Antiangiogenic therapy in human gastrointestinal malignancies

Curcumin suppresses invasiveness and vasculogenic mimicry of squamous cell carcinoma of the larynx through the inhibition of JAK-2/STAT-3 signaling pathway

To determine the role of JAK-2/STAT-3 signaling pathway in invasion and vasculogenic mimicry of laryngeal squamous cell carcinoma. HEp-2 cells were treated with 1 or 10 μmol/L curcumin and AG490 (the inhibitor of JAK-2) for 48 h, the invasion and vasculogenic mimicry of tumor cells were tested with Transwell chamber test and tube formation experiment. RT-PCR was used to measure the expression of MMP-2 and VEGF. Western blot assay was employed to determine the expression of JAK-2, STAT3, p-STAT3, MMP-2 and VEGF. Compared to control group，there were less tumor cells permeating membrane and less formed tubes after curcumin or AG490 treatment, RT-PCR showed that the expression of MMP-2 and VEGF at mRNA level were decreased (P < 0.01). Western blotting indicated that the expression of JAK-2, p-STAT3, MMP-2 and VEGF at protein levels were decreased (P < 0.01), while that of STAT-3 protein had no difference among each group (P > 0.05). Immunofluorescence staining demonstrated that the expression of eNOS was down-regulated (P < 0.01). Curcumin and AG490 significantly inhibits invasion and vasculogenic mimicry of laryngeal squamous cell carcinoma in vitro, and JAK-2/STAT-3 signaling pathway promotes above processes.

The molecular basis for the pharmacokinetics and pharmacodynamics of curcumin and its metabolites in relation to cancer

This review addresses the oncopharmacological properties of curcumin at the molecular level. First, the interactions between curcumin and its molecular targets are addressed on the basis of curcumin's distinct chemical properties, which include H-bond donating and accepting capacity of the β-dicarbonyl moiety and the phenylic hydroxyl groups, H-bond accepting capacity of the methoxy ethers, multivalent metal and nonmetal cation binding properties, high partition coefficient, rotamerization around multiple C-C bonds, and the ability to act as a Michael acceptor. Next, the in vitro chemical stability of curcumin is elaborated in the context of its susceptibility to photochemical and chemical modification and degradation (e.g., alkaline hydrolysis). Specific modification and degradatory pathways are provided, which mainly entail radical-based intermediates, and the in vitro catabolites are identified. The implications of curcumin's (photo)chemical instability are addressed in light of pharmaceutical curcumin preparations, the use of curcumin analogues, and implementation of nanoparticulate drug delivery systems. Furthermore, the pharmacokinetics of curcumin and its most important degradation products are detailed in light of curcumin's poor bioavailability. Particular emphasis is placed on xenobiotic phase I and II metabolism as well as excretion of curcumin in the intestines (first pass), the liver (second pass), and other organs in addition to the pharmacokinetics of curcumin metabolites and their systemic clearance. Lastly, a summary is provided of the clinical pharmacodynamics of curcumin followed by a detailed account of curcumin's direct molecular targets, whereby the phenotypical/biological changes induced in cancer cells upon completion of the curcumin-triggered signaling cascade(s) are addressed in the framework of the hallmarks of cancer. The direct molecular targets include the ErbB family of receptors, protein kinase C, enzymes involved in prostaglandin synthesis, vitamin D receptor, and DNA.

Advances in pancreatic cancer detection

Pancreatic cancer represents a major challenge for research studies and clinical management. No specific tumor marker for the diagnosis of pancreatic cancer exists. Therefore, extensive genomic, transcriptomic, and proteomic studies are being developed to identify candidate markers for use in high-throughput systems capable of large cohort screening. Understandably, the complex pathophysiology of pancreatic cancer requires sensitive and specific biomarkers that can improve both early diagnosis and therapeutic monitoring. The lack of a single diagnostic marker makes it likely that only a panel of biomarkers is capable of providing the appropriate combination of high sensitivity and specificity. Biomarker discovery using novel technology can improve prognostic upgrading and pinpoint new molecular targets for innovative therapy.

