Mutation analysis and mRNA expression of trail-receptors in human breast cancer

Genetic association between TRAIL-R1 Thr209Arg and cancer susceptibility

We aimed to determine the indecisive association between tumor necrosis factor-related apoptosis-inducing ligand receptor 1 (TRAIL-R1) Thr209Arg polymorphism and inherited susceptibility to cancer. A meta-analysis combining data on 9,517 individuals was performed to assess the association between TRAIL-R1 Thr209Arg and cancer incidence. The summary ORs with 95% CI calculated with the fixed effects model suggested that Thr209Arg was not significantly associated with cancer susceptibility (homozygous model: OR 0.98, 95% CI 0.88–1.09; heterozygous model: OR 0.95, 95% CI 0.87–1.04; allele frequency model: OR 0.99, 95% CI 0.94–1.05; dominant model: OR 0.98, 95% CI 0.91–1.05; recessive model: OR 1.01, 95% CI 0.92–1.10). Stratified analysis by ethnicity and cancer type yielded similar null associations. These statistical data suggest that Thr209Arg in exon 4 of the TRAIL-R1 gene may not represent a modifier of susceptibility to cancer.

Genetic variants in the tumor necrosis factor-related apoptosis-inducing ligand and death receptor genes contribute to susceptibility to bladder cancer

AIM

The aim of this study was to evaluate the role of polymorphisms of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and death receptor (DR4) genes in bladder cancer susceptibility in a Turkish population.

MATERIALS AND METHODS

The study group included 91 bladder cancer patients, while the control group comprised 139 individuals with no evidence of malignancy. Gene polymorphisms of TRAIL C1595T (rs1131580) and DR4 C626G (rs4871857) were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.

RESULTS

The frequency of the TRAIL 1595 TT genotype was significantly lower in patients with bladder cancer compared to controls (p<0.001; odds ratios [OR]=0.143; 95% confidence interval [CI]=0.045-0.454). A significantly increased risk for developing bladder cancer was found for the group bearing a C allele for TRAIL C1595T polymorphism (p<0.001; OR=1.256; 95% CI=1.138-1.386). The observed genotype and allele frequencies of DR4 626 C/G in all groups were in agreement with the Hardy-Weinberg equilibrium (p=0.540). However, the frequency of DR4 GG genotype was found to be 2.1-fold increased in the bladder cancer patients with high-grade tumor, when compared to those having low-grade tumor (p=0.036). Additionally, combined genotype analysis showed that the frequency of TRAILCT-DR4GG was significantly higher in patients with bladder cancer in comparison with those of controls (p=0.037; OR=2.240; 95% CI=1.138-1.386).

CONCLUSIONS

Our study provides new evidence that TRAIL 1595 C allele may be used as a low-penetrant risk factor for bladder cancer development in a Turkish population. Otherwise, gene-gene interaction analysis revealed that the DR4GG genotype may have a predominant effect on the increased risk of bladder cancer over the TRAIL CT genotype.

Association of death receptor 4, Caspase 3 and 5 gene polymorphism with increased risk to bladder cancer in North Indians

PURPOSE

Perturbed apoptosis due to missense alterations in candidate tumor suppressor gene Death receptor 4 (DR4) and in caspases (Casp) lead to deregulated cell proliferation and cancer predisposition. Some data indicate that normal variations within the sequence of apoptotic genes may lead to suboptimal apoptotic capacity and therefore increased cancer risk. To test our proposal we examined whether six single nucleotide polymorphisms (SNPs) of the DR4 and Casp3, 5 genes contrive the risk of bladder cancer (BC) in a North Indian population.

MATERIALS AND METHODS

Genotyping was performed in 200 BC patients and 225 controls by Allele-specific PCR and by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

In DR4 Arg141His, BC patients having AA genotype (p = 0.036; OR = 2.51. In Casp5Leu13Phe G > C, significant association was observed with GC (p = 0.025; OR = 1.78) and also in GC + CC (p = 0.026; OR = 1.68). C allele carriers in Casp5Ala90Thr T > C showed low risk of BC (p = 0.036; OR = 0.83). While in Casp3 G > A, AG (p = 0.003; OR = 2.11), GG (p = 0.050; OR = 2.18), G allele (p < 0.001; OR = 1.85) and its carrier AG + GG (p = 0.001; OR = 2.12) have shown significant BC risk. Significant association between DR4 Ala228Glu polymorphism and smoking was observed in BC risk. Haplotype analysis demonstrated that DR4 (Thr209Arg-Arg141His-Ala228Glu) C-G-C is associated with 1.8 folds (OR = 1.85; p = 0.033) risk. GG genotype of Casp3 G > A polymorphism showed increased risk of recurrence (p = 0.009; HR = 5.20).

