Expression of metallothionein protein relating to proliferative cell index in malignant feline mammary tumors using high throughput tissue microarray technique

Abstract

The present study aimed to examine the relationship between proliferation markers by detecting Ki-67 and proliferative cell nuclear antigen (PCNA) indices, and metallothionein expression, in different histological groups and nuclear grades of malignant feline mammary tumors by using immunohistochemistry and tissue microarray technique. Seventy feline mammary carcinoma (FMC) biopsy specimens were collected to perform tissue microarray (TMA) slide. The immunohistochemical staining was performed on the TMA slides against pancytokeratin (CK19), PCNA, Ki-67 clone MIB, and metallothionein 1 (MT-1) antibodies. The PCNA index showed no significant differences among histological types and nuclear grades, whereas the Ki-67 index showed statistical difference among histological types and malignancy grades (p < 0.05). The pattern of cytoplasmic MT expression was observed in glandular carcinoma cells. The percentage ± SD of MT expression was 44.13 ± 30.24 in tubular adenocarcinomas, 39.29 ± 26.21 in papillary adenocarcinomas, 22.66 ± 17.81 in cribriform carcinomas, and 38.12 ± 30.33 in solid carcinomas. The percentage ± SD of MT expression was 32.68 ± 27.59 in grade I, 37.34 ± 26.37 in grade II, and 43.54 ± 32.97 in grade III. Our study showed that the expression of MT increased with nuclear grade rather than histological subtype. It is suggested that the role of MT in carcinogenesis and tumor progression could be linked to involvement of MT in processes of cell proliferation and differentiation of feline mammary carcinomas.