Gemcitabine resistance in triple-negative breast cancer cells can be reverted by Drosophila melanogaster deoxyribonucleoside kinase in the nucleus or cytosol.

The development of drug resistance to chemotherapeutic agents has consistently presented a challenge in terms of the treatment of patients with triple-negative breast cancer (TNBC). In the present study, gemcitabine (dFdC)-resistant TNBC cells were established, and the effects of lentivirus-deoxyribonucleoside kinase (dNK) and a mutated form of dNK (lentivirus-dNKmut) on reversing the acquired drug resistance in dFdC-resistant TNBC cells were explored. Quantitative PCR and western blotting experiment results suggested that Drosophila melanogaster (Dm)-dNK was stably expressed in the lentivirus-infected MDA-MB-231 and MDA-MB-231R cells in the nucleus or cytosol, and autoradiography experiments revealed similar levels of enzymatic activity in the cells expressing dNK or dNKmut. In vitro cytotoxicity assay revealed that the IC50 values of dFdC were decreased 30~50-fold in the dFdC-resistant MDA-MB-231 cells following lentiviral transfection with dNK or dNKmut, and this effect was associated with a significantly increased rate of apoptosis compared with the cells transfected with the negative control lentivirus. In conclusion, Dm-dNK in the nucleus or cytosol may be a potential candidate for reversing acquired dFdC resistance in TNBC cells, which may form the basis of novel strategies for the treatment of patients with drug-resistant TNBC.

Low dose Emodin induces tumor senescence for boosting breast cancer chemotherapy via silencing NRARP.

PURPOSE: The resistance to 5-FU often limits its clinical effectiveness on breast cancer treatment. Combination therapy thus is employed to overcome this treatment resistance. We here report a potent antitumor effect of Emodin at low dose on chemotherapy sensitivity of MCF-7 breast cancer cells. METHODS: Cell viability, apoptosis, glutathiones (GSH) concentration and Reactive oxygen species (ROS) activity following Emodin and 5-FU treatment was assessed. Cellular senescence following combined treatment and silence of NRARP was examined by senescence-associated ß-galactosidase analysis. Western blot analysis was used to determine changes in the expression of p21, p16, p27, E2F1 and NRARP. RESULTS: Low dose Emodin potentiates 5-FU-induced apoptosis of breast cancer cells, in association with inhibition of NRARP, resulting in cellular senescence. RNA interference of NRARP induced cellular senescence in MCF-7 breast cancer cells. Furthermore, the cellular senescence induced by Emodin and 5-FU treatment could be reverted by pcDNA-NRARP. CONCLUSION: These findings provide preclinical evidence for repurposing use of Emodin in combination with chemotherapeutic agents to treat breast cancer as an alternative salvage regimen.

Synergistic antitumor effect of adenovirus armed with Drosophila melanogaster deoxyribonucleoside kinase and nucleoside analogs for human breast carcinoma in vitro and in vivo.

BACKGROUND: Suicide gene therapy in cancer can selectively kill tumors without damaging normal tissues. Drosophila melanogaster multisubstrate deoxyribonucleoside kinase (Dm-dNK), an original suicide kinase, makes use of the carcinomatous suicide gene therapy for broader substrate specificity and a higher catalytic rate. METHODS: To enhance the anti-tumor efficacy of Dm-dNK and maintain its substrate specificity and safety control in the meantime, the conditionally replicative gene-viral system, ZD55-dNK (which contains the selective replication adenovirus, ZD55, encoded with Dm-dNK), was investigated in pushing a deeper development of this strategy. Selective replication, cell killing efficacy, and cytotoxicity, in combination with chemotherapy, were applied to two breast cell lines (MDA231 and MCF7 cells), two normal cell lines (WI38 and MRC5 cells), and the MCF7 xenograft model in vivo. RESULTS: The preclinical study showed that ZD55-dNK, combined with 2',2'-difluorodeoxycytidine (DFDC), synergistically inhibited adenovirus replication in vitro but maintained specifically cancer cell killing efficacy. ZD55-dNK also greatly improved the antineoplastic effect in vitro and in breast cancer xenograft in vivo. CONCLUSION: The concomitant use of ZD55-dNK and DFDC is possibly a novel and promising approach to breast cancer treatment, and further investigation on the safe control of excessive virus replication and the efficacy of this approach in humans is warranted.

Emodin induces apoptosis of human breast cancer cells by modulating the expression of apoptosis-related genes.

The aim of this study was to investigate the effects of emodin on the proliferation of human breast cancer cells Bcap-37 and ZR-75-30. Cell viability following emodin treatment was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The effects of emodin on apoptosis were determined by flow cytometry using Annexin V-fluorescein isothiocyanate and propidium iodide staining. Quantitative polymerase chain reaction and western blot analysis were used to determine changes in the expression of apoptotic genes and protein, respectively. The effect of emodin on the invasiveness of breast cancer cells was evaluated by Matrigel invasion assay. Treatment of breast cancer cells Bcap-37 and ZR-75-30 with emodin was observed to inhibit the growth and induced apoptosis in a time- and dose-dependent manner. Emodin reduced the level of Bcl-2 and increased levels of cleaved caspase-3, PARP, p53 and Bax. These findings indicate that emodin induces growth inhibition and apoptosis in human breast cancer cells. Emodin may be a potential therapeutic agent for the treatment of breast cancer.

Survivin regulates the expression of VEGF-C in lymphatic metastasis of breast cancer.

BACKGROUND: As a known regulator of apoptosis, survivin has positive relationship with lymphatic metastasis in breast cancer. This study aims to detect the difference in expression between survivin and vascular endothelial growth factor-C (VEGF-C) in treated breast cancer cells and tissues, and to analyze the correlation among survivin, VEGF-C and lymphatic metastasis. METHODS: Plasmid with survivin and VEGF-C shRNA and lentivirus with survivin gene were constructed and transfected into breast cancer cell ZR-75-30. Then the expressions of the two genes were examined using western blot analysis and real-time PCR. The change of invasiveness of breast cancer cells was assessed using matrigel invasion assay. Using immunohistochemistry, the expression of survivin and VEGF-C were analyzed in 108 clinical breast cancer cases with breast cancer tissue and lymph node. RESULTS: Survivin regulated the expression of VEGF-C at both protein and mRNA levels in breast cancer cells. Immunohistochemical analysis showed that the level of VEGF-C expression was significantly related with that of survivin in breast cancer tissues (p<0.05). VEGF-C was found to participate in the process of breast cancer cells invasion mediated by survivin. The co-expression of the two and the single expression of any one took significant difference in positive lymph node (p<0.05). CONCLUSIONS: Survivin takes an important part in regulating the expression of VEGF-C. VEGF-C could influence the invasive ability mediated by survivin. The co-expression of survivin and VEGF-C is more statistically significant to assess lymphatic metastasis in breast cancer. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9193530897100952.