Fig 2: PLOD2 expression with different clinical characteristics. (a–c) PLOD2 with different differentiations, WPOI and lymph node metastasis in FLCs. (d,e) PLOD2 with different differentiations and WPOI in TCs. Correlation between PLOD2 expression and metastasis (f) or recurrence (g) status in TCs and TILs. * p < 0.05, ** p < 0.01, *** p < 0.001.

Fig 3: Ectopic LH2 overexpression in LH2-low cells augments HNSCC migration and invasion.(A) Evaluation of the doxycycline inducible Tet-On 3G system for inducing LH2 expression. Quantitative real-time PCR analysis of LH2 mRNA levels in UM-SCC-5_PGKTetOn3GTRE3GLH2 cells treated with increasing concentrations of doxycycline for 72 hrs. Representative data of independent biologic replicates are presented as the mean ± SD (4 technical replicates per biologic replicate).(B) Top, UM-SCC-5_PGKTetOn3GTRE3GLH2 cells were treated with the indicated concentrations of doxycycline for 72 h, total protein extracted, and western blot run to validate induced expression at the protein level. This blot is representative of independent biologic replicates. Bottom, quantification of LH2 protein levels. Band intensities were normalized to ß-actin and are shown as the fold change relative to the no doxycycline condition.(C) Wound healing (scratch) assay performed with UM-SCC-5_PGKTetOn3GTRE3GLH2 cells treated +/- 1 µg/mL doxycycline for 72 h. Images were captured every hour for 24 h to quantify rates of wound closure. Representative data of independent biologic replicates are presented as the mean ± SD (3 independent FOV were captured and quantified per biologic replicate; Two-way ANOVA test with Sidak correction, *P < 0.05, **P < 0.01, ***P < 0.001).(D) Transwell invasion assays were performed for UM-SCC-5_PGKTetOn3GTRE3GLH2 cells treated +/- doxycycline using Boyden chambers precoated with Matrigel. Cells were stained with 0.05% crystal violet after 24 h, imaged, and cell invasion quantified. Representative data of independent biologic replicates are presented as the mean ± SD (>5 independent FOV was quantified per biologic replicate; Student's t test, ns = not significant, ****P < 0.0001).

Fig 4: PLOD2 spatial expression in different cell types of OSCC patients. (a) Representative immunohistochemistry (IHC) staining of PLOD2 in tumor cells (TCs), fibroblast-like cells (FLCs), and tumor-infiltrating lymphocytes (TILs). (b) Representative high and low expression of PLOD2 in FLCs and TCs. *** p < 0.001.

Fig 5: Survival analysis results. KM survival curves for OS, DFS, MFS, and RFS of OSCC patients according to the expression of PLOD2 in TCs (a–d) and FLCs (e–h), respectively. TCGA database was used to evaluate the relationships between PLOD2 expression and patient survival. High expression of PLOD2 has poor OS (i) and DFS (j) in HNSCC patients.