Joe Ensor

Targeting Mammalian Target of Rapamycin Synergistically Enhances Chemotherapy-Induced Cytotoxicity in Breast Cancer Cells

Purpose: The serine-threonine kinase mammalian target of rapamycin has emerged as a potential target for cancer therapy. Rapamycin and rapamycin analogs are undergoing clinical trials and have induced clinical responses in a subgroup of patients. Rapamycin has also been reported to enhance the efficacy of several cytotoxic agents. The aim of this study was to determine the nature of the interactions between rapamycin and chemotherapeutic agents used as first- and second-line agents against breast cancer. Experimental Design: We performed a multiple drug effect/combination index isobologram analysis in cells sensitive and resistant to rapamycin alone in vitro, and we evaluated the in vivo efficacy of combination therapy in a rapamycin-sensitive model. Results: In vitro, synergistic interactions were observed in combinations with paclitaxel, carboplatin, and vinorelbine. Additive effects were observed in combinations with doxorubicin and gemcitabine. Rapamycin dramatically enhanced paclitaxel- and carboplatin-induced apoptosis. This effect was sequence dependent and mediated at least partly through caspase activation. Furthermore, rapamycin enhanced chemosensitivity to paclitaxel and carboplatin in HER2/neu-overexpressing cells, suggesting a potential approach to these poorly behaving tumors. Cell lines that are resistant to the growth-inhibitory effect of rapamycin were also resistant to rapamycin-mediated chemosensitization. In vivo, rapamycin combined with paclitaxel resulted in a significant reduction in tumor volume compared with either agent alone in rapamycin-sensitive tumors. Conclusions: Rapamycin potentiates the cytotoxicity of selected chemotherapeutic agents in cell lines sensitive to the effects of rapamycin due to aberrations in the phosphatidylinositol 3′-kinase/Akt pathway, suggesting that combination therapy may be effective in patients selected for aberrations in this pathway.

MicroRNA-196a targets annexin A1: a microRNA-mediated mechanism of annexin A1 downregulation in cancers.

Suppression of annexin A1 (ANXA1), a mediator of apoptosis and inhibitor of cell proliferation, is well documented in various cancers but the underlying mechanism remains unknown. We investigated whether decreased ANXA1 expression was mediated by microRNAs (miRNAs), which are small, non-coding RNAs that negatively regulate gene expression. Using Sanger miRBase, we identified miR-584, miR-196a and miR-196b as potential miRNAs targeting ANXA1. Only miRNA-196a showed significant inverse correlation with ANXA1 mRNA levels in 12 cancer cell lines of esophageal, breast and endometrial origin (Pearsons correlation −0.66, P=0.019), identifying this as the candidate miRNA targeting ANXA1. Inverse correlation was also observed in 10 esophageal adenocarcinomas (Pearsons correlation −0.64, P=0.047). Analysis of paired normal/tumor tissues from additional 10 patients revealed an increase in miR-196a in the cancers (P=0.003), accompanied by a decrease in ANXA1 mRNA (P=0.004). Increasing miR-196a levels in cells by miR-196a mimics resulted in decreased ANXA1 mRNA and protein. In addition, miR-196a mimics inhibited luciferase expression in luciferase plasmid reporter that included predicted miR-196a recognition sequence from ANXA1 3′-untranslated region confirming that miR-196a directly targets ANXA1. miR-196a promoted cell proliferation, anchorage-independent growth and suppressed apoptosis, suggesting its oncogenic potential. This study demonstrated a novel mechanism of post-transcriptional regulation of ANXA1 expression and identified miR-196a as a marker of esophageal cancer.

