Anti-angiogenic strategies in gastrointestinal malignancies

Casticin induced apoptotic cell death and altered associated gene expression in human colon cancer colo 205 cells

Casticin, a polymethoxyflavone, derived from natural plant Fructus Viticis exhibits biological activities including anti-cancer characteristics. The anti-cancer and alter gene expression of casticin on human colon cancer cells and the underlying mechanisms were investigated. Flow cytometric assay was used to measure viable cell, cell cycle and sub-G1 phase, reactive oxygen species (ROS) and Ca²⁺ productions, level of mitochondria membrane potential (ΔΨ_m ) and caspase activity. Western blotting assay was used to detect expression of protein level associated with cell death. Casticin induced cell morphological changes, decreased cell viability and induced G2/M phase arrest in colo 205 cells. Casticin increased ROS production but decreased the levels of ΔΨ_m , and Ca²⁺ , increased caspase-3, -8, and -9 activities. The cDNA microarray indicated that some of the cell cycle associated genes were down-regulated such as cyclin-dependent kinase inhibitor 1A (CDKN1A) (p21, Cip1) and p21 protein (Cdc42/Rac)-activated kinase 3 (PAK3). TNF receptor-associated protein 1 (TRAP1), CREB1 (cAMP responsive element binding protein 1) and cyclin-dependent kinase inhibitor 1B (CDKN1B) (p27, Kip1) genes were increased but matrix metallopeptidase 2 (MMP-2), toll-like receptor 4 (TLR4), PRKAR2B (protein kinase, cAMP-dependent, regulatory, type II, bet), and CaMK4 (calcium/calmodulin-dependent protein kinase IV) genes were inhibited. Results suggest that casticin induced cell apoptosis via the activation of the caspase- and/or mitochondria-dependent signaling cascade, the accumulation of ROS and altered associated gene expressions in colo 205 human colon cancer cells.

FOXP3 and CEACAM6 expression and T cell infiltration in the occurrence and development of colon cancer

The transcription factor forkhead box P3 (FOXP3) is involved in immune cell regulation, and carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is an adhesion molecule of the immunoglobulin superfamily. These two genes are associated with cancer progression. In the current study, colon tissue specimens from 78 cases of colon cancer (including 40 of stage I-II and 38 of stage III-IV), 30 cases of colonic adenoma and 12 healthy controls were collected from the First Affiliated Hospital of Soochow University between January 2010 and December 2011. The expression of cluster of differentiation (CD) 3, CD4, CD8, CD45RO, CEACAM6 and FOXP3 in colon tissues was examined by immunohistochemical analysis. In addition, a reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assay, based on SYBR Green I, was used to detect CD3, CD4, CD8, CD45RO, CEACAM6 and FOXP3 mRNA levels in the paraffin block specimens. CD3⁺, CD8⁺ and CD45RO⁺ T cell infiltrations in colonic adenoma were significantly higher than in normal colonic mucosa (P<0.001, P=0.001 and P<0.001, respectively). However, CD3⁺, CD8⁺ and CD45RO⁺ lymphocytes in stage III-IV colon cancer tissues were lower than in normal control tissues (P=0.015, P=0.002 and P=0.041, respectively); consistently, CD3⁺, CD4⁺, CD8⁺ and CD45RO⁺ lymphocytes in stage III-IV tissues were even more markedly lower compared with adenoma (P=0.001, P<0.001, P<0.001 and P<0.001, respectively). Similarly, CD3⁺, CD8⁺ and CD45RO⁺ T cell infiltration was lower in stage I-II cancer tissues compared with adenoma (P=0.001, P<0.001 and P<0.001). CD3⁺, CD4⁺, CD8⁺ and CD45RO⁺ T cell infiltrations were also significantly higher in stage I-II compared with stage III-IV cancer tissues (P<0.001, P=0.045, P<0.001 and P<0.001, respectively). CEACAM6 was found to gradually increase from normal colon tissue to adenoma and cancer tissue. FOXP3 was expressed more highly in stage I-II compared with normal tissues (P=0.014), and was even higher in stage III-IV (P<0.001). These results were verified using RT-qPCR, which yielded almost identical results. In summary, the current study demonstrates that FOXP3, CEACAM6 and T cell infiltration are significantly associated with the occurrence and progression of colon cancer, and that immune reactions vary between different stages of colon cancer development.

Combined therapy for diabetic macular edema

Diabetic macular edema (DME) is the main cause of visual impairment in diabetic patients. Macular edema within 1 disk diameter of the fovea is present in 9% of the diabetic population. The management of DME is complex and often multiple treatment approaches are needed. This review demonstrates the benefits of intravitreal triamcinolone, bevacizumab and ranibizumab as adjunctive therapy to macular laser treatment in DME. The published results indicate that intravitreal injections of these agents may have a beneficial effect on macular thickness and visual acuity, independent of the type of macular edema that is present. Therefore, pharmacotherapy could complement focal/grid laser photocoagulation in the management of DME. For this review, we performed a literature search and summarized recent findings regarding combined therapy for DME.

