Tumor-bearing Hamsters Research Articles

The Therapeutic Effect of Antitumor Drugs Erufosine and Doxorubicin on the Metastatic Process in the Testes of Hamsters with Graffi Myeloid Tumor. Morphometric and Histological Studies

Aim. The goal of the current study is directed to investigate the therapeutic effect of erufosine (ЕРС3) alone, as well as in combination with doxorubicin (DOX) on the development of metastases in the testes in an experimental model of transplantable Graffi myeloid tumor (GMT) in hamsters.
 Materials & Methods. Experimental in vivo model of GMT in Golden Syrian hamsters was used. Animals were inoculated subcutaneously with live virus-transformed malignant cells. Testes from male tumor-bearing hamsters (TBHs), treated and non-treated with the antitumor agent erufosine alone or in combination with DOX, as well as untreated healthy controls, were subjected to morphometric and histological assays on the testicular architecture to evaluate potential antitumor/antimetastatic effects in in vivo conditions.
 Results. The results showed no changes in blood vessels and morphology (impaired spermatogenesis and/or metastatic changes) of the testicular tissue in TBHs treated with antitumor agents (alone or in combination) compared to control healthy animals. In contrast, in the testes of TBHs without therapy, impaired spermatogenesis and foci of metastases, as well as significant changes in testicular blood vessels were found.
 Conclusion. The data obtained demonstrated an antitumor/antimetastatic effect of EPC3 in the testes of hamsters in the experimental GMT model.

Enhancement in the Therapeutic Efficacy of In Vivo BNCT Mediated by GB-10 with Electroporation in a Model of Oral Cancer.

Boron neutron capture therapy (BNCT) combines preferential tumor uptake of 10B compounds and neutron irradiation. Electroporation induces an increase in the permeability of the cell membrane. We previously demonstrated the optimization of boron biodistribution and microdistribution employing electroporation (EP) and decahydrodecaborate (GB-10) as the boron carrier in a hamster cheek pouch oral cancer model. The aim of the present study was to evaluate if EP could improve tumor control without enhancing the radiotoxicity of BNCT in vivo mediated by GB-10 with EP 10 min after GB-10 administration. Following cancerization, tumor-bearing hamster cheek pouches were treated with GB-10/BNCT or GB-10/BNCT + EP. Irradiations were carried out at the RA-3 Reactor. The tumor response and degree of mucositis in precancerous tissue surrounding tumors were evaluated for one month post-BNCT. The overall tumor response (partial remission (PR) + complete remission (CR)) increased significantly for protocol GB-10/BNCT + EP (92%) vs. GB-10/BNCT (48%). A statistically significant increase in the CR was observed for protocol GB-10/BNCT + EP (46%) vs. GB-10/BNCT (6%). For both protocols, the radiotoxicity (mucositis) was reversible and slight/moderate. Based on these results, we concluded that electroporation improved the therapeutic efficacy of GB-10/BNCT in vivo in the hamster cheek pouch oral cancer model without increasing the radiotoxicity.

An immune-competent, replication-permissive Syrian Hamster glioma model for evaluating Delta-24-RGD oncolytic adenovirus.

Oncolytic adenoviruses are promising new treatments against solid tumors, particularly for glioblastoma (GBM), and preclinical models are required to evaluate the mechanisms of efficacy. However, due to the species selectivity of adenovirus, there is currently no single animal model that supports viral replication, tumor oncolysis, and a virus-mediated immune response. To address this gap, we took advantage of the Syrian hamster to develop the first intracranial glioma model that is both adenovirus replication-permissive and immunocompetent. We generated hamster glioma stem-like cells (hamGSCs) by transforming hamster neural stem cells with hTERT, simian virus 40 large T antigen, and h-RasV12. Using a guide-screw system, we generated an intracranial tumor model in the hamster. The efficacy of the oncolytic adenovirus Delta-24-RGD was assessed by survival studies, and tumor-infiltrating lymphocytes (TILs) were evaluated by flow cytometry. In vitro, hamGSCs supported viral replication and were susceptible to Delta-24-RGD mediated cell death. In vivo, hamGSCs consistently developed into highly proliferative tumors resembling high-grade glioma. Flow cytometric analysis of hamster gliomas revealed significantly increased T-cell infiltration in Delta-24-RGD infected tumors, indicative of immune activation. Treating tumor-bearing hamsters with Delta-24-RGD led to significantly increased survival compared to hamsters treated with phosphate buffered saline (PBS). This adenovirus-permissive, immunocompetent hamster glioma model overcomes the limitations of previous model systems and provides a novel platform to study the interactions between tumor cells, the host immune system, and oncolytic adenoviral therapy; understanding of which will be critical to implementing oncolytic adenovirus in the clinic.

