Immunohistochemical expression of p63 protein and calponin in canine mammary tumours.

The aim of this study was to compare the expression of p63 protein and calponin in terms of their affinity and specificity for myoepithelial cells in canine mammary tumours. The studied material included 10 benign and 32 malignant mammary tumours from female dogs treated with mastectomy. Primary mouse monoclonal antibodies directed against p63 protein clone 4A4 and calponin clone CALP were used in single- and doublestain system of immunohistochemical reaction.

Expression of the Short Form of RON/STK in Feline Mammary Carcinoma.

RON is a tyrosine kinase receptor activated by the macrophage-stimulating protein (MSP) ligand that is overexpressed in human breast cancer. In humans, RON protein can be present in different isoforms, and the most studied isoform is represented by the short form of RON ( sf-RON), which is generated by an alternative promoter located in intron 10 of the RON complementary DNA (cDNA). It plays an important role in breast cancer progression.

PDGFR-α, PDGFR-β, VEGFR-2 and CD117 expression in canine mammary tumours and evaluation of the in vitro effects of toceranib phosphate in neoplastic mammary cell lines.

Canine mammary tumours (CMTs) are one of the most common malignancies in bitches. Platelet-derived growth factor receptor (PDGFR) α and β, vascular endothelial growth factor receptor-2 (VEGFR-2) and CD117 are tyrosine kinase receptors involved in several tumours and represent suitable targets for specific therapy with toceranib phosphate. The purpose of this study was to evaluate the expression of these receptors in the pathogenesis and progression of CMTs.

Demethylating and anti-hepatocarcinogenic potential of hesperidin, a natural polyphenol of Citrus juices.

Hepatocellular carcinoma (HCC) is a neoplasia representing the fifth most common malignancy worldwide and the third cause of death from cancer. Diets with high content in fruits and vegetables are widely recommended for their health-promoting properties, among them, the protection against diabetes, cancer, and cardiovascular diseases. Hesperidin is the most important phenol in the orange fruit with well-known health benefits.

Myoepithelial cells in canine mammary tumours.

Mammary tumours are the most common neoplasms of female dogs. Compared to mammary tumours of humans and cats, myoepithelial (ME) cell involvement is common in canine mammary tumours (CMT) of any subtype. Since ME cell involvement in CMT influences both histogenetic tumour classification and prognosis, correct identification of ME cells is important.

Progesterone receptor isoform A may regulate the effects of neoadjuvant aglepristone in canine mammary carcinoma.

Background: Progesterone receptors play a key role in the development of canine mammary tumours, and recent research has focussed on their possible value as therapeutic targets using antiprogestins. Cloning and sequencing of the progesterone receptor gene has shown that the receptor has two isoforms, A and B, transcribed from a single gene. Experimental studies in human breast cancer suggest that the differential expression of progesterone receptor isoforms has implications for hormone therapy responsiveness.

Uncommon acute neurologic presentation of canine distemper in 4 adult dogs.

Four uncommon cases of canine distemper (CD) were diagnosed in vaccinated adult dogs. All dogs had acute onset of neurologic signs, including seizures, abnormal mentation, ataxia, and proprioceptive deficits. Polymerase chain reaction for CD virus was positive on cerebrospinal fluid in 2 cases.

The antiprogestins mifepristone and onapristone reduce cell proliferation in the canine mammary carcinoma cell line CMT-U27.

Canine mammary tumours (CMTs) represent nearly half of all tumours in female dogs and some 50% have malignant behaviour. Simple epithelial carcinomas have shorter disease free periods after surgery and a higher reduction of the proliferation index reduction after antiprogestin aglepristone treatment in vivo related to the expression of progesterone receptors (PR). These findings make simple carcinomas good candidates for endocrine therapy.

Primary central nervous system T-cell lymphoma mimicking meningoencephalomyelitis in a cat.

A cat was presented with right head tilt and circling. The lack of expression of virus antigens did not support the postmortem diagnosis of encephalomyelitis pointing to a diffuse primary central nervous system T-cell lymphoma on the basis of CD3 and CD45R co-expression with absence of CD79α staining.

Activation of mammalian target of rapamycin (mTOR) in triple negative feline mammary carcinomas.

