Exploring the multifaceted effects of Ammi visnaga: subchronic toxicity, antioxidant capacity, immunomodulatory, and anti-inflammatory activities

Ammi visnaga (A. visnaga) is an annual herb that has been used in traditional medicine to treat various ailments attributed to the presence of its bioactive compounds. The purpose of this study was to identify and examine the phytochemical properties of the hydroalcoholic extract of A. visnaga using in vitro and in vivo models. Our findings demonstrated that the extract contained a variety of beneficial components, including phenols, flavonoids, tannins, coumarins, saponins, khellin, and visnagin. The total polyphenolic content and total flavonoid content were 23.26 mg/GAE/g dry weight and 13.26 mg/GAE/g dry weight, respectively. In vitro tests demonstrated that the extract possessed antioxidant properties as evidenced by the ability to scavenge free radicals, including DPPH, ABTS, nitric oxide (NO), phosphomolybdate, and ferric-reducing antioxidant power (FRAP). Further, the extract was found to inhibit hydrogen peroxide (H2O2)-induced hemolysis. In a 90-d in vivo study, female Wistar rats were administered 1 g/kg of A. visnaga extract orally resulting in a significant increase in total white blood cell count. Although morphological changes were observed in the liver, no marked alterations were noted in kidneys and spleen. In a female Swiss albino mice model of acetic acid-induced vascular permeability, A. visnaga significantly inhibited extravasations of Evans blue at doses of 0.5 or 1 g/kg with inhibition percentages of 51 and 65%, respectively, blocking tissue necrosis. The extract also demonstrated potential immunomodulatory properties in mice by enhancing antibody production in response to antigens. In silico molecular docking studies demonstrated a strong affinity between khellin or visnagin and immunomodulatory proteins, NF-κB, p52, and TNF-α. These findings suggest that A. visnaga may be considered a beneficial antioxidant with immunomodulatory properties and might serve as a therapeutic agent to combat certain diseases.

Ursolic Acid's Alluring Journey: One Triterpenoid vs. Cancer Hallmarks

Cancer is a multifactorial disease characterized by various hallmarks, including uncontrolled cell growth, evasion of apoptosis, sustained angiogenesis, tissue invasion, and metastasis, among others. Traditional cancer therapies often target specific hallmarks, leading to limited efficacy and the development of resistance. Thus, there is a growing need for alternative strategies that can address multiple hallmarks concomitantly. Ursolic acid (UA), a naturally occurring pentacyclic triterpenoid, has recently emerged as a promising candidate for multitargeted cancer therapy. This review aims to summarize the current knowledge on the anticancer properties of UA, focusing on its ability to modulate various cancer hallmarks. The literature reveals that UA exhibits potent anticancer effects through diverse mechanisms, including the inhibition of cell proliferation, induction of apoptosis, suppression of angiogenesis, inhibition of metastasis, and modulation of the tumor microenvironment. Additionally, UA has demonstrated promising activity against different cancer types (e.g., breast, lung, prostate, colon, and liver) by targeting various cancer hallmarks. This review discusses the molecular targets and signaling pathways involved in the anticancer effects of UA. Notably, UA has been found to modulate key signaling pathways, such as PI3K/Akt, MAPK/ERK, NF-κB, and Wnt/β-catenin, which play crucial roles in cancer development and progression. Moreover, the ability of UA to destroy cancer cells through various mechanisms (e.g., apoptosis, autophagy, inhibiting cell growth, dysregulating cancer cell metabolism, etc.) contributes to its multitargeted effects on cancer hallmarks. Despite promising anticancer effects, this review acknowledges hurdles related to UA's low bioavailability, emphasizing the need for enhanced therapeutic strategies.

Natural Chalcones and Derivatives in Colon Cancer: Pre-Clinical Challenges and the Promise of Chalcone-Based Nanoparticles

Colon cancer poses a complex and substantial global health challenge, necessitating innovative therapeutic approaches. Chalcones, a versatile class of compounds with diverse pharmacological properties, have emerged as promising candidates for addressing colon cancer. Their ability to modulate pivotal signaling pathways in the development and progression of colon cancer makes them invaluable as targeted therapeutics. Nevertheless, it is crucial to recognize that although chalcones exhibit promise, further pre-clinical studies are required to validate their efficacy and safety. The journey toward effective colon cancer treatment is multifaceted, involving considerations such as optimizing the sequencing of therapeutic agents, comprehending the resistance mechanisms, and exploring combination therapies incorporating chalcones. Furthermore, the integration of nanoparticle-based drug delivery systems presents a novel avenue for enhancing the effectiveness of chalcones in colon cancer treatment. This review delves into the mechanisms of action of natural chalcones and some derivatives. It highlights the challenges associated with their use in pre-clinical studies, while also underscoring the advantages of employing chalcone-based nanoparticles for the treatment of colon cancer.