Clinical implications of DLL4 expression in gastric cancer

BACKGROUND

Delta-like ligand 4 (DLL4)-Notch signaling plays a key role in tumor neovascular development and angiogenesis during tumor growth. The clinical significance of DLL4 expression in gastric cancer has not been clarified.

METHODS

Gastric cancer cell lines and 180 gastric cancer patients were enrolled. DLL4 expression in gastric cancer cells and stroma was identified and evaluated immunohistochemically. The association between DLL4 and clinicopathological factors was also assessed.

RESULTS

DLL4 expression was identified in the cellular membrane and cytoplasm of gastric cancer cells by immunoblotting and immunohistochemical staining. DLL4 positivity in cancer cells and stroma was found in 88 (48%) and 41 (22%) of the 180 gastric cancer patients respectively. Both cancer and stromal DLL4 expression significantly correlated with more advanced tumor depth, nodal involvement, and lymphatic and venous invasion. A strongly positive association between cancerous and stromal DLL4 expression was identified (p < 0.01). Both cancerous and stromal DLL4 expression were prognostic markers in gastric cancer as determined by univariate analysis.

CONCLUSIONS

Cancerous and stromal DLL4 expression was found in 48% and 22% in gastric cancer, and significantly affected postoperative clinical outcomes. Cancerous and stromal DLL4 expression may be an effective target of anti-DLL4 treatment in gastric cancer.

Molecularly targeted therapy for gastric cancer: current status and future prospects

Gastric cancer remains the second leading cause of cancer death worldwide. Currently, chemotherapy is the mainstay of treatment for patients with metastatic gastric cancer. Although new chemotherapeutic regimens improved the survival of patients with advanced gastric cancer, the median survival in all randomized trials remains unsatisfactory. Novel treatment options are urgently needed to improve the outcome of patients with advanced gastric cancer. Understanding the molecular pathways that characterize cell growth, apoptosis, angiogenesis and invasion has enabled us to use new approaches to treat this disease in clinical situations. The aim of this review is to summarize the most recent publications on targeted therapies for advanced gastric cancer.

Antitumor/antiestrogenic effect of the chemokine interferon inducible protein 10 (IP-10) involves suppression of VEGF expression in mammary tissue

Vascular endothelial growth factor (VEGF) promotes angiogenesis in a number of tumor model systems. We reported previously that estrogen supports the growth of CCL-51 cell-based mammary tumors in mice, which could be blocked with specific chemokines. We investigated whether promotion of tumor growth by estrogen, and suppression of tumor growth by chemokines, was associated with VEGF protein expression. Female C3H mice were treated with vehicle, estradiol, or with one of several chemokines for 72 h. The presence of VEGF in mammary tissue samples was detected and quantified by sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting using antimurine VEGF antibodies. Estrogen significantly increased mammary VEGF expression. Cotreatment with tamoxifen or the chemokine interferon-inducible protein-10 (IP-10) suppressed the action estrogen on VEGF expression. CCL-51 tumor cells were placed into mammary tissue of C3H mice. Mice were treated every 72-h with either vehicle or estradiol, in the presence or absence of IP-10 for 21 days. Estrogen supported CCL-51 tumor growth, with an average of 2.3 tumors present/animal. Cotreatment of mice with estrogen and IP-10 resulted in significantly lower numbers of tumors in mammary tissue in comparison to animals treated with estrogen alone. VEGF levels in mammary tissue and tumors of IP-10 and estrogen cotreated mice were 40-50% less than those detected in mammary tissue of estrogen-treated mice. Our results suggest that estrogenic support of CCL-51 mammary tumor growth is related to increased VEGF expression, and that the inhibitory action of IP-10 may be related to suppressing VEGF levels in mammary tissue.

Critical role and regulation of transcription factor FoxM1 in human gastric cancer angiogenesis and progression

The mammalian forkhead box (Fox) transcription factor FoxM1b is implicated in tumorigenesis. However, the presence of expression and role of FoxM1b in gastric cancer remain unknown. Therefore, we investigated FoxM1b expression in 86 cases of primary gastric cancer and 57 normal gastric tissue specimens. We further investigated the underlying mechanisms of altered FoxM1b expression in and the effect of this altered expression on gastric cancer growth and metastasis using in vitro and animal models of gastric cancer. We found weak expression of FoxM1b protein in the mucous neck region of gastric mucosa, whereas we observed strong staining for FoxM1b in tumor cell nuclei in various gastric tumors and lymph node metastases. A Cox proportional hazards model revealed that FoxM1b expression was an independent prognostic factor in multivariate analysis (P < 0.001). Experimentally, overexpression of FoxM1b by gene transfer significantly promoted the growth and metastasis of gastric cancer cells in orthotopic mouse models, whereas knockdown of FoxM1b expression by small interfering RNA did the opposite. Promotion of gastric tumorigenesis by FoxM1b directly and significantly correlated with transactivation of vascular endothelial growth factor expression and elevation of angiogenesis. Given the importance of FoxM1b to regulation of the expression of genes key to cancer biology overall, dysregulated expression and activation of FoxM1b may play important roles in gastric cancer development and progression.