Protective and Antitumor Effects of Oxidal and Pyrucet in Hamsters with Experimental Graffi Tumor

The use of combination drug therapy instead of monotherapy is a new positive and promising approach in the treatment of cancer. Oxidal® and Pyrucet® are food supplements containing Methylene blue (USP), Caffeine (USP), Salicylic acid (USP) and Ethyl Acetoacetate and Ethyl Pyruvate respectively. The therapeutic significance of each of these compounds (their derivatives) is well established, but no data are available on their combined action in in vivo experimental tumor models.
 The aim of the present study was to investigate the in vivo protective effect of mono- and combined experimental therapy with dietary supplements Oxidal® and Pyrucet® in the Graffi myeloid tumor model in hamsters. For this purpose, the two drugs were administered alone or in combination in two treatment regimens - prophylactic (before) and therapeutic (simultaneously) with the transplantation of Graffi tumor cells. The protective effect was determined by the biometric parameters of tumor growth (transplantability, tumor size, mortality, mean survival time, survival rate) recorded during the experiment. The results showed a favorable effect of both drugs, administered alone or in combination, before and simultaneously with the transplantation of tumor cells on the appearance and development of Graffi tumor in hamsters. About 2-fold lower transplantability, prolongation of the latency period by 7 days, inhibition of tumor growth till 30thday of experiments, reduced mortality and increased individual and overall survival time between 7 to 10 days were observed in the Graffi tumor-bearing hamsters with experimental therapy compared to control-Graffi tumor-bearing hamsters, without therapy. The obtained data revealed that Oxidal® and Pyrucet® could be a promising candidate for the treatment of tumor diseases.

TMOD-16. A NOVEL ADENOVIRAL-PERMISSIVE, IMMUNOCOMPETENT HAMSTER GLIOMA MODEL TO EVALUATE ONCOLYTIC ADENOVIRAL THERAPY

Abstract Oncolytic adenoviruses, including Delta-24-RGD, target tumors by direct tumor cell oncolysis and by activation of an anti-tumor immune response. Due to the species selectivity of oncolytic adenoviruses, there is currently no single preclinical animal model of glioma that supports viral replication, tumor oncolysis, and virus-mediated immune responses. To address this gap, we took advantage of the Syrian hamster to develop the first glioma model that is both adenovirus replication-permissive and immunocompetent. Hamster glioma stem-like cells (GSCs), transformed by forced expression of hTERT, SV40 large T antigen, and h-RasV12, reproducibly form intracranial tumors in hamsters. In vitro, electron microscopy and cytopathic effect assays demonstrated that hamster GSCs supported viral replication and were susceptible to Delta-24-RGD-mediated cell death. In vivo, hamster GSCs consistently developed into highly proliferative tumors resembling high-grade gliomas. Following intratumoral delivery of Delta-24-RGD, immunohistochemistry for viral proteins demonstrated viral infectivity and replication in hamster gliomas. Flow cytometry revealed increased T cell infiltration in Delta-24-RGD-infected tumors. Delta-24-RGD treatment of tumor-bearing hamsters led to significantly increased survival compared with hamsters treated with PBS. Using this model, we evaluated the effects of corticosteroid-mediated immunosuppression on Delta-24-RGD efficacy. Dexamethasone treatment significantly decreased peripheral blood lymphocytes, decreased tumor-infiltrating lymphocytes, and suppressed the levels of serum anti-adenovirus antibodies. Dexamethasone reduced the number of long-term survivors and decreased the median survival (50 days for Delta-24-RGD + dexamethasone vs undetermined for Delta-24-RGD alone). In summary, we have developed the first adenovirus-permissive, immunocompetent hamster glioma model, addressing a critical need for a model in which to study the role of direct oncolysis in driving immune mediated viral clearance versus driving an antiglioma immune response. Understanding these mechanisms is critical to optimizing the success of oncolytic adenoviral therapy in the clinic.