Background: Triple negative breast cancer (TNBC) in humans is defined by the absence of oestrogen receptor (ER), progesterone receptor (PR) and HER2 overexpression. Mammalian target of rapamycin (mTOR) is overexpressed in TNBC and it represents a potential target for the treatment of this aggressive tumour. Feline mammary carcinoma (FMC) is considered to be a model for hormone-independent human breast cancer.

Estrogen receptor (ESR) 2 partially offsets the absence of ESR1 in gonadotropes of pituitary-specific Esr1 knockout female mice.

Estrogen receptor 1 and 2 (ESR1 and 2) mediate estrogen (E) action on gonadotrope function. While much is known about the effects of ESR1 on the gonadotrope, there is still some controversy regarding the effects of ESR2. To investigate the role of ESR2 in the gonadotrope, 45-day-old female mice of two different genotypes were used: wild type (WT) and pituitary (gonadotropes and thyrotropes)-specific Esr1 knockout (KO).

Expression of 14-3-3 σ protein in normal and neoplastic canine mammary gland.

14-3-3 σ protein is a negative cell cycle regulator, with both reduced and elevated levels associated with cancer in humans. This study assessed the expression of this protein in canine mammary tissues using immunohistochemistry and Western blotting. 14-3-3 σ was detected in 97% of the mammary tissue samples examined and was found in both myoepithelial (MECs) and epithelial (ECs) cells.

Immunoneutralization of inhibin in cycling rats increases follicle-stimulating hormone secretion, stimulates the ovary and attenuates progesterone receptor-dependent preovulatory luteinizing hormone secretion.

Passive immunization against inhibin with an anti-inhibin serum (AIS) during the diestrous phase in cycling rats increased follicle-stimulating hormone secretion, stimulated the ovaries and reduced the magnitude of the luteinizing hormone (LH) surge in the afternoon of proestrus. The involvement of gonadotrope progesterone receptor (PR) expression/action in the inhibitory effects of the follicle-stimulating hormone-dependent putative ovarian factor gonadotropin surge-attenuating factor on preovulatory LH secretion was studied in the absence of circulating free inhibin. Proestrous pituitaries from rats injected with AIS or a non-immune serum (NIS) were studied for determination of PR-AB and PR-B mRNAs by RT-PCR and PR-B and PR-A isoform proteins by Western blot.

Expression of oestrogen and progesterone receptors in canine sebaceous gland tumours.

Sebaceous gland oestrogen alpha (ERalpha) and progesterone (PR) receptor expression was examined immunohistochemically in 26 and 32 dogs respectively with sebaceous gland hyperplasia/adenomas, epitheliomas and carcinomas, and in the glands of 10 healthy controls. The mean percentage of ERalpha positive nuclei in control sebaceous glands was 21.31% compared with 11.

Activation of estrogen receptor-alpha induces gonadotroph progesterone receptor expression and action differently in young and middle-aged ovariectomized rats.

Background: We attempted to define the effect of estrogen receptor (ER)alpha activation on gonadotroph progesterone receptor (PR) expression (mRNA and protein) and action (GnRH-stimulated and GnRH self-priming) in short- and long-term ovariectomized (OVX) rats.

Methods: Two weeks or 1 year after OVX, rats were injected over 3 days with 125 microg/kg of estradiol benzoate (EB), 7.5 mg/kg of the selective ERalpha agonist propylpyrazole triol (PPT), or 15 mg/kg of the selective ER modulator tamoxifen (TX).

Immunohistochemical localisation of 14-3-3 sigma protein in normal canine tissues.

The 14-3-3 sigma protein, also called stratifin, belongs to the highly conserved family of 14-3-3 acid proteins, which are involved in the modulation of diverse signal transduction pathways. Loss of 14-3-3 sigma expression has been observed in several types of human cancers, suggesting that it may have a role as a tumour suppressor gene. The 14-3-3 sigma protein has been localised in normal human tissues exclusively in various epithelial cell types.

Ovarian stimulation with FSH reduces phosphorylation of gonadotrope progesterone receptor and LH secretion in the rat.

Administration of human FSH (hFSH) to cyclic rats during the dioestrous phase attenuates progesterone receptor (PR)-dependent events of the preovulatory LH surge in pro-oestrus. The increased bioactivity of the putative ovarian gonadotropin surge inhibiting/attenuating factor induced by hFSH treatment is not associated with a decrease in PR protein expression, and the possibility of its association at a PR posttranslational effect has been raised. The present experiments aimed to analyse PR phosphorylation status in the gonadotrope of rats with impaired LH secretion induced by in vivo hFSH injection.

