Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

ErbB2 targeted therapies represent an attractive strategy in breast cancer. Herceptin, an anti-ErbB2 monoclonal antibody, is an approved treatment for patients with ErbB2-overexpressing breast cancers. ErbB2 signaling can also be blocked using small molecule tyrosine kinase inhibitors, like Lapatinib, that compete with ATP for binding at the ErbB2 catalytic kinase domain. The principal adverse event attributable to Herceptin is cardiac toxicity. Data from clinical trials show that, unlike Herceptin, Lapatinib may have reduced cardiac toxicity. This study was conducted to elucidate pathways which may contribute to cardiac toxicity or survival using Lapatinib and Herceptin. Our results show that treatments directed to ErbB1/2 receptors using GW-2974 (a generic ErbB1/2 inhibitor) activated AMPK, a key regulator in mitochondrial energy production pathways in human cardiac cells and cancer cells. Although Herceptin downregulates tumor survival pathways, AMPK fails to be activated in tumor and cardiac cells. When treated in combination with TNFalpha, a known cytokine associated with cardiac toxicity, GW-2974 protected cardiac cells from cell death whereas Herceptin contributed to TNFalpha-induced cellular killing. Since activity of AMPK in cardiac cells is associated with stress induced survival in response to cytokines or energy depletion, cardiac toxicity by Herceptin may be a consequence of failure to induce stress-related survival mechanisms. Thus, the ability to activate AMPK after treatment with tyrosine kinase inhibitors may be a crucial factor for increased efficacy against the tumor and decreased risk of cardiomyopathy.
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PMID:Activation of AMPK is necessary for killing cancer cells and sparing cardiac cells. 1859 1

Fatty Acid Synthase (FASN), a 250-kDa cytosolic multi-enzyme catalyzing eukaryotic de novo FA biogenesis, unexpectedly localizes in cancer cell culture supernatants and in the blood of cancer patients. High levels of "extracellular FASN" have recently been found in supernatants from Hepatitis C Virus-infected liver cells. The ultimate mechanism regulating FASN release, however, remained completely undefined. When the AMPK-activating drug AICAR was used to simulate an elevated AMP/ATP ratio in breast cancer cells, ELISA-based analyses revealed that extracellular FASN dramatically augmented in a dose- and time-dependent manner. Immunoblotting procedures using a battery of anti-FASN antibodies further confirmed that, in response to AMPK activation, FASN protein is depleted from the cytosol to accumulate as different FASN isoforms in the extracellular milieu. siRNA-induced blockade of AMPK expression largely attenuated AICAR-promoted FASN release. FASN release might represent a previously unrecognized mechanism through which AMPK monitor and restores cellular energy state in response to increasing AMP/ATP ratios.
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PMID:AMPK-sensed cellular energy state regulates the release of extracellular Fatty Acid Synthase. 1903 40

Population studies have revealed that treatment with the antidiabetic drug metformin significantly associates with reduced breast cancer risk. Animal studies have shown that metformin suppresses the development of mammary carcinomas in transgenic female mice carrying a HER2 oncogene, but not that of spontaneous tumors. We herein demonstrate that HER2 oncoprotein itself may represent a key cellular target involved in the anti-breast cancer actions of metformin. First, ectopical overexpression of HER2 oncogene significantly enhances metformin-induced breast cancer cell growth inhibition. Second, metformin treatment drastically downregulates HER2 protein levels (up to 85% reduction) in a dose- and time-dependent manner. Metformin-induced inhibition of HER2 take places regardless the molecular mechanism contributing to HER2 overexpression (i.e., human HER2 cDNA exogenously driven by a viral promoter and naturally occurring endogenous HER2 gene amplification). Mechanistically, metformin-induced suppression of HER2 overexpression appears to occur via direct (AMPK-independent) inhibition of p70S6K1 activity. Compound C- and small interference RNA (siRNA)-induced blockade of AMPK activity/expression fail to prevent the anti-HER2 effect of metformin while AMPK hyperactivation following exposure to the AMP analog AICAR is not sufficient to downregulate HER2 expression. HER2-positive breast cancer cells transfected with p70S6K1 siRNA become completely refractory to metformin-induced HER2 suppression. Of note, co-incubation with agents that block reactive oxygen species (ROS) production (e.g., N-acetylcysteine) dramatically enhanced the ability of metformin to decrease HER2 expression. From the perspective of chemoprevention, these findings altogether suggest that metformin might exert a protective mostly confined to the HER2-positive breast cancer subtype. From the perspective of intervention, the presence/absence of molecular hallmarks such as HER2 overexpression and/or p70S6K1 hyperactivation might dictate alternative responses in metformin-based treatment of early breast cancer. The importance of mTOR/p70S6K1-sensed ROS status at mediating the anti-oncogenic effects of metformin might represent a previously unrecognized linkage molecularly connecting its anti-aging and anti-cancer actions.
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PMID:The antidiabetic drug metformin suppresses HER2 (erbB-2) oncoprotein overexpression via inhibition of the mTOR effector p70S6K1 in human breast carcinoma cells. 1910 26

