The Expression Of PDCD5 In Endometrioid Endometrial Carcinoma And The Correlations With Clinicopathologic Parameters

Objective:Endometrial cancer is one of the most common malignancies in female reproductive system.Epidemiologic studies show that some risk factors,including advanced age,early menarche,late menopause,nulliparity,long-term use of estrogen,obesity and diabetes,are associated with an increased risk of endometrial cancer.The vast majority of endometrial cancers are carcinomas which originate from the single layer of epithelial cells.Endometrial carcinomas are broadly organized into two categories.Type ? and Type ?,based on clinical features and pathogenesis.Type ?endometrial carcinomas occur most commonly before and around the time of menopause,and represent 75-90%of endometrial cancer.They are often endometrioid carcinomas,estrogen-dependent,and have a favorable treatment outcome.Type ? endometrial carcinomas usually occur in older,post-menopausal people.They are often non-endometrioid carcinomas,estrogen-independent and carry a poorer prognosis.Nowadays,numerous tumor suppressor genes and oncogenes,such as PTEN and K-ras have been reported to be involved in the development of endometrial cancer.Programmed cell death 5(PDCD5)is a novel apoptosis accelerating gene which was first identified from the leukaemic cell clone TF-1 cells undergoing apoptosis in Human Disease Gene Center of Peking University.Therefore,it is also called TF-1 cell apoptosis-related gene 19(TFAR19).It has been reported that PDCD5 promotes DNA damage-induced apoptosis by interacting with Tip60(a histone acetyltransferase),and PDCD5 phosphorylation induced by a multifunctional kinase CK2 is an important process for its apoptotic potential.The functions of PDCD5 are also related to tumor suppressor gene P53.Park et al.reported YY1-associated factor 2(YAF2)interacts with PDCD5 and promotes TP53-mediated genotoxic stress response via stabilization of PDCD5.OTU deubiquitinase(OTUD5)binds to PDCD5 in response to etoposide treatment and effectively mediates the sequential activation of both PDCD5 and P53.Xu et al.found that PDCD5 interacts with p53 and functions as a positive regulator in the p53 pathway.Choi et al.demonstrated that PDCD5 selectively mediates HDAC3 dissociation from p53,which induces HDAC3 cleavage and ubiquitin-dependent proteasomal degradation.Cui et al.suggested that the expression of PDCD5 is negatively regulated by DNAJB1 and DNAJB1 targets PDCD5 to suppress p53-dependent apoptosis of cancer cells.The studies have confirmed that PDCD5 also suppresses tumorigenesis by inhibiting the Ras/Raf/MEK/MRK signaling pathway in the human osteosarcoma cell line MG-63 and adenovirus carrying PDCD5 gene exerts potent antitumor efficacy on common human leukemic cell lines.In addition,the downregulation of PDCD5 has been observed in multiple types of cancers,such as breast cancer,gastric cancer,hepatocellular carcinoma,acute and chronic myeloid leukemia,glioma and laryngeal squamous cell carcinoma and correlates with tumor progression andprognosis.These findings suggest that apoptosis related gene PDCD5 could be acted as tumor suppressor gene and play important roles in the pathogenesis of cancers.However,the expression of PDCD5 and its clinical significance in endometrial cancer have not been fully elucidated.In the present study,we investigated the levels of PDCD5 expression by qRT-PCR,western blot,immunohistochemistry and immunocytochemistry in endometrioid endometrial carcinoma and control endometrium tissues,as well as control endometrial glandular epithelial cells and human endometrial cancer cell line KLE.Furthermore,we analyzed the associations of PDCD5 expression with clinical and pathological characteristics of patients with endometrioid endometrial carcinoma,and preliminarily investigate the role of PDCD5 in occurrence and progression of endometrioid endometrial carcinoma.Methods:1.qRT-PCR was used to detect the expression levels of PDCD5 mRNA in control endometrium and endometrioid endometrial carcinoma tissues.2.Western blot was used to detect the expression levels of PDCD5 in control endometrium and endometrioid endometrial carcinoma tissues.3.Immunohistochemistry(IHC)technique was used to detect the expression levels of PDCD5 in control endometrium and endometrioid endometrial carcinoma tissues.4.Immunocytochemistry(ICC)technique was used to detect the expression levels of PDCD5 in control endometrial glandular epithelial cells and human endometrial cancer cell line KLE.5.Chi2 test analysis was used to analyze the relationship between PDCD5 expression and clinicopathological parameters of patients with endometrial cancer.Results:1.The expression levels