The Promise of Piperine in Cancer Chemoprevention

Cancer, characterized by the unregulated growth and dissemination of malignantly transformed cells, presents a significant global health challenge. The multistage process of cancer development involves intricate biochemical and genetic alterations within target cells. Cancer chemoprevention has emerged as a vital strategy to address this complex issue to mitigate cancer's impact on healthcare systems. This approach leverages pharmacologically active agents to block, suppress, prevent, or reverse invasive cancer development. Among these agents, piperine, an active alkaloid with a wide range of therapeutic properties, including antioxidant, anti-inflammatory, and immunomodulatory effects, has garnered attention for its potential in cancer prevention and treatment. This comprehensive review explores piperine's multifaceted role in inhibiting the molecular events and signaling pathways associated with various stages of cancer development, shedding light on its promising prospects as a versatile tool in cancer chemoprevention. Furthermore, the review will also delve into how piperine enhances the effectiveness of conventional treatments such as UV-phototherapy and TRAIL-based therapy, potentially synergizing with existing therapeutic modalities to provide more robust cancer management strategies. Finally, a crucial perspective of the long-term safety and potential side effects of piperine-based therapies and the need for clinical trials is also discussed.

Polyphenol-Based Nanoparticles: A Promising Frontier for Enhanced Colorectal Cancer Treatment

Colorectal cancer (CRC) poses a significant challenge in healthcare, necessitating the exploration of novel therapeutic strategies. Natural compounds such as polyphenols with inherent anticancer properties have gained attention as potential therapeutic agents. This review highlights the need for novel therapeutic approaches in CRC, followed by a discussion on the synthesis of polyphenols-based nanoparticles. Various synthesis techniques, including dynamic covalent bonding, non-covalent bonding, polymerization, chemical conjugation, reduction, and metal-polyphenol networks, are explored. The mechanisms of action of these nanoparticles, encompassing passive and active targeting mechanisms, are also discussed. The review further examines the intrinsic anticancer activity of polyphenols and their enhancement through nano-based delivery systems. This section explores the natural anticancer properties of polyphenols and investigates different nano-based delivery systems, such as micelles, nanogels, liposomes, nanoemulsions, gold nanoparticles, mesoporous silica nanoparticles, and metal-organic frameworks. The review concludes by emphasizing the potential of nanoparticle-based strategies utilizing polyphenols for CRC treatment and highlights the need for future research to optimize their efficacy and safety. Overall, this review provides valuable insights into the synthesis, mechanisms of action, intrinsic anticancer activity, and enhancement of polyphenols-based nanoparticles for CRC treatment.

Shining a Light on Prostate Cancer: Photodynamic Therapy and Combination Approaches

Prostate cancer is a major health concern worldwide, and current treatments, such as surgery, radiation therapy, and chemotherapy, are associated with significant side effects and limitations. Photodynamic therapy (PDT) is a promising alternative that has the potential to provide a minimally invasive and highly targeted approach to treating prostate cancer. PDT involves the use of photosensitizers (PSs) that are activated by light to produce reactive oxygen species (ROS), which can induce tumor cell death. There are two main types of PSs: synthetic and natural. Synthetic PSs are classified into four generations based on their structural and photophysical properties, while natural PSs are derived from plant and bacterial sources. Combining PDT with other therapies, such as photothermal therapy (PTT), photoimmunotherapy (PIT), and chemotherapy (CT), is also being explored as a way to improve its efficacy. This review provides an overview of conventional treatments for prostate cancer, the underlying principles of PDT, and the different types of PSs used in PDT as well as ongoing clinical studies. It also discusses the various forms of combination therapy being explored in the context of PDT for prostate cancer, as well as the challenges and opportunities associated with this approach. Overall, PDT has the potential to provide a more effective and less invasive treatment option for prostate cancer, and ongoing research is aimed at improving its selectivity and efficacy in clinical settings.

