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Vorinostat is a histone deacetylase inhibitor that effectively suppresses cancer-cell proliferation by inducing cell-cycle arrest and/or apoptosis. We now show the involvement of p38 mitogen-activated protein kinase (MAPK) in the regulation of vorinostat-induced apoptosis in MDA-MB-231 human breast cancer cells. Vorinostat induced the hyperacetylation of histone H3, which correlated to apoptosis induction. Vorinostat-induced apoptosis occurred in parallel with the phosphorylation of p38 MAPK and the dephosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2). Knockdown of p38 MAPK prominently abrogated apoptosis induction and was accompanied by decreased caspase-3 cleavage. These findings support the notion that the activation of the p38 MAPK pathway followed by caspase-3 cleavage is responsible for vorinostat-induced apoptosis in MDA-MB-231 cells., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

The anticancer effects of sulforaphane (SFN), which is found in cruciferous vegetables, were studied on KPL-1 human breast cancer cells in vitro and in vivo. Cell proliferation in vitro was assessed by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and tumor growth and metastasis in vivo were examined in orthotopically (right thoracic mammary fat pad) transplanted KPL-1 cells in female athymic BALB/c mice. The MTT assay showed that SFN directly inhibited KPL-1 cell growth in vitro (IC50 at 48 h, 19.1 µM; IC50 at 72 h, 17.8 µM). Athymic mice received a KPL-1 cell transplant, and SFN treatment (intraperitoneal injection of 25 or 50 mg/kg SFN) was started the next day. Mice received five injections each week during the 26-day experimental period (for a total of 20 injections). Compared with the SFN-untreated controls, SFN suppressed primary tumor growth. At the termination of the experiment, the final tumor volume was 686±94 mm3 for the control group, 516±70 mm3 (75% of control value) for the 25 mg/kg SFN group and 351±55 mm3 (51% of control value) for the 50 mg/kg SFN group. The final tumor weight was 571±69 mg in the control group, 416±63 mg (73% of the control value) in the 25 mg/kg SFN group and 338±56 mg (59% of the control value) in the 50 mg/kg SFN group. SFN caused a dose-dependent decrease in the proliferation ratio and an increase in the apoptotic ratio of the primary tumor cells. SFN treatment tended to reduce regional (axillary) lymph node metastasis. Treatment with 50 mg/kg SFN significantly inhibited KPL-1 cell growth in vivo by suppressing cell proliferation and inducing apoptosis, and it tended to reduce axillary lymph node metastasis of KPL-1 human breast cancer cell xenografts in female athymic mice.

N-Methyl-N-nitrosourea (MNU) is a direct-acting alkylating agent that interacts with DNA. Accumulation of mutations may enhance cancer risk in target organs or cause cell death in susceptible tissues or cells when excessive DNA damage is not repaired. MNU targets various organs in a variety of animal species. MNU-induced carcinogenesis can be used as organ-specific animal models for human cancer, and MNU has been most extensively utilized for the induction of mammary cancer in rats. MNU-induced rat mammary tumors possess many similarities to those of human breast cancer, and the model is utilized for screening cancer modulators. MNU-induced cell disruption is also seen in several organs and tissues, especially when MNU is applied before maturity. However, photoreceptor cells in adults are highly sensitive to MNU, which causes cell death due to apoptosis. MNU-induced photoreceptor apoptosis mimics human retinitis pigmentosa and can be used for studies of therapeutic intervention. In this review, the targets of MNU in various animal species are described, and special emphasis is given to therapeutic trials against MNU-induced mammary cancer and retinal degeneration in animal models.

Aim: Sulforaphane (SFN), which is present in cruciferous vegetables, induces growth arrest and/or cell death in cancer of various organs. The involvement of autophagy in the SFN-induced apoptotic death of human breast cancer cells was investigated., Materials and Methods: Cell proliferation and viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and trypan blue exclusion assay. Flow cytometry, immunofluorescence, electron microscopy, and Western blot analysis were used for detection of apoptosis and autophagy, and the role of autophagy was assessed using autophagy inhibitors., Results: SFN dose- and time-dependently retarded the growth and induced cell death in MCF-7 and MDA-MB-231 human breast cancer cells. In MDA-MB-231 cells, 30 μM SFN caused S and G2/M cell-cycle arrest associated with increased p21WAF1 and p27KIP1 levels and decreased cyclin A, cyclin B1 and CDC2 levels. Cell death was due to apoptosis with increased caspase-3 and lowered BCL-2 levels. In addition, the SFN-treated cells exhibited autophagy, as characterized by the appearance of autophagic vacuoles by electron microscopy, the accumulation of acidic vesicular organelles by flow cytometry, and the punctuate patterns of microtubule-associated protein 1 light chain 3 (LC3) by fluorescein microscopy. The levels of LC3-I and -II proteins (processed forms of LC3-I) and LC3 mRNA were increased. Treatment with autophagy inhibitor bafilomycin A1 (but not 3-methyladenine) with SFN significantly enhanced apoptosis, which was accompanied by increases in the level of BAX and the cleavage of caspase-3 and poly(ADP-ribose)polymerase (PARP)-1 and decreases in the mitochondrial membrane potential (ΔΨm)., Conclusion: These results indicate a cytoprotective role of autophagy against SFN-induced apoptosis and that the combination of SFN treatment with autophagy inhibition may be a promising strategy for breast cancer control.