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.

Human hepatocellular carcinoma in a mouse model: assessment of tumor response to percutaneous ablation by using glyceraldehyde-3-phosphate dehydrogenase antagonists.

PURPOSE: To characterize tumor response to percutaneous injection of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) antagonists in a mouse model of human hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Animal experiments were approved by the Johns Hopkins University Animal Care and Use Committee. Luciferase (luc) gene-expressing Hep3B tumor-bearing athymic nude mice were randomly divided into four groups of six mice each. Tumor-specific GAPDH inhibition was achieved by using percutaneous injection of GAPDH antagonists-3-bromopyruvate (3-BrPA) or GAPDH-specific short hairpin RNA (shRNA). Tumor response to treatment was assessed by using bioluminescence imaging and analysis of GAPDH function and apoptotic markers (caspase-3, caspase-9, and positive staining for terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphospate nick end labeling). HCC samples from 34 patients were obtained from the Johns Hopkins tumor bank, as approved by the Institutional Review Board, for GAPDH expression analysis. Statistical analysis was performed by using a two-sample t test or Spearman rank correlation coefficient. RESULTS: In vitro, 3-BrPA affected Hep3B cell viability (half maximal inhibitory concentration = 0.15 mmol/L), and GAPDH shRNA suppressed (45.5%) colony formation. In vivo, percutaneous injection of GAPDH antagonists into luc-Hep3B tumors decreased bioluminescence imaging signal and viability (3-BrPA, P < .0001; GAPDH shRNA, P = .03). The 3-BrPA treatment primarily inhibited GAPDH activity (74.5%) compared with its expression (34.3%), whereas GAPDH shRNA inhibited both activity (60.6%) and expression (44.4%). Targeted inhibition of GAPDH by using 3-BrPA or shRNA induced apoptosis. HCC samples from patients demonstrated a strong correlation between GAPDH upregulation and the proto-oncogene c-jun expression (r = 0.543, P = .003). CONCLUSION: Percutaneous injection of GAPDH antagonists induces apoptosis and blocks Hep3B tumor progression, which demonstrates the therapeutic potential of targeting GAPDH in human HCC.

Assessment of tumoricidal efficacy and response to treatment with 18F-FDG PET/CT after intraarterial infusion with the antiglycolytic agent 3-bromopyruvate in the VX2 model of liver tumor.

UNLABELLED: The purpose of this study was to determine the effects of 3-bromopyruvate (3-BrPA) on tumor glucose metabolism as imaged with (18)F-FDG PET/CT at multiple time points after treatment and compare them with those after intraarterial control injections of saline. METHODS: Twenty-three New Zealand White rabbits implanted intrahepatically with VX2 tumors were assigned to 1 of 2 groups: 14 rabbits were assigned to the treatment group (TG) and 9 to the saline control group (SG). All animals were infused with 25 mL of either 1.75 mM 3-BrPA or saline over 1 h via a 2-French catheter, which was secured in the hepatic artery. For PET/CT, the animals were injected with 37 MBq of (18)F-FDG at 1 d before treatment and 2 h, 24 h, and 1 wk after treatment. Tumor size, tumor and liver maximal standardized uptake value (SUV(max)), and tumor-to-background ratios were calculated for all studies. Seven TG and 5 SG animals were sacrificed at 1 wk after treatment for histopathologic analysis. RESULTS: Intense (18)F-FDG uptake was seen in untreated tumors. A significant reduction in tumor SUV(max) was noted in TG animals, when compared with SG animals, at 1 wk after treatment (P = 0.006). The tumor-to-liver background ratio in the TG animals, compared with the SG animals, was significantly reduced as early as 24 h after treatment (P = 0.01) and remained reduced at 1 wk (P = 0.003). Tumor SUV(max) increased from the baseline levels at 7 d in controls (P = 0.05). The histopathologic analysis of explanted livers revealed increased tumor necrosis in all TG samples. There was a significant inverse correlation (r(2) = 0.538, P = 0.005) between the percentage of tumor necrosis on histopathology and tumor SUV(max) on (18)F-FDG PET at 7 d after treatment with 3-BrPA. CONCLUSION: Intraarterial injection of 3-BrPA resulted in markedly decreased (18)F-FDG uptake as imaged by PET/CT and increased tumor necrosis on histopathology at 1 wk after treatment in the VX2 rabbit liver tumor. PET/CT appears to be a useful means to follow antiglycolytic therapy with 3-BrPA.