Antitumoral activity of Caralluma europaea on colorectal and prostate cancer cell lines

Caralluma europaea is a medicinal plant used in Moroccan popular medicine, which has been employed as a remedy attributed to its anti-inflammatory, antipyretic, antinociceptive, antidiabetic, neuroprotective, and antiparasitic properties. The aim of the present study was to investigate the antitumor activity of both the methanolic and aqueous extract of C. europaea. The effects of increasing concentrations of aqueous and methanolic extracts on human colorectal cancer HT-29 and HCT116 cell lines and human prostate cancer PC3 and DU145 cell lines were examined on cell proliferation using MTT assay and cell cycle analysis. The induction of apoptosis was also assessed by determining protein expression of caspase-3 and poly-ADP-ribose polymerase (PARP) cleavage by western blot. The methanolic extract of C. europaea exerted significant antiproliferative effects on HT-29 (IC₅₀ values 73 µg/ml), HCT116 (IC₅₀ values 67 µg/ml), PC3 (IC₅₀ values 63 µg/ml) and DU145 cells (IC₅₀ values 65 µg/ml) after 48 hr treatment. Further, incubation with methanolic extract of C. europaea induced cell cycle arrest in G1 phase and an apoptotic process for all treated cell lines. In conclusion, the present results suggest that C. europaea, exhibited that these natural compounds are significant apoptosis inducers which may have considerable potential for development of effective natural product anticancer agents.

Antioxidant and Polyphenol-Rich Ethanolic Extract of Rubia tinctorum L. Prevents Urolithiasis in an Ethylene Glycol Experimental Model in Rats

Treatment of kidney stones is based on symptomatic medications which are associated with side effects such as gastrointestinal symptoms (e.g., nausea, vomiting) and hepatotoxicity. The search for effective plant extracts without the above side effects has demonstrated the involvement of antioxidants in the treatment of kidney stones. A local survey in Morocco has previously revealed the frequent use of Rubia tinctorum L. (RT) for the treatment of kidney stones. In this study, we first explored whether RT ethanolic (E-RT) and ethyl acetate (EA-RT) extracts of Rubia tinctorum L. could prevent the occurrence of urolithiasis in an experimental 0.75% ethylene glycol (EG) and 2% ammonium chloride (AC)-induced rat model. Secondly, we determined the potential antioxidant potency as well as the polyphenol composition of these extracts. An EG/AC regimen for 10 days induced the formation of bipyramid-shaped calcium oxalate crystals in the urine. Concomitantly, serum and urinary creatinine, urea, uric acid, phosphorus, calcium, sodium, potassium, and chloride were altered. The co-administration of both RT extracts prevented alterations in all these parameters. In the EG/AC-induced rat model, the antioxidants- and polyphenols-rich E-RT and EA-RT extracts significantly reduced the presence of calcium oxalate in the urine, and prevented serum and urinary biochemical alterations together with kidney tissue damage associated with urolithiasis. Moreover, we demonstrated that the beneficial preventive effects of E-RT co-administration were more pronounced than those obtained with EA-RT. The superiority of E-RT was associated with its more potent antioxidant effect, due to its high content in polyphenols.

Ibuprofen-loaded calcium phosphate granules: A new bone substitute for local relieving symptoms of osteoarthritis

Musculoskeletal diseases often demand a drug treatment at the specific site of injury or defect site. In this context, the use of calcium phosphates is attractive as it allows both the bone substitution and the local delivery of a drug substance. In this work, we present a drug delivery device that combines calcium phosphate bioceramic granules and ibuprofen, a widely used anti-inflammatory drug. After verifying in vitro biocompatibility of the ibuprofen-loaded calcium phosphate granules on murine preosteoblastic cells (MC3T3), we evaluated in vitro efficiency of the drug substance released from the bioceramic using rheumatoid arthritis synoviocytes. Our data document that ibuprofen-loaded calcium phosphate granules reduced inflammatory response and increased apoptosis of synoviocytes. In vivo study showed that both unloaded, and ibuprofen-loaded calcium phosphate granules induced a progressive osteogenesis, but in the case of ibuprofen-loaded implants, bone ingrowth was more limited in first weeks. However, as far as concerns inflammation, while unloaded granules showed inflammation up to 4 weeks, ibuprofen loaded granules did not show any significant inflammation. Ibuprofen concentration determination in blood samples showed that a very small amount of the drug reached the general circulation which render this drug delivery system suitable for both bone substitution and reduction of inflammation at the implantation site. Thus, this new drug carrier could be used to locally relieve inflammatory bone diseases symptoms including rheumatoid arthritis but, beyond this study, this kind of granules could be considered for the delivery of therapeutic agents such as antibiotic, analgesic or anticancer drugs.