Curcumin inhibits VEGF-mediated angiogenesis in human intestinal microvascular endothelial cells through COX-2 and MAPK inhibition

BACKGROUND

Angiogenesis, the growth of new blood vessels, is a critical homeostatic mechanism which regulates vascular populations in response to physiological requirements and pathophysiological demand, including chronic inflammation and cancer. The importance of angiogenesis in gastrointestinal chronic inflammation and cancer has been defined, as antiangiogenic therapy has demonstrated benefit in models of inflammatory bowel disease and colon cancer treatment. Curcumin is a natural product undergoing evaluation for the treatment of chronic inflammation, including inflammatory bowel disease (IBD). The effect of curcumin on human intestinal angiogenesis is not defined.

METHODS

The antiangiogenic effect of curcumin on in vitro angiogenesis was examined using primary cultures of human intestinal microvascular endothelial cells (HIMECs), stimulated with vascular endothelial growth factor (VEGF).

RESULTS

Curcumin inhibited proliferation, cell migration and tube formation in HIMECs induced by VEGF. Activation of HIMECs by VEGF resulted in enhanced expression of cyclo-oxygenase-2 (COX-2) mRNA, protein and prostaglandin E(2) (PGE(2)) production. Pretreatment of HIMECs with 10 microM curcumin as well as 1 microM NS398, a selective inhibitor of COX-2, resulted in inhibition of COX-2 at the mRNA and protein level and PGE(2) production. Similarly COX-2 expression in HIMECs was significantly inhibited by Jun N-terminal kinase (JNK; SP600125) and p38 mitogen-activated protein kinase (MAPK; SB203580) inhibitors and was reduced by p44/42 MAPK inhibitor (PD098059).

CONCLUSIONS

Taken together, these data demonstrate an important role for COX-2 in the regulation of angiogenesis in HIMECs via MAPKs. Moreover, curcumin inhibits microvascular endothelial cell angiogenesis through inhibition of COX-2 expression and PGE(2) production, suggesting that this natural product possesses antiangiogenic properties, which warrants further investigation as adjuvant treatment of IBD and cancer.

Current status and future of chemotherapy and biochemotherapy in gastroesophageal cancers

A number of advances recently have been made in the chemotherapeutic treatment of gastroesophageal cancer. Perioperative combination chemotherapy based on cisplatin and 5-fluorouracil (5-FU) improves the prognosis of patients with stage II and stage III disease. Preoperative initiation of chemotherapy seems to be essential for achieving this result, according to studies performed in the West. On the other hand, Japanese investigators demonstrated that postoperative administration of oral fluoropyrimidine prodrugs can substantially improve the prognosis of patients with curatively resected gastric cancer. The addition of docetaxel to cisplatin and 5-FU has significantly improved response rate, time to progression, and overall survival in patients treated for advanced gastric cancer, as well as prolonging time to definitive worsening of global health status and Karnofsky performance status. Due to increased hematologic toxicity with this regimen, particularly neutropenic infections, careful patient selection and optimal supportive care, including prophylactic granulocyte colonystimulating factor, are required. Alternative schedules are being investigated that could improve the tolerability of docetaxel plus platinum/fluoropyrimidine combination regimens. Further improvements in outcome may be achieved when even more active chemotherapy combinations including docetaxel are systematically implemented into the preoperative treatment of locally advanced gastroesophageal cancers. Initial results with biologic targeted agents in this setting are promising. Pathways currently under investigation include the epidermal growth factor receptors Her-1 and Her-2, vascular endothelial growth factor, and the epithelial cell adhesion molecule EpCAM. It is hoped that targeting these pathways will further increase the efficacy of biochemotherapy of gastroesophageal cancer. Evaluating early response to biochemotherapy using metabolic imaging is a novel approach that may allow for tailoring systemic therapy to individual tumor biology. A deeper understanding of the relevant pathognomonic molecular patterns and signatures in individual tumors may facilitate faster drug development and permit more accurate selection of active therapies in the future.