Doxorubicin upregulates CXCR4 via miR-200c/ZEB1-dependent mechanism in human cardiac mesenchymal progenitor cells.

Doxorubicin (DOXO) treatment is limited by its cardiotoxicity, since it causes cardiac-progenitor-cell depletion. Although the cardioprotective role of the stromal cell-derived factor-1/C-X-C chemokine receptor type 4 (SDF1/CXCR4) axis is well established, its involvement during DOXO-induced cardiotoxicity has never been investigated. We showed that in a mouse model of DOXO-induced cardiomyopathy, CXCR4 <sup>+</sup> cells were increased in response to DOXO, mainly in human cardiac mesenchymal progenitor cells (CmPC), a subpopulation with regenerative potential. Our in vitro results showed a CXCR4 induction after 24 h of DOXO exposure in CmPC. SDF1 administration protected from DOXO-induced cell death and promoted CmPC migration. CXCR4 promoter analysis revealed zinc finger E-box binding homeobox 1 (ZEB1) binding sites. Upon DOXO treatment, ZEB1 binding decreased and RNA-polymerase-II increased, suggesting a DOXO-mediated transcriptional increase in CXCR4. Indeed, DOXO induced the upregulation of miR-200c, that directly targets ZEB1. SDF1 administration in DOXO-treated mice partially reverted the adverse remodeling, decreasing left ventricular (LV) end diastolic volume, LV ejection fraction and LV anterior wall thickness in diastole, recovering LV end systolic pressure and reducing±dP/dt. Moreover, in vivo administration of SDF1 partially reverted DOXO-induced miR-200c and p53 protein upregulation in mouse hearts. In addition, downmodulation of ZEB1 mRNA and protein by DOXO was significantly increased by SDF1. In keeping, p21 mRNA, that is induced by p53 and inhibited by ZEB1, is induced by DOXO treatment and is decreased by SDF1 administration. This study showed new players of the DOXO-induced cardiotoxicity, that can be exploited to ameliorate DOXO-associated cardiomyopathy

Protein alterations associated with temozolomide resistance in subclones of human glioblastoma cell lines

Temozolomide (TMZ) is the standard chemotherapeutic agent for human malignant glioma, but intrinsic or acquired chemoresistance represents a major obstacle to successful treatment of this highly lethal group of tumours. Obtaining better understanding of the molecular mechanisms underlying TMZ resistance in malignant glioma is important for the development of better treatment strategies. We have successfully established a passage control line (D54-C10) and resistant variants (D54-P5 and D54-P10) from the parental TMZ-sensitive malignant glioma cell line D54-C0. The resistant sub-cell lines showed alterations in cell morphology, enhanced cell adhesion, increased migration capacities, and cell cycle arrests. Proteomic analysis identified a set of proteins that showed gradual changes in expression according to their 50% inhibitory concentration (IC50). Successful validation was provided by transcript profiling in another malignant glioma cell line U87-MG and its resistant counterparts. Moreover, three of the identified proteins (vimentin, cathepsin D and prolyl 4-hydroxylase, beta polypeptide) were confirmed to be upregulated in high-grade glioma. Our data suggest that acquired TMZ resistance in human malignant glioma is associated with promotion of malignant phenotypes, and our reported molecular candidates may serve not only as markers of chemoresistance but also as potential therapeutic targets in the treatment of TMZ-resistant human malignant glioma, providing a platform for future investigations

miR-210: fine-tuning the hypoxic response

Hypoxia is a central component of the tumor microenvironment and represents a major source of therapeutic failure in cancer therapy. Recent work has provided a wealth of evidence that noncoding RNAs and, in particular, microRNAs, are significant members of the adaptive response to low oxygen in tumors. All published studies agree that miR-210 specifically is a robust target of hypoxia-inducible factors, and the induction of miR-210 is a consistent characteristic of the hypoxic response in normal and transformed cells. Overexpression of miR-210 is detected in most solid tumors and has been linked to adverse prognosis in patients with soft-tissue sarcoma, breast, head and neck, and pancreatic cancer. A wide variety of miR-210 targets have been identified, pointing to roles in the cell cycle, mitochondrial oxidative metabolism, angiogenesis, DNA damage response, and cell survival. Additional microRNAs seem to be modulated by low oxygen in a more tissue-specific fashion, adding another layer of complexity to the vast array of protein-coding genes regulated by hypoxia