Phase I/II Study of Trastuzumab in Combination With Everolimus (RAD001) in Patients With HER2-Overexpressing Metastatic Breast Cancer Who Progressed on Trastuzumab-Based Therapy

PURPOSE Trastuzumab resistance has been linked to activation of the phosphoinositol 3-kinase (PI3K) pathway. Phosphatase and tensin homolog (PTEN) is a dual phosphatase that counteracts the PI3K function; PTEN loss leads to activation of the Akt cascade and the downstream mammalian target of rapamycin (mTOR). Preclinical studies demonstrated that mTOR inhibition sensitized the response to trastuzumab in mice with HER2 overexpressing and PTEN-deficient breast xenografts. Our trial evaluated the safety and efficacy of the combination of everolimus and trastuzumab in women with HER2-overexpressing metastatic breast cancer (MBC) that progressed on trastuzumab-based therapy. PATIENTS AND METHODS This represents a pooled analysis (n = 47), stemming from two trials that occurred concurrently in The University of Texas MD Anderson Cancer Center, Beth Israel Deaconess Medical Center, and Dana-Farber Cancer Institute. Patients with HER2-overexpressing MBC who had progressed on trastuzumab-based therapy received trastuzumab every 3 weeks in combination with daily everolimus. RESULTS Among 47 patients, the combination of everolimus and trastuzumab provided partial responses in seven patients (15%) and persistent stable disease (lasting 6 months or longer) in nine patients (19%), resulting in a clinical benefit rate of 34%. The median progression-free survival (PFS) was 4.1 month. Fatigue, infection, and mucositis were the predominant nonhematologic toxicities. Trastuzumab did not have significant influence on the pharmacokinetic profile of everolimus. Patients with PTEN loss demonstrated decreased overall survival (P = .048). However, PFS was not affected by PTEN loss. CONCLUSION Inhibition of mTOR results in clinical benefit and disease response in patients with trastuzumab-resistant HER2-overexpressing MBC.

Association of MicroRNA Expression with Microsatellite Instability Status in Colorectal Adenocarcinoma

MicroRNAs (miRNA), small noncoding RNAs, are potential diagnostic and prognostic markers, as well as therapeutic targets. miRNA profiles of colorectal carcinomas have not been studied extensively in the context of microsatellite instability (MSI) status. We therefore evaluated 55 paired colorectal adenocarcinomas (CRC) and non-neoplastic mucosa samples using a panel of 24 miRNAs selected by literature review and prior studies in our laboratory. Stem-loop reverse transcriptase quantitative (real-time) polymerase chain reaction assays were done on RNA extracted from formalin-fixed, paraffin-embedded tissue of resection specimens. When miRNA expression was compared with clinicopathologic features and MSI status, eleven miRNAs (miR-183, -31, -20, -25, -92, -93, -17, -135a, -203, -133b, and -223) were over-expressed in CRC relative to mucosa, and nine (miR-192, -215, -26b, -143, -145, -191, -196a, -16, and let-7a) were under-expressed in CRC. Relative expression of miR-92, -223, -155, -196a, -31, and -26b were significantly different among MSI subgroups, and miR-31 and miR-223 were overexpressed in CRC of patients with hereditary non-polyposis colorectal cancer syndrome (Lynch syndrome). Our findings indicate that miRNA expression in CRC is associated with MSI subgroups, including low MSI and HNPCC-associated cancers, and that miRNAs may have posttranscriptional gene regulatory roles in these MSI subgroups and possible effects on the clinicopathologic and biomarker characteristics.

Association of Activated Transcription Factor Nuclear Factor κB With Chemoradiation Resistance and Poor Outcome in Esophageal Carcinoma

