Bioactivity-guided isolation of cytotoxic constituents from stem–bark of Premna tomentosa

A bioassay-guided fractionation and chemical investigation of the stem bark of Premna tomentosa resulted in the isolation and characterization of four new icetexane diterpenes (1–4), along with the known compounds coniferaldehyde (5), syringaldehyde (6), lupeol (7), betulin (8), and 2-(4-methoxyphenyl)-2-butanone (9). Their structures were established on the basis of extensive spectroscopic (IR, MS, 2D NMR) data analysis and by comparison with the spectroscopic data reported in the literature. The new compounds exhibited diverse functionalities on a common icetexane diterpene skeleton. In addition, cytotoxic activities of the icetexanes (1–3) were evaluated by determining their inhibitory effects on the human cancer cell lines (MCF-7, HT-29, Hep-G2, A-431, and A-549). Compounds 1 and 3 showed selective inhibitory activity against MCF-7 (15.96 μg/mL and 15.84 μg/mL) and HT-29 cell lines (16.21 μg/mL and 14.57 μg/mL), respectively.     

Do cancer cells in human and meristematic cells in plant exhibit similar responses toward plant extracts with cytotoxic activities?

We examined the effect of water extracts of Persea americana fruit, and of the leaves of Tabernamontana divericata, Nerium oleander and Annona cherimolia (positive control) on Vicia faba root cells. We had confirmed in our previously published data the cytotoxicity of these plant extracts on four human cancer cell lines: liver (HepG-2), lung (A549), colon (HT-29) and breast (MCF-7). Vicia faba roots were soaked in plant extracts at dilutions of 100, 1,250, 2,500, 5,000, 10,000, 20,000 ppm for 4 and 24 h. All treatments resulted in a significant reduction in the mitotic index in a dose dependant manner. Root cells treated with T. divericata, N. oleander and A. cherimolia exhibited a decrease in prophase cell percentage, increase in micronuclei and chromosomal abnormalities as concentration increased. The P. americana treatment showed the highest cytotoxic effect on cancer cells, prophase cell percentage increased linearly with the applied concentration and no micronuclei were detected. This study shows that root tip assay of beans can be used in initial screening for new plant extracts to validate their use as candidates for containing active cytotoxic agents against malignant cells. This will greatly help in exploring new plant extracts as drugs for cancer treatment.     

Antiproliferative and Apoptosis Inducing Effects of Non-Polar Fractions from Lawsonia inermis L. in Cervical (HeLa) Cancer Cells

Two non-polar fractions viz. hexane (Hex-LI) and chloroform fraction (CHCl₃-LI) of Lawsonia inermis were studied for their antiproliferative potential in various cancer cell lines viz. HeLa, MCF-7, A549 and C6 glioma cells. Both the fractions showed more than 60 % of growth inhibition in all the tested cell lines at highest tested concentration. In clonogenic assay, different concentrations of Hex-LI and CHCl₃-LI decreased the number and size of colonies as compared to control in HeLa cells. The apoptotic effects as nuclear condensation, fragmentation were visualized with Hoechst-33342 staining of HeLa cells using confocal microscope. Both fractions induced apoptotic cell death in human cervical carcinoma (HeLa) cells as evident from flow cytometric analysis carried out using Annexin V-FITC and propidium iodide dyes. CHCl₃-LI treated cells significantly induced apoptosis (25.43 %) in comparison to control. Results from Neutral Comet assay demonstrated that both fractions induced double stranded breaks (DSB’s) in HeLa cells. Our data indicated that Hex-LI and CHCl₃-LI treated cells showed significant increase of 32.2 and 18.56 % reactive oxygen species (ROS) levels in DCFH-DA assay respectively. Further, experimental studies to decipher exact pathway via which these fractions induce cell death are in progress.     

