Extra-Virgin Olive Oil and Its Minor Compounds Influence Apoptosis in Experimental Mammary Tumors and Human Breast Cancer Cell Lines.

Breast cancer is the most common malignancy among women worldwide. Modifiable factors such as nutrition have a role in its etiology. In experimental tumors, we have observed the differential influence of high-fat diets in metabolic pathways, suggesting a different balance in proliferation/apoptosis. In this work, we analyzed the effects of a diet high in n-6 polyunsaturated fatty acids (PUFA) and a diet high in extra-virgin olive oil (EVOO) on the histopathological features and different cell death pathways in the dimethylbenz(a)anthracene-induced breast cancer model. The diet high in n-6 PUFA had a stimulating effect on the morphological aggressiveness of tumors and their proliferation, while no significant differences were found in groups fed the EVOO-enriched diet in comparison to a low-fat control group. The high-EVOO diet induced modifications in proteins involved in several cell death pathways. In vitro analysis in different human breast cancer cell lines showed an effect of EVOO minor compounds (especially hydroxytyrosol), but not of fatty acids, decreasing viability while increasing apoptosis. The results suggest an effect of dietary lipids on tumor molecular contexts that result in the modulation of different pathways, highlighting the importance of apoptosis in the interplay of survival processes and how dietary habits may have an impact on breast cancer risk.

A high extra-virgin olive oil diet induces changes in metabolic pathways of experimental mammary tumors.

Breast cancer is the most common malignancy in women worldwide, and environmental factors, especially diet, have a role in the etiology of this disease. This work aimed to investigate the influence of high fat diets (rich in corn oil or extra virgin olive oil -EVOO-) and the timing of dietary intervention (from weaning or after induction) on tumor metabolism in a seven,12-dimethylbenz[a]anthracene (DMBA)-induced breast cancer model in rat. The effects of lipids (oils and fatty acids) have also been investigated in MCF-7 cells. The results have confirmed different effects on tumor progression depending on the type of lipid. Molecular analysis at mRNA, protein and activity level of enzymes of the main metabolic pathways have also shown differences among groups. Thus, the animals fed with the EVOO-enriched diet developed tumors with less degree of clinical and morphological malignancy and showed modified glucose and mitochondrial metabolism when compared to the animals fed with the corn oil-enriched diet. Paradoxically, no clear influence on lipid metabolism by the high fat diets was observed. Considering previous studies on proliferation and apoptosis in the same samples, the results suggest that metabolic changes have a role in the molecular context that results in the modulation of different signaling pathways. Moreover, metabolic characteristics, without the context of other pathways, may not reflect tumor malignancy. The time of dietary intervention plays also a role, suggesting the importance of metabolic plasticity and the relation with mammary gland status when the tumor is induced.

One-Step Nucleic Acid Amplification (OSNA) of Sentinel Lymph Node in Early-Stage Endometrial Cancer: Spanish Multicenter Study (ENDO-OSNA).

The objective of this study was to evaluate the efficacy of one-step nucleic acid amplification (OSNA) for the detection of sentinel lymph node (SLN) metastasis compared to standard pathological ultrastaging in patients with early-stage endometrial cancer (EC). A total of 526 SLNs from 191 patients with EC were included in the study, and 379 SLNs (147 patients) were evaluated by both methods, OSNA and standard pathological ultrastaging. The central 1 mm portion of each lymph node was subjected to semi-serial sectioning at 200 µm intervals and examined by hematoxylin-eosin and immunohistochemistry with CK19; the remaining tissue was analyzed by OSNA for CK19 mRNA. The OSNA assay detected metastases in 19.7% of patients (14.9% micrometastasis and 4.8% macrometastasis), whereas pathological ultrastaging detected metastasis in 8.8% of patients (3.4% micrometastasis and 5.4% macrometastasis). Using the established cut-off value for detecting SLN metastasis by OSNA in EC (250 copies/µL), the sensitivity of the OSNA assay was 92%, specificity was 82%, diagnostic accuracy was 83%, and the negative predictive value was 99%. Discordant results between both methods were recorded in 20 patients (13.6%). OSNA resulted in an upstaging in 12 patients (8.2%). OSNA could aid in the identification of patients requiring adjuvant treatment at the time of diagnosis.

