Rabbit VX2 Carcinoma Research Articles

Experimental study on the role of osteoclasts and free radicals in the mandibular invasion of VX2 carcinoma in Japanese white rabbits

Oxygen-derived free radicals are stimulators of bone resorption in vitro and in vivo. We hypothesized that oxygen-derived free radicals or reactive oxygen species (ROS) generated around bone matrix invaded by cancer cells might be associated with the activation or formation of osteoclasts in bone metastasis, and thus the administration of an ROS scavenger or a free-radical scavenger might control osteoclastic bone destruction in tumor metastasis. We examined the ability of VX2 carcinoma cells to generate superoxide anion (O 2 −) as well as the effects of the O 2 − scavenger superoxide dismutase (SOD) and the hydrogen peroxide (H 2O 2) scavenger catalase (CAT) on the activation and formation of osteoclasts in VX2 carcinoma tissue of rabbits. VX2 carcinoma cells generated more O 2 − than tartrate-resistant acid phosphatase-positive (TRAP+) cells. The TRAP activity from TRAP+ cells in the presence of VX2 carcinoma cells was higher than that from TRAP+ cells in the absence of the carcinoma cells. The addition of SOD but not of CAT into the incubation medium inhibited the TRAP activity from TRAP+ cells in the presence or absence of VX2 carcinoma cells. Similar inhibitory effects were also observed with SOD plus CAT on TRAP+ cells in the presence or absence of carcinoma cells. Intravenous administration of SOD and SOD plus CAT, but not of CAT, caused a decrease in the number of osteoclasts in mandibles implanted with VX2 carcinoma cells, and showed a predominant occupation by osteoclasts with poorly developed ruffled borders in lesions of bone resorption. In contrast, the administration of CAT, but not of SOD and SOD plus CAT, decreased the more mature forms of osteoclasts in implanted mandibles. From the results obtained, it is suggested that O 2 − may stimulate bone resorption by increasing the activity and number of osteoclasts, and H 2O 2 may stimulate resorption by enhancing the formation of mature osteoclasts in tumor metastasis. The administration of some ROS or free-radical scavengers to patients with cancer may provide a defense against bone destruction in bone metastatic lesions.

Perilesional interleukin-2 in the VX-2 carcinoma in rabbits: A preliminary investigation

Immune system amplification by perilesional injection of interleukin-2 is a promising adjuvant approach for treating squamous cell carcinoma of the head and neck. A pilot study was designed to develop an animal model bearing squamous cell carcinoma in which to test the efficacy of perilesional interleukin-2. Rabbits were inoculated intramuscularly with the papilloma virus - induced squamous carcinoma VX-2 cell line. Tumor regression and host lymphatic response after perilesional interleukin-2 were measured. Variable responses were found. Growth of tumor cells implanted from cell culture was rapid in most animals. Tumor growth was prevented in animals receiving 10,000 units of interleukin-2 per injection initiated 9 days after tumor inoculation. This inhibition approached statistical significance when compared with growth of saline controls. Histologic responses consisted primarily of plasma cell and eosinophil infiltration. The intensity of the inflammatory response did not correlate with interleukin-2 dose. A trend toward enhanced tumor growth was seen with lower doses of interleukin-2 and when interleukin-2 therapy was initiated simultaneously with tumor inoculation. These findings suggest that high-dose recombinant interleukin-2 can prevent tumor growth if initiated after tumor inoculation. Whether this effect was caused by direct tumor cytotoxicity or mediated by the immune system is unclear. These preliminary results underscore the importance of understanding the effects of dose and schedule in the design of immunotherapy models before clinical use. (OTOLARYNGOL HEAD NECK SURG 1995;112:430-6.)

