Ignacio Esteban León

Introduction: Osteosarcoma (OS) is the most common primary malignant bone tumor in children and young adults and remains associated with poor clinical outcomes due to recurrence, metastasis, and resistance to conventional chemotherapy. In recent years, copper-based compounds have emerged as promising anticancer agents because of their unique redox properties and ability to target multiple cellular pathways. Methods: In this work, we synthesized and characterized two hydrazone ligands, ( E )- N ′-(2-hydroxybenzylidene)furan-2-carbohydrazide (L1) and ( E )- N ′-(2-hydroxybenzylidene)-4-methoxybenzohydrazide (L2), together with their corresponding Cu(II) complexes, CuL1 and Cu ₂ L2 ₂ . The compounds were characterized by elemental analysis, spectroscopic techniques, high-resolution mass spectrometry, and single-crystal X-ray diffraction. The biological activity of the complexes was evaluated in human MG-63 osteosarcoma cells using the MTT assay. Reactive oxygen species (ROS) generation was assessed using dihydrorhodamine 123 (DHR123) after 24 h of treatment to gain insight into their mechanism of action. Their activity was further evaluated in 3D MG-63 osteosarcoma spheroids using a resazurin-based viability assay, while anti-migratory effects were assessed using the spheroid spreading assay. Results: Biological evaluation demonstrated that coordination to Cu(II) converted the inactive hydrazone ligands into highly potent anticancer agents. Both Cu(II) complexes exhibited potent cytotoxic activity in 2D cell cultures, with IC ₅₀ values in the low micromolar range and significantly higher activity than cisplatin, whereas the free ligands showed no significant antiproliferative effect. Furthermore, treatment with CuL1 and Cu ₂ L2 ₂ induced a rapid increase in intracellular ROS, suggesting that oxidative stress contributes to their mechanism of action. The antitumor potential of the complexes was further assessed using multicellular tumor spheroids, where both compounds reduced spheroid viability, altered spheroid morphology, and significantly inhibited spheroid-derived cell migration. Discussion: Among the compounds studied, the binuclear complex Cu ₂ L2 ₂ displayed the highest antiproliferative activity in both 2D and 3D models. Overall, our findings demonstrate that coordination of hydrazone ligands to Cu(II) markedly enhances their biological activity and identify CuL1 and particularly the binuclear complex Cu ₂ L2 ₂ as promising candidates for the development of new copper-based therapeutics against osteosarcoma.

La Universidad Latinoamericana se configura como una institución dinámica y contradictoria, atravesada por conflictos sociales. En la formación en salud predominan modelos biologicistas, médico hegemónicos, hospital céntricos y mercantilistas, objeto de crítica en la discusión académica. En contraposición, la Atención Primaria de la Salud constituye un espacio donde se tensionan modelos de formación e intervención, reconfigurando el papel de la extensión universitaria, priorizando su función adjetiva y redefiniendo los enfoques del quehacer docente y de la investigación.

Introduction: Osteosarcoma (OS) is the most common primary malignant bone tumor in children and young adults, with poor prognosis due to relapse, metastasis, and chemoresistance. The search for novel metal-based therapeutics has highlighted copper complexes as promising candidates. Here, we report the in vitro and in vivo antitumor activity of a tetranuclear Cu(II)-hydrazone complex (Cu₄L₄) derived from (E)-5-chloro-N′-(2-hydroxy-3-methoxybenzylidene)thiophene-2-carbohydrazide. Results: Cytotoxic assays on MG-63 OS cells revealed potent activity with an IC₅₀ of 0.50 ± 0.04 µM, significantly surpassing its free ligand (IC₅₀ = 13.9 ± 1.6 µM) and cisplatin (IC₅₀ = 39.0 ± 1.8 µM). This tetranuclear complex outperforms mononuclear Cu-hydrazones analogs (e.g., 4-fold vs. CuHL1, 2-fold vs. CuHL2, 5-fold vs. CuHL3, 17-fold vs. CuHL4,), and Cu₄L₄ also exhibits reduced clonogenic survival, induces reactive oxygen species production, and promotes late apoptosis as a main mechanism, being the main mechanism of action involved in anticancer activity. In multicellular tumor spheroids, the complex maintained strong cytotoxicity (IC₅₀ = 4.11 ± 0.12 µM), impaired spheroid integrity, and markedly inhibited cell migration at sub-IC₅₀ concentrations. The tetranuclear architecture confers markedly enhanced antitumor activity relative to the corresponding mononuclear Cu–hydrazone complexes (e.g., 2-fold vs. CuHL1, 4-fold vs. CuHL2, 2-fold vs. CuHL3). In a xenograft model, sustained administration of Cu₄L₄ (2 mg/kg, i.p., twice weekly) inhibited tumor growth by 43.6%, reduced mitotic index, and increased necrotic area without significant systemic toxicity. Conclusions: Overall, Cu₄L₄ displayed potent and selective antitumor activity against OS cells in 2D, 3D, and in vivo models, underscoring copper–hydrazone complexes as promising scaffolds for the development of new therapies against OS.

Triple‐negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited therapeutic treatments. This study evaluates the anticancer activity and mode of action of the copper(II) complex [Cu(HL ¹ )(NO ₃ )H ₂ O]·H ₂ O ( CuHL ¹ ), derived from (E)‐N’‐(2‐hydroxy‐3‐methoxybenzylidene)furan‐2‐carbohydrazide ( H ₂ L ¹ ), against a panel of TNBC cell lines (MDA‐MB‐231, MDA‐MB‐468, MDA‐MB‐157, HCC1806). CuHL ¹ exhibits potent cytotoxicity in the low micromolar range (IC ₅₀ ≈ 2 µM), surpassing cisplatin by up to 81‐fold. In MDA‐MB‐231 cells, CuHL ¹ inhibits colony formation and induced reactive oxygen species (ROS) generation in a concentration‐dependent manner. Moreover, CuHL ¹ triggers apoptosis as evidenced by Annexin V/PI staining and the modulation of Bax, Bcl‐2, caspase‐3, and cleaved caspase‐3 protein levels. Label‐free quantitative proteomics reveal 34 differentially expressed proteins, implicating pathways related to heat shock response, protein folding, lipid metabolism, and cell migration. Notably, CuHL ¹ downregulates BCAR3, AJUBA, MPZL1, TP53, FASN, and HMGCS1, suggesting inhibition of prometastatic and lipid biosynthetic processes. Functional assays confirm reduced migratory capacity in MDA‐MB‐231 cells. These findings position CuHL ¹ as a promising candidate for TNBC therapy, meriting further in vivo evaluation.

A relationship between structural modifications and catalytic activities of dicopper( ii ) complexes with ligands containing different thioether and selenoether substituents.