3-Bromopyruvate induces endoplasmic reticulum stress, overcomes autophagy and causes apoptosis in human HCC cell lines.

BACKGROUND: Autophagy, a cellular response to stress, plays a role in resistance to chemotherapy in cancer cells. Resistance renders systemic chemotherapy generally ineffective against human hepatocellular carcinoma (HCC). Recently, we reported that the pyruvate analog 3-bromopyruvate (3-BrPA) promoted tumor cell death by targeting GAPDH. In continuance, we investigated the intracellular response of two human HCC cell lines (Hep3B and SK-Hep1) that differ in their status of key apoptotic regulators, p53 and Fas. METHODS AND RESULTS: 3-BrPA treatment induced endoplasmic reticulum (ER) stress, translation inhibition and apoptosis based on Western blot and qPCR, pulse labeling, Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and active caspase-3 in both the cell lines. However, electron microscopy revealed that 3-BrPA treated SK-Hep1 cells underwent classical apoptotic cell death while Hep3B cells initially responded with the protective autophagy that failed to prevent eventual apoptosis. CONCLUSION: 3-BrPA treatment promotes apoptosis in human HCC cell lines, irrespective of the intracellular response.

The pyruvic acid analog 3-bromopyruvate interferes with the tetrazolium reagent MTS in the evaluation of cytotoxicity.

3-Bromopyruvate (3BrPA) is a pyruvate analog known for its alkylating property. Recently, several reports have documented the antiglycolytic and anticancer effects of 3BrPA and its potential for therapeutic applications. 3BrPA-mediated cytotoxicity has been evaluated in vitro by various methods including tetrazolium salt (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide)-based assays such as MTT, MTS, and so on. However, growing body of evidences has shown that tetrazolium reagent may interfere with the test compounds. In this study, we investigated whether the tetrazolium reagent interferes with the assessment of 3BrPA cytotoxicity. The results of the tetrazolium-based MTS assay were compared with 3 distinct cell viability detection methods, that is, Trypan Blue staining, ATP depletion, and Annexin V staining in 2 different cell lines, Vx-2 and HepG2. The MTS assay data showed false positive results by indicating increased cell viability at 1 mM and 2 mM 3BrPA whereas the other cell viability assays demonstrated that both Vx-2 and HepG2 cells are not viable at the same treatment conditions. In order to validate the direct interaction of 3BrPA with MTS reagent, we tested cell-free media incubated with different concentrations of 3BrPA. The results of cell-free media showed an increase in absorbance in a dose-dependent manner confirming the interaction of MTS with 3BrPA. Thus, our data clearly demonstrate that 3BrPA interferes with the accuracy of MTS-based cytotoxicity evaluation. Hence, we suggest that employing multiple methods of biochemical as well as morphological cytotoxicity assays is critical to evaluate 3BrPA-mediated cell death.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is pyruvylated during 3-bromopyruvate mediated cancer cell death.

BACKGROUND: The pyruvic acid analog 3-bromopyruvate (3BrPA) is an alkylating agent known to induce cancer cell death by blocking glycolysis. The anti-glycolytic effect of 3BrPA is considered to be the inactivation of glycolytic enzymes. Yet, there is a lack of experimental documentation on the direct interaction of 3BrPA with any of the suggested targets during its anticancer effect. METHODS AND RESULTS: In the current study, using radiolabeled ((14)C) 3BrPA in multiple cancer cell lines, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was identified as the primary intracellular target of 3BrPA, based on two-dimensional (2D) gel electrophoretic autoradiography, mass spectrometry and immunoprecipitation. Furthermore, in vitro enzyme kinetic studies established that 3BrPA has marked affinity to GAPDH. Finally, Annexin V staining and active caspase-3 immunoblotting demonstrated that apoptosis was induced by 3BrPA. CONCLUSION: GAPDH pyruvylation by 3BrPA affects its enzymatic function and is the primary intracellular target in 3BrPA mediated cancer cell death.

