Synergistic anti-cancer effects of Nigella sativa seed oil and conventional cytotoxic agent against human breast cancer.

OBJECTIVES: Breast cancer is the most commonly diagnosed invasive non-skin malignancy in women worldwide, and it is the leading cause of cancer-related deaths in them. Nigella sativa Linn. seed oil has been found to be effective in cancer treatment as well as having anti-cancer properties in some other types of cancers. The study looked into the synergistic cytotoxic effects of N. sativa Linn. seed oil and doxorubicin in the treatment of human breast cancer cells (MCF-7). METHODS: Nigella sativa Linn. seed oil was used to evaluate its effect on human breast cancer cells, either alone or in conjunction with doxorubicin. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tests were used to examine cell proliferation and cell viability, while phase-contrast inverted microscopy was used to examine cellular morphology. Furthermore, the role of N. sativa seed oil in decreasing cell tumorigenicity features was highlighted by testing the cancer cell migration using the wound healing assay. RESULTS: Results showed that higher concentrations (50 µg/mL) of N. sativa Linn. seed oil changed the breast cancer cell morphology and decreased the cell proliferation and viability. Breast cancer cells treated with black seed oil decreased cell movement after 24 hours compared to the untreated cell in the wound healing assay. Whereas, only the higher concentration of doxorubicin (0.5-2.5 µg/mL) reduced cell proliferation and cell viability. Moreover, the combination treatment of 50 µg/mL of black seed oil with different concentrations of doxorubicin caused a significant cell proliferation reduction and decreased cell viability. The activity was seen optimum at lower concentration (0.1 µg/mL) of doxorubicin. CONCLUSIONS: There was decreased cell proliferation and cell viability when N. sativa seed oil was used alone or in conjunction with doxorubicin in Breast cancer cells (MCF-7) revealing potential opportunities in the field of cancer treatment.

Coupling of a Novel TIMP3 Peptide to Carboxypeptidase G2 for Pro-Drug Activation at the Tumour Site.

Broad-spectrum cytotoxic drugs have been used in cancer therapy for decades. However, their lack of specificity to cancer cells often results in serious side-effects, limiting efficacy. For this reason, antibodies have been used to attempt to specifically target cytotoxic drugs to tumours. One such approach is antibody-directed enzyme prodrug therapy (ADEPT) which uses a tumour-directed monoclonal antibody, coupled to an enzyme, to convert a systemically administered non-toxic prodrug into a toxic one only at the tumour site. Among the main drawbacks of ADEPT is the immunogenicity of the antibody-enzyme complex, which is exacerbated by slow clearance due to size, hence limiting repeated administration. Additionally, the mono-specificity of the antibody could potentially result in drug resistance with repeated administration. We have identified a novel short peptide sequence, p700, derived from a human tissue inhibitor of metalloproteinases-3 (TIMP-3), which binds to and inhibits a number of tyrosine kinase growth factor receptors (VEGFRs1-3, FGFRs 1-4 and PDGFRα) which are known to be upregulated in many tumours and tumour vasculature. In this report, we fused p700 to His-tagged, codon-optimised, carboxypeptidase G2 (CPG2). CPG2 is a bacterial enzyme used in ADEPT, which activates potent nitrogen-mustard pro-drugs by removal of an inhibitory glutamic acid residue. Recombinant CPG2-p700 was highly expressed in Escherichia coli and successfully purified by nickel affinity chromatography. Biolayer interferometry showed that CPG2-p700 had a 100-fold increase in binding affinity for VEGFR2 compared with CPG2 alone and retained its catalytic activity, as determined by methotrexate cleavage. In the presence of CPG2-p700, the ZD2676P pro-drug showed significant cytotoxicity for 4T1 cells compared with prodrug alone or CPG2 alone. p700 is, therefore, a potentially useful alternative to monoclonal antibodies for enzyme pro-drug therapy and could equally be used for effective delivery of other cytotoxic drugs to tumour tissue.

Specific Targeting of PEGylated Liposomal Doxorubicin (Doxil®) to Tumour Cells Using a Novel TIMP3 Peptide.

Doxorubicin is a cytotoxic anthracycline derivative that has been used as a chemotherapeutic in many different forms of human cancer with some success. However, doxorubicin treatment has several side-effects, the most serious of which is cardiomyopathy, that can be fatal. Doxorubicin encapsulation in PEGylated liposomes (Doxil®) has been shown to increase tumour localisation and decrease cardiotoxicity. Conversely, the stability of such liposomes also leads to increased circulation times and accumulation in the skin, resulting in palmar planter erythrodysesthesia, while also limiting release of the drug at the tumour site. Specific targeting of such liposomes to tumour cells has been attempted using various receptor-specific peptides and antibodies. However, targeting a single epitope limits the likely number of tumour targets and increases the risk of tumour resistance through mutation. In this report, Doxil® was coupled to peptide sequence p700 derived from tissue inhibitor of metalloproteinase 3. This Doxil® -P700 complex results in an approximately 100-fold increase in drug uptake, relative to Doxil® alone, by both mouse and human breast cancer cells and immortalised vascular cells resulting in an increase in cytotoxicity. Using p700 to target liposomes in this way may enable specific delivery of doxorubicin or other drugs to a broad range of cancers.