ALBERT

Description: Exosomes derived from mesenchymal stem cells are extracellular vesicles released to facilitate cell communication and function. Recently, polylactic acid (PLA), calcium silicates (CaSi), and dicalcium phosphate dihydrate (DCPD) have been used to produce bioresorbable functional mineral-doped porous scaffolds-through thermally induced phase separation technique, as materials for bone regeneration. The aim of this study was to investigate the effect of mineral-doped PLA-based porous scaffolds enriched with exosome vesicles (EVs) on osteogenic commitment of human adipose mesenchymal stem cells (hAD-MSCs). Two different mineral-doped scaffolds were produced: PLA-10CaSi-10DCPD and PLA-5CaSi-5DCPD. Scaffolds surface micromorphology was investigated by ESEM-EDX before and after 28 days immersion in simulated body fluid (HBSS). Exosomes were deposited on the surface of the scaffolds and the effect of exosome-enriched scaffolds on osteogenic commitment of hAD-MSCs cultured in proximity of the scaffolds has been evaluated by real time PCR. In addition, the biocompatibility was evaluated by direct-contact seeding hAD-MSCs on scaffolds surface-using MTT viability test. In both formulations, ESEM showed pores similar in shape (circular and elliptic) and size (from 10–30 µm diameter). The porosity of the scaffolds decreased after 28 days immersion in simulated body fluid. Mineral-doped scaffolds showed a dynamic surface and created a suitable bone-forming microenvironment. The presence of the mineral fillers increased the osteogenic commitment of hAD-MSCs. Exosomes were easily entrapped on the surface of the scaffolds and their presence improved gene expression of major markers of osteogenesis such as collagen type I, osteopontin, osteonectin, osteocalcin. The experimental scaffolds enriched with exosomes, in particular PLA-10CaSi-10DCPD, increased the osteogenic commitment of MSCs. In conclusion, the enrichment of bioresorbable functional scaffolds with exosomes is confirmed as a potential strategy to improve bone regeneration procedures.

Description: Abstract 233 Azacitidine, a DNA methyltransferase inhibitor currently used for the treatment of higher-risk myelodysplastic syndromes (MDS) patients, was shown to delay the evolution into acute myeloid leukemia (AML) and prolong overall survival (Fenaux P et al, Lancet Oncol 2009). In addition, azacitidine has recently been shown to potentially be a feasible and effective treatment even for patients with lower-risk MDS (Musto P et al, Cancer 2010). Lipid signalling pathways are involved in many important biological processes, such as cell growth, differentiation and apoptosis and play a role in the progression of MDS towards AML (Follo MY et al, J Cell Biochem 2010). Moreover, we recently demonstrated that phosphoinositide-phospholipase C beta1 (PI-PLCbeta1) promoter gene is hyper-methylated in higher-risk MDS and that azacitidine treatment can induce an increase in the level of PI-PLCbeta1 splicing variants as well as a down-regulation of activated Akt (Follo MY et al, Leukemia 2008; Follo MY et al, PNAS 2009). In fact, responding patients showed an increase in PI-PLCbeta1 expression in correlation with the therapeutic response, whereas their PI-PLCbeta1 promoter methylation was reduced. Furthermore, the decrease of promoter methylation anticipated the hematologic response, since the variations in PI-PLCbeta1 gene expression were observed prior to the clinical outcome. Stemming from these data, we further investigated the role of inositide signalling pathways during the epigenetic therapy, focusing on the effect of azacitidine on lipid signal transduction pathways in lower-risk MDS patients. The study included 25 patients (IPSS risk: low or intermediate-1) treated with azacitidine (75mg/m2 subcutaneous daily for 5 consecutive days every 28 days, for a total of 8 courses). For each patient we followed the effect of azacitidine in correlation to both PI-PLCbeta1 promoter methylation and gene expression, as well as the molecular profile of key molecules involved in the regulation of methylation processes, such as histone deacetylases (HDACs), methyl-CpG binding domain proteins (MBDs), and transcription factors correlated to hematopoietic stem cell differentiation and proliferation. Our results show that 8/25 (34%) of our lower-risk MDS patients, showing hematologic improvements after azacitidine therapy, had a significant increase in PI-PLCbeta1 expression, as compared with the amount of the pre-treatment period, thus confirming the involvement of this molecule in the response to demethylating agents. As for the remaining patients, mainly showing a stable disease, we observed slight increases or almost constant levels of PI-PLCbeta1 expression. Moreover, ongoing analyses are trying to disclose whether lower-risk MDS patients responding to azacitidine show a specific molecular epigenetic profile during the regulation of methylation processes. Taken together, our data suggest a correlation between azacitidine treatment and PI-PLCbeta1 signalling even in lower-risk MDS, thus hinting at a role for PI-PLCbeta1 in the evaluation of patients likely to respond to azacitidine and paving the way for the development of innovative therapeutic strategies in lower-risk MDS patients. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 4635 Nuclear inositide signalling pathways are involved in the MDS progression to AML. Indeed, in the last few years our group demonstrated not only that MDS cells can show alterations on PI-PLCbeta1 and Akt pathways, but also that Akt is inversely correlated with PI-PLCbeta1, therefore affecting MDS cell survival and differentiation. Lenalidomide has proven effectiveness in 70–80% low-risk MDS cases with del(5q), resulting in transfusion-independence with a rise in hemoglobin levels, suppression of the 5q clone, and improvement of bone marrow morphologic features. In particular, in del(5q) MDS, Lenalidomide probably acts by directly suppressing the dysplastic clone, while in non-del(5q) it might enhance an effective erythropoiesis, possibly via activation of the EPO signalling, which in turn is associated with PI-PLCgamma1 pathways. However, the exact molecular mechanisms underlying the effect of Lenalidomide in MDS cells are still not completely clarified. Interestingly, Lenalidomide might inhibit the phosphatase PP2A, whose gene is located in the common deleted region and which usually targets Akt. Indeed, Akt-dependent pathways are critical in low-risk MDS cells, which display a marked apoptosis and a low proliferation rate. In this study we examined four MDS patients treated with Lenalidomide, and compared them with four low-risk MDS patients (IPSS: Low or Int-1) who only received best supportive care. In our study, all of the patients treated with Lenalidomide were affected by del(5q) low-risk MDS (IPSS: Low or Int-1), with transfusion-dependent anemia, and had only received supportive care before undergoing Lenalidomide treatment. Clinically, all of the patients responded to Lenalidomide: one patient reached Complete Remission, whilst the other three patients showed erythroid Hematologic Improvement. In contrast, all of the patients who were treated only with best supportive care maintained a Stable Disease. As for the molecular effects of Lenalidomide on lipid signalling pathways, we analyzed the expression of critical molecules involved in both cell proliferation and differentiation, that is PI-PLCbeta1 and its downstream target Cyclin D3, as well as PI-PLCgamma1, which is linked with EPO signalling. Ongoing analyses are also trying to examine the effect of Lenalidomide on Akt phosphorylation and Globin genes, which are specifically associated with erythropoiesis. So far, our results indicate that, in our responder patients, both PI-PLCbeta1 and Cyclin D3 are not significantly affected by Lenalidomide, whereas PI-PLCgamma1 is specifically induced, as compared with both healthy subjects and low-risk MDS patients treated with supportive care. Overall, these findings hint at a specific activation of PI-PLCgamma1 signalling following Lenalidomide treatment, and possibly pave the way to larger investigations aiming to better understand the role of these pathways in the mechanism of action of Lenalidomide in del(5q) MDS. Disclosures: No relevant conflicts of interest to declare.

