Porphyrin/Chlorin Derivatives as Promising Molecules for Therapy of Colorectal Cancer

Colorectal cancer (CRC) is a leading cause of cancer-related death. The demand for new therapeutic approaches has increased attention paid toward therapies with high targeting efficiency, improved selectivity and few side effects. Porphyrins are powerful molecules with exceptional properties and multifunctional uses, and their special affinity to cancer cells makes them the ligands par excellence for anticancer drugs. Porphyrin derivatives are used as the most important photosensitizers (PSs) for photodynamic therapy (PDT), which is a promising approach for anticancer treatment. Nevertheless, the lack of solubility and selectivity of the large majority of these macrocycles led to the development of different photosensitizer complexes. In addition, targeting agents or nanoparticles were used to increase the efficiency of these macrocycles for PDT applications. On the other hand, gold tetrapyrrolic macrocycles alone showed very interesting chemotherapeutic activity without PDT. In this review, we discuss the most important porphyrin derivatives, alone or associated with other drugs, which have been found effective against CRC, as we describe their modifications and developments through substitutions and delivery systems.

Photo-Uncaging of a Microtubule-Targeted Rigidin Analogue in Hypoxic Cancer Cells and in a Xenograft Mouse Model

Marine alkaloid rigidins are cytotoxic compounds known to kill cancer cells at nanomolar concentrations by targeting the microtubule network. Here, a rigidin analogue containing a thioether group was "caged" by coordination of its thioether group to a photosensitive ruthenium complex. In the dark, the coordinated ruthenium fragment prevented the rigidin analogue from inhibiting tubulin polymerization and reduced its toxicity in 2D cancer cell line monolayers, 3D lung cancer tumor spheroids (A549), and a lung cancer tumor xenograft (A549) in nude mice. Photochemical activation of the prodrug upon green light irradiation led to the photosubstitution of the thioether ligand by water, thereby releasing the free rigidin analogue capable of inhibiting the polymerization of tubulin. In cancer cells, such photorelease was accompanied by a drastic reduction of cell growth, not only when the cells were grown in normoxia (21% O₂) but also remarkably in hypoxic conditions (1% O₂). In vivo, low toxicity was observed at a dose of 1 mg·kg^-1 when the compound was injected intraperitoneally, and light activation of the compound in the tumor led to 30% tumor volume reduction, which represents the first demonstration of the safety and efficacy of ruthenium-based photoactivated chemotherapy compounds in a tumor xenograft.

Chemical Composition and Antioxidant, Anti-Inflammatory, and Antiproliferative Activities of Lebanese Ephedra Campylopoda Plant

Background

This study aimed to identify the phytochemical content and evaluate the antioxidant, anti-inflammatory, and antiproliferative capacities of various solvent extracts of Ephedra campylopoda stems.

Material/Methods

Fresh stems were suspended in 3 different solvent systems, including distilled water, ethanol, and methanol. The chemical composition was determined using high-performance liquid chromatography (HPLC), and the content of essential oil of this plant species was determined by gas chromatography (GC) coupled with mass spectrometry (MS). Antioxidant activity was determined using DPPH radical scavenging and Fe²⁺-chelating activity assays. Anti-inflammatory capacity was estimated by both evaluating RAW 264.7 murine macrophage cells-mediated secretion of PGE₂ using ELISA technique, and quantifying the mRNA level of the pro-inflammatory cytokines (IL-α, IL-β and IL-6), chemokines (CCL3 and CCL4), and inflammation-inducible COX-2 and iNOS enzymes using quantitative real-time PCR (qRT-PCR). The antiproliferative potential was determined using the XTT viability assay.

Results

Our results showed that the alcoholic extracts were better than the aqueous one in terms of their chemical composition. In parallel, the alcoholic extracts showed more potent antioxidant, anti-inflammatory, and antiproliferative capacities than aqueous extract.

Conclusions

Our observations suggest that Ephedra campylopoda plant could be a promising resource of natural products with antioxidant, anti-inflammatory and antiproliferative capacities.

