MicroRNAs (miRNA) are endogenous noncoding small RNAs that regulate the activity of mRNAs. Many miRNA genes, including let-7a-3, are located in CpG islands, suggesting possible epigenetic regulation of their expression. Promoter CpG island methylation of tumor suppressor genes is involved in cancer development and progression. Using real-time methylation-specific PCR and real-time reverse transcription-PCR, we analyzed DNA methylation in the let7a-3 gene and miRNA expression of let-7a in 214 patients with epithelial ovarian cancer to assess the effect of let-7a-3 methylation on the expressions of let-7a as well as a possible target of let-7 regulation, insulin-like growth factor-II (IGF-II). The association of let-7a-3 methylation with patient survival outcomes was also evaluated. let-7a-3 methylation was detected in epithelial ovarian cancer, and the expression of let-7a was slightly affected by the methylation, but the effect was not substantial. The methylation of let-7a-3, however, was inversely correlated with IGF-II expression and positively with insulin-like growth factor binding protein-3 (IGFBP-3) expression. Patients with methylated let-7a-3 seemed to have reduced risk for death compared with those without, and the association was independent of patient age at surgery, tumor grade, disease stage, and IGF-II or IGFBP-3 expression. No association was found for let7a-3 methylation and disease progression. These results suggest that the let-7a-3 gene is methylated and the methylation may affect IGF-II expression and the survival of ovarian cancer patients. Further investigation of the role of miRNAs and their regulation in cancer is warranted.

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Ovarian cancer patients with high ERCC1 expression or the C/C genotype at codon 118 may benefit from the combination of platinum and paclitaxel, while those with low ERCC1 expression or the C/T or T/T genotype may respond well to platinum without paclitaxel.

BACKGROUND.Methylation‐mediated suppression of detoxification, DNA repair, and tumor suppressor genes has been implicated in cancer development and progression. Studies also have indicated that concordant methylation of multiple genes (methylator phenotypes), rather than a single gene, may predict cancer prognosis. The current study was designed to determine whether a methylator phenotype exists in ovarian cancer, whether methylation frequencies differ between malignant ovarian tumors and ovarian tumors with low malignant potential (LMP or borderline), and whether methylation of multiple genes affects patient survival.METHODS.The current study included 234 consecutively diagnosed patients with either LMP (n = 19 patients) or malignant (n = 215 patients) ovarian tumors. DNA samples were extracted from fresh frozen tissues and were analyzed for methylation in the promoter region of 6 genes (p16, breast cancer 1 [BRCA1], insulin‐like growth factor‐binding protein 3 [IGFBP‐3], glutathione S‐transferase π 1 [GSTP1], estrogen receptor‐α [ER‐α], and human MutL homologue 1 [hMLH1]) by using methylation‐specific polymerase chain reaction analysis.RESULTS.The frequencies of methylation in malignant tumors and LMP tumors were 0% and 0% for GSTP1, respectively; 9% and 0% for hMLH1, respectively; 21% and 5% for BRCA1, respectively; 42% and 21% for p16, respectively; 44% and 26% for IGFBP‐3, respectively; and 57% and 42% for ER‐α, respectively. A methylator phenotype was not detected, but a calculated methylation index (MI) that was based on the total number of genes methylated in each tumor was associated with ovarian cancer risk and progression. A higher MI was associated with malignant tumors (odds ratio, 10.11; 95% confidence interval [95% CI], 1.19–85.75) and disease progression (hazards ratio, 6.53; 95% CI, 1.39–30.65).CONCLUSIONS.Although a methylator phenotype was not identified, the current results suggested that methylation of multiple genes may play an important role in ovarian cancer development and progression and may have clinical implications in prognosis. Cancer 2006. © 2006 American Cancer Society.

Human kallikrein 11 (hK11/trypsin-like serine protease/ TLSP, encoded by the KLK11 gene) is a member of the kallikrein family of secreted serine proteases. Recently, we developed a highly sensitive and specific immunoassay for hK11 and found that this protease is expressed in the prostate, stomach and trachea as well as in amniotic fluid and milk of lactating women. Elevated serum hK11 levels were found in 60% of men with prostate cancer and 70% of women with ovarian cancer. Also, hK11 expression was found to be under the regulation of steroid hormones, particularly estrogens, at the level of KLK11 transcription. We hypothesized that hK11 may be implicated in endocrine-related malignancies and serve as a novel prostate and ovarian cancer serological marker. The aim of our study was to examine if hK11 Similarly, in the subgroup of patients with grade 1-2 tumors, hK11-positivity was associated with higher OS in both univariate and multivariate analysis (HR of 0.23 and 0.17, p < 0.05). Finally, in women with optimal debulking after surgery (<1 cm residual tumor), hK11 positivity was associated with a slower disease progression. These results indicate that hK11 is a novel, independent marker of favorable prognosis in patients with ovarian cancer.

