The Fas/Fas-ligand system: a mechanism for immune evasion in human breast carcinomas

Estrogen receptor regulation of the immune microenvironment in breast cancer

Breast cancer (BCa) is the most common cancer in women and the estrogen receptor (ER)+ subtype is increasing in incidence. There are numerous therapy options available for patients that target the ER, however issues such as innate and acquired treatment resistance, and treatment related side effects justify research into alternative therapeutic options for these patients. Patients of many solid tumour types have benefitted from immunotherapy, however response rates have been generally low in ER+ BCa. We summarise the recent work assessing CDK4/6 inhibitors for ER+ BCa and how they have been shown to prime anti-tumour immune cells and achieve impressive results in preclinical models. A great example of how the immune system might be activated against ER+ BCa. We review the role of estrogen signalling in immune cells, and explore recent data highlighting the hormonal regulation of the immune microenvironment of normal breast, BCa and immune disorders. As recent data has indicated that macrophages are particularly susceptible to estrogen signalling, we highlight macrophage phagocytosis as a key potential target for priming the tumour immune microenvironment. We challenge the generally accepted paradigm that ER+ BCa are "immune-cold" - advocating instead for research into therapies that could be used in combination with targeted therapies and/or immune checkpoint blockade to achieve durable antitumour responses in ER+ BCa.

Hormone Receptor Signaling and Breast Cancer Resistance to Anti-Tumor Immunity

Breast cancers regroup many heterogeneous diseases unevenly responding to currently available therapies. Approximately 70-80% of breast cancers express hormone (estrogen or progesterone) receptors. Patients with these hormone-dependent breast malignancies benefit from therapies targeting endocrine pathways. Nevertheless, metastatic disease remains a major challenge despite available treatments, and relapses frequently ensue. By improving patient survival and quality of life, cancer immunotherapies have sparked considerable enthusiasm and hope in the last decade but have led to only limited success in breast cancers. In addition, only patients with hormone-independent breast cancers seem to benefit from these immune-based approaches. The present review examines and discusses the current literature related to the role of hormone receptor signaling (specifically, an estrogen receptor) and the impact of its modulation on the sensitivity of breast cancer cells to the effector mechanisms of anti-tumor immune responses and on the capability of breast cancers to escape from protective anti-cancer immunity. Future research prospects related to the possibility of promoting the efficacy of immune-based interventions using hormone therapy agents are considered.

Cholest-4,6-Dien-3-One Promote Epithelial-To-Mesenchymal Transition (EMT) in Biliary Tree Stem/Progenitor Cell Cultures In Vitro

Human biliary tree stem/progenitor cells (hBTSCs), reside in peribiliary glands, are mainly stimulated by primary sclerosing cholangitis (PSC) and cholangiocarcinoma. In these pathologies, hBTSCs displayed epithelial-to-mesenchymal transition (EMT), senescence characteristics, and impaired differentiation. Here, we investigated the effects of cholest-4,6-dien-3-one, an oxysterol involved in cholangiopathies, on hBTSCs biology. hBTSCs were isolated from donor organs, cultured in self-renewal control conditions, differentiated in mature cholangiocytes by specifically tailored medium, or exposed for 10 days to concentration of cholest-4,6-dien-3-one (0.14 mM). Viability, proliferation, senescence, EMT genes expression, telomerase activity, interleukin 6 (IL6) secretion, differentiation capacity, and HDAC6 gene expression were analyzed. Although the effect of cholest-4,6-dien-3-one was not detected on hBTSCs viability, we found a significant increase in cell proliferation, senescence, and IL6 secretion. Interestingly, cholest-4.6-dien-3-one impaired differentiation in mature cholangiocytes and, simultaneously, induced the EMT markers, significantly reduced the telomerase activity, and induced HDAC6 gene expression. Moreover, cholest-4,6-dien-3-one enhanced bone morphogenic protein 4 (Bmp-4) and sonic hedgehog (Shh) pathways in hBTSCs. The same pathways activated by human recombinant proteins induced the expression of EMT markers in hBTSCs. In conclusion, we demonstrated that chronic exposition of cholest-4,6-dien-3-one induced cell proliferation, EMT markers, and senescence in hBTSC, and also impaired the differentiation in mature cholangiocytes.

The Role of Immune Escape and Immune Cell Infiltration in Breast Cancer

While detailed analysis of aberrant cancer cell signaling pathways and changes in cancer cell DNA has dominated the field of breast cancer biology for years, there now exists increasing evidence that the tumor microenvironment (TME) including tumor-infiltrating immune cells support the growth and development of breast cancer and further facilitate invasion and metastasis formation as well as sensitivity to drug therapy. Furthermore, breast cancer cells have developed different strategies to escape surveillance from the adaptive and innate immune system. These include loss of expression of immunostimulatory molecules, gain of expression of immunoinhibitory molecules such as PD-L1 and HLA-G, and altered expression of components involved in apoptosis. Furthermore, the composition of the TME plays a key role in breast cancer development and treatment response. In this review we will focus on i) the different immune evasion mechanisms used by breast cancer cells, ii) the role of immune cell infiltration in this disease, and (iii) implication for breast cancer-based immunotherapies.

