Role of carbohydrate moiety of bleomycin-A2 in caspase-3 activation and internucleosomal chromatin fragmentation in apoptosis of laryngeal carcinoma cells

Advances in heterocycles as DNA intercalating cancer drugs

The insertion of a molecule between the bases of DNA is known as intercalation. A molecule is able to interact with DNA in different ways. DNA intercalators are generally aromatic, planar, and polycyclic. In chemotherapeutic treatment, to suppress DNA replication in cancer cells, intercalators are used. In this article, we discuss the anticancer activity of 10 intensively studied DNA intercalators as drugs. The list includes proflavine, ethidium bromide, doxorubicin, dactinomycin, bleomycin, epirubicin, mitoxantrone, ellipticine, elinafide, and echinomycin. Considerable structural diversities are seen in these molecules. Besides, some examples of the metallo-intercalators are presented at the end of the chapter. These molecules have other crucial properties that are also useful in the treatment of cancers. The successes and limitations of these molecules are also presented.

Anti-cancer agents and reactive oxygen species modulators that target cancer cell metabolism

Traditionally the perspective on reactive oxygen species (ROS) has centered on the role they play as carcinogenic or cancer-causing radicals. Over the years, characterization and functional studies have revealed the complexity of ROS as signaling molecules that regulate various physiological cellular responses or whose levels are altered in various diseases. Cancer cells often maintain high basal level of ROS and are vulnerable to any further increase in ROS levels beyond a certain protective threshold. Consequently, ROS-modulation has emerged as an anticancer strategy with synthesis of various ROS-inducing or responsive agents that target cancer cells. Of note, an increased carbohydrate uptake and/or induction of death receptors of cancer cells was exploited to develop glycoconjugates that potentially induce cellular stress, ROS and apoptosis. This mini review highlights the development of compounds that target cancer cells by taking advantage of redox or metabolic alteration in cancer cells.

Deglycosylated bleomycin has the antitumor activity of bleomycin without pulmonary toxicity

Bleomycin (BLM) is a potent anticancer drug used to treat different malignancies, mainly lymphomas, germ cell tumors, and melanomas. Unfortunately, BLM has major, dose-dependent, pulmonary toxicity that affects 20% of treated individuals. The most severe form of BLM-induced pulmonary toxicity is lung fibrosis. Deglyco-BLM is a molecule derived from BLM in which the sugar residue d-mannosyl-l-glucose disaccharide has been deleted. The objective of this study was to assess the anticancer activity and lung toxicity of deglyco-BLM. We compared the antitumor activity and pulmonary toxicity of intraperitoneally administrated deglyco-BLM and BLM in three rodent models. Pulmonary toxicity was examined in depth after intratracheal administration of both chemotherapeutic agents. The effect of both drugs was further studied in epithelial alveolar cells in vitro. We demonstrated in rodent cancer models, including a human Hodgkin's lymphoma xenograft and a syngeneic melanoma model, that intraperitoneal deglyco-BLM is as effective as BLM in inducing tumor regression. Whereas the antitumor effect of BLM was accompanied by a loss of body weight and the development of pulmonary toxicity, deglyco-BLM did not affect body weight and did not engender lung injury. Both molecules induced lung epithelial cell apoptosis after intratracheal administration, but deglyco-BLM lost the ability to induce caspase-1 activation and the production of ROS (reactive oxygen species), transforming growth factor-β1, and other profibrotic and inflammatory cytokines in the lungs of mice and in vitro. Deglyco-BLM should be considered for clinical testing as a less toxic alternative to BLM in cancer therapy.

Synergistic anticancer activity of dietary tea polyphenols and bleomycin hydrochloride in human cervical cancer cell: Caspase-dependent and independent apoptotic pathways

Bleomycin is a chemotherapeutic agent that is frequently used in the treatment of various cancers. Bleomycin causes serious adverse effects via antioxidant defense abnormalities against reactive oxygen species (ROS). However, the current cervical cancer monodrug therapy strategy has failed to produce the expected outcomes; hence, combinational therapies are gaining great interest. Tea polyphenols are also effective antioxidative and chemo-preventive agents. However, the combined effect of tea polyphenol (TPP) and bleomycin (BLM) against cervical cancer remains unknown. In this study, we focused on the potential of TPP on BLM anticancer activity against cervical cancer cells. Cervical cancer cells (SiHa) were treated with various concentrations of TPP, BLM and TPP combined with BLM (TPP-BLM), and their effects on cell growth, intracellular reactive oxygen species, poly-caspase activity, early apoptosis and the expression of caspase-3, caspase-8 and caspase-9, Bcl-2 and p53 were assessed. The MTT assay revealed that the SiHa cells were less sensitive to growth inhibition by TPP treatment compared with both BLM and the combination therapy. Nuclear staining indicated that exposure to TPP-BLM increased the percentage of apoptotic nuclei compared with a mono-agent treatment. Caspase activation assay demonstrated that proportion of early and late apoptotic/secondary necrotic cells was higher in the cells treated with the combination therapy than in those treated with either TPP or BLM alone. The TPP-BLM treatment synergistically induced apoptosis through caspase-3, caspase-8 and caspase-9 activation, Bcl-2 upregulation and p53 overexpression. This study suggests that TPP-BLM may be used as an efficient antioxidant-based combination therapy for cervical cancer.