Panobinostat (LBH589) increase survival in adult xenografic model of acute lymphoblastic leukemia with t(4;11) but promotes antagonistic effects in combination with MTX and 6MP.

Patients diagnosed with acute lymphoblastic leukemia (ALL) bearing t(4;11)/MLL-AF4 have aggressive clinical features, poor prognosis and there is an urgent need for new therapies to improve outcomes. Panobinostat (LBH589) has been identified as a potential therapeutic agent for ALL with t(4;11) and studies suggest that the antineoplastic effects are associated with reduced MLL-AF4 fusion protein and reduced expression of HOX genes. Here, we evaluated the in vitro effects of the combination of LBH589 with methotrexate (MTX) or 6-mercaptopurine (6MP) by cell proliferation assays and Calcusyn software in ALL cell line (RS4;11); the in vivo effects of LBH589 in xenotransplanted NOD-scid IL2Rgammanull mice measuring human lymphoblasts by flow cytometry; and the expression of HOX genes by qPCR after treatment in an adult model of ALL with t(4;11). LBH589 combination with MTX or 6MP did not promote synergistic effects in RS4;11 cell line. LBH589 treatment leads to increased overall survival and reduction of blasts in xenotransplanted mice but caused no significant changes in HOXA7, HOXA9, HOXA10, and MEIS1 expression. The LBH589, alone, showed promising antineoplastic effects in vivo and may represent a potential agent for chemotherapy in ALL patients with t(4;11).

Repression of HIV-1 reactivation mediated by CRISPR/dCas9-KRAB in lymphoid and myeloid cell models.

BACKGROUND: Despite antiretroviral treatment efficacy, it does not lead to the complete eradication of HIV infection. Consequently, reactivation of the virus from latently infected cell reservoirs is a major challenge toward cure efforts. Two strategies targeting viral latency are currently under investigation: the "shock and kill" and the "block and lock." The "Block and Lock" methodology aims to control HIV-1 latency reactivation, promoting a functional cure. We utilized the CRISPR/dCas9-KRAB platform, which was initially developed to suppress cellular genes transcription, to block drug-induced HIV-1 reactivation in latently infected T cells and myeloid cells. RESULTS: We identified a set of five sgRNAs targeting the HIV-1 proviral genome (LTR1-LTR5), having the lowest nominated off-target activity, and transduced them into the latently infected lymphoid (J-Lat 10.6) and myeloid (U1) cell lines. One of the sgRNAs (LTR5), which binds specifically in the HIV-1 LTR NFκB binding site, was able to promote robust repression of HIV-1 reactivation in latently infected T cells stimulated with Phorbol 12-Myristate 13-Acetate (PMA) and Ingenol B (IngB), both potent protein kinase C (PKC) stimulators. Reactivation with HDAC inhibitors, such as SAHA and Panobinostat, showed the same strong inhibition of reactivation. Additionally, we observed a hundred times reduction of HIV-1 RNA expression levels in the latently infected myeloid cell line, U1 induced with IngB. CONCLUSION: Taken together, our results show that the KRAB fused CRISPR/dCas9 system can robustly prevent the HIV-1 latency reactivation process, mediated by PMA or IngB and SAHA or Panobinostat, both in myeloid and lymphoid HIV-1 latently infected cells. In addition, we demonstrated that KRAB repressor protein is crucial to reactivation resistance phenotype, and we have identified some useful hotspots sequences in HIV-1 LTR for the design sgRNAs.

Effects of cisplatin and panobinostat on human mesothelial (Met-5A) and malignant pleural mesothelioma (MSTO-211H) cells.

New therapeutic approaches are still needed for effective malignant pleural mesothelioma treatment. The use of classical chemotherapy agents in combination with newly developed molecules may shed light on new therapeutic approaches. We aimed to determine the efficacy of panobinostat, alone and in combination with cisplatin, on cell survival and mRNA expression of FOXO3A, CCND1, and CASP9 genes in both mesothelioma and healthy mesothelial cell lines. Cells were treated with 1-100 µM cisplatin and 25-1000 nM panobinostat. Methylthiazol tetrazolium assays were performed to determine cell viability. mRNA expression levels of genes were analyzed with quantitative real-time polymerase chain reaction. Cisplatin and panobinostat exposure of the cells for 24 h resulted in decreased cell survival. The combined treatment was found to be more effective. No significant changes were observed with respect to CCND1 expression after exposure to agents alone or in combination. However, agents in combination resulted in upregulation of FOXO3A and CASP9 in MSTO-211H cells. Gene expression levels were not affected by any agents in healthy cells. Use of cisplatin in combination with new chemotherapeutic agents may reduce the toxic effects of cisplatin in normal cells and result in more effective removal of tumor cells.