Figure 3.

SQLE promotes tumorigenic phenotypes and cancer stemness in HNSCC cells through modulating cholesterol homeostasis. a,b) qRT‐PCR and western blot analyses of SQLE mRNA and protein expression in ALDH^high and ALDH^low cells isolated from six HNSCC patients (n = 4). c) Western blot analysis of the impact of SQLE depletion on cancer stem cell‐related marker expression (CD44, BMI‐1, SOX2, and KIF‐4) in ALDH^high and ALDH^low primary HNSCC cells from patient case #1 (Pt. 1) and case #2 (Pt. 2). d,e) In vivo limiting dilution analysis of EpCAM⁺ALDH^high tumor cells from Pt. 1 infected with shCTRL and shSQLE lentiviruses (n = 10). Frequency of tumor‐initiating cells at each injected cell dose is shown. Differences in CSC frequencies calculated using the Extreme Limiting Dilution Analysis (ELDA) software. f,g) Effects of cholesterol repletion (20 µg mL⁻¹) on colony formation potential and cellular apoptosis in SCC‐1^cisR and SCC‐23^cisR cells with SQLE depletion in the presence of cisplatin (n = 4). h) Effects of exogenous cholesterol (20 µg mL⁻¹) on expression of CD44, BMI‐1, SOX2, and KIF‐4 in SCC‐1^cisR and SCC‐23^cisR cells with SQLE depletion and cisplatin treatment. Data were presented as mean ± SD. ***p < 0.001 for Student's t‐test and one‐way ANOVA test.