Analysis of miR-483-3p and miR-630 expression profile in pediatric adrenocortical tumors and the effect of their modulation on adrenal tumorigenesis in vitro.

Pediatric adrenocortical tumors (ACT) are rare aggressive neoplasms with heterogeneous prognosis. MicroRNA (miRNA) signatures have been associated with cancer diagnosis, treatment response, and outcomes of several types of cancer. However, the role played by miRNAs in pediatric ACT has been poorly explored. In this study, we have evaluated the expression of miR-483-3p and miR-630 in 67 pediatric ACT and 19 non-neoplastic adrenal samples, the effects of the modulations of these miRNAs, and their relationship with the TGF-ß pathway in the H295R and H295A cell lines. Deregulation of both miRNAs was related to survival and disease advanced stages and hence to patients' prognosis. Moreover, modified miR-483-3p and miR-630 in vitro expression decreased cell viability and colony formation capacity, changed how some genes of the TGF-ß pathway, such as TGFBR1, TGFBR2, and SMAD7, are expressed, and altered Smad3, pSmad3, Smad 2/3, N-cadherin, and Vimentin protein expression. Besides that, when inhibition of the TGF-ß pathway was combined with miR-630 overexpression or miR-483-3p silencing, cell viability and colony formation capacity decreased, and protein expression in the TGF-ß pathway changed. Together, the data indicate that both miRNAs participate in the TGF-ß pathway and are therefore potential markers for predicting the prognosis of patients with pediatric ACT.

Tetra-O-methyl nordihydroguaiaretic acid, an inhibitor of Sp1-mediated survivin transcription, induces apoptosis and acts synergistically with chemo-radiotherapy in glioblastoma cells.

Glioblastoma (GBM), one of the most malignant human neoplasias, responds poorly to current treatment modalities, with temozolomide (TMZ) being the drug most frequently used for its treatment. Tetra-O-methyl Nordihydroguaiaretic Acid (M4N) is a global transcriptional repressor of genes dependent on the Sp1 transcription factor, such as Survivin and Cdk1. In the present study we evaluated the gene expression of Survivin, its spliced variants and Cdk1 in GBM samples and cell lines. Moreover, we investigated the effects of M4N combined or not with TMZ and/or radiation on GBM primary cultures and cell lines. qRT-PCR assays were performed to determine the Survivin-spliced variants and Cdk1 gene mRNA expression in GBM tumor samples and cell lines. Cell proliferation was measured by XTT assay and cell cycle and apoptosis were determined by flow cytometry. Drug combination analyses using different schedules of administration (simultaneous and sequential) were performed on GBM cell lines and primary cultures based on the Chou-Talalay method. For clonogenic survival, doses of 2, 4, and 6 Gy of gamma radiation. were used. All Survivin-spliced variants and the Cdk1 gene were expressed in GBM samples (n = 16) and cell lines (n = 6), except the Survivin-2B variant that was only expressed in GBM cell lines. M4N treatment down regulated the expression of Cdk1, Survivin and the Survivin-ΔEx3 variant, while the Survivin-2B variant was up-regulated. M4N decreased the cell proliferation separately and synergistically with TMZ, and enhanced the effects of radiation, mainly when associated with TMZ. M4N also induced apoptotic cell death, decreased the mitotic index and arrested the cell cycle mainly in the G2/M phase. Our results suggest a potential clinical application of M4N in combination with TMZ and radiation for GB treatment.

Inhibition of nuclear factor-κB by dehydroxymethylepoxyquinomicin induces schedule-dependent chemosensitivity to anticancer drugs and enhances chemoinduced apoptosis in osteosarcoma cells.

Osteosarcoma (OS) is the most common primary malignant bone tumor, usually developing in children and adolescents, and is highly invasive and metastatic, potentially developing chemoresistance. Thus, novel effective treatment regimens are urgently needed. This study was the first to investigate the anticancer effects of dehydroxymethylepoxyquinomicin (DHMEQ), a highly specific nuclear factor-κB (NF-κB) inhibitor, on the OS cell lines HOS and MG-63. We demonstrate that NF-κB blockade by DHMEQ inhibits proliferation, decreases the mitotic index, and triggers apoptosis of OS cells. We examined the effects of combination treatment with DHMEQ and cisplatin, doxorubicin, or methotrexate, drugs commonly used in OS treatment. Using the median effect method of Chou and Talalay, we evaluated the combination indices for simultaneous and sequential treatment schedules. In all cases, combination with a chemotherapeutic drug produced a synergistic effect, even at low single-agent cytotoxic levels. When cells were treated with DHMEQ and cisplatin, a more synergistic effect was obtained using simultaneous treatment. For the doxorubicin and methotrexate combination, a more synergistic effect was achieved with sequential treatment using DHMEQ before chemotherapy. These synergistic effects were accompanied by enhancement of chemoinduced apoptosis. Interestingly, the highest apoptotic effect was reached with sequential exposure in both cell lines, independent of the chemotherapeutic agent used. Likewise, DHMEQ decreased cell invasion and migration, crucial steps for tumor progression. Our data suggest that combining DHMEQ with chemotherapeutic drugs might be useful for planning new therapeutic strategies for OS treatment, mainly in resistant and metastatic cases.