Byung Kook Kwak

3-Bromopyruvate: A New Targeted Antiglycolytic Agent and a Promise for Cancer Therapy

The pyruvate analog, 3-bromopyruvate, is an alkylating agent and a potent inhibitor of glycolysis. This antiglycolytic property of 3-bromopyruvate has recently been exploited to target cancer cells, as most tumors depend on glycolysis for their energy requirements. The anticancer effect of 3-bromopyruvate is achieved by depleting intracellular energy (ATP) resulting in tumor cell death. In this review, we will discuss the principal mechanism of action and primary targets of 3-bromopyruvate, and report the impressive antitumor effects of 3-bromopyruvate in multiple animal tumor models. We describe that the primary mechanism of 3-bromopyruvate is via preferential alkylation of GAPDH and that 3-bromopyruvate mediated cell death is linked to generation of free radicals. Research in our laboratory also revealed that 3-bromopyruvate induces endoplasmic reticulum stress, inhibits global protein synthesis further contributing to cancer cell death. Therefore, these and other studies reveal the tremendous potential of 3-bromopyruvate as an anticancer agent.

Ultrasound-guided direct delivery of 3-bromopyruvate blocks tumor progression in an orthotopic mouse model of human pancreatic cancer

Studies in animal models of cancer have demonstrated that targeting tumor metabolism can be an effective anticancer strategy. Previously, we showed that inhibition of glucose metabolism by the pyruvate analog, 3-bromopyruvate (3-BrPA), induces anticancer effects both in vitro and in vivo. We have also documented that intratumoral delivery of 3-BrPA affects tumor growth in a subcutaneous tumor model of human liver cancer. However, the efficacy of such an approach in a clinically relevant orthotopic tumor model has not been reported. Here, we investigated the feasibility of ultrasound (US) image-guided delivery of 3-BrPA in an orthotopic mouse model of human pancreatic cancer and evaluated its therapeutic efficacy. In vitro, treatment of Panc-1 cells with 3-BrPA resulted in a dose-dependent decrease in cell viability. The loss of viability correlated with a dose-dependent decrease in the intracellular ATP level and lactate production confirming that disruption of energy metabolism underlies these 3-BrPA-mediated effects. In vivo, US-guided delivery of 3-BrPA was feasible and effective as demonstrated by a marked decrease in tumor size on imaging. Further, the antitumor effect was confirmed by (1) a decrease in the proliferative potential by Ki-67 immunohistochemical staining and (2) the induction of apoptosis by terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphospate nick end labeling staining. We therefore demonstrate the technical feasibility of US-guided intratumoral injection of 3-BrPA in a mouse model of human pancreatic cancer as well as its therapeutic efficacy. Our data suggest that this new therapeutic approach consisting of a direct intratumoral injection of antiglycolytic agents may represent an exciting opportunity to treat patients with pancreas cancer.

Transcatheter Arterial Embolization in Patients with Kidney Diseases: an Overview of the Technical Aspects and Clinical Indications

Therapeutic embolization is defined as the voluntary occlusion of one or several vessels, and this is achieved by inserting material into the lumen to obtain transient or permanent thrombosis in the downstream vascular bed. There are a number of indications for this approach in urological practice, in particular for the patients with parenchymatous or vascular kidney disease. In this review, we present the different embolization techniques and the principally employed occluding agents, and then we present the principal clinical indications and we discuss other pathologies that may benefit from this non-invasive therapy. The complications, side effects and main precautions associated with this approach are also described.

Spontaneous tumor regression in a syngeneic rat model of liver cancer: implications for survival studies.

PURPOSE To characterize tumor growth of N1S1 cells implanted into the liver of Sprague-Dawley rats to determine if this model could be used for survival studies. These results were compared with tumor growth after implantation with McA-RH7777 cells. MATERIALS AND METHODS N1S1 or McA-RH7777 cells were implanted into the liver of Sprague-Dawley rats (n = 20 and n = 12, respectively) using ultrasound (US) guidance, and tumor growth was followed by using US. Serum profiles of 19 cytokines were compared in naive versus tumor-bearing rats. RESULTS Both types of tumors were visible on US 1 week after tumor implantation, but the mean tumor volume of N1S1 tumors was larger compared to McA-RH7777 tumors (231 mm(3) vs 82.3 mm(3), respectively). Tumor volumes in both groups continued to increase, reaching means of 289 mm(3) and 160 mm(3) in N1S1 and McA-RH7777 groups, respectively, 2 weeks after tumor implantation. By week 3, tumor volumes had decreased considerably, and six tumors (50%) in the McA-RH7777 had spontaneously regressed, versus two (10%) in the N1S1 group. Tumor volumes continued to decrease over the following 3 weeks, and complete tumor regression of all tumors was seen 5 weeks and 6 weeks after tumor implantation in the McA-RH7777 and N1S1 groups, respectively. In an N1S1-implanted rat, multiple cytokines that have been shown to correlate with the ability of the tumor to survive in a hostile environment were increased by as much as 50%, whereas the average increase in cytokine levels was 90%. These findings suggest that the net cytokine environment favors an antitumor immune response. A similar trend was observed in a rat with a McA-RH7777 tumor, and the increase in cytokine levels was considerably more pronounced, with an average increase of 320%. CONCLUSIONS The model of N1S1 cell implantation in the liver of Sprague-Dawley rats is not ideal for survival studies and should only be used with great caution in short-term studies that involve cancer therapies.

