A pyridinium‑type fullerene derivative suppresses primary effusion lymphoma cell viability via the downregulation of the Wnt signaling pathway through the destabilization of β‑catenin

Macrophage-Mediated Delivery of miR-34a-5p-Nanoparticles for Pathogenic Inhibition of Kaposi's Sarcoma-Associated Herpesvirus

Kaposi's sarcoma-associated herpesvirus (KSHV) has been demonstrated to trigger a variety of malignant neoplasms, however, there are currently no targeted pharmaceutical interventions available. MicroRNA(miRNA)-based antiviral and tumor therapies are frequently utilized, yet the challenges of cellular uptake and susceptibility to degradation underscore the necessity for a delivery system that can effectively combat KSHV. Nonetheless, despite the efficacy of nanocarriers in delivering drugs into cells, they continue to encounter challenges in penetrating the brain. In this study, a macrophage inflammation model was developed to enhance the delivery of miR-34a-5p loaded by folic acid-modified β-cyclodextrin grafted polyethyleneimine (β-CD-PEI-FA) nanocomposites, based on FA targeted to folate receptors on the surface of macrophages and tumor cells. Both in vivo and in vitro safety evaluations of the nanocarriers were performed, which confirmed the exceptional biocompatibility. Assays involving the coculture of induced nanodrug-loaded macrophages and KSHV-positive cells demonstrated the efficient delivery of miR-34a-5p into KSHV-positive cells through macrophages. This delivery led to the inhibition of the proliferation and cell cycle of cocultured KSHV-positive cells, as well as a significant reduction in the expression of KSHV pathogenic genes RTA and v-GPCR. Notably, fluorescence imaging of organs revealed the in vivo delivery of nanocomposites into brain tissues, including tumors. Furthermore, immunohistochemistry analysis revealed increased macrophages infiltration in both tumors and brain tissues in xenograft mice. In conclusion, our study presents a pioneering strategy employing macrophages as carriers for delivering β-CD-PEI-FA/miR-34a-5p nanocomplexes in anti-KSHV therapy.

Kaposi's Sarcoma-Associated Herpesvirus ORF21 Enhances the Phosphorylation of MEK and the Infectivity of Progeny Virus

Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus-8, is the causative agent of Kaposi's sarcoma, Castleman's disease, and primary effusion lymphoma. Although the functions of the viral thymidine kinases (vTK) of herpes simplex virus-1/2 are well understood, that of KSHV ORF21 (an ortholog of vTK) is largely unknown. Here, we investigated the role of ORF21 in lytic replication and infection by generating two ORF21-mutated KSHV BAC clones: ORF21-kinase activity deficient KSHV (21KD) and stop codon-induced ORF21-deleted KSHV (21del). The results showed that both ORF21 mutations did not affect viral genome replication, lytic gene transcription, or the production of viral genome-encapsidated particles. The ORF21 molecule-dependent function, other than the kinase function of ORF21, was involved in the infectivity of the progeny virus. ORF21 was expressed 36 h after the induction of lytic replication, and endogenously expressed ORF21 was localized in the whole cytoplasm. Moreover, ORF21 upregulated the MEK phosphorylation and anchorage-independent cell growth. The inhibition of MEK signaling by U0126 in recipient target cells suppressed the number of progeny virus-infected cells. These suggest that ORF21 transmitted as a tegument protein in the progeny virus enhances the new infection through MEK up-regulation in the recipient cell. Our findings indicate that ORF21 plays key roles in the infection of KSHV through the manipulation of the cellular function.

Targeting c-Myc Unbalances UPR towards Cell Death and Impairs DDR in Lymphoma and Multiple Myeloma Cells

Multiple myeloma (MM) and primary effusion lymphoma (PEL) are aggressive hematological cancers, for which the search for new and more effective therapies is needed. Both cancers overexpress c-Myc and are highly dependent on this proto-oncogene for their survival. Although c-Myc inhibition has been shown to reduce PEL and MM survival, the underlying mechanisms leading to such an effect are not completely clarified. In this study, by pharmacologic inhibition and silencing, we show that c-Myc stands at the cross-road between UPR and DDR. Indeed, it plays a key role in maintaining the pro-survival function of UPR, through the IRE1α/XBP1 axis, and sustains the expression level of DDR molecules such as RAD51 and BRCA1 in MM and PEL cells. Moreover, we found that c-Myc establishes an interplay with the IRE1α/XBP1 axis whose inhibition downregulated c-Myc, skewed UPR towards cell death and enhanced DNA damage. In conclusion, this study unveils new insights into the molecular mechanisms leading to the cytotoxic effects of c-Myc inhibition and reinforces the idea that its targeting may be a promising therapeutic approach against MM and PEL that, although different cancers, share some similarities, including c-Myc overexpression, constitutive ER stress and poor response to current chemotherapies.