Data for: Therapy with multi-epitope virus-like particles of B19 parvovirus reduce tumor growth and lung metastasis in an aggressive breast cancer mouse model

Published: 31-03-2020| Version 1 | DOI: 10.17632/tvxg8b24ks.1
Contributors:
Leticia Moreno-Fierros,
Angel Jimenez Chavez

Description

the results of the experiments corresponding to mice with triple negative breast cancer immunized with virus-like particles of parvovirus B19 containing multiple neoepitopes are shown. Female, BALB/c mice, 6–8 weeks of age were used for this study. The mice were kept in micro-isolators, with sterile filter covers, had ad libitum access to water and food, 4T1 mouse mammary carcinoma cells (ATCC, Manassas, Virginia, USA) were maintained for a limited time in vitro by passages in RPMI-1640 medium (Gibco®, Grand Island, New York, USA), containing penicillin (100 U/mL), streptomycin (100 μg/mL) and fungicide (0.75 μg/mL) (Sigma Aldrich, St. Luis, Misuri, USA) and supplemented with 10% FBS (Gibco®) The BALB/c mice were randomly separated into experimental groups (n = 5–8) as follows: vehicle (PBS), WT-VLPs (50μg), WT-VLPs + adjuvant (protoxin Cry1Ac 50 μg), rMe-VLPs (50 μg,) and rMe-VLPs + adjuvant (protoxin Cry1Ac 50 μg). The tumors were induced by subcutaneous injection, into the sixth breast of the mice, of 3 x 103 4T1 cells that were freshly obtained from cell culture, with a viability greater than 90% (evaluated by trypan blue exclusion). The treatments were administered intraperitoneally and peritumorally during the experiment every 7 days, from day 7 post tumor induction. Tumor growth was monitored with a digital caliper every 3 days and tumor volume was calculated according to the formula V = L x S2 / 2, where L is the longest side and S the shortest. On day 36 post-tumor induction, the animals were sacrificed using humane methods. The spleens, inguinal nodes, lungs, and the tumors were obtained for further analysis at indicated days. It is important to mention that in this work, we used a lower number of 4T1 cells (3 x 103) to induce orthotopic tumors in BALB/c mice. This cell concentration was chosen to avoid the induction of necrotic processes in the tumors. In fact, when a higher concentration of cells was used, we observed necrosis. We wanted to avoid the induction of necrosis because it provokes painful tissue lesions in the animals, making it necessary to sacrifice the mice prematurely, and thus complicating the evaluation of the antitumor treatments. Lung metastasis For the analysis of the macro-metastases in the lungs, the same scheme described above was used, resulting in an orthotopic model of metastasis. During sacrifice, the lungs were filled with 1 mL of a 10% India Ink solution (Winsor & Newton, London, UK), in PBS, through the trachea with the help of a cannula. The trachea was blocked by surgical thread and the lungs were extracted and washed 3 times with 10 mL of Fekete´s solution (85 mL 70% ethanol, 10 mL 10% paraformaldehyde, and 5 mL acetic acid) and, the lungs were fixed in the same solution overnight. The macroscopic foci were counted and photographed with a stereoscopic microscope, OLYMPUS SZ CTV (Olympus, Tokyo, Japan).

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