Complete Loss of EPCAM Immunoexpression Identifies EPCAM Deletion Carriers in MSH2-Negative Colorectal Neoplasia.

The use of epithelial cell adhesion molecule (EPCAM) immunohistochemistry (IHC) is not included in the colorectal cancer (CRC) screening algorithm to detect Lynch syndrome (LS) patients. The aim of the present study was to demonstrate that EPCAM IHC is a useful tool to guide the LS germ-line analysis when a loss of MSH2 expression was present. We retrospectively studied MSH2 and EPCAM IHC in a large series of 190 lesions composed of malignant neoplasms (102), precursor lesions of gastrointestinal (71) and extra-gastrointestinal origin (9), and benign neoplasms (8) from different organs of 71 patients suspicious of being LS due to MSH2 alterations. LS was confirmed in 68 patients, 53 with MSH2 mutations and 15 with EPCAM 3'-end deletions. Tissue microarrays were constructed with human normal tissues and their malignant counterparts to assist in the evaluation of EPCAM staining. Among 154 MSH2-negative lesions, 17 were EPCAM-negative, including 10 CRC and 7 colorectal polyps, and 5 of them showed only isolated negative glands. All lesions showing a lack of EPCAM expression belonged to patients with EPCAM 3'-end deletions. EPCAM IHC is a useful screening tool, with 100% specificity to identify LS patients due to EPCAM 3'-end deletions in MSH2-negative CRC and MSH2-negative colorectal polyps.

A high-corn-oil diet strongly stimulates mammary carcinogenesis, while a high-extra-virgin-olive-oil diet has a weak effect, through changes in metabolism, immune system function and proliferation/apoptosis pathways.

Breast cancer is the most common malignancy in women worldwide, and dietary lipids are important environmental factors influencing its etiology. We have investigated the effects, and the mechanisms associated, of high-fat diets on 7,12-dimethylbenz(a)anthracene-induced rat mammary tumors. Animals were fed a low-fat, a high-corn-oil (HCO) or a high-extra-virgin-olive-oil (HOO) diet from weaning or after induction. The HCO diet had a clear stimulating effect on mammary carcinogenesis, especially when dietary intervention started after induction, whereas the tumors from HOO diet groups exhibited clinical and morphological characteristics similar to those from low-fat controls. Transcriptomic and further protein and immunohistochemical analyses of tumors also indicated different modulatory effects of high-fat diets affecting relevant biological functions: metabolism, immunosurveillance and proliferation/apoptosis pathways. Thus, the results suggested different metabolic adaptations with increased glycolysis by effect of HOO diet. Moreover, leukocyte tumor infiltration and inflammation mediators showed increased cytotoxic T cells and decreased TGFß1 expression by the HOO diet, while the HCO one increased arginase expression and IL-1α plasma levels. Furthermore, the study of proteins controlling proliferation/apoptosis pathways (Sema3A, Stat5, Smad1, Casp3) suggested an increase in proliferation by the HCO diet and an increase of apoptosis by the diet rich in olive oil. In conclusion, the HCO diet clearly stimulated mammary carcinogenesis, especially in the promotion phase, and induced molecular changes suggesting increased tumor proliferation/apoptosis balance and a proinflammatory microenvironment. The HOO diet, despite being high fat, had a weaker effect on tumorigenesis probably related to metabolic adaptations, enhanced immunosurveillance and increased apoptosis.

Dietary extra-virgin olive oil and corn oil differentially modulate the mRNA expression of xenobiotic-metabolizing enzymes in the liver and in the mammary gland in a rat chemically induced breast cancer model.

