The role of CD95 system in chemotherapy

NGAL Mediates Anaplastic Thyroid Carcinoma Cells Survival Through FAS/CD95 Inhibition

Neutrophil gelatinase-associated lipocalin (NGAL), a siderophore-mediated iron binding protein, is highly expressed in human anaplastic thyroid carcinomas (ATCs) where it plays pleiotropic protumorigenic roles including that of a prosurvival protein. Here we show that NGAL inhibits FAS/CD95 death receptor to control ATC cell survival. FAS/CD95 expression in human specimens from patients with ATC and in ATC-derived cell lines negatively correlate with NGAL expression. Silencing of NGAL in ATC cells leads to FAS/CD95 upregulation, whereas NGAL overexpression determines the opposite effect. As a result, an agonist anti-FAS/CD95 antibody induces cell death in NGAL-silenced cells while it is ineffective on NGAL-overexpressing cells. Interestingly, the inhibitory activity of NGAL on FAS/CD95 is due to its iron carrier property given that perturbing iron homeostasis of NGAL-proficient and -deficient ATC cells directly influences FAS/CD95 expression. Accordingly, conditioned media containing a mutant form of NGAL unable to bind siderophores cannot rescue cells from FAS/CD95-dependent death, whereas NGAL wild type-containing conditioned media abolish the effects of the agonist antibody. We also find that downregulation of FAS/CD95 expression is mediated by iron-dependent NGAL suppression of p53 transcriptional activity. Our results indicate that NGAL contributes to ATC cell survival by iron-mediated inhibition of p53-dependent FAS/CD95 expression and suggest that restoring FAS/CD95 by NGAL suppression could be a helpful strategy to kill ATC cells.

The Effect of p53-R249S on the Suppression of Hepatocellular Carcinoma Cells Survival Induced by Podophyllum Derivatives

BACKGROUND

Hepatocellular Carcinoma (HCC), the second leading cause of cancer-related mortality with over half a million new cases diagnosed annually in the world, accounts for nearly 70% of cancer deaths in parts of Asia and Africa. Podophyllum, one of the important members of the lignane class of natural products derived from plants in Podophyllum peltatum L., has been shown to suppress tumor growth in various cancers. However, the effects of Podophyllum compounds on HCC and the mechanisms for its tumor-suppressive function remain unknown.

METHODS

A molecular docking study was employed to the analysis of the interaction between compounds and their targeted proteins. Cell proliferation was measured by MTT assay. Western blot analysis was used to evaluate protein expression. qRT-PCR was performed to assess RNA expression.

RESULTS

Molecular docking analysis was consistent with the beneficial effect of fluorine atom substituent in the 3-position of 2-aminopyridine in our previous study. Also, P-3F and D-3F displayed the most potent cytotoxicities against PLC/PRF/5 with p53-R249S and weakest inhibition of L02 (normal liver cell) growth. However, these derivatives had no effect on the suppression of HepG2 (wild-type p53) and Hep3B (p53-null) proliferation significantly. Further study showed that both compounds increase γ-H2AX expression in PLC/PRF/5 cell, along with repression of the c-Myc activation, purportedly by induction of p53 level and transcriptional activation.

CONCLUSION

The results suggested that podophyllum derivatives containing fluorine atom in the 3-position of 2- aminopyridine could inhibit the growth of HCC harboring p53-R249S by restoring the activity of p53 with decreasing the level of c-Myc.

Artichoke extracts in cancer therapy: do the extraction conditions affect the anticancer activity?

Background

Artichoke is an edible plant that is grown in the Mediterranean region and is known for its antimicrobial, antifungal, antibacterial, antioxidant and anticancer activities. Different artichoke extraction methods can impressively affect the nature as well as the yield of the extracted components.

Main body

The different methods of artichoke extraction and the influence of the extraction conditions on the extraction efficiency are summarized herein. In addition, cancer causalities and hallmarks together with the molecular mechanisms of artichoke active molecules in cancer treatment are also discussed. Moreover, a short background is given on the common types of cancer that can be treated with artichoke extracts as well as their pathogenesis. A brief discussion of the previous works devoted to the application of artichoke extracts in the treatment of these cancers is also given.

Conclusion

This review article covers the extraction methods, composition, utilization and applications of artichoke extracts in the treatment of different cancers.

