The effects of daunomycin antibiotic on histone H(1): thermal denaturation and fluorescence spectroscopy studies

Chemical-induced phase transition and global conformational reorganization of chromatin

Chemicals or drugs can accumulate within biomolecular condensates formed through phase separation in cells. Here, we use super-resolution imaging to search for chemicals that induce phase transition within chromatin at the microscale. This microscopic screening approach reveals that adriamycin (doxorubicin) - a widely used anticancer drug that is known to interact with chromatin - specifically induces visible local condensation and global conformational change of chromatin in cancer and primary cells. Hi-C and ATAC-seq experiments systematically and quantitatively demonstrate that adriamycin-induced chromatin condensation is accompanied by weakened chromatin interaction within topologically associated domains, compartment A/B switching, lower chromatin accessibility, and corresponding transcriptomic changes. Mechanistically, adriamycin complexes with histone H1 and induces phase transition of H1, forming fibrous aggregates in vitro. These results reveal a phase separation-driven mechanism for a chemotherapeutic drug.

DNA methylation changes of apoptotic genes in organogenesis stage of mice embryos by maternal chlorpyrifos induction

The continued use of pesticides is one of the requirements of modern agriculture. Investigations have shown that pesticides can alter gene methylation and expression and subsequently may lead to abortion or birth of embryos with teratogenic disorders. In present study, 30 female NMRI mouse were divided in three experimental groups which in the CPF group, intraperitoneal chlorpyrifos was injected, in the sham group, DMSO was injected, and the control group without injection. The mice were mated and utinized 10 days' post gestation. The number of embryos in each fertilized female, maternal weight, and liver fibrosis was evaluated. The apoptosis pathway genes (caspase3, caspase9) and protein expressions (pro-caspase3, caspase3) of the embryos were evaluated with qRT-PCR and western blot, respectively. The DNA methylation of caspase3 and caspase9 were also assessed. The number of embryos and obtained maternal weight from the CPF group was significantly lower than other two groups. The mRNA expression of Caspase3 and Caspase9 were significantly higher in the CPF group. The protein expression evaluation confirmed the results achieved at the mRNA level. The percentage of Caspase9 DNA methylation in embryos collected from the CPF group was higher compared to the others. It can be considered that consumption of chlorpyrifos toxin can alter the DNA methylation and increase the expression of apoptotic genes. Therefore, continuous use of chlopyrifos may affect pregnancy by increasing the apoptosis pathway in the developing embryos which may lead to abortion or teratogenic disorders in newborn infants.

Affinity of anticancer drug, daunomycin, to core histones in solution: comparison of free and cross-linked proteins

AIM

The interaction of anthracycline anticancer drugs with chromatin, nucleosomes and histone H1 has been extensively studied. In the present study, for the first time, we have investigated the binding of anthracycline antibiotic, daunomycin, to free and cross-linked thymus core histones (CL-core) in solution and in the absence of DNA.

METHODS

Fluorescence, UV/Vis spectroscopy and equilibrium dialysis techniques were used.

RESULTS

The UV spectroscopy results show that daunomycin induces hypochromicity in the absorption spectra of the core histones. Fluorescence emission intensity is decreased upon daunomycin binding and the process is concentration dependent. The equilibrium dialysis shows that the binding is positive cooperative with the binding sites as Scatchard plot and Hill Coefficient confirm it.

CONCLUSION

The results suggest that daunomycin shows much higher affinity to core histones free in solution than to CL-core, implying that the binding is most likely due to the accessibility of these proteins to the environment. It is suggested that daunomycin binds strongly to open state of histones, such as in tumor cells, rather than to their compact structure seen in normal chromatin.

The anthracycline antibiotics: antitumor drugs that alter chromatin structure

Anthracycline antibiotics are an important group of antitumor drugs widely used in cancer chemotherapy. However, despite the increasing interest in these chemotherapeutic agents, their mechanism of action is not yet completely understood. Here, we review what is currently known about the molecular mechanisms involved with special emphasis on the interaction of these drugs with chromatin and its constitutive components: DNA and histones. The evidence suggests that one very important component of the activity of these drugs is the result of these manifold interactions that lead to a chromatin unfolding and aggregation. This chromatin structural disruption is likely to interfere with the metabolic processes of DNA (replication and transcription) and it may play an important role in the apoptosis undergone by the cells upon treatment with these drugs.

Binding of antitumor antibiotic daunomycin to histones in chromatin and in solution

Daunomycin is an anticancer drug that is well-known to interact with DNA in chromatin. Using a compositionally defined chicken erythrocyte chromatin fraction, we have obtained conclusive evidence that the drug is also able to interact with chromatin-bound linker histones without any noticeable binding to core histones. The drug can interact in an equal fashion with both histone H1 and H5 and to a greater extent with core histones H3/H4 and H2A/H2B as free proteins in solution. Thus, the binding of daunomycin to linker histones in the chromatin fiber is most likely due to the well-known higher accessibility of these histones to the surrounding environment of the fiber. Binding of daunomycin to linker histones appears to primarily involve the trypsin-resistant (winged-helix) domain of these proteins. The studies described here reveal the occurrence of a previously undisclosed mechanism for the antitumor activity of anthracycline drugs at the chromatin level.

Interaction of daunomycin antibiotic with histone H(1): ultraviolet spectroscopy and equilibrium dialysis studies

Using ultraviolet spectroscopy and equilibrium dialysis techniques, we have investigated the interaction of anticancer drug, daunomycin with calf thymus histone H(1) chromosomal protein in 20 mM phosphate buffer, pH 7.0, 1 mM EDTA at room temperature. The UV spectroscopy results show that daunomycin (5.0-100 microM) decreases the absorbance of histone H(1) at 210-230 nm and induces hypochromicity in the absorption spectrum of the protein. The equilibrium dialysis data show that daunomycin binds to histone H(1) and the binding process is positive cooperative with two binding sites as Scatchard plot and Hill coefficient confirm it. The results suggest that daunomycin binds to histone H(1) and changes its conformation.