Platelets Can Associate with SARS-Cov-2 RNA and Are Hyperactivated in COVID-19

Rationale: In addition to the overwhelming lung inflammation that prevails in COVID-19, hypercoagulation and thrombosis contribute to the lethality of subjects infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Platelets are chiefly implicated in thrombosis. Moreover, they can interact with viruses and are an important source of inflammatory mediators. While a lower platelet count is associated with severity and mortality, little is known about platelet function during COVID-19. Objective: To evaluate the contribution of platelets to inflammation and thrombosis in COVID-19 patients. Methods and Results: Blood was collected from 115 consecutive COVID-19 patients presenting non-severe (n=71) and severe (n=44) respiratory symptoms. We document the presence of SARS-CoV-2 RNA associated with platelets of COVID-19 patients. Exhaustive assessment of cytokines in plasma and in platelets revealed the modulation of platelet-associated cytokine levels in both non-severe and severe COVID-19 patients, pointing to a direct contribution of platelets to the plasmatic cytokine load. Moreover, we demonstrate that platelets release their alpha- and dense-granule contents in both non-severe and severe forms of COVID-19. In comparison to concentrations measured in healthy volunteers, phosphatidylserine-exposing platelet extracellular vesicles were increased in non-severe, but not in severe cases of COVID-19. Levels of D-dimers, a marker of thrombosis, failed to correlate with any measured indicators of platelet activation. Functionally, platelets were hyperactivated in COVID-19 subjects presenting non-severe and severe symptoms, with aggregation occurring at suboptimal thrombin concentrations. Furthermore, platelets adhered more efficiently onto collagen-coated surfaces under flow conditions. Conclusions: Taken together, the data suggest that platelets are at the frontline of COVID-19 pathogenesis, as they release various sets of molecules through the different stages of the disease. Platelets may thus have the potential to contribute to the overwhelming thrombo-inflammation in COVID-19, and the inhibition of pathways related to platelet activation may improve the outcomes during COVID-19.

[Current antiplatelet agents, new inhibitors and therapeutic targets]

Cardiovascular diseases are the leading cause of deaths in the world. Platelets play a major role in the occurrence of these diseases and the development of antiplatelet drugs is a priority in the fight against cardiovascular diseases-associated mortality. Aspirin and thienopyridine-based P2Y12 inhibitors are the main drugs currently used. These molecules target the initiation of platelets activation and are responsible for a moderate inhibitory action. Other antiplatelet agents, as glycoprotein (GP) IIb/IIIa antagonists, inhibit platelet aggregation independently of initial activation-associated pathways, but are responsible for increased hemorrhagic events. Regarding each antiplatelet agent's specific characteristics, the prescription of these drugs must take into account the type of cardiovascular event, the age of the patient, the past medical history, and the potential hemorrhagic adverse events. Thus, there is a need for the development of new molecules with a more targeted effect, maintaining optimal efficiency but with a reduction of the hemorrhagic risk, which is the principal limitation of these treatments.

Antitumoral activity of Ficus carica L. on colorectal cancer cell lines

In traditional medicine, Ficus carica (also known as fig) latex is recognized as a remedy with various therapeutic effects. In the present study we investigated the antitumor activity of Ficus carica extracts and latex. We evaluated the effects of increasing concentrations of Ficus carica extracts and latex on HCT-116 and HT-29 human colorectal cell proliferation using MTT assay and apoptosis induction by evaluating PARP cleavage by Western blot analysis. Peel, pulp, leaves, whole fruit and latex extracts of Ficus carica exerted significant antiproliferative effects on HCT-116 (IC50 values 239, 343, 177, 299, 206 µg/ml) and HT-29 cells (IC50 values 207, 249, 230, 261, 182 µg/ml) after 48h of treatment. Furthermore, treatment with different extracts of Ficus carica induced apoptosis in both HT-29 and HCT-116 cancer cells. Leaves and latex extracts of Ficus carica showed the strongest antiproliferative activities. Overall, our results showed that these natural products are strong apoptosis inducers which suggest their use of for therapeutic purposes.

