Rete testis mucinous adenocarcinoma in a dog

Testicular tumors in commercial boars with infertility: A gross, histologic, and immunohistochemical study

Tumors in boars are uncommon, and testicular tumors even rarer. This study describes the pathological and immunohistochemical characteristics of a case series of testicular tumors in commercial boars with fertility problems. Tumors were detected in 19 of 333 animals (19/333, 5.9%). Macroscopically, tumors were observed in 13 (13/19, 68%) boars, while 6 cases (6/19, 32%) were only detected by microscopic examination. Testicular enlargement was observed in 1 boar, while in the others, tumors were only observed after removal of the scrotal skin or after sectioning of the testis. Histologically, tumors were classified as seminomas (16/19, 84%), mixed germ cell-stromal tumors (2/19, 11%), and B-cell lymphoma (1/19, 5%). Seminomas had 3 different growth patterns: intratubular (6/16, 38%), diffuse (4/16, 25%), and intratubular/diffuse (6/16, 38%). All tumors that were not evident on macroscopic examination were intratubular seminomas. Intratesticular metastases were observed in 2 cases and extratesticular metastases, located in the pampiniform plexus, were observed in 1 case. In 1 seminoma, the rete testis was also involved. By immunohistochemistry, all intratubular seminomas were negative for c-kit, cytokeratin, and vimentin. In diffuse seminomas, c-kit and cytokeratin were also negative, while vimentin showed granular or perinuclear cytoplasmic labeling in some areas. PAX-5 and CD-3 antibodies classified the lymphoma as a B-cell lymphoma. This study suggests that testicular tumors in boars may be more common than previously reported, especially when microscopic examination is performed. It also shows that testicular tumors in pigs are predominantly seminomas.

Canine testicular tumors: An 11-year retrospective study of 358 cases in Moscow Region, Russia

Background and Aim:

Canine testicular tumors are among the most common reproductive tract tumors in male dogs and have been studied in many countries. However, to the best of our knowledge, studies with a large sample size have not been conducted in Russia. This study aimed to provide the latest information on the prevalence of canine testicular tumors in the Veterinary Oncology Scientific Center for Small Animals “Biocontrol” in Moscow, Russia, in 2010-2020 and the characteristics of the affected canine population.

Materials and Methods:

A retrospective review of patients and histological reports was collected and analyzed from 358 dogs with 447 testicular tumors within 11 years.

Results:

The mean age of the affected dogs was 10.4 years, whereas that of dogs with Sertoli cell tumors was 9.4 years p=0.009. This study includes mixed-breed dogs (18.4%), Yorkshire Terriers (8.8%), Labrador Retrievers (7.9%), Golden Retrievers (5.0%), and Fox Terriers (3.4%). The most common tumors were interstitial cell tumors (n=227, 50.8%). In contrast, 107 (23.9%) seminomas, 80 (17.9%) Sertoli cell tumors, 19 (7.4%) mixed germ cell-sex cord-stromal tumors, and 26 (7.6%) testicular tumors developed from cryptorchid testes, which included 16 (61.5%) Sertoli cell tumors, 10 (38.5%) seminomas, and no interstitial cell tumors.

Conclusion:

This study provides baseline information on the prevalence of canine testicular tumors in the described population, including the median age of each tumor type and overrepresented dog breeds. We further found that the most common scrotal testicular tumor was interstitial cell tumor, whereas Sertoli cell tumor was the most common in cryptorchid testicles.

A case of spontaneous rete testis adenoma in a Sprague–Dawley rat

A 104-week-old male CD (SD) rat exhibited enlargement of the left testis. Microscopically, this mass was demarcated from the testis by fibrous connective tissue and characterized by cystic dilatation with single-layered columnar cells and papillary proliferation connected to the solid growth area without clear boundaries. In the solid growth area, cells were dissected into irregular alveolar nests by scant fibrous tissue with small blood vessels. The nuclei of proliferating cells were variable in size and round- to oval-shaped, and their cytoplasm was pale or eosinophilic and sometimes contained vacuoles or eosinophilic granules. Immunohistochemically, the tumor cells were positive for vimentin and cytokeratin (CK) 7. Since CK7 was exclusively positive in the rete testis epithelium of the naïve rat, it was valuable to diagnose this tumor as rete testis-originated. Based on these results and the lack of apparent pleomorphism, mitotic figures, and metastasis, the present case was diagnosed as rete testis adenoma.

