Aberrant TIMELESS expression is associated with poor clinical survival and lymph node metastasis in early-stage cervical carcinoma

Abstract

TIMELESS is a highly conserved protein required for the maintenance of normal mammalian circadian oscillations and for controlling cellular metabolism and proliferation. Recently, TIMELESS was implicated in the tumorigenesis of certain cancers. However, little is known on TIMELESS protein expression and its potential as a prognostic factor in cervical cancer. Here, we investigate TIMELESS expression pattern and its clinicopathological significance in early-stage cervical carcinoma. TIMELESS mRNA and protein expression was evaluated by real-time PCR and western blot analysis in cervical cancer cell lines, a normal cervical cell line, as well as in six pairs of surgically removed cervical cancer and adjacent normal cervical tissues. A total of 189 paraffin-embedded cervical carcinoma specimens were detected and diagnosed by immunohistochemistry (IHC), and the clinical significance of TIMELESS expression was further analyzed. Aberrant TIMELESS mRNA and protein expression were demonstrated in cervical cancer cell lines compared with the normal cervical cell line. TIMELESS mRNA and protein expression were significantly increased in cervical cancer specimens compared with adjacent non-cancerous cervical specimens. TIMELESS protein expression was significantly associated with the age (P=0.011), clinical stage (P<0.001), pelvic lymph node metastasis (P<0.001), squamous cell carcinoma antigen (P=0.003), tumor recurrence (P=0.015), vital status (P<0.001), tumor differentiation grade (P<0.001), property of the surgical margin (P=0.036) and lymphovascular space involvement (P=0.001). Patients with increased TIMELESS protein expression showed strong tendencies to receive postoperative radiotherapy (P=0.002). Upregulation of TIMELESS correlated with poorer overall survival (OS) and disease-free survival (DFS). Univariate and multivariate Cox-regression analyses showed that TIMELESS can be regarded as an independent predictive biomarker for poor clinical outcome for early-stage cervical carcinoma. Our results show that TIMELESS overexpression correlates with pelvic lymph node metastasis, lymphovascular space involvement, as well as unfavorable OS and DFS in human cervical cancer. Therefore, TIMELESS expression may be a potential prognostic biomarker for cervical cancer patients.