Ana I. Faustino-Rocha

Estimation of rat mammary tumor volume using caliper and ultrasonography measurements

Mammary tumors similar to those observed in women can be induced in rats by intraperitoneal administration of N-methyl-N-nitrosourea. Determining tumor volume is a useful and quantitative way to monitor tumor progression. In this study, the authors measured dimensions of rat mammary tumors using a caliper and using real-time compound B-mode ultrasonography. They then used different formulas to calculate tumor volume from these tumor measurements and compared the calculated tumor volumes with the real tumor volume to identify the formulas that gave the most accurate volume calculations. They found that caliper and ultrasonography measurements were significantly correlated but that tumor volumes calculated using different formulas varied substantially. Mammary tumors seemed to take on an oblate spheroid geometry. The most accurate volume calculations were obtained using the formula V = (W2 × L)/2 for caliper measurements and the formula V = (4/3) × π × (L/2) × (L/2) × (D/2) for ultrasonography measurements, where V is tumor volume, W is tumor width, L is tumor length and D is tumor depth.

The effects of repeated oral gavage on the health of male CD-1 mice

Oral gavage is a widely used method for administering substances to animals in pharmacological and toxicological studies. The authors evaluated whether oral gavage causes behavioral indicators of stress, increased mortality rate, alterations in food and water consumption and body weight or histological lesions in CD-1 mice. Gavage was carried out once per d for 5 d per week over 6 consecutive weeks. The mortality rate of mice in this study was 15%. Mice subjected to gavage did not undergo changes in food or water consumption during the study, and their mean body weights and relative organ weights were similar to those of mice in the control group. Serum cortisol levels at the time of euthanasia in mice in both groups were within the normal range. Histopathology showed acute esophagitis and pleurisy, indicative of perforation of the esophagus, in the two mice that died but no abnormalities in the other mice. The results suggest that animal stress and mortality related to oral gavage can be minimized when the procedure is carried out by an experienced technician.

Ultrasonographic, thermographic and histologic evaluation of MNU-induced mammary tumors in female Sprague-Dawley rats

BACKGROUND As the worldwide breast cancer burden increases, non-invasive tools, such as ultrasonography and thermography are being increasingly sought after. N-methyl-N-nitrosourea-induced rat mammary tumors are important tools to investigate the usefulness of such imaging techniques. OBJECTIVE This study aimed to integrate both ultrasonographic and thermographic approaches to the vascularization and the superficial temperature of chemically-induced rat mammary tumors. MATERIALS AND METHODS Twenty-five female Sprague-Dawley rats were divided into two groups: group I (intraperitoneally administered with N-methyl-N-nitrosourea) and group II (control group). Thirty-five weeks after the administration of the carcinogen, mammary tumors were evaluated using Power Doppler, B Flow and Contrast-enhanced ultrasound, thermography and histology analyses. RESULTS Group I animals showed an average of 2.5 mammary tumors per animal, mostly papillary and cribriform non-invasive carcinomas. B Flow detected higher counts of colour pixels than Power Doppler. Contrast-enhanced ultrasound analysis showed a centripetal enhancement order of contrast agent and clear margins. Maximum tumor temperature and thermal amplitude determined by thermography were significantly correlated with tumor volume and with color pixel density, determined by Power Doppler. CONCLUSION B Flow was more sensitive than Power Doppler in detecting tumor vessels, but Power Doppler correlates with thermographic data concerning superficial temperature and may reflect tumor angiogenesis.

Long-term exercise training as a modulator of mammary cancer vascularization

BACKGROUND Breast cancer remains a leading cause of death by cancer worldwide. It is commonly accepted that angiogenesis and the expression of angiogenic factors such as vascular endothelial growth factor-A (VEGF-A) is associated with the increased risk of metastasis and poor patient outcome. OBJECTIVE This work aimed to evaluate the effects of long-term exercise training on the growth and vascularization of mammary tumors in a rat model. MATERIALS AND METHODS Fifty female Sprague-Dawley rats were divided into four groups: two N-methyl-N-nitrosourea (MNU)-exposed groups (exercised and sedentary) and two control groups (exercised and sedentary). MNU was administered once, intraperitoneally at 7 weeks-old. Animals were then exercised on a treadmill for 35 weeks. Mammary tumors were evaluated using thermography, ultrasonography [Power Doppler (PDI), B Flow and contrast-enhanced ultrasound (CEUS)], and immunohistochemistry (VEGF-A). RESULTS Both, MNU sedentary and exercised groups showed 100% of tumor incidence, but exercised animals showed less tumors with an increased latency period. Exercise training also enhanced VEGF-A immunoexpression and vascularization (microvessel density, MVD) (p<0.05), and reduced histological aggressiveness. Ultrasound and thermal imaging analysis confirmed the enhanced vascularization of tumors on exercised animals. CONCLUSION Long-term exercise training increased VEGF-A expression, leading to enhanced tumor vascularization and reduced tumor burden, multiplicity and histological aggressiveness.

Cytokeratin 7/19 expression in N-diethylnitrosamine-induced mouse hepatocellular lesions: implications for histogenesis

Hepatocellular carcinoma (HCC) is a common malignancy with poor clinical outcome, whose histogenesis is the subject of intense debate. Specifically, expression of cytokeratins (CKs) 7 and 19, associated with aggressive biological behaviour, is proposed to reflect a possible progenitor cell origin or tumour dedifferentiation towards a primitive phenotype. This work addresses that problem by studying CKs 7 and 19 expression in N‐diethylnitrosamine (DEN)‐induced mouse HCCs. ICR mice were divided into six DEN‐exposed and six matched control groups. Samples were taken from each group at consecutive time points. Hyperplastic foci (13 lesions) occurred at 29–40 weeks (groups 8, 10 and 12) with diffuse dysplastic areas (19 lesions) and with one hepatocellular adenoma (HCA) (at 29 weeks). HCCs (4 lesions) were observed 40 weeks after the first DEN administration (group 12). CKs 7 and 19 showed identical expression patterns and located to large, mature hepatocytes, isolated or in small clusters. Hyperplastic foci and the single HCA were consistently negative for both markers, while dysplastic areas and HCCs were positive. These results support the hypothesis that CKs 7 and 19 expression in hepatocellular malignancies results from a dedifferentiation process rather than from a possible progenitor cell origin.