Coverage rate of ADME genes from commercial sequencing arrays

Pharmacogenomics offers remarkable potential for the rapid translation of discoveries into changes in clinical practice. In the present work, we are interested in evaluating the ability of commercially available genome-wide association sequencing chips to cover genes that have high pharmacogenomics potential.We used a set of 2794 variations within 369 absorption, distribution, metabolism, and elimination (ADME) genes of interest, as previously defined in collaboration with the Pharma ADME consortium. We have compared the Illumina TrueSeq and both Agilent SureSelect and HaloPlex sequencing technologies. We have developed Python scripts to evaluate the coverage for each of these products. In particular, we considered a specific list of 155 allelic variants in 34 genes which present high pharmacogenomics potential. Both the theoretical and practical coverage was assessed.Given the need to have a good coverage to establish confidently the functionality of an enzyme, the observed rates are unlikely to provide sufficient evidence for pharmacogenomics studies. We assessed the coverage using enrichment technology for exome sequencing using the Illumina Trueseq exome, Agilent SureSelectXT1 V4 and V5, and Haloplex exome, which offer a coverage of 96.12%, 91.61%, and 88.38%, respectively.Although pharmacogenomic advances had been limited in the past due in part to the lack of coverage of commercial genotyping chips, it is anticipated that future studies that make use of new sequencing technologies should offer a greater potential for discovery.

Resistance to ursolic acid-induced apoptosis through involvement of melanogenesis and COX-2/PGE2 pathways in human M4Beu melanoma cancer cells

Melanoma is one of the most aggressive forms of cancer with a continuously growing incidence worldwide and is usually resistant to chemotherapy agents, which is due in part to a strong resistance to apoptosis. Previously, we had showed that B16-F0 murine melanoma cells undergoing apoptosis are able to delay their own death induced by ursolic acid (UA), a natural pentacyclic triterpenoid compound. We had demonstrated that tyrosinase and TRP-1 up-regulation in apoptotic cells and the subsequent production of melanin were implicated in an apoptosis resistance mechanism. Several resistance mechanisms to apoptosis have been characterized in melanoma such as hyperactivation of DNA repair mechanisms, drug efflux systems, and reinforcement of survival signals (PI3K/Akt, NF-κB and Raf/MAPK pathways). Otherwise, other mechanisms of apoptosis resistance involving different proteins, such as cyclooxygenase-2 (COX-2), have been described in many cancer types. By using a strategy of specific inhibition of each ways, we suggested that there was an interaction between melanogenesis and COX-2/PGE2 pathway. This was characterized by analyzing the COX-2 expression and activity, the expression of tyrosinase and melanin production. Furthermore, we showed that anti-proliferative and proapoptotic effects of UA were mediated through modulation of multiple signaling pathways including Akt and ERK-1/2 proteins. Our study not only uncovers underlying molecular mechanisms of UA action in human melanoma cancer cells but also suggest its great potential as an adjuvant in treatment and cancer prevention.

TRAIL and targeting cancer cells: between promises and obstacles

Targeting cancer cells is one of the challenges of current treatment strategies. TRAIL represents a promising therapeutic approach and over the past decades there was an increased interest in targeting TRAIL signaling to treat cancer. Indeed, TRAIL can specifically target cancer cells and exhibits very low cytotoxicity towards normal cells. However, rapidly accumulating experimental evidence has started to shed light on multiple factors which induce resistance against TRAIL in cancer cells. This resistance consists of various mechanisms including downregulation of death receptors and caspase-8 and overexpression of decoy receptors as well as antiapoptotic factors such as members of Bcl-2 family. Even if several studies focused on elucidating those resistance mechanisms, there still remain gray areas that need to be fully elucidated. Thus, therapeutic approaches could consist of targeting both resistance signaling pathways and TRAIL signaling to enhance TRAIL therapy efficiency.

Sonic Hedgehog activation is implicated in diosgenin-induced megakaryocytic differentiation of human erythroleukemia cells

Differentiation therapy is a means to treat cancer and is induced by different agents with low toxicity and more specificity than traditional ones. Diosgenin, a plant steroid, is able to induce megakaryocytic differentiation or apoptosis in human HEL erythroleukemia cells in a dose-dependent manner. However, the exact mechanism by which diosgenin induces megakaryocytic differentiation has not been elucidated. In this study, we studied the involvement of Sonic Hedgehog in megakaryocytic differentiation induced by diosgenin in HEL cells. First, we showed that different elements of the Hedgehog pathway are expressed in our model by qRT-PCR. Then, we focused our interest on key elements in the Sonic Hedgehog pathway: Smoothened receptor, GLI transcription factor and the ligand Sonic Hedgehog. We showed that Smoothened and Sonic Hedgehog were overexpressed in disogenin-treated cells and that GLI transcription factors were activated. Then, we showed that SMO inhibition using siSMO or the GLI antagonist GANT-61, blocked megakaryocytic differentiation induced by diosgenin in HEL cells. Furthermore, we demonstrated that Sonic Hedgehog pathway inhibition led to inhibition of ERK1/2 activation, a major physiological pathway involved in megakaryocytic differentiation. In conclusion, our study reports, for the first time, a crucial role for the Sonic Hedgehog pathway in diosgenin-induced megakaryocytic differentiation in HEL cells.