CONCLUSION

This study provided new support for the association of DR4 and Casp3, 5 in BC development, the tumorigenic effect of which was observed to be more enhanced in case of smoking exposure.

Association of death receptor 4 variant (683A > C) with ovarian cancer risk in BRCA1 mutation carriers

Dysregulation of apoptosis plays an important role in carcinogenesis. Therefore, apoptosis-associated genes like the death receptor 4 (DR4, TRAIL-R1) are interesting candidates for modifying the penetrance of breast and ovarian cancer in carriers of BRCA1 and BRCA2 mutations. The DR-4 haplotype 626C-683C [626C > G, Thr209Arg (rs4871857) and 683A > C, Glu228Ala (rs17088993)] has recently been linked to an increased risk of breast cancer. To evaluate whether DR4 626C > G or DR4 683A > C modifies the risk of breast or ovarian cancer in carriers of BRCA1 and BRCA2 mutations, we undertook a national multicenter study including data of 840 carriers of breast cancer gene (BRCA) mutations. DNA samples were collected from 12 German research centers between 1996 and 2005 and were genotyped by the Taqman allelic discrimination assay. The association between genotypes and incidence of breast or ovarian cancer data was evaluated using a Cox proportional hazards regression model. We found evidence for a significant association of DR4 683A > C with a higher risk for ovarian cancer in carriers of BRCA1 mutations [n = 557, hazard ratio 1.78 (1.24-2.55), p = 0.009]. Our results thus indicate that the DR4 683A > C variant modifies the risk of ovarian cancer in carriers of BRCA1 mutations.

Distinct TRAIL resistance mechanisms can be overcome by proteasome inhibition but not generally by synergizing agents

One impediment to the use of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor-targeted agents as antitumor drugs is the evolution of resistance, a common problem in cancer. On the contrary, many different kinds of drugs synergize with TRAIL in TRAIL-sensitive tumor cells, raising the question whether one can overcome resistance with the same drugs producing synergy. This is an important question, because recent clinical trials suggest that combination treatments with cytotoxic drugs and TRAIL receptor-targeted agents do not provide additional benefit compared with cytotoxic agents on their own. Such results might be expected if drug combinations that synergize in sensitive tumor cells but cannot overcome TRAIL resistance are used in patients whose tumors were not selected for retention of TRAIL sensitivity. We tested this idea by creating isogenic tumor cells with acquired TRAIL resistance or defined mechanisms of resistance that occur in human tumors and then comparing them to the TRAIL-sensitive parental cell line. Although diverse classes of anticancer drugs were all able to synergize with TRAIL in sensitive cells, most agents were unable to overcome resistance and there was no relationship between the amount of synergy seen with a particular agent and its ability to overcome acquired resistance. An important exception was proteasome inhibitors, which were, however, able to overcome diverse resistance mechanisms. Our findings suggest that one should select drugs for TRAIL receptor agonist combination therapy based not just on their ability to synergize, but rather on their ability to overcome resistance as well as synergize.

Local regulation of human breast xenograft models

Breast cancer studies implant human cancer cells under the renal capsule, subcutaneously, or orthotopically and often use estrogen supplementation and immune suppressants (etoposide) in xenograft mouse models. However, cell behavior is significantly impacted by signals from the local microenvironment. Therefore, we investigated how the combinatorial effect of the location of injection and procedural differences affected xenograft characteristics. Patient-derived breast cancer cells were injected into mouse abdominal or thoracic mammary glands +/- estrogen and/or etoposide pretreatment. Abdominal xenografts had increased tumor incidence and volume, and decreased latency (P < 0.001) compared to thoracic tumors. No statistically significant difference in tumor volume was found in abdominal xenografts treated +/- estrogen or etoposide; however, etoposide suppressed tumor volume in thoracic xenografts (P < 0.02). The combination of estrogen and etoposide significantly decreased tumor incidence in both sites. In addition, mice treated +/- estradiol were injected orthotopically or subcutaneously with well-characterized breast cancer cell lines (MCF7, ZR75-1, MDA MB-231, or MCF10Ca1h). Orthotopic injection increased tumor volume; growth varied with estrogen supplementation. Location also altered methylation status of several breast cancer-related gene promoters. Lastly, vascularization of orthotopic tumors was significantly enhanced compared to subcutaneous tumors. These data suggest that optimal xenograft success occurs with orthotopic abdominal injections and illustrate molecular details of the compelling influence of the local microenvironment on in vivo models.