In-Vitro and in-Silico characterization of Sophora interrupta plant extract as an anticancer activity

Sophora interrupta belongs to the family of Fabaceae and the species in this genus have a diverse medicinal importance as a folk medicine for preventing many ailments including cancer. In order to evaluate the anticancer activity of S.interrupta, we have performed in vitro anti-oxidant, anti-inflammatory, anti-proliferative, and cell based anticancer activity in MCF-7 and PC-3 cell lines. Secondary metabolites of S.interrupta were used to identify anticancer compounds using Open Eye software. The antioxidant activity of the S.interrupta root ethylacetate (SEA) extract at 100 µg/ml is equal to that of ascorbic acid at 50 µg/ml. The antiinflammatory activity of SEA is half of that of diclofenac at 50 µg/ml. Anticancer activity was detected by measuring the mitochondrial dehydrogenase activity (MTT assay). The half maximal inhibitory concentrations (IC₅₀) for MCF-7 and PC-3 cell lines are 250 and 700 µg/ml respectively. This was supported by the morphological changes such as membrane blebbing, cell detachment and rounded cell morphology when compared to the parental cells. In addition, we observed few green cells (live) over red cells (dead) based on the uptake of acridine orange and ethidium bromide dyes. Kaempferol-3-O-b-D-glucopyranoside, a Secondary metabolite of S.interrupta form 6 hydrogen bond interactions with Arg 202, Gln 207, Gly 227, Gly 229, Thr 231 and Ala 232 human DEAD box RNA helicase, DDX3 protein and is equivalent to crystal structure of adenosine mono phosphate to DDX3. Overall, it suggests that the SEA extract has anticancer compounds, and it can be used to enhance death receptor mediated cancer cell death.     

Effects of Lonomia obliqua caterpillar venom upon the proliferation and viability of cell lines

Many active principles produced by animals, plants and microorganisms have been employed in the development of new drugs for the treatment of human diseases. Among animals known to produce pharmacologically active molecules that interfere in human cell physiology, the caterpillar Lonomia obliqua has become the focus of toxicological studies due to recent findings about its venom constituents. The objective of this study was to investigate the effects of L. obliqua venom upon the viability and the proliferation of different cell lineages and to propose mechanisms for the herein observed induction of cell proliferation in glioma cell lines. MTT analyses indicate that L. obliqua venom increases the viability of tumor cell lines U138-MG and HT-29; on the other hand, it inhibits the viability of V-79 nontumor cells. Cell count based on the trypan blue exclusion method suggests a proliferating activity of the venom upon U138-MG cells. Exposure of U138-MG to crude venom extract led to a decrease in the production of nitric oxide, and activation of the cAMP signaling pathway inhibited the effects of the venom, indicating that these mechanisms may influence cell proliferation triggered by the venom. Despite the proliferative effects of crude venom on U138-MG and HT-29 cell cultures, a protein purified from L. obliqua hemolymph previously shown to have cytoprotective activity had no effect on U138-MG and HT-29; however, this same protein increased the viability of V-79 cells that had previously been exposed to the cytotoxic activity of the crude venom extract. This study indicates that the venom and the antiapoptotic protein act differently and have different effects on cell cultures, depending on the cell line analyzed. Biomolecules displaying either mitogenic or cytotoxic activities are of great biotechnological interest. Further studies encompassing the purification of active principles from L. obliqua venom are necessary to further elucidate its effects on different cell types.     

Flavonoid constituents,cytotoxic and antioxidant activities of Gleditsia triacanthos L. leaves

Gleditsia triacanthos L. is a deciduous tree belonging to the family Fabaceae. It possesses important biological activities as anti-mutagenic, anticancer, cytotoxic and treating rheumatoid arthritis. The total ethanol extract (EtOHE) and successive extracts (petroleum ether, chloroform, ethyl acetate, and aqueous ethanol) were prepared from the leaves. Eight flavone glycosides and two flavone aglycones named vicenin-I (1), vitexin (2), isovitexin (3), orientin (4), isoorientin (5), luteolin-7-O-ß-glucopyranoside (6), luteolin-7-O-ß-galactopyranoside (7), apigenin-7-O-ß-glucopyranoside (8), luteolin (9) and apigenin (10) were isolated from the aqueous ethanol extract of G. triacanthos L. leaves. Potent cytotoxic activity of the EtOHE extract was observed against the liver (IC₅₀ = 1.68 μg), breast (IC₅₀ = 0.74 μg), cervix (IC₅₀ = 1.28 μg), larynx (IC₅₀ = 0.67 μg) and colon (IC₅₀ = 2.50 μg) cancer cell lines. Cytotoxic activity of compounds 2, 4, 6 and 8 against, the liver, breast and colon cancer cell lines was also proved. Evaluation of the in-vivo antioxidant activity of the EtOHE and successive extracts revealed that the highest activity was exhibited by 100 mg of EtOHE (97.89% potency) as compared with vitamin E (100% potency). Compound 6 showed 91.8% free radical scavenging activity.     