Monoclonal antibodies for copper-64 PET dosimetry and radioimmunotherapy

BACKGROUND

We previously described a two-antibody model of (64)Cu radioimmunotherapy to evaluate low-dose, solid-tumor response. This model was designed to test the hypothesis that cellular internalization is critical in causing tumor cell death by mechanisms in addition to radiation damage. The purpose of the present study was to estimate radiation dosimetry for both antibodies (mAbs) using positron emission tomography (PET) imaging, and evaluate the effect of internalization on tumor growth.

RESULTS

Dosimetry was similar between therapy groups. Median time to tumor progression to 1 g ranged from 7 to 12 days for control groups and was 32 days for both treatment groups (p < 0.0001). No statistically significant difference existed between any control group or between the treatment groups.

MATERIAL AND METHODS

In female nude mice bearing LS174T colon carcinoma xenografts, tumor dosimetry was calculated using serial PET images of three mice in each group of either internalizing (64)Cu-labeled DOTA-cBR96 (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) or non-internalizing (64)Cu-labeled DOTA-cT84.66 from 3 to 48 h. For the therapy study, controls (n = 10) received saline, DOTA-cBR96, or DOTA-cT84.66. Treatment animals (n = 9) received 0.890 mCi of (64)Cu-labeled DOTA-cBR96 or 0.710 mCi of (64)Cu-labeled DOTA-cT84.66. Tumors were measured daily.

CONCLUSIONS

PET imaging allows the use of (64)Cu for pre-therapy calculation of tumor dosimetry. In spite of highly similar tumor dosimetry, an internalizing antibody did not improve the outcome of (64)Cu radioimmunotherapy. Radioresistance of this tumor cell line and copper efflux may have confounded the study. Further investigations of the 2 therapeutic efficacy of (64)Cu-labeled mAbs will focus on interaction between (64)Cu and tumor suppressor genes and copper chaperones.

Phylogenetic discordance of human and canine carcinoembryonic antigen (CEA, CEACAM) families, but striking identity of the CEA receptors will impact comparative oncology studies

Comparative oncology aims at speeding up developments for both, human and companion animal cancer patients. Following this line, carcinoembryonic antigen (CEA, CEACAM5) could be a therapeutic target not only for human but also for canine (Canis lupus familiaris; dog) patients. CEACAM5 interacts with CEA-receptor (CEAR) in the cytoplasm of human cancer cells. Our aim was, therefore, to phylogenetically verify the antigenic relationship of CEACAM molecules and CEAR in human and canine cancer.

Anti-human CEACAM5 antibody Col-1, previously being applied for cancer diagnosis in dogs, immunohistochemically reacted to 23 out of 30 canine mammary cancer samples. In immunoblot analyses Col-1 specifically detected human CEACAM5 at 180 kDa in human colon cancer cells HT29, and the canine antigen at 60, 120, or 180 kDa in CF33 and CF41 mammary carcinoma cells as well as in spontaneous mammary tumors. While according to phylogenicity canine CEACAM1 molecules should be most closely related to human CEACAM5, Col-1 did not react with canine CEACAM1, -23, -24, -25, -28 or -30 transfected to canine TLM-1 cells. By flow cytometry the Col-1 target molecule was localized intracellularly in canine CF33 and CF41 cells, in contrast to membranous and cytoplasmic expression of human CEACAM5 in HT29. Col-1 incubation had neither effect on canine nor human cancer cell proliferation. Yet, Col-1 treatment decreased AKT-phosphorylation in canine CF33 cells possibly suggestive of anti-apoptotic function, whereas Col-1 increased AKT-phosphorylation in human HT29 cells. We report further a 99% amino acid similarity of human and canine CEA receptor (CEAR) within the phylogenetic tree. CEAR could be detected in four canine cancer cell lines by immunoblot and intracellularly in 10 out of 10 mammary cancer specimens from dog by immunohistochemistry. Whether the specific canine Col-1 target molecule may as functional analogue to human CEACAM5 act as ligand to canine CEAR, remains to be defined. This study demonstrates the limitations of comparative oncology due to the complex functional evolution of the different CEACAM molecules in humans versus dogs. In contrast, CEAR may be a comprehensive interspecies target for novel cancer therapeutics.