Intravenous manganese-mesoporphyrin as a magnetic resonance imaging contrast agent: An experimental model using VX-2 carcinoma in rabbits

We investigated the potential of manganese (III) mesoporphyrin (Mn-mesoporphyrin) as a hepatobiliary contrast agent for magnetic resonance (MR) imaging in rabbits given VX-2 carcinoma liver implants. Rabbits given VX-2 carcinoma liver implants (n = 8) were imaged before and after the intravenous (i.v.) administration of 0.04 mmol/kg Mn-mesoporphyrin. MR images were correlated with gross-specimen cross-sections. The distribution of Mn in various tissues following i.v. administration of 0.04 mmol/kg Mn-mesoporphyrin was determined using atomic absorption analysis. A standard panel of serum chemistries was followed over 7 days in six rabbits following this same dose of Mn-mesoporphyrin and compared with chemistries from two control rabbits. I.v. administration of 0.04 mmol/kg (25 mg/kg) Mn-mesoporphyrin resulted in improvement of tumor-to-liver contrast, with enhancement of normal liver (99.7 +/- 14.7%) and the gallbladder (442 +/- 116%), but not VX-2 tumor tissue (14.8 +/- 13.9%), (n = 8, p = .05). Analysis of tissue Mn levels 100 min after i.v. Mn-mesoporphyrin injection demonstrated preferential distribution of Mn to normal liver tissue (57.8 +/- 15.3 micrograms Mn/g) compared with VX-2 tumor (4.28 +/- 1.48 micrograms Mn/g). No significant change was found in the serum chemistries of six normal rabbits over a 7-day period after the i.v. administration of 0.04 mmol/kg Mn-mesoporphyrin. I.v. Mn-mesoporphyrin improved lesion-to-liver contrast because of preferential distribution of Mn-mesoporphyrin to normal liver parenchyma and bile.

Study on intracellular calcium localization by potassium antimonate technique in rabbit VX2 carcinoma

It is well known that a rabbit having VX2 carcinoma, which derived from virus-induced papillomas, shows hypercalcemia from the early stage of its growth. Ultrathin sections of the VX2 carcinoma were examined for the evaluation of calcium localization using a potassium antimonate technique and X-ray microanalysis. The calcium antimonate complex was shown to be most prevalent in the euchromatin and mitochondria.

3 家兎VX2癌の微細血管系に及ぼすトラネキサム酸の影響に関する研究 (第432回 大阪歯科学会例会)

3 家兎VX2癌の微細血管系に及ぼすトラネキサム酸の影響に関する研究 (第432回 大阪歯科学会例会)

Drug delivery using biodegradable microspheres

Rational delivery systems for leuprorelin acetate, a potent LHRH agonist, have been achieved by developing a microsphere system using biodegradable polymers, poly(lactic/glycolic acid) (PLGA) and polylactic acid, which sustainedly release the drug depending on the biodegradation of polymer used and persistently suppress steroidogenesis for over one and 3 months, respectively, following a single injection. To produce these systems we established a novel microencapsulation technique, the in-water drying method, and microspheres with a high trap ratio and small initial burst were obtained. A microsphere system of TRH prepared using PLGA could also continuously release the drug for 2 or 4 weeks. Using these systems effectively reduced the required dose compared with that needed with daily injection due to more continuous receptor hits on the target organs and could improve patient compliance. Chemoembolization using PLGA microspheres containing an angiogenesis inhibitor, TNP-470, resulted in dramatic regression of VX-2 carcinoma in rabbits. The microsphere system using biod-egradable polymers is very useful in designing controlled release delivery and targeted delivery to attain potent and rational therapy.

PP (ポリプロピレン) 系チューブを用いた組織内光照射法による光化学療法の基礎的研究

The purpose of this study is to evaluate the photodynamic therapy (PDT) by the intertumor movement type laser irradiation methods using the Polipuropiren type tube for the advanced cancer.Materials and Methods: The rabbit VX2carcinoma transplanted into the rabbit dorsal side of the foot. When the developing cancer reached up to the size of 32×20×20mm. A dose of 5mg/kg of the photosensitizer, a Hematoporphyrin derivative made by QUENTRON OPTICS company was administered intravenously. Immediately 24hours after administration, the polypropylene type tube was inserted into the tumor with the fiber inside which rotates with an irradiation condition of 18mm/min,12R. P. M.. A pulse repetition frequency of 80Hz and energy per pulse of 5mJ was applied consequently, along a tube with the tumor was 15J/mm.Results: The tumor around the tube was destroyed up to the extent of 28mm in diameter. We suggest that the PDT using the intertumor movement type laser irradiation methods is applicable for the treatment of advanced cancer.