Celecoxib promotes degranulation of CD8(+) T cells in HPV-induced lesions of K14-HPV16 transgenic mice.

AIMS Human papillomavirus (HPV) is a known biologic carcinogen which is commonly transmitted through sexual intercourse. CD8(+) T cells are known effectors against tumour cells and an important prognostic marker in HPV-induced cancers. COX-2 inhibitors enhance CD8(+) T cell activity against some cancers. In this work, we sought to study the presence and activation of CD8(+) T lymphocytes in lesions from K14-HPV16 transgenic mice and the immunomodulatory effect of celecoxib (CXB) over these cells. MAIN METHODS Skin samples of CXB-treated and untreated HPV16(-/-) and HPV16(+/-) mice were enzymatically digested and analysed by flow cytometry to assess CD8(+) and CD8(+)CD107a(+) T cell infiltrates. Matched skin samples were classified histologically. KEY FINDINGS HPV16(+/-) mice presented higher CD8(+) T cell infiltration than HPV16(-/-) animals (P<0.001). Older HPV16(+/-) animals showed epidermal dysplasia and increased percentages of CD8(+)CD107a(+) T cells compared with younger animals with hyperplasia (P<0.001), validating this model for testing the effects of celecoxib on CD8(+) T cells. CXB-treated HPV16(+/-) mice showed higher percentages of CD8(+)CD107a(+) T cells compared with untreated HPV16(+/-) animals (P<0.01), but no differences were observed concerning the progression of epidermal lesions. SIGNIFICANCE These findings indicate that celecoxib enhances the degranulation of CD8(+) T cells on HPV16-induced lesions, suggesting the potential clinical use of COX-2 inhibitors. Additionally, this study demonstrates the usefulness of the K14-HPV16 mouse model for testing therapeutic immunomodulatory approaches.

Long-term exercise training prevents mammary tumorigenesis-induced muscle wasting in rats through the regulation of TWEAK signalling.

Exercise training has been suggested as a non‐pharmacological approach to prevent skeletal muscle wasting and improve muscle function in cancer cachexia. However, little is known about the molecular mechanisms underlying such beneficial effect. In this study, we aimed to, firstly, examine the contribution of TWEAK signalling to cancer‐induced skeletal muscle wasting and, secondly, evaluate whether long‐term exercise alters TWEAK signalling and prevents muscle wasting.

Antihistamines as promising drugs in cancer therapy

&NA; Histamine is a biogenic amine, synthetized and released by mast cells, which acts as a vasodilator in several pathologic processes, namely in allergies and conjunctivitis. Its role on cancer is not fully understood. High levels of histamine have been associated with a bivalent behavior in regulation of several tumors (i.e. cervical, ovarian, vaginal, uterine, vulvar, colorectal cancer, and melanoma), promoting or inhibiting their growth. Histamine receptors (H1, H2, H3 and H4) are present in a vast group of cells, including tumor cells, making them sensitive to histamine variations. In this work, we review the role of mast cells and histamine on cancer development and the possibility of use antihistamines in the clinical management of this disease. Graphical abstract Figure. No caption available.

Experimental mammary carcinogenesis - Rat models

&NA; Mammary cancer is one of the most common cancers, victimizing more than half a million of women worldwide every year. Despite all the studies in this field, the current therapeutic approaches are not effective and have several devastating effects for patients. In this way, the need to better understand the mammary cancer biopathology and find effective therapies led to the development of several rodent models over years. With this review, the authors intended to provide the readers with an overview of the rat models used to study mammary carcinogenesis, with a special emphasis on chemically‐induced models. Graphical abstract Figure. No caption available.

Trihalomethanes in Liver Pathology: Mitochondrial Dysfunction and Oxidative Stress in the Mouse

Trihalomethanes (THMs) are disinfection byproducts found in chlorinated water, and are associated with several different kinds of cancer in human populations and experimental animal models. Metabolism of THMs proceeds through enzymes such as GSTT1 and CYP2E1 and gives rise to reactive intermediates, which form the basis for their toxic activities. The aim of this study was to assess the mitochondrial dysfunction caused by THMs at low levels, and the resulting hepatic histological and biochemical changes in the mouse. Male ICR mice were administered with two THMs: dibromochloromethane (DBCM) and bromodichloromethane (BDCM); once daily, by gavage, to a total of four administrations. Animals were sacrificed four weeks after DBCM and BDCM administrations. Blood biochemistry was performed for alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (TB), albumin (Alb), total protein (TP), creatinine, and urea. Animals exposed to DBCM and BDCM showed elevated ALT and TB levels (p < 0.05) as compared with controls. Histological analysis confirmed the presence of vacuolar degenerescence and a multifocal necrotizing hepatitis in 33% of animals (n = 2). Mitochondrial analysis showed that THMs reduced mitochondrial bioenergetic activity (succinate dehydrogenase (SQR), cytochrome c oxidase (COX), and ATP synthase) and increased oxidative stress (glutathione S‐transferase (GST)) in hepatic tissues (p < 0.05). These results add detail to the current understanding of the mechanisms underlying THM‐induced toxicity, supporting the role of mitochondrial dysfunction and oxidative stress in liver toxicity caused by DBCM and BDCM.