Cyclin D1 degradation enhances endothelial cell survival upon oxidative stress

The understanding of endothelial cell responses to oxidative stress may provide insights into aging mechanisms and into the pathogenesis of numerous cardiovascular diseases. In this study, we examined the regulation and the functional role of cyclin D1, a crucial player in cell proliferation and survival. On H2O2 treatment, endothelial cells showed a rapid down-modulation of cyclin D1. Other D-cyclins were similarly regulated, and this decrease was also observed after exposure to other oxidative stress-inducing stimuli, namely 1,3-bis (2 chloroethyl)-1 nitrosourea treatment and ischemia. H2O2 treatment induced cyclin D1 ubiquitination followed by proteasome degradation. Phospholipase C inhibition prevented cyclin D1 degradation, and its activation triggered cyclin D1 down-modulation in the absence of oxidative stress. Activated phospholipase C generates inositol-1,4,5-trisphosphate (IP3) and Ca2+ release from internal stores. We found that both IP3-receptor inhibition and intracellular Ca2+ chelation prevented cyclin D1 degradation induced by oxidative stress. Furthermore, Ca2+ increase was transduced by Ca2+/calmodulin-dependent protein kinase (CaMK). In fact, H2O2 stimulated CaMK activity, CaMK inhibitors prevented H2O2-induced cyclin D1 down-modulation, and CaMK overexpression induced cyclin D1 degradation. Finally, overriding of cyclin D1 down-modulation via its forced overexpression or via CaMK inhibition increased cell sensitivity to H2O2-induced apoptotic cell death. Thus, cyclin D1 degradation enhances endothelial cell survival on oxidative stress

The seco-taxane IDN5390 is able to target class III beta-tubulin and to overcome paclitaxel resistance.

9reservedmixedFERLINI C; RASPAGLIO G; MOZZETTI S; CICCHILLITTI L; FILIPPETTI F; GALLO D; FATTORUSSO C; G. CAMPIANI; SCAMBIA G.Ferlini, C; Raspaglio, G; Mozzetti, S; Cicchillitti, L; Filippetti, F; Gallo, D; Fattorusso, C; Campiani, Giuseppe; Scambia, G

The seco-taxane IDN5390 is able to target class III β-tubulin and to overcome paclitaxel resistance.

A prominent mechanism of drug resistance to taxanes is the overexpression of class III β-tabulin. The seco-taxane IDN5390 was chosen for its selective activity in paclitaxel-resistant cells with an overexpression of class III β-tubulin. Moreover, the combined treatment paclitaxel/IDN5390 yielded a strong synergism, which was also evident in cell-free tubulin polymerization assays. In the presence of an anti-class III β-tubulin as a blocking antibody, tubulin polymerization induced by paclitaxel and IDN5390 was enhanced and not affected, respectively, whereas synergism was abolished, thereby indicating that IDN5390 activity is not modulated by class III β-tabulin levels. Such properties can be explained by talcing into consideration the composition of class III β-tubulin paclitaxel binding site; in fact, Ser277 interacting with paclitaxel C group in class I is replaced by an Arginine in class III. IDN5390 that has an open and flexible C ring and an acidic α-unsatarated enol-keton moiety better fits with class III β-tubulin than paclitaxel at the binding site. Taken altogether, these findings indicate that the concomitant treatment IDN5390/paclitaxel is able to successfully target class I and III β-tubulin and the combined use of two taxanes with diverse spectrum activity against tubulin isotypes could represent a novel approach to overcome paclitaxel resistanc