Aleksandra Filipovic

Imperial College London, London, ENG, United Kingdom

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Publications (9)71.38 Total impact

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    ABSTRACT: Breast cancer accounts for more than 450,000 deaths per year worldwide. Discovery of novel therapeutic targets that will allow patient-tailored treatment of this disease is an emerging area of scientific interest. Recently, nicastrin has been identified as one such therapeutic target. Its overexpression is indicative of worse overall survival in the estrogen-receptor-negative patient population. In this paper, we analyze data from a large invasive breast carcinoma study and confirm nicastrin amplification. In search for genes that are co-amplified with nicastrin, we identify a potential novel breast cancer-related amplicon located on chromosome 1. Furthermore, we search for "influential interactors," i.e., genes that interact with a statistically significantly high number of genes which are co-amplified with nicastrin, and confirm their involvement in this female neoplasm. Among the influential interactors, we find genes which belong to the core diseasome (a recently identified therapeutically relevant set of genes which is known to drive disease formation) and propose that they might be important for breast cancer onset, and serve as its novel therapeutic targets. Finally, we identify a pathway that may play a role in nicastrin's amplification process and we experimentally confirm downstream signaling mechanism of nicastrin in breast cancer cells.
    Breast Cancer Research and Treatment 12/2013; · 4.47 Impact Factor
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    ABSTRACT: Background:We have previously identified kinase suppressor of ras-1 (KSR1) as a potential regulatory gene in breast cancer. KSR1, originally described as a novel protein kinase, has a role in activation of mitogen-activated protein kinases. Emerging evidence has shown that KSR1 may have dual functions as an active kinase as well as a scaffold facilitating multiprotein complex assembly. Although efforts have been made to study the role of KSR1 in certain tumour types, its involvement in breast cancer remains unknown.Methods:A quantitative mass spectrometry analysis using stable isotope labelling of amino acids in cell culture (SILAC) was implemented to identify KSR1-regulated phosphoproteins in breast cancer. In vitro luciferase assays, co-immunoprecipitation as well as western blotting experiments were performed to further study the function of KSR1 in breast cancer.Results:Of significance, proteomic analysis reveals that KSR1 overexpression decreases deleted in breast cancer-1 (DBC1) phosphorylation. Furthermore, we show that KSR1 decreases the transcriptional activity of p53 by reducing the phosphorylation of DBC1, which leads to a reduced interaction of DBC1 with sirtuin-1 (SIRT1); this in turn enables SIRT1 to deacetylate p53.Conclusion:Our findings integrate KSR1 into a network involving DBC1 and SIRT1, which results in the regulation of p53 acetylation and its transcriptional activity.British Journal of Cancer advance online publication, 15 October 2013; doi:10.1038/bjc.2013.628 www.bjcancer.com.
    British Journal of Cancer 10/2013; · 5.08 Impact Factor
  • Aleksandra Filipovic, Justin Stebbing, Georgios Giamas
    The Lancet Oncology 06/2013; 14(7):579-580. · 25.12 Impact Factor
  • J Stebbing, A Filipović, G Giamas
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    ABSTRACT: Claudins are integral structural and functional components of apical cell adhesions (tight junctions). Loss of such adhesions has been associated with malignant transformation, a process most often accompanied by a concomitant loss of claudin expression. A growing body of evidence reveals the highly contextual upregulation of claudin expression in certain cancer types, and moreover their relevance in promoting cancer cell invasion and metastatic progression. In this issue of Oncogene, Suh et al. reported on claudin-1 expression in hepatocellular carcinoma (HCC), including its role as a promoter of the epithelial-to-mesenchymal transition via the c-Abl/Raf/Ras/ERK signaling pathway. Considering the limited therapeutic options in HCC, evaluation of its role as a target merits further investigation.Oncogene advance online publication, 14 January 2013; doi:10.1038/onc.2012.591.
    Oncogene 01/2013; · 8.56 Impact Factor
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    ABSTRACT: Resistance to endocrine therapy in breast cancer is common. With the aim of discovering new molecular targets for breast cancer therapy, we have recently identified LMTK3 as a regulator of the estrogen receptor-alpha (ERα) and wished to understand its role in endocrine resistance. We find that inhibition of LMTK3 in a xenograft tamoxifen (Tam)-resistant (BT474) breast cancer mouse model results in re-sensitization to Tam as demonstrated by a reduction in tumor volume. A whole genome microarray analysis, using a BT474 cell line, reveals genes significantly modulated (positively or negatively) after LMTK3 silencing, including some that are known to be implicated in Tam resistance, notably c-MYC, HSPB8 and SIAH2. We show that LMTK3 is able to increase the levels of HSPB8 at a transcriptional and translational level thereby protecting MCF7 cells from Tam-induced cell death, by reducing autophagy. Finally, high LMTK3 levels at baseline in tumors are predictive for endocrine resistance; therapy does not lead to alteration in levels, whereas in patient's plasma samples, acquired LMTK3 gene amplification (copy number variation) was associated with relapse while receiving Tam. In aggregate, these data support a role for LMTK3 in both innate (intrinsic) and acquired (adaptive) endocrine resistance in breast cancer.Oncogene advance online publication, 6 August 2012; doi:10.1038/onc.2012.343.
