A study on Notch signaling in human breast cancer

Breast cancer is one of the leading causes of cancer death in women. The Notch family of proteins plays crucial roles in determining cell fates such as proliferation, differentiation and apoptosis. A role for Notch signaling in human breast cancer has been suggested by the development of adenocarcinomas in the murine mammary gland. However, it is not clear currently whether Notch signaling is frequently expressed and activated in breast cancers. Here we show that Notch signaling is overexpressed and highly activated in breast cancers. More significantly, the attenuation of Notch signaling by gamma-secretase inhibitor can inhibit the proliferation of breast cancer cells by both causing cell cycle arrest and apoptosis. Thus, targeting Notch signaling may be of therapeutic value in breast cancers.     

The endogenous cannabinoid, anandamide, induces cell death in colorectal carcinoma cells: a possible role for cyclooxygenase 2

BACKGROUND AND AIMS: Cyclooxygenase 2 (COX-2) is upregulated in most colorectal cancers and is responsible for metabolism of the endogenous cannabinoid, anandamide, into prostaglandin-ethanolamides (PG-EAs). The aims of this study were to determine whether anandamide and PG-EAs induce cell death in colorectal carcinoma (CRC) cells, and whether high levels of COX-2 in CRC cells could be utilised for their specific targeting for cell death by anandamide. METHODS: We determined the effect of anandamide on human CRC cell growth by measuring cell growth and cell death, whether this was dependent on COX-2 protein expression or enzyme activity, and the potential involvement of PG-EAs in induction of cell death. RESULTS: Anandamide inhibited the growth of CRC cell lines HT29 and HCA7/C29 (moderate and high COX-2 expressors, respectively) but had little effect on the very low COX-2 expressing CRC cell line, SW480. Induction of cell death in HT29 and HCA7/C29 cell lines was partially rescued by the COX-2 selective inhibitor NS398. Cell death induced by anandamide was neither apoptosis nor necrosis. Furthermore, inhibition of fatty acid amide hydrolase potentiated the non-apoptotic cell death, indicating that anandamide induced cell death was mediated via metabolism of anandamide by COX-2, rather than its degradation into arachidonic acid and ethanolamine. Interestingly, both PGE2-EA and PGD2-EA induced classical apoptosis. CONCLUSIONS: These findings suggest anandamide may be a useful chemopreventive/therapeutic agent for colorectal cancer as it targets cells that are high expressors of COX-2, and may also be used in the eradication of tumour cells that have become resistant to apoptosis.     

Intrinsic and acquired resistance to EGFR inhibitors in human cancer therapy

The epidermal growth factor receptor (EGFR) autocrine pathway plays a crucial role in human cancer since it contributes to a number of highly relevant processes in tumor development and progression, including cell proliferation, regulation of apoptotic cell death, angiogenesis and metastatic spread. Among a variety of approaches used to target EGFR signaling, EGFR blocking monoclonal antibodies and small molecular weight EGFR tyrosine kinase compounds have been successfully developed. The results of a large body of preclinical studies and clinical trials suggest that targeting the EGFR could represent a significant contribution to cancer therapy. Both types of agent exert a significant antiproliferative activity when used alone or in combination with conventional antitumor treatments, such as chemotherapy or radiation therapy. Although the advanced clinical development of EGFR blocking drugs demonstrates their efficacy in some human metastatic diseases, such as lung, head and neck and colorectal cancers, the issue of constitutive resistance in a large number of patients and the development of acquired resistance in the responders remains an unexplored subject of investigation. Recent evidence suggests the role of specific activating mutations within the tyrosine kinase domain of EGFR to explain the dramatic responses to small molecule tyrosine kinase inhibitors in a subgroup of lung cancer patients. However, the intrinsic molecular mechanisms of resistance to these drugs are still unclear. This review will focus on the preclinical findings on therapeutic resistance to EGFR targeting agents.     

Long noncoding RNA RP4 functions as a competing endogenous RNA through miR-7-5p sponge activity in colorectal cancer