Description: Background and Rationale. Azacitidine (AZA) is a standard first-line therapy in high-risk MDS. Also its combination with Lenalidomide (LEN) has been tested, but its molecular effect is still under investigation. Here we analyzed the effect of AZA+LEN therapy on gene mutations and microRNA expression in MDS patients. Patients and Methods. This study included 44 high-risk MDS patients treated with AZA (75 mg/m2/day, days 1-5, sc) and LEN (10 mg/day, days 1-21, orally) every 4 weeks. Patients showing complete remission (CR), partial remission (PR) or any hematologic improvement were considered as responders, while patients showing stable disease or disease progression were considered as non responders. Molecular analyses were performed at baseline and during the therapy. Gene mutations were studied by an Illumina Cancer Myeloid Panel and an Ion Torrent specific panel, whereas microRNAs expression was assessed using an Affymetrix miRNA 4.0 array. Results. 34/44 patients were considered evaluable for response, with an overall response rate of 76.25% (26/34 cases). 13 patients showed a positive response within the 4th cycle (T4) and maintained it at T8; 9 patients showed a positive response within T4 and lost response at T8; 4 patients responded after T4 and maintained the response at T8; 8 patients never responded. Molecular analyses were performed on serial samples (baseline, T4 and T8) available for 30 patients. Results from the Illumina analysis on cancer myeloid genes showed that 3/30 cases had no mutations at all, all other cases showed mutations both at baseline and during the therapy. The most frequently mutated genes were ASXL1 (14 cases = 47%), TET2 (11 cases = 37%), RUNX1 (8 cases = 27%) and SRSF2 (5 cases = 17%). All samples with a decreasing variant allele frequency (VAF) had a favourable response at T8 (CR, marrow CR or PR), while none of the non responders showed a decreasing VAF. Ion Torrent analysis of 24 inositide-specific genes showed that all patients had mutations both at baseline and during the therapy. Interestingly, all patients responding at T4 and losing response at T8, as well as cases that did not respond, acquired the same 3 point mutations at T8, affecting respectively PIK3CD (D133E), AKT3 (D280G) and PLCG2 (Q548R) genes. Patients responding at T4 and losing response at T8 showed these mutations even at T4. Kaplan-Meier analyses revealed that the presence of these mutations was significantly associated with a decreased duration of therapy (39.5 vs 8.5 months; p

Description: An increasing number of reports suggests a significant involvement of the phosphoinositide (PI) cycle in cancer development and progression. Diacylglycerol kinases (DGKs) are very active in the PI cycle. They are a family of ten members that convert diacylglycerol (DAG) into phosphatidic acid (PA), two-second messengers with versatile cellular functions. Notably, some DGK isoforms, such as DGKα, have been reported to possess promising therapeutic potential in cancer therapy. However, further studies are needed in order to better comprehend their involvement in cancer. In this review, we highlight that DGKs are an essential component of the PI cycle that localize within several subcellular compartments, including the nucleus and plasma membrane, together with their PI substrates and that they are involved in mediating major cancer cell mechanisms such as growth and metastasis. DGKs control cancer cell survival, proliferation, and angiogenesis by regulating Akt/mTOR and MAPK/ERK pathways. In addition, some DGKs control cancer cell migration by regulating the activities of the Rho GTPases Rac1 and RhoA.

Description: Abstract 1289 Introduction. Azacitidine (AZA) is a DNA methyltransferase inhibitor currently approved for the treatment of high-risk MDS patients, which has been demonstrated to be feasible and effective also in low-risk MDS (Fenaux P et al, Lancet Oncol 2009; Musto P et al, Cancer 2010). However, at least 4 or 6 cycles of therapy are required for assessing the hematologic response, and predictive markers of responsiveness are still lacking. PI-PLCbeta1 plays a role in the MDS progression to AML and is a specific target for AZA therapy (Follo MY et al, PNAS 2009). Indeed, PI-PLCbeta1 has been demonstrated to be a dynamic marker for responsiveness to demethylating therapy, in that PI-PLCbeta1 mRNA increase or decrease could be associated with favourable response or failure, respectively. Stemming from these data, in this study we further investigated the role of PI-PLCbeta1 in MDS patients during AZA therapy. Methods. The study included 60 patients, 22 low-risk MDS (WHO: RA, RARS, RCMD, RAEB-1, and IPSS risk Low or Int-1), and 38 high-risk MDS (WHO: RCMD, RAEB-1, RAEB-2, and IPSS risk Int-1 or High). All the patients received a minimum of 6 cycles, in the absence of disease progression or unacceptable toxicity. Hematologic response was defined according to the revised IWG criteria (Cheson et al, Blood 2006). Positive clinical responses were defined as: Complete Remission (CR), Partial Remission (PR) or Hematologic Improvement (HI). At a molecular level, for each patient we