Comparison of rabbit monoclonal and mouse monoclonal antibodies in immunohistochemistry in canine tissues

Rabbit monoclonal (RM) antibodies appear to have higher affinity for antigens than mouse monoclonal (MM) antibodies. However, RM antibodies have not been used in veterinary diagnostic immunohistochemistry. The authors compared reactivities of RM and MM antibodies on formalin-fixed, paraffin-embedded canine tissues, targeting 11 different antigens: CD3, CD79a, calcitonin, calretinin, chromogranin A, COX-2, estrogen receptor, Ki67, progesterone receptor, synaptophysin, and vimentin. Paraffin-embedded tissue sections were processed by 1 of 2 antigen-retrieval methods: 1) proteinase K digestion or 2) steam heat in citrate buffer. An additional set of slides did not receive antigen retrieval. Immunostaining was performed using an automated stainer, and scores were assigned to the different dilutions and antigen-retrieval methods on the basis of staining intensity and number of positive cells. Steam heat was usually the best antigen-retrieval method. The optimal dilution for each antibody was that which resulted in the highest specific staining and the lowest nonspecific (background) staining. The RM or MM antibodies yielded a specific reaction for all antigens examined except calretinin. The RM and MM antibodies yielded a specific reaction for 4 antigens only: COX-2, Ki67, synaptophysin, and vimentin. Three antigens (CD3, chromogranin A, and progesterone receptor) were detected only with RM antibodies, whereas the other 3 (CD79a, calcitonin, estrogen receptor) were detected only with MM antibodies. The results of this study differed from those reported for human tissues by the manufacturers of the antibodies. These results emphasize that, regardless of manufacturers' recommendations, each antibody must be individually standardized and validated before routine use in canine tissues.

Comparative uptakes and biodistributions of internalizing vs. noninternalizing copper-64 radioimmunoconjugates in cell and animal models of colon cancer

Copper-64-labeled monoclonal antibodies (mAbs) have previously demonstrated unexpectedly effective tumor control in rodent models of cancer at relatively low tumor-absorbed radiation doses. This property has been associated with delivery platforms resulting in cellular internalization. The purpose of the present studies was to evaluate the in vitro internalization and in vivo distribution of a two-antibody model of 64Cu radioimmunotherapy (RIT) in the same cell and animal models of cancer. Biodistributions of an internalizing antibody, cBR96, and a noninternalizing antibody, cT84.66, labeled with 64Cu, were obtained in nude mice bearing LS174T colon carcinoma xenografts from 15 min to 48 h. The 64Cu-DOTA-cBR96 conjugate demonstrated rapid tumor uptake, reaching 20.2% ID/g at 3 h and peaking at 35.4% ID/g by 24 h. Tumor accumulation of 64Cu-DOTA-cT84.66 was more gradual, 8.19% ID/g at 3 h and 43.8% ID/g by 24 h, but maximum uptake was not statistically different from 64Cu-DOTA-cBR96. Mouse xenograft dosimetry was estimated to be 1128 rad/mCi (304.9 mGy/MBq) for 64Cu-DOTA-cBR96 and 1409 rad/mCi (380.5 mGy/MBq) for 64Cu-DOTA-cT84.66. In LS174T cells, internalized radioactivity increased by a factor of 3.8 over 4 h for 64Cu-DOTA-cBR96, but remained unchanged 64Cu-DOTA-cT84.66. When normalized to uptake at 1 h, cellular efflux of 64Cu was essentially identical for both mAbs. The biodistributions and tumor dosimetry of these internalizing and noninternalizing radiolabeled mAbs were sufficiently similar for direct comparison of the therapeutic efficacies of low doses of 64Cu RIT agents in the same animal model of cancer.

Immunohistochemical expression of calretinin in canine testicular tumours and normal canine testicular tissue

Calretinin is a calcium-binding protein expressed abundantly in the central and peripheral neural tissues. It has been demonstrated to be a valuable marker in human testicular neoplasia. The immunohistochemical expression of calretinin has been studied in 102 samples of normal (n=25) and three different neoplastic canine testicular tumours (n=77). In normal canine testis, calretinin expression was restricted to Leydig and Sertoli cells of the testis. In tumour tissues, calretinin expression was detected in all tumours investigated (interstitial cell tumours, seminoma, and Sertoli cell tumours), with a cytoplasmic and nuclear pattern of cellular distribution. The present work reports, for the first time, calretinin immunohistochemical expression in normal and neoplastic canine testis.