Morphological effects of oestradiol-17beta, and selective oestrogen receptor alpha and beta agonists on luteinising hormone-secreting cells in tamoxifen-treated ovariectomised rats.

To investigate the role played by the different rat gonadotroph oestrogen receptor (ER) pools in the effects of oestradiol-17beta (E2) on gonadectomy cells, two-week ovariectomised (OVX) rats were used. The basic experimental group of rats was injected with 3 mg of the selective ER modulator tamoxifen (TX) on days 15-20 after OVX. Groups of TX-treated OVX rats were additionally injected on days 18-20 after OVX with 10 microg oestradiol benzoate (EB), 1 mg of the selective ERalpha agonist propylpyrazole triol (PPT), or 1 mg of the selective ERbeta diarylpropionitrile (DPN).

The ovary-mediated FSH attenuation of the LH surge in the rat involves a decreased gonadotroph progesterone receptor (PR) action but not PR expression.

Hyperstimulation of ovarian function with human FSH (hFSH) attenuates the preovulatory surge of LH. These experiments aimed at investigating the mechanism of ovarian-mediated FSH suppression of the progesterone (P(4)) receptor (PR)-dependent LH surge in the rat. Four-day cycling rats were injected with hFSH, oestradiol benzoate (EB) or vehicle during the dioestrous phase.

Molecular characterization and expression analysis of the gene coding for the porcine beta(3) integrin subunit (CD61).

Integrins are heterodimeric cell adhesion molecules with major roles in a variety of biological processes ranging from cell migration to tissue organization, immune and non-immune defense mechanisms and oncogenic transformation. Members of the beta(3) integrin subfamily are composed of a beta(3) subunit (CD61) non-covalently associated with two alpha subunits, alpha(IIb) (CD41) and alpha(v) (CD51), to constitute a group of transmembrane glycoproteins that participate in many physiologically important events. This investigation has focused on the molecular characterization of the cDNA encoding the porcine beta(3) integrin subunit.

Proto-oncogene HER-2 in normal, dysplastic and tumorous feline mammary glands: an immunohistochemical and chromogenic in situ hybridization study.

Background: Feline mammary carcinoma has been proposed as a natural model of highly aggressive, hormone-independent human breast cancer. To further explore the utility of the model by adding new similarities between the two diseases, we have analyzed the oncogene HER-2 status at both the protein and the gene levels.

Methods: Formalin-fixed, paraffin-embedded tissue samples from 30 invasive carcinomas, 7 benign lesions and two normal mammary glands were analyzed.

The integrated action of oestrogen receptor isoforms and sites with progesterone receptor in the gonadotrope modulates LH secretion: evidence from tamoxifen-treated ovariectomized rats.

The specific role of each oestrogen receptor (ER) isoform (alpha and beta ) and site (nucleus and plasma membrane) in LH release was determined in ovariectomized (OVX) rats injected over 6 days (days 15-20 after OVX) with a saturating dose (3 mg/day) of tamoxifen (TX), a selective ER modulator with nuclear ERalpha agonist actions in the absence of oestrogen. This pharmacological effect of TX was demonstrated by the fact that it was blocked by the selective ERalpha antagonist methyl-piperidinopyrazole. Over the past 3 days of the 6-day TX treatment, rats received either 25 microg/day oestradiol benzoate (EB), 1.

Oestradiol-17beta inhibits tamoxifen-induced LHRH self-priming blocking hormone-dependent and ligand-independent activation of the gonadotrope progesterone receptor in the rat.

In the rat, administration of tamoxifen (TX) in the absence of oestrogen (E) induces LHRH self-priming, the progesterone receptor (PR)-dependent property of LHRH that increases gonadotrope responsiveness to itself. The oestrogen-dependent PR can be phosphorylated/activated by progesterone (P4) and, in the absence of the cognate ligand, by intracellular LHRH signals, particularly cAMP/protein kinase A. We have recently found that oestradiol-17beta (E2), acting on a putative membrane estrogen receptor-alpha in the gonadotrope, inhibits this agonist action of TX.