Background & Aims Fibrolamellar carcinoma (FLC) is a rare liver cancer that primarily affects adolescents and young adults. It is characterized by a heterozygous approximately 400-kb deletion on chromosome 19 that results in a unique fusion between DnaJ heat shock protein family member B1 (DNAJB1) and the alpha catalytic subunit of protein kinase A (PRKACA). The role of microRNAs (miRNAs) in FLC remains unclear. We identified dysregulated miRNAs in FLC and investigated whether dysregulation of 1 key miRNA contributes to FLC pathogenesis. Methods We analyzed small RNA sequencing (smRNA-seq) data from The Cancer Genome Atlas to identify dysregulated miRNAs in primary FLC tumors and validated the findings in 3 independent FLC cohorts. smRNA-seq also was performed on a FLC patient-derived xenograft model as well as purified cell populations of the liver to determine whether key miRNA changes were tumor cell–intrinsic. We then used clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (Cas9) technology and transposon-mediated gene transfer in mice to determine if the presence of DNAJB1-PRKACA is sufficient to suppress miR-375 expression. Finally, we established a new FLC cell line and performed colony formation and scratch wound assays to determine the functional consequences of miR-375 overexpression. Results We identified miR-375 as the most dysregulated miRNA in primary FLC tumors (27-fold down-regulation; P = .009). miR-375 expression also was decreased significantly in a FLC patient-derived xenograft model compared to 4 different cell populations of the liver. Introduction of DNAJB1-PRKACA by clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 engineering and transposon-mediated somatic gene transfer in mice was sufficient to induce significant loss of miR-375 expression ( P < .05). Overexpression of miR-375 in FLC cells inhibited Hippo signaling pathway proteins, including yes-associated protein 1 and connective tissue growth factor, and suppressed cell proliferation and migration ( P < .05). Conclusions We identified miR-375 as the most down-regulated miRNA in FLC tumors and showed that overexpression of miR-375 mitigated tumor cell growth and invasive potential. These findings open a potentially new molecular therapeutic approach. Further studies are necessary to determine how DNAJB1-PRKACA suppresses miR-375 expression and whether miR-375 has additional important targets in this tumor. Transcript profiling: GEO accession numbers: GSE114974 and GSE125602.

Key indicators: single-crystal X-ray study; T = 295 K; mean (C-C) = 0.002 Å; R factor = 0.033; wR factor = 0.097; data-to-parameter ratio = 14.0.The asymmetric unit of the title complex, [Co(C 5

Kaposi's sarcoma‐associated herpesvirus (KSHV) is a human gammaherpesvirus that is associated with the development of Kaposi's sarcoma and primary effusion lymphoma. KSHV establishes two alternate genetic life cycle programs upon infection of its host cells, which maintain a latent infection in infected cells but undergo lytic reactivation in response to various stimuli. In this study, we used BCBL‐1, persistent KSHV‐infected B lymphoma cell line, where the lytic and latent cycle of KSHV was regulated by TPA treatment. Alloferon is an immunomodulating peptide originating from insects which has been successfully developed in clinical trials as antiviral drug in Russia and showed remarkable effect on prevention of recurrent HSV infection. However, its specific mechanism remains to be clarified. We investigated the effect of alloferon on the regulation of lytic reactivation in viral infected cells. We found that alloferon effectively suppressed the down‐regulation of cell proliferation induced by TPA treatment. It suggests that the lytic reactivation of KSHV within BCBL‐1 can be regulated by alloferon. We next investigated the specific intracellular target of alloferon. Alloferon regulated the expression level of RTA as lytic switch protein, and that of ORF45 and vIRF2, which inhibit the production of type I IFNs. Therefore, we suggests that alloferon may be an effective antiviral agent on KSHV infection.

CM1 (centrocyte/‐blast marker 1) is originally defined as a germinal center (GC) B cell marker and it plays a critical role on B cell development in GC. In addition, CM1 is expressed on Burkitt's lymphoma cell lines. It suggests that CM1 plays a role in the pathogenesis of tumor cells. Cyclooxygenase‐2 (COX‐2) and its product, prostaglandin E2 (PGE2) are well‐known molecules, which are closely related with the pathogenesis of several kinds of tumor. Therefore, we investigated the role of CM1 on the regulation of COX‐2 expression and PGE2 production from Burkitt's lymphoma cell lines, such as Raji and Ramos. When CM1 was ligated with anti CM1 mAb, PGE2 production was increased and CM1‐induced PGE2 production was inhibited by the pre‐treatment of NS‐398, COX‐2 specific inhibitor and kamebakaurin, specific inhibitor of NF‐kB. Finally, the effect of increased PGE2 production by CM1 ligation on activation induced cytidine deaminase (AID) was evaluated. The expression of AID was increased by CM1 ligation and it was suppressed by the pre‐treatment of NS‐398 and kamebakaurin. Taken together, CM1‐induced PGE2 production increases the expression of AID via the activation of NF‐kB and increase of enzymatic activity of COX‐2.

UVB irradiation modulates immune responses and activates inflammatory reactions, leading to skin damage like sunburn. Alloferon is isolated from the blood of an experimentally infected insect, the blow fly Calliphora vicina (Diptera), and shows a variety of biomedical efficacies such as antiviral and antitumoral capabilities. However, the specific molecular mechanisms for the action of alloferon still remain to be clarified. In this study, we investigated the effects of alloferon on cutaneous inflammation induced by UVB‐irradiation in human HaCaT keratinocytes. RPA and ELISA data showed alleferon decreased the production of UVB‐induced pro‐inflammatory cytokine, such as IL‐1α, IL‐1β, IL‐6, IL‐18, both on the mRNA and protein level. Western blot analysis showed alleferon inhibited the activation of p38 MAPK induced by UVB irradiation. Furthermore, the topical application of alloferon on hairless mouse skin exposed to UVB has shown that post‐treatment of alloferon significantly reduced the thickness of epidermal layer of chronically UVB exposed mice skin. In addition, alloferon inhibited increased production of the IL‐6 in hairless mice skin. These findings suggest that alleferon has significant anti‐inflammatory effects on the UVB‐induced response on the cutaneous inflammation and may offer an effective approach to reduction or prevention of skin inflammation resulting from UVB irradiation.