Abstract 10: Sclareol induces apoptosis and inhibits notch signaling in hamster oral carcinogenesis

Abstract The Notch signaling pathway is an evolutionarily conserved cell signaling pathway. It plays a central role in cell fate decisions and differentiation. The bioavailability of sclareol has been widely studied due to its anti-carcinogenic and antioxidant effects. However, chemo preventive effects of sclareol on notch signaling in 7, 12-dimethylbenz [a] anthracene (DMBA) induced hamster buccal pouch(HBP) carcinogenesis remain to be fully elucidated. In the present study, tumors were induced by applying 0.5% DMBA topically to HBP thrice a week for 14 weeks and sclareol was orally administered at a dose of 20mg/kg body weight on alternate days of DMBA painting. We analyzed expression of Notch signaling in DMBA induced oral squamous cell carcinoma (OSCC) in experimental oral carcinogenesis and inhibition of notch signaling by sclareol. This study thus observed up regulation of Notch1, Notch2, Jagged1, Hes1 and Hey1 in DMBA alone induced hamsters. Furthermore, oral administration of sclareol led to reduced Notch1, Notch2 activation and expression of Jagged-1 and its downstream targets of Hes-1 and Hey-1 in tumor bearing hamsters. In addition, sclareol treatment increased pro-apoptotic and decreased anti-apoptotic proteins survival indicating apoptosis through activation of caspase 3, and promoting cell death by dysregulation of cyclin D1 levels in tumor bearing hamsters. Immunohistochemical examination showed that Notch intracellular domain accumulates in the nucleus of cells in DMBA induced hamster buccal pouch carcinogenesis, and Jagged1 was found to be dysregulated in sclareol treated tumor animals. In conclusion, the results provide an important new insight of Notch signaling pathway for a potential therapeutic target for oral cancer. Citation Format: Aiyavu Chinnaiyan, Anandhi Nallu, Suresh Kathiresan. Sclareol induces apoptosis and inhibits notch signaling in hamster oral carcinogenesis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 10.

Macrophage migration inhibitory factor of Syrian golden hamster shares structural and functional similarity with human counterpart and promotes pancreatic cancer

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that increasingly is being studied in cancers and inflammatory diseases. Though murine models have been instrumental in understanding the functional role of MIF in different pathological conditions, the information obtained from these models is biased towards a specific species. In experimental science, results obtained from multiple clinically relevant animal models always provide convincing data that might recapitulate in humans. Syrian golden hamster (Mesocricetus auratus), is a clinically relevant animal model for multiple human diseases. Hence, the major objectives of this study were to characterize the structure and function of Mesocricetus auratus MIF (MaMIF) and finally evaluate its effect on pancreatic tumor growth in vivo. Initially, the recombinant MaMIF was cloned, expressed and purified in a bacterial expression system. The MaMIF primary sequence, biochemical properties, and crystal structure analysis showed greater similarity with human MIF. The crystal structure of MaMIF illustrates that it forms a homotrimer as known in human and mouse. However, MaMIF exhibits some minor structural variations when compared to human and mouse MIF. The in vitro functional studies show that MaMIF has tautomerase activity and enhances activation and migration of hamster peripheral blood mononuclear cells (PBMCs). Interestingly, injection of MaMIF into HapT1 pancreatic tumor-bearing hamsters significantly enhanced the tumor growth and tumor-associated angiogenesis. Together, the current study shows a structural and functional similarity between the hamster and human MIF. Moreover, it has demonstrated that a high level of circulating MIF originating from non-tumor cells might also promote pancreatic tumor growth in vivo.