High extra-virgin olive oil (EVOO) and corn oil diets differentially modulate experimental mammary carcinogenesis. We have investigated their influence on the initiation stage through the modulation of the expression of xenobiotic-metabolizing enzymes (XMEs) in the liver and the mammary gland. Female Sprague-Dawley rats were fed a low-fat (LF), high corn oil (HCO), or high EVOO (HOO) diet from weaning and gavaged with 7,12-dimethylbenz(a)anthracene (DMBA). The HCO diet increased the mRNA levels of the phase I enzymes CYP1A1, CYP1A2 and, to a lesser extent, CYP1B1, in the liver. The Aryl hydrocarbon receptor (AhR) seemed to be involved in this upregulated CYP1 expression. However, a slight trend toward an increase in the mRNA levels of the phase II enzymes GSTP1 and NQO1 was observed with the HOO diet. At least in the case of GSTP1, this effect was linked to an increased Nrf2 transactivation activity. This different regulation of the XMEs expression led, in the case of the HCO diet, to a balance between the production of active carcinogenic compounds and their inactivation tilted toward phase I, which would stimulate DMBA-induced cancer initiation, whereas the HOO diet was associated with a slower phase I metabolism accompanied by a faster phase II detoxification, thus reducing the output of the active compounds to the target tissues. In the mammary gland, the differential effects of diets may be conditioned by the state of cell differentiation, sexual maturity, and hormone metabolism.

Identification of ALK gene alterations in urothelial carcinoma.

BACKGROUND: Anaplastic lymphoma kinase (ALK) genomic alterations have emerged as a potent predictor of benefit from treatment with ALK inhibitors in several cancers. Currently, there is no information about ALK gene alterations in urothelial carcinoma (UC) and its correlation with clinical or pathologic features and outcome. METHODS: Samples from patients with advanced UC and correlative clinical data were collected. Genomic imbalances were investigated by array comparative genomic hybridization (aCGH). ALK gene status was evaluated by fluorescence in situ hybridization (FISH). ALK expression was assessed by immunohistochemistry (IHC) and high-throughput mutation analysis with Oncomap 3 platform. Next generation sequencing was performed using Illumina Genome Analyzer IIx, and Illumina HiSeq 2000 in the FISH positive case. RESULTS: 70 of 96 patients had tissue available for all the tests performed. Arm level copy number gains at chromosome 2 were identified in 17 (24%) patients. Minor copy number alterations (CNAs) in the proximity of ALK locus were found in 3 patients by aCGH. By FISH analysis, one of these samples had a deletion of the 5'ALK. Whole genome next generation sequencing was inconclusive to confirm the deletion at the level of the ALK gene at the coverage level used. We did not observe an association between ALK CNA and overall survival, ECOG PS, or development of visceral disease. CONCLUSIONS: ALK genomic alterations are rare and probably without prognostic implications in UC. The potential for testing ALK inhibitors in UC merits further investigation but might be restricted to the identification of an enriched population.

Epithelial to mesenchymal transition markers are associated with an increased metastatic risk in primary cutaneous squamous cell carcinomas but are attenuated in lymph node metastases.

BACKGROUND: Cutaneous squamous cell carcinoma (cSCC) is the second most common malignancy in humans and approximately 5% metastasize, usually to regional lymph nodes. Epithelial to mesenchymal transition (EMT) is a process involving loss of intercellular adhesion, acquisition of a mesenchymal phenotype and enhanced migratory potential; epithelial markers, such as E-cadherin, are down-regulated and mesenchymal proteins (Vimentin), increased. OBJECTIVE: To investigate the expression of EMT markers in metastatic SCC (MSCC) and their corresponding metastases, and to correlate them with clinico-pathological factors associated with an increased risk of metastasis. METHODS: We performed a retrospective study that included 146 cSCC samples (51 primary non-metastatic, 56 primary metastatic, 39 lymphatic metastases). Immunohistochemistry for E-cadherin, Vimentin, Snail, beta-catenin, Twist, Zeb1 and Podoplanin was performed. RESULTS: Loss of membranous E-cadherin was observed in 77% cSCCs, with no differences between MSCC and non-MSCC. Among the transcriptional factors controlling EMT, no significant Snail1 expression was detected. Twist, Zeb1, Vimentin, beta-catenin and Podoplanin were significantly overexpressed in MSCCs. Twist ectopic expression in SCC13 cells induced Zeb1, Vimentin and Podoplanin expression and E-cadherin delocalization. These changes resulted in a scattered migration pattern in vitro. Expression of EMT markers was decreased in the metastases when compared with the corresponding primary tumors. CONCLUSION: These results suggest that a partial EMT, characterized by the expression of Twist but without a total E-cadherin depletion, is involved in the acquisition of invasive traits by cSCC, but the process is downregulated in lymph node metastases.

