Alterations of UHRF family Expression and was regulated by High Risk Type HPV16 in Uterine Cervical Cancer.

The altered protein expression of inverted CCAAT box-binding protein of 90 kDa/ubiquitin-like with PHD and RING finger domains 1 (ICBP90/UHRF1), and Np95-like ring finger protein (NIRF)/UHRF2, which belong to the ubiquitin-like with PHD and RING finger domains (UHRF) family, is linked to tumor malignancy and the progression of various cancers. In this study, we analyzed the UHRF family expression in cervical cancers, and it's regulation by human papillomavirus (HPV). Western blotting was performed to analyze protein expression in cervical cancer cell lines. Immunohistochemical analysis were used to investigate the expression of UHRF family and MIB-1 in cervical cancer tissues. Transfection were done for analyze the relationship between UHRF family and HPVs. We showed that NIRF expression was decreased and ICBP90 expression was increased in cervical cancers compared to normal counterparts. Western blotting also showed that NIRF expression was quite low levels, but ICBP90 was high in human cervical cancer cell lines. Interestingly, ICBP90 was up regulated by high risk type HPV16 E6 and E7, but not low-risk type HPV11. On the other hand, NIRF was down regulated by high risk type HPV16 E6 but not by E7. Low risk type HPV11 E6 did not affect the NIRF expression at all. We propose that ICBP90 overexpression, and reduced NIRF expression, found in cervical cancers, is an important event of a cervical carcinogenesis, and especially ICBP90 may offer a proliferating marker and therapeutic target for treating uterine cervical cancers.

Alterations of UHRF Family Expression and UHRF1/ICBP90 Inhibits Phosphatase and Tensin Homolog Expression in Endometrial Cancer.

INTRODUCTION: The altered protein expression of inverted CCAAT box-binding protein of 90 kDa/ubiquitin-like with PHD and RING finger domains 1 (ICBP90/UHRF1) and Np95-like ring finger protein (NIRF)/UHRF2, which belong to the ubiquitin-like with PHD and RING finger domains (UHRF) family, is linked to tumor malignancy and the progression of various cancers. To determine the role of NIRF and ICBP90 in endometrial tumorigenesis, we evaluated ICBP90 and NIRF expression levels in endometrial cancers. Also molecular alterations of phosphatase and tensin homolog (PTEN) expression are the important event for endometrial carcinogenesis; therefore, we investigated the involvement between ICBP90 and PTEN expression. METHODS: We used Western blot for NIRF, ICBP90, and PTEN expression, mutation analysis of NIRF gene, and immunohistochemical staining for the expression of NIRF and ICBP90. For immunohistochemical staining, we examined atypical endometrial hyperplasia, endometrial cancers, and noncancerous samples. RESULTS: Our data showed that the reduced expression of NIRF and overexpression of ICBP90 occurred in atypical endometrial hyperplasia and endometrial cancer compared to the normal endometrium. The decrease in NIRF expression was significantly correlated with histological grade. Expression of ICBP90 was high, especially in the peripheral margin of a cancer nest. Western blot analysis of endometrial cancer cell lines referred an opposite correlation between ICBP90 and PTEN expression. CONCLUSION: Our findings suggested that continually overexpressed ICBP90 may contribute to the inhibition of PTEN expression, which is a frequent and important event in endometrial carcinogenesis. We propose that the reduced NIRF expression and ICBP90 overexpression is an early event in endometrial carcinogenesis; thus ICBP90 may be useful as a therapeutic target in this disease.

Abnormal Expression of PICT-1 and Its Codon 389 Polymorphism Is a Risk Factor for Human Endometrial Cancer.