Beneficial Effects of Drossinakis Bio-influence (With Infrared Thermal and Electromagnetic Fields) on the Development of Experimental Graffi Myeloid Tumors in Hamsters. Hematological Studies

The aim of the present experiments was to study the effect of bioinfluence - Infrared thermal field (ITF) and electromagnetic fields (e.m. fields) on the progression of experimental tumor – Graffi myeloid tumor in hamsters Spectral analysis methods called Non-equilibrium spectrum (NES) and Differential non-equilibrium spectrum (DNES) for 1% solutions of blood serum from hamsters with cancer and healthy hamsters were investigated. Drossinakis has a beneficial effect on the Graffi tumor-bearing hamsters. Results are obtained with the DNES method - compared to the control serum samples of hamsters with cancer and healthy hamsters. The spectrum was obtained in the range (-0.0937 eV; 13.23 μm; 755 cm -1 ) - (-0.1387 eV; 8.95; μm; 1117 cm -1 ). The average energy (∆E H...O ) of hydrogen Н…O-bonds among individual molecules H 2 O after treatment of Drossinakis was measured by NES- and DNES-methods. The result ∆E=-0.0071±0.0011 eV is according control serum samples of hamsters with cancer and ∆E=-0.0035±0.0011 eV is for healthy ones. These results suggest the restructuring of ∆E H...O values among H 2 O molecules with a statistically reliable increase of local extremums in DNES-spectra. Local extremum was obtained at (-0.1212) eV, which is an indicator of anti-inflammatory effect. Another local extremum was obtained at (-0.1387) eV, which is an indicator of the tumor-development inhibition at the cellular- and the molecular level. The beneficial effects of Drossinakis are characterized as the anti-inflammatory, anti-oxidant, anti-cancer, anti-stroke,etc. This article deals with the review of the basic biophysical-, biochemical- and biological processes - bio-influenced of Drossinakis. In this sense, the experimental research of Toshkova and co-authors has shown increased life span of the tumor-bearing hamsters, bio-influenced by Drossinakis. There are new analyses from hematological studies from Zvetkova. Keywords : Christos Drossinakis - bioinfluence, Infrared thermal field (ITF), Electromagnetic fields, Experimental myeloid tumor of Graffi , hematological studies - erythrocytes DOI : 10.7176/JMPB/54-02 Publication date : April 30 th 2019

Chemopreventive effect of syringic acid on 7,12-dimethylbenz(a)anthracene induced hamster buccal pouch carcinogenesis

Oral squamous cell carcinoma is most prevalent and refractory cancers worldwide. Recently, chemoprevention could be a promising approach in developing countries. The present study investigates the mechanism of syringic acid (SA), a phenolic constituent of plant Alpiniacalcarata Roscoe, and their leaves are used as traditional Indian Ayurveda medicines, mediated chemoprevention on 7,12-dimethylbenz(a)anthracene (DMBA)-induced hamster buccal pouch carcinogenesis (HBPC). Lipid peroxidation and antioxidants were measured in the plasma and buccal tissues in experimental hamsters. Modulating effect of SA on the expression pattern of PCNA, Cyclin D1, and mutant p53 markers was used for immunoexpression and western blotting analysis. In the present study, 100% tumor formation with marked abnormalities in the biochemical parameters of lipid peroxidation and antioxidants through up-regulation of molecular markers like PCNA, Cyclin D1, and mutant p53 was accompanied with tumor-bearing hamsters. Oral administration of SA at the doses of 50 and 100 mg/kg body weight (bw) to DMBA-treated hamsters significantly inhibited adverse changes in the biochemical parameters of the plasma and buccal mucosal tissues and also down-regulation of molecular marker expression (PCNA, Cyclin D1, and mutant p53). The present study thus suggests that SA has potent anti-lipid peroxidative, antioxidant, anti-cell proliferative, and apoptosis-inducing properties during DMBA-induced HBPC.

Syngeneic Syrian hamster tumors feature tumor-infiltrating lymphocytes allowing adoptive cell therapy enhanced by oncolytic adenovirus in a replication permissive setting

ABSTRACTAdoptive transfer of tumor-infiltrating lymphocytes (TIL) has shown promising yet sometimes suboptimal results in clinical trials for advanced cancer, underscoring the need for approaches improving efficacy and safety. Six implantable syngeneic tumor cell lines of the Syrian hamster were used to initiate TIL cultures. TIL generated from tumor fragments cultured in human interleukin-2 (IL-2) for 10 d were adoptively transferred into tumor-bearing hamsters with concomitant intratumoral injections of oncolytic adenovirus (Ad5-D24) for the assessment of antitumor efficacy. Pancreatic cancer (HapT1) and melanoma (RPMI 1846) TIL exhibited potent and tumor-specific cytotoxicity in effector-to-target (E/T) assays. MHC Class I blocking abrogated the cell killing of RPMI 1846 TIL, indicating cytotoxic CD8+ T-cell activity. When TIL were combined with Ad5-D24 in vitro, HapT1 tumor cell killing was significantly enhanced over single agents. In vivo, the intratumoral administration of HapT1 TIL and Ad5-D24 resulted in improved tumor growth control compared with either treatment alone. Additionally, splenocytes derived from animals treated with the combination of Ad5-D24 and TIL killed autologous tumor cells more efficiently than monotherapy-derived splenocytes, suggesting that systemic antitumor immunity was induced. For the first time, TIL of the Syrian hamster have been cultured, characterized and used therapeutically together with oncolytic adenovirus for enhancing the efficacy of TIL therapy. Our results support human translation of oncolytic adenovirus as an enabling technology for adoptive T-cell therapy of solid tumors.