Chemical Composition, Antioxidant, Anti-Inflammatory, and Antiproliferative Activities of the Plant Lebanese Crataegus Azarolus L

Background

In the present study, phytochemical screening, antioxidant, anti-inflammatory, and antiproliferative capacities of 3 extracts from leaves of Lebanese Crataegus azarolus L. were evaluated.

Material/Methods

Fresh leaves were dissolved in 3 different solvents: distilled water, ethanol, and methanol. The chemical composition was determined using high-performance liquid chromatography (HPLC) and the content of essential oil of this plant was examined by gas chromatography (GC) coupled with mass spectrometry (MS). The antioxidant potential was evaluated using DPPH radical scavenging and Fe²⁺ chelating activity assays. Anti-inflammatory effect was investigated by measuring the secreted amounts of the proinflammatory mediator PGE₂ using ELISA technique, as well as by assaying the mRNA levels of the proinflammatory cytokines (IL-α, IL-β, and Il-6), chemokines (CCL3 and CCL4) and inflammation-sensitive COX2 and iNOS enzymes using quantitative real-time PCR (qRT-PCR). The antiproliferative effect was evaluated using the XTT viability assay.

Results

The obtained results show that alcohol (methanol and ethanol) extracts were rich in bioactive molecules with medical relevance and exerted substantial antioxidant, anti-inflammatory, and antiproliferative capacities. On the other hand, aqueous extract contained fewer chemical components and exhibited less therapeutic efficiency.

Conclusions

Our observations indicate that Crataegus azarolus L. could be used for treating diseases related to oxidative stress, inflammatory reactions, and uncontrolled cell growth.

Delivery of tanshinone IIA and α-mangostin from gold/PEI/cyclodextrin nanoparticle platform designed for prostate cancer chemotherapy

A new anti-cancer drug delivery system, based on gold nanoparticles, has been designed for hydrophobic active compounds. The system is a conjugate of gold/polyethyleneimine (AuNPs/PEI) nanoparticles and sulphated β-cyclodextrin (CD). Anionic cyclodextrin was attached to the positively charged AuNPs/PEI nanoparticles by ionic bonds. Tanshinone IIA and α-mangostin were extracted, purified and encapsulated into the AuNPs/PEI/CD nanoparticles. In vitro preliminary cell viability assays against prostate cancer cell lines PC-3 and DU145 showed that encapsulation resulted in increased cytotoxicity.

Novel methylsulfonyl chalcones as potential antiproliferative drugs for human prostate cancer: involvement of the intrinsic pathway of apoptosis

Limited success has been achieved in extending the survival of patients with metastatic and hormone-refractory prostate cancer (HRPC). There is a strong need for novel agents in the treatment and prevention of HRPC. In the present study, the apoptotic mechanism of action of RG003 (2'-hydroxy-4-methylsulfonylchalcone) and RG005 (4'-chloro-2'-hydroxy-4-methylsulfonylchalcone) in association with intracellular signalling pathways was investigated in the hormone-independent prostate carcinoma cells PC-3 and DU145. We showed that these compounds induced apoptosis through the intrinsic pathway but not through the extrinsic one. We showed that synthetic chalcones induced an activation of caspase-9 but not caspase-8 in PC-3 cells. Even if both chalcones induced apoptosis in PC-3 cells, a dominant effect of RG003 treatment was observed resulting in a disruption of ∆ψm, caspase-9 and caspase-3 activation, PARP cleavage and DNA fragmentation. Furthermore, in regard to our results, it is clear that the simultaneous inhibition of Akt and NF-κB signalling can significantly contribute to the anticancer effects of RG003 and RG005 in PC-3 prostate cancer cells. NF-κB inhibition was correlated with the reduction of COX-2 expression and induction of apoptosis. Our results clearly indicate for the first time that RG003 and RG005 exert their potent anti‑proliferative and pro-apoptotic effects through the modulation of Akt/NF-κB/COX-2 signal transduction pathways in PC-3 prostate cancer cells with a dominant effect for RG003.

