Cytotoxicity of demalonyl thyrsiflorin A, a semisynthetic labdane-derived diterpenoid, to melanoma cells

Apoptosis induction of essential oils from Artemisia arborescens L. in human prostate cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Prostate cancer originates from cells inside a gland, which begin to grow out of control. In the world, prostate cancer is the most common cancer in the male population. New therapeutic strategies are needed for this tumor which still has a high mortality. A. arborescens leaves and aerial parts have various ethnopharmacological uses such as anti-spasmodic, and their decoctions were used to resolve urticaria, neuralgia and several lung diseases. Often this species has been also used to treat different inflammatory-related diseases such as cancer.

AIM OF THE STUDY

In a continuation of our research on essential oils from medicinal plants, we have selected, two essential oils from Artemisia arborescens L. (Compositae), an aromatic shrub widely used in traditional medicine. We evaluated their pro-apototic effect on androgen-sensitive (LNCaP) and androgen-insensitive (DU-145) human prostate cancer cells. In this study, we also evaluated the anti-Signal transducer and transcription factor 3 (STAT-3) activity of both essential oils in the human prostate cancer cell lines, and the treatment with Tumor necrosis factor (TNF)-Related Apoptosis (TRAIL).

MATERIALS AND METHODS

The cells were exposed to essential oils for 72 h and cell viability and cell membrane integrity were evaluated. Genomic DNA and the activity of caspase-3 was tested to confirm the cell death for apoptosis. Western blot analysis was employed to evaluate the expression of Bcl-2, Bax, cleaved caspase-3, cleaved caspase-9, Hsp70, STAT-3 and SOD proteins. Assays to evaluate reactive oxygen species (ROS) and GSH levels were also performed.

RESULTS

The results showed the capacity of two essential oils to activate an apoptotic process increasing the inhibition of Hsp70 and STAT-3 protein expression. In addition, our natural products sensitize LNCaP cells to Tumor necrosis factor (TNF)-Related Apoptosis (TRAIL)-induced apoptosis.

CONCLUSIONS

In summary, our study provides a further contribution to the hypothesis of the use of essential oils, from traditional medicinal plants, for the treatment of tumors, and suggests that the combination of our samples with other anti-prostate cancer therapies could be used to affect prostate cancer.

Functional Characterization of Three Diterpene Synthases Responsible for Tetracyclic Diterpene Biosynthesis in Scoparia dulcis

Scoparia dulcis produces unique biologically active diterpenoids such as scopadulcic acid B (SDB). They are biosynthesized from geranylgeranyl diphosphate (GGPP) via syn-copalyl diphosphate (syn-CPP) and scopadulanol as an important key intermediate. In this paper, we functionally characterized three diterpene synthases, SdCPS2, SdKSL1 and SdKSL2, from S. dulcis. The SdCPS2 catalyzed a cyclization reaction from GGPP to syn-CPP, and SdKSL1 did from syn-CPP to scopadulan-13α-ol. On the other hand, SdKSL2 was found to incorporate a non-sense mutation at 682. Therefore, we mutated the nucleotide residue from A to G in SdKSL2 to produce SdKSL2mut, and it was able to recover the catalytic function from syn-CPP to syn-aphidicol-16-ene, the precursor to scopadulin. From our results, SdCPS2 and SdKSL1 might be important key players for SDB biosynthesis in S. dulcis.

Physodic acid sensitizes LNCaP prostate cancer cells to TRAIL-induced apoptosis

In spite of the extensive research for developing new therapies, prostate cancer is still one of the major human diseases with poor prognosis and high mortality. Therefore, with the aim of identifying novel agents with antigrowth and pro-apoptotic activity on prostate cancer cells, in the present study, we evaluated the effect of lichen secondary metabolite physodic acid on cell growth in human prostate cancer cells. In addition, we tested the apoptotic activity of physodic acid on TRAIL-resistant LNCaP cells in combination with TRAIL. The cell viability was measured using MTT assay. LDH release, a marker of membrane breakdown, was also measured. For the detection of apoptosis, the evaluation of DNA fragmentation and caspase-3 activity assay were employed. The expression of proteins was detected by Western blot analysis. It was observed that physodic acid showed a dose-response relationship in the range of 12.5-50 μM concentrations in LNCaP and DU-145 cells, activating an apoptotic process. In addition, physodic acid sensitizes LNCaP cells to TRAIL-induced apoptosis. The combination of physodic acid with other anti-prostate cancer therapies could be considered a promising strategy that warrants further investigations.

