Citations

Abstract Heregulin internalization to the nucleus is mediated via binding to Nucleolin Lin Yang, and Ruth Lupu. Department of Laboratory Medicine and Pathology, Mayo Clinic Foundation, Rochester, Minnesota 55902 Heregulin (HRG) is known as a soluble secreted growth factor of EGF-like family, which binds and activates HER3 and HER4 and transactivates HER2 and HER1 receptors. It has been shown that HRG translocates to the nucleus in triple negative breast cancer cells that express high level of HRG. The mechanism by which HRG translocates to the nucleus is still unknown. We have recently uncovered that Nucleolin binds to Heregulin and allows HRG to translocate to the nucleus. Mass spectrometry analysis revealed that multifunctional protein Nucleolin is a major HRG-associated protein. Using co-immunoprecipitation we confirmed HRG interacts with Nucleolin in both endogenous and ectopic levels. Then, we made deleted mutants of HRG to map the Nucleolin binding domain on HRG and we found that Nucleolin binds to HRG on its N-terminus which contains a putative nuclear localization signal (NLS). Remarkably, in these cells we found a striking peri-nuclear accumulation when Nucleolin was knocked down. These results show for the first time that HRG translocate to the nucleus mediated by Nucleolin binding in breast cancer cells. Importantly, the nuclear function of HRG remains as a positive regulator of chemosensitization. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 271.

Abstract In pancreatic cancer both chemotherapy and radiotherapy have shown deficient results in treating the disease, indicating a fundamental need for more efficient therapies. Most pancreatic cancer patients present with an advanced form of the disease that is incurable by surgery, and will receive palliative treatment in the form of surgery, chemotherapy, radiotherapy and symptom control. There are few standard chemotherapeutics for the treatment of pancreatic cancer, although Gemcitabine and 5-Fluorouracil (5-FU) are the most widely used. In search for specific nutritional, and/or pharmacological agents to target pancreatic cancer cells/tissues we identified a series of nutritional supplements known as polyunsaturated fatty acids (PUFAs) that have an inhibitory effect on cancer cells. However, Gamma-Linolenic-Acid (GLA), a member of the ω-6 family of PUFAs exerts selective cytotoxic effects on pancreatic cancer cells without affecting normal epithelial cells. The goal of our study was to determine whether GLA could sensitize the targeted pancreatic cancer cells to chemotherapeutic agents (Gemcitabine or 5-FU). Therefore, pancreatic cancer cells were treated initially with GLA followed by each of the chemotherapeutic agents separately: Our results demonstrated that: 1) GLA induced growth inhibition and apoptosis of pancreatic cancer cells (Panc-1 and BxPC3); 2) the combination of GLA and Gemcitabine or GLA and 5-FU: a) promote a synergistic inhibitory effect on the growth of pancreatic cancer cells; b) inhibition of anchorage-independent growth; and 4) inhibition of morphogenesis in 3-D matrigel culture. These results show that GLA increases the sensitivity of pancreatic cancer cells to chemotherapy through a synergistic effect with Gemcitabine or 5-FU, implying that GLA could be used as a supportive drug for the pancreatic cancer patients receiving the current chemotherapeutic regimens. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 209.

Abstract Numerous solid tumors confirm increased expression of FASN. FASN expression is upregulated in early steps of breast cancer, such as DCIS, and is associated with poor clinical outcome in more advanced disease. The objective of this study is to evaluate FASN inhibition as a prevention of breast cancer progression and as an effective treatment of metastasis. We utilized the model the MCF10CA1 series of cell lines, which complete the spectrum of breast cancer progression ranging from non-transformed breast epithelial cells to metastatic breast cancer cells. These metastatic cell lines are CA1A and CA1D cells (short for MCF10A-CA1A and MCF10A-CA1D), which metastasize to the lung following a tail vein injection. Interestingly, we determine that with the progression of breast cancer in these model series the level of FASN was correlated with the evolution to a more aggressive phenotype. The CA1A and CA1D cells expressed the highest levels of FASN. To determine whether FASN plays a role in the aggressiveness of these cells we introduced a specific FASN silencing RNA into CA1A and CA1D cells and isolated stable cell lines in which FASN expression was significantly reduced. Stable expression of a FASN shRNA completely abrogated the anchorage-independent growth ability of the metastatic cells and furthermore these cells reverted from EMT to MET (Mesenchymal Epithelial Transition) as demonstrated by a Matrigel 3Dimentional (3D) assay and the immunofluorescence staining of E-Cadherin in matrigel. These results emphasize the potential of FASN as a therapeutic target and as a key modulator of breast cancer progression and metastasis. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6160.

Abstract Estrogen receptors (ERs) play key roles in breast cancer development and influence treatment outcome in breast cancer patients. More than 60% of human breast cancer tumors express ER and many of those are Estrogen (E2) dependent. ER positive tumors are considered to have a good prognosis; however some tumors escape to E2 requirements. Thus, the identification of molecules that regulate ER function may facilitate development of breast cancer treatment strategies. The pro-angiogenic factor CYR61 induces breast cancer cells to bypass the normal estrogen requirements for growth and acquire an estrogen-independent and antiestrogen resistant phenotype. However, the mechanism by which CYR61 regulates the hormonal response in breast cancer is not well understood. We over-expressed CYR61 in the ER positive cells MCF-7 (MCF-7/CYR61). Our results demonstrated that CYR61 induces constitutive transcriptional activity of the ER, which is independent of E2. Moreover, we demonstrated that CYR61 co-localizes with the ER in the nucleus and casually CYR61 transcriptional activity is regulated, at least in part by FOXO3a binding site. In search of the mechanism by which CYR61 that modulates hormonal response we discovered that CYR61 and FOXO3a interact in the presence of E2. This functional interplay among CYR61/ER/FOXO3a most likely plays a critical role in blocking hormone-response of breast cancer growth in vitro and in vivo. Furthermore, these studies demonstrate that CYR61 and FOXO3a are novel therapeutic targets to halt hormone-independent breast carcinomas. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5145.