Insulin-like growth factor-I (IGF-I) is known to be involved in the development and progression of several types of solid tumors including ovarian cancer. IGF-I levels in local tissue is subject to both endocrine and paracrine/autocrine regulation. To investigate which regulation is more importantly involved in IGF-I action in ovarian cancer regarding tumor progression, we analyzed IGF-I mRNA expression (assuming only from paracrine/autocrine regulation) and peptide concentration (subject to both endocrine and paracrine/autocrine regulation) as well as a genetic polymorphism (CA dinucleotide repeats) in 215 epithelial ovarian cancer patients. Genomic DNA, total RNA and cytosol proteins were extracted from fresh tumor samples. Two alternatively spliced IGF-I transcripts (IGF-IA and IGF-IB) were analyzed using real-time PCR. Cytosol levels of free and total IGF-I were measured with enzyme-linked immunosorbent assay. DNA sizing analysis was performed to determine the CA polymorphism. The study showed that the CA polymorphism had a weak influence on IGF-I expression, but no effect on tumor progression. High levels of free, not total, IGF-I peptide were associated with elevated risk of disease progression (HR = 2.06; 95%CI: 1.22-3.50), and the association was independent of clinicopathologic features of the disease. One of the IGF-I transcripts (IGF-IA) had a similar but less significant impact on disease progression. Women with high IGF-I mRNA and peptide were at greater risk for disease progression compared to those with low in both (HR = 2.13; 95%CI: 1.13-3.95). These findings support the notion that IGF-I is involved in ovarian cancer progression and free IGF-I plays a more important role in the disease. The study also suggests that both endocrine and paracrine/autocrine are involved in the regulation of IGF-I activity in ovarian cancer.

Mounting evidence suggests that neuronal PAS domain protein 2 (NPAS2) and other circadian genes are involved in tumorigenesis and tumor growth, possibly through their control of cancer-related biologic pathways. A missense polymorphism in NPAS2 (Ala394Thr) has been shown to be associated with risk of human tumors including breast cancer. The current study further examined the prognostic significance of NPAS2 in breast cancer by genotyping the Ala394Thr polymorphism and measuring NPAS2 expression. DNA extracted from 348 breast cancer tissue samples was analyzed for NPAS2 genotype using the TaqMan allelic discrimination assay. Of these, 287 also had total RNA available for use in real-time PCR assays to determine NPAS2 expression. NPAS2 genotypes and expression levels were analyzed for associations with prognostic outcomes, as well as correlations with clinical characteristics. A high level of NPAS2 expression was strongly associated with improved disease free survival (AHR = 0.43, 95% CI: 0.21–0.86, P trend = 0.022) and overall survival (AHR = 0.42, 95% CI: 0.19–0.96, P trend = 0.036). In addition, there was a borderline, but nonsignificant association between the NPAS2 genotype corresponding to Thr394Thr and disease free survival (AHR = 1.82, 95% CI: 0.96–3.46). The Ala/Ala, Ala/Thr, and Thr/Thr genotypes were also differentially distributed by tumor severity, as measured by TNM classification (χ2 (6df, N = 344) = 14.96, P = 0.020). These findings provide the first evidence suggesting prognostic significance of the circadian gene NPAS2 in breast cancer.

Purpose: The insulin-like growth factor (IGF) system plays important roles in cancer; blocking IGF signaling has been shown to have therapeutic effects on tumor growth. Many studies have focused on the effect of IGF-I, but few have addressed IGF-II.To assess the role of IGF-II in cancer, we analyzed IGF-II expression in ovarian cancer and examined its association with disease characteristics and prognosis. Experimental Design: Included in the study were 215 patients with primary epithelial ovarian cancer. Fresh tumor specimens were collected during surgery, and the patients were followed for a median of 31 months. Total RNA was extracted from the tumor and analyzed for IGF-II, IGF binding protein 3 (IGFBP-3), and estrogen receptor-a expressions using quantitative reverse transcription PCR. Survival analysis was done to examine the associations of IGF-II with disease progression. Results: IGF-II expression was found to be higher in tumors with poor prognosis; this included tumors with advanced stage, poor differentiation, serous histology, and large residual lesions. Patients with high IGF-II had elevated risk for disease progression and death, although the significance became less evident when the analysis was adjusted for clinical and pathologic variables. IGFBP-3 expression was higher in less aggressive tumors, but was not associated with disease progression. The expression of estrogen receptor-a had no effect on survival. Conclusion:This study found evidence that IGF-II expression is associated with disease progression, suggesting that IGF-II and IGF signaling are potential targets for ovarian cancer treatment. The study also indicates that IGF-II and IGFBP-3 have limited value in prognosis because of their strong associations with disease stage and tumor grade.