MR staging of malignant musculoskeletal tumors: An experimental study on MR and pathologic correlation of rabbit VX-2 carcinoma

MR staging of malignant musculoskeletal tumors: An experimental study on MR and pathologic correlation of rabbit VX-2 carcinoma

In vitro measurement and screening of monoclonal antibody affinity using fluoroscence photobleaching

Antibody screening is a routine in vitro assay in monoclonal antibody development and production. We have recently adapted the fluorescence photobleaching method to quantify antibody mass transport and binding parameters in bulk solution (Kaufman and Jain, 1990, 1991). The present study uses this in vitro method to screen a series of monoclonal antibodies (IgG) developed against the rabbit VX2 carcinoma tumor line. These experiments indicate that the three antibodies recognize distinct epitopes on the tumor, with equilibrium binding constantsof 1.3 ± 0.5, 5.1 ± 3.6 and 2.0 ± 1.1 × 10 7 M −1 for the antibodies RVC-184, RVC-626 and RVC-779, respectively. The antibody diffusion coefficient revealed no dependence upon protein concentration or antigen bead volume fraction within the ranges investigated. It was demonstrated experimentally that the interactions conformed to a reaction limited binding model of fluorescence recovery, that the system was at equilibrium, and that non-specific binding due to the fluorescein probe was not significant. Once the non-reactive fraction of antibody is determined, this photobleaching technique does not require perturbation or physical separation of the unbound species. As such, it has many potential applications including in vivo investigation of binding parameters.

Tumor portions and necrotic portions of VX-2 carcinoma in rabbits: correlation with MRI and pathology

Tumor portions and necrotic portions of VX-2 carcinoma in rabbits: correlation with MRI and pathology

家兎ＶＸ２癌に及ぼす抗癌剤の影響に関する電子顕微鏡学的研究 腫よう血管の変化を中心として

家兎ＶＸ２癌に及ぼす抗癌剤の影響に関する電子顕微鏡学的研究 腫よう血管の変化を中心として

家兎ＶＸ２癌に対する加温処置の抗腫よう効果ならびに病理組織学的変化に関する研究

The present study was designed to examine the antitumor effect of hyperthermia alone in relation to the histopathological changes. Rabbit VX2 carcinoma was used in this study. Microwave hyperthermia (2, 450 MHz) was carried out at 41°C, 43°Cand 45°Cfor a 30-minute period. Measurement of temperature was obtained by thermister at the tumor center. The antitumor effect was determined by comparing the growth curve of VX2 carcinoma which was obtained by tumor volume calculated from tumor width after heating. Tumor angiography was performed immediately and 3, 24 and 72 hours after heating and the same specimens were observed histopathologically using Hematoxilin-Eosin stained sections.Consequently the antitumor effect was observed in the groups heated at 43°C and 45°C. In particular, the 45°C heated group showed a predominant antitumor effect. In the 41°C heated group, no antitumor effect was observed. With regard to tumor growth rate, it was relatively delayed in the 45°C heated group as compared to the 43°C heated group. In the 43°C and 45°C heated groups, tumor mitosis increased 72 hours after heating. Therefore, it was considered that recovery from damage tended to be later at higher temperatures. The histopathological changes of tumor cells after heating included pycnosis, karyorrhexis, karyolysis and eosinophilic degeneration and these changes tended to be remarkable in the tumor center rather than periphery. Tumor vessel damages showed thrombosis and dilatation of the vascular wall due to fibrin deposit. In the 45°C heated group, irreversible fibrinoid degeneration was additionaly observed. Though tumor vessel damage tended to continue as the temperature ascended, these changes were considered reversible because the contrast medium started flowing into these injured vessels with the passage of time. In the 45°C treated group, damage was observed in parts of normal vessels, therefore, the hyperthermic approach as considered to affect normal tissues at higher temperatures.