Specificity of the anti-glycolytic activity of 3-bromopyruvate confirmed by FDG uptake in a rat model of breast cancer.

PURPOSE: To evaluate the anti-glycolytic effects of 3-BrPA on rats bearing RMT mammary tumors, by determining FDG uptake after intravenous administration of the therapeutic dose. MATERIALS AND METHODS: Sixteen rats bearing RMT tumors were treated either with 15 mM 3-BrPA in 2.5 ml of PBS or with 2.5 ml of PBS. After treatment, all rats received FDG and were sacrificed 1 h later. RESULTS: 3-BrPA treatment significantly decreased FDG uptake in tumors by 77% (p = 0.002). FDG uptake did not significantly decrease in normal tissues after treatment. CONCLUSION: Our study showed that 3-BrPA exhibits a strong anti-glycolytic effect on RMT cells implanted in rats.

Targeting of VX2 rabbit liver tumor by selective delivery of 3-bromopyruvate: a biodistribution and survival study.

The aim of this study was to determine the biodistribution and tumor targeting ability of (14)C-labeled 3-bromopyruvate ([(14)C]3-BrPA) after i.a. and i.v. delivery in the VX2 rabbit model. In addition, we evaluated the effects of [(14)C]3-BrPA on tumor and healthy tissue glucose metabolism by determining (18)F-deoxyglucose (FDG) uptake. Last, we determined the survival benefit of i.a. administered 3-BrPA. In total, 60 rabbits with VX2 liver tumor received either 1.75 mM [(14)C]3-BrPA i.a., 1.75 mM [(14)C]3-BrPA i.v., 20 mM [(14)C]3-BrPA i.v., or 25 ml of phosphate-buffered saline (PBS). All rabbits (with the exception of the 20 mM i.v. group) received FDG 1 h before sacrifice. Next, we compared survival of animals treated with i.a. administered 1.75 mM [(14)C]3-BrPA in 25 ml of PBS (n = 22) with controls (n = 10). After i.a. infusion, tumor uptake of [(14)C]3-BrPA was 1.8 +/- 0.2% percentage of injected dose per gram of tissue (%ID/g), whereas other tissues showed minimal uptake. After i.v. infusion (1.75 mM), tumor uptake of [(14)C]3-BrPA was 0.03 +/- 0.01% ID/g. After i.a. administration of [(14)C]3-BrPA, tumor uptake of FDG was 26 times lower than in controls. After i.v. administration of [(14)C]3-BrPA, there was no significant difference in tumor FDG uptake. Survival analysis showed that rabbits treated with 1.75 mM 3-BrPA survived longer (55 days) than controls (18.6 days). Intra-arterially delivered 3-BrPA has a favorable biodistribution profile, combining a high tumor uptake resulting in blockage of FDG uptake with no effects on healthy tissue. The local control of the liver tumor by 3-BrPA resulted in a significant survival benefit.

Evaluation of different calibrated spherical polyvinyl alcohol microspheres in transcatheter arterial chemoembolization: VX2 tumor model in rabbit liver.

PURPOSE: To assess whether porosity and compressibility of calibrated spherical polyvinyl alcohol (PVA) microspheres affect doxorubicin plasma and tumor concentrations after transcatheter arterial chemoembolization (TACE) in a VX2 rabbit model. MATERIALS AND METHODS: Fifteen rabbits were divided into three groups of five rabbits each. Three different types of calibrated spherical PVA microspheres with variable levels of porosity and compressibility were blindly evaluated. TACE was performed by injecting a mixture of doxorubicin (5 mg) and iodized oil (0.5 mL) followed by injection of the embolic material (0.3-0.5 mL). Plasma concentrations of doxorubicin and doxorubicinol were analyzed 20, 40, 60, and 120 minutes and 2 days after TACE, and liver tissue and tumor doxorubicin concentrations were measured 2 days after TACE. RESULTS: All calibrated spherical PVA microspheres showed similar patterns of plasma doxorubicin and doxorubicinol release and tumor concentration of doxorubicin. There were no significant differences of drug levels in either plasma or tumor in each group (P > .05). CONCLUSIONS: After TACE in a rabbit model of liver cancer, testing of three different types of spherical PVA microspheres with varying degrees of porosity and compressibility showed no significant differences in the plasma doxorubicin release pattern and tumor doxorubicin uptake.