CD49b, CD87, and CD95 Are Markers for Activated Cancer-Associated Fibroblasts Whereas CD39 Marks Quiescent Normal Fibroblasts in Murine Tumor Models

Fibroblasts are thought to be key players in the tumor microenvironment. Means to identify and isolate fibroblasts as well as an understanding of their cancer-specific features are essential to dissect their role in tumor biology. To date, the identification of cancer-associated fibroblasts is widely based on generic markers for activated fibroblasts in combination with their origin in tumor tissue. This study was focused on a deep characterization of the cell surface marker profile of cancer-associated fibroblasts in widely used mouse tumor models and defining aberrant expression profiles by comparing them to their healthy counterparts. We established a generic workflow to isolate healthy and cancer-associated fibroblasts from solid tissues, thereby reducing bias, and background noise introduced by non-target cells. We identified CD87, CD44, CD49b, CD95, and Ly-6C as cancer-associated fibroblast cell surface markers, while CD39 was identified to mark normal fibroblasts from healthy tissues. In addition, we found a functional association of most cancer-related fibroblast markers to proliferation and a systemic upregulation of CD87, and CD49b in tumor-bearing mice, even in non-affected tissues. These novel markers will facilitate the characterization of fibroblasts and shed further light in their functions and implication in cancer progression.

Targeting cell death in tumors by activating caspases

Cytotoxic approaches to killing tumor cells, such as chemotherapeutic agents, gamma-irradiation, suicide genes or immunotherapy, have been shown to induce cell death through apoptosis. The intrinsic apoptotic pathway is activated following treatment with cytotoxic drugs, and these reactions ultimately lead to the activation of caspases, which promote cell death in tumor cells. In addition, activation of the extrinsic apoptotic pathway with death-inducing ligands leads to an increased sensitivity of tumor cells toward cytotoxic stimuli, illustrating the interplay between the two cell death pathways. In contrast, tumor resistance to cytotoxic stimuli may be due to defects in apoptotic signaling. As a result of their importance in killing cancer cells, a number of apoptotic molecules are implicated in cancer therapy. The knowledge gleaned from basic research into apoptotic pathways from cell biological, structural, biochemical, and biophysical approaches can be used in strategies to develop novel compounds that eradicate tumor cells. In addition to current drug targets, research into molecules that activate procaspase-3 directly may show the direct activation of the executioner caspase to be a powerful therapeutic strategy in the treatment of many cancers.

Early prediction of therapy response in patients with acute myeloid leukemia by nucleosomal DNA fragments

BACKGROUND

Elevated levels of nucleosomal DNA fragments can be detected in plasma and sera of patients with malignant diseases.

METHODS

We investigated the course of nucleosomal DNA, thymidine kinase, lactate dehydrogenase and leukocytes in sera of 25 patients with acute myeloid leukemia during the first cycle of induction chemotherapy and tested their power to distinguish between patients with complete remission and those with no remission.

RESULTS

Almost all patients showed strongly decreasing levels of nucleosomal DNA during the first week, in some cases after initial peaks. In overall analysis of variance, DNA levels could clearly distinguish between patients with complete remission, who had higher DNA values, and those with insufficient response (p = 0.017). The area under the curve of DNA values of days 2-4 after start of therapy (AUC 2-4) discriminated between both groups with a sensitivity of 56% at a specificity of 100%. Further, pretherapeutic levels and AUC 2-4 of nucleosomal DNA correlated significantly with blast reduction after 16 days. A tendency to higher levels in patients with complete response was also found for thymidine kinase, lactate dehydrogenase and leukocytes, however the difference did not reach the level of significance (p = 0.542, p = 0.260, and p = 0.144, respectively).

CONCLUSION

Our results indicate that nucleosomal DNA fragments are valuable markers for the early prediction of therapeutic efficacy in patients with acute myeloid leukemia.

L’apoptose hépatique

Apoptosis or programmed cell death occurs in the liver as in other organs. In the normal state it is not a frequent mode of hepatic cell destruction. Morphological and biochemical characteristics of liver cell apoptosis do not differ from what is observed in other cells. The Fas receptor pathway, a frequent hepatic apoptotic pathway among various others, involves intra-cellular signals amplified by mitochondria. Although hepatic apoptosis may occur by following several others pathways, Fas, which is abundantly expressed in the plasma membrane of hepatocytes, is very often involved in hepatocyte demise during B or C viral hepatitis irrespective of their clinical form, alcoholic hepatitis, cholestasis due to accumulation of hepatic biliary salts, or certain types of drug-induced hepatitis. Fas is also probably responsible for the death of biliary cells in primary biliary cirrhosis. In contrast one of the causes of resistance to apoptosis of hepatic cancerous cells could be related to an alteration of the Fas receptor. This is why much experimental work is presently performed to achieve inhibition of the Fas receptor either at the mRNA level or at the level of Fas-inductible proteolytic enzymes called caspases. One perspective is a specific treatment of apoptosis as an adjuvant treatment of liver diseases.

