Involvement of reactive oxygen species in aclarubicin-induced death of human trisomic and diabetic fibroblasts

Aclarubicin: contemporary insights into its mechanism of action, toxicity, pharmacokinetics, and clinical standing

Aclarubicin (aclacinomycin A) is one of the anthracycline antineoplastic antibiotics with a multifaceted mechanism of antitumor activity. As a second-generation drug, it offers several advantages compared to standard anthracycline drugs such as doxorubicin or daunorubicin, which could position it as a potential blockbuster drug in antitumor therapy. Key mechanisms of action for aclarubicin include the inhibition of both types of topoisomerases, suppression of tumor invasion processes, generation of reactive oxygen species, inhibition of chymotrypsin-like activity, influence on cisplatin degradation, and inhibition of angiogenesis. Therefore, aclarubicin appears to be an ideal candidate for antitumor therapy. However, despite initial interest in its clinical applications, only a limited number of high-quality trials have been conducted thus far. Aclarubicin has primarily been evaluated as an induction therapy in acute myeloid and lymphoblastic leukemia. Studies have indicated that aclarubicin may hold significant promise for combination therapies with other anticancer drugs, although further research is needed to confirm its potential. This paper provides an in-depth exploration of aclarubicin's diverse mechanisms of action, its pharmacokinetics, potential toxicity, and the clinical trials in which it has been investigated.

Efficacy of doxorubicin-transferrin conjugate in apoptosis induction in human leukemia cells through reactive oxygen species generation

Background

Doxorubicin (DOX) is a small molecular cytotoxic agent that can be transferred efficiently to cancer cells by nanocarriers. This anthracycline antibiotic serves as an effective anti-neoplastic drug against both hematological and solid malignancies. Here, we set out to assess the capacity of a novel doxorubicin - transferrin conjugate (DOX-TRF) to provoke apoptosis in human normal and leukemia cells through free radicals produced via a redox cycle of doxorubicin (DOX) when released from its conjugate.

Methods

After DOX-TRF exposure, we determined the time-course of apoptotic and necrotic events, the generation of reactive oxygen species (ROS), changes in mitochondrial membrane potential, as well as alterations in cytochrome c levels and intracellular calcium concentrations in human leukemia-derived cell lines (CCRF-CEM, K562 and its doxorubicin-resistant derivative K562/DOX) and normal peripheral blood-derived mononuclear cells (PBMC).

Results

We found that DOX-TRF can induce apoptosis in all leukemia-derived cell lines tested, which was associated with morphological changes and decreases in mitochondrial membrane potential. In comparison to free DOX treated cells, we observed a time-dependency between a higher level of ROS generation and a higher drop in mitochondrial membrane potential, particularly in the doxorubicin-resistant cell line. In addition, we found that the apoptotic cell death induced by DOX-TRF was directly associated with a release of cytochrome c from the mitochondria and an increase in intracellular calcium level in all human leukemia-derived cell lines tested.

Conclusions

Our data indicate that DOX-TRF is considerably more cytotoxic to human leukemia cells than free DOX. In addition, we show that DOX-TRF can effectively produce free radicals, which are directly involved in apoptosis induction.

Activation of apoptotic pathway in normal, cancer ovarian cells by epothilone B

The epothilones, a new class of microtubule-targeting agents, seem to be a very promising alternative to the current strategy of cancer treatment. We have analyzed the aspects of epothilone B (Epo B) on cellular metabolism of tumor (OV-90) and normal (MM 14) ovarian cells. The observed effects were compared with those of paclitaxel (PTX), which is now a standard for the treatment of ovarian cancer. The results provide direct evidence that Epo B is considerably more cytotoxic to human OV-90 ovarian cancer cells than PTX. We have found, that antitumor efficacy of this new drug is related to its apoptosis-inducing ability, which was confirmed during measurements typical markers of the process. Epo B induced changes in morphology of cells, mitochondrial membrane potential and cytochrome c release. Also a slight increase of the intracellular calcium level was observed. Moreover, we have found that ROS production, stimulated by Epo B, is directly involved in the induction of apoptosis via mitochondrial pathway.