D2-40 immunohistochemical overexpression in cutaneous squamous cell carcinomas: a marker of metastatic risk.

BACKGROUND: Approximately 4% of cutaneous squamous cell carcinomas (cSCCs) develop lymphatic metastases. The value of lymphatic endothelial markers to enhance the detection of lymphatic tumor invasion in cSCC has not been assessed previously. OBJECTIVE: We sought to evaluate the use of the antibody D2-40, a podoplanin immunohistochemical marker, to identify tumor lymph vessel invasion in cSCC and to assess its expression in tumor cells. METHODS: This was a retrospective case-control study. A series of 101 cSCC, including 51 cases that developed lymphatic metastatic spread (metastasizing cSCC [MSCC]) and 50 cases that resolved definitely after surgical excision (non-MSCC) were included in the study. Lymph vessel invasion using D2-40 was evaluated on all primary biopsy specimens. The percentage of tumor cells showing D2-40 positivity and intensity scoring were recorded. All the immunohistochemical findings were correlated with the clinicopathological features. RESULTS: Lymph vessel invasion was observed in 8% of non-MSCCs and in 25.5% of MSCCs (P = .031). D2-40 expression was significantly increased, both in intensity (odds ratio 4.42 for intensity ++/+++) and in area (odds ratio 2.29 for area >10%), in MSCC when compared with non-MSCC. Interestingly, almost half (49%) of the MSCC had moderate to intense D2-40 positivity compared with 16% of non-MSCC. D2-40 immunohistochemical expression was increased in tumors with an infiltrative pattern of extension. In the multivariate analysis, histologically poorly differentiated tumors, recurrent lesions, and cSCC showing D2-40 overexpression (in intensity) were significantly associated with lymphatic metastases development (odds ratios 15.67, 14.72, and 6.07, respectively). LIMITATIONS: This was a retrospective study. CONCLUSION: The expression of podoplanin associates with high metastatic risk in cSCC.

Diets high in corn oil or extra-virgin olive oil provided from weaning advance sexual maturation and differentially modify susceptibility to mammary carcinogenesis in female rats.

Based on the importance of early-life events in breast cancer risk, we have investigated the effects of high-fat diets on maturation, mammary gland development, and its susceptibility to transformation. Female Sprague-Dawley rats were fed a lowfat (LF), high corn oil (HCO), or high extra-virgin olive oil (HOO) diet from weaning and gavaged with 7,12-dimethylbenz[a]anthracene. Body weight and mass increased in the HCO group compared to the LF group. The vaginal opening was advanced in both high-fat groups, especially in the HCO group. This HCO group also had increased body weight around puberty, more corpora lutea at post-puberty, and tended to have higher kisspeptin levels in the hypothalamus. Both high-fat diets induced subtle modifications in the morphology of the mammary gland, with no changes on ß-casein or hormone receptors expression in the gland. The HCO diet had a clearly stimulating effect of carcinogenesis, inducing the earliest appearance of tumors and the highest tumor incidence and yield, whereas the HOO diet seemed to have a weak enhancing effect, increasing tumor yield. Our data suggest a strong influence of the HCO diet in sexual maturation and mammary cancer risk, while rats fed the HOO diet were more similar to the controls.

High corn oil and extra virgin olive oil diets and experimental mammary carcinogenesis: clinicopathological and immunohistochemical p21Ha-Ras expression study.