Prognostic significance of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor expression in patients with breast cancer

TNF-related apoptosis-inducing ligand (TRAIL) induces apoptosis upon binding to TRAIL receptors 1 and 2 (TRAIL-R1/DR4 and TRAIL-R2/DR5). TRAIL-R3 (DcR1) and TRAIL-R4 (DcR2) have no or only a truncated cytoplasmic death domain. Consequently, they cannot induce apoptosis and instead have been proposed to inhibit apoptosis induction by TRAIL. Agonists for the apoptosis-inducing TRAIL-R1 and TRAIL-R2 are currently tested in clinical trials. To determine the expression pattern of all surface-bound TRAIL receptors and their prognostic clinical value, we investigated tumour samples of 311 patients with breast cancer by immunohistochemistry. TRAIL receptor expression profiles were correlated with clinico-pathological data, disease-free survival and overall survival. TRAIL-R1 was more strongly expressed in better differentiated tumours, and correlated positively with surrogate markers of a better prognosis (hormone receptor status, Bcl-2, negative nodal status), but negatively with the expression of Her2/neu and the proliferation marker Ki67. In contrast, TRAIL-R2 and TRAIL-R4 expression correlated with higher tumour grades, higher Ki67 index, higher Her2/neu expression and a positive nodal status at the time of diagnosis, but with lower expression of Bcl-2. Thus, the TRAIL receptor expression pattern was predictive of nodal status. Patients with grade 1 and 2 tumours, who had TRAIL-R2 but no TRAIL-R1, showed a positive lymph node status in 47% of the cases. Vice versa, only 19% had a positive nodal status with high TRAIL-R1 but low TRAIL-R2. Most strikingly, TRAIL-R4 and -R2 expression negatively correlated with overall survival of breast cancer patients. Although TRAIL-R2 correlated with more aggressive tumour behaviour, mammary carcinoma could be sensitised to TRAIL-R2-induced apoptosis, suggesting that TRAIL-R2 might therefore be used to therapeutically target such tumours. Hence, determination of the TRAIL receptor expression profile may aid in defining which breast cancer patients have a higher risk of lymph node metastasis and worse overall survival and on the other hand will help to guide TRAIL-based tumour therapy.

TRAIL-R1 polymorphisms and cancer susceptibility: an evidence-based meta-analysis

Published data on the association between tumour necrosis factor-related apoptosis-inducing ligand receptor 1 (TRAIL-R1 or DR4) polymorphisms rs20575 (C626G), rs2230229 (A1322G) and rs20576 (A683C) and cancer risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. A total of nine studies, among which eight articles including 2941 cases and 3358 controls described C626G genotypes, three articles including 736 cases and 668 controls described A1322G genotypes and three studies totalling 1550 cases and 2257 controls described A683C genotypes were involved in this meta-analysis. Overall, all three polymorphisms were associated with cancer susceptibility. For C626G polymorphism, there was no association between C626G polymorphism and the risk of cancer in all genetic models when all the eligible studies were pooled into the meta-analysis. In the subgroup analysis by source of controls, statistically significantly reduced cancer risks were found among groups with population-based controls for CG versus CC (OR=0.77, 95% CI:0.65-0.91, P(heterogeneity)=0.007) and dominant model (OR=0.84, 95% CI:0.72-0.99, P(heterogeneity)=0.409). For A1322G polymorphism, we found it was associated with a significantly elevated cancer risk of all cancer types in different genetic models (homozygote comparison: OR=2.80, 95% CI:1.16-6.76, P(heterogeneity)=0.905; dominant model comparison: OR=1.57, 95% CI:1.02-2.41, P(heterogeneity)=0.167; and recessive model comparison: OR=1.22, 95% CI:0.94-1.60, P(heterogeneity)=0.535). Similar results were obtained from A683C polymorphism (homozygote comparison: OR=3.21, 95% CI:1.26-8.20, P(heterogeneity)=0.012; dominant model comparison: OR=1.61, 95% CI: 1.09-2.36, P(heterogeneity)=0.000; and recessive model comparison: OR=2.79, 95% CI: 1.17-6.68, P(heterogeneity)=0.025). In summary, this meta-analysis suggests that TRAIL-R1 C626G polymorphism is marginally associated with cancer susceptibility, and both TRAIL-R1 A1322G G allele and A683C C allele are associated with increased risk for cancer.