Clinicopathological and prognostic significance of programmed death ligand-1 expression in breast cancer: a meta-analysis

Background

Programmed cell death-ligand 1 (PD-L1) may be a useful molecule for targeted immunotherapy. Therefore, this meta-analysis aimed to investigate PD-L1 expression in breast cancer and its associations with clinicopathological factors and outcomes, which may help determine whether PD-L1 expression is a useful prognostic marker.

Methods

The Medline Ovid, Cochrane, PubMed, Google Scholar, and Web of Knowledge databases were searched for studies that evaluated the prognostic or clinicopathological significance of PD-L1 expression in patients with breast cancer, and reported at least one survival-related outcome.

Results

Six studies that included 7877 cases were selected for the analysis. Higher PD-L1 expression in all cells was related to higher histological grade and lymph node metastasis. Higher PD-L1 expression in tumor cell was related to larger tumor size, estrogen receptor negativity, progesterone receptor negativity, human epidermal growth factor type-2 positivity, and triple-negative breast cancer. PD-L1 positivity in all cells was associated with poorer disease-free survival, although it was not significantly associated with overall survival.

Conclusion

The present meta-analysis revealed that cases of breast cancer with PD-L1 positivity in all cells exhibited higher histological grades, lymph node metastasis, and poorer disease-free survival. Therefore, positive expression of PD-L1 may be a useful prognostic marker in breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3670-1) contains supplementary material, which is available to authorized users.

Circulating and disseminated tumour cells - mechanisms of immune surveillance and escape

Metastatic spread of tumour cells is the main cause of cancer-related deaths. Understanding the mechanisms of tumour-cell dissemination has, therefore, become an important focus for cancer research. In patients with cancer, disseminated cancer cells are often detectable in the peripheral blood as circulating tumour cells (CTCs) and in the bone marrow or lymph nodes as disseminated tumour cells (DTCs). The identification and characterization of CTCs and DTCs has yielded important insights into the mechanisms of metastasis, resulting in a better understanding of the molecular alterations and profiles underlying drug resistance. Given the expanding role of immunotherapies in the treatment of cancer, interactions between tumour cells and immune cells are the subject of intense research. Theoretically, cancer cells that exit the primary tumour site - leaving the protection of the typically immunosuppressive tumour microenvironment - will be more vulnerable to attack by immune effector cells; thus, the survival of tumour cells after dissemination might be the 'Achilles' heel' of metastatic progression. In this Review, we discuss findings relating to the interactions of CTCs and DTCs with the immune system, in the context of cancer immuno-editing, evasion from immune surveillance, and formation of metastases.

Prognostic relevance of caspase 8 -652 6N InsDel and Asp302His polymorphisms for breast cancer

Background

The minor allele of two caspase 8 polymorphisms, namely CASP8 -652 6N InsDel (rs3834129) and CASP8 Asp302His (rs1045485), were repeatedly associated with reduced breast cancer susceptibility. Contrarily, the presence of the -652 6N Del or the CASP8 302His variant was reported to be an unfavorable prognostic factor in colorectal cancer or neuroblastoma. However, prognostic relevance of these genetic variants for breast cancer is completely unknown and is therefore adressed by the current study.

Methods

Genotyping was performed by pyrosequencing. Caspase 8 mRNA expression was quantified by comparative RT-qPCR.

Results

We observed an allele-dose dependent association between CASP8 -652 6N InsDel and caspase 8 mRNA expression in breast cancer tissue, with homozygous deletion carriers showing lowest relative caspase 8 expression (p = 0.0131). Intriguingly, the presence of the -652 6N Del or the 302His variant was shown to be a negative prognostic factor for breast cancer in terms of an allele-dose dependent influence on overall survival (OS, p = 0.0018, p = 0.0150, respectively). Moreover, both polymorphisms were independent predictors of OS after adjusting for co-variats (p = 0.007, p = 0.037, respectively). Prognostic relevance of both polymorphisms were confirmed to be independent from each other and combined analysis of diplotypes revealed an additive influence upon OS (p = 0.0002).

Conclusion

This is the first report, showing negative and independent prognostic impact of the CASP8 -652 6N Del and the 302His variant for breast cancer. Our data provide rationale to further validate clinical utility of these polymorphisms for breast cancer and to extend this investigation to a broad scope of other malignancies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2662-x) contains supplementary material, which is available to authorized users.