Antitumor activity of C-phycocyanin from Arthronema africanum (Cyanophyceae)

ABSTRACT Pure C-phycocyanin (C-PC) was isolated from Arthronema africanum to evaluate its potential antitumor effects in vivo and in vitro. Experimental myeloid Graffi tumor in hamsters was used as a model. The cell proliferation assay showed that C-PC treatment, at concentration of 100 µg mL -1 for 24 h, significantly inhibited the growth of Graffi tumor cells (51.4% viability). Agarose gel electrophoresis of the genomic DNA of treated cells displayed time- and concentration-dependent fragmentation pattern, typical for apoptosis. Apoptotic process was related to the increase in cellular manganese and copper/zinc superoxide dismutases and glutathione reductase activities, coupled with a low catalase activity. In vivo C-PC administration (5.0 mg kg -1 body weight) suppressed the tumor transplantability and growth, while the mean survival time of the tumor-bearing hamsters was increased. The results revealed promising antitumor activities of A. africanum C-PC and suggested the potential of this natural biliprotein pigment for future pharmacological and medical applications. The study provided new data on the mechanism of the C-PC-induced apoptosis in which the imbalance of antioxidant enzymes that favoured hydrogen peroxide accumulation might play a leading role. Key words: Antitumor activity, Arthronema africanum , In vivo , In vitro , C-pycocyanin, Myeloid Graffi tumor

Biodistribution of sodium borocaptate (BSH) for boron neutron capture therapy (BNCT) in an oral cancer model

Boron neutron capture therapy (BNCT) is based on selective accumulation of ¹⁰B carriers in tumor followed by neutron irradiation. We previously proved the therapeutic success of BNCT mediated by the boron compounds boronophenylalanine and sodium decahydrodecaborate (GB-10) in the hamster cheek pouch oral cancer model. Based on the clinical relevance of the boron carrier sodium borocaptate (BSH) and the knowledge that the most effective way to optimize BNCT is to improve tumor boron targeting, the specific aim of this study was to perform biodistribution studies of BSH in the hamster cheek pouch oral cancer model and evaluate the feasibility of BNCT mediated by BSH at nuclear reactor RA-3. The general aim of these studies is to contribute to the knowledge of BNCT radiobiology and optimize BNCT for head and neck cancer. Sodium borocaptate (50 mg ¹⁰B/kg) was administered to tumor-bearing hamsters. Groups of 3-5 animals were killed humanely at nine time-points, 3-12 h post-administration. Samples of blood, tumor, precancerous pouch tissue, normal pouch tissue and other clinically relevant normal tissues were processed for boron measurement by optic emission spectroscopy. Tumor boron concentration peaked to therapeutically useful boron concentration values of 24-35 ppm. The boron concentration ratio tumor/normal pouch tissue ranged from 1.1 to 1.8. Pharmacokinetic curves showed that the optimum interval between BSH administration and neutron irradiation was 7-11 h. It is concluded that BNCT mediated by BSH at nuclear reactor RA-3 would be feasible.

