Small-molecule exhibits anti-tumor activity by targeting the RNA m6A reader IGF2BP3 in ovarian cancer.

Based on its absence in normal tissues and its role in tumorigenesis and tumor progression, insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3), a reader of N6-methyladenosine (M6A) on RNA, represents a putative valuable and specific target for some cancer therapy. In this study, we performed bioinformatic analysis and immunohistochemistry (IHC) to find that IGF2BP3 was highly expressed in tumor epithelial cells and fibroblasts of ovarian cancer (OC), and was associated with poor prognosis, metastasis, and chemosensitivity in OC patients. In particular, we discovered that knockdown IGF2BP3 expression inhibited the malignant phenotype of OC cell lines by decreasing the protein levels of c-MYC, VEGF, CDK2, CDK6, and STAT1. To explore the feasibility of IGF2BP3 as a therapeutic target for OC, a small molecular AE-848 was designed and screened by molecular operating environment (MOE), which not only could duplicate the above results of knockdown assay but also reduced the expression of c-MYC in M2 macrophages and tumor-associated macrophages and promoted the cytokine IFN-γ and TNF-α secretion. The pharmacodynamic models of two kinds of OC bearing animals were suggested that systemic therapy with AE-848 significantly inhibited tumor growth by reducing the expression of tumor-associated antigen (c-MYC/VEGF/Ki67/CDK2) and improving the anti-tumor effect of macrophages. These results suggest that AE-848 can inhibit the growth and progression of OC cells by disrupting the stability of the targeted mRNAs of IGF2BP3 and may be a targeted drug for OC treatment.

Laminins in tumor-derived exosomes upregulated by ETS1 reprogram omental macrophages to promote omental metastasis of ovarian cancer.

Tumor-derived exosomes participate in omental metastatic colonization of ovarian cancer by inducing an adaptive response in the tumor microenvironment. However, cell-cell communication via exosomes between primary tumor cells and the microenvironment of distant omentum and the mechanism of pre-metastatic niche formation are poorly understood. Here, we demonstrated that ETS1-overexpressing ovarian cancer cells secreted larger exosomes with higher laminin levels. In addition, ovarian cancer exosomes could be taken up by omental macrophages through integrin and laminin interaction. Compared with control exosomes, exosomes derived from ETS1-overexpressing ovarian cancer cells (LV-ETS1 Exos) stimulated the polarization of more macrophages toward the M2 phenotype (CD163 marker), as well as the production of more CXCL5 and CCL2 in macrophages, via integrin αvß5/AKT/Sp1 signaling. In vivo experiments showed that LV-ETS1 Exos promoted omental metastasis of ovarian cancer by mediating the tumor-promoting effect of macrophages, which could be neutralized by integrin ανß5 inhibitor cilengitide. These results indicated that ETS1 could drive ovarian cancer cells to release exosomes with higher laminin levels, thereby accelerating the exosome-mediated pro-metastatic effects of omental macrophages via the integrin αvß5/AKT/Sp1 signaling pathway, and the integrin ανß5 inhibitor cilengitide could inhibit omental metastasis of ovarian cancer driven by tumor-derived exosomes.

Impacts of Cys392, Asp393, and ATP on the FAD Binding, Photoreduction, and the Stability of the Radical State of Chlamydomonas reinhardtii Cryptochrome.

Plant cryptochromes (CRYs) are blue-light receptors that regulate light-dependent growth, development, and circadian rhythms. A flavin adenine dinucleotide (FAD) cofactor is bound to the photolyase homology region (PHR) of plant CRYs and can be photoreduced to a neutral radical state under blue light. This photoreaction can trigger subsequent signal transduction. Plant CRYs can also bind an ATP molecule adjacent to FAD in a pocket of the PHR. Chlamydomonas reinhardtii contains a single plant CRY, named Chlamydomonas photolyase homologue 1 (CPH1). In CPH1, Cys392 and Asp393 are located near the FAD cofactor. Here we have shown that replacing Cys392 with Ser has little effect on the properties of CPH1. The C392N mutant, however, showed a faster photoreduction rate than wild-type CPH1, together with a significantly lower oxidation rate of the neutral radical state. Substituting an Asn residue for Asp393 in CPH1 improved the binding affinity for FAD as well as the stability of the neutral radical, but photoreduction in the case of this mutant was severely inhibited. In the presence of ATP, CPH1 and its mutants exhibited significantly higher binding affinity for FAD and slower oxidation of the neutral radical. These results reveal that the residues at site 392 and the presence of ATP can tune the stability of the neutral radical, that the Asp residue at site 393 is crucial for photoreduction, and that the photoreduction rate is not determined merely by the stability of the neutral radical in CPH1.