In vitro cytotoxicity studies of smart pH-sensitive lamivudine-loaded CaAl-LDH magnetic nanoparticles against Mel-Rm and A-549 cancer cells

In this study, an effective nano-drug delivery system was prepared by the co-precipitation method via two steps; the preparation of Fe₃O₄ magnetic nanoparticles and its surface modification with layered double hydroxide (LDH) and loading lamivudine on this nanocarrier (Fe₃O₄@CaAl-LDH@Lamivudine). The developed nanoparticles (NPs) were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, Fourier-transformed infrared spectroscopy, vibrating-sample magnetometry, thermogravimetric analysis, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller. The prepared system demonstrated an average size of 130 nm. Also, the drug entrapment efficiency was estimated at ∼70%. In vitro, drug release investigations showed a controlled and pH-dependent lamivudine release over 300 min. The in vitro cytotoxic activity of Fe₃O₄@CaAl-LDH@Lamivudine NPs was explored against Mel-Rm and A-549 cancer cell lines in comparison with lamivudine and nanocarrier using lactate dehydrogenase colorimetric and MTT assay. The results of the MTT assay revealed that the Fe₃O₄@CaAl-LDH@Lamivudine NPs significantly inhibited the proliferation of Mel-Rm and A-549 cells in a dose-dependent manner. The influences of Fe₃O₄@CaAl-LDH@Lamivudine on the cancer cell lines by different therapeutic investigation illustrated the remarkable effect in comparison with free drug. Finally, the achieved consequences confirm the anticancer properties of Fe₃O₄@CaAl-LDH@Lamivudine and indicate that they may be a cost-effective substitute in the treatment of lung and skin cancer.Communicated by Ramaswamy H. Sarma.

Chamazulene-Rich Artemisia arborescens Essential Oils Affect the Cell Growth of Human Melanoma Cells

Artemisia arborescens is an aromatic shrub whose essential oils are considered a potential source of molecules with industrial and pharmaceutical interest. The chemical profile of A. arborescens essential oils (EOs) was shown to be quite variable and various chemotypes have been identified. In this study, we compared the EOs composition of A. arborescens leaves and flowers collected from four different locations in Sicily. The EOs were assayed for their antiproliferative activity against A375 human malignant melanoma cells, also testing cell viability and cell membrane integrity. The evaluation of DNA fragmentation and caspase-3 activity assay was employed for the detection of apoptosis. The expression of Bcl-2, Bax, cleaved caspase-9, PTEN (Phosphatase and tensin homolog), Hsp70 (Heat Shock Protein 70 kilodaltons) and SOD (superoxide dismutase) proteins was evaluated by Western blot analysis. The levels of ROS and GSH were also analyzed. Results show that EOs presented significant differences in their composition, yield, and cytotoxic activity depending on the collection site. The chamazulene/camphor-rich EOs from plants collected in Acqua Calda (Lipari) resulted particularly active on melanoma cancer cells (IC₅₀ values of 6.7 and 4.5 µg/mL), being able to trigger apoptotic death probably interfering with endogenous defense mechanisms. These oils may be considered as a natural resource of chamazulene, containing this compound up to 63%.

Oregano (Origanum vulgare L.) essential oil provides anti-inflammatory activity and facilitates wound healing in a human keratinocytes cell model

Skin acts as a protective barrier between the body and the external environment. Skin wounds are a common inflammatory disorder for the solution of which plants and essential oils have been applied as a medical option for centuries. Origanum vulgare essential oil (OEO) is largely used in folk medicine, but its molecular mechanisms of action are not fully known. In this study, we evaluated the anti-inflammatory/antioxidant activity as well as wound healing capacity of a well-characterized OEO on human keratinocytes NCTC 2544 treated with interferon-gamma (IFN-γ) and histamine (H) or subjected to a scratch test. The expression of pro-inflammatory mediators such as reactive oxygen species (ROS), inter-cellular adhesion molecule (ICAM)-1, inducible nitric oxide synthase (iNOS), and cyclooxygenase (COX)-2 were verified. The DNA damage was shown by the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-OHdG) and activation of proliferating cell nuclear antigen (PCNA). Moreover, the abnormal modification of extracellular matrix components (ECM) was examined by determining matrix metalloproteinase (MMP)-1, and -12. Compared to untreated control, OEO showed efficacy in supporting and enhancing the cell motility. In IFN-γ and H treated cells, OEO displayed a significant reduction of ROS, ICAM-1, iNOS, COX-2, 8-OHdG, MMP-1, and MMP-12. OEO proved useful to treat inflammation and support cell motility during wound healing.

Moscatilin, a bibenzyl derivative from the orchid Dendrobium loddigesii, induces apoptosis in melanoma cells

The use of orchids in herbal medicine has a very long history. Dendrobium species are known to produce a variety of secondary metabolites such as phenanthrens, bibenzyls, fluorenones and sesquiterpenes, and alkaloids and are responsible for their wide variety of medicinal properties. For decades, bibenzyls, which are the main bioactive components derived from Dendrobium species, have been subjected to extensive investigation as likely candidates for cancer treatment. The present study was undertaken to investigate the effect of moscatilin, a bibenzyl derivative from the orchid Dendrobium loddigesii on human melanoma cells. In A375 cells compound moscatilin showed a clear dose-response relationship in the range of 6.25-50 μM concentrations. In addition, we demonstrated an apoptotic response after treatment of cancer cells with this bibenzyl compound at 6.25 and 12.5 μM concentrations that probably involves PTEN activity, inhibition of Hsp70 expression and reactive oxygen species production. Alternatively, the inhibition of the caspase cascade at higher concentrations, 25 and 50 μM, correlated with additional reactive oxygen species increase, probably switched the mode of moscatilin-induced cell death from apoptosis to necrosis.

