DIRAS2 promotes the progression of oral leukoplakia via suppressing ferroptosis

Oral leukoplakia (OLK) is the most prevalent potentially malignant oral disorder (OPMD). Ferroptosis, a distinct form of regulated cell death, has recently garnered significant attention in a variety of diseases. DIRAS2 is a member of the DIRAS family within the RAS protein superfamily and is highly expressed in OLK tissues. Nevertheless, the precise mechanism through which DIRAS2 modulates ferroptosis in OLK remains elusive.

Immunohistochemical staining was used to assess the expression of GPX4 in human normal oral mucosa and OLK tissues. DIRAS2 knockdown and control Leuk-1 cell were treated with Erastin to induce ferroptosis, and EDU, Mito Tracker green and MitoSOX probes were utilized to evaluate cell proliferation and mitochondrial changes. Additionally, the expression of ferroptosis-associated proteins and PI3K-AKT pathway in Leuk-1 cells and 4-nitroquinoline-1-oxide (4NQO)-induced DIRAS2^flox/flox mouse and DIRAS2^{flox/flox:Cre+} mouse tongue tissues was examined via western blotting and immunohistochemistry, respectively.

GPX4 was abnormally highly expressed in human OLK tissues than in normal mucosa tissues. Erastin significantly elevated Reactive Oxygen Species (ROS) level in Leuk-1 cells, concurrently downregulating cell proliferation and GPX4, PI3K, AKT and pAKT expression. DIRAS2 knockdown further potentiated Erastin-induced ferroptosis. Additionally, compared with the control group, DIRAS2-knockdown cells presented significant alterations in mitochondrial morphology. Compared to control mice, the expression of GPX4, PI3K, AKT and pAKT in the 4NQO-induced mouse tongue tissues was markedly upregulated. The expression of these proteins in DIRAS2^{flox/flox:Cre +} mouse tongue tissues demonstrated a notable reduction compared with DIRAS2^flox/flox mouse tongue tissues.

DIRAS2 may affect OLK development by repressing ferroptosis through the PI3K/AKT pathway.