Yu-Zhen Feng

Up-regulation of small GTPases, RhoA and RhoC, is associated with tumor progression in ovarian carcinoma.

To clarify the role of small GTPases Rho in the biologic behavior of ovarian carcinoma, we first examined the mRNA expression of RhoA, RhoB, and RhoC in benign, borderline, and malignant ovarian tumors using RT-PCR and real-time RT-PCR. The expression and localization of RhoA protein were also analyzed by Western blotting and immunohistochemistry. Finally, we examined whether up-regulation of Rho enhances the invasiveness of ovarian cancer cells in vitro. Analysis of mRNA levels of the Rho family genes revealed that levels of both RhoA and RhoC were significantly higher in carcinomas than in benign tumors (RhoA, p = 0.0035; RhoC, p = 0.0006). According to histologic subtype, both RhoA and RhoC mRNA levels in serous carcinomas were significantly higher than those in other histologic types. With regard to the International Federation of Gynecological and Obstetrics stage classification, both of RhoA and RhoC mRNA levels were significantly higher in tumors of Stages III+IV than in those of Stages I+II (RhoA, p = 0.0200; RhoC, p = 0.0057). In addition, analysis of matched pairs of primary and disseminated lesions demonstrated that expression of both RhoA and RhoC mRNA was significantly higher in metastatic than in primary tumors. Examination of the protein level showed that expression of RhoA was also increased in advanced ovarian carcinomas, especially those of serous histology. Accordingly, we hypothesized that up-regulation of Rho GTPases plays an important role in the progression of ovarian carcinoma. Matrigel invasion assay using the ovarian cancer cell line, SKOV3, showed that up-regulation and activation after treatment with lysophosphatidic acid was associated with enhanced invasion of the cancer cells. This increase in invasiveness was suppressed by the addition of C3, a specific inhibitor of Rho. These findings suggest that up-regulation of Rho GTPases is important in the tumor progression of ovarian carcinoma and that Rho family proteins could be a molecular target in cancer therapy.

Overexpression of Hedgehog Signaling Molecules and Its Involvement in the Proliferation of Endometrial Carcinoma Cells

Purpose: Research has revealed abnormal activation of the hedgehog pathway in human malignancies. The present study was undertaken to examine the expression and functional involvement of the hedgehog pathway in endometrial tissues. Experimental Design: The expression of sonic hedgehog (Shh), patched (Ptch), Smoothened (Smo), and Gli1 was examined in various endometrial tissues and endometrial carcinoma cell lines. The effect of hedgehog signaling on the proliferation of endometrial carcinoma cell lines was also examined. Results: The expression of Shh, Ptch, Smo, and Gli1 was very weak in normal endometrium, but was increased in endometrial hyperplasia and carcinoma stepwisely with significant differences. There was no marked difference in the expression of these molecules in carcinomas according to stages and histologic grades. Treatment with cyclopamine, a specific inhibitor of the hedgehog pathway, for endometrial carcinoma Ishikawa and HHUA cells suppressed growth by 56% and 67%, respectively, compared with the control. The addition of recombinant Shh peptide to HHUA cells enhanced their proliferation by 41%. The silencing of Gli1 using small interfering RNA (siGli1) resulted in the growth suppression and down-regulation of Ptch expression. In addition, the cyclopamine/siGli1-induced growth suppression was associated with the down-regulation of cyclins D1 and A and N-myc. No somatic mutations for ptch and smo genes were detected in the endometrial carcinoma cases examined. Conclusions: The abnormal activation of this pathway is involved in the proliferation of endometrial carcinoma cells possibly in an auto-/paracrine fashion, suggesting the possibility of the hedgehog pathway being a novel candidate for molecular targeting.

BRAF Mutation in Endometrial Carcinoma and Hyperplasia: Correlation with KRAS and p53 Mutations and Mismatch Repair Protein Expression