of PDCD5 mRNA in control endometrium and endometrioid endometrial carcinoma tissues detected by qRT-PCRWe detected PDCD5 mRNA expression in 17 control endometrium and 16 freshly frozen endometrioid endometrial carcinoma tissues using qRT-PCR.The results showed that there were no significant differences in PDCD5 mRNA expression between control endometrium and endometrioid endometrial carcinoma tissues(P>0.05).2.The expression levels of PDCD5 protein in control endometrium and endometrioid endometrial carcinoma tissues detected by western blotWe detected the levels of PDCD5 protein in 17 control endometrium and 16 freshly frozen endometrioid endometrial carcinoma tissues using western blot.The data showed that the expression of PDCD5 protein in endometrioid endometrial carcinoma tissues was significantly lower than that in control endometrium(P<0.001),which was inconsistent with the results of qRT-PCR..3.The expression levels of PDCD5 protein in control endometrium and endometrioid endometrial carcinoma tissues detected by IHC(1)The results from IHC revealed PDCD5 protein was mainly located in the cytoplasm of the control endometrial glandular cells or endometrioid endometrial carcinoma cells,and there was also a low level of PDCD5 expression in the nuclei of these cells.(2)The levels of PDCD5 protein were significantly decreased in endometrioid endometrial carcinoma tissues compared with control endometrium(P<0.01).(3)There were no significant differences in PDCD5 expression between proliferative phase and secretory phase of the 53 cases of control endometrium(P>0.05).(4)PDCD5 protein expression was significantly decreased in middle-low differentiation of endometrioid endometrial carcinoma tissues compared with control endometrium(P<0.001);There was no obvious difference between high differentiation of endometrioid endometrial carcinoma tissues and control endometrium.4.The expression of PDCD5 protein in control endometrial glandular cells and human endometrial carcinoma cell line KLE.(1)The glandular epithelial cells expressed cytokeratin and endometrial stromal cells expressed vimentin.(2)PDCD5 positive staining was mainly located in the cytoplasm of control endometrial glandular epithelial cells and KLE cells,and weak PDCD5 expression was also found in the nuclei of the above cells.The PDCD5 protein expression in KLE cells was weaker than that in control endometrial glandular epithelial cells.5.The associations of PDCD5 protein expression in endometrioid endometrial carcinoma tissues with clinicopathologic parameters of patientsThere were no significant correlations between PDCD5 protein levels and age,myometrial invasion.FIGO stage,estrogen receptor or progestin receptor.However,we found that the expression of PDCD5 was significantly associated with the degree of tumor differentiation(P<0.05).PDCD5 protein levels were decreased in middle-low differentiation of endometrioid endometrial carcinoma samples compared with high differentiation of endometrioid endometrial carcinoma samples(P<0.05),which suggested that PDCD5 expression might be correlated with the development and progression of endometrioid endometrial carcinoma.Conclusion:1.There were no significant differences in PDCD5 mRNA expression between endometrioid endometrial carcinoma tissues and control endometrium,and the expression of PDCD5 protein in endometrioid endometrial carcinoma tissues was significantly lower than that in control endometrium,which suggested that PDCD5 may have post-transcriptional regulation in endometrioid endometrial carcinoma.2.PDCD5 expression has no significant difference between the proliferative phase and secretory phase of the endometrium,which suggested that PDCD5 expression may not be regulated by ovarian hormones.3.The expression of PDCD5 was significantly associated with the degree of tumor differentiation,which suggested that PDCD5 expression might have an important role in the development and progression of endometrioid endometrial carcinoma and might contribute to the improvement of prognosis.Originality:1.Our study is the first to report that PDCD5 protein was reduced in endometrioid endometrial carcinoma tissues and its levels was associated with the degree of tumor differentiation.2.Our results suggest that PDCD5 may play an important role in the development and progression of endometrioid endometrial carcinoma and provide a new target for diagnosis and treatment of endometrioid endometrial carcinoma in the futureLimitation:All of our results are based on detection of clinical specimens and cells,lacking confirmation by expriments in vivo and vitro,and the mechnisms of PDCD5 's role in endometrioid endometrial carcinoma remain to be further discussed.