Boswellia carterii oleoresin extracts induce caspase-mediated apoptosis and G1 cell cycle arrest in human leukaemia subtypes

Background: Leukemias are a common cancer in adults and children. While existing treatments are effective, they are associated with severe side-effects compounded by the emergence of drug resistance. This necessitates the need to develop new drugs and phytopharmaceuticals offer a largely untapped source. Oleoresins produced by plants in the genus Boswellia have been used for centuries in traditional medicine and recent work suggests they may exhibit anti-cancer activity. However, the underlying mechanisms remain unclear and most existing research focusses on Boswellia serrata; just one of many species in the Boswellia genus. To address these limitations, we elucidated the anti-cancer potential and associated mechanisms of action of Boswellia carterii. Methods: A methanolic solvent extraction method was optimised. The effect of methanolic extracts of B. carterii on leukaemia (K562, MOLT-4 and CCRF-CEM) and normal (PBMC) cell line viability was assessed using MTT assay and flow cytometry. Cell morphology, apoptosis (Annexin-V/propidium iodide), mitochondrial membrane potential (Rhodamine-123) and the cell cycle (propidium iodide) were evaluated using flow cytometry. Regulatory protein expression was quantified using Western Blot. Results: Methanolic extracts of B. carterii oleoresin reduced the viability of K562, MOLT-4 and CCRF-CEM cell lines with selectivity indexes of between 1.75 and 2.68. Extracts increased the proportion of cells in late apoptosis by 285.4% ± 51.6%. Mitochondrial membrane potential was decreased by 41% ± 2% and the expression of cleaved caspase-3, -7, and -9 was increased by 5.7, 3.3, and 1.5-fold respectively. Extracts increased the proportion of cells in subG1 and G1 phase by 867.8% ± 122.9% and 14.0 ± 5.5 and decreased those in S phase and G2/M by 63.4% ± 2.0% and 57.6% ± 5.3%. Expression of CDK2, CDK6, cyclin D1, and cyclin D3 were decreased by 2.8, 4.9, 3.9, and 2.5-fold. Conclusion: We are the first to report that methanolic extracts of B. carterii are selectively cytotoxic against three leukemia cell lines. Cytotoxic mechanisms likely include activation of the intrinsic apoptotic pathway and cell cycle arrest through downregulation of CDK2, CDK6, cyclin D1, and cyclin D3. Our findings suggest that B. carterii may be an important source of novel chemotherapeutic drugs and justifies further investigation.

An Ex vivo Apoptotic and Cytotoxic Effects of Frankincense on Oral Squamous Cell Carcinoma Cell Line

BACKGROUND: Oral squamous cell carcinoma is accounting for almost 90% of oropharyngeal cancer diagnoses. Natural herbal medicine can use as an alternative, or complementary, or adjunctive for cancer treatment. Frankincense and its combination with myrrh have anticancer effects on different cancer types. METHODS: In this research, aqueous and methanolic extracts of frankincense and the combination of aqueous extract of frankincense and myrrh were applied on tongue squamous cell carcinoma cell line to study their cytotoxic and apoptotic effect by the assessment of cell viability and cytotoxicity, caspase 3 and 8 activation, reactive oxygen species activity, mitochondrial membrane potential, morphological changes, and nuclear area factor measurements. RESULTS: The result showed that aqueous and methanolic extracts of frankincense have cytotoxic and apoptotic effects in a concentration-dependent manner with an IC50 value of 21.05 ± 1.27 μM for aqueous extract, 36.72 ± 2.07 μM for methanolic extract, and IC50 value of 1.31 ± 0.04 μM for combination of aqueous extract of frankincense and myrrh extract after 24 h. CONCLUSION: Different extracts of frankincense and the combination of aqueous extract of frankincense and myrrh extract exhibited cytotoxic and apoptotic effects by reducing the cell viability and activating caspases 3 and 8 causing intrinsic- and extrinsic-mediated apoptosis pathways activation with the involvement of oxidative stress that was conceivable with cytonuclear morphological alterations results.

Nanoencapsulation of Cordycepin Induces Switching from Necroptosis to Apoptosis in Human Oral Cancer Cells (HSC-4) Through Inhibition of Receptor-Interacting Serine/Threonine-Protein Kinase 3 (RIPK3) and Autophagy Modulation

Human oral squamous carcinoma is considered the most common oral cancer; it imposes multiple oral and dental consequences as a result of oral cancer treatment. We previously found that the nanoencapsulation of cordycepin (CS) could inhibit oral cancer cells. However, the mechanism of action was not understood. The aim of this study was to investigate the signaling pathway by which CS and encapsulated nanoparticles (NPs) activate the inhibition of cancer cell growth. We demonstrated that human oral cancer (HSC-4) cells underwent necroptosis when incubated with high concentrations of CS, but not when incubated with either low concentrations of CS or encapsulated CS NPs. High concentrations of CS-induced necroptosis of HSC-4 cells, demonstrated by a reduction in apoptotic ( BAX, Caspase-3, Caspase-8, and Caspase-9) and autophagic genes ( LC3, Atg5, and Atg12). However, low concentrations of CS significantly induced the expression of autophagic gene LC3. Interestingly, encapsulated CS NPs induced a significant increase in apoptotic genes ( P53, BAX, Caspase-3, Caspase-8, and Caspase-9), but a significant decrease in autophagic ( P62, Atg5, and Atg12) and necroptotic genes ( receptor-interacting serine/threonine-protein kinase 3 [RIPK3]) . We also found that encapsulated CS NPs enhanced the accumulation of cellular protein and decreased secreted supernatant protein levels. Moreover, encapsulated CS NPs had higher efficacy in terms of reactive oxygen species (ROS) generation-mediated inhibition of autophagy compared to nonencapsulated CS, suggesting that nanoencapsulation of CS can switch the program of HSC-4 cell death from necroptosis to apoptosis. In conclusion, HSC-4 cells have a defense strategy against CS-induced cell apoptosis, but this problem can be solved through the use of encapsulation combined with nanotechnology.

Cytotoxicity and apoptosis enhancement in breast and cervical cancer cells upon coadministration of mitomycin C and essential oils in nanoemulsion formulations

The present study aimed to solubilize the antineoplastic agent, mitomycin C (MMC), in two nanoemulsions (NEs) consisting of different essential oils (ginger (Gi) and frankincense (Fr)) in order to examine their anticancer activities on the HeLa cervical cancer cells and MCF-7 breast cancer cells. The two NEs-based Gi and Fr oil were produced by a high-pressure homogenization technique followed by solubilizing of the MMC in both NE formulas. The produced formulas were physically characterized by zetasizer and were applied on HeLa and MCF-7 cells at various concentrations for 24 h. The cytotoxicity assays were performed in vitro, using MTT assay, Coomassie blue staining for cellular morphology evaluation, and DAPI fluorescent staining for molecular cell death assessment. The average droplet diameters of the blank NEs have markedly increased and the charges of the droplets were significantly reversed when MMC was loaded. The potential cytotoxicity of the blank and combined formulas on HeLa and MCF-7 cells were dose-dependent and significantly greater than the toxicities of the free MMC. Among the MMC-loaded NE formulas, Fr-MMC has endured the nuclear apoptosis in HeLa cells at a lower concentration and reported the least % of florescence uptake compared to Gi-MMC. In contrast, the combination formula, Gi-MMC, has the strongest apoptotic effect on the MCF-7 cell line since it has the least % florescence uptake compared to the other formulations. Mixing MMC with Gi-NE and Fr-NE has considerably improved its cytotoxicity on the MCF-7 and HeLa cells.