Purpose: Although several gene abnormalities have been reported in endometrial carcinoma, the genetic alterations have not fully been elucidated. Recent studies have revealed frequent activating mutations of the gene for BRAF, an effector of Ras protein in the mitogen-activated protein kinase pathway, in several malignancies. However, the prevalence and significance of BRAF mutations in endometrial carcinoma remain unclear. Experimental Design: We examined BRAF mutations in exons 11 and 15 in 97 cases of endometrial carcinoma (endometrioid type, 78; nonendometrioid type, 19), 9 cases of atypical endometrial hyperplasia, and 20 cases of normal endometrium by direct sequencing. In addition, mutations of KRAS and p53 and the immunohistochemical expression of hMLH1 and hMSH2 were also examined. Results: Of the 97 carcinomas and 9 hyperplasias, 20 (21%) and 1 (11%) had BRAF mutations, most of them at previously unreported sites. Twenty samples of normal endometrium and 21 samples of normal endometrium obtained from sites adjacent to neoplastic lesions had no BRAF mutations. There was no apparent difference in the prevalence of BRAF mutation among stages, histologic subtypes, or grades. Mutations of KRAS and p53 were found in 18 (19%) and 22 (23%) cases, and 65 (67%) and 92 (95%) cases showed positive immunostaining for hMLH1 and hMSH2, respectively. BRAF mutation was more frequently found in hMLH1-negative cases (12 of 32, 41%) than in hMLH1-positive cases (7 of 65, 11%; P = 0.008), suggesting that it is associated with an abnormal mismatch repair function. Conclusions: These findings suggest that mutations of the BRAF gene are partly involved in the malignant transformation of the endometrium.

Expression of steroid receptor coactivators and corepressors in human endometrial hyperplasia and carcinoma with relevance to steroid receptors and Ki‐67 expression

To examine the steroid hormone dependent growth mechanism of human endometrial hyperplasia and carcinoma, expression levels of steroid receptor cofactors, such as coactivators (steroid receptor coactivator 1 [SRC‐1] and p300/cyclic AMP‐response element‐binding protein (p300/CBP]) and corepressors (nuclear receptor corepressor [NCoR] and silencing mediator for retinoid and thyroid‐hormone receptors [SMRT]), were investigated.

Expression of cyclins, p53, and Ki-67 in cervical squamous cell carcinomas: overexpression of cyclin A is a poor prognostic factor in stage Ib and II disease

We previously reported the overexpression of cyclins in uterine cervical carcinoma; however, their clinicopathological significance remained undetermined. In the present study, we examined the immunohistochemical expression of cyclins (D1, E, A, B1), p53 and Ki-67 in squamous cell carcinoma (stage Ib+II; 80 cases, stage III+IV; 23 cases). Correlations between the expression of cyclins and clinicopathological parameters and patient survival were statistically evaluated. The results indicated that in the normal squamous epithelium, the expression of cyclins and Ki-67 was sporadically observed in the parabasal layer. Of the 103 cervical carcinomas, overexpression of cyclins D1, E, A, B1 and p53 was observed in 13 (13%), 23 (22%), 25 (24%), 18 (18%) and 23 (22%) cases, respectively, with a slight predominance in advanced stage tumors. The expression of cyclin D1, E, A and p53 significantly correlated with that of Ki-67 (Spearman’s rank correlation). Univariate and multivariate analyses revealed that lymph node metastasis and cyclin A overexpression were independent prognostic factors for unfavorable outcomes in stage Ib+II patients. These findings suggest that the overexpression of various cyclins is involved in the acquisition of the vigorous growth potential of cervical carcinoma cells, and that cyclin A is an independent prognosticator of cervical carcinoma in early stages.

Intratumoral heterogeneous expression of p53 correlates with p53 mutation, Ki-67, and cyclin A expression in endometrioid-type endometrial adenocarcinomas.

To further elucidate the significance of p53 mutation in endometrial carcinoma, we investigated it in endometrioid-type endometrial carcinomas showing intratumoral heterogeneous p53 expression. In addition, we also examined the correlation of p53 mutation and cyclin A expression, because we previously reported a topological correlation between the expression of p53 and cyclin A. The p53 mutation in exons 5–8 in 54 cases of endometrial carcinoma showing immunohistochemical expression of p53 was examined using microdissected tissue DNAs. Of the 54 p53-positive endometrial carcinomas, 23 (43%) had p53 mutation with a tendency in histologically higher grade tumors. Ten of the 54 showed a heterogeneous p53 expression, and in 9 of the 10 cases, p53 mutation was present only in p53-positive sites, which were often found in histologically less differentiated areas with elevated Ki-67 in the same tumor. Cyclin A expression was topologically observed in p53-positive areas; however, it was noted in both tumors with (12/23, 52%) and without (18/31, 58%) p53 mutation. These results suggest that p53 mutation is a late event and plays an important role in the acquisition of malignant potentials in endometrioid-type endometrial adenocarcinomas. Unexpectedly, accumulation of the p53 protein itself may be important in cyclin A overexpression.