Abstract The growth factor Heregulin (HRG) is expressed in about 30% of breast cancer tumors, and induces tumorigenicity and metastasis of breast cancer cells. We have demonstrated previously that HRG overexpression renders breast cancer cells resistance to the microtubule-interfering agent Taxol, a drug of choice for the treatment of metastatic breast cancer. The mechanism by which HRG induces Taxol resistance is largely unknown. It is also known that triple negative breast cancer tumors do express high levels of HRG and unfortunately they do not respond to HRG. Our studies were aimed at targeting HRG with the goal of achieving a therapeutic target as well as restoring the response to Taxol, while preventing the formation of metastasis. Thus, we knocked-down HRG expression in three different breast cancer cell lines: MDA-MB-23, HS578T and BT549. Our data demonstrates that HRG expression is an absolute requirement for the anchorage-independent growth for triple negative breast cancer cells, since none of the breast cancer cells MDA-MB-231, HS578T and BT549 stable expressing the silencing (shRNA) for HRG, were capable of forming colony in soft agar. Furthermore, these cells, not only no longer were not anchorage-independent were no longer resistant to Taxol, to the contrary the shRNA/HRG cells were exquisitely sensitive to Taxol, to induce growth inhibition and apoptosis. More importantly, we observed that the disorganized structured observed in 3D matrigel culture observed for triple negative cells, was completely abolished once HRG was knockdown and a very organized structure. These characteristics resembled an EMT (epithelial-mesenchymal epithelial transition (MET). This should be deemed a potential target in developing therapies for triple negative breast carcinomas. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1142.

Abstract CYR61 render human breast cancer cells highly resistance to the microtubule-interfering agent Taxol, a drug of choice for the treatment of metastatic breast cancer. The angiogenic factor CYR61 and its receptor avβ3 are markedly up-regulated in very aggressive breast carcinomas. Integrin signaling has been shown to modulate cancer cell responses to chemotherapy agents. Thus, the signal transduction pathways initiated by integrin may be a potential target for inhibiting cell survival during cytotoxic drug exposure. However, the molecular mechanism for CYR61-induces cytoprotection still unknown. Our data demonstrates that functional blockade of avβ3 with a synthetic chemical peptidomimetic based upon the αvβ3 the RGD (Arg-Gly-Asp) motif, is specifically cytotoxic towards CYR61-overexpressing breast cancer cells and that pharmacological interference of the CYR61/αvβ3 interaction restores Taxol efficacy. This data suggests that a previously unrecognized CYR61/αvβ3-driven cellular signaling actively modulates cell growth, apoptosis and chemosensitivity. To better understand the mechanism by which CYR61 induces Taxol resistance, we studied a series of molecular events and reveal that CYR61 prevents Taxol induction of p53 accumulation, blocks p21WAF1/CIP1 overexpression, and furthermore we demonstrated that CYR61 induces JNK activation. These observations suggest that increased expression of CYR61 could promote a chemoresistance by suppressing a specific pro-apoptotic signaling while still given chemotherapeutic treatments to induce cell damage. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1139.

Abstract Obesity and black race have been associated with excess risk of multiple myeloma. The association of obesity with monoclonal gammopathy of undetermined significance (MGUS) is unknown. Further, it is not known whether the increased risk of multiple myeloma and MGUS in blacks is related to socioeconomic status, genetic susceptibility, or both. We screened 1000 black and 996 white women (range, 40-79 years) of similar socioeconomic status for MGUS; the aim of the study was to assess MGUS risk in relation to obesity and race. A total of 39 (3.9%) blacks and 21 (2.1%) whites had MGUS. On multivariate analysis, obesity (odds ratio [OR] = 1.8; P = .04), black race (OR = 1.8; P = .04), and increasing age (> 55 vs < 43 years; OR = 2.5; P = .03) were independently associated with an excess risk of MGUS. Our findings support the hypothesis that obesity is etiologically linked to myelomagenesis. The 2-fold excess of MGUS among blacks compared with whites of similar socioeconomic status supports a role for susceptibility genes in MGUS.

A recently identified variant within the fat mass and obesity-associated ( FTO ) gene is carried by 46% of Western Europeans and is associated with an ~1.2 kg higher weight, on average, in adults and an ~1 cm greater waist circumference. With >1 billion overweight and 300 million obese persons worldwide, it is crucial to understand the implications of carrying this very common allele for the health of our aging population. FTO is highly expressed in the brain and elevated body mass index (BMI) is associated with brain atrophy, but it is unknown how the obesity-associated risk allele affects human brain structure. We therefore generated 3D maps of regional brain volume differences in 206 healthy elderly subjects scanned with MRI and genotyped as part of the Alzheimer's Disease Neuroimaging Initiative. We found a pattern of systematic brain volume deficits in carriers of the obesity-associated risk allele versus noncarriers. Relative to structure volumes in the mean template, FTO risk allele carriers versus noncarriers had an average brain volume difference of ~8% in the frontal lobes and 12% in the occipital lobes—these regions also showed significant volume deficits in subjects with higher BMI. These brain differences were not attributable to differences in cholesterol levels, hypertension, or the volume of white matter hyperintensities; which were not detectably higher in FTO risk allele carriers versus noncarriers. These brain maps reveal that a commonly carried susceptibility allele for obesity is associated with structural brain atrophy, with implications for the health of the elderly.