Development of a new orthotopic animal model of metastatic liver cancer in the rabbit VX2 model: effect on metastases after partial hepatectomy, intra-arterial treatment with 3-bromopyruvate and chemoembolization.

AIM: The aim of our study was to compare the influence of partial hepatectomy, intra-arterial treatment with 3-BrPA and TACE on regional and distant metastases. In order to achieve our objective, we tested the feasibility of both resection, intra-arterial therapy with 3-BrPA and TACE of VX2 liver cancer in New Zealand White rabbits. METHODS: VX2 tumors were implanted in the left lateral lobe of the liver of 20 rabbits. Tumors were allowed to grow for 14 days. Rabbits were divided in four groups. Group 1 (n=2) was sacrificed 14 days post implantation. Group 2, 3 and 4 (n=6) underwent left lateral hepatectomy, a 1 h intra-arterial infusion with 3-BrPA and TACE respectively. Animals in each group were further subdivided into three groups of two animals each corresponding to the time-point of sacrifice after the procedure (7, 14 and 21 days respectively). After sacrifice, organs were harvested, fixed and analyzed. RESULTS: Pathologic examination showed lung metastases in all 20 rabbits. Abdominal cavity dissemination was seen in five rabbits in Group 2, two rabbits in Group 3 and all rabbits in Group 4. Kidney metastases were seen in two rabbits treated with TACE. CONCLUSION: The VX2 rabbit model of liver cancer is a suitable model to compare the influence of partial hepatectomy, intra-arterial treatment with 3-BrPA and TACE on tumor recurrence in the form of regional and distant metastases. Our results indicate that intra-arterial delivery of 3-BrPA may result in a favorable metastatic profile when compared to both liver resection and TACE.

Intraarterial therapy with a new potent inhibitor of tumor metabolism (3-bromopyruvate): identification of therapeutic dose and method of injection in an animal model of liver cancer.

PURPOSE: A potent new adenosine triphosphate inhibitor--3-bromopyruvate (3-BrPA)--has been shown to have antitumor effects when injected intraarterially in the hepatic artery of rabbits with VX-2 tumors. The authors performed a stepwise study in rabbits to determine the therapeutic dose and method of delivery of 3-BrPA. MATERIALS AND METHODS: White New Zealand rabbits with VX-2 tumors were used for this study. Eight animals were examined to establish the maximum tolerated dose (2.5 or 5.0 mmol/L of 25-mL 3-BrPA) as a single bolus injection. The 2.5 mmol/L dose was then used to compare three methods of delivery: injection of one bolus, two 12.5-mL serial bolus injections administered 1 hour apart, and continuous infusion of 25 mL for 1 hour. Finally, dose-response analysis was performed by using 10 groups of three animals each, with 1-hour intraarterial infusions of 3-BrPA (25 mL) at incremental doses of 0.25 mmol/L (range, 0.5-2.5 mmol/L) with phosphate buffered saline used for control animals. All animals were sacrificed at 48 hours, and histopathologic analysis was performed. chi2 statistics were used to analyze the data. RESULTS: The maximum tolerated dose of 3-BrPA was 2.5 mmol/L; however, it caused substantial peripheral liver necrosis. These effects were minimized when 3-BrPA was infused over 1 hour. Complete tumor necrosis was identified in all samples with at least 2.0 mmol/L of 3-BrPA. The 1.75 mmol/L concentration was identified as therapeutic because it caused complete tumor apoptosis and minimal toxicity (P < .001). CONCLUSIONS: The results identified both the therapeutic dose (1.75 mmol/L) and the method of infusion (1 hour intraarterial infusion) of 3-BrPA. This potent new treatment may prove to be an effective way of treating liver cancer and may become part of a new class of anticancer drugs based on the inhibition of tumor metabolism.