    Oncogene 08/2012; · 8.56 Impact Factor
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    ABSTRACT: Interactions between kinases and the estrogen receptor α (ERα) are thought to be a critical signaling pathway in the majority of human breast cancers. We have recently identified a previously uncharacterized molecule, lemur tyrosine kinase-3 (LMTK3) as a prognostic and predictive oncogenic ERα regulator with a central role in endocrine resistance. Unusually this protein has undergone Darwinian positive selection between Chimpanzees and humans suggesting it may contribute to human susceptibility to ERα-positive tumors. Using over 600 European primary breast cancer cases, we wished to establish tumor characteristics associated with both cytoplasmic and nuclear LMTK3 expression, and then externally validate our observed European clinical outcomes with samples from Asian individuals receiving chemotherapy. Both nuclear and cytoplasmic expression correlated with tumor grade (P < 0.001) and in the Asian cohort, independent blinded analyses demonstrated that high basal LMTK3 expression was associated with advanced stage of primary breast cancers as well as decreased overall (P = 0.03) and disease-free survival (P = 0.006). In summary, higher LMTK3 expression is associated with more aggressive cancers. These data support our previous findings and suggest LMTK3 expression may be a reliable new biomarker in breast cancer.
    Breast Cancer Research and Treatment 06/2011; 132(2):537-44. · 4.47 Impact Factor
  • A Filipovic, G Giamas, J Stebbing
    Annals of Oncology 05/2011; 22(8):1700-2. · 7.38 Impact Factor
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    ABSTRACT: The tyrosine kinase receptor, HER2 is a crucial prognostic marker and therapeutic target for breast cancer; however, the downstream targets and biological effectors of HER2 remain unclear. We investigated the relationship between HER2 and the transcription factor FoxM1 in breast cancer. HER2 and FoxM1 expression levels were compared in breast carcinoma cell lines, paraffin-embedded breast cancer patient samples and at the mRNA level in purified breast epithelial cells. To further examine the relationship between HER2 and FoxM1 expression, we either overexpressed or siRNA-mediated depleted endogenous HER2 in breast cancer cell lines. Additionally, a mammary epithelium-targeted HER2 (neu) transgenic mouse model was also used to assess the effect of HER2 on FoxM1 levels. Furthermore, the effect of the HER2-tyrosine kinase inhibitor lapatinib on FoxM1 in HER2 positive breast cancer cells was investigated. HER2 protein levels directly correlated with FoxM1 expression in both breast carcinoma cell lines and paraffin-embedded breast cancer patient samples. Moreover, in purified breast epithelial cells, overexpression of HER2 was associated with high levels of FoxM1 mRNA, suggesting that the upregulation of FoxM1 expression is at least partially mediated transcriptionally. Furthermore, overexpression or ablation of endogenous HER2 resulted in parallel changes in FoxM1 expression. Critically, mammary epithelium-targeted HER2 mouse tumours also resulted in increased FoxM1 expression, suggesting that HER2 directed FoxM1 expression occurs in vivo and may be a critical downstream effector of HER2-targeting therapies. Indeed, treatment of breast cancer cells with lapatinib reduced FoxM1 expression at protein, mRNA and gene promoter levels. Moreover, analysis of normal and breast cancer patient samples revealed that elevated FoxM1 expression at protein and mRNA levels correlated with breast cancer development, but not significantly with cancer progression and survival. Our results indicate that the HER2 receptor regulates the expression of the FoxM1 transcription factor, which has a role in breast cancer development.
    International Journal of Oncology 08/2009; 35(1):57-68. · 2.66 Impact Factor
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    ABSTRACT: Gamma-secretase activity is vital for the transmembrane cleavage of Notch receptors and the subsequent migration of their intracellular domains to the nucleus. Notch overexpression has been associated with breast, colon, cervical and prostate cancers. We tested the effect of three different gamma-secretase inhibitors (GSIs) in breast cancer cells. One inhibitor (GSI1) was lethal to breast cancer cell lines at concentrations of 2 muM and above but had a minimal effect on the non-malignant breast lines. GSI1 was also cytotoxic for a wide variety of cancer cell lines in the NCI60 cell screen. GSI1 treatment resulted in a marked decrease in gamma-secretase activity and downregulation of the Notch signalling pathway with no effects on expression of the gamma-secretase components or ligands. Flow cytometric and western blot analyses indicated that GSI1 induces a G2/M arrest leading to apoptosis, through downregulation of Bcl-2, Bax and Bcl-XL. GSI1 also inhibited proteasome activity. Thus, the gamma-secretase inhibitor GSI1 has a complex mode of action to inhibit breast cancer cell survival and may represent a novel therapy in breast cancer.
    British Journal of Cancer 07/2009; 100(12):1879-88. · 5.08 Impact Factor