Integrin α5β1 plays a critical role in resistance to temozolomide by interfering with the p53 pathway in high-grade glioma

Integrins play a role in the resistance of advanced cancers to radiotherapy and chemotherapy. In this study, we show that high expression of the α5 integrin subunit compromises temozolomide-induced tumor suppressor p53 activity in human glioblastoma cells. We found that depletion of the α5 integrin subunit increased p53 activity and temozolomide sensitivity. However, when cells were treated with the p53 activator nutlin-3a, the protective effect of α5 integrin on p53 activation and cell survival was lost. In a functional p53 background, nutlin-3a downregulated the α5 integrin subunit, thereby increasing the cytotoxic effect of temozolomide. Clinically, α5β1 integrin expression was associated with a more aggressive phenotype in brain tumors, and high α5 integrin gene expression was associated with decreased survival of patients with high-grade glioma. Taken together, our findings indicate that negative cross-talk between α5β1 integrin and p53 supports glioma resistance to temozolomide, providing preclinical proof-of-concept that α5β1 integrin represents a therapeutic target for high-grade brain tumors. Direct activation of p53 may remain a therapeutic option in the subset of patients with high-grade gliomas that express both functional p53 and a high level of α5β1 integrin.

Antiproliferative effect of extracts from Aristolochia baetica and Origanum compactum on human breast cancer cell line MCF-7

Aristolochia baetica L. (Aristolochiaceae) and Origanum compactum Benth. (Lamiaceae) are native plants of Morocco used in traditional medicine. In order to systematically evaluate their potential activity on human breast cancer, four different polarity extracts from each plant were assessed in vitro for their antiproliferative effect on MCF-7 cells. As a result, several extracts of those plants showed potent cell proliferation inhibition on MCF-7 cells. Chloroform extract of A. baetica (IC50: 216.06 +/- 15 microg/mL) and ethyl acetate of O. compactum (IC50: 279.51 +/- 16 microg/mL) were the most active. Thin layer chromatography examination of the bioactive extracts of A. baetica and O. compactum showed the presence of aristolochic acid and betulinic acid, respectively. These results call for further studies of these extracts.

Roots of Daphne gnidium L. inhibit cell proliferation and induce apoptosis in the human breast cancer cell line MCF-7

Daphne gnidium L. is a well-known Moroccan plant with cancer-related ethnobotanical use. In order to systematically evaluate its potential activity in breast cancer, four extracts from this plant of different polarity were tested for their antiproliferative effects on MCF-7 cells. The second aspect of this study related to understanding the nature and mechanism of the antiproliferative effect. Results from a viability assay showed the potent antiproliferative capacity of the hexane (IC(50)-48 h: 630 +/- 16 microg/ml), dichloromethane (IC(50)-48 h: 112 +/- 7 microg/ml) and ethyl acetate extracts (IC(50)-48 h: 263 +/- 9 microg/ml). On the other hand the methanol extract was inactive. LDH test revealed the cytotoxicity of the hexane extract as opposed to two others. The characterization of the ethyl acetate extract showed its dose-dependent pro-apoptotic effect. Surprisingly, we observed that activation of the inducible cyclooxygenase-2 followed the kinetics of apoptosis development. On the other hand, the dichloromethane extract showed a distinct effect on COX-2 activity as a function of the used dose. A low dose seemed to inhibit COX-2 activity whereas a high dose seemed to increase it. These findings suggest that Daphne gnidium L. might be of potential chemopreventive interest. Other studies are in hand to isolate the active agents responsible for the antiproliferative effect.

Inhibition of human rheumatoid arthritis synovial cell survival by hecogenin and tigogenin is associated with increased apoptosis, p38 mitogen-activated protein kinase activity and upregulation of cyclooxygenase-2

