Poly(A)-specific ribonuclease protein promotes the proliferation, invasion and migration of esophageal cancer cells

Abstract

Background: Bioinformatics analysis showed that the expression of the poly(A)-specific ribonuclease (PARN) gene in gastric cancer, head and neck squamous cell carcinoma, melanoma, cervical cancer and lung squamous cell carcinoma tissues was significantly higher than that in normal tissues and was associated with high stage and poor prognosis. The expression of the PARN gene in esophageal cancer (EC) tissue is also significantly higher than that in normal tissues, but the effect of PARN on the proliferation, migration and invasion of EC cells remains unclear.

Aim: To investigate the relationship between PARN and the proliferation, migration and invasion of EC cells.

Methods: The EC tissues of 91 patients after EC surgery and 63 paired precancerous healthy tissues were collected. PARN mRNA levels were measured using a tissue microarray, and the PARN expression level was evaluated using immunohistochemistry to analyze the relationship between PARN expression and clinicopathologic features as well as the survival and prognosis of patients. In addition, the effects of PARN gene knockout on tumor cell proliferation, invasion and migration were studied by using shRNA during the in vitro culture of EC cell lines Eca-109 and TE-1, and the effects of the PARN gene on tumor growth in vivo were verified by a xenotransplantation nude mice model.

Results: The expression of PARN in EC tissues was higher than that in adjacent normal tissues, and the level of PARN expression was significantly positively correlated with lymphatic metastasis. Patients with high PARN levels had poor overall survival. BIM, IGFBP-5 and p21 levels were significantly increased in the PARN knockout group, while the expression levels of the antiapoptotic proteins Survivin and sTNF-R1 were significantly decreased in the apoptotic antibody array data. In addition, the expression levels of Akt, p-Akt, PIK3CA and CCND1 in the downstream signaling pathway regulating EC progression were significantly decreased. The culture of EC cell lines confirmed that the apoptosis rate of EC cells was significantly increased, the growth and proliferation of tumor cells were significantly inhibited, and the invasion and migration ability of tumor cells were significantly decreased after PARN gene knockout. In vivo experiments of BALB/c nude mice transfected with Eca-109 cells expressing control shRNA (sh-NC) and PARN shRNA (sh-PARN) showed that the tumor volume and weight of nude mice treated with sh-PARN were significantly decreased compared with those of nude mice treated with sh-NC, indicating that PARN knockdown significantly inhibited tumor growth in vivo.

Conclusion: PARN has antiapoptotic effects on EC cells and promotes their proliferation, invasion and migration, which is associated with the development of EC and poor patient prognosis. PARN may become a potential target for the diagnosis, prognosis prediction and treatment of EC.

Keywords: Apoptotic; Esophageal cancer; Phosphatidylinositol 3-kinase/protein kinase B; Poly(A)-specific ribonuclease.