Dietary lipids have a role in the aetiology of breast cancer, acting at several cellular levels. We investigated the effects of a high corn oil and a high extra virgin olive oil diet on the clinical and histopathological characteristics of rat dimethylbenz(α)anthracene-induced mammary carcinogenesis and on the expression of p21Ha-Ras, detected by immunohistochemistry, in one experimental series including a low-fat corn oil diet (LFCO) and two high-fat diet groups: HFCO(P), rich in corn oil, and HFOO(P), rich in extra virgin olive oil. Whereas the high corn oil diet tended to reduce latency time, to raise tumour incidence and to increase total tumour yield, the high extra virgin olive oil diet led to a latency time similar to that of LFCO and to a lower tumour incidence than HFCO(P) and lower total tumour yield, even than LFCO. HFCO(P) tumours displayed a higher histological grade and profile than LFCO tumours, while adenocarcinomas in HFOO(P) were similar to LFCO ones. Although no significant differences in p21Ha-Ras expression among dietary groups was found, we detected a significant p21Ha-Ras decreasing expression as grade increased, in groups LFCO and HFCO(P). HFOO(P) tumours exhibited a higher staining in high-grade carcinomas compared to the similar malignant tumours of the two other dietary groups. These data suggest that dietary lipids influence the clinical behaviour and the morphological malignancy of the experimental mammary carcinogenesis, according to the type of fat, without altering p21Ha-Ras expression. Nevertheless, this expression could be affected by the malignancy of tumours, probably through a post-translational event.

Differential expression of H19 and vitamin D3 upregulated protein 1 as a mechanism of the modulatory effects of high virgin olive oil and high corn oil diets on experimental mammary tumours.

Dietary lipids have a role in the aetiology of breast cancer. We have reported earlier that a high corn oil diet downregulates H19 and vitamin D3 upregulated protein 1 (VDUP1) messenger RNA (mRNA) expression in rat dimethylbenz (alpha) anthracene-induced mammary adenocarcinomas in comparison with the control low-fat diet, this effect being associated with a higher degree of tumour malignancy. This result was compatible with the stimulating effect of this diet. In this study we have investigated the influence of a high extra virgin olive diet on H19 and VDUP1 mRNA and/or protein expression. We have shown earlier that this high-fat diet confers to the tumours a more benign phenotype in accordance with its potential protective effect on mammary cancer. We have also analysed the effects on the mRNA and protein expression of insulin-like growth factor-2 , in close relation with H19, and the expression and activity of the thioredoxin protein, negatively regulated by VDUP1. mRNA and protein expression were analysed by chemiluminescent northern blot and western blot, respectively. Thioredoxin activity was determined by the insulin-reducing assay. The results showed that the high olive oil diet does not change the tumour expression of H19 and VDUP1. Moreover, tumours from the animals fed this diet displayed higher levels of the insulin-like growth factor-2 mRNAs, which are related to a higher rate of degradation or a lower traducibility. Finally, tumour expression and activity levels of thioredoxin-1 protein did not change irrespective of the diet. These results suggest that the differential effects of high olive oil and high corn oil diets on mammary cancer are exerted by means of a different, specific influence on gene expression.

Molecular mechanisms of the effects of olive oil and other dietary lipids on cancer.

Cancer is one of the main causes of mortality worldwide. Geographical differences in incidence rates suggest a key effect of environmental factors, especially diet, in its aetiology. Epidemiologic and experimental studies have found a role of dietary lipids in cancer, particularly breast, colorectal, and prostate cancers. Their incidence in the Mediterranean countries, where the main source of fat is olive oil, is lower than in other areas of the world. Human studies about the effects of dietary lipids are little conclusive, probably due to methodological issues. On the other hand, experimental data have clearly demonstrated that the influence of dietary fats on cancer depends on the quantity and the type of lipids. Whereas a high intake of n-6 PUFA and saturated fat has tumor-enhancing effects, n-3 PUFA, conjugated linoleic acid and gamma-linolenic acid have inhibitory effects. Data regarding MUFA have not always been conclusive, but high olive oil diets seem to have protective effects. Such effects can be due to oleic acid, the main MUFA in olive oil, and to certain minor compounds such as squalene and phenolic compounds. This work aims to review the current knowledge about the relationship between dietary lipids and cancer, with a special emphasis on olive oil, and the molecular mechanisms underlying these effects: modifications on the carcinogenesis stages, hormonal status, cell membrane structure and function, signal transduction pathways, gene expression, and immune system.