The green algae Ulva fasciata Delile extract induces apoptotic cell death in human colon cancer cells

This study investigated the mechanisms underlying the cytotoxicity of the green algae Ulva fasciata Delile. U. fasciata extract (UFE) inhibited the growth of HCT 116 human colon cancer cells by 50% at a concentration of 200 μg/ml. In addition, UFE stimulated the production of intracellular reactive oxygen species, an effect that was abolished by pretreatment with N-acetyl cysteine, which also inhibited the cytotoxic effects of UFE. UFE also induced morphological changes indicative of apoptosis, such as the formation of apoptotic bodies, DNA fragmentation, an increase in the population of apoptotic sub-G₁ phase cells, and mitochondrial membrane depolarization. Concomitant activation of the mitochondria-dependent apoptotic pathway occurred via modulation of Bax and Bcl-2 expression, resulting in disruption of the mitochondrial membrane potential and activation of caspase-9 and caspase-3. This is the first report to demonstrate the cytotoxic effect of U. fasciata on human colon cancer cells and to provide a possible mechanism for this activity.     

Effect of Ottoman Viper (Montivipera xanthina (Gray, 1849)) Venom on Various Cancer Cells and on Microorganisms

Cytotoxic and antimicrobial effects of Montivipera xanthina venom against LNCaP, MCF-7, HT-29, Saos-2, Hep3B, Vero cells and antimicrobial activity against selected bacterial and fungal species: Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, E. coli O157H7, Enterococcus faecalis 29212, Enterococcus faecium DSM 13590, Staphylococcus epidermidis ATCC 12228, S. typhimirium CCM 5445, Proteus vulgaris ATCC 6957 and Candida albicans ATCC 10239 were studied for evaluating the potential medical benefit of this snake venom. Cytotoxicity of venom was determined using MTT assay. Snake venom cytotoxicity was expressed as the venom dose that killed 50 % of the cells (IC₅₀). The antimicrobial activity of venom was studied by minimal inhibitory concentration (MIC) and disc diffusion assay. MIC was determined using broth dilution method. The estimated IC₅₀ values of venom varied from 3.8 to 12.7 or from 1.9 to 7.2 μg/ml after treatment with crude venom for 24 or 48 h for LNCaP, MCF-7, HT-29 and Saos-2 cells. There was no observable cytotoxic effect on Hep3B and Vero cells. Venom exhibited the most potent activity against C. albicans (MIC, 7.8 μg/ml and minimal fungicidal concentration, 62.5 μg/ml) and S. aureus (MIC, 31.25 μg/ml). This study is the first report showing the potential of M. xanthina venom as an alternative therapeutic approach due to its cytotoxic and antimicrobial effects.     

Nitric Oxide Down-Regulates Topoisomerase I and Induces Camptothecin Resistance in Human Breast MCF-7 Tumor Cells

Camptothecin (CPT), a topoisomerase I poison, is an important drug for the treatment of solid tumors in the clinic. Nitric oxide (^·NO), a physiological signaling molecule, is involved in many cellular functions, including cell proliferation, survival and death. We have previously shown that ^·NO plays a significant role in the detoxification of etoposide (VP-16), a topoisomerase II poison in vitro and in human melanoma cells. ^·NO/^·NO-derived species are reported to modulate activity of several important cellular proteins. As topoisomerases contain a number of free sulfhydryl groups which may be targets of ^·NO/^·NO-derived species, we have investigated the roles of ^·NO/^·NO-derived species in the stability and activity of topo I. Here we show that ^·NO/^·NO-derived species induces a significant down-regulation of topoisomerase I protein via the ubiquitin/26S proteasome pathway in human colon (HT-29) and breast (MCF-7) cancer cell lines. Importantly, ^·NO treatment induced a significant resistance to CPT only in MCF-7 cells. This resistance to CPT did not result from loss of topoisomerase I activity as there were no differences in topoisomerase I-induced DNA cleavage in vitro or in tumor cells, but resulted from the stabilization/induction of bcl2 protein. This up-regulation of bcl2 protein in MCF-7 cells was wtp53 dependent as pifithrine-α, a small molecule inhibitor of wtp53 function, completely reversed CPT resistance, suggesting that wtp53 and bcl2 proteins played important roles in CPT resistance. Because tumors in vivo are heterogeneous and contaminated by infiltrating macrophages, ^·NO-induced down-regulation of topoisomerase I protein combined with bcl2 protein stabilization could render certain tumors highly resistant to CPT and drugs derived from it in the clinic.     