quantified the amount of PI-PLCbeta1 mRNA at baseline and before each cycle of AZA therapy. PI-PLCbeta1 ratio was calculated as the mean expression of PI-PLCbeta1 at cycles 1 to 3, as compared with the baseline level within the same subject. In case the mean value of PI-PLCbeta1 gene expression during the cycles 1 to 3 was above the baseline level, we defined it as a “PI-PLCbeta1 early increase”. On the contrary, a “stable PI-PLCbeta1” expression was observed when subjects did not show any increase during the first three cycles of therapy, as compared with baseline. Results. Patients' median age was 69 years (range 37–85) and the median follow-up was 23 months (range 1–103). The median number of AZA cycles was 11 (range 3–59) for high-risk MDS, and 8 (range 1–8) for low-risk MDS. Positive clinical responses were observed in 37/60 (62%) of the MDS patients (7 CR, 1 PR, 29 HI). In particular, 13/22 (59%) of our low-risk MDS and 24/38 (63%) of our high-risk MDS patients showed a positive clinical response to AZA, with 4 CR, 1 PR, and 19 HI in high-risk MDS, and 3 CR and 10 HI in low-risk MDS. Overall survival (OS), Progression-Free Survival (PFS), and Overall Response Rate (ORR) were analyzed using a Kaplan-Meier method, considering p-values

Description: Phosphoinositide-specific phospholipase C (PI-PLC) gamma1 is involved in erythroid differentiation, via activation of the Akt/PI-PLCgamma1 pathway, and its increase has been associated with erythropoiesis in MDS cells. On the other hand, PI-PLCbeta1 is a nuclear inositide-dependent enzyme implicated in the regulation of hematopoietic differentiation. Interestingly, PI-PLCbeta1 increase plays an important predictive role in the response of MDS cells to epigenetic therapy. Indeed, PI-PLCbeta1 promoter is specifically hypomethylated by azacitidine, a demethylating agent that is clinically used in MDS to improve patients' overall survival and delay the AML evolution. Moreover, azacitidine is currently studied in combination with lenalidomide, to sustain both myeloid and erythroid lineages and balance MDS cell proliferation and differentiation. However, the molecular effects of this combination therapy on inositide signalling pathways and microRNA expression are still unclear. This study included 44 patients diagnosed with high-risk MDS who were given azacitidine and lenalidomide. Patients were considered clinically evaluable after at least 6 cycles of treatment. Molecular analyses were performed at baseline and during the therapy. At first, Real-Time PCR and immunocytochemical experiments were performed to determine PI-PLCbeta1 and PI-PLCgamma1 expression. Then, we also carried out cell cycle analyses and studied both PI-PLCbeta1 methylation status and the expression of erythroid-specific molecules, i.e. Globin genes. On the other hand, to further investigate the effect of the combination therapy on epigenetic mechanisms, we analyzed microRNA expression at baseline and during the treatment. In particular, we started by comparing the 4th cycle of the therapy to baseline, and in case of significant differences, for responder patients, we carried out microRNA profiling at the 8th cycle of the therapy or during the follow-up. Our study included 44 patients, but only 28 subjects were clinically evaluable, with an overall response rate of 78.6% (22/28 cases). At a molecular level, a significant increase of PI-PLCbeta1 expression was associated with a favourable clinical response to the combination therapy. Moreover, responder cases also showed an increased expression of Beta-Globin and PI-PLCgamma1, hinting at a specific contribution of lenalidomide on erythroid activation. On the other hand, the frequent demethylation of PI-PLCbeta1 promoter in responder cases could be specifically linked to azacitidine. Furthermore, MDS cells treated with azacitidine and lenalidomide not only showed an increased G0/G1 phase of cell cycle, but also microRNA expression was affected. In fact, responder and non responder cases showed a specific molecular pattern of microRNAs and, interestingly, some of these microRNAs can target or are strictly associated with inositide signalling pathways. Our results show that the combination of azacitidine and lenalidomide in high-risk MDS patients can be important to induce PI-PLCbeta1, and possibly PI-PLCgamma1. These enzymes can regulate cell cycle, myeloid and erythroid differentiation, thus improving peripheral cytopenia. On the other hand, a specific microRNA signature is important to make a molecular distinction between responder and non responder cases, so that their expression or interactions, possibly with PI-PLCs or other nuclear inositides, can be important to disclose new mechanisms in MDS pathogenesis and identify new predictive markers for the assessment of the response to azacitidine and lenalidomide therapy. Disclosures Gobbi: Novartis: Consultancy, Research Funding; Mundipharma: Consultancy, Research Funding; Roche: Honoraria; Janssen: Consultancy, Honoraria; Gilead: Honoraria; Celgene: Consultancy; Takeda: Consultancy. Finelli:Novartis: Other: Speaker fees; Celgene: Other: Speaker fees; Celgene: Research Funding.