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.

Cyclopamine and jervine induce COX-2 overexpression in human erythroleukemia cells but only cyclopamine has a pro-apoptotic effect

Erythroleukemia is generally associated with a very poor response and survival to current available therapeutic agents. Cyclooxygenase-2 (COX-2) has been described to play a crucial role in the proliferation and differentiation of leukemia cells, this enzyme seems to play an important role in chemoresistance in different cancer types. Previously, we demonstrated that diosgenin, a plant steroid, induced apoptosis in HEL cells with concomitant COX-2 overexpression. In this study, we investigated the antiproliferative and apoptotic effects of cyclopamine and jervine, two steroidal alkaloids with similar structures, on HEL and TF1a human erythroleukemia cell lines and, for the first time, their effect on COX-2 expression. Cyclopamine, but not jervine, inhibited cell proliferation and induced apoptosis in these cells. Both compounds induced COX-2 overexpression which was responsible for apoptosis resistance. In jervine-treated cells, COX-2 overexpression was NF-κB dependent. Inhibition of NF-κB reduced COX-2 overexpression and induced apoptosis. In addition, cyclopamine induced apoptosis and COX-2 overexpression via PKC activation. Inhibition of the PKC pathway reduced both apoptosis and COX-2 overexpression in both cell lines. Furthermore, we demonstrated that the p38/COX-2 pathway was involved in resistance to cyclopamine-induced apoptosis since p38 inhibition reduced COX-2 overexpression and increased apoptosis in both cell lines.

The P2Y2/Src/p38/COX-2 pathway is involved in the resistance to ursolic acid-induced apoptosis in colorectal and prostate cancer cells

One of the hallmarks of cancer is resistance to apoptosis. Elucidating the mechanisms of how cancer cells evade or delay apoptosis should lead to novel therapeutic strategies. Previously, we showed that HT-29 colorectal cancer cells undergoing apoptosis overexpressed cyclooxygenase-2 (COX-2), in a p38 dependent pathway, to delay ursolic acid-induced apoptosis. Here, we focused on elucidating the upstream signaling pathways regulating this resistance mechanism. The role of ATP as an extracellular signaling molecule took a long time to be accepted. In recent years, ATP and its analogs, via the activation of specific purinergic receptors, have been implicated in many biological processes including cell proliferation, differentiation and apoptosis. In the present report, we have demonstrated a novel role involving purinergic receptors and particularly the P2Y(2) receptor in resistance to ursolic acid-induced apoptosis in both colorectal HT-29 and prostate DU145 cancer cells. We found that ursolic acid induced an increase in intracellular ATP and P2Y(2) transcript levels. Upon activation, P2Y(2) activated Src which in turn phosphorylated p38 leading to COX-2 overexpression which induced resistance to apoptosis in both HT-29 and DU145 cells. Furthermore, Ca(2+)-independent PLA(2) (iPLA(2)) and Ca(2+)-dependent secretory PLA(2) (sPLA(2)) were responsible for arachidonic acid release, the substrate of COX-2. Our findings document that apoptosis triggering was dependent on protein kinase C (PKC) activation in both cell lines after ursolic acid treatment.

A novel form of melanoma apoptosis resistance: melanogenesis up-regulation in apoptotic B16-F0 cells delays ursolic acid-triggered cell death

Melanoma is one of the most aggressive forms of cancer with a continuously growing incidence worldwide and is usually resistant to chemotherapy agents, which is due in part to a strong resistance to apoptosis. The resistance mechanisms are complex and melanoma cells may have diverse possibilities for regulating apoptosis to generate apoptotic deficiencies. In this study, we investigated the relationship between melanogenesis and resistance to apoptosis induced by ursolic acid, a natural chemopreventive agent, in B16-F0 melanoma cells. We demonstrated that cells undergoing apoptosis are able to delay their own death. It appeared that tyrosinase and TRP-1 up-regulation in apoptotic cells and the subsequent production of melanin were clearly implicated in an apoptosis resistance mechanism; while TRP-2, a well known mediator of melanoma resistance to cell death, was repressed. Our results confirm the difficulty of treating melanomas, since, even undergoing apoptosis, cells are nevertheless able to trigger a resistance mechanism to delay death.