Phytochemical and toxicological investigations of crude methanolic extracts,subsequent fractions and crude saponins of Isodon rugosus

Background

Isodon rugosus is used traditionally in the management of hypertension, rheumatism, tooth-ache and pyrexia. Present study was arranged to investigate I. rugosus for phytoconstituents, phytotoxic and cytotoxic activities to explore its toxicological, pharmacological potentials and to rationalize its ethnomedicinal uses. Briefly, qualitative phytochemical analysis of the plant extracts were carried out for the existence of alkaloids, flavonoids, saponins, oils, glycosides, anthraquinones, terpenoids, sterols and tannins. Plant crude methanolic extract (Ir.Cr), its subsequent fractions; n-hexane (Ir.Hex), chloroform (Ir.Chf), ethyl acetate (Ir.EtAc), aqueous (Ir.Aq) and saponins (Ir.Sp) in different concentrations were tested for phytotoxic and cytotoxic activities using radish seeds and brine shrimps (Artemia salina) respectively. The phytotoxic activity was determined by percent root length inhibition (RLI) and percent seeds germination inhibition (SGI) while the cytotoxicity was obtained with percent lethality of the brine shrimps.

Results

Ir.Cr was tested positive for the presence of alkaloids, glycosides, flavonoids, oils, terpenoids, saponins, tannins and anthraquinones. Among different fractions Ir.Sp, Ir.Chf, Ir.EtAc, and Ir.Cr were most effective causing 93.55, 89.32, 81.32 and 58.68% inhibition of seeds in phytotoxicity assay, with IC₅₀ values of 0.1, 0.1, 0.1 and 52 μg/ml respectively. Similarly, among all the tested samples, Ir.Sp exhibited the highest phytotoxic effect causing 91.33% root length inhibition with IC₅₀ of 0.1 μg/ml. Ir.Sp and Ir.Chf were most effective against brine shrimps showing 92.23 and 76.67% lethality with LC₅₀ values of 10 and 12 μg/ml respectively.

Conclusions

It may be inferred from the current investigations that I. rugosus contains different secondary metabolites and is a potential source for the isolation of natural anticancer and herbicidal drug molecules. Different fractions exhibited phytotoxic and cytotoxic activities, thus providing pharmacological basis for ethnomedicinal uses of this plant.     

Extraction of saponins and toxicological profile of Teucrium stocksianum boiss extracts collected from District Swat,Pakistan

Background

The current era is facing challenges in the management of neoplasia and weeds control. The currently available anti-cancer and herbicidal drugs are associated with some serious side effects. Therefore numerous researchers are trying to discover and develop plant based alternative particularly for the rational management of cancer and weed control. Teucrium stocksianum possess antioxidant and analgesic activities. The current study was designed to evaluate crude saponins (CS), methanolic extract and sub-fractions of T. stocksianum for cytotoxic and phytotoxic potentials. CS, methanolic extract and sub-fractions were extracted from powdered plant material using different solvents. Cytotoxic potential of the extracts at a dose of 10, 100 and 1000 μg/ml were evaluated against Brine shrimp’s nauplii. Phytotoxic assay also performed at the same concentration against Lemna minor. Etoposide and Paraquat were used as positive controls in cytotoxic and phytotoxic assays respectively.

Results

The percent yield of crude saponins was (5%). CS demonstrated tremendous brine shrimp lethality showing < 10 μg/ml LC₅₀. The n-hexane (HF) and chloroform fractions (CF) demonstrated excellent cytotoxicity with 80 and 55 μg/ml LC₅₀ respectively. Whereas the methanolic extract (TSME), ethyl acetate (EAF) and aqueous fractions (AF) revealed moderate cytotoxicity showing 620, 860 and 1000 μg/ml LC₅₀ values respectively. In phytotoxic assay profound inhibition was displayed by HF (96.67%) and TSME (95.56%, 30 μg/ml LC₅₀) against the growth of Lemna minor at 1000 μg/ml respectively. Both CF and EAF demonstrated profound phytoxicity (93.33%) respectively at highest concentration (1000 μg/ml), while AF and CS demonstrated weak phytotoxicity with 1350 and 710 μg/ml LC₅₀ values respectively.

