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Purpose <p>Pterygium is a common ocular surface disorder strongly associated with ultraviolet (UV) radiation exposure and oxidative stress. Double-strand breaks (DSBs) are among the most deleterious forms of DNA damage, and their repair mainly relies on the non-homologous end joining (NHEJ) pathway, in which the DNA-dependent protein kinase (DNA-PK) complex plays a central role. This study investigated the expression of the DNA-PK complex components—DNA-PKcs, Ku70, and Ku86—in pterygium compared with healthy conjunctiva.</p> Methods <p>Conjunctival tissues were obtained from six patients undergoing surgical excision of recurrent pterygium and 6 age- and sex-matched controls undergoing ocular surgery without surface disease. Protein and transcript expression of DNA-PKcs, Ku70, and Ku86 were assessed by immunofluorescence, Western blotting, and real-time PCR.</p> Results <p>Immunofluorescence revealed markedly reduced DNA-PKcs immunoreactivity in the epithelium of pterygium conjunctiva compared with marked staining in controls. Western blot analysis demonstrated a significant decrease of DNA-PKcs protein, paralleled by a ~ 13-fold reduction of its mRNA. Similarly, Ku70 and Ku86 protein levels were dramatically reduced (by ~ 93.5% and ~ 92.0%, respectively) in pterygium compared with controls.</p> Conclusions <p>This study provides the first evidence of profound down-regulation of the DNA-PK complex in pterygium. The loss of DNA-PKcs and its regulatory subunits Ku70 and Ku86 suggests impaired DSB repair capacity, potentially driven by chronic UV-induced oxidative stress. These alterations may contribute to pterygium pathogenesis and recurrence, highlighting DNA-PK complex proteins as potential biomarkers of disease susceptibility and progression.</p>

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Loss of DNA-PK complex in recurrent pterygium suggests a role for defective double-strand break repair

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月26日

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  • Leonardo Lupacchini,
  • Marco Marenco,
  • Marco Rosina,
  • Fabiana Mallone,
  • Cristiana Mollinari,
  • Angelina Pernazza,
  • Alessandro Lambiase,
  • Daniela Merlo

摘要

Purpose

Pterygium is a common ocular surface disorder strongly associated with ultraviolet (UV) radiation exposure and oxidative stress. Double-strand breaks (DSBs) are among the most deleterious forms of DNA damage, and their repair mainly relies on the non-homologous end joining (NHEJ) pathway, in which the DNA-dependent protein kinase (DNA-PK) complex plays a central role. This study investigated the expression of the DNA-PK complex components—DNA-PKcs, Ku70, and Ku86—in pterygium compared with healthy conjunctiva.

Methods

Conjunctival tissues were obtained from six patients undergoing surgical excision of recurrent pterygium and 6 age- and sex-matched controls undergoing ocular surgery without surface disease. Protein and transcript expression of DNA-PKcs, Ku70, and Ku86 were assessed by immunofluorescence, Western blotting, and real-time PCR.

Results

Immunofluorescence revealed markedly reduced DNA-PKcs immunoreactivity in the epithelium of pterygium conjunctiva compared with marked staining in controls. Western blot analysis demonstrated a significant decrease of DNA-PKcs protein, paralleled by a ~ 13-fold reduction of its mRNA. Similarly, Ku70 and Ku86 protein levels were dramatically reduced (by ~ 93.5% and ~ 92.0%, respectively) in pterygium compared with controls.

Conclusions

This study provides the first evidence of profound down-regulation of the DNA-PK complex in pterygium. The loss of DNA-PKcs and its regulatory subunits Ku70 and Ku86 suggests impaired DSB repair capacity, potentially driven by chronic UV-induced oxidative stress. These alterations may contribute to pterygium pathogenesis and recurrence, highlighting DNA-PK complex proteins as potential biomarkers of disease susceptibility and progression.