The Significance of Mismatch Repair Deficiency in Young Patients With Endometrial Cancer.

The objective of this study was to identify the tumor characteristics associated with mismatch repair deficiency in young patients with endometrial carcinoma. Young patients (45 yr old or younger) with endometrial carcinoma treated by hysterectomy in our institution between July 2001 and June 2009 were identified. The clinical and pathologic data were obtained by review of clinical records. Among the 122 cases identified, paraffin sections were available in 67 cases for immunohistochemical staining and frozen tissue available in 62 cases for microsatellite instability (MSI) analysis. Both paraffin sections and frozen tissue were available in 36 cases. Among the 67 cases with immunohistochemical staining, 22 (32.8%) showed loss of expression of at least 1 mismatch repair protein. Defective MLH1 or MSH2 expression was associated with poor prognostic factors, including a higher incidence of pelvic lymph nodes metastasis (P=0.018) and higher stage (P=0.022) for MLH1, and an increased risk of lymphovascular permeation (P=0.015) for MSH2. On the contrary, defective MSH6 protein expression was associated with a lower incidence of high-grade tumors (P=0.04). Among the 62 cases with MSI analysis, 12 (19.4%) tumors were classified as microsatellite-high (MSI-H), whereas 2 (3.2%) were classified as microsatellite-low (MSI-L). There was no difference in the pathologic characteristics between MSI-stable and MSI-H tumor. We concluded that defective mismatch repair expression is important in young patients with endometrial carcinoma, with MSH6 protein being most commonly affected. The phenotype resulting from defective MSH6 expression was different from that caused by MLH1 or MSH2 loss.

Targeting estrogen receptor subtypes (ERα and ERß) with selective ER modulators in ovarian cancer.

Ovarian cancer cells express both estrogen receptor α (ERα) and ERß, and hormonal therapy is an attractive treatment option because of its relatively few side effects. However, estrogen was previously shown to have opposite effects in tumors expressing ERα compared with ERß, indicating that the two receptor subtypes may have opposing effects. This may explain the modest response to nonselective estrogen inhibition in clinical practice. In this study, we aimed to investigate the effect of selectively targeting each ER subtype on ovarian cancer growth. Ovarian cancer cell lines SKOV3 and OV2008, expressing both ER subtypes, were treated with highly selective ER modulators. Sodium 3'-(1-(phenylaminocarbonyl)-3,4-tetrazolium)-bis(4-methoxy-6-nitro) benzene sulfonic acid hydrate (XTT) assay revealed that treatment with 1,3-bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole dihydrochloride (MPP) (ERα antagonist) or 2,3-bis(4-hydroxy-phenyl)-propionitrile (DPN) (ERß agonist) significantly suppressed cell growth in both cell lines. In contrast, 4,4',4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl) trisphenol (PPT) (ERα agonist) or 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a]-pyrimidin-3-yl]phenol (PHTPP) (ERß antagonist) significantly enhanced cell growth. These results were confirmed on a xenograft model where SKOV3 cells were injected s.c. into ovariectomized mice. We observed that the average size of xenografts in both the DPN-treated group and the MPP-treated group was significantly smaller than that for the vehicle-treated group. In addition, we found that phospho-AKT expressions in SKOV3 cells were reduced by 80% after treatment with MPP and DPN, indicating that the AKT pathway was involved. The combined treatment with MPP and DPN had a synergistic effect in suppressing ovarian cancer cell growth. Our findings indicate that targeting ER subtypes may enhance the response to hormonal treatment in women with ovarian cancer.

TAp73-mediated the activation of c-Jun N-terminal kinase enhances cellular chemosensitivity to cisplatin in ovarian cancer cells.

P73, one member of the tumor suppressor p53 family, shares highly structural and functional similarity to p53. Like p53, the transcriptionally active TAp73 can mediate cellular response to chemotherapeutic agents in human cancer cells by up-regulating the expressions of its pro-apoptotic target genes such as PUMA, Bax, NOXA. Here, we demonstrated a novel molecular mechanism for TAp73-mediated apoptosis in response to cisplatin in ovarian cancer cells, and that was irrespective of p53 status. We found that TAp73 acted as an activator of the c-Jun N-terminal kinase (JNK) signaling pathway by up-regulating the expression of its target growth arrest and DNA-damage-inducible protein GADD45 alpha (GADD45α) and subsequently activating mitogen-activated protein kinase kinase-4 (MKK4). Inhibition of JNK activity by a specific inhibitor or small interfering RNA (siRNA) significantly abrogated TAp73-mediated apoptosis induced by cisplatin. Furthermore, inhibition of GADD45α by siRNA inactivated MKK4/JNK activities and also blocked TAp73-mediated apoptosis induction by cisplatin. Our study has demonstrated that TAp73 activated the JNK apoptotic signaling pathway in response to cisplatin in ovarian cancer cells.

