Search

Background: We previously established a patient‐derived xenograft (PDX) model, patient‐derived organoids (PDOs), and PDX‐derived organoids (PDXOs) for salivary duct carcinoma (SDC). Using these models, this study examined the therapeutic effect of human epidermal growth factor receptor 2 (HER2) blockade on HER2‐positive SDC. Methods: The therapeutic effect of lapatinib was assessed in SDC PDXOs with regards to cell growth, receptor/downstream signaling molecule expression, phosphorylation levels, and apoptosis. Effect of lapatinib treatment was evaluated in vivo in SDC PDX mice. Results: The siRNA knockdown of HER2 and lapatinib suppressed cell proliferation in SDC PDXOs. Lapatinib inhibited the phosphorylation of HER2 and its downstream targets, and induced apoptosis in SDC PDXOs. Lapatinib also significantly reduced tumor volumes compared with that of the control in SDC PDX mice. Conclusion: For the first time, we demonstrated the efficacy of anti‐HER2 therapy in HER2‐positive SDC using preclinical models of SDC PDX and PDXO. [ABSTRACT FROM AUTHOR]

To generate a reliable preclinical model system exhibiting the molecular features of salivary adenoid cystic carcinoma (ACC) whose biology is still unclear due to the paucity of stable cell cultures. To develop new in vitro and in vivo models of ACC, the techniques of organoid culture and patient‐derived tumor xenograft (PDX), which have attracted attention in other malignancies in recent years, were applied. Tumor specimens from surgically resected salivary ACC were proceeded for the preparation of PDX and organoid culture. The orthotopic transplantation of patient‐derived or PDX‐derived organoids was demonstrated into submandibular glands of NSG mice and those histology was evaluated. PDX‐derived organoid cells were evaluated for the presence of MYB‐mediated fusion genes and proceeded for in vitro drug sensitivity assay. Human ACC‐derived organoids were successfully generated in three‐dimensional culture and confirmed the ability of these cells to form tumors by orthotopic injection. Short‐term organoid cell cultures from two individual ACC PDX tumors were also established that maintain the characteristic MYBL1 translocation and histological features of the original parent and PDX tumors. Finally, the establishment of drug sensitivity tests on these short‐term cultured cells was confirmed using three different agents. This is the first to report an approach for the generation of human ACC‐derived organoids as in vitro and in vivo cancer models, providing insights into understanding of the ACC biology and creating personalized therapy design for patients with ACC. What's new? The biological underpinnings of salivary adenoid cystic carcinoma (ACC) remain largely unknown, owing to a lack of preclinical model systems. In this study, the authors describe the successful generation of human salivary ACC cell lines from organoid culture and the subsequent development of an in vivo salivary ACC mouse model. The orthotopic xenograft mouse model was established efficiently from ACC organoid cells from patient‐derived xenografts (PDX). Short‐term cultures of PDX‐derived ACC organoid cells further were amenable for in vitro drug‐sensitive studies with several agents. This novel approach could be useful for investigating personalized therapies for patients with salivary ACC. [ABSTRACT FROM AUTHOR]

Abstract: The cathepsin B inhibitor surugamide B (2), along with structurally related derivatives (A and C–E), has previously been isolated from the marine actinomycete Streptomyces sp. JAMM992. The biosynthetic genes are unexpectedly part of a cluster of four non‐ribosomal peptide synthetase (NRPS) genes, two of which are responsible for the biosynthesis of the additional linear decapeptide surugamide F. However, the thioesterase domain required for the later stage of the biosynthesis of the cyclic peptides surugamides A–E is not present in any module architecture of the surugamide NRPSs. Herein, we report the first total synthesis of surugamide B (2) through the macrocyclization at the biomimetic position, which not only alleviated the Cα epimerization in the macrolactamization process, but also efficiently provided 2 in 34 % yield for 18 steps. Furthermore, both the chemical and enzymatic studies with the biosynthetic precursor mimics revealed that the stand‐alone enzyme SurE, which belongs to the penicillin‐binding protein family, is responsible for macrocyclization of the tethered octapeptidyl intermediate. [ABSTRACT FROM AUTHOR]

Recent studies showed that human papillomavirus (HPV) integration contributes to the genomic instability seen in HPV-associated head and neck squamous cell carcinoma (HPV-HNSCC). However, the epigenetic alterations induced after HPV integration remains unclear. To identify the molecular details of HPV16 DNA integration and the ensuing patterns of methylation in HNSCC, we performed next-generation sequencing using a target-enrichment method for the effective identification of HPV16 integration breakpoints as well as the characterization of genomic sequences adjacent to HPV16 integration breakpoints with three HPV16-related HNSCC cell lines. The DNA methylation levels of the integrated HPV16 genome and that of the adjacent human genome were also analyzed by bisulfite pyrosequencing. We found various integration loci, including novel integration sites. Integration loci were located predominantly in the intergenic region, with a significant enrichment of the microhomologous sequences between the human and HPV16 genomes at the integration breakpoints. Furthermore, various levels of methylation within both the human genome and the integrated HPV genome at the integration breakpoints in each integrant were observed. Allele-specific methylation analysis suggested that the HPV16 integrants remained hypomethylated when the flanking host genome was hypomethylated. After integration into highly methylated human genome regions, however, the HPV16 DNA became methylated. In conclusion, we found novel integration sites and methylation patterns in HPV-HNSCC using our unique method. These findings may provide insights into understanding of viral integration mechanism and virus-associated carcinogenesis of HPV-HNSCC. [ABSTRACT FROM AUTHOR]

Development of modulators of constitutively active, kinase domain mutants of c-Kit has proved to be very difficult. Therefore, a high-throughput differential cytotoxicity assay was developed to screen for compounds that preferentially kill cells expressing constitutively active c-Kit. The cells used in the assay, murine IC2 mast cells, express either the D814Y activating mutation (functionally equivalent to human D816Y) or wild type protein. This assay is robust and highly reproducible. When applied to libraries of natural product extracts (followed by assay-guided fractionation), two differentially active compounds were identified. To assess possible mechanisms of action, the active compounds were tested for inhibitory activity against a panel of signaling enzymes (including wild type and mutant c-Kit). Neither of the compounds significantly affected any of the 73 enzymes tested. The effects of commercially available modulators of known signaling components were also assessed using the screening assay. None of these inhibitors reproduced the differential activity seen with the natural products. Finally, both compounds were found to affect mitochondrial potential in cells expressing c-KitD814Y. These results suggest that the newly identified natural products may provide new avenues for intervention in aberrant c-Kit signaling pathways. [ABSTRACT FROM AUTHOR]

Bioassay-guided fractionation of the extract of the rare deep-sea marine sponge Pleroma sp. [ABSTRACT FROM AUTHOR]

Two pyridoacridines, N-hydroxymethylisocystodamine (I) and neolabuanine A (II) together with six known compounds are isolated from the title sponge. [ABSTRACT FROM AUTHOR]