Antiglycolytic Therapy Combined with an Image-guided Minimally Invasive Delivery Strategy for the Treatment of Breast Cancer

PURPOSE The antiglycolytic agent 3-bromopyruvate (3-BrPA) promotes anticancer effects in multiple tumor models. This study evaluated the therapeutic efficacy of ultrasound (US)-guided intratumoral delivery of 3-BrPA in an orthotopic tumor model of breast cancer. MATERIALS AND METHODS Human breast cancer cell line MDA MB 231 was used for in vitro and in vivo studies. The anticancer effect of 3-BrPA was evaluated by viability assay, quantification of adenosine triphosphate (ATP) and lactate levels, and activity of matrix metalloproteinase (MMP)-9. In animal experiments, 15 nude mice with MDA MB 231 breast tumors were divided into three groups for US-guided intratumoral treatment with 1.75 mM 3-BrPA (group 1), 5 mM 3-BrPA (group 2), and saline solution (group 3). Tumor size was measured and subjected to histopathologic examination. RESULTS In vitro, treatment with 3-BrPA resulted in a dose-dependent decrease in cell viability. A decrease in ATP and lactate levels, invasion, and MMP9 activity and expression was observed after treatment with concentrations of 3-BrPA that did not affect cell viability. In vivo, a significant difference in tumor volume was observed between 3-BrPA-treated and control animals. At the end of the study, tumor volumes in the 3-BrPA groups were 1,876 mm(3)±346 and 426 mm(3)±180 in the 1.75-mM and 5-mM 3-BrPA groups, respectively, versus 4,447 mm(3)±571 in the control group (P< .05). CONCLUSIONS US-guided intratumoral injection of 3-BrPA effectively blocks breast cancer progression in an orthotopic mouse tumor model.

Letter to the Editor re: Superselective arterial embolisation with a liquid polyvinyl alcohol copolymer in patients with acute gastrointestinal haemorrhage

Sir, We read with great interest the article by Lenhart and colleagues recently published in European Radiology and reporting effectiveness of selective arterial embolisation using Onyx® in patients with acute gastrointestinal bleeding [1]. We have several comments. First of all, we would like to congratulate the authors for their study which represents the first series to date reporting results on arterial embolotherapy with Onyx® as an embolic agent in the gastrointestinal tract. Until now, the only available data on the use of this embolic material for peripheral applications came from case reports. Indeed, Onyx® is a new liquid embolic agent composed of ethylene-vinyl alcohol copolymer dissolved in dimethyl sulphoxide (DMSO), with emerging applications in neurovascular procedures, predominantly embolisation of cerebral aneurysms and arteriovenous malformations [2]. The main advantages of Onyx® are its nonadhesive properties, high radiopacity, and long solidification periods, which, compared with acrylic glues, make the embolisation procedure more controllable and predictable. However, the authors did not bring to attention several important disadvantageous characteristics of the use of Onyx®. First, DMSO can cause severe vasospasm if injected rapidly. This is most likely to occur early in the procedure and can be avoided by using no more than 0.2 ml of DMSO in the first minute of injection. Even if the authors reported a total injection time of DMSO and Onyx® of 10 min on average for their procedure, in our experience, the duration of injection is often much longer and varies depending on the amount of Onyx® used. Secondly, DMSO is volatile and is excreted via respiration and sweat. This has a typical smell not unlike that of diabetic ketoacidosis and may last a few days. The patient and ward staff should be warned to expect this. Lastly, the use of Onyx® has cost implications as it is much more expensive than alternative embolic materials and it requires specific DMSO-compatible microcatheters. The prohibitive costs of using Onyx® have led to its restricted use in neuroradiology in most of the institutions around the world. In conclusion, we think this embolic agent is very promising but the important cost aspect needs to be borne in mind when there are other cheaper alternatives that would be as effective and faster when used on an emergency basis.

Abstract 4462: Induction of apoptosis by 3-bromopyruvate involves endoplasmic reticulum (ER) stress and overcomes autophagy response in human hepatocellular carcinoma cell line Hep3B

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Background: Autophagy is a cellular response to adverse conditions that also plays a role in resistance to chemotherapy in cancer cells. Resistance renders systemic chemotherapy generally ineffective against human hepatocellular carcinoma (HCC). The HCC cell line Hep3B is deficient in key apoptotic regulators (p53, Fas) and shows differential apoptotic response to various chemotherapeutic agents. The antiglycolytic agent, 3-bromopyruvate (3-BrPA) is known to induce cell death in human HCC cell lines and has shown potent antitumor activity. In the current study we investigated the intracellular response of Hep3B cells to 3-BrPA treatment and compared it with another HCC cell line, SK-Hep1. Methods: We examined the intracellular effect of 3-BrPA by measuring endoplasmic reticulum (ER) stress using quantitative RT-PCR (qRT-PCR) and immunoblotting. The ultrastructural changes were observed by electron microscopy (EM). Apoptosis was evaluated by TUNEL assay and caspase-3 activation. Results: 3-BrPA treatment induced ER stress and inhibited protein synthesis in a dose and time dependent manner in both the HCC cell lines. EM revealed that 3-BrPA treatment resulted in the initiation of autophagy in Hep3B cells and apoptotic blebbing in SK-Hep1 cells. However, Hep3B cells overcame the initial autophagic response and finally progressed to apoptosis. Conclusions: SK-Hep1 cells upon 3-BrPA treatment underwent the classic pathway of apoptosis whereas Hep3B cells employed autophagy as a defense mechanism but failed to resist apoptosis. We conclude that 3-BrPA treatment promotes apoptosis in human HCC cell lines irrespective of their differential response associated with the status of key apoptotic regulators. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4462.