Prevalence and risk factors of Human Papillomavirus (HPV) infection in southern Chinese women - a population-based study.

BACKGROUND: Persistent high-risk type Human papillomavirus (HPV) infection is recognized as a necessary cause of cervical cancer. This study aimed to compare the HPV prevalence and risk factors between women residing in Hong Kong (HK) and Guangzhou (GZ) region of China. METHODOLOGY/PRINCIPAL FINDINGS: A total of 1,570 and 1,369 women were recruited from HK and GZ, respectively. The cytology samples were collected and tested for HPV infection. The overall and type-specific HPV prevalence and the potential risk factors for acquisition of HPV infection were studied. Women with normal cytology in the GZ cohort had significantly higher HPV prevalence (10%) than those in the HK cohort (6.2%, p<0.001). The patterns of the age-specific HPV prevalence were also different between the two cohorts. In the HK cohort, women at the age of 20-29 years old had the highest prevalence and a second peak was observed in the age of ≥ 60 years old. In the GZ cohort, the highest HPV prevalence was also observed in 20-29 years old but declined as the age increased and a second peak was not seen. HPV16 and HPV52 were the most common high-risk types found in the HK and GZ cohorts, respectively. Age was the most consistently observed independent risk factor for HPV infection in the HK, while the number of sexual partners had association in the GZ cohort. CONCLUSIONS/SIGNIFICANCE: Our study provides the current status and the epidemiological characteristics of HPV prevalence in Southern Chinese women. The results strongly suggested that population education and the effective cervical cancer screening would be vital in the prevention of cervical cancer.

Promoter methylation of death-associated protein kinase and its role in irradiation response in cervical cancer.

This study was aimed at investigating the death-associated protein kinase (DAPK) promoter methylation and its clinical relevance in cervical cancer. The DAPK promoter methylation was detected by methylation-specific PCR (MSP) and correlated with DAPK mRNA and protein expression. The effect of DAPK expression on the radiosensitivity of the cervical cancer cell line was assessed by overexpressing DAPK in the radioresistant cell line SiHa. DAPK hypermethylation was found in 56.08% of the cervical cancer samples and was associated with the tumor histological cell type of squamous cell carcinoma (p=0.002) and advanced tumor stage (p=0.005). Subsequently, DAPK protein expression was found to significantly decrease in cervical cancer samples when compared to normal tissues. The DAPK mRNA and protein expression levels were absent or remarkably reduced in SiHa and HeLa in which the DAPK promoter was hypermethylated. The expression levels of DAPK could be restored after demethylation treatment with 5-aza-2'-deoxycytidine. Overexpressing DAPK in vitro had no significant influence to the survival of the radioresistant SiHa cell after being challenged by irradiation. Our findings suggest that DAPK might not directly be responsible for the cellular radiosensitivity, however, DAPK hypermethylation appeared to be of prognostic significance in the advanced stages of cervical cancer.

Expression of deltaNp73 and TAp73alpha independently associated with radiosensitivities and prognoses in cervical squamous cell carcinoma.

PURPOSE: The p73 gene produces different protein isoforms using alternative promoters and splicing, which have different biological characteristics. This study was to investigate the expression patterns of two distinct p73 isoforms (deltaNp73 and TAp73alpha) in cervical squamous cell carcinomas (SCC) and the relationship between their expressions and prognostic significance in cervical SCC patients. EXPERIMENTAL DESIGN: We investigated the protein expressions of deltaNp73 and TAp73alpha in 117 cervical SCC and 113 normal cervical tissues using immunohistochemistry. The expression levels were analyzed with clinical variables and patients' survival. RESULTS: DeltaNp73and TAp73alpha were significantly overexpressed in cervical SCC compared with those in normal cervical epithelium (P < 0.001). However, their expressions were inversely correlated (P < 0.001, R = -0.368) and associated with differential tumor radiosensitivity. Overexpression of deltaNp73 was significantly found in SCC resistant to irradiation (P < 0.001), whereas increase of TAp73alpha expression was observed in the majority of SCC sensitive to irradiation (P < 0.001). Multivariate and survival analyses indicated that the expressions of deltaNp73 and TAp73alpha were independently associated with prognosis: deltaNp73 was associated with recurrence of the disease [P = 0.001; odds ratio (OR), 4.857] and an adverse outcome (P = 0.012; OR, 4.676), whereas TAp73alpha predicted a better survival of cervical SCC patients (P = 0.018; OR, 0.065). CONCLUSIONS: The p73 gene might be an important determinant of cellular response to irradiation. The expressions of the two main isoforms (deltaNp73 and TAp73alpha) might be potential markers for predicting the prognosis and sensitivity to radiotherapy in patients with cervical SCC.

