Repairing of N-mustard derivative BO-1055 induced DNA damage requires NER, HR, and MGMT-dependent DNA repair mechanisms

Diarylureas as Antitumor Agents

The diarylurea is a scaffold of great importance in medicinal chemistry as it is present in numerous heterocyclic compounds with antithrombotic, antimalarial, antibacterial, and anti-inflammatory properties. Some diarylureas, serine-threonine kinase or tyrosine kinase inhibitors, were recently reported in literature. The first to come into the market as an anticancer agent was sorafenib, followed by some others. In this review, we survey progress over the past 10 years in the development of new diarylureas as anticancer agents.

Probing the characteristics and biofunctional effects of disease-affected cells and drug response via machine learning applications

Drug-induced transformations in disease characteristics at the cellular and molecular level offers the opportunity to predict and evaluate the efficacy of pharmaceutical ingredients whilst enabling the optimal design of new and improved drugs with enhanced pharmacokinetics and pharmacodynamics. Machine learning is a promising in-silico tool used to simulate cells with specific disease properties and to determine their response toward drug uptake. Differences in the properties of normal and infected cells, including biophysical, biochemical and physiological characteristics, plays a key role in developing fundamental cellular probing platforms for machine learning applications. Cellular features can be extracted periodically from both the drug treated, infected, and normal cells via image segmentations in order to probe dynamic differences in cell behavior. Cellular segmentation can be evaluated to reflect the levels of drug effect on a distinct cell or group of cells via probability scoring. This article provides an account for the use of machine learning methods to probe differences in the biophysical, biochemical and physiological characteristics of infected cells in response to pharmacokinetics uptake of drug ingredients for application in cancer, diabetes and neurodegenerative disease therapies.

Increased Non-Homologous End Joining Makes DNA-PK a Promising Target for Therapeutic Intervention in Uveal Melanoma

Uveal melanoma (UM) is the most common primary intraocular tumour in adults, with a mean survival of six months following metastasis. The survival rates have not improved in over 30 years. This study has shown that sister chromatid exchange (SCE) is low in UM which is likely due to a reduced expression of FANCD2. As FANCD2 can function to suppress non-homologous end joining (NHEJ), this study therefore investigated NHEJ in UM. The activation of the catalytic subunit of the NHEJ pathway protein DNA-dependent protein kinase (DNA-PK) was measured by analysing the foci formation and the ligation efficiency by NHEJ determined using a plasmid-based end-joining assay. Using small-interfering RNA (siRNA) knock-down, and chemical inhibitors of DNA-PK, the survival of primary UM cultures and two cell lines were determined. To assess the homologous recombination capacity in response to the inhibition of DNA-PK, a SCE analysis was performed. In addition, to support the findings, the messenger RNA (mRNA) expression of genes associated with NHEJ was analysed using the Cancer Genome Atlas (TCGA)-UM RNAseq data (n = 79). The NHEJ activity and DNA-PKcs activation was upregulated in UM and the inhibition of DNA-PK selectively induced apoptosis and sensitized to ionising radiation and inter-strand cross-linking agents. The inhibition of the NHEJ protein DNA-PK is lethal to UM, indicating a potentially effective therapeutic option, either alone or as a sensitizer for other treatments.

MGMT methylation correlates with melphalan pelvic perfusion survival in stage III melanoma patients: a pilot study

Approximately 25% of melanoma patients with locoregional metastases are nonresponsive to new molecular target therapy and immunotherapy. When metastases are located in the pelvis, melphalan hypoxic perfusion can be an optional treatment. Because methylation of MGMT promoter increases the efficacy of alkylating agents, studies on melanoma outcome of patients treated with melphalan regional chemotherapy should consider this epigenetic change. This study aims to evaluate whether the survival of stage III melanoma patients treated with melphalan regional chemotherapy may be correlated with MGMT methylation status. The metastatic tissues of 27 stage III melanoma patients with locoregional metastases located in the pelvis subjected to melphalan hypoxic pelvic perfusion were examined. The methylation status of the MGMT promoter was investigated by MS-MLPA probes analysis and the presence of the BRAF V600E mutation was analyzed by CAST-PCR. The median survival times were estimated using the Kaplan–Meier curves and were stratified according to the clinicopathological characteristics of patients and lesions. The overall median survival time was 17 months. The 1-year, 3-year, and 5-year survival rates were 66.7, 18.5, and 7.4%, respectively. Disease stage, burden, and percentage of MGMT methylation significantly affected survival. We estimated an MGMT promoter methylation cut-off of at least 14%, which was significantly associated with a longer survival after melphalan regional chemotherapy. Our data suggest that MGMT promoter methylation could be an important factor in determining which melanoma patients should receive melphalan regional chemotherapy, but its prognostic significance in the routine clinical setting needs to be clarified in a larger study.

BO-1055, a novel DNA cross-linking agent with remarkable low myelotoxicity shows potent activity in sarcoma models

DNA damaging agents cause rapid shrinkage of tumors and form the basis of chemotherapy for sarcomas despite significant toxicities. Drugs having superior efficacy and wider therapeutic windows are needed to improve patient outcomes. We used cell proliferation and apoptosis assays in sarcoma cell lines and benign cells; γ-H2AX expression, comet assay, immunoblot analyses and drug combination studies in vitro and in patient derived xenograft (PDX) models. BO-1055 caused apoptosis and cell death in a concentration and time dependent manner in sarcoma cell lines. BO-1055 had potent activity (submicromolar IC50) against Ewing sarcoma and rhabdomyosarcoma, intermediate activity in DSRCT (IC50 = 2-3μM) and very weak activity in osteosarcoma (IC50 >10μM) cell lines. BO-1055 exhibited a wide therapeutic window compared to other DNA damaging drugs. BO-1055 induced more DNA double strand breaks and γH2AX expression in cancer cells compared to benign cells. BO-1055 showed inhibition of tumor growth in A673 xenografts and caused tumor regression in cyclophosphamide resistant patient-derived Ewing sarcoma xenografts and A204 xenografts. Combination of BO-1055 and irinotecan demonstrated synergism in Ewing sarcoma PDX models. Potent activity on sarcoma cells and its relative lack of toxicity presents a strong rationale for further development of BO-1055 as a therapeutic agent.

Interstrand Crosslink Repair as a Target for HDAC Inhibition

DNA interstrand crosslinks (ICLs) covalently connect complementary DNA strands. Consequently, DNA replication and transcription are hampered, DNA damage responses (DDR) are initiated, and cell death is triggered. Therefore, drugs inducing ICLs are effective against rapidly growing cancer cells. However, tumors engage a complicated enzymatic machinery to repair and survive ICLs. Several factors, including the post-translational acetylation/deacetylation of lysine residues within proteins, control this network. Histone deacetylases (HDACs) modulate the expression and functions of DNA repair proteins which remove ICLs and control the accessibility of chromatin. Accordingly, histone deacetylase inhibitors (HDACi) are small, pharmacologically and clinically relevant molecules that sensitize cancer cells to ICL inducers. We discuss the mechanism of ICL repair and targets of HDACi within this pathway.