AIM To investigate the role of long noncoding RNA(lnc RNA) RP4 in colorectal cancer.METHODS Lentivirus-mediated lnc RNA RP4 overexpression and knockdown were performed in the colorectal cancer cell line SW480. Cell proliferation, tumor growth, and early apoptosis were evaluated by a cell counting kit-8 assay, an in vivo xenograft tumor model, and annexin V/propidium iodide staining, respectively. Analysis of the lnc RNA RP4 mechanism involved assessment of the association of its expression with mi R-7-5 p and the SH3 GLB1 gene. Western blot analysis was also performed to assess the effect of lnc RNA RP4 on the autophagy-mediated cell death pathway and phosphatidylinositol-3-kinase(PI3 K)/Akt signaling.RESULTS Cell proliferation, tumor growth, and early apoptosis in SW480 cells were negatively regulated by lnc RNA RP4. Functional experiments indicated that lnc RNA RP4 directly upregulated SH3 GLB1 expression by acting as a competing endogenous RNA(ce RNA) for mi R-7-5 p. This interaction led to activation of the autophagy-mediated cell death pathway and de-repression of PI3 K and Akt phosphorylation in colorectal cancer cells in vivo.CONCLUSION Our results demonstrated that lnc RNA RP4 is a ce RNA that plays an important role in the pathogenesis of colorectal cancer, and could be a potential therapeutic target for colorectal cancer treatment.     

Changes in apoptosis during the development of colorectal cancer: a systematic review of the literature

The development of colorectal cancer is characterised by an accumulation of molecular genetic alterations causing disorders in cell growth, differentiation and apoptosis. Although changes in apoptosis with colorectal cancer development have been studied extensively, a clear consensus of opinion has not yet emerged. In this review, the literature about changes in the frequency and distribution of apoptosis in tissue sections of normal and neoplastic colorectal tissues was reviewed systematically. Using a PUBMED search, 53 relevant articles were identified. Data from these studies are discussed with respect to the following aspects: methods used to detect apoptotic cell death; frequency and locoregional distribution of apoptosis in normal mucosa, adenomas and carcinomas; the correlation between levels of apoptosis and proliferation and the prognostic significance of the degree of apoptosis in colorectal cancer. Possible underlying mechanisms of dysregulation of apoptosis are discussed briefly. Finally, possible therapeutic implications of knowledge of the molecular regulation of apoptosis are discussed and potential options for further research are suggested.     

Pathophysiological mechanisms of death resistance in colorectal carcinoma

Colon cancers develop adaptive mechanisms to survive under extreme conditions and display hallmarks ofunlimited proliferation and resistance to cell death. The deregulation of cell death is a key factor that contri-butes to chemoresistance in tumors. In a physiological context, balance between cell proliferation and death, and protection against cell damage are fundamental processes for maintaining gut epithelial homeostasis. The mechanisms underlying anti-death cytoprotection and tumor resistance often bear common pathways, and although distinguishing them would be a challenge, it would also provide an opportunity to develop advanced anti-cancer therapeutics. This review will outline cell death pathways(i.e., apoptosis, necrosis, and necroptosis), and discuss cytoprotective strategies in normal intestinal epithelium and death resistance mechanisms of colon tumor. In colorectal cancers, the intracellular mechanisms of death resistance include the direct alteration of apoptotic and necroptotic machinery and the upstream events modulating death effectors such as tumor suppressor gene inactivation and pro-survival signaling pathways. The autocrine, paracrine and exogenous factors within a tumor microenvironment can also instigate resistance against apoptotic and necroptotic cell death in colon cancers through changes in receptor signaling or transporter uptake. The roles of cyclooxygenase-2/prostaglandin E2, growth factors, glucose, and bacterial lipopolysaccharides in colorectal cancer will be highlighted. Targeting anti-death pathways in the colon cancer tissue might be a promising approach outside of anti-proliferation and anti-angiogenesis strategies for developing novel drugs to treat refractory tumors.     

Adenoviral gene therapy in gastric cancer： A review

Gastric cancer is one of the most common malignancies worldwide. With current therapeutic approaches the prognosis of gastric cancer is very poor, as gastric cancer accounts for the second most common cause of death in cancer related deaths. Gastric cancer like almost all other cancers has a molecular genetic basis which relies on disruption in normal cellular regulatory mechanisms regarding cell growth, apoptosis and cell division. Thus novel therapeutic approaches such as gene therapy promise to become the alternative choice of treatment in gastric cancer. In gene therapy, suicide genes, tumor suppressor genes and anti-angiogenesis genes among many others are introduced to cancer cells via vectors. Some of the vectors widely used in gene therapy are Adenoviral vectors. This review provides an update of the new developments in adenoviral cancer gene therapy including strategies for inducing apoptosis, inhibiting metastasis and targeting the cancer cells.     