Multiple short-echo (2.5-ms) quantitation of in vivo sodium T2 relaxation.

The MR behavior of the sodium-23 nucleus in vivo is a complex problem which has generated considerable interest over the last 20 years. Early studies on excised tissue samples revealed that the sodium nucleus exhibited a two-component T2 relaxation. This biexponential T2 relaxation was characterized by a short component with a T2 = 0.7-4.8 ms, and a long component with a T2 = 7.0-26.0 ms. We have developed a 3D pulse sequence capable of performing multiple Hahn echo in vivo sodium-23 imaging at echo times as short as 2.5 ms. This sequence obtains the shorter spin echo times by presaturating the spins outside of the desired imaging region, allowing the use of nonselective rf pulses. Using this sequence we have been able to quantify the long and short T2 components of normal brain tissue, vitreous humor of the eye, and a rabbit VX-2 carcinoma. We found that gray matter and white matter of normal brain have a monoexponential T2 relaxation with T2 = 17.6 +/- 2.4 ms. The vitreous humor T2 relaxation is also monoexponential with T2 = 56.8 +/- 2.1 ms. However, we find that some of the rabbit VX2 carcinomas exhibit a biexponential T2 decay with a short component of 3.3 +/- 4.6 ms and a long component of 22.0 +/- 9.0 ms.

Selective effect of doxorubicin suspended in lipiodol on VX2 carcinoma in rabbits.

When Lipiodol Ultra-Fluid (Lipiodol) was given through arteries feeding the tumor, this material was retained in the tumor. After mixing Lipiodol and doxorubicin (adriamycin; ADR), the effect of this antitumor agent on VX2 carcinoma inoculated into the hindlimb in 57 rabbits was investigated. Size of the tumor remarkably decreased in the rabbits treated with ADR 2 mg/kg suspended in Lipiodol and given through the femoral artery. Intraarterial injection of ADR 2 mg/kg alone led to a transient decrease in size of the tumor, but there was a regrowth. The result was comparable to a finding in a group in which half the dose of ADR (1 mg/kg) suspended in Lipiodol was given intraarterially. When ADR 2 mg/kg mixed with Lipiodol was injected directly into the tumor, growth of the tumor was not completely inhibited. Lipiodolized ADR has a prominent antitumor effect, and Lipiodol has the potential to be applied as a carrier of anticancer drugs.

In vivo and in vitro 31P-NMR preliminary studies of the VX-2 carcinoma in rabbits.

In vivo and in vitro 31P-NMR spectroscopy was used to study the high energy phosphate metabolism of VX-2 tumors implanted into rabbit liver, kidney, and hind-limb muscle. Tumors, at various stages of growth, were first examined by in vivo 31P-NMR spectroscopy, then they were excised and underwent histologic examination and biochemical analysis; both in vitro 31P-NMR and standard enzymatic techniques were used. There was good correlation among the in vivo NMR spectra, the in vitro NMR data, and the biochemical analyses. Although the tumor spectra showed characteristics similar to those reported in the other tumor models, there was a striking variability in the spectra obtained from tumors implanted in the same site and from different sites. There was poor correlation between the degree of necrosis in the tumor and the tumor pH and between the Pi:ATP ratio and necrosis. This variability has important implications for the potential value of using 31P-NMR spectroscopy to monitor tumor growth and therapy in vivo.

Visualization of tumor vascularity in a rabbit VX2 carcinoma by Doppler flow mapping.

