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The anti-cancer potential of Cyclopia species (honeybush) has been demonstrated in several models. The present study investigated the effects of aqueous and polyphenol-enriched (PE) extracts of C. subternata and C. genistoides, as well as mangiferin and hesperidin, on different cell growth parameters in human liver (HepG2) and colon (HT-29) cancer cells. Mangiferin and hesperidin were most abundant in C. genistoides and C. subternata, respectively. Cyclopia subternata extracts had the highest ferric-reducing antioxidant capacity. Following exposure of the cells to the extracts and compounds, cell viability, proliferation, and death (apoptosis and autophagy) were determined. Cyclopia subternata extracts reduced cell viability and inhibited cell proliferation the most, associated with depletion of ATP. In HepG2 cells, the PE extracts were less effective than the aqueous extracts in reducing cell viability but more effective in inhibiting cell proliferation. Despite disrupting cell growth, none of the extracts induced apoptosis. The aqueous extracts affected autophagy in both cancer cells. Disruption of mitochondrial membrane integrity by the different extracts, presumably via polyphenol/iron interactions, is postulated to be involved; however, mangiferin and hesperidin had no effect, suggesting that other polyphenols and/or complex interactions between compounds are likely responsible for the differential cytotoxic and/or cytoprotective effects of the extracts.

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Following population declines of the African savanna elephant (Loxodonta africana) across the African continent, the establishment of primary cell lines of endangered wildlife species is paramount for the preservation of their genetic resources. In addition, it allows molecular and functional studies on the cancer suppression mechanisms of elephants, which have previously been linked to a redundancy of tumor suppressor gene TP53. This methodology describes the establishment of primary elephant dermal fibroblast (EDF) cell lines from skin punch biopsy samples (diameter: ±4 mm) of African savanna elephants (n = 4, 14-35 years). The applied tissue collection technique is minimally invasive and paves the way for future remote biopsy darting. On average, the first explant outgrowth was observed after 15.75 ± 6.30 days. The average doubling time (Td) was 93.02 ± 16.94 h and 52.39 ± 0.46 h at passage 1 and 4, respectively. Metaphase spreads confirmed the diploid number of 56 chromosomes. The successful establishment of EDF cell lines allows for future elephant cell characterization studies and for research on the cancer resistance mechanisms of elephants, which can be harnessed for human cancer prevention and treatment and contributes to the conservation of their genetic material.

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The radiosensitivity of haematopoietic stem and progenitor cells (HSPCs) to neutron radiation remains largely underexplored, notwithstanding their potential role as target cells for radiation-induced leukemogenesis. New insights are required for radiation protection purposes, particularly for aviation, space missions, nuclear accidents and even particle therapy. In this study, HSPCs (CD34+CD38+ cells) were isolated from umbilical cord blood and irradiated with 60Co γ-rays (photons) and high energy p(66)/Be(40) neutrons. At 2 h post-irradiation, a significantly higher number of 1.28 ± 0.12 γ-H2AX foci/cell was observed after 0.5 Gy neutrons compared to 0.84 ± 0.14 foci/cell for photons, but this decreased to similar levels for both radiation qualities after 18 h. However, a significant difference in late apoptosis was observed with Annexin-V+/PI+ assay between photon and neutron irradiation at 18 h, 43.17 ± 6.10% versus 55.55 ± 4.87%, respectively. A significant increase in MN frequency was observed after both 0.5 and 1 Gy neutron irradiation compared to photons illustrating higher levels of neutron-induced cytogenetic damage, while there was no difference in the nuclear division index between both radiation qualities. The results point towards a higher induction of DNA damage after neutron irradiation in HSPCs followed by error-prone DNA repair, which contributes to genomic instability and a higher risk of leukemogenesis.