Conclusion

Cytotoxicity and phytotoxicity assays indicated that the crude saponins, n-hexane and chloroform fractions of T. stocksianum could play a vital role in the treatment of neoplasia and as potential natural herbicides. Therefore these sub-fractions are recommended for further investigation with the aim to isolate novel anti-cancer and herbicidal compounds.     

Phytochemical study,cytotoxic, analgesic,antipyretic and anti-inflammatory activities of Strychnos nux-vomica

The strychnine tree (Strychnos nux-vomica L.) (S. nux-vomica) belonging to family Loganiaceae has been a very promising medication for certain disorders. Different chromatographic methods were used to isolate the phenolic compounds from the aqueous methanolic extract of the S. nux-vomica leaves. Their identification was achieved through spectroscopic techniques. Cytotoxicity, analgesic, antipyretic and anti-inflammatory activities of S. nux-vomica leaves extract were evaluated. Five phenolic compounds were isolated and identified; Kaempferol-7 glucoside 1, 7-Hydroxy coumarin 2, Quercetin-3-rhamnoside 3, Kaempferol 3-rutinoside 4, and Rutin 5. Furthermore, the cytotoxic activity of the extract was evaluated against different cancer cell lines. The extract showed potential cytotoxic activity against human epidermoid larynx carcinoma cells (Hep-2) and against breast carcinoma cell line (MCF-7). Colon carcinoma cells (HCT) were the least one affected by the extract. In addition, the extract exhibited promising analgesic, antipyretic as well as anti-inflammatory activities. It is concluded that, leaves extract of S. nux vomica possess potent cytotoxic, analgesic, antipyretic and anti-inflammatory activities. These activities could be due to the presence of phenolic compounds revealed by our phytochemical investigations.     

In vivo antipyretic,antiemetic, in vitro membrane stabilization,antimicrobial, and cytotoxic activities of different extracts from Spilanthes paniculata leaves

Background

The study was conducted to evaluate the in vitro antimicrobial activity, cytotoxic, and membrane stabilization activities, and in vivo antiemetic and antipyretic potentials of ethanolic extract, n-hexane and ethyl acetate soluble fractions of Spilanthes paniculata leaves for the first time widely used in the traditional treatments in Bangladesh.

Results

In antipyretic activity assay, a significant reduction (P < 0.05) was observed in the temperature in the mice tested. At dose 400 mg/kg-body weight, the n-hexane soluble fraction showed the effect (36.7 ± 0.63°C ) as like as the standard (dose 150 mg/kg-body weight) after 5 h of administration. Extracts showed significant (P < 0.001) potential when tested for the antiemetic activity compared to the standard, metoclopramide. At dose 50 mg/kg-body weight, the standard showed 67.23% inhibition, whereas n-hexane and ethyl acetate soluble fractions showed 37.53% and 24.93% inhibition of emesis respectively at dose 400 mg/kg-body weight. In antimicrobial activity assay, the n-hexane soluble fraction (400 μg/disc) showed salient activity against the tested organisms. It exerts highest activity against Salmonella typhi (16.9 mm zone of inhibition); besides, crude, and ethyl acetate extracts showed resistance to Bacillus cereus and Bacillus subtilis, and Vibrio cholera respectively. All the extracts were tested for lysis of the erythrocytes. At the concentration of 1mg/ml, ethanol extract, and n-hexane and ethyl acetate soluble fractions significantly inhibited hypotonic solution induced lysis of the human red blood cell (HRBC) (27.406 ± 3.57, 46.034 ± 3.251, and 30.72 ± 5.679% respectively); where standard drug acetylsalicylic acid (concentration 0.1 mg/ml) showed 77.276 ± 0.321% inhibition. In case of heat induced HRBC hemolysis, the plant extracts also showed significant activity (34.21 ± 4.72, 21.81 ± 3.08, and 27.62 ± 8.79% inhibition respectively). In the brine shrimp lethality bioassay, the n-hexane fraction showed potent (LC₅₀ value 48.978 μg/ml) activity, whereas ethyl acetate fraction showed mild (LC₅₀ value 216.77 μg/ml) cytotoxic activity.

Conclusions

Our results showed that the n-hexane extract has better effects than the other in all trials. In the context, it can be said that the leaves of S. paniculata possess remarkable pharmacological effects, and justify its folkloric use as antimicrobial, antipyretic, anti-inflammatory, and antiemetic agent. Therefore, further research may be suggested to find possible mode of action of the plant part.     