Using an ultrasonic dynamic flow imager that displays both soft tissues and color-coded flow in the same two-dimensional slice, we were able to display neovascularity in a rabbit VX2 carcinoma. Intravenous infusion of epinephrine altered the flow dynamics in two arteries, one within the tumor and one at the periphery. Further, we were also able to visualize areas of multidirectional flow presumably due to complex arterial patterns and arteriovenous shunts. It is concluded that the color-coded Doppler instrument may overcome some of the methodological problems associated with tumor diagnosis via flow characteristics in the human breast. The literature indicates that the vascular response to the vasoactive drugs or thermal stress may increase differentiation of malignant breast lesions. This experiment suggests that Doppler images and measurements may be made efficiently with color-coded Doppler images, particularly with the addition of more quantitative features to the imager.

Pharmacokinetic studies on 1-(2-chloroethyl)-3-isobutyl-3-(beta-maltosyl)-1-nitrosourea (TA-077). II. Hydrolysis by tissue homogenates and drug uptake by tumor cells in vitro.

1-(2-Chloroethyl)-3-isobutyl-3-(beta-maltosyl)-1-nitrosourea (TA-077) was hydrolyzed to its glucosyl metabolite TA-G by homogenates of guinea pig organs, rabbit VX-2 carcinoma and rat Yoshida sarcoma. The rate of TA-G formation by the kidney was the highest among the tissues examined and that by the diluted blood was undetectably low, reflecting their maltase activities. TA-077 was also hydrolyzed by suspensions of Yoshida sarcoma, AH130 hepatoma, L1210 leukemia, P388 leukemia and DBLA-10/C leukemia cells. The rate of TA-G formation was increased 10 fold by homogenizing the tumor cells. TA-G was taken up by the tumor cells much more efficiently than TA-077, explaining the higher sensitivities of the cultured tumor cells to TA-G than to TA-077. However, neither the maltase activity nor the membrane permeability to the drugs was a factor influential enough to explain the differences in drug sensitivity among the tumor cell lines.

The rabbit as an experimental model for regional chemotherapy. 2. Isolated perfusion of hindlimbs.

Regional chemotherapy to a tumour is most commonly delivered by intra-arterial infusion. An alternative method of regional drug delivery, isolated perfusion, may be used where anatomical considerations permit. The technique of isolated perfusion in the rabbit hindlimb is described. The use of this model with the implantable rabbit VX2 carcinoma allows estimation of drug uptake by normal tissues, primary tumour and popliteal lymph node metastases. Correlation of such data with blood flow measurements enables targeting of new cytotoxic agents to be evaluated. The effect of perfusate composition on tissue uptake of such an agent, the plant toxin ricin, has been determined.

Electrolyte and glucose metabolism in VX-2 carcinoma of the rabbit

Biochemical and other parameters in VX-2 carcinoma in rabbits were evaluated. VX-2 carcinoma not only produced hypercalcemia but also hypophosphatemia and 25- OH-vitamin D deficiency. An increased turnover of 25- OH-vitamin D seems likely. Serum parathyroid hormone and urinary cyclic AMP did not increase. Hypokalemia occurred in association with hypophosphatemia and lowered blood glucose within 1 week after tumor transplantation. At the end of the experiment glucose and insulin were both below the control range. It is concluded that VX-2 carcinoma in rabbits yields much more complex biochemical alterations than reported before on calcium metabolism.

Collagenase activity in rabbit carcinoma: cell source and cell interactions.

Fibroblast-like cells (F-cells) and epithelial-like (E-cells) derived from cultures of rabbit VX-2 carcinoma released collagenase in both active and latent forms in serum-free medium at a level higher than that of normal rabbit fibroblast cultures. The enhanced capacity of the F-cells to release the enzyme, however, continued only for a few passages and then decreased significantly to a low level similar to that of the normal fibroblasts. The enzyme-release by the E-cells continued for a few more passages at a relatively moderate level, higher than that of normal fibroblasts. The release of collagenase in cultures of F-cells was enhanced by the presence of E-cells in mixed cultures as well as by medium conditioned by the E-cells type. Addition of cytochalasin B at 2 micrograms/ml did not significantly effect the enzyme activity released in the cultures. Serum from tumor-bearing rabbits appeared to stimulate the release of enzyme activity in cultures of either cell type.