Description: Abstract 2384 Poster Board II-361 Introduction: Phosphoinositide-phospholipase (PI-PLC) C beta1, PI-PLCgamma1 and Akt are key enzymes in nuclear signal transduction pathways, affecting both cell cycle and differentiation in normal physiology and neoplastic transformation. Our group previously showed not only that the Akt/mTOR axis is activated in patients with high-risk MDS (Follo MY et al, Cancer Res 2007), but also that there is an inverse correlation between PI-PLCbeta1 expression and Akt activation (Follo MY et al, Leukemia 2008). Moreover, we recently demonstrated that patients belonging to all of the IPSS risk groups can display a PI-PLCbeta1 mono-allelic deletion, and that this cytogenetic alteration is associated with a higher risk of evolution into Acute Myeloid Leukemia (AML) (Follo MY et al, J Clin Oncol 2009). Erythropoietin (EPO) is an effective treatment of anemia in 40-60% of low-risk MDS, often inducing a prolonged response. Interestingly, the activation of the EPO receptor has been correlated to the PI3K/Akt axis, which in turn is linked to either PI-PLCbeta1 or PI-PLCgamma1 signalling, so that EPO could affect cell proliferation and apoptosis. The aim of this study was therefore to clarify the relationship between EPO treatment and lipid signalling pathways, to investigate their role as molecular targets or predictive factors during EPO therapy. In fact, in patients who are refractory or lose response to EPO there could be a specific activation or inhibition of pathways involved in both cell cycle and differentiation. Patients and Methods: In this study we examined the effect of EPO treatment on lipid signal transduction pathways in MDS patients. The study included 16 patients (IPSS risk: low or intermediate-1), with a favourable response to EPO in 8/16 (50%) of the cases. For each patient we had the opportunity to analyze the expression of PI-PLCbeta1, PI-PLCgamma1, p-Akt and PIP2, which is involved in both PI-PLCbeta1 and PI3K/Akt activation processes, before and during EPO treatment, in order to detect every change in both clinical and biological features. By FISH analysis, we firstly assessed the presence of PI-PLCbeta1 mono-allelic deletion. Then, we quantified PI-PLCbeta1 and PI-PLCgamma1 gene and protein expression, as well as PIP2 and the degree of Akt activation; mRNA levels were quantified by real-time PCR, whereas the protein amount was detected by both a immunocytochemical and a flow cytometric detection approach. Results: The PI-PLCbeta1 mono-allelic deletion was found in 5/16 (31%) low-risk MDS patients: 2 of them showed a rapid evolution into AML, whilst the remaining 3 cases did not respond to EPO treatment. The molecular analyses showed a specific increase in Akt/PI-PLCgamma1 pathway for responder patients, whereas most of the patients refactory to EPO displayed a slight decrease in p-Akt levels and an activation of PI-PLCbeta1 signalling during EPO administration, so that these patients seem to counteract the lack of one PI-PLCbeta1 allele by increasing PI-PLCbeta1 gene and protein expression. Conclusions: Our results, although obtained in a small number of cases, confirm the possible involvement of PI-PLCbeta1 pathways in the EPO signalling. Moreover, our data suggest that the presence of the PI-PLCbeta1 mono-allelic deletion is associated with a worse clinical outcome and with a lack of response to EPO treatment, even in low-risk MDS patients who apparently have a good response profile for EPO (recent diagnosis, absence of long-term transfusion dependence, low or intermediate-1 IPSS risk, serum EPO levels