Enhancement of the radiosensitivity of cervical cancer cells by overexpressing p73alpha.

Radiation therapy is the most effective therapy for cervical cancer in advanced stages. p53 plays a critical role in the cellular response to radiation-induced DNA damage. However, p53 function is often impaired in the presence of the oncoprotein E6 from human papillomavirus, which is often associated with the development of cervical cancer. p73, a p53 family member, is highly similar to p53, but is resistant to the degradation by human papillomavirus E6. In this study, we investigated the role of p73alpha in relation to cellular radiosensitivity in the p53-impaired cervical cancer cells. Radiosensitivity and irradiation-induced apoptotic cell death were examined in the exogenous overexpressed p73alpha- and p53-impaired cells. Our results showed that the endogenous p73alpha expressed only in the radiosensitive cervical cancer C4-1 cells, but not in the radioresistant SiHa, Caski, and HeLa cells. Overexpression of exogenous p73alpha by transfection in the radioresistant cells resulted in a significant increase of cellular sensitivity to radiation. Enhanced radiosensitivity in p73alpha-transfected cells was attributed by increase of cellular apoptosis. Coactivation of p21 was also observed in the p73alpha-transfected cells upon radiation treatment. In summary, our findings suggested that p73alpha is an important determinant of cellular radiosensitivity in the p53-impaired cervical cancer cells.

p73 expression is associated with the cellular radiosensitivity in cervical cancer after radiotherapy.

Apoptosis is one of the causes of cell death in cervical cancer following radiotherapy. By studying the gene expression profile with cDNA apoptotic array, the p73 gene was found overexpressed in radiosensitive cervical cancers when compared with radioresistant ones. To investigate the role of the p73 gene in relation to clinical assessment of radiosensitivity in cervical cancer based on the findings of residual tumor cells in cervical biopsies after completion of radiotherapy, we studied the protein expression of p73 in 59 cervical cancers after radiotherapy and 68 normal cervices using immunohistochemistry. The expression of p73 was found to be significantly increased in cancer samples and, more importantly, in those samples sensitive to radiotherapy (P < 0.001). The overexpression of p73 actually predicted a better prognosis in cervical cancer patients (P < 0.001). To investigate the possible involvement of p73 downstream genes, the protein expressions of p21 and Bax were studied. The expression of p21, but not Bax, was found to be positively correlated with the expression of p73 (P = 0.001). Furthermore, the epigenetic regulation of p73 expression via DNA methylation was also investigated in 103 cervical cancers and 124 normals. Hypermethylation of p73 gene was observed in 38.8% of cervical cancers, and it was significantly associated with reduced or absent p73 expression (P < 0.001). Reactivation of p73 expression in two cervical cancer cell lines by demethylation treatment supported the role of methylation in the regulation of p73 expression. Our findings suggested that p73 expression was related to the radiosensitivity of cervical cancer cells and may play an important role in the regulation of cellular radiosensitivity.

Differential gene expression in cervical cancer cell lines before and after ionizing radiation.

Our previous study demonstrated a correlation between increased apoptotic index in pre-radiotherapy cervical cancer and poor patient survival. Apoptosis may thus play an important role in the response of cervical cancer to radiation. Most of cervical carcinomas are associated with human papillomavirus (HPV), and the oncoproteins E6 and E7 disrupt the functions of tumour suppressor genes, resulting in genetic alteration. To understand the multiple genetic changes related to cell radiosensitivity and the induction of apoptosis, two cervical cancer cell lines, SiHa (with HPV infection) and C-33A (contains a mutant p53 gene), were selected for present studied. The gene expression patterns in these cell lines were compared before and after radiation. When compared to normal cervical tissues, differential expressions were observed in 46 genes among the two cell lines studied. Thirty-three genes showed altered expressions after radiation induction. Three out of ten genes that showed differential responsiveness to radiation in the two cell lines were further confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR). Bak and c-abl were found to be potential genes that may play important roles in signaling apoptosis in cervical cancer cells following radiation induction.