Ductal access for prevention and therapy of mammary tumors.

In cancer patients and in those at high risk, systemic exposure to agents for therapy or prevention is accompanied by undesirable side effects. We hypothesized that it is possible to prevent and treat breast cancer by introducing anticancer agents into the mammary ductal network. Here, we show the efficacy of intraductally administered anticancer agents 4-hydroxytamoxifen and pegylated liposomal doxorubicin (PLD) in the prevention and treatment of breast cancer using the rat N-methyl-N'-nitrosourea-induced and spontaneous HER-2/neu transgenic mouse (neu-N) models of breast cancer. Intraductal administration of PLD to neu-N mice caused regression of established tumors and prevented tumor development more effectively than i.v. injection (P < 0.0001). Intraductal administration resulted in lower circulating levels of PLD compared with i.v. administration, with no evidence of systemic toxicity or long-term histopathologic changes in the mammary gland. Compared with systemic administration, intraductal injection provides direct access to breast lesions with higher local and lower systemic drug exposure. These studies suggest that this approach has potential for application to prevention and neoadjuvant therapy of early breast cancer.

Very high frequency of hypermethylated genes in breast cancer metastasis to the bone, brain, and lung.

PURPOSE: Most often it is not the primary tumor, but metastasis to distant organs that results in the death of breast cancer patients. To characterize molecular alterations in breast cancer metastasis, we investigated the frequency of hypermethylation of five genes (Cyclin D2, RAR-beta, Twist, RASSF1A, and HIN-1) in metastasis to four common sites: lymph node, bone, brain, and lung. EXPERIMENTAL DESIGN: Methylation-specific PCR for the five genes was performed on DNA extracted from archival paraffin-embedded specimens of paired primary breast cancer and its lymph nodes (LN) metastasis (n = 25 each); in independent samples of metastasis to the bone (n = 12), brain (n = 8), and lung (n = 10); and in normal bone, brain, and lung (n = 22). RESULTS: No hypermethylation was detected in the five genes in the normal host tissues. In paired samples, LN metastasis had a trend of higher prevalence of methylation compared with the primary breast carcinoma for all five genes with significance for HIN-1 (P = 0.04). Compared with the primary breast carcinomas, all five genes had higher methylation frequencies in the bone, brain, and lung metastasis, with HIN-1 and RAR-beta methylation being significantly higher (P < 0.01) in each group. Loss of expression of all five genes correlated, with a few exceptions, to hypermethylation of their promoter sequences in metastatic carcinoma cells microdissected from LNs. CONCLUSION: The frequent presence of hypermethylated genes in locoregional and distant metastasis could render them particularly susceptible to therapy targeted toward gene reactivation combining demethylating agents, histone deacetylase inhibitors, and/or differentiating agents.

Clostridium perfringens enterotoxin elicits rapid and specific cytolysis of breast carcinoma cells mediated through tight junction proteins claudin 3 and 4.

Clostridium perfringens enterotoxin (CPE) induces cytolysis very rapidly through binding to its receptors, the tight junction proteins CLDN 3 and 4. In this study, we investigated CLDN 3 and 4 expression in breast cancer and tested the potential of CPE-mediated therapy. CLDN 3 and 4 proteins were detected in all primary breast carcinomas tested (n = 21) and, compared to normal mammary epithelium, were overexpressed in approximately 62% and 26%, respectively. Treatment of breast cancer cell lines in culture with CPE resulted in rapid and dose-dependent cytolysis exclusively in cells that expressed CLDN 3 and 4. Intratumoral CPE treatment of xenografts of T47D breast cancer cells in immunodeficient mice resulted in a significant reduction in tumor volume (P = 0.007), with accompanying necrosis. Necrotic reactions were also seen in three freshly resected primary breast carcinoma samples treated with CPE for 12 hours, while isolated primary breast carcinoma cells underwent rapid and complete cytolysis within 1 hour. Thus, expression of CLDN 3 and 4 sensitizes primary breast carcinomas to CPE-mediated cytolysis and emphasizes the potential of CPE in breast cancer therapy.