TAT-apoptosis repressor with caspase recruitment domain protein transduction rescues mice from fulminant liver failure

Acute liver failure (ALF) is associated with massive hepatocyte cell death and high mortality rates. Therapeutic approaches targeting hepatocyte injury in ALF are hampered by the activation of distinct stimulus-dependent pathways, mechanism of cell death, and a limited therapeutic window. The apoptosis repressor with caspase recruitment domain (ARC) is a recently discovered death repressor that inhibits both death receptor and mitochondrial apoptotic signaling. Here, we investigated the in vivo effects of ARC fused with the transduction domain of human immunodeficiency virus 1 (HIV-1) (TAT-ARC) on Fas- and tumor necrosis factor (TNF)-mediated murine models of fulminant liver failure. Treatment with TAT-ARC protein completely abrogated otherwise lethal liver failure induced by Fas-agonistic antibody (Jo2), concanavalin A (ConA), or D-galactosamine/lipopolysaccharide (GalN/LPS) administration. Importantly, survival of mice was even preserved when TAT-ARC therapy was initiated in a delayed manner after stimulation with Jo2, ConA, or GalN/LPS. ARC blocked hepatocyte apoptosis by directly interacting with members of the death-inducing signaling complex. TNF-mediated liver damage was inhibited by two independent mechanisms: inhibition of jun kinase (JNK)-mediated TNF-α expression and prevention of hepatocyte apoptosis by inhibition of both death receptor and mitochondrial death signaling. We identified JNK as a novel target of ARC. ARC's caspase recruitment domain (CARD) directly interacts with JNK1 and JNK2, which correlates with decreased JNK activation and JNK-dependent TNF-α production. CONCLUSION: This work suggests that ARC confers hepatoprotection upstream and at the hepatocyte level. The efficacy of TAT-ARC protein transduction in multiple murine models of ALF demonstrates its therapeutic potential for reversing liver failure.     

Cancer therapeutics: Targeting the apoptotic pathway

Apoptosis, a physiological process of programmed cell death, is disrupted in various malignancies. It has been exploited as an anti-cancer strategy traditionally by inducing DNA damage with chemotherapy and radiotherapy. With an increased understanding of the intrinsic and extrinsic pathways of apoptosis in recent years, novel approaches of targeting the apoptotic pathways have been tested in pre-clinical and clinical models. There are several early phase clinical trials investigating the therapeutic role of pro-apoptotic agents, both as single agents and in combination. In this review, we examine such treatment strategies, detailing the various compounds currently under clinical investigation, their potential roles in cancer therapeutics, and discussing approaches to their optimal use in the clinic.     

The research progress of Wnt/β-catenin signaling pathway in colorectal cancer

The Wnt/β-catenin signaling pathway is highly conservative. β-catenin is the key molecule in this pathway. The β-catenin target genes regulate cell proliferation and apoptosis. Since Wnt pathway proteins are distributed on the cell membrane, cytoplasm, and nucleus, inhibiting or activating these pathway proteins presents a novel target for cancer treatment via the Wnt signaling pathway. Studies have found that this pathway plays a significant role in the formation and progression of cancers, particularly colorectal cancer. We summarised the activation and inhibition of the Wnt signaling pathway in tumors, its relationship with the microenvironment and crosstalk with other pathways, and the effect of targeting abnormal Wnt signaling in the treatment of colorectal cancer. Here is to review future targeted therapeutics in colorectal cancer research and implementation.     

A whole-genome RNAi screen identifies an 8q22 gene cluster that inhibits death receptor-mediated apoptosis

Deregulation of apoptosis is a common occurrence in cancer, for which emerging oncology therapeutic agents designed to engage this pathway are undergoing clinical trials. With the aim of uncovering strategies to activate apoptosis in cancer cells, we used a pooled shRNA screen to interrogate death receptor signaling. This screening approach identified 16 genes that modulate the sensitivity to ligand induced apoptosis, with several genes exhibiting frequent overexpression and/or copy number gain in cancer. Interestingly, two of the top hits, EDD1 and GRHL2, are found 50 kb apart on chromosome 8q22, a region that is frequently amplified in many cancers. By using a series of silencing and overexpression studies, we show that EDD1 and GRHL2 suppress death-receptor expression, and that EDD1 expression is elevated in breast, pancreas, and lung cancer cell lines resistant to death receptor-mediated apoptosis. Supporting the relevance of EDD1 and GRHL2 as therapeutic candidates to engage apoptosis in cancer cells, silencing the expression of either gene sensitizes 8q22-amplified breast cancer cell lines to death receptor induced apoptosis. Our findings highlight a mechanism by which cancer cells may evade apoptosis, and therefore provide insight in the search for new targets and functional biomarkers for this pathway.     