Synthesis and biological evaluation of halogenated phenoxychalcones and their corresponding pyrazolines as cytotoxic agents in human breast cancer

Novel halogenated phenoxychalcones 2a–f and their corresponding N-acetylpyrazolines 3a–f were synthesised and evaluated for their anticancer activities against breast cancer cell line (MCF-7) and normal breast cell line (MCF-10a), compared with staurosporine. All compounds showed moderate to good cytotoxic activity when compared to control. Compound 2c was the most active, with IC₅₀ = 1.52 µM and selectivity index = 15.24. Also, chalcone 2f showed significant cytotoxic activity with IC₅₀ = 1.87 µM and selectivity index = 11.03. Compound 2c decreased both total mitogen activated protein kinase (p38α MAPK) and phosphorylated enzyme in MCF-7 cells, suggesting its ability to decrease cell proliferation and survival. It also showed the ability to induce ROS in MCF-7 treated cells. Compound 2c exhibited apoptotic behaviour in MCF-7 cells due to cell accumulation in G2/M phase and elevation in late apoptosis 57.78-fold more than control. Docking studies showed that compounds 2c and 2f interact with p38alpha MAPK active sites.     

Methanol extract from Vietnamese Caesalpinia sappan induces apoptosis in HeLa cells

Background

This study evaluated the cytotoxic activity of extracts from Caesalpinia sappan heartwood against multiple cancer cell lines using an MTT cell viability assay. The cell death though induction of apoptosis was as indicated by DNA fragmentation and caspase-3 enzyme activation.

Results

A methanol extract from C. sappan (MECS) showed cytotoxic activity against several of the cancer cell lines. The most potent activity exhibited by the MECS was against HeLa cells with an IC₅₀ value of 26.5 ± 3.2 μg/mL. Treatment of HeLa cells with various MECS concentrations resulted in growth inhibition and induction of apoptosis, as indicated by DNA fragmentation and caspase-3 enzyme activation.

Conclusion

This study is the first report of the anticancer properties of the heartwood of C. sappan native to Vietnam. Our findings demonstrate that C. sappan heartwood may have beneficial applications in the field of anticancer drug discovery.     

Click chemistry-assisted synthesis of novel aminonaphthoquinone-1,2,3-triazole hybrids and investigation of their cytotoxicity and cancer cell cycle alterations

A series of 12 novel 1,4-naphthoquinone-1,2,3-triazole hybrids were designed and synthesized through copper-catalyzed click reaction of 2-(prop-2-ynylamino)naphthalene-1,4-dione (3) and different azidomethyl-benzene derivatives. The synthesized compounds were assessed for their anticancer activity against three cancer cell lines (MCF-7, HT-29 and MOLT-4) by MTT assay. The results showed that the majority of the synthesized compounds displayed cytotoxic activity. Derivatives 6f and 6h, bearing 4-trifluoromethyl-benzyl and 4-tert-butyl-benzyl groups, respectively, as well as intermediate 3 demonstrated good cytotoxic potential against all tested cancer cell lines, among which compound 6f showed the highest activity. Flow cytometric analysis revealed that compounds 3, 6f and 6h arrested cell cycle at G0/G1 phase in MCF-7 cells. Therefore, synthesized aminonaphthoquinone-1,2,3-triazole derivatives can be introduced as promising molecules for further development as potential anticancer agents.     

Inhibition of Human MCF-7 Breast Cancer Cells and HT-29 Colon Cancer Cells by Rice-Produced Recombinant Human Insulin-Like Growth Binding Protein-3 (rhIGFBP-3)

Background

Insulin-like growth factor binding protein-3 (IGFBP-3) is a multifunctional molecule which is closely related to cell growth, apoptosis, angiogenesis, metabolism and senescence. It combines with insulin-like growth factor-I (IGF-I) to form a complex (IGF-I/IGFBP-3) that can treat growth hormone insensitivity syndrome (GHIS) and reduce insulin requirement in patients with diabetes. IGFBP-3 alone has been shown to have anti-proliferation effect on numerous cancer cells.

