High OCT4 Expression Might Be Associated with an Aggressive Phenotype in Rectal Cancer

Abstract

Rectal cancer (RC) is one of the most common malignant neoplasms, and cancer stem cells (CSCs) of the intestinal tract have been implicated in its origin. The oncofetal protein OCT4 has been linked to neoplastic processes, but its role and clinical significance in RC are unknown. This study investigates the expression of the stem cell marker OCT4 related to clinical-pathological characteristics and its clinical significance in RC patients. The expression level of stem cell marker OCT4 was analyzed in 22 primary rectal tumors by western blot. The association between OCT4 protein expression and the clinical-pathological features of tumors was evaluated by χ² test and Fisher's exact test. We demonstrated that the expression of the stem cell marker OCT4 was observed in tumor tissue but not adjacent non-tumor tissue. High expression of the stem cell marker OCT4 was significantly associated with histological differentiation grade (p = 0.039), tumor invasion level (p = 0.004), lymph node involvement (p = 0.044), tumor-node-metastasis (TNM) stage (p = 0.002), and clinical stage (p = 0.021). These findings suggest that high OCT4 expression is associated with a more aggressive RC phenotype, with a greater likelihood of progression and metastasis. These results shed light on the importance of targeting this CSC marker to attenuate RC progression.

Keywords: OCT4; cancer stem cells; colorectal cancer; oncofetal protein; rectal cancer.

Figure 1

Expression of OCT4 protein in RC tissue and adjacent non-tumor tissue according to the histological differentiation grade and tumor stage. (a) Western blot analysis of OCT4 protein expression according to the histological differentiation grade. (b) Immunoelectrophoretic analysis of OCT4 protein expression according to the histological differentiation grade. (c) Western blot analysis of OCT4 protein expression according to the tumor stage. (d) Immunoelectrophoretic analysis of OCT4 protein expression according to the tumor stage. The expression of GUSB was used as a normalizer. See Supplementary Material for the original image of the Western Blots.

Figure 2

Protein expression levels of OCT4 in rectal tumors. (a) OCT4 expression levels in rectal tumors according to histological differentiation grade. (b) OCT4 expression levels in rectal tumors according to clinical-pathological stage. Results are the ratio of OCT4 expression normalized to GUSB protein levels. Statistical differences between groups were evaluated by two-tailed Student’s t-test.