AMPK (AMP-activated protein kinase) is highly conserved in eukaryotes, where it functions primarily as a sensor of cellular energy status. Recent studies indicate that AMPK activation strongly suppresses cell proliferation in non-malignant cells as well as in tumor cells. In this study, quercetin activated AMPK in MCF breast cancer cell lines and HT-29 colon cancer cells, and this activation of AMPK seemed to be closely related to a decrease in COX-2 expression. The application of a COX-2 inhibitor or cox-2-/- cells supported the idea that AMPK is an upstream signal of COX-2, and is required for the anti-proliferatory and pro-apoptotic effects of quercetin. The suppressive or growth inhibitory effects of quercetin on COX-2 were abolished by treating cancer cells with an AMPK inhibitor Compound C. These results suggest that AMPK is crucial to the anti-cancer effect of quercetin and that the AMPK-COX-2 signaling pathway is important in quercetin-mediated cancer control.
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PMID:AMP kinase/cyclooxygenase-2 pathway regulates proliferation and apoptosis of cancer cells treated with quercetin. 1929 39

Low serum levels of adiponectin are a high risk factor for various types of cancer. Although adiponectin inhibits proliferation and metastasis of breast cancer cells, the underlying molecular mechanisms remain obscure. In this study, we show that adiponectin-activated AMPK reduces the invasiveness of MDA-MB-231 cells by stimulating dephosphorylation of AKT by increasing protein phosphatase 2A (PP2A) activity. Among the various regulatory B56 subunits, B56gamma was directly phosphorylated by AMPK at Ser(298) and Ser(336), leading to an increase of PP2A activity through dephosphorylation of PP2Ac at Tyr(307). We also show that both the blood levels of adiponectin and the tissue levels of PP2A activity were decreased in breast cancer patients and that the direct administration of adiponectin into tumor tissues stimulates PP2A activity. Taken together, these findings show that adiponectin, derived from adipocytes, negatively regulates the invasiveness of breast cancer cells by activating the tumor suppressor PP2A.
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PMID:Adiponectin-activated AMPK stimulates dephosphorylation of AKT through protein phosphatase 2A activation. 1936 11

Triple negative (TN) breast cancer is more frequent in women who are obese or have type II diabetes, as well as young women of color. These cancers do not express receptors for the steroid hormones estrogen or progesterone, or the type II receptor tyrosine kinase (RTK) Her-2 but do have upregulation of basal cytokeratins and the epidermal growth factor receptor (EGFR). These data suggest that aberrations of glucose and fatty acid metabolism, signaling through EGFR and genetic factors may promote the development of TN cancers. The anti-type II diabetes drug metformin has been associated with a decreased incidence of breast cancer, although the specific molecular subtypes that may be reduced by metformin have not been reported. Our data indicates that metformin has unique anti-TN breast cancer effects both in vitro and in vivo. It inhibits cell proliferation (with partial S phase arrest), colony formation and induces apoptosis via activation of the intrinsic and extrinsic signaling pathways only in TN breast cancer cell lines. At the molecular level, metformin increases P-AMPK, reduces P-EGFR, EGFR, P-MAPK, P-Src, cyclin D1 and cyclin E (but not cyclin A or B, p27 or p21), and induces PARP cleavage in a dose- and time-dependent manner. These data are in stark contrast to our previously published biological and molecular effects of metformin on luminal A and B, or Her-2 type breast cancer cells. Nude mice bearing tumor xenografts of the TN line MDA-MB-231, treated with metformin, show significant reductions in tumor growth (p = 0.0066) and cell proliferation (p = 0.0021) as compared to untreated controls. Metformin pre-treatment, before injection of MDA-MB-231 cells, results in a significant decrease in tumor outgrowth and incidence. Given the unique anti-cancer activity of metformin against TN disease, both in vitro and in vivo, it should be explored as a therapeutic agent against this aggressive form of breast cancer.
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PMID:Metformin induces unique biological and molecular responses in triple negative breast cancer cells. 1971 81

