Weiguo Wu

Her-2/neu Overexpression and Amplification in Uterine Papillary Serous Carcinoma

PURPOSE Uterine papillary serous carcinoma (UPSC) is an aggressive subtype of endometrial cancer characterized by early metastasis, resistance to therapy, and a high mortality rate. Little is known about the biology of these tumors. Smaller studies suggest that Her-2/neu may be involved in the tumorigenesis of this disease. The purpose of this study was to evaluate the protein expression and gene amplification of Her-2/neu in UPSC and to determine its prognostic value. PATIENTS AND METHODS Tumor tissue from 68 patients with UPSC treated at The University of Texas M.D. Anderson Cancer Center from 1989 to 2002 was available. Her-2/neu expression was evaluated by immunohistochemistry (IHC). Overexpression was defined as complete membrane staining in greater than 10% of the cells. In tumors with overexpression of Her-2/neu by IHC, fluorescence in situ hybridization (FISH) was performed to assess gene amplification. Clinical and pathologic information was obtained from medical records. RESULTS Twelve (18%) of 68 tumors demonstrated Her-2/neu overexpression. Of these, only two showed gene amplification. When evaluating all 68 patients, Her-2/neu overexpression was associated with a poorer overall survival (OS; P = .008). In our multivariate Cox proportional hazards models, Her-2/neu IHC overexpression, lymph node status, and stage were each associated with OS (P < or = .05). CONCLUSION Positive IHC overexpression of Her-2/neu was seen in 18% of UPSCs but was rarely correlated with Her-2/neu gene amplification. Overexpression of Her-2/neu was associated with a worse overall prognosis. The use of trastuzumab (Herceptin; Genentech, South San Francisco, CA) in women with UPSC should be further evaluated in a clinical trial setting.

Loss of Tuberous Sclerosis Complex-2 Function and Activation of Mammalian Target of Rapamycin Signaling in Endometrial Carcinoma

Purpose: The involvement of phosphatase and tensin homologue deleted on chromosome ten (PTEN) in endometrial carcinoma has implicated phosphatidylinositol 3-kinase signaling and mammalian target of rapamycin (mTOR) activation in this disease. Understanding the extent of mTOR involvement and the mechanism responsible for activation is important, as mTOR inhibitors are currently being evaluated in clinical trials for endometrial carcinoma. Although tuberous sclerosis complex 2 (TSC2) is the “gatekeeper” for mTOR activation, little is known about defects in the TSC2 tumor suppressor or signaling pathways that regulate TSC2, such as LKB1/AMP-activated protein kinase, in the development of endometrial carcinoma. Experimental Design: We determined the frequency of mTOR activation in endometrial carcinoma (primary tumors and cell lines) and investigated PTEN, LKB1, and TSC2 defects as underlying cause(s) of mTOR activation, and determined the ability of rapamycin to reverse these signaling defects in endometrial carcinoma cells. Results: Activation of mTOR was a consistent feature in endometrial carcinomas and cell lines. In addition to PTEN, loss of TSC2 and LKB1 expression occurred in a significant fraction of primary tumors (13% and 21%, respectively). In tumors that retained TSC2 expression, phosphorylation of tuberin at S939 was observed with a high frequency, indicating that mTOR repression by TSC2 had been relieved via AKT phosphorylation of this tumor suppressor. In PTEN-null and LKB1-null endometrial carcinoma cell lines with functional inactivation of TSC2, phosphatidylinositol 3-kinase (PI3K) inhibitors wortmannin and LY294002 were able to inhibit AKT and mTOR signaling and reverse TSC2 phosphorylation. In contrast, although rapamycin inhibited mTOR signaling, it did not relieve phosphorylation of TSC2 at S939. Conclusions: Inactivation of TSC2 via loss of expression or phosphorylation occurred frequently in endometrial carcinoma to activate mTOR signaling. High-frequency mTOR activation supports mTOR as a rational therapeutic target for endometrial carcinoma. However, whereas rapamycin and its analogues may be efficacious at inhibiting mTOR activity, these drugs do not reverse the functional inactivation of TSC2 that occurs in these tumors.

Primary chemoprevention of endometrial hyperplasia with the peroxisome proliferator-activated receptor gamma agonist rosiglitazone in the PTEN heterozygote murine model.

PTEN mutations have been implicated in the development of endometrial hyperplasia and subsequent cancer. Peroxisome proliferator-activated receptor gamma (PPAR-γ) agonists have demonstrated antineoplastic and chemopreventive effects. The purpose of this study was to evaluate the effects of the PPAR-γ agonist rosiglitazone on both PTEN wild type and PTEN null cell lines and in the PTEN heterozygote(+/−) murine model. Hec-1-A (PTEN wild type) and Ishikawa (PTEN null) cells were treated with rosiglitazone. Thirty-five female PTEN+/− mice were genotyped and placed into one of four groups for treatment for 18 weeks: A) PTEN wild type with 4 mg/kg rosiglitazone, B) PTEN+/− mice with vehicle, C) PTEN+/− mice with 4 mg/kg rosiglitazone, and D) PTEN+/− mice with 8 mg/kg rosiglitazone. Proliferation and apoptosis were measured by bromodeoxyuridine (BrdU) and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling of DNA fragmentation sites assay. Rosiglitazone caused cell growth inhibition in both Hec-1-A and Ishikawa in a dose-dependent manner (P< 0.02 and P< 0.03, respectively). Rosiglitazone also induced apoptosis in both Hec-1-A (P< .001) and Ishikawa (P< .001) cells in a dose-dependent manner. In the murine model, rosiglitazone decreased proliferation of the endometrial hyperplastic lesions (B vs C; 39.7% vs 9.3% and B vs D; 39.7% vs 4.2%; P< 0.0001) and increased apoptosis of glandular endometrial epithelial cells (B vs C; 2.8% vs 22.4%; P< 0.0001 and B vs D; 2.8% vs 30.2%; P= 0.003). PPAR-γ agonist rosiglitazone inhibits proliferation and induces apoptosis in both PTEN intact and PTEN null cancer cell lines and in hyperplastic endometrial lesions in the PTEN+/− murine model.