A Small Peptide Increases Drug Delivery in Human Melanoma Cells

Melanoma is the most fatal type of skin cancer and is notoriously resistant to chemotherapies. The response of melanoma to current treatments is difficult to predict. To combat these challenges, in this study, we utilize a small peptide to increase drug delivery to melanoma cells. A peptide library array was designed and screened using a peptide array-whole cell binding assay, which identified KK-11 as a novel human melanoma-targeting peptide. The peptide and its D-amino acid substituted analogue (VPWxEPAYQrFL or D-aa KK-11) were synthesized via a solid-phase strategy. Further studies using FITC-labeled KK-11 demonstrated dose-dependent uptake in human melanoma cells. D-aa KK-11 significantly increased the stability of the peptide, with 45.3% remaining detectable after 24 h with human serum incubation. Co-treatment of KK-11 with doxorubicin was found to significantly enhance the cytotoxicity of doxorubicin compared to doxorubicin alone, or sequential KK-11 and doxorubicin treatment. In vivo and ex vivo imaging revealed that D-aa KK-11 distributed to xenografted A375 melanoma tumors as early as 5 min and persisted up to 24 h post tail vein injection. When co-administered, D-aa KK-11 significantly enhanced the anti-tumor activity of a novel nNOS inhibitor (MAC-3-190) in an A375 human melanoma xenograft mouse model compared to MAC-3-190 treatment alone. No apparent systemic toxicities were observed. Taken together, these results suggest that KK-11 may be a promising human melanoma-targeted delivery vector for anti-melanoma cargo.

Iron Effects on Clostridioides difficile Toxin Production and Antimicrobial Susceptibilities

Despite the benefits of red blood cell (RBC) transfusion therapy, it can render patients vulnerable to iron overload. The excess iron deposits in various body tissues cause severe complications and organ damage such as cardiotoxicity and mold infections. Clostridioides difficile infection (CDI) is the most common cause of nosocomial diarrhea among cancer patients and is associated with significant morbidity and mortality. Our study aims to determine the role of iron overload and the effects of iron chelators on CDI. Our results demonstrated that iron (Fe3+) stimulated the growth of C. difficile with increased colony formation units (CFU) in a dose-dependent manner. Exposure to excess iron also increased the gene expression levels of tcdA and tcdB. The production of C. difficile toxin A, necessary for the pathogenesis of C. difficile, was also elevated after iron treatment. In the presence of excess iron, C. difficile becomes less susceptible to metronidazole with significantly elevated minimum inhibitory concentration (MIC) but remains susceptible to vancomycin. Iron-stimulated colony formation and production of C. difficile toxins were effectively diminished by iron chelator deferoxamine co-treatment. Incorporating iron overload status as a potential factor in developing a risk prediction model of CDI and antibiotic treatment response may aid clinical practitioners in optimizing CDI management in oncology patients.