The association between the SNP rs763110 and the risk of gynecological cancer: a meta-analysis

FAS and FAS ligand (FASL) are the principal genes of the apoptosis pathway, which play a vital role in the etiology of various gynecological cancers. Studies have revealed that polymorphism of FASL promoter -844C>T (rs763110) influences FASL transcription process, which involving in cancer risk. Moreover, estrogen has been proved to trigger T-cell apoptosis by up-regulating FAS/FASL system in cancer cells. However, results from the published studies on the association between FASL -844C>T polymorphism and risk of gynecological cancer are conflicting. We performed a meta-analysis based on 13 case-control studies, including a total of 6256 cancer cases and 5573 controls. We used odd ratios (ORs) with 95% confidence intervals (CIs) to assess the association strength. Overall, the FASL -844CT and TT genotypes were associated with a significantly reduced risk of gynecological cancer types in homozygote comparison (OR=0.80, 95% CI=0.64-0.99), heterozygote comparison (OR=0.81, 95% CI=0.67-0.98), and dominant model (OR=0.81, 95% CI=0.67-0.98). In the stratified analyses, we observed a similar association among Asian population (heterozygote comparison: OR=0.73, 95% CI=0.56-0.95; dominant model: OR=0.75, 95% CI=0.57-0.98) and hospital-based studies (homozygote comparison: OR=0.61, 95% CI=0.43-0.86). When stratified by cancer type, there was also a significantly lower risk of the ovarian cancer in different genetic models except the recessive one. The results suggested that the FASL -844C>T polymorphism may reduce the risk of gynecological cancer.

The role of CD95 and CD95 ligand in cancer

CD95 (Fas/APO-1) and its ligand, CD95L, have long been viewed as a death receptor/death ligand system that mediates apoptosis induction to maintain immune homeostasis. In addition, these molecules are important in the immune elimination of virus-infected cells and cancer cells. CD95L was, therefore, considered to be useful for cancer therapy. However, major side effects have precluded its systemic use. During the last 10 years, it has been recognized that CD95 and CD95L have multiple cancer-relevant nonapoptotic and tumor-promoting activities. CD95 and CD95L were discovered to be critical survival factors for cancer cells, and were found to protect and promote cancer stem cells. We now discuss five different ways in which inhibiting or eliminating CD95L, rather than augmenting, may be beneficial for cancer therapy alone or in combination with standard chemotherapy or immune therapy.

Tumor cell lysate induces the immunosuppression and apoptosis of mouse immunocytes

Although tumor cell lysate (TCL) is a type of immunocyte stimulator, its immunosuppressive function must not be ignored. The present study reported that TCL prepared from a Lewis lung cancer cell was able to induce the development of immunosuppressive macrophages (MΦ) and tolerogenic dendritic cells. In addition, TCL upregulated the expression of CD69 in mouse splenocytes, and cell apoptosis and the percentage of regulatory T cells in mouse splenocytes simultaneously increased. Furthermore, the present study found that the immunosuppressive factor, hyaluronan, and the apoptosis inducers, Fas ligand and transforming growth factor-β, are present in TCL. These components may be associated with the emergence of immunosuppressive cells or splenocyte apoptosis. Thus, the present study has enriched our understanding of the composition of TCL and its negative regulatory effect on immunocytes.

Association between CD95L polymorphism and cervical cancer risk: evidence from a meta-analysis

Several studies have assessed the association of CD95L polymorphism with cervical cancer risk, but the data lack the power to provide compelling evidence. In this study, we aimed to clarify the association through a meta-analysis. A comprehensive search was conducted in PubMed, Embase, and Web of Science. The fixed-effects model was used to calculate odds ratio (OR) with 95 % confidence intervals (CIs). A total of five papers with six case-control studies were derived and finally included in this meta-analysis. The overall estimate did not reveal any significant association between CD95L -844C/T polymorphism and cervical cancer risk. Subgroup analysis in Asian population indicated nonsignificant nevertheless potentially increased risk in CC genotype carriers in comparison with the carriers of CT+TT genotypes (ORCC vs. CT+TT=1.16, 95 % CI=0.99-1.36, P for heterogeneity=0.231). Based on current epidemiological studies, this meta-analysis suggests that CD95L polymorphism may not be a risk factor contributing to cervical cancer development.

The immune system and inflammation in breast cancer

During different stages of tumor development the immune system can either identify and destroy tumors, or promote their growth. Therapies targeting the immune system have emerged as a promising treatment modality for breast cancer, and immunotherapeutic strategies are being examined in preclinical and clinical models. However, our understanding of the complex interplay between cells of the immune system and breast cancer cells is incomplete. In this article, we review recent findings showing how the immune system plays dual host-protective and tumor-promoting roles in breast cancer initiation and progression. We then discuss estrogen receptor α (ERα)-dependent and ERα-independent mechanisms that shield breast cancers from immunosurveillance and enable breast cancer cells to evade immune cell induced apoptosis and produce an immunosuppressive tumor microenvironment. Finally, we discuss protumorigenic inflammation that is induced during tumor progression and therapy, and how inflammation promotes more aggressive phenotypes in ERα positive breast cancers.

Quantitative assessment of the association between three polymorphisms in FAS and FASL gene and breast cancer risk

FAS and FAS ligand (FASL) play crucial roles in apoptotic signaling, and deregulation of this pathway may facilitate carcinogenesis. Studies on the association between the FAS/FASL polymorphisms (FAS-1377G/A rs2234767, FAS-670A/G rs1800682, and FASL-844C/T rs763110) and breast cancer risk have reported inconsistent results. Therefore, to characterize the relationship between those polymorphisms and breast cancer risk, we undertook a meta-analysis of those studies. Several electronic databases were searched for articles on the FAS/FASL polymorphisms and breast cancer risk. The genotype data were extracted; pooled odds ratios (OR) with