Met Is the Most Frequently Amplified Gene in Endometriosis-Associated Ovarian Clear Cell Adenocarcinoma and Correlates with Worsened Prognosis

Abstract

Clear cell adenocarcinoma of the ovary (OCC) is a chemo-resistant tumor with a relatively poor prognosis and is frequently associated with endometriosis. Although it is assumed that oxidative stress plays some role in the malignant transformation of this tumor, the characteristic molecular events leading to carcinogenesis remain unknown. In this study, an array-based comparative genomic hybridization (CGH) analysis revealed Met gene amplification in 4/13 OCC primary tumors and 2/8 OCC cell lines. Amplification of the AKT2 gene, which is a downstream component of the Met/PI3K signaling pathway, was also observed in 5/21 samples by array-based CGH analysis. In one patient, both the Met and AKT2 genes were amplified. These findings were confirmed using fluorescence in situ hybridization, real-time quantitative PCR, immunoblotting, and immunohistochemistry. In total, 73 OCC cases were evaluated using real-time quantitative PCR; 37.0% demonstrated Met gene amplification (>4 copies), and 8.2% had AKT2 amplification. Furthermore, stage 1 and 2 patients with Met gene amplification had significantly worse survival than patients without Met gene amplification (p<0.05). Met knockdown by shRNA resulted in reduced viability of OCC cells with Met amplification due to increased apoptosis and cellular senescence, suggesting that the Met signaling pathway plays an important role in OCC carcinogenesis. Thus, we believe that targeted inhibition of the Met pathway may be a promising treatment for OCC.

The PI3K/AKT/mTOR pathway as a therapeutic target in ovarian cancer

“…PIK3CA mutation with gain of function has been suggested to occur in 33-40% of OCCC and 12-20% of EnOC [18]. Furthermore, in a previous study AKT2 amplification was observed in 14% of OCCC cases [19]. In addition to these genetic alterations, the loss of PTEN expression has been detected in 40% of OCCC [20].…”

Lack of presence of the human cytomegalovirus in human glioblastoma

“…Our FISH analysis is highly sensitive because we probed BAC DNA containing full-length HCMV genome, and in our previous study, we could readily detect two copies of the human genome in a cell using the same method. 24 Earlier studies reporting positive signals of HCMV DNA and RNA in the glioblastoma cells by in situ hybridization utilized antibody-mediated enhancement of the primary signals, 1,2 which may have resulted in augmentation of nonspecific bindings of the probes, leading to misinterpretation of the signals. Furthermore, our LC/MS/MS analysis revealed that proteins extracted from the positive bands detected in immunoblotting using IE1 and pp28 antibodies were non-viral human proteins such as HSA and MBP, suggesting previously unknown cross-reactivity of these antibodies and also the unreliability of not only positive immunoblot bands but also immunohistochemical staining.…”

“…23 Fluorescence In Situ Hybridization HCMV BAC DNA was labeled with SpectrumOrange using a Nick Translation Kit (Abbott Molecular, Abbott Park, IL, USA) according to the manufacturer's recommendation and FISH analysis for HCMV genome detection was performed as described previously. 24 …”

Napsin A is a specific marker for ovarian clear cell adenocarcinoma

“…20,21 Compared with serous adenocarcinoma, clear cell adenocarcinoma is resistant to standard platinum-based chemotherapy; 22 thus, survival rates in patients with advanced stages of ovarian clear cell adenocarcinoma are poor. Therefore, it is important to distinguish clear cell adenocarcinoma from other histological subtypes in ovarian cancer.…”