XBP1 promotes tumor invasion and is associated with poor prognosis in oral squamous cell carcinoma.

ABSTRACT

X­box­binding protein 1 (XBP1) contributes to various types of cancer including breast, bladder cancer and esophageal squamous cell carcinoma. The aim of the study was to examine the metastatic role of XBP1 in oral squamous cell carcinoma (OSCC), and identify possible downstream molecules. Immunohistochemical staining was conducted on tissue microarrays comprising 96 OSCC cases to determine the expression level of XBP1 and analyze its association with metastasis, clinicopathological characteristics and survival prognosis. Compared with the adjacent normal tissues of OSCC, the expression of XBP1 was significantly increased in the tumor center and front area, and lymph nodes metastases (P<0.05). A relatively high XBP1 expression was associated with histological grades (P<0.05), advanced clinical stages (P<0.05), unfavorable 5­year survival (P=0.027). Suppressed XBP1 expression caused a significant reduction of cell invasion capability (P<0.05). AXL and the downstream molecules, such as PI3K, MMP1, MMP3, and uPA were significantly suppressed when XBP1 expression was inhibited in OSCC cells. Once XBP1 was activated by Thapsigargin, AXL expression was restored. Moreover, aberrant AXL expression was associated with XBP1 overexpression in OSCC tissues (P<0.05). In conclusion, XBP1 is a potential target that is relevant to suppressing cell invasion and is associated with patient prognosis in OSCC.