The Potential of the Tumor Microenvironment to Influence Apo2L/TRAIL Induced Apoptosis

Apo2L/TRAIL ligation of specific cell surface receptors (DR4 and DR5) induces apoptosis of many malignant cells with little effect on normal cells. This anti-tumor capability has been demonstrated using cell lines of many tumor types, both in vitro and in vivo when the cells are grown as xenografts. We have extended these studies to investigate the efficacy of Apo2L/TRAIL against patient tumor xenografts in SCID mice and found that the growth of many tumors, both of primary and metastatic origin, can be inhibited by Apo2L/TRAIL. The basis of resistance to Apo2L/TRAIL induced apoptosis in malignant cells and normal cells is not completely understood, but it is known that a variety of factors including hypoxia, MMPs and cytokines present in the tumor microenvironment can influence the response of malignant cells to Apo2L/TRAIL. Currently, the clinical potential of several molecules targeting the Apo2L/TRAIL receptors DR4 and DR5 is being investigated. Our goal in this review is to provide a brief overview of a number of factors that have potential to influence the response of patient tumors to Apo2L/TRAIL.

Tumor resistance to apoptosis

One of the hallmarks of human cancers is the intrinsic or acquired resistance to apoptosis. Evasion of apoptosis may contribute to carcinogenesis, tumor progression and also to treatment resistance, since most current anticancer therapies including chemotherapy, radio- and immunotherapy primarily act by activating cell death pathways including apoptosis in cancer cells. Hence, a better understanding of the molecular mechanisms underlying tumor resistance to apoptotic cell death is expected to provide the basis for a rational approach to develop molecular targeted therapies.

The 'kiss of death' by dendritic cells to cancer cells

Dendritic cells (DCs) are professional antigen-presenting cells (APCs) specialized in the stimulation of naïve T lymphocytes, which are key components of antiviral and antitumor immunity. DCs are 'sentinels' of the immune system endowed with the mission to (1) sense invading pathogens as well as any form of tissue distress and (2) alert the effectors of the immune response. They represent a very heterogeneous population including subsets characterized by their anatomical locations and specific missions. Beyond their unique APC features, DCs exhibit a large array of effector functions that play critical roles in the induction and regulation of the cell-mediated as well as humoral immune responses. In the course of the antitumor immune response, DCs are unique in engulfing tumor cells killed by natural killer (NK) cells and cross-presenting tumor-associated antigens to cytotoxic T lymphocytes (CTLs). However, while DCs mediate antitumor immune responses by stimulating tumor-specific CTLs and NK cells, direct tumoricidal mechanisms have been recently evoked. This review addresses the other face of DCs to directly deliver apoptotic signals to stressed cells, their role in tumor cell death, and its implication in the design of DC-based cancer immunotherapies.

Death receptor 4 variants and colorectal cancer risk

The tumor necrosis factor-related apoptosis-inducing ligand receptor modulates apoptotic response by binding to the proapoptotic death receptor 4 (DR4). Perturbed apoptosis due to missense alterations in the candidate tumor suppressor gene DR4 leads to deregulated cell proliferation and cancer predisposition. Recent studies have discussed the association of DR4 variants with cancer risk. We evaluated, for the first time, the role of the Thr(209)Arg (626C>G) and Glu(228)Ala (683A>C) polymorphisms on colorectal cancer risk by genotyping 659 incident cases and 607 healthy controls drawn from the German population-based Darmkrebs: Chancen der Verhütung durch Screening (DACHS) study. Whereas DR4 Glu(228)Ala was not associated with colorectal cancer, Thr(209)Arg heterozygotes were at a significantly decreased colorectal cancer risk [odds ratio (OR), 0.73; 95% confidence interval (95% CI), 0.54-0.97]. Stratification according to sex and age exhibited a significant association of Thr(209)Arg with a decreased risk for male heterozygotes (OR, 0.68; 95% CI, 0.46-0.99) and for Arg(209) carriers > or =65 years of age (OR, 0.65; 95% CI, 0.46-0.92) as well as an enhanced risk for female Ala(228) carriers in a allele dose-dependent manner (P(trend) = 0.01). Subsite analysis revealed a protective effect of Thr(209)Arg for rectal cancer risk (OR, 0.67; 95% CI, 0.48-0.95) and a significant risk increase for Ala(228) carriers with advanced colorectal cancer stages (P(trend) = 0.04). Haplotype analysis revealed a 2.4-fold risk for carriers of the rare 626C-683C haplotype (1% prevalence in the general population; OR, 2.37; 95% CI, 0.98-5.76). The score statistic yielded an empirical P of 0.03 of the haplotype-specific test for 626C-683C based on 20,000 simulations, suggesting that DR4 626C-683C may affect colorectal cancer predisposition.