Paclitaxel/Taxol® sensitivity in human renal cell carcinoma is not determined by the p53 status

In this study, we analyzed the role of the p53 status for paclitaxel/Taxol sensitivity in renal cell carcinomas (RCCs) of the clear cell type. Using immunohistochemistry, nuclear p53 accumulation could not be correlated to the paclitaxel/Taxol sensitivity. DNA sequencing detected a p53 gene mutation in two out of eight RCC cell lines, i.e. in exon 8 (cell line clearCa-6), and in exon 9 (cell line clearCa-5). No correlation, however, was found between the p53 status of our RCC cell lines and their paclitaxel/Taxol sensitivity as indicated by the IC50 values. However, paclitaxel-induced growth inhibition in paclitaxel-sensitive RCC cell lines was accompanied by an increase in apoptosis, irrespective of their p53 status. Although CD95 up-regulation was observed in renal cell carcinoma with wild-type p53 upon paclitaxel treatment, paclitaxel-induced apoptosis itself is triggered independently from the CD95 system. In conclusion, the p53 status cannot predict paclitaxel/Taxol sensitivity in RCC cell lines of the clear cell type.

FR901228 induces tumor regression associated with induction of Fas ligand and activation of Fas signaling in human osteosarcoma cells

We investigated the antitumor effects of FR901228, a HDAC inhibitor, on human osteosarcoma cells, in vitro and in vivo to explore its possible utility in the treatment of pediatric bone cancers. FR901228 caused marked growth inhibition with a 50% inhibitory concentration of 1.2-7.3 nM and induction of apoptosis in all eight osteosarcoma cell lines tested. These effects of FR901228 were also observed in vivo xenograft models on BALB/c nude mice, and treatment with 5.6 mg/kg/day resulting in a >70% reduction in the mean final tumor volume compared with the mean initial tumor volume. TUNEL assays demonstrated extensive apoptosis in tumor sections of mice treated with FR901228. Induction of apoptosis was preceded by increased expression of Fas ligand (FasL) mRNA, resulting in expression of membrane-bound FasL, which was followed by sequential activation of caspase-8 and -3. The level of apoptosis induction was reduced using a neutralizing anti-FasL antibody and overexpression of either the dominant-negative FADD or the viral FLICE inhibitory protein. Furthermore, treatment with a suboptimal dose of FR901228 greatly sensitized osteosarcoma cells to agonistic anti-Fas antibody-mediated apoptosis. These findings suggest that FR901228 is a highly promising antitumor agent against osteosarcoma, inducing apoptosis by the activation of the Fas/FasL system.

Apoptosis in hematological disorders

Apoptosis, the cell's intrinsic death program, plays a critical role in the regulation of tissue homeostasis, especially in cell systems with a high turnover rate such as hematopoietic cells. Imbalances between proliferation and cell death may result in premature death, uncontrolled polyclonal or monoclonal expansion or tumor formation. Also, cytotoxic therapy and immunotherapy of leukemia and lymphoma predominantly mediates cell death through induction of apoptosis. Understanding the molecular events by which tumor cells evade apoptotic deletion and which induce apoptosis by cytotoxic therapies, have provided a paradigm to link normal growth control, malignant transformation and response to therapy.

Drug resistance does not correlate with resistance to Fas-mediated apoptosis

Recent reports have correlated multidrug resistance (MDR) and P-glycoprotein expression with decreased Fas expression and resistance to Fas-mediated apoptosis. We report the MRP-overexpressing MDR subline CEM/E1000 has the same Fas expression (MFI 74.3 +/- 0.7) as the parental CCRF-CEM T-cell leukaemia cells (MFI 70.0 +/- 3.6; P>0.05), and that the level of apoptosis induced by anti-Fas antibody or drug was similar in both cell lines. Further the P-glycoprotein-expressing CEM/VLB(100) subline of the CCRF-CEM cells showed increased Fas expression (MFI 114.8 +/- 3.6; P<0.001) and no resistance to Fas-mediated apoptosis. This questions the hypothesis that selection of drug resistance results in resistance to Fas-mediated apoptosis, with important implications for the rational use of immunotherapy in the treatment of drug resistant cancer.