PURPOSE The lack of effective treatment for localized esosphageal cancer leads to poor patient outcome. Nuclear factor kappaB (NF-kappaB), a transcriptional factor, is constitutively activated or treatment induced in esophageal cancer and may influence treatment outcomes. PATIENTS AND METHODS Pre- and post-treatment cancer specimens from patients enrolled onto a clinical trial were studied for the expression of activated NF-kappaB protein and it was correlated with histologic features, pathologic response, metastatic potential, overall survival (OS), and disease-free survival (DFS). RESULTS Forty-three patients undergoing the same therapy on a protocol were studied. Twenty-one (72%) of 29 patients achieving less than complete pathologic response (pathCR) had NF-kappaB positive cancer, but only one (7%) of 14 patients achieving pathCR had NF-kappaB positive cancer (P = < .001). Activated NF-kappaB was significantly associated with aggressive pathologic features such as perineural, lymphatic, and/or vascular invasion (P = .0004). Eight (38%) of 21 NF-kappaB positive patients developed metastases compared to none of 22 NF-kappaB negative patients (P = .001). At a median follow-up of 23 months, 10 (48%) of 21 NF-kappaB positive patients had died compared to only one (5%) of 22 NF-kappaB negative patients (P = .0013). Observations were similar for DFS (P = .0006). In a multivariate model (using baseline stage, pathCR or less than pathCR, age, presence of metastatic lymph nodes in the surgical specimen, and NF-kappaB expression) NF-kappaB activation was the only independent predictor of DFS (P = .010) and OS (P = .015). CONCLUSION Our data suggest that esophageal cancers with activated NF-kappaB have aggressive clinical biology and poor treatment outcome. Additional understanding of NF-kappaB regulated pathways may uncover potential therapeutic targets.

14-3-3ζ Overexpression Defines High Risk for Breast Cancer Recurrence and Promotes Cancer Cell Survival

The ubiquitously expressed 14-3-3 proteins are involved in numerous important cellular functions. The loss of 14-3-3sigma is a common event in breast cancer; however, the role of other 14-3-3s in breast cancer is unclear. Recently, we found that 14-3-3zeta overexpression occurs in early stage breast diseases and contributes to transformation of human mammary epithelial cells. Here, we show that 14-3-3zeta overexpression also persisted in invasive ductal carcinoma and contributed to the further progression of breast cancer. To examine the clinical effect of 14-3-3zeta overexpression in advanced stage breast cancer, we performed immunohistochemical analysis of 14-3-3zeta expression in primary breast carcinomas. 14-3-3zeta overexpression occurred in 42% of breast tumors and was determined to be an independent prognostic factor for reduced disease-free survival. 14-3-3zeta overexpression combined with ErbB2 overexpression and positive lymph node status identified a subgroup of patients at high risk for developing distant metastasis. To investigate whether 14-3-3zeta overexpression causally promotes breast cancer progression, we overexpressed 14-3-3zeta by stable transfection or reduced 14-3-3zeta expression by siRNA in cancer cell lines. Increased 14-3-3zeta expression enhanced anchorage-independent growth and inhibited stress-induced apoptosis, whereas down-regulation of 14-3-3zeta reduced anchorage-independent growth and sensitized cells to stress-induced apoptosis via the mitochondrial apoptotic pathway. Transient blockade of 14-3-3zeta expression by siRNA in cancer cells effectively reduced the onset and growth of tumor xenografts in vivo. Therefore, 14-3-3zeta overexpression is a novel molecular marker for disease recurrence in breast cancer patients and may serve as an effective therapeutic target in patients whose tumors overexpress 14-3-3zeta.

Survival differences among women with de novo stage IV and relapsed breast cancer

BACKGROUND The objective of this retrospective study was to determine whether differences in survival exist between women with de novo stage IV and relapsed breast cancer. PATIENTS AND METHODS Three thousand five hundred and twenty-four women with de novo stage IV or relapsed breast cancer diagnosed from 1992 to 2007 were identified. Disease-free interval (DFI) was defined as the time from the diagnosis of primary nonmetastatic breast cancer to the date of the first distant metastases. Kaplan-Meier product limit method was used to estimate overall survival (OS). Cox proportional hazards model was fitted to determine the association between metastatic disease (relapsed versus de novo) and OS after controlling for other patient/tumor characteristics. RESULTS Six hundred and forty-three (18.2%) women had de novo stage IV disease and 2881 (81.8%) had relapsed disease. Median follow-up was 19 months. Median OS among patients with de novo stage IV and relapsed disease was 39.2 and 27.2 months, respectively (P < 0.0001). In the multivariable model, women with relapsed disease had an increased risk of death compared with patients with de novo disease (HR = 1.75, 95% confidence interval 1.47-2.08, P < 0.0001). When the multivariable model was stratified by DFI, women with relapsed disease with DFI <6 months, ≥6 months to <2 years, or ≥2 to <5 years each had a significantly higher risk of death compared with women with de novo stage IV disease. The risk of death was not statistically different among patients with relapsed disease with DFI >5 years compared with those with de novo disease. CONCLUSIONS This large cohort study provides further insight into the natural history of relapsed and de novo stage IV breast cancer. DFI plays an important role in the prognosis for patients with relapsed breast cancer.

