Bleomycin

Bleomycin can be used as a fibrogenic agent in animal models of experimentally induced pulmonary fibrosis.  In vitro toxicity studies have indicated that in primary pulmonary artery endothelial cells (PAEC), the compound causes apoptosis via the extrinsic apoptotic pathway (A15408) (Mungunsukh et al, 2010).

The native confirmation of DNA is called B-DNA, however another confirmation is A-DNA. They are both right-handed helices, but A-DNA has a larger diameter and is shorter.  Different dimensions of these forms determine the different size of major and minor grooves. Researchers studied the conformational transition of DNA in living cells resulting from pharmacologically induced strand breaks. HeLa cells were treated with Bleomycin in various concentrations (50 µM, 150 µM and 500 µM) to induce DNA damage.  Changes in the cell were detected using Raman micro-spectroscopy.  Bleomycin treatment  at 500 uM led to cell apoptosis detected as spectral changes indicating water loss, increase of cellular material density and formation of apoptotic bodies.  Chromatin fragmentation, a hallmark of cell death, was observed with fluorescence imaging (Czaja et al, 2022).

Bleomycin is used in combination with other antineoplastic agents in studying lymphomas, testicular carcinomas, and squamous cell carcinomas.  Researchers found that the human L-carnitine transporter (hCT2) is involved in Bleomycin-A5 uptake.  NT2/D1 human testicular cancer cells which highly express hCT2 are very sensitive to Bleomycin-A5.  Data suggest that hCT2 can mediate the uptake of Bleomycin A5 (Aouida et al, 2010).

In cell culture experiments with Bleomycins and BLM carbohydrates conjugated to microbubbles, it has been demonstrated that Bleomycins are tumor-seeking molecules.  Biotinylate Bleomycin A5 was attached to microbubbles, and a conjugate-containing solution was passed over a monolayer of MCF-7 cells.  The microbubbles adhered to the MCF-7 cells.  The conjugate did not bind to a normal breast cell line or to matched noncancer cell lines.  No binding occurred if the microbubbles lacked conjugated Bleomycin A5 or if the microbubble lacked the carbohydrate moiety (Chapuis et al, 2009).

A well-known characteristic of tumor cells is the Warburg effect, that is the propensity of tumor cells to produce increased ATP via glycolysis rather than by mitochondrial oxidative phosphorylation.  The shift to glycolysis is accompanied by upregulation of glucose transporters to provide the greater amounts of glucose needed to support increased glycolysis.  If authors treated two wild-type cell lines (normal WI-38 and normal kidney CCD-1105 KIDTr cells) with the inhibitor rotenone (a mitochondrial complex 1 inhibitor), this forced these cells to use increase glycolysis in the same fashion as tumor cells and this resulted in an enhanced ability to incorporate BLM-Cy5.  The finding implies that the BLM saccharide moiety may be able to deliver other cytotoxins selectively to tumor cells (Mobasheril, 2005). 

Aouida M, Poulin P and Ramotar (2010)  The human carnitine transporter SLC22A16 mediates high affinity uptake of the anticancer polyamine analogue Bleomycin-A5. J. Biol. Chem. 285:6275-6284

Chapuis J, Schmaltz RM, Tsosie KS, Belohlavek M and Hecht SM (2009)  Carbohydrate dependent targeting of cancer cells by Bleomycin-microbubble conjugates. J. Am. Chem. Soc. 131(7):2438-2439

Czaja M et al (2022) Raman research on Bleomycin-induced DNA strand breaks and repair processes in living cells. Int. J. Molec. Sci. 23(7):3524 

Mobasheril, A, Richardson S,  Mobasheri R, Shakibaei M, Hoyland, J (2005)  Hypoxia inducible factor-1 and facilitative glucose transporters GLUT1 and GLUT3: Putative molecular components of the oxygen and glucose sensing apparatus in articular chondrocytes. Histol. Histopathol.  20(4):1327-1338   PMID 16136514

Mulsant P, Gatignol A, Dalens M and Tiraby, G (1988) Phleomycin resistance as a dominant selectable marker in CHO cells. Som. Cell and Mol.  Gen. 14(3):243–252  PMID: 2453083

Mungunsukh O, Griffin AJ, Lee YH, Day RM (2010)  Bleomycin induces the extrinsic apoptotic pathway in pulmonary endothelial cells. Am J Physiol Lung Cell Mol Physiol. 298(5):L696-703  PMID 20154224

Schroeder BR et al (2014)  The disaccharide moiety of Bleomycin facilitates uptake by cancer cells.  J. Am. Chem Soc. 136(39):13641-13656 

Yang L, Yang S, Tai K, Chou M and Yang J (2004)  MEK inhibition enhances Bleomycin A5-induced apoptosis in an oral cancer cell line: Signaling mechanisms and therapeutic opportunities. J. Oral Path. and Med. 33(1):37-45