Isocordoin analogues promote apoptosis in human melanoma cells via Hsp70

Isocordin 1 and a series of 4-oxyalkyl-isocordoin analogues 2-8 were evaluated for their cytotoxicity effect against human melanoma cells (A2058). Analogues 4, 5, and 6 showed a higher inhibitory activity with IC₅₀ values of 12.91 ± 0.031, 24.88 ± 0.013, and 11.62 ± 0.017, respectively. These analogues, 4, 5, and 6, also induced an apoptotic response at 12.5- and 25-μM concentrations. They inhibited the expression of antiapoptotic proteins Bcl-2 and Hsp70, a critical factor that promotes tumour cell survival. In contrast, Bax and caspase-9 expression, and caspase-3 enzyme resulted activated. These results were correlated to a DNA fragmentation typical of apoptosis and an increase of intracellular reactive oxygen species (ROS) levels. Alternatively, at higher concentration (50 μM), when the capacity of the cells to sustain Hsp70 synthesis is reduced, our results seem to indicate that necrosis was induced by a further increase in ROS production. Therefore, the central finding in the present study is that these molecules downregulates Hsp70 expression. Altogether, these results suggest that 4-oxyalkyl-isocordoin analogues 4, 5, and 6 deserve to be deeply investigated for a possible application as Hsp70 inhibitor in the management of melanoma.

Blue Light Induces Down-Regulation of Aquaporin 1, 3, and 9 in Human Keratinocytes

The development in digital screen technology has exponentially increased in the last decades, and many of today’s electronic devices use light-emitting diode (LED) technology producing very strong blue light (BL) waves. Long-term exposure at LED-BL seems to have an implication in the dehydration of the epidermis, in the alterations of shape and number of the keratinocytes, and in the aging of the skin. Aquaporins (AQPs) are water membrane channels that permeate both water and glycerol and play an important role in the hydration of epidermis, as well as in proliferation and differentiation of keratinocytes. Thus, we have hypothesized that AQPs could be involved in the aging of the skin exposed to LED-BL. Therefore, we have examined the expression of AQPs in human keratinocytes exposed to LED-BL at dose of 45 J/cm², used as an in vitro model to produce the general features of photo aging of the skin. The aim was to verify if LED-BL induces changes of the basal levels of AQPs. The keratinocytes exposure to LED-BL produced an increase of reactive oxygen species (ROS), an activation of 8-hydroxy-2’-deoxyguanosine (8-OHdG), an alteration of proliferating cell nuclear antigen (PCNA), and a down-regulation of AQP1, 3 and 9. These findings are preliminary evidences that may be used as starting points for further investigations about the mechanistic involvement of AQP1, 3, and 9 in LED-BL-induced skin aging.

Hydroxytyrosol from olive fruits prevents blue-light-induced damage in human keratinocytes and fibroblasts

Skin aging is a complex biological process influenced by a combination of endogenous or intrinsic and exogenous or extrinsic factors due to environmental damage. The primary environmental factor that causes human skin aging is the ultraviolet irradiation from the sun. Recently, it was established that the long-term exposure to light-emitting-diode-generated blue light (LED-BL) from electronic devices seems to have a relevant implication in the molecular mechanisms of premature photoaging. BL irradiation induces changes in the synthesis of various skin structures through DNA damage and overproduction of reactive oxygen species (ROS), matrix metalloproteinase-1 and -12, which are responsible for the loss of the main components of the extracellular matrix of skin like collagen type I and elastin. In the current study, using human keratinocytes and fibroblasts exposed to specific LED-BL radiation doses (45 and 15 J/cm ² ), we produced an in vitro model of skin photoaging. We verified that, compared with untreated controls, the treatment with LED-BL irradiation results in the alteration of metalloprotease-1 (collagenase), metalloprotease-12 (elastase), 8-dihydroxy-2'-deoxyguanosine, proliferating cell nuclear antigen, and collagen type I. Moreover, we showed that the photoaging prevention is possible via the use of hydroxytyrosol extracted from olive fruits, well known for antioxidant properties. Our results demonstrated that hydroxytyrosol protects keratinocytes and fibroblasts from LED-BL-induced damage. Thus, hydroxytyrosol might be proposed as an encouraging candidate for the prevention of BL-induced premature photoaging.