Pretherapy nuclear factor-κB status, chemoradiation resistance, and metastatic progression in esophageal carcinoma

Background: Transcriptional factor nuclear factor-κB (NF-κB) seems to be associated with aggressive clinical biology (chemoradiation resistance and metastatic progression) of esophageal cancer. We hypothesized that activated NF-κB would define clinical biology irrespective of the type of chemotherapy or sequence administered. Methods: Pretherapy and/or posttherapy cancer specimens were examined for activated NF-κB and correlated with pathologic response to chemoradiation, metastatic potential, overall survival, disease-free survival, and type of chemotherapy or sequence used. Findings: Eighty patients undergoing chemotherapy and concurrent radiation were studied. Activated NF-κB prior to any therapy was associated with the lack of complete pathologic response (pathCR, P = 0.006). Forty-five (78%) of 58 patients achieving <pathCR had activated NF-κB in pretherapy and/or posttherapy cancer specimens versus 2 (9%) of 22 patients with pathCR (P = 0.001). Twenty-four (51%) of 47 patients with activated NF-κB in cancer developed metastases versus 7 (21%) of 22 patients with negative NF-κB in cancer (P = 0.01). At a median follow-up of 32 months, 25 (53%) of 47 patients with activated NF-κB cancer had died versus 3 (9%) of 33 patients with negative NF-κB cancer. NF-κB activation was the only independent predictor of disease-free survival (P = 0.01) and overall survival (P = 0.007) in a multivariate model. The class of chemotherapy or its sequence had no effect on NF-κB expression or patient outcome. Conclusions: Our data are the first to show that pretreatment-activated NF-κB significantly correlates with clinical biology of esophageal cancer, and most importantly, with pathCR. To therapeutically exploit NF-κB-regulated genes and their pathways, further research is warranted. [Mol Cancer Ther 2006;5(11):2844–50]

Hepatic artery chemoembolization for 110 gastrointestinal stromal tumors: response, survival, and prognostic factors.

The efficacy of hepatic artery chemoembolization (HACE) was evaluated for gastrointestinal stromal tumors (GISTs) metastatic to the liver.

14-3-3ζ Turns TGF-β's Function from Tumor Suppressor to Metastasis Promoter in Breast Cancer by Contextual Changes of Smad Partners from p53 to Gli2

Transforming growth factor β (TGF-β) functions as a tumor suppressor in premalignant cells but as a metastasis promoter in cancer cells. The dichotomous functions of TGF-β are proposed to be dictated by different partners of its downstream effector Smads. However, the mechanism for the contextual changes of Smad partners remained undefined. Here, we demonstrate that 14-3-3ζ destabilizes p53, a Smad partner in premalignant mammary epithelial cells, by downregulating 14-3-3σ, thus turning off TGF-βs tumor suppression function. Conversely, 14-3-3ζ stabilizes Gli2 in breast cancer cells, and Gli2 partners with Smads to activate PTHrP and promote TGF-β-induced bone metastasis. The 14-3-3ζ-driven contextual changes of Smad partners from p53 to Gli2 may serve as biomarkers and therapeutic targets of TGF-β-mediated cancer progression.