Targeting mTOR network in colorectal cancer therapy

The mechanistic target of rapamycin(mTOR)integrates growth factor signals with cellular nutrient and energy levels and coordinates cell growth,proliferation and survival.A regulatory network with multiple feedback loops has evolved to ensure the exquisite regulation of cell growth and division.Colorectal cancer is the most intensively studied cancer because of its high incidence and mortality rate.Multiple genetic alterations are involved in colorectal carcinogenesis,including oncogenic Ras activation,phosphatidylinositol 3-kinase pathway hyperactivation,p 53 mutation,and dysregulation of wnt pathway.Many oncogenic pathways activate the mTOR pathway.mTOR has emerged as an effective target for colorectal cancer therapy.In vitro and preclinical studies targeting the mTOR pathway for colorectal cancer chemotherapy have provided promising perspectives.However,the overall objective response rates in major solid tumors achieved with single-agent rapalog therapy have been modest,especially in advanced metastatic colorectal cancer.Combination regimens of mTOR inhibitor with agents such as cytotoxic chemotherapy,inhibitors of vascular endothelial growth factor,epidermal growth factor receptor and Mitogen-activated protein kinase kinase(MEK)inhibitors are being intensively studied and appear to be promising.Further understanding of the molecular mechanism in mTOR signaling network is needed to develop optimized therapeutic regimens.In this paper,oncogenic gene alterations in colorectal cancer,as well as their interaction with the mTOR pathway,are systematically summarized.The most recent preclinical and clinical anticancer therapeutic endeavors are reviewed.New players in mTOR signaling pathway,such as nonsteroidal anti-inflammatory drug and metformin with therapeutic potentials are also discussed here.     

Towards a new age in the treatment of multiple myeloma

Multiple myeloma (MM) is an incurable disease characterized by the proliferation of end-stage B lymphocytes (plasma cells, PCs). As a consequence of myeloma growth in the bone marrow, a number of signaling pathways are activated that trigger malignant PC proliferation, escape from apoptosis, migration, and invasion. Thanks to new insights into the molecular pathogenesis of MM, novel approaches aimed at targeting these abnormally activated cascades have recently been developed and others are under study. These strategies include the inhibition of membrane receptor tyrosine kinases, inhibition of the proteasome/aggresome machinery, inhibition of histone deacetylases, inhibition of farnesyltransferases, targeting of molecular chaperones, and others. We will herein review and discuss these novel biological approaches with particular emphasis on those based on biochemical pathways which drive cell signaling. By providing the rationale for innovative therapeutic strategies, the above mechanisms represent targets for new compounds being tested in the management of this disease.     

Proteasome inhibitors synergize with tumor necrosis factor-related apoptosis-induced ligand to induce anaplastic thyroid carcinoma cell death

CONTEXT: Anaplastic thyroid carcinoma (ATC) is one of the most aggressive types of cancer characterized by complete refractoriness to multimodal treatment approaches. Therapeutic strategies based on the simultaneous use of proteasome inhibitors and death receptor ligands have been shown to induce apoptosis in several tumor types but have not yet been explored in ATC. OBJECTIVE AND METHODS: The aim of this study was to investigate the ability of the proteasome inhibitor Bortezomib to induce apoptosis in ATC cell lines. Bortezomib was used as a single agent or in combination with TNF-related apoptosis-induced ligand (TRAIL), a member of the TNF family that selectively induces tumor cell apoptosis. The molecular effects of Bortezomib were investigated by analyzing the expression of key regulators of cell cycle and apoptosis and the activation of different apoptotic pathways. RESULTS: Bortezomib induced apoptosis in ATC cells at doses achieved in the clinical setting, differently from conventional chemotherapeutic agents. Simultaneous treatment with low doses of Bortezomib and TRAIL had a synergistic effect in inducing massive ATC cell apoptosis. Bortezomib increased the expression of cytotoxic TRAIL receptors, p21 (WAF/CIP1) and proapoptotic second mitochondria-derived activator of caspases/direct inhibitor of apoptosis binding protein with low pI, and reduced the expression of antiapoptotic mediators such as cellular Fas-associated death domain-like IL-1beta converting enzyme inhibitory protein, Bcl-2, Bcl-X(L), and inhibitor of apoptosis-1, thus resulting in cell death induction through the mitochondrial apoptotic pathway. CONCLUSIONS: The combination of proteasome inhibitors and TRAIL synergizes to induce the destruction of chemoresistant neoplastic thyrocytes and could represent a promising therapeutic strategy for the treatment of anaplastic thyroid carcinoma.     

