Luis Miguel Carrasco-Diaz

Background: Colorectal cancer (CRC) has traditionally been treated with genotoxic chemotherapy to activate pro-apoptotic proteins to induce anticancer effects. However, cancer cells develop resistance to apoptosis, which leads to recurrence and poor prognosis. Moreover, this kind of therapy has been shown to be highly toxic to healthy tissues and, therefore, to patients. To overcome this issue, we developed a self-assembly tumor-targeted nanoparticle, T22-DITOX-H6, that incorporates the T22 peptide (a CXCR4 ligand) to selectively target cells overexpressing CXCR4, fused to the catalytic domain of diphtheria toxin, that exhibits a potent cytotoxic effect on these CXCR4+ cancer cells that exhibits potent cytotoxic effects on CXCR4-overexpressing cancer cells through the activation of pyroptosis, an immunogenic type of cell death. Methods: Colorectal CXCR4-expressing tumor cells (CT26-CXCR4+) were implanted subcutaneously into immunocompetent mice to study the effects of T22-DITOX-H6 treatment on tumor growth, cell death and innate immune cell recruitment to the tumor. Results: Here, we demonstrated that the T22-DITOX-H6 nanoparticle selectively activated pyroptosis, an immunogenic cell death that differs from apoptosis, leading to cell death in CXCR4-expressing cells, without affecting the viability of CXCR4-lacking cells. In addition, the nanoparticle administered to tumor-bearing mice induced a local antitumor effect due to the selective activation of pyroptosis in CXCR4+ targeted cancer cells. Biochemical analysis of plasma and histological analysis of non-tumor tissues revealed no differences between the groups. Remarkably, pyroptosis activation stimulates eosinophil infiltration into the tumor microenvironment, an effect recently reported to have an anti-tumorigenic function. Conclusion: These results highlight the dual role of CXCR4-targeted cytotoxic nanoparticle in eliminating cancer cells and boosting the self-immune response without compromising healthy organs.

Hydroxytyrosol (HT), the main representative of polyphenols of olive oil, has been described as one of the most powerful natural antioxidants, also showing anti-inflammatory, antimicrobial, cardioprotective and anticancer activity in different type of cancers, but has been little studied in hematological neoplasms. The objective of this work was to evaluate the anticancer potential of HT in acute human leukemia T cells (Jurkat and HL60) and the anti-inflammatory potential in murine macrophages (Raw264.7). For this, cytotoxicity tests were performed for HT, showing IC₅₀ values, at 24 h, for Jurkat, HL60 and Raw264.7 cells, of 27.3 µg·mL⁻¹, 109.8 µg·mL⁻¹ and 45.7 µg·mL⁻¹, respectively. At the same time, HT caused cell arrest in G₀/G₁ phase in both Jurkat and HL60 cells by increasing G₀/G₁ phase and significantly decreasing S phase. Apoptosis and cell cycle assays revealed an antiproliferative effect of HT, decreasing the percentage of dividing cells and increasing apoptosis. Furthermore, HT inhibited the PI3K signaling pathway and, consequently, the MAPK pathway was activated. Inflammation tests revealed that HT acts as an anti-inflammatory agent, reducing NO levels in Raw264.7 cells previously stimulated by lipopolysaccharide (LPS). These processes were confirmed by the changes in the expression of the main markers of inflammation and cancer. In conclusion, HT has an anticancer and anti-inflammatory effect in the cell lines studied, which were Raw264.7, Jurkat, and HL60, and could be used as a natural drug in the treatment of liquid cancers, leukemias, myelomas and lymphomas.