Current status and recent developments in molecular targeted therapy against gastric cancer

Gastric cancer (GC) is one of the most common malignancies of the digestive system and is a major cause of cancer death in China. Recent improvements in both surgical techniques and adjuvant/neoadjuvant chemotherapy, radiotherapy or both have increased the survival rate of patients with early-stage disease. However, most patients with GC have advanced disease at diagnosis. Thus, despite recent advances, these patients still do poorly. Understanding the molecular pathways that characterize cell growth, cell cycle, apoptosis, angiogenesis and invasion has enabled us to use new approaches to treat this disease in clinical situations. These therapeutic strategies include epidermal growth factor receptor inhibitors, angiogenesis inhibitors, cell cycle inhibitors, apoptosis promoters and matrix metalloproteinase inhibitors. This review presents a brief introduction to the current status and advancement of molecular targeted therapies in the treatment of GC.

Stem cell factor/c-kit receptor signaling enhances the proliferation and invasion of colorectal cancer cells through the PI3K/Akt pathway

In this study, we examined the role of c-kit receptor (KIT) signal transduction on the proliferation and invasion of colorectal cancer cells. We found that c-kit was expressed in 2 colorectal cancer cell lines as determined by RT-PCR, Western blot, and flow cytometry. In KIT-positive lines, KIT was activated by stem cell factor (SCF). SCF enhanced cellular proliferation of positive lines as demonstrated by the WST-1 proliferation assay. Furthermore, SCF enhanced the invasive ability of KIT-positive cell lines. SCF stimulation upregulated p44/42 mitogen-activated protein kinase (MAPK) and Akt as shown by Western blot. We examined the roles played by p44/42 MAPK and phosphatidylinositol 3-kinase (PI3K)/Akt pathways in proliferation and invasion. PI3K/Akt activity strongly correlated with proliferation and invasion and p44/42 MAPK was correlated with only invasion. In conclusion, the SCF-enhanced proliferation and invasion of KIT-positive colorectal cancer cells is achieved mainly through the PI3K/Akt pathway.

Non-fucosylated therapeutic antibodies as next-generation therapeutic antibodies

Most of the existing therapeutic antibodies that have been licensed and developed as medical agents are of the human IgG1 isotype, the molecular weight of which is approximately 150 kDa. Human IgG1 is a glycoprotein bearing two N-linked biantennary complex-type oligosaccharides bound to the antibody constant region (Fc), in which the majority of the oligosaccharides are core fucosylated, and it exercises the effector functions of antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity through the interaction of the Fc with either leukocyte receptors (FcgammaRs) or complement. Recently, therapeutic antibodies have been shown to improve overall survival as well as time to disease progression in a variety of human malignancies, such as breast, colon and haematological cancers, and genetic analysis of FcgammaR polymorphisms of cancer patients has demonstrated that ADCC is a major antineoplasm mechanism responsible for clinical efficacy. However, the ADCC of existing licensed therapeutic antibodies has been found to be strongly inhibited by serum due to nonnpecific IgG competing for binding of the therapeutics to FcgammaRIIIa on natural killer cells, which leads to the requirement of a significant amount of drug and very high costs associated with such therapies. Moreover, enhanced ADCC of non-fucosylated forms of therapeutic antibodies through improved FcgammaRIIIa binding is shown to be inhibited by the fucosylated counterparts. In fact, non-fucosylated therapeutic antibodies, not including the fucosylated forms, exhibit the strongest and most saturable in vitro and ex vivo ADCC among such antibody variants with improved FcgammaRIIIa binding as those bearing naturally occurring oligosaccharide heterogeneities and artificial amino acid mutations, even in the presence of plasma IgG. Robust stable production of completely non-fucosylated therapeutic antibodies in a fixed quality has been achieved by the generation of a unique host cell line, in which the endogenous alpha-1,6-fucosyltransferase (FUT8) gene is knocked out. Thus, the application of non-fucosylated antibodies is expected to be a promising approach as next-generation therapeutic antibodies with improved efficacy, even when administrated at low doses in humans in vivo. Clinical trials using non-fucosylated antibody therapeutics are underway at present.

Colon cancer and the immune system: The role of tumor invading T cells

Colon cancer is still one of the leading causes of cancer death worldwide. Although the host immune system has been shown to react against tumor cells, mainly through tumor infiltrating lymphocytes and NK cells, tumor cells may utilize different ways to escape anti-tumor immune response. Tumor infiltration of CD8+ and CD4+ (T-bet+) effector T cells has been attributed to a beneficial outcome, and the enhancement of T cell activation through T cell receptor stimulation and co-stimulatory signals provides promising strategies for immunotherapy of colon cancer. Growing evidence supports a role for the Fas/FasL system in tumor immunology, although the mechanisms and consequences of FasL activation in colon cancer are not completely understood. In animal models, depletion of regulatory T cells (CD4+ CD25+ T cells) can enhance the anti-tumor immune response under certain conditions. Taken together, recent insights in the immune reaction against colon carcinoma have provided new approaches to immunotherapy, although much remains to be learned about the exact mechanisms.