HT-29 colorectal cancer cells undergoing apoptosis overexpress COX-2 to delay ursolic acid-induced cell death

Colorectal cancer is one of the most common cancer types and the third leading cause of cancer-related death in the western world. Generally, colorectal cancers are resistant to anticancer drugs. Several lines of evidence support a critical role for cyclooxygenase-2 (COX-2) during colorectal tumorigenesis and its role in chemoresistance. In this study, we focused our interest on the role played by COX-2 in apoptosis induced in HT-29 human colorectal cancer cells by ursolic acid (UA), a triterpenoid found in a large variety of plants. We showed that UA-induced apoptosis and that COX-2 was overexpressed only in apoptotic cells. We demonstrated that this overexpression was mediated by the p38 MAP kinase pathway as inhibiting its activation using a p38-specific inhibitor, SB 203580, abrogated COX-2 expression. Inhibiting COX-2 expression either by using a p38-specific inhibitor or COX-2-specific siRNA increased apoptosis. These results demonstrated that COX-2 was involved in a resistance mechanism to UA-induced apoptosis in HT-29 cells. Cells undergoing apoptosis were able to trigger a resistance mechanism by overexpressing a protein such as COX-2 to delay their death. Furthermore, we demonstrated that this resistance mechanism was independent of PGE(2) production as the addition of the specific COX-2 activity inhibitor, NS-398, did not affect apoptosis in UA-treated cells.

Dosimetric characteristics of the CDC-type miniature cylindrical 137Cs brachytherapy sources

The low dose rate CDC-type miniature cylindrical 137Cs sources are available, with one or three active beads, for use in source trains in automatic and manual afterloading systems for gynecological brachytherapy. Absolute dose rate distributions in water have been calculated around these sources using the Monte Carlo GEANT3 code and they are presented as conventional two-dimensional Cartesian lookup tables. The AAPM Task Group 43 formalism for dose calculation has been also applied. The dose rate constant obtained for the one bead source is lambda = 1.113 +/- 0.003cGyh(-1) U(-1), and the value for the three bead source is A= 1.103 +/- 0.003cGyh(-1) U(-1). Finally, for the treatment planning systems based on Sievert-type algorithms, the attenuation coefficients that best reproduce Monte Carlo dose rate distribution are given.

Dosimetry characteristics of the Plus and 12i Gammamed PDR 192Ir sources

In this study a complete set of dosimetric data for the Plus and 12i Gammamed PDR (pulsed dose rate) 192Ir sources is presented. These data have been calculated using the Monte Carlo simulation code GEANT3. Absolute dose rate distributions in water around these sources were calculated and are presented in form of conventional two dimensional (2D) Cartesian look-up tables. All dosimetric quantities recommended by the AAPM Task Group 43 report have been also calculated. These quantities are dose rate constant, radial dose function, anisotropy function and anisotropy factor. The dose rate distribution of the 12i source was compared with the corresponding data for the microselectron PDR source showing large differences between both sources.

Technical note: Monte-Carlo dosimetry of the HDR 12i and Plus 192Ir sources

In this study a complete set of dosimetric data for the GammaMed high dose rate (HDR) 12i and Plus 192Ir sources are presented. These data have been calculated by means of the Monte Carlo simulation code GEANT3. Absolute dose rate distributions in water are presented as conventional two dimensional (2D) Cartesian look-up tables, and in the TG43 formalism.

Assessment of the linear reference air kerma rate of 192Ir wires

In this study, a procedure to test the linear reference air kerma rate of 192Ir wires using a well-type chamber is described. The method is based on a special lead insert with a 1 cm acrylic aperture that provides a differential response of the well chamber. The wire is considered divided into 1 cm parts. Using an external positioning system it is possible to place every part of the wire at the aperture position in the lead insert allowing measurement of each 1 cm making up the length of the wire. By means of a set of equations that take into account the contribution of all parts of the wire, in all possible positions, the relative linear reference air kerma rate is obtained. The estimated uncertainties of this procedure are about 2 to 3%. So, a well chamber and the specific inserts allow the measurements of total and linear reference air kerma rate for 192Ir wires.

