Open Access

ARTICLE

Altered Expression of UFMylation Pathway Proteins Is Linked with Cancer Stem Cell Features and Aggressive Clinical Phenotype of Head and Neck Cancer

Kristina Vukovic Derfi¹, Marko Tarle^2,3, Koraljka Hat^2,3, Tea Vasiljevic¹, Danko Müller^4,5, Ivica Luksic^2,5, Tanja Matijevic Glavan^1,*
1 Division of Molecular Medicine, Rudjer Boskovic Institute, Zagreb, Croatia
2 Department of Maxillofacial Surgery, Dubrava University Hospital, Zagreb, Croatia
3 School of Dental Medicine, University of Zagreb, Zagreb, Croatia
4 Department of Pathology and Cytology, Dubrava University Hospital, Zagreb, Croatia
5 School of Medicine, University of Zagreb, Zagreb, Croatia
* Corresponding Author: Tanja Matijevic Glavan. Email:

Oncology Research https://doi.org/10.32604/or.2026.083630

Received 07 April 2026; Accepted 18 August 2026; Published online 25 August 2026

Abstract

Objectives: Head and neck squamous cell carcinoma (HNSCC), with oral squamous cell carcinoma (OSCC) comprising approximately 90% of cases, is a highly aggressive cancer characterized by frequent recurrence, therapy resistance, and poor prognosis, all largely attributed to the presence of cancer stem cells (CSCs). The UFMylation pathway, a recently described post-translational modification, has been implicated in the regulation of cancer cell survival, proliferation, and stemness; however, its clinical significance in HNSCC remains poorly understood. In the present study, we aimed to examine the correlation between dysregulated UFMylation components and both the clinical presentation and CSC-related phenotypes in HNSCC. Methods: The expression of UFM1-specific peptidase 2 (UFSP2) protein was evaluated in tumor and normal tissues from 54 oral squamous cell carcinoma (OSCC) patients and correlated with clinicopathological features. The expression of stemness markers, UFMylation-related genes/proteins and UFMylation substrates was also assessed. Functional effects of Ubiquitin-Like Modifier Activating Enzyme 5 (UBA5) inhibition were examined in tumor spheres, including survival, apoptosis, autophagy, and ferroptosis-related markers. Bioinformatic analyses were performed to explore associations between UFMylation proteins, stemness/epithelial–mesenchymal transition (EMT) markers, iron metabolism-related markers, and pathological stage. Results: UFSP2 expression levels varied considerably among tumors, with both overexpression and downregulation consistently associated with advanced OSCC clinical severity. UFSP2-overexpressing cohort exhibited broad up-regulation of stemness markers cluster of differentiation 133 (CD133) and octamer-binding transcription factor 4 (OCT4), whilst UFSP2-downregulated tumors consistently displayed at least one upregulated stemness marker. The most advanced cases demonstrated elevated UFM1-conjugating enzyme 1 (UFC1) and UBA5 levels, typically alongside increased DDRGK domain-containing protein 1 (DDRGK1) and UFMylation substrate expression. UBA5 inhibition demonstrated a distinct, dose-dependent impact on tumor spheres: whereas low concentrations promoted tumor sphere survival, induced autophagy, and upregulated stemness markers, high concentrations significantly impaired sphere viability, triggered ferroptosis, and resulted in total sphere elimination. Bioinformatic analyses further demonstrated tumor-specific correlations between UBA5 and stemness markers, as well as a significant association between the ferroptosis-related gene transferrin receptor 1 (TfR1) and pathological stage in HNSCC. Conclusion: Our findings link a dysregulated UFMylation system to increased stemness, iron metabolic shifts, and aggressive clinical phenotype of HNSCC, highlighting a functional role for UFMylation and ferroptosis-related pathways in HNSCC biology. These results underscore the importance of considering the dose-dependent effects of UBA5 modulation when investigating the consequences of perturbing this pathway.

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Keywords

Autophagy; cancer stem cells; cancer therapy; ferroptosis; head and neck squamous cell carcinoma; UFMylation

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