Methodology/Principal Findings

We reported here an expression method to produce functional recombinant human IGFBP-3 (rhIGFBP-3) in transgenic rice grains. Protein sorting sequences, signal peptide and endoplasmic reticulum retention tetrapeptide (KDEL) were included in constructs for enhancing rhIGFBP-3 expression. Western blot analysis showed that only the constructs with signal peptide were successfully expressed in transgenic rice grains. Both rhIGFBP-3 proteins, with or without KDEL sorting sequence inhibited the growth of MCF-7 human breast cancer cells (65.76 ± 1.72% vs 45.00 ± 0.86%, p < 0.05; 50.84 ± 1.97% vs 45.00 ± 0.86%, p < 0.01 respectively) and HT-29 colon cancer cells (65.14 ±3.84% vs 18.01 ± 13.81%, p < 0.05 and 54.7 ± 9.44% vs 18.01 ± 13.81%, p < 0.05 respectively) when compared with wild type rice.

Conclusion/Significance

These findings demonstrated the feasibility of producing biological active rhIGFBP-3 in rice using a transgenic approach, which will definitely encourage more research on the therapeutic use of hIGFBP-3 in future.     

Anti-tumoral activity of imidazoquines,a new class of antimalarials derived from primaquine

The growth inhibitory activity of imidazoquines, antimalarial imidazolidin-4-ones derived from primaquine, on human cancer cell lines HT-29, Caco-2, and MCF-7 has been evaluated. Primaquine, N-dipeptidyl-primaquine derivatives, and other quinolines have been included in the study for comparison purposes. Primaquine and some of its derivatives were significantly active against the MCF-7 human breast cancer cell line, so these compounds might represent useful leads targeted at the development of novel specific agents against breast cancer. Conversely, all compounds were generally inactive against HT-29, with only one of the imidazoquines having IC₅₀ below 50 μM. Activities against the Caco-2 cell line were modest and did not follow any defined trend.     

Combination of gastrin-releasing peptide antagonist with cytotoxic agents produces synergistic inhibition of growth of human experimental colon cancers

We investigated the efficacy of a powerful antagonist of bombesin/gastrin-releasing peptide (BN/GRP) RC-3940-II administered as a single agent or in combination with cytotoxic agents on the growth of HT-29, HCT-116 and HCT-15 human colon cancer in vitro and in vivo. GRP-receptor mRNA and protein were found in all three cell lines tested. Exposure of HT-29 cells to 10 μM RC-3940-II led to an increase in the number of cells blocked in S phase and G₂/M and cells with lower G₀/G₁ DNA content. Similar changes on the cell cycle traverse of HT-29 cells could also be seen at lower concentrations of RC-3940-II (1 μM) after pretreatment with 100 nM GRP (14–27), indicating a dose-dependent mechanism of action based on the blockage of BN/GRP induced proliferation of tumor cells at lower concentrations. Daily in vivo treatment with BN/GRP antagonist RC-3940-II decreased the volume of HT-29, HCT-116 and HCT-15 tumors xenografted into athymic nude mice by 25 to 67% (p < 0.005). Combined treatment with RC-3940-II and chemotherapeutic agents 5-FU and irinotecan resulted in a synergistic tumor growth suppression of HT-29, HCT-116 and HCT-15 xenografts by 43% to 78%. In HT-29 and HCT-116 xenografts the inhibition for the combinations of RC-3940-II and irinotecan vs. single substances (p < 0.05) was significantly greater. These findings support the use of RC-3940-II as an anticancer agent and may help to design clinical trials using RC-3940-II in combinations with cytotoxic agents.     

C29 sterols with a cyclopropane ring at C-25 and 26 from the Vietnamese marine sponge Ianthella sp. and their anticancer properties

Two new C₂₉ sterols with a cyclopropane ring at C-25 and C-26, petrosterol-3,6-dione (1) and 5α,6α-epoxy-petrosterol (2), along with petrosterol (3), were isolated from the Vietnamese marine sponge Ianthella sp. The structures of the new compounds were elucidated by comprehensive spectroscopic analyses. Compounds 1?3 showed cytotoxic activities on A549, HL-60, MCF-7, SK-OV-3, and U937 cancer cell lines with IC₅₀ in the range of 8.4–22.6 μM, whereas compounds 1?3 exhibited only weak cytotoxic activities on HT-29 cell. After HL-60 cells were treated with the compounds, several apoptosis events like chromatin condensation and the increase of the population of sub-G1 hypodiploid cells were observed. These data supported that the compounds might have potential for leukemia treatment.