O₂ pathway.

Suppression of reactive oxygen species-mediated ERK and JNK activation sensitizes dihydromyricetin-induced mitochondrial apoptosis in human non-small cell lung cancer

Nonsmall cell lung cancer (NSCLC) is the most common type of lung cancer with a high mortality rate and still remains a therapeutic challenge. A strategy for targeting NSCLC is to identify agents that are effective against NSCLC cells while sparing normal cells. Dihydromyricetin (DHM) is the major flavonoid component derived from Ampelopsis grossedentata, which has a long history of use in medicine. Herein, the molecular mechanisms by which DHM exerts its anticancer effects against NSCLC cells were investigated. Results from MTS, colony formation, Western blot, flow cytometric, and JC-1 mitochondrial membrane potential assays revealed that DHM showed a selective cytotoxic effect against NSCLC cells (A549 and H1975), but not against normal lung (WI-38) fibroblasts, by inducing apoptosis. DHM-induced cell apoptosis occurred through Bcl-w suppression-mediated mitochondrial membrane depolarization, caspase-9/-7/-3 activation, and poly(ADP-ribose) polymerase (PARP) cleavage in A549 and H1975 cells. Moreover, treatment of A549 and H1975 cells with DHM induced increase of intracellular peroxide and sustained activation of extracellular signal-regulated kinase (ERK)1/2 and c-Jun N-terminal kinase (JNK)1/2, and the reactive oxygen species scavenger, N-acetylcysteine (NAC), reversed DHM-induced ERK and JNK activation. Furthermore, treatment of cells with specific inhibitors of ERK and JNK or NAC significantly promoted the DHM-induced activation of caspase-9/-7/-3 and PARP cleavage and also sensitized the antitumorigenic effect of DHM on NSCLC cells. These findings define and support a novel function of DHM of inducing mitochondrion-derived apoptosis in human NSCLC cells, and a combination of DHM with ERK and JNK inhibitors should be a good strategy for preventing NSCLC proliferation. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1426-1438, 2017.

Targeting hexokinase II as a possible therapy for cholangiocarcinoma

Overexpression of hexokinase 2 (HKII) has been demonstrated in various cancers. A number of in vitro and in vivo studies in several cancers show the significance of HKII in many cellular processes including proliferation, metastasis and apoptosis. However, the role of HKII in Opisthorchis viverrini (Ov) associated cholangiocarcinoma (CCA) is still unknown. In the present study, the expression and roles of HKII were determined in Ov associated CCA. The expression of HKII was investigated in 82 patients with histologically proven CCAs by immunohistochemistry. HKII was distinctively expressed in CCA tissues. It was rarely expressed in normal bile duct epithelium, but was expressed in hyperplastic/dysplastic and in 82% of CCA bile ducts. The observation was confirmed in the Ov associated hamster model. Suppression of HKII expression using siRNA significantly decreased cell proliferation, migration and invasion of CCA cell lines. Similar results were obtained using lonidamine (LND), an inhibitor of HK. LND significantly inhibited growth of 4 CCA cell lines tested in dose and time dependent fashion. Comparison the cytotoxic effects of LND and siRNA-HKII suggests the off target of LND above 100 μM. In addition, LND in non-cytotoxic doses could suppress migration and invasion of CCA cells. These results indicate the association of HKII in cholangiocarcinogenesis and progression and suggest the possibility of HKII as a therapeutic target for CCA.