TRAIL death receptor-4 expression positively correlates with the tumor grade in breast cancer patients with invasive ductal carcinoma

PURPOSE

Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) selectively induces apoptosis in cancer cells but not in normal cells, and a number of clinical trials have recently been initiated to test the safety and antitumoral potential of TRAIL in cancer patients. Four different receptors have been identified to interact with TRAIL: two are death-inducing receptors (TRAIL-R1 [DR4] and TRAIL-R2 [DR5]), whereas the other two (TRAIL-R3 [DcR1] and TRAIL-R4 [DcR2]) do not induce death upon ligation and are believed to counteract TRAIL-induced cytotoxicity. Because high levels of DcR2 expression have recently been correlated with carcinogenesis in the prostate and lung, this study investigated the importance of TRAIL and TRAIL receptor expression in breast cancer patients with invasive ductal carcinoma, taking various prognostic markers into consideration.

METHODS AND MATERIALS

Immunohistochemical analyses were performed on 90 breast cancer patients with invasive ductal carcinoma using TRAIL and TRAIL receptor-specific antibodies. Age, menopausal status, tumor size, lymph node status, tumor grade, lymphovascular invasion, perineural invasion, extracapsular tumor extension, presence of an extensive intraductal component, multicentricity, estrogen and progesterone receptor status, and CerbB2 expression levels were analyzed with respect to TRAIL/TRAIL receptor expression patterns.

RESULTS

The highest TRAIL receptor expressed in patients with invasive ductal carcinoma was DR4. Although progesterone receptor-positive patients exhibited lower DR5 expression, CerbB2-positive tissues displayed higher levels of both DR5 and TRAIL expressions.

CONCLUSIONS

DR4 expression positively correlates with the tumor grade in breast cancer patients with invasive ductal carcinoma.

Multiple mechanisms underlie resistance of leukemia cells to Apo2 Ligand/TRAIL

Targeting death receptors with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has the remarkable potential to selectively kill malignant cells whereas normal cells are largely unaffected by this treatment. However, some tumor cells, including leukemia cells, exhibit resistance to this molecule. To investigate the basis for resistance of leukemia cells to the zinc-bound form of Apo2 ligand (Apo2L)/TRAIL, which is currently being evaluated in clinical trial, we isolated several resistant HL60 clones from parental HL60 cells by selection using the recombinant Apo2L/TRAIL. Differing resistance mechanisms were identified and characterized in these Apo2L/TRAIL-resistant clones. In one case, the level of the cell-surface death receptor DR4, but not DR5, was significantly decreased. However, these cells did undergo apoptosis in response to another form of recombinant TRAIL, histidine-tagged TRAIL, suggesting differing contributions of DR4 and DR5 in the response to these two forms of TRAIL. In the case of other clones, expression of procaspase-8 protein was lost and this was associated with a novel Leu(22)-->Phe(22) point mutation in CASP-8 gene. These results show that cells within a given tumor can have widely distinct mechanisms underlying resistance to Apo2L/TRAIL.

