Expression and Roles of S100A4 in Anaplastic Cells of Canine Mammary Carcinomas.

S100A4 (metastasin), a member of the S100 protein family, was initially identified in metastatic cells and is well established as a marker of aggressive human cancer. However, expression and roles of S100A4 in canine mammary tumors have not been clarified. In this study, expression of S100A4 was examined immunohistochemically in normal, hyperplastic, and neoplastic mammary glands of dogs. In all normal and benign lesions, S100A4 was restricted to a few stromal fibroblasts and inflammatory cells. However, in 7 of 57 (12%) of the malignant tumors examined, cytoplasmic and nuclear expression of S100A4 was observed in epithelial tumor cells and stromal cells. Particularly, the frequency of S100A4-positive anaplastic carcinomas was high (4/8 cases, 50%). Next, we established a novel cell line, named NV-CML, from a S100A4-positive canine mammary carcinoma. The cultured NV-CML cells and the tumors that developed in the immunodeficient mice after subcutaneous injection of the cells maintained the immunophenotype of the original tumor, including S100A4 expression. Using this cell line, we examined the cellular functions of S100A4 using RNA interference. S100A4 expression level in NV-CML cells transfected with small interfering RNA (siRNA) targeting canine S100A4 (siS100A4) was reduced to about one-fifth of those with negative-control siRNA (siNeg). Cell proliferation in WST-8 assay and cell migration in Boyden chamber assay were significantly decreased in siS100A4-transfected cells compared with siNeg-transfected cells. These findings suggest that S100A4 may be related to progression of canine mammary carcinomas via its influence on cell growth and motility.

Laparoscopic-extracorporeal surgery performed with a fixation device for adnexal masses complicating pregnancy: Report of two cases.

The potential complications associated with an adnexal mass discovered during early pregnancy call for surgical treatment. Ideally, surgery is performed after gestational week 12, but uterine expansion after the first trimester makes surgery difficult. We report two pregnancies complicated by adnexal masses for which we used an organ fixation device for safe performance of single-site umbilical laparoscopic surgery. Pelvic magnetic resonance imaging depicted a dichorionic, diamniotic twin pregnancy and 60-mm right adnexal mass in the first patient and bilateral adnexae in the second. All three masses were suspected mature cystic teratomas. Both patients underwent laparoscopic surgery during gestational week 14. With use of an organ fixation device, traction was applied until the mass reached the umbilicus; tumor resection was performed extracorporeally. In the second patient, the second mass was simply aspirated because adhesions were encountered. Our single-site laparoscopic-extracorporeal technique proved to be a safe approach to an otherwise high-risk situation.

Flow cytometric analysis for detection of tumor-initiating cells in feline mammary carcinoma cell lines.

A small population of cells known as tumor-initiating cells (TICs), which have the capacity to self-renew, differentiate, and form tumors at high frequency, has a potential role in tumor initiation, aggression, and recurrence. In human breast cancers, TICs are identified by surface markers, such as CD44 and CD24, and an aldefluor assay based on aldehyde dehydrogenase activity (ALDH(+)) using flow cytometry. However, the usefulness of surface markers CD44 and CD24 and ALDH activity in feline mammary carcinomas remains largely elusive. We attempted to identify CD44(+)CD24(-) and ALDH(+) cells using 8 feline mammary carcinoma cell lines, including FKNp, which was obtained from a primary lesion, and the capacity to generate tumor nodules was analyzed in immunodeficient mice injected with ALDH(+) FKNp-derived cells. The CD44(+)CD24(-) and ALDH(+) cells were detected in all cell lines derived from feline mammary carcinomas. Xenograft transplantation into immunodeficient mice demonstrated that as few as 1 × 10(2) ALDH(+) cells could initiate tumor growth in 1 out of 4 mice, while 1 × 10(3) ALDH(+) cells initiated tumor growth in 5 out of 6 mice. However, 1 × 10(3) ALDH(-) cells failed to initiate tumors in all the tested mice. ALDH(+)-derived tumors contained both ALDH(+) and ALDH(-) cells, indicating that ALDH(+) FKNp-derived cells had higher tumorigenicity than ALDH(-) cells. These results suggest that TICs may exist in feline mammary carcinomas, and further characterization of CD44(+)CD24(-) and ALDH(+) cells is needed to define novel therapies targeted against TICs. This study provides the foundation for elucidating the contribution of TICs in tumorigenesis.