Saffron Reduction of 7,12-Dimethylbenz[a]anthracene-induced Hamster Buccal Pouch Carcinogenesis

Our aim was to investigate the chemopreventive potential of saffron in DMBA-induced hamster buccal pouch carcinogenesis. Assessment was by monitoring the percentage of tumor bearing hamsters, tumor size as well as the status of detoxification agents, lipid peroxidation and antioxidants. Oral squamous cell carcinomas were induced in the buccal pouch of Syrian golden hamsters by painting them with 0.5% DMBA in liquid paraffin three times a week for 14 weeks. We observed 100% oral tumor formation with severe histopathological abnormalities in all the hamsters treated with DMBA alone, activities of phase I and phase II detoxification enzymes, lipid peroxidation and antioxidants being significantly altered. Though oral administration of saffron completely prevented the formation of tumors, we noticed severe hyperplasia and dysplasia in hamsters treated with DMBA, suggesting that tumors might eventually develop. Oral administration of saffron return detoxification enzymes, lipid peroxidation and antioxidants to normal ranges. The chemopreventive potential of saffron thus is likely due to antioxidant properties and modulating effects on detoxification in favour of the excretion of carcinogenic metabolites during DMBA-induced hamster buccal pouch carcinogenesis.

Anti-Cell Proliferative Efficacy of Ferulic Acid Against 7, 12-dimethylbenz(a) Anthracene Induced Hamster Buccal Pouch Carcinogenesis

The present study was designed to explore the anti-cell proliferative efficacy of ferulic acid by analysing the expression pattern of cell proliferative markers, proliferating cellular nuclear antigen (PCNA) and cyclin D1, in the buccal mucosa of golden Syrian hamsters treated with 7,12-dimethylbenz(a)anthracene (DMBA). Oral squamous cell carcinomas developed in the buccal pouch of hamsters using topical application of 0.5% DMBA three times a week for 14 weeks. Immunohistochemical (PCNA) and RT-PCR (Cyclin D1) analysis revealed over expression of PCNA and cyclin D1 in the buccal mucosa of hamsters treated with DMBA alone (tumor bearing hamsters). Oral administration of ferulic acid at a dose of 40 mg/kg bw to hamsters treated with DMBA not only completely prevented the tumor formation but also down regulated the expression of PCNA and cyclin D1. The results of the present study thus suggests that ferulic acid might have inhibited tumor formation in the buccal mucosa of hamsters treated with DMBA through its anti-cell proliferative potential as evidenced by decreased expression of PCNA and cyclin D1.

Proapoptotic, Anti-Cell Proliferative, Anti-Inflammatory And Antiangiogenic Potential Of Carnosic Acid During 7,12 Dimethylbenz[A]Anthracene-Induced Hamster Buccal Pouch Carcinogenesis

The present study has investigated the modulating effect of carnosic acid on the expression pattern of cell proliferative (proliferating cell nuclear antigen (PCNA) cyclin D1 and a transcription factor c-fos), apoptotic (p53, Bcl-2, Bax caspase -3 and 9), inflammatory (Nuclear factor kappa B (NFκB) and cyclooxygenase-2 (COX- 2) and angiogenic (vascular endothelial growth factor (VEGF) markers during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch carcinogenesis. Oral tumors were developed in the hamsters buccal pouches by painting with 0.5% DMBA in liquid paraffin three times a week for 14 weeks. Hundred per cent tumour formation (well-differentiated squamous cell carcinoma) accompanied by deregulation in the above mentioned molecular markers was noticed in hamsters treated with DMBA alone (tumour bearing hamsters). Oral administration of carnosic acid at dose of 10mg/kg bw to hamsters treated with DMBA not only completely prevented the tumour formation, but also corrected the abnormalities in the expression pattern of molecular markers. The present study suggests that carnosic acid might have inhibited the tumour formation by exerting anti-cell-proliferative, anti-inflammatory, anti-angiogenic and apoptotic potential during DMBA-induced hamster buccal pouch carcinogenesis.

Tumor Blood Vessel “Normalization” Improves the Therapeutic Efficacy of Boron Neutron Capture Therapy (BNCT) in Experimental Oral Cancer

