Objective To investigate the expression of X-box binding protein 1 (XBP1) and programmed death-ligand 1 (PD-L1) in cutaneous malignant melanoma (CMM) and their clinical significance.

Methods Fifty-three patients with CMM and fifty-six patients with pigmented nevus were selected from those admitted to the General Hospital of Ningxia Medical University between January 2017 and July 2023. The expression levels of XBP1 and PD-L1 in malignant melanoma tissues and pigmented nevus tissues were detected using immunohistochemical staining. The relationships between the expression levels of XBP1 and PD-L1 and the clinical characteristics of patients with CMM were then analyzed. Spearman’s analysis was applied to assess the correlation between XBP1 and PD-L1 expression levels in CMM.

Results The expression levels of XBP1 and PD-L1 were significantly higher in CMM tissues than those in pigmented nevus tissues (P<0.05). Elevated XBP1 expression levels in patients with CMM were associated with clinical stages Ⅱ-Ⅳand tumor-infiltrating lymphocytes (TILs) grade 2-3 (P<0.05). Similarly, elevated PD-L1 expression levels in patients with CMM were associated with ulceration of the primary foci, clinical stages Ⅱ-Ⅳ, Clark grades Ⅳ-Ⅴ, and TILs grades 2-3 (P<0.05). Spearman’s analysis demonstrated a positive correlation between XBP1 and PD-L1 expression in CMM (P<0.05).

Conclusions XBP1 and PD-L1 can be used as molecular markers for the diagnosis and evaluation of CMM. Additionally, XBP1 may affect the development of CMM by regulating the expression of PD-L1, thereby altering the tumor microenvironment.