We conducted our study to assess the antiproliferative and proapoptotic potential of hecogenin and tigogenin, two saponins which are structurally similar to diosgenin. We particularly focused our attention on mitogen-activated protein kinase (MAPK) activation in relation to apoptosis but also with the COX-2 expression and activity. Rheumatoid arthritis (RA) synoviocytes were isolated from fresh synovial biopsies obtained from five RA patients undergoing hip arthroplasty. Measurement of cell proliferation was determined using the MTT assay. Apoptosis was evaluated by studying caspase-8, caspase-9 and caspase-3 activities but also by quantification of DNA fragmentation. Quantification of human phospho-MAPKs was realized by ELISA. COX-2 expression was demonstrated by Western blot analysis and COX-2 activity by assay of endogenous prostaglandin E2 (PGE2) production. Tigogenin was more effective than hecogenin in inducing apoptosis in human RA fibroblast-like synoviocytes (FLS) which was caspase dependent but poly(ADP-ribose) polymerase independent and characterized by DNA fragmentation. Our results demonstrated hecogenin- and tigogenin-induced apoptosis through activation of p38 without affecting the JNK and ERK pathways. Indeed, pretreatment with a p38 inhibitor decreased saponin-induced apoptosis with a significant decrease in DNA fragmentation. Furthermore, the rate of apoptosis induced by hecogenin or tigogenin was associated with overexpression of COX-2 correlated with overproduction of endogenous PGE2. These new results provide strong evidence that a family of structurally similar plant steroids is capable of inducing apoptosis in human RA FLS with different rates and different signalling pathways. This study also confirms the discussed appearance of the downregulation or upregulation of COX-2 in cell apoptosis as a function of cell type.

MAP kinase subtypes and Akt regulate diosgenin-induced apoptosis of rheumatoid synovial cells in association with COX-2 expression and prostanoid production

In the present study, we investigated the signalling pathways involved in diosgenin-induced apoptosis in human rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) in vitro with particular interest on Akt and MAPKs activation in relation to arachidonic acid metabolism via COX-2 pathway. MAPK activation was measured by ELISA quantification in diosgenin-treated human RA FLS. Expression of Akt and phospho-Akt was analyzed by Western blot analysis. Nuclear factor-kappaB (NF-kappaB) translocation was evaluated by electromobility shift assay. The prostanoid production (COX-2 activity) was measured by quantitative ELISA. Diosgenin-induced apoptosis in the presence of MAPK or Akt inhibitors was detected by a quantitative determination of DNA fragmentation. Treatment of human RA FLS with 40 microM diosgenin caused an activation of p38 and JNK and an inhibition of ERK phosphorylation. Akt and NF-kappaB are potentially required for diosgenin-induced apoptosis in human RA FLS because 40 microM diosgenin abrogated Akt phosphorylation which correlated with an inhibition of NF-kappaB nuclear translocation. SB203580 and SP600125 (p38 and JNK inhibitors) reduced diosgenin-induced DNA fragmentation whereas U0126 and LY294002 (MEK and PI3 kinase/Akt inhibitors) caused an amplification of proapoptotic effect of diosgenin. Diosgenin increased COX-2 activity resulting in PGE2 and 6-keto-PGF1alpha overproduction in human RA FLS. All MAPK inhibitors markedly reduced diosgenin-induced PGE2 and 6-keto-PGF1alpha synthesis except for SP600125 on 6-keto-PGF1alpha production. These results provide, for the first time, strong evidence that a combined association implicating a MEK inhibitor (U0126) and diosgenin is the most effective in inducing very strong apoptosis with down-regulation of COX-2 expression and activity in human RA FLS.

Low dose leflunomide activates PI3K/Akt signalling in erythroleukemia cells and reduces apoptosis induced by anticancer agents

Rheumatoid arthritis (RA) is characterized by persistent joint synovial tissue inflammation. Leflunomide is an immunomodulatory agent that has been approved for treatment of active RA. In the past few years, uses other than RA treatment have appeared. Leflunomide has been reported to show antitumor potential through inhibition of cancer cell proliferation. We thus tested the antiproliferative potential of leflunomide on HEL and K562 erythroleukemia cells. The findings summarized in this report demonstrate for the first time that low dose leflunomide prolonged survival and reduced apoptosis induced by several anticancer agents in erythroleukemia cells. We showed that in treated cells, leflunomide reduced the signalling pathways involved in promoting apoptosis by reducing p38 MAPK and JNK basal activity. On the other hand, leflunomide transiently activated the ERK signalling pathway and induced a sustained activation of Akt. We also showed that leflunomide reduced caspase-3 activity and DNA fragmentation induced by anticancer agents. By using an inhibitory strategy, we showed that inhibition of Akt activation but not ERK abolished the protective effect of leflunomide. Thus our findings suggested that leflunomide reduced apoptosis induced by anticancer agents through PI3K/Akt signalling activation.