We previously demonstrated the efficacy of BNCT mediated by boronophenylalanine (BPA) to treat tumors in a hamster cheek pouch model of oral cancer with no normal tissue radiotoxicity and moderate, albeit reversible, mucositis in precancerous tissue around treated tumors. It is known that boron targeting of the largest possible proportion of tumor cells contributes to the success of BNCT and that tumor blood vessel normalization improves drug delivery to the tumor. Within this context, the aim of the present study was to evaluate the effect of blood vessel normalization on the therapeutic efficacy and potential radiotoxicity of BNCT in the hamster cheek pouch model of oral cancer. Blood vessel normalization was induced by two doses of thalidomide in tumor-bearing hamsters on 2 consecutive days. All studies in thalidomide-treated animals were performed 48 h after the first dose of thalidomide, previously established as the window of normalization. Biodistribution studies were performed with BPA at a dose of 15.5 mg (10)B/kg in thalidomide-treated (Th+) and untreated (Th-) tumor-bearing hamsters. The effect of blood vessel normalization prior to BPA administration on the efficacy of BNCT was assessed in in vivo BNCT studies at the RA-3 Nuclear Reactor in tumor-bearing hamsters. Group I was treated with BPA-BNCT after treatment with thalidomide (Th+ BPA-BNCT). Group II was treated with BPA-BNCT alone (Th- BPA-BNCT). Group III was treated with the beam only after treatment with thalidomide (Th+ BO), and Group IV was treated with the beam only (Th- BO). Groups I and II were given the same dose of BPA (15.5 mg (10)B/kg), and all groups (I-IV) were exposed to the same neutron fluence. Two additional groups were treated with the beam only at a higher dose to exacerbate mucositis in precancerous tissue and to explore the potential direct protective effect of thalidomide on radiation-induced mucositis in a scenario of more severe toxicity, i.e. Group V (Th+ hdBO) and Group VI (Th- hdBO). The animals were followed for 28 days. Biodistribution studies revealed no statistically significant differences in gross boron content between Th+ and Th- animals. Overall tumor control (complete response + partial response) at 28 days post-treatment was significantly higher for Group I (Th+ BPA-BNCT) than for Group II (Th- BPA-BNCT): 84 ± 3% compared to 67 ± 5%. Pretreatment with thalidomide did not induce statistically significant changes in overall tumor control induced by the beam only, i.e. 15 ± 5% in Group III (Th+ BO) and 18 ± 5% in Group IV (Th- BO), or in overall tumor control induced by the high-dose beam only, i.e. 60 ± 7% in Group V (Th+ hdBO) and 47 ± 10% in Group VI (Th- hdBO). BPA-BNCT alone (Group II) induced mucositis in precancerous tissue that reached Grades 3-4 in 80% of the animals, whereas pretreatment with thalidomide (Group I) prevented mucositis Grades 3 and 4 completely. Beam-only Group III (Th+ BO) exhibited only Grade 1 mucositis in precancerous tissue, whereas 17% of the animals in beam-only Group IV (Th- BO) reached Grade 2 mucositis. High-dose beam-only group V (Th+ hdBO) exhibited only Grade 2 mucositis, whereas high-dose beam-only group VI (Th- hdBO) reached Grade 3 mucositis in 83% of the animals. In all cases mucositis in precancerous tissue was reversible. No normal tissue radiotoxicity was observed with any of the protocols. Pretreatment with thalidomide enhanced the therapeutic efficacy of BNCT and reduced precancerous tissue toxicity.

Inhibitory effect of vitamin D-binding protein-derived macrophage activating factor on DMBA-induced hamster cheek pouch carcinogenesis and its derived carcinoma cell line.

This study investigated the inhibitory effect of vitamin D-binding protein-derived macrophage-activating factor (GcMAF) on carcinogenesis and tumor growth, using a 9,10-dimethyl-1,2-benzanthracene (DMBA)-induced hamster cheek pouch carcinogenesis model, as well as the cytocidal effect of activated macrophages against HCPC-1, a cell line established from DMBA-induced cheek pouch carcinoma. DMBA application induced squamous cell carcinoma in all 15 hamsters of the control group at approximately 10 weeks, and all 15 hamsters died of tumor burden within 20 weeks. By contrast, 2 out of the 14 hamsters with GcMAF administration did not develop tumors and the remaining 12 hamsters showed a significant delay of tumor development for approximately 3.5 weeks. The growth of tumors formed was significantly suppressed and none of the hamsters died within the 20 weeks during which they were observed. When GcMAF administration was stopped at the 13th week of the experiment in 4 out of the 14 hamsters in the GcMAF-treated group, tumor growth was promoted, but none of the mice died within the 20-week period. On the other hand, when GcMAF administration was commenced after the 13th week in 5 out of the 15 hamsters in the control group, tumor growth was slightly suppressed and all 15 hamsters died of tumor burden. However, the mean survival time was significantly extended. GcMAF treatment activated peritoneal macrophages in vitro and in vivo, and these activated macrophages exhibited a marked cytocidal effect on HCPC-1 cells. Furthermore, the cytocidal effect of activated macrophages was enhanced by the addition of tumor-bearing hamster serum. These findings indicated that GcMAF possesses an inhibitory effect on tumor development and growth in a DMBA-induced hamster cheek pouch carcinogenesis model.