Monte Carlo calculation of dose rate distributions around the Walstam CDC.K-type 137Cs sources

Basic dosimetric data for the Walstam CDC.K-type low dose rate 137Cs sources in water have been calculated using Monte Carlo techniques. These sources, CDC.K1 -K3 and CDC.K4, are widely used in a range of applicators and moulds for the treatment of intracavitary and superficial cancers. Our purpose is to improve existing data about these sources using the Monte Carlo simulation code GEANT3. Absolute dose rate distributions in water have been calculated around these sources and are presented as conventional 2D Cartesian look-up tables. Also the AAPM Task Group 43 formalism for dose calculation has been applied. The calculated dose rate constant for the CDC.K1-K3 source is A = 1.106 +/- 0.001 cGy h(-1) U(-1), and for the CDC.K4 source, A = 1.092 +/- 0.001 cGy h(-1) U(-1). The anisotropy of the sources are accurately studied and F(r, theta) tables are given. Also phi an(r) factors are presented. The radial dose functions are given as a polynomial fit to the calculated data up to 15 cm. Best-fit values of coefficients suitable for use in Sievert integral calculations have been derived.

A monte carlo study of dose rate distribution around the specially asymmetric CSM3-a 137Cs source

The CSM3 137Cs type stainless-steel encapsulated source is widely used in manually afterloaded low dose rate brachytherapy. A specially asymmetric source, CSM3-a, has been designed by CIS Bio International (France) substituting the eyelet side seed with an inactive material in the CSM3 source. This modification has been done in order to allow a uniform dose level over the upper vaginal surface when this 'linear' source is inserted at the top of the dome vaginal applicators. In this study the Monte Carlo GEANT3 simulation code, incorporating the source geometry in detail, was used to investigate the dosimetric characteristics of this special CSM3-a 137Cs brachytherapy source. The absolute dose rate distribution in water around this source was calculated and is presented in the form of an along-away table. Comparison of Sievert integral type calculations with Monte Carlo results are discussed.

Fitted dosimetric parameters of high dose-rate 192Ir sources according to the AAPM TG43 formalism

The purpose of this study is to find fitted functional forms to the anisotropy function, F(r, theta), and the radial dose function, g(r), in order to characterize dose-rate distributions around all the high-intensity 192Ir sources currently in use. Dosimetry data are at present available as tables for: the microSelectron HDR ("classic" and "new" design models), the PDR source, and the VariSource HDR source, expressed in terms of the AAPM Task Group No. 43 recommendations. There is only one paper out which introduces a functional form to fit the anisotropy function, but only for symmetric sources with respect to the transverse axis. However, dosimetric data of the HDR and PDR sources mentioned above cannot be reproduced with these functional forms. In our study F(r,theta) and g(r) published data are fitted with functional forms in such a way that appropriate limits are reached for both functions and the maximum fit error approaches the data uncertainty. The average fit error is less than 1% in all cases. These functional forms make handling data easier within the treatment planning system, avoiding the use of tabulated data.

Monte Carlo dosimetry of the Buchler high dose rate 192Ir source

In this study a complete set of dosimetric data is presented for the high dose rate (HDR) source from Amersham used in the Buchler remote afterloading HDR unit. These data have been calculated by means of the Monte Carlo simulation code GEANT taking into account the detailed geometry of the source. Absolute dose rate distributions in water were calculated around this source and are presented as conventional 2D Cartesian look-up tables. All dosimetric quantities recommended by the AAPM Task Group 43 report have been calculated. Quantities determined are: dose rate constant, radial dose function, anisotropy function, anisotropy factor and anisotropy constant. The dose rate distributions of the Buchler HDR source are compared with those of other HDR sources used in brachytherapy, showing that the differences are large in zones near the long source axis due to oblique filtration. These Monte Carlo simulated data in water can be used for clinical applications.

A Monte Carlo investigation of the dosimetric characteristics of the CSM11 137Cs source from CIS

The purpose of this study is to calculate basic dosimetry data for a CSM11 low dose rate 137Cs source in water. This source is widely used in afterloadable dome cylinders designed to homogeneously irradiate the vaginal cuff alone or additional areas of the vagina in hysterectomized patients. In this study, the Monte Carlo simulation code GEANT, incorporating in detail source geometry, is used to investigate the dosimetric characteristics of the source. The calculated data were analyzed using a fitting procedure that is described in detail. Absolute dose rate distributions in water were calculated around this source and are presented as conventional 2D Cartesian lookup tables (classically along-away tables). Also, the dose calculation formalism endorsed by the Interstitial Collaborative Working Group and the AAPM Task Group 43 have been calculated. The calculated dose rate constant for this source is lambda = 1.096 +/- 0.002 cGy h(-1) U(-1). The anisotropy function results in about 50% deviations from isotropy at positions near the long axis of the source. The radial dose function is given as a polynomial that reproduces the calculated data up to 20 cm. Best-fit values of attenuation coefficients suitable for use in Sievert integral calculations have been derived.