Expression of SATB1, MTI/II and Ki-67 in Mycosis Fungoides

A genome organizer protein, special AT-rich sequence binding protein 1, (SATB1), was recently shown to play an important role in the development and spread of various malignancies. Metallothioneins I and II (MTI/II) are multifunctional proteins involved, among others, in cell proliferation and apoptosis resistance in tumors. The role and relevance of these factors in mycosis fungoides (MF), the most common primary cutaneous T-cell lymphoma, is not fully understood. The aim of the present analysis was to evaluate the expression and potential correlation of SATB1, MTI/II and Ki-67 with clinicopathological data in MF.

We performed immunohistochemical analysis for SATB1, MTI/II and Ki-67 on 90 cases of MF and 19 controls (chronic benign dermatoses). The expression of SATB1 and Ki-67 was analyzed in cancer cell nuclei, whereas nuclear and cytoplasmic expressions of MTI/II were scored separately (nMT, cMT; respectively).

We recorded a significantly higher expression of SATB1 and cMT in MF compared to the control group (p<0.002, p=0.04, respectively, Student's t-test). We also noted significant differences in the mean (±SD) expression of nMT and cMT in advanced MF compared to early MF, (1.4±1.3 vs. 0.9±0.9, 4.1±3.8 vs. 2.5±2.9, respectively; p=0.04 for both). Similarly, Ki-67 expression was significantly higher in advanced MF (p<0.01). The expression of SATB1, cMT and Ki-67 was significantly higher in more infiltrating skin lesions (p<0.001, p=0.08 and p<0.001, respectively). Regarding extracutaneous involvement, a higher expression of SATB1, nMT, cMT and Ki-67 was found in patients with clinical or histological involvement of lymph nodes (N1-3 vs. N0) (p<0.001, p=0.002, p<0.001 and p=0.1, respectively). A marked correlation was observed between SATB1 and Ki-67 (Spearman correlation test: r=0.53, p<0.001). No associations between SATB1, nMT and cMT expression and demographic data nor overall survival were found.

Our study provides data on the differences in the expression of SATB1 and cMT regarding differential diagnosis of MF and tumor-node-metastasis-blood staging. Additionally, our report documented significantly different expression levels of MTI/II and Ki-67 according to the advancement of the disease. In view of these data, the role of studied factors in the development of this type of cutaneous T-cell lymphoma is postulated. Our results indicate that both SATB1 and MTI/II may be of diagnostic value, but our study revealed no prognostic significance; however, given the small number of reports focusing on this topic, further studies are required.