Anticancer Activity and Mechanism of Action of kla-TAT Peptide

Therapeutic peptides for chemotherapy: Trends and challenges for advanced delivery systems

The past decades witnessed an increasing interest in peptides as clinical therapeutics. Rightfully considered as a potential alternative for small molecule therapy, these remarkable pharmaceuticals can be structurally fine-tuned to impact properties such as high target affinity, selectivity, low immunogenicity along with satisfactory tissue penetration. Although physicochemical and pharmacokinetic challenges have mitigated, to some extent, the clinical applications of therapeutic peptides, their potential impact on modern healthcare remains encouraging. According to recent reports, there are more than 400 peptides under clinical trials and 60 were already approved for clinical use. As the demand for efficient and safer therapy became high, especially for cancers, peptides have shown some exciting developments not only due to their potent antiproliferative action but also when used as adjuvant therapies, either to decrease side effects with tumor-targeted therapy or to enhance the activity of anticancer drugs via transbarrier delivery. The first part of the present review gives an insight into challenges related to peptide product development. Both molecular and formulation approaches intended to optimize peptide's pharmaceutical properties are covered, and some of their current issues are highlighted. The second part offers a comprehensive overview of the emerging applications of therapeutic peptides in chemotherapy from bioconjugates to nanovectorized therapeutics.

Inhibition of Tumor Growth against Chemoresistant Cholangiocarcinoma by a Proapoptotic Peptide Targeting Interleukin-4 Receptor

Cholangiocarcinoma (CCA) has a poor prognosis and high chemoresistance. Interleukin-4 receptor (IL-4R) is overexpressed in several cancer cells and plays a crucial role in tumor progression and drug resistance. IL4RPep-1, an IL-4R-binding peptide, has been identified by phage display and used for tumor targeting. In this study, we exploited IL4RPep-1 to guide the tumor-specific delivery of a proapoptotic peptide to chemoresistant CCA, thereby inhibiting tumor growth. Immunohistochemistry of human primary CCA tissues showed that IL-4R levels were upregulated in moderately to poorly differentiated types, and higher levels of IL-4R are correlated with lower survival rates in patients with CCA. IL4RPep-1 was observed to preferentially bind with high IL-4R-expressing KKU-213 human CCA cells, whereas it barely bound with low IL-4R-expressing KKU-055 cells. A hybrid of IL4RPep-1 and a proapoptotic peptide (KLAKLAK)2 (named as IL4RPep-1-KLA) induced cytotoxicity and apoptosis in KKU-213 cells and increased those levels induced by 5-fluorouracil (5-FU). IL4RPep-1-KLA was internalized in the cells and colocalized with mitochondria. Whole-body fluorescence imaging and immunohistochemical analysis of tumor tissues showed the homing of IL4RPep-1-KLA as well as IL4RPep-1 to KKU-213 tumor in mice. Systemic administration of IL4RPep-1-KLA efficiently inhibited KKU-213 tumor growth, whereas treatment with 5-FU alone did not significantly inhibit tumor growth in mice. No significant systemic side effects including liver toxicity and immunotoxicity were observed in mice during peptide treatments. These findings suggest that IL4RPep-1-KLA holds potential as a targeted therapeutic agent against chemoresistant CCA.