Ala228 variant of trail receptor 1 affecting the ligand binding site is associated with chronic lymphocytic leukemia, mantle cell lymphoma, prostate cancer, head and neck squamous cell carcinoma and bladder cancer

Allelic loss of chromosome 8p21-22 is a frequent event in various human cancers including mantle cell lymphoma (MCL), prostate cancer, head and neck squamous cell carcinoma (HNSCC) and bladder cancer. The tumor necrosis factor-related apoptosis inducing ligand (TRAIL) receptors, including TNFRSF10A and TNFRSF10B, are located within this chromosomal region. Since recent studies demonstrate that chronic lymphocytic leukemia (CLL) and prostate cells are TRAIL induced apoptosis, TRAIL-receptors are strong tumor suppressor candidate genes in human cancers exhibiting loss of chromosomal material in 8p21.3. However, no mutation of the TRAIL receptor genes has been reported in CLL, MCL, prostate cancer, HNSCC so far. In this study we analyzed the complete coding region of TNFRSF10A and TNFRSF10B in a series of 32 MCL and 101 CLL samples and detected a single nucleotide polymorphism (SNP) in TNFRSF10A (A683C) with tumor specific allele distribution. We examined allele distribution in 395 samples of different tumor entities (prostate cancer, n = 43; HNSCC, n = 40; bladder cancer, n = 179) and compared them to 137 samples from healthy probands. We found the rare allele of TNFRSF10A is more frequent in CLL, MCL, prostate cancer, bladder cancer and HNSCC. The A683C polymorphism did not cosegregate with other TNFRSF10A polymorphisms previously described. Thus screening for 683A-->C nucleotide exchanges may become important in diagnosis and/or treatment of these malignancies.

Association of death receptor 4 haplotype 626C-683C with an increased breast cancer risk

Dysregulation of apoptosis plays a crucial role in carcinogenesis. Tumour necrosis factor-related apoptosis-inducing ligand stimulates the extrinsic apoptotic pathway by binding to death receptor 4 (DR4). Thus, genetic alterations within the candidate tumour suppressor gene DR4 would be expected to provoke a deficient apoptotic signalling thereby facilitating the development of cancer. The DR4 variants Thr209Arg and Glu228Ala were genotyped in a series of 521 breast cancer cases and 1100 control subjects from Germany, determining their impact on breast cancer risk. Neither Thr209Arg (626C>G) nor Glu228Ala (683A>C) alone were significantly associated with breast cancer risk [odds ratio (OR) = 0.84, 95% confidence interval (CI) = 0.65-1.08, P = 0.18 and OR = 0.89, 95% CI = 0.72-1.12, P = 0.30]. However, haplotype analysis revealed a 3.5-fold risk for carriers of the 626C-683C haplotype (OR = 3.52, 95% CI = 1.45-8.52, P = 0.003).

Absence of gene mutation in TRAIL receptor 1 (TRAIL-R1) and TRAIL receptor 2 (TRAIL-R2) in chronic myelogenous leukemia and myelodysplastic syndrome, and analysis of mRNA Expressions of TRAIL and TRAIL-related genes in chronic myelogenous leukemia

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is an interferon (IFN)-induced molecule with apoptotic activity. We examined gene mutations in the death domains of TRAIL receptor 1 (TRAIL-R1) and TRAIL receptor 2 (TRAIL-R2), and in the TRAIL gene promoter in 46 chronic myelogenous leukemia (CML) patients. In 23 of the 46 patients, all the coding regions of TRAIL-R2 were also examined. However, no mutation or loss of heterozygosity was found. Furthermore, no mutation in the death domains of TRAIL-R1 and TRAIL-R2 genes, which causes amino acid change, was found in 18 myelodysplastic syndrome (MDS) patients. Ribonuclease protection assay (RPA) and real-time quantitative polymerase chain reaction using polymorphonuclear neutrophils of five new CML patients showed that the TRAIL mRNA expression was very low before in vitro IFN-alpha stimulation and markedly upregulated after IFN-alpha stimulation. FAS mRNA was also upregulated with IFN-alpha stimulation but the fold induction was far lower than that of TRAIL mRNA. In addition, RPA revealed that the ratio of (TRAIL-R1 plus TRAIL-R2) to TRAIL-R3 was also increased after IFN-alpha stimulation. Taken together, gene mutations of TRAIL-R1, TRAIL-R2 are infrequent in patients with CML and MDS. And so is the TRAIL promoter for CML. These mutations seem unrelated to tumorigenesis, disease progression, and response to IFN-alpha therapy in CML. A markedly high induction of TRAIL mRNA by IFN-alpha may have some relevance to IFN-alpha action in CML patients.

