Title : Variable expression of ABCB5 in skin mycosis fungoides
Abstract:
Mycosis Fungoides (MF) is a primary cutaneous T-cell lymphoma of the non-Hodgkin type, is classified as the most common skin lymphoma. This lymphoma represents a major therapeutic challenge due to the high prevalence of the multidrug resistance (MDR) phenotype, establishing it as a significant global health concern.
Among the molecular mechanisms underlying chemoresistance, the overexpression of ATP-Binding Cassette (ABC) efflux pumps, such as ABCB5, is particularly prominent. The ABCB5 transporter exerts a dual role in oncogenesis: It functions as a potent drug efflux pump—thereby promoting chemoresistance—and serves as a marker for Tumor-Initiating Cells (TICs).
The lack of predictive markers and limited understanding of fundamental molecular pathways highlight an urgent need for the identification of innovative therapeutic targets and prognostic indicators, particularly those related to drug resistance.
We aimed to investigate the expression of the ABCB5 pump in tissue samples from patients with MF using immunohistochemistry and observed considerable variability among lesions. This finding is consistent with the established intertumoral heterogeneity of mycosis fungoides, which is characterized by neoplastic T cells that accumulate diverse mutations and form distinct subclones within different skin microenvironments.
To this end, we analyzed gene amplification using specific oligonucleotides and evaluated ABCB5 protein expression by Immunohistochemistry (IHC).
In this study, 22 cases of MF were evaluated from clinical and histopathological perspectives by a dermatopathology expert. The expression of the ABCB5 resistance pump, a key factor in multiple cancer types and malignancy-associated features, was also analyzed. Our results revealed variable expression levels among MF cases, indicating that approximately 20% of patients exhibited high ABCB5 expression in tumor lymphocytes infiltrating skin lesions