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The number of proton therapy facilities and the clinical usage of high energy proton beams for cancer treatment has substantially increased over the last decade. This is mainly due to the superior dose distribution of proton beams resulting in a reduction of side effects and a lower integral dose compared to conventional X-ray radiotherapy. More recently, the usage of metallic nanoparticles as radiosensitizers to enhance radiotherapy is receiving growing attention. While this strategy was originally intended for X-ray radiotherapy, there is currently a small number of experimental studies indicating promising results for proton therapy. However, most of these studies used low proton energies, which are less applicable to clinical practice; and very small gold nanoparticles (AuNPs). Therefore, this proof of principle study evaluates the radiosensitization effect of larger AuNPs in combination with a 200 MeV proton beam. CHO-K1 cells were exposed to a concentration of 10 µg/ml of 50 nm AuNPs for 4 hours before irradiation with a clinical proton beam at NRF iThemba LABS. AuNP internalization was confirmed by inductively coupled mass spectrometry and transmission electron microscopy, showing a random distribution of AuNPs throughout the cytoplasm of the cells and even some close localization to the nuclear membrane. The combined exposure to AuNPs and protons resulted in an increase in cell killing, which was 27.1% at 2 Gy and 43.8% at 6 Gy, compared to proton irradiation alone, illustrating the radiosensitizing potential of AuNPs. Additionally, cells were irradiated at different positions along the proton depth-dose curve to investigate the LET-dependence of AuNP radiosensitization. An increase in cytogenetic damage was observed at all depths for the combined treatment compared to protons alone, but no incremental increase with LET could be determined. In conclusion, this study confirms the potential of 50 nm AuNPs to increase the therapeutic efficacy of proton therapy.

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BACKGROUND: Colorectal malignant neoplasms is one of the leading causes of death in both men and women in the developed world and the incidence has recently increased markedly in South Africa. Studies have highlighted the beneficial effects of Amygdalin, a cyanogenic compound found in both peach and apricot kernels, in its ability to suppress the development of colon cancer. The focus of this study was to investigate the potential anti-proliferative properties of various apricot and peach kernels extractions from South Africa and China and to monitor alterations in cell cycle kinetics in colon cancer cells. METHODS: Studies were conducted on HT-29 colon cancer cells. The interactive role of three different kernel extractions on the modulation of cell proliferation, apoptosis and cell cycle progression was monitored over 24, 48 and 72 h periods. RESULTS: After 24 h, all extracts of the South African apricot kernels had a dose related bi-phasic proliferative effect on the HT-29 cells. It stimulated cell proliferation at the lowest and highest concentrations while at 500 µg/mL it inhibited cell proliferation. In contrast, after 72 h, the low concentration inhibited cell proliferation while the 500 µg/mL extracts stimulated cell proliferation. Morphological changes were observed in cells incubated with Chinese kernel extracts after 24 h and South African kernel treatment (1000 µg/mL) after 72 h. A possible intra-S-phase block after 24 and 48 h exposure to South African hydrophilic kernel extracts was observed. This transient block that is more concerned with tolerating and accommodating damage during replication rather than repairing it, could explain the initial anti-proliferative effects observed after 24 h exposure to the various Chinese kernel extract concentrations. CONCLUSION: Abrogation of the block by exhaustion of the cyanide production, most likely allowed the cells to resume the cell cycle and continue into mitosis, whereas low ATP levels caused by the presence of amygdalin in the kernels, can also cause the induction of pycnosis or necrosis. These results highlight the possible mechanisms of growth inhibition by amygdalin containing extracts and may contribute towards the development of dietary anti-cancer therapies.

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Widespread consumption of herbal teas has stimulated interest in their role as cancer preventive agents. The present investigation monitored the modulation of methylbenzylnitrosamine (MBN)-induced esophageal squamous cell carcinogenesis by rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia) herbal and Camellia sinensis teas in male F344 rats. The tumor multiplicity was significantly (P < 0.05) inhibited by unfermented honeybush (45.5%), green (50%), and black (36%) teas, while the other teas exhibited weaker effects (<30% inhibition). The mean total papilloma size was reduced by unfermented rooibos (87%), unfermented honeybush (94%), and fermented honeybush (74%) due to the absence of large papillomas (>10 mm(3)). Reduction of the mean total papilloma number correlated with the total polyphenol (TPP) (r = 0.79; P < 0.02) and flavanol/proanthocyanidin (FLAVA) (r = 0.89; P < 0.008) intake (mg/100 g body weight) of the teas and the FLAVA (r = 0.89; P < 0.04) and flavonol/flavones/xanthones (r = 0.99; P < 0.002) intake when considering only the herbal teas. A daily TPP intake threshold of 7 mg/100 g body weight existed below where no inhibition of papilloma development was observed. Fermentation of herbal teas reduced the inhibitory effects on papilloma development associated with a reduction in the polyphenolic constituents. The inhibitory effect of herbal teas on papilloma development is associated with different flavonoid subgroups and/or combination thereof.

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