Death receptor 4 (DR4) efficiently kills breast cancer cells irrespective of their sensitivity to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)

Breast cancer cells are generally resistant to induction of apoptosis by treatment with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). In this study, we demonstrate that both TRAIL-sensitive and TRAIL-resistant breast cancer cell lines can be efficiently killed by overexpression of the TRAIL receptor, death receptor 4 (DR4). The extent of cell death depended on the strength of the promoter driving DR4 expression. When driven by the strong CMV promoter, expression of DR4 killed over 90% of cells in five out of six cell lines tested in the absence of exogenous TRAIL. When driven by the relatively weak tumor-specific hTERT promoter, DR4 was less effective alone, but sensitized cells to killing by TRAIL. The extent of TRAIL sensitization depended on the magnitude of hTERT promoter activity. MCF-7 cells were relatively resistant to the action of DR4. We compared expression of the genes involved in transduction and execution of the death receptor-initiated apoptotic stimuli between MCF-7 and DR4-sensitive cell lines. We confirmed that in the panel of cell lines, MCF-7 was the only line deficient in expression of caspase 3. Bcl-2 and FLIP proteins, implicated in suppression of TRAIL-induced apoptosis, were expressed at a higher level.

Interferon-Gamma and TRAIL in Human Breast Tumor Cells

Induction of apoptosis in tumor cells by death receptor activation is a novel therapeutic strategy. However, in systemic antitumor treatments, severe toxic effects have been observed with tumor necrosis factor-alpha (TNF-alpha) and CD95 ligand. TNF-alpha causes a lethal inflammatory response and CD95L produces lethal liver damage. Preclinical studies in mice and nonhuman primates showed no systemic cytotoxicity upon injection of recombinant TNF-related apoptosis-inducing ligand (TRAIL) at doses that effectively suppressed solid tumors such as colon and mammary carcinomas. Although unwanted effects of some TRAIL preparations have been reported in normal cells, these data suggest that TRAIL could be a suitable approach in cancer therapy. However, several mechanisms of resistance to TRAIL-mediated apoptosis have been described in tumor cells such as lack of TRAIL apoptotic receptors, enhanced expression of TRAIL-decoy receptors, and expression of apoptosis inhibitors. In combination regimes, interferon-gamma (IFN-gamma) could provide a promising antitumor therapeutic approach as it has been described to enhance cellular susceptibility to apoptosis in a variety of tumor cells. The mechanism by which IFN-gamma promotes cell death seems to be via the regulation of the expression of different proteins involved in apoptosis. Altogether, these data suggest a combination strategy to selectively kill tumor cells that need to be further explored.

Breast cancer in young women (?35 years): Genomic aberrations detected by comparative genomic hybridization

Sporadic breast cancer in young women is different from the one in older patients regarding pathological features and aggressiveness of the tumors, but the spectrum of genetic alterations are largely unknown. We used comparative genomic hybridization (CGH) to analyze DNA copy number changes in 88 tumor samples from women </=35 years of age. Findings were compared to histopathological data including tumor type, grading, lymph nodes and metastasis. Genomic gains clustered to chromosome arms 1q (64.8%), 8q (61.4%), 17q (50.0%), 20q (33.0%), 3q (20.5%), 1p (17.0%), 5p (17.0%) and 15q (17%). Losses were commonly located on 8p (19.3 %), 11q (11.4%), 16q (11.4%), 17p (11.4%) and 18q (10.2%). A comparison with published CGH data from breast carcinomas of similar type and grade showed the following differences: (1) gains were much more frequent than losses, and (2) losses on 8p22-p23 were more prevalent in patients with positive lymph node metastasis (p = 0.02), and Grade III tumors were associated with gains on the long arm of chromosome 8 (p = 0.01). Therefore, alterations in these genomic regions may be responsible for the reduced survival of patients with early onset breast cancer.

Analysis of DLC-1 expression in human breast cancer

The chromosome region 8p12-p22 shows frequent allelic loss in many neoplasms, including breast cancer (BC). The DLC-1 gene, located on 8p21-p22, might be a candidate tumor suppressor gene in this region. To evaluate the involvement of DLC-1 in breast carcinogenesis we studied DLC-1 mRNA expression in a panel of 14 primary human BC and the corresponding normal breast cells as well as 8 BC cell lines. Low levels or absence of DLC-1 mRNA were observed in 57% of primary BC and 62.5% of BC cell lines, respectively. We could not find any correlation between DLC-1 mRNA expression and deletions at the DLC-1 locus. Transfection of the gene into DLC-1 deficient T-47D cells raised the DLC-1 mRNA level and resulted in inhibition of cell growth and reduced colony-forming capacity. Our results indicate a role of DLC-1 in BC carcinogenesis.