We previously identified a SNF1/AMPK-related protein kinase, Hunk, from a mammary tumor arising in an MMTV-neu transgenic mouse. The function of this kinase is unknown. Using targeted deletion in mice, we now demonstrate that Hunk is required for the metastasis of c-myc-induced mammary tumors, but is dispensable for normal development. Reconstitution experiments revealed that Hunk is sufficient to restore the metastatic potential of Hunk-deficient tumor cells, as well as defects in migration and invasion, and does so in a manner that requires its kinase activity. Consistent with a role for this kinase in the progression of human cancers, the human homologue of Hunk is overexpressed in aggressive subsets of carcinomas of the ovary, colon, and breast. In addition, a murine gene expression signature that distinguishes Hunk-wild type from Hunk-deficient mammary tumors predicts clinical outcome in women with breast cancer in a manner consistent with the pro-metastatic function of Hunk in mice. These findings identify a direct role for Hunk kinase activity in metastasis and establish an in vivo function for this kinase.
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PMID:The Snf1-related kinase, Hunk, is essential for mammary tumor metastasis. 1971 24

The topical application of TPA (12-O-tetradecanoylphorbol-13-acetate) to animal skin or direct treatment of TPA to cell cultures leads to inflammatory responses by enhancing cyclooxygenase 2 (COX-2) expression, and specific COX-2 inhibitors counteract this kind of inflammatory response. Furthermore, suppression of these inflammatory events by dietary-origin chemopreventive agents can provide a potential strategy to control carcinogenesis. In this in vivo study, the mammary glands of mature female rats were treated with TPA, and then the effects of genistein alone or in combination with capsaicin on suppression of inflammatory responses were examined. The combined effects of genistein and capsaicin on COX-2, pJNK, pERK, and pp38 expressions were additive or nonadditive, depending on signals tested. In vitro MCF-7 breast cancer cells, the apoptotic bodies as shown with Hoechst 33342 dye, exhibited a synergistic effect between genistein and capsaicin. The abilities of genistein alone or in combination with capsaicin in inhibiting breast cancer cell proliferation through the modulation of AMPK and COX-2 were tested. AMPK activation by genistein in combination with capsaicin is critical for inhibiting COX-2. We propose that genistein in combination with capsaicin exerts anti-inflammatory and anticarcinogenic properties through the modulation of AMPK and COX-2 and possibly various mitogen-activated protein kinases synergistically or nonsynergistically.
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PMID:Anti-inflammatory and anticarcinogenic effect of genistein alone or in combination with capsaicin in TPA-treated rat mammary glands or mammary cancer cell line. 1972 84

The LKB1 serine-threonine kinase is a tumor suppressor that is inactivated in a large number of sporadic human lung non-small cell carcinomas (NSCLCs) and cervical cancers. Genetic deletion of LKB1 in various mouse tissues results in tumorigenesis, and loss of LKB1 increases metastasis in a mouse model of NSCLC. LKB1 directly activates a family of 14 kinases related to AMPK [adenosine monophosphate (AMP)-activated protein kinase] to control cell metabolism, growth, and polarity, though which of these are critical to its tumor suppressor functions remain undefined. The LKB1-dependent kinase SIK1 (salt-inducible kinase 1) has now been identified as a key modulator of anoikis (apoptosis induced by cell detachment) and transformation in culture, and its modulation of the tumor suppressor p53 controls metastasis in transplanted tumor cells. Reduced SIK1 expression is correlated with poor prognosis in two large human breast cancer data sets. These findings suggest that SIK1 is a key upstream regulator of p53-dependent anoikis that may be targeted in tumorigenesis.
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PMID:Tumor suppression by LKB1: SIK-ness prevents metastasis. 1972 60

Type 2 diabetes is associated with a higher risk of cancer, which appears more obvious since the reduction of cardiovascular mortality. All glucose-lowering oral agents do not have the same impact on cancer: the risk is increased with sulfonylureas and decreased with metformin (and glitazones). Numerous epidemiological observational and case-control studies showed that metformin is associated with a lower incidence of cancer and a lower cancer-related death rate. A dose-response relationship and a relation between duration of prior treatment with metformin and the protective effect against cancer have been reported. Mechanisms involved are the activation of the AMPK enzyme and the inhibition of the mTOR pathway. Studies with metformin are ongoing in the field of oncology, especially as adjunct to treatment of breast cancer.
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PMID:[Anti-cancer activity of metformin: new perspectives for an old drug]. 2085 15


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