High-fat corn oil diet promotes the development of high histologic grade rat DMBA-induced mammary adenocarcinomas, while high olive oil diet does not.

Effects of a high corn oil and a high olive oil diet on the histopathologic characteristics of rat dimethylbenz(alpha)anthracene-induced mammary adenocarcinomas were investigated in comparison with those of a control low-fat diet. Two experimental series (A and B) studied the influence of a high corn oil diet on the initiation and the promotion of mammary carcinogenesis, while another one (C) assessed the effects of the two dietary lipids on the promotion. Nine parameters have been analyzed and a new histologic grading method, adapted to rat tumors, has been applied in each carcinoma. High corn oil diets, particularly when acting as promoters, associated with higher-grade carcinomas than control (p < 0.05) and high olive oil groups. Stromal invasion and tumoral necrosis were more prominent and a prevailing cribriform pattern was observed (p < 0.05). High olive oil diet adenocarcinomas exhibited a predominantly low histologic grade and few necrotic and invasive areas, similar to the control, and they presented the highest percentage of papillary areas. Lymphoplasmacytic and mast cell infiltration were also influenced by the dietary lipids. Thus, high corn oil diet adenocarcinomas presented a higher degree of morphological malignancy than control and high olive oil tumors, which is in line with the greater clinical malignancy described in rats from the former group and the non-promoting effect of the high olive oil diet. As far as we are concerned, a similar histopathologic approach of the effects of the dietary lipids on experimental breast cancer has not been carried out up to now.

Identification of novel differentially expressed genes by the effect of a high-fat n-6 diet in experimental breast cancer.

In previous studies, we demonstrated that high corn oil diets promote the development of 7,12-dimethylbenz(alpha)anthracene (DMBA)-induced mammary tumors. In this study, we have investigated whether modulation of gene expression is one of the mechanisms by which this high-fat diet exerts such effects. Female Sprague-Dawley rats were induced with DMBA and fed normolipidic (3% corn oil) or high-fat (20% corn oil) diet. Screening of genes differentially expressed in adenocarcinomas from the high corn oil diet group compared to the control diet group was performed with cDNA microarrays. The resulting six upregulated and nine downregulated genes were validated by Northern blot and/or reverse transcription (RT)-polymerase chain reaction (PCR). Further investigation in a higher number of adenocarcinomas showed that in the high-fat n-6 diet group, where the tumor phenotype was verified to be more aggressive, the expression of submaxillary gland alpha-2u globulin, vitamin D(3)-upregulated protein 1 (VDUP1), H19, and the unknown function gene that codifies the expressed sequence tag (EST)-Rn.32385 was significantly decreased in comparison with the control group (C). These results, together with the fact that VDUP1, H19, and this globulin have been associated with cell proliferation and differentiation, open a new line of research about how the underexpression of these genes contributes to the stimulating effect of a high corn oil diet on experimental mammary carcinogenesis.

Effects of a high olive oil diet on the clinical behavior and histopathological features of rat DMBA-induced mammary tumors compared with a high corn oil diet.

Effects of a high virgin olive oil diet on the promotion stage of dimethylbenz(alpha)anthracene-induced mammary carcinogenesis in rats were investigated in comparison with those of a high corn oil diet. Animals were randomly placed into 4 groups: control, fed a normolipidic control diet (3% corn oil); M, fed a high corn oil diet (20%); O, fed a high olive oil diet (3% corn oil plus 17% olive oil); and MO, fed the high olive oil diet after 33 days of high corn oil diet. Whereas the high corn oil diet clearly stimulated the mammary carcinogenesis, reducing the latency time and increasing the tumor incidence, multiplicity and volume, the high olive oil diet led to a lower tumor incidence than in the former group, a latency time similar to that of the control and lower tumor multiplicity and volume even than in the control group. Moreover, the histopathological features of the adenocarcinomas in olive oil groups were compatible with a greater degree of differentiation. These data suggest that the high virgin olive oil diet would have acted as a negative modulator of the experimental mammary carcinogenesis conferring to the tumors a more benign clinical behavior and a lower histopathological malignancy in comparison with the control and high corn oil diets.