Role of MAPKs and NF-kappaB in diosgenin-induced megakaryocytic differentiation and subsequent apoptosis in HEL cells

Megakaryocytopoiesis is characterized by progressive polyploidization and acquisition of megakaryo-cytic markers. MAPK pathways play a key role during megakaryocytic differentiation of megakaryocyte precursors or leukemic cells. Apoptosis is the physiological fate of normal megakaryocyte after differentiation and maturation. The aim of this study was to investigate the signaling pathways involved in diosgenin-induced differentiation and the fate of diosgenin-differentiated HEL cells. The present report shows that diosgenin induced megakaryocytic differentiation of HEL cells through a combined activation of ERK and inhibition of the p38 MAPK pathways. Inhibition of ERK activation by a MEK inhibitor abrogated diosgenin-induced differentiation. Afterwards, differentiated cells showed a marked inhibition of expression of survival factors NF-kappaB, Akt and Bcl-xL and activation of caspase-3 together with PARP cleavage leading to apoptotic death of diosgenin-differentiated cells.

Diosgenin, a plant steroid, induces apoptosis in COX-2 deficient K562 cells with activation of the p38 MAP kinase signalling and inhibition of NF-kappaB binding

Diosgenin is a steroidal sapogenin with antitumor properties. We previously showed that diosgenin induced apoptosis in human erythroleukemia (HEL) cells. In order to elucidate the mechanism of its apoptotic activity, we investigated the effect of diosgenin on nuclear factor-kappaB (NF-kappaB) binding and on three groups of human mitogen-activated protein kinases (MAPKs) in relation to diosgenin-induced apoptosis in different erythroleukemia cell lines (K562 and HEL). Our results showed that diosgenin decreased DNA binding of NF-kappaB in K562 and HEL cells after 48-h diosgenin treatment. This inhibition of NF-kappaB binding was correlated with strong apoptosis in both erythroleukemia cell lines. Diosgenin-induced apoptosis was associated with cyclo-oxygenase-2 (COX-2) up-regulation in HEL cells but not in K562 cells which are COX-2 deficient. Furthermore, diosgenin inhibited extracellular signal-regulated kinase (ERK) activation only in HEL cells. However, diosgenin activated p38 MAPK in both cell lines and activated c-jun NH2-terminal kinases (JNKs) only in HEL cells. Pre-treatment with a selective p38 inhibitor inhibited diosgenin-induced DNA fragmentation in K562 cells. For the first time, our results suggest that inhibition of NF-kappaB nuclear binding and p38 MAPK activation are involved in the diosgenin-mediated signal cascades in K562 cells for inducing/regulating DNA fragmentation.

Diosgenin induces cell cycle arrest and apoptosis in HEL cells with increase in intracellular calcium level, activation of cPLA2 and COX-2 overexpression

Many natural components of plant extracts are studied for their beneficial effects for health and particularly on carcinogenesis chemoprevention. In the present study, we investigated the effects of diosgenin on erythroleukemia HEL cells. Our results demonstrated that diosgenin induced G2/M arrest of cell cycle progression through p21 up-regulation in a p53-independent pathway and strong induction of apoptosis in HEL cells. Apoptosis induction was accompanied by an increase in Bax/Bcl-2 ratio, PARP cleavage and DNA fragmentation. Moreover, we showed for the first time that diosgenin provoked a collapse of mitochondrial membrane potential with an increase in intracellular calcium levels. It is well known that [Ca2+]i increase is one of the major activators of cytosolic PLA2. In our study, we demonstrated that diosgenin treatment induced cPLA2 activation through translocation to the cellular membrane. Moreover, arachidonic acid metabolism activation led to cyclooxygenase-2 (COX-2) but not lipoxygenase overexpression. Surprisingly, we observed a COX-2 up-regulation associated with apoptosis induction by diosgenin. These findings suggest that diosgenin has a potential chemopreventive effect; future studies should evaluate the mechanism of COX-2 activation during diosgenin-induced apoptosis in cancer cell lines.