Adipocytes promoted anoikis resistance of head and neck cancer cells via overexpressed ITGA5.

Background: Head and neck squamous cell carcinoma (HNSCC) was the sixth most common cancer worldwide. Given the evidence that adipocytes are related to the progression of various cancers, this study explored the internal connection and mechanism between HNSCC and adipocytes.

Methods: Quantitative real-time PCR (qRT-PCR) was used to examine the transfection efficiency of integrin subunit α5 (ITGA5) overexpression plasmid and small interfering RNA of ITGA5 (si-ITGA5). Colony formation assay was employed to detect the colony formation rate of FaDu and SAS cells, while flow cytometry was used to measure cell apoptosis rate. The protein levels of cleaved-caspase-3 (apoptosis marker) and cell adhesion markers (ITGA5, integrin subunit β1 (ITGB1) and cluster of differentiation 44 (CD44)) were analyzed by western blotting. After HNSCC cells and adipocytes were co-cultured, the last three experiments above-mentioned were repeated and Calcein AM/EthD-1 double stain assay was performed to examine anoikis.

Results: Overexpressed ITGA5 enhanced colony formation and inhibited anoikis in HNSCC cells (p < 0 p < .001), while reducing the expression of the apoptosis-related protein and increasing those of adherence-related proteins (p < 0.05). However, si-ITGA5 had the opposite effect. After co-culture of HNSCC cells with adipocytes, cell colony formation was increased, anoikis was inhibited and the expressions of ITGA5 and cell adhesion markers were upregulated (p < 0.05). The effects of HNSCC cells co-cultured with adipocytes on colony formation, anoikis and cell adhesion markers were reversed by ITGA5 silencing (p < 0.01).

Conclusion: Adipocytes promote anoikis resistance of head and neck cancer cells via overexpressed ITGA5.