Immunohistochemical expression pattern of leukemia inhibitory factor and its receptor may mark a tipping point in the progression of oral cancer.

Oral squamous cell carcinoma (OSCC) is an aggressive cancer with 60% survival rate, high mortality, and morbidity. Leukaemia inhibitory factor (LIF) and its receptor (LIF-R) are involved in the activation of the signal transducer and activator of transcription-3 (STAT3) pathway which has central involvement in the signalling pathways involved in important pathological processes including carcinogenesis and inflammation. STAT3 and its activators have shown prognostic significance in OSCC. The aim is to evaluate the immunohistochemical (IHC) expression of LIF and LIF-R proteins in OSCC. Four tissue microarrays (TMA) including OSCC (n = 95) and normal oral mucosa (NOM; n = 11) as control tissue were used in this study. FIJI software was for semi-quantitative analysis of IHC expression of LIF and LIF-R. Statistical analysis were performed using SPSS. LIF-R was expressed to a significantly higher extent in OSCC compared to NOM (p = 0.02) and LIF was expressed to a significantly higher extent in NOM compared to OSCC (p < 0.001) and in the buccal mucosa compared to the gingiva/alveolar mucosa (p = 0.022) and the lip vermilion (p = 0.17). No other significant differences were found in LIF and LIF-R expression when OSCC were compared according to site, grade, or stage. This is the first study to confirm the expression of LIF in OSCC and NOM. The biphasic lower expression of LIF and higher expression of LIF-R in OSCC may indicate a key point of differentiation between NOM and OSCC. The downregulation of LIF expression may be an indication of promotion towards malignancy.