Histopathologic characterization of mammary neoplastic lesions induced with 7,12 dimethylbenz(alpha)anthracene in the rat: a comparative analysis with human breast tumors.

CONTEXT: The dimethylbenz(alpha)anthracene (DMBA) breast cancer model induced in the rat is used for the study of mammary carcinogenesis because it closely mimics human breast disease. OBJECTIVE: To analyze the histopathologic features of mammary carcinomas induced in the DMBA experimental model, in a manner similar to that used in human pathology, to allow a comparative analysis between both systems. DESIGN: Three experimental series of 20 animals were used. At 53 days of age, a single dose of 5 mg of DMBA per rat was given. Mammary tumors were collected when the rats were killed. Several histopathologic parameters were studied. For grading, the parameters described in the modified Scarff-Bloom-Richardson scheme were used, adapted to rat mammary tumors. RESULTS: More than 50% of the carcinomas presented a pattern grade I, a nuclear grade I or II, and fewer than 10 mitoses/10 high-power fields (P <.05). Although the tumors were generally well differentiated, they showed a range of differentiation. More than 85% of carcinomas did not display tumoral necrosis (P <.05). This feature was observed mostly in high-grade carcinomas. There was no or scanty lymphoplasmacytic infiltration in more than 70% of carcinomas (P <.05). The degree of infiltration increased with the histologic grade. Microcalcifications were found rarely (P <.05). The carcinomas exhibited a mixed structural pattern, most with a predominant cribriform pattern (P <.05). No or light (+) stromal response was seen in most cases (P <.05). Some carcinomas, especially when poorly differentiated, presented a desmoplastic reaction. Most carcinomas presented scanty mast cell infiltration (P <.05), no features of secretion (P <.05), and absence of microcribriform pattern (P <.05). These features were seen more often in low-grade carcinomas. CONCLUSIONS: Despite the presence of some structural differences, rat mammary adenocarcinomas and the most common human breast carcinomas share several morphologic similarities. Moreover, some features could be related to the aggressive behavior of the tumor. The analysis carried out in this study, similar to that done in human pathology, allows a more extensive understanding of mammary tumors in rats, as well as a more accurate use of this animal model, and has made it possible to develop an innovative classification of rat mammary lesions.

Deregulated expression of the PCPH proto-oncogene in rat mammary tumors induced with 7,12-dimethylbenz[a]anthracene.

The PCPH proto-oncogene was identified by its frequent activation in Syrian hamster fetal cells exposed to 3-methylcholanthrene. We previously isolated human PCPH cDNA and studied its expression in normal human tissues. We report herein the pattern of PCPH expression in normal rat tissues. Each tissue expressed one major PCPH polypeptide that varied in molecular mass in different tissues. Normal mammary gland expressed a single PCPH polypeptide of 27 kDa. This PCPH form also was expressed in lactating mammary glands but at significantly greater levels. These results suggest the existence of tissue-specific regulatory mechanisms for PCPH expression that may be influenced by the differentiation stage. Our previous studies on the involvement of PCPH in human cancer showed that human breast tumor cell lines have frequent alterations in PCPH, including multiple PCPH polypeptide forms that are not expressed in normal cells. These cell lines also have frequent loss of a 27-kDa form identified as the only PCPH polypeptide expressed by normal human breast epithelial cells. In this study, we found that these same alterations occurred in vivo during mammary carcinogenesis in Sprague-Dawley rats treated with 7,12-dimethylbenz[a]anthracene, in both benign and malignant tumors, indicating that stable changes in PCPH expression took place early in the neoplastic process. Results showed that this experimental system is relevant to human breast carcinogenesis and provides an excellent model to study the molecular basis of the regulation of PCPH expression during normal differentiation and pathologic stages of neoplasia of the mammary gland and to analyze the role of PCPH in the carcinogenic process. Furthermore, the detection of atypical PCPH polypeptides in tumors suggests that PCPH immunodetection may be applied as a diagnostic tool for the early identification of neoplastic breast epithelial cells.