Browsing by Author "Dopazo, Ana"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- Harmine and Piperlongumine revert TRIB2-mediated drug resistancePublication . Machado, Susana; Silva, Andreia; De Sousa-Coelho, Ana Luísa; Duarte, Isabel; Grenho, Inês; Santos, Bruno F; Mayoral-Varo, Victor; Megias, Diego; Sánchez-Cabo, Fátima; Dopazo, Ana; Ferreira, Bibiana I.; Link, WolfgangTherapy resistance is responsible for most relapses in patients with cancer and is the major challenge to improving the clinical outcome. The pseudokinase Tribbles homologue 2 (TRIB2) has been characterized as an important driver of resistance to several anti-cancer drugs, including the dual ATP-competitive PI3K and mTOR inhibitor dactolisib (BEZ235). TRIB2 promotes AKT activity, leading to the inactivation of FOXO transcription factors, which are known to mediate the cell response to antitumor drugs. To characterize the downstream events of TRIB2 activity, we analyzed the gene expression profiles of isogenic cell lines with different TRIB2 statuses by RNA sequencing. Using a connectivity map-based computational approach, we identified drug-induced gene-expression profiles that invert the TRIB2-associated expression profile. In particular, the natural alkaloids harmine and piperlongumine not only produced inverse gene expression profiles but also synergistically increased BEZ235-induced cell toxicity. Importantly, both agents promote FOXO nuclear translocation without interfering with the nuclear export machinery and induce the transcription of FOXO target genes. Our results highlight the great potential of this approach for drug repurposing and suggest that harmine and piperlongumine or similar compounds might be useful in the clinic to overcome TRIB2-mediated therapy resistance in cancer patients.
- A novel phosphatidylinositol 3-kinase (PI3K) inhibitor directs a potent FOXO-dependent, p53-independent cell cycle arrest phenotype characterized by the differential induction of a subset of FOXO-regulated genesPublication . Hill, Richard; Kalathur, Ravi Kiran Reddy; Callejas, Sergio; Colaço, Laura; Brandão, Ricardo; Serelde, Beatriz; Cebriá, Antonio; Blanco-Aparicio, Carmen; Pastor, Joaquín; Futschik, Matthias; Dopazo, Ana; Link, WolfgangIntroduction: The activation of the phosphoinositide 3-kinase (PI3K)/AKT signalling pathway is one the most frequent genetic events in breast cancer, consequently the development of PI3K inhibitors has attracted much attention. Here we evaluate the effect of PI3K inhibition on global gene expression in breast cancer cells. Methods: We used a range of methodologies that include in silico compound analysis, in vitro kinase assays, cell invasion assays, proliferation assays, genome-wide transcription studies (Agilent Technologies full genome arrays), gene set enrichment analysis, quantitative real-time PCR, immunoblotting in addition to chromatin immunoprecipitation. Results: We defined the physico-chemical and the biological properties of ETP-45658, a novel potent PI3K inhibitor. We demonstrated that ETP-45658 potently inhibited cell proliferation within a broad range of human cancer cells, most potently suppressing the growth of breast cancer cells via inhibiting cell cycle. We show that this response is Forkhead box O (FOXO) protein dependent and p53 independent. Our genome-wide microarray analysis revealed that the cell cycle was the most affected biological process after exposure to ETP-45658 (or our control PI3K inhibitor PI-103), that despite the multiple transcription factors that are regulated by the PI3K/AKT signalling cascade, only the binding sites for FOXO transcription factors were significantly enriched and only a subset of all FOXO-dependent genes were induced. This disparity in gene transcription was not due to differential FOXO promoter recruitment. Conclusions: The constitutive activation of PI3Ks and thus the exclusion of FOXO transcription factors from the nucleus is a key feature of breast cancer. Our results presented here highlight that PI3K inhibition activates specific FOXO-dependent genes that mediate cell cycle arrest in breast cancer cells.
- Retraction note: TRIB2 confers resistance to anti-cancer therapy by activating the serine/threonine protein kinase AKTPublication . Hill, Richard; Madureira, Patricia; Ferreira, Bibiana; Baptista, Ines; Machado, Susana; Colaҫo, Laura; dos Santos, Marta; Liu, Ningshu; Dopazo, Ana; Ugurel, Selma; Adrienn, Angyal; Kiss-Toth, Endre; Isbilen, Murat; Gure, Ali O.; Link, WolfgangThe authors have retracted this article as it has come to their attention that several images were inappropriately processed and duplicated in multiple figures. In particular, the data were duplicated, and in some cases inverted, across several panels in Figures 2c, 2b, 3d and Supplementary Figure 5. Erroneous data were also included in Figure 2e, Supplementary Figure 1 and Supplementary Figure 8. We apologize to the scientific community for any confusion this article may have caused. Richard Hill, Patricia Madureira, Bibiana I. Ferreira, Susana Machado, Ana Dopazo, Selma Ugurel, Endre Kiss-Toth, Murat isbilen and Wolfgang Link agree with this retraction. Inês Baptista, Laura Colaço, Marta dos Santos, Ningshu Liu, Angyal Adrienn and Ali O. Gure have not responded to correspondence from the Publisher about this retraction.
- TRIB2 confers resistance to anti-cancer therapy by activating the serine/threonine protein kinase AKTPublication . Hill, Richard; Madureira, Patricia; Ferreira, Bibiana; Baptista, Inês; Machado, S.; Colaco, Laura; dos Santos, Marta; Liu, Ningshu; Dopazo, Ana; Ugurel, Selma; Adrienn, Angyal; Kiss-Toth, Endre; Isbilen, Murat; Gure, Ali O.; Link, WolfgangIntrinsic and acquired resistance to chemotherapy is the fundamental reason for treatment failure for many cancer patients. The identification of molecular mechanisms involved in drug resistance or sensitization is imperative. Here we report that tribbles homologue 2 (TRIB2) ablates forkhead box O activation and disrupts the p53/MDM2 regulatory axis, conferring resistance to various chemotherapeutics. TRIB2 suppression is exerted via direct interaction with AKT a key signalling protein in cell proliferation, survival and metabolism pathways. Ectopic or intrinsic high expression of TRIB2 induces drug resistance by promoting phospho-AKT (at Ser473) via its COP1 domain. TRIB2 expression is significantly increased in tumour tissues from patients correlating with an increased phosphorylation of AKT, FOXO3a, MDM2 and an impaired therapeutic response. This culminates in an extremely poor clinical outcome. Our study reveals a novel regulatory mechanism underlying drug resistance and suggests that TRIB2 functions as a regulatory component of the PI3K network, activating AKT in cancer cells.