Evaluation of chemopreventive effects of Thymoquinone on cell surface glycoconjugates and cytokeratin expression during DMBA induced hamster buccal pouch carcinogenesis

The present study aimed to investigate the membrane stabilizing effect of Thymoquinone (TQ) on cell surface glycoconjugates and cytokeratin expression against DMBA induced hamster buccal pouch carcinogenesis. 0.5% DMBA painting (three times per week) in hamster buccal pouches for 14 weeks resulted in the formation of well developed oral squamous cell carcinoma. We observed 100% tumor formation with marked abnormalities of glycoconjugates status in tumor bearing hamsters as compared to control animals. Oral administration of TQ at a dose of 30 mg/kg body weight, to DMBA painted hamsters on alternate days for 14 weeks, reduced the tumor formation as well as protected the levels of cell surface glycoconjugates in DMBA painted hamsters. The present study thus suggests that TQ has potent chemopreventive efficacy as well as protected the abnormalities on cell surface glycoconjugates during DMBA induced hamster buccal pouch carcinogenesis.

Protective effect of Withaferin-A on micronucleus frequency and detoxication agents during experimental oral carcinogenesis

Our aim was to investigate the effect of Withaferin-A on bone marrow micronucleus frequency and buccal mucosa detoxication agents during 7, 12-dimethylbenz[a]anthracene (DMBA) induced hamster buccal pouch carcinogenesis. Oral squamous cell carcinoma was developed in hamsters' buccal pouches by painting 0.5% DMBA in liquid paraffin, three times per week for 14 weeks. We observed 100% tumor formation in DMBA painted hamsters. Elevated frequency of bone marrow micronucleated polychromatic erythrocytes (MnPCEs) and decrease in buccal mucosa phase II detoxication agents were noticed in tumor bearing hamsters. Oral administration of Withaferin-A significantly reduced the micronucleus frequency and brought back the status of phase II detoxication agents in DMBA painted hamsters. Our study thus demonstrated the protective effect of Withaferin-A on DMBA-induced micronucleus frequency in the bone marrow of golden Syrian hamsters. Also, Withaferin-A maintained the status of buccal mucosa detoxication agents during DMBA-induced hamster buccal pouch carcinogenesis.

Dosimetry and radiobiology at the new RA-3 reactor boron neutron capture therapy (BNCT) facility: Application to the treatment of experimental oral cancer

The National Atomic Energy Commission of Argentina (CNEA) constructed a novel thermal neutron source for use in boron neutron capture therapy (BNCT) applications at the RA-3 research reactor facility located in Buenos Aires. The aim of the present study was to perform a dosimetric characterization of the facility and undertake radiobiological studies of BNCT in an experimental model of oral cancer in the hamster cheek pouch. The free-field thermal flux was 7.1×10 9 n cm −2 s −1 and the fast neutron flux was 2.5×10 6 n cm −2 s −1, indicating a very well-thermalized neutron field with negligible fast neutron dose. For radiobiological studies it was necessary to shield the body of the hamster from the neutron flux while exposing the everted cheek pouch bearing the tumors. To that end we developed a lithium (enriched to 95% in 6Li) carbonate enclosure. Groups of tumor-bearing hamsters were submitted to BPA-BNCT, GB-10-BNCT, (GB-10+BPA)-BNCT or beam only treatments. Normal (non-cancerized) hamsters were treated similarly to evaluate normal tissue radiotoxicity. The total physical dose delivered to tumor with the BNCT treatments ranged from 6 to 8.5 Gy. Tumor control at 30 days ranged from 73% to 85%, with no normal tissue radiotoxicity. Significant but reversible mucositis in precancerous tissue surrounding tumors was associated to BPA-BNCT. The therapeutic success of different BNCT protocols in treating experimental oral cancer at this novel facility was unequivocally demonstrated.