Combating pancreatic cancer chemoresistance by triggering multiple cell death pathways

Pancreatic cancer is the fourth most common cause of cancer-associated death in western countries, where the incidence and number of deaths are increasing every year. Intrinsic or acquired resistance of tumor cells to chemotherapy agents is the major reason for failure of traditional cancer treatment. Several factors are implicated in this impressive resistance; however, of these, it is important to highlight the extensive cellular heterogeneity of these tumors. This heterogeneity is linked to a wide range of sensitivity that different clones in the same tumor display to chemotherapeutic agents. Accordingly, recent findings in this field have discovered new therapeutic targets in order to develop new combinatory treatments, as well as to induce several cell death pathways and reduce therapy-threshold and likelihood of future resistance. Accordingly, recent research has focused on targeting mitochondria, an organelle with key roles regulating cell death signaling pathways, such as apoptosis, necroptosis, autophagy, ferroptosis, or parthanatos. These findings — identifying new compounds, alone or in combination, that can target pancreatic ductal adenocarcinoma cell resistance — could be the key to future treatments.     

Modeling oncogene addiction using RNA interference

The clinical efficacy of selective kinase inhibitors suggests that some cancer cells may become dependent on a single oncogene for survival. RNAi has been increasingly used to understand such “oncogene addiction” and validate new therapeutic targets. However, RNAi approaches suffer from significant off-target effects that limit their utility. Here, we combine carefully titrated lentiviral-mediated short hairpin RNA knockdown of the epidermal growth factor receptor (EGFR) with heterologous reconstitution by EGFR mutants to rigorously analyze the structural features and signaling activities that determine addiction to the mutationally activated EGFR in human lung cancer cells. EGFR dependence is differentially rescued by distinct EGFR variants and oncogenic mutants, is critically dependent on its heterodimerization partner ErbB-3, and surprisingly, does not require autophosphorylation sites in the cytoplasmic domain. Quantitative “oncogene rescue” analysis allows mechanistic dissection of oncogene addiction, and, when broadly applied, may provide functional validation for potential therapeutic targets identified through large-scale RNAi screens.     

A Mechanistic Review of Cell Death in Alcohol‐Induced Liver Injury

Alcoholic liver disease (ALD) is a major health problem in the United States and worldwide without successful treatments. Chronic alcohol consumption can lead to ALD, which is characterized by steatosis, inflammation, fibrosis, cirrhosis, and even liver cancer. Recent studies suggest that alcohol induces both cell death and adaptive cell survival pathways in the liver, and the balance of cell death and cell survival ultimately decides the pathogenesis of ALD. This review summarizes the recent progress on the role and mechanisms of apoptosis, necroptosis, and autophagy in the pathogenesis of ALD. Understanding the complex regulation of apoptosis, necrosis, and autophagy may help to develop novel therapeutic strategies by targeting all 3 pathways simultaneously.     

A recombinant anti-carcinoembryonic antigen immunoreceptor with combined CD3zeta-CD28 signalling targets T cells from colorectal cancer patients against their tumour cells

BACKGROUND AND AIMS: The prognosis of metastatic colorectal cancer is still poor, raising the need for alternative therapeutic approaches, particularly by manipulating the antitumour immune response. Advanced tumour stages, however, are frequently accompanied by functional T cell defects which may be critical for a T cell based anticancer immunotherapy. The aim of this study was to address whether T cells from colorectal cancer patients with advanced tumour stages can be specifically antigen activated against their autologous tumour cells. METHODS: T cells were isolated from colorectal cancer patients and retrovirally transduced to express a recombinant immunoreceptor that has an extracellular binding domain for carcinoembryonic antigen (CEA) and an intracellular CD3zeta signalling domain with and without CD28 costimulation for T cell activation. RESULTS: Peripheral blood T cells from colorectal cancer patients were successfully engineered to express the anti-CEA immunoreceptor on the cell surface. On coincubation with autologous CEA(+) tumour cells, T cells with anti-CEA immunoreceptor are specifically activated to secrete interferon gamma (IFN-gamma) and to lyse autologous tumour cells whereas T cells without immunoreceptor are not. T cells equipped with combined CD3zeta-CD28 signalling receptor are more efficiently activated to secrete IFN-gamma compared with T cells with CD3zeta signalling receptor. Induction of interleukin 2 secretion on targeting towards autologous tumour cells requires triggering of T cells by the CD3zeta-CD28 costimulatory receptor. CONCLUSIONS: T cells from advanced colorectal cancer patients can be tumour specifically activated with high efficiency by engraftment with a combined CD3zeta-CD28 immunoreceptor to break tolerance against autologous tumour cells.