OBJECTIVE: The protein interacting with carboxyl terminus-1 (PICT-1) gene has been implicated as a tumor suppressor gene, and its alterations have been reported in several cancers. This study investigated the association of PICT-1 alterations with endometrial carcinogenesis. METHODS: We analyzed the entire coding region of the PICT-1 gene using polymerase chain reaction-single-strand conformation polymorphism and DNA sequencing to examine PICT-1 mutations in endometrial cancer. Western blotting and immunohistochemical staining were performed to analyze the protein expression and cellular localization of PICT-1 in endometrial cancer cell lines and patient samples. RESULTS: The codon 389 polymorphism of PICT-1 increased the risk of endometrial cancer. Interestingly, 2 of 13 endometrial cancers somatically acquired this mutation compared to normal counterparts. Immunohistochemical staining revealed lower levels of PICT-1 in samples from atypical endometrial hyperplasia and endometrial cancer tissues compared to normal endometrial tissues (p < 0.01). This decrease in PICT-1 expression was significantly correlated with histological grade and lymph node metastasis (p < 0.05). CONCLUSIONS: The findings of this study suggest that disruption of PICT-1 protein expression and codon 389 polymorphism can contribute to the pathogenesis or neoplastic progression of endometrial cancer.

The protein interacting with carboxyl terminus-1 codon 389 polymorphism impairs protein interacting with carboxyl terminus-1 function and is a risk factor for uterine cervical cancer.

PICT-1 is a nucleolar protein with various tumor suppressor functions. Recently, PICT-1 expression was reported to be dramatically reduced in several cancers. To investigate the role of PICT-1 in uterine cervical carcinogenesis, we examined its gene mutations, protein expression, cellular localization, and effect on p53 stabilization. PCR-SSCP analysis of the entire coding region of PICT-1 showed that a polymorphism at codon 389 may increase the risk of uterine cervical cancers, and also identified a novel missense mutation. Expression of wild-type PICT-1 inhibited the degradation of p53 in the presence or absence of HPV 18 E6 viral protein in vitro, while the expression of codon 389 polymorphic PICT-1 had a diminished inhibitory effect on p53 degradation. Moreover, we observed that PICT-1 degradation was induced both independently and cooperatively by E6 and E7 proteins from high-risk HPVs, but only marginal degradation was observed with proteins from low-risk HPV. Immunohistochemical staining of tumor samples revealed that lower levels of PICT-1 were observed in samples from CIN III and cervical cancer tissues, compared to normal cervical epithelium and CIN I, II tissues (P < 0.05). The reduction of PICT-1 may therefore be an early event in uterine cervical tumorigenesis. Our results indicated that PICT-1 counteracts HPV-induced p53 degradation and that aberrant PICT-1 function may contribute towards inactivating p53. Therefore, PICT-1 may play a critical role during the pathogenesis of uterine cervical cancers.

The human papillomavirus18 E7 protein inhibits CENP-C binding to α-satellite DNA.

Human papillomavirus (HPV) infection leads to aneuploidy, a numerical chromosomal aberration that is caused by dysregulation of chromosomal segregation. We previously found that the E7 proteins of high-risk HPVs, but not of low-risk HPVs, could bind to centromere protein-C (CENP-C). In this study, we first found that CENP-C could bind centromere α-satellite DNAs using ChIP analysis and HA-tagged CENP-C/nuc transfected 293T cells. We then investigated if HA-CENP-C/nuc binding to α-satellite DNAs was affected by the E7 proteins of high- or low-risk HPVs. We found that transfection of the FLAG tagged HPV18 E7 inhibited the binding of HA-CENP-C/nuc to α-satellite DNAs. This finding was confirmed in HeLa S3 cells transfected with siRNA targeted to HPV18 E7 expression. We therefore speculate that altered function of kinetochores as a result of inhibition of CENP-C and α-satellite DNAs binding may be associated with the chromosomal abnormalities observed in HPV18-positive cancers.

The PxDLLCxE sequence in conserved region 2 of human papilloma virus 18 protein E7 is required for E7 binding to centromere protein C.

High-risk human papillomaviruses (HPVs) are etiologically linked to human cervical and oral cancers. HPV infection leads to aneuploidy, a numerical chromosomal aberration caused by dysregulation of chromosomal segregation. We found that high-risk HPV18 and HPV58 E7 proteins bind to centromere protein C (CENP-C), a component of the kinetochore that is essential for proper chromosomal segregation. Low-risk HPV4, HPV6, and HPV11 E7s do not bind to CENP-C. The PxDLLCxE sequence in conserved region 2 (CR2) of HPV18 E7 is required for E7 binding to CENP-C. Our results indicate that differences in the ability of high- and low-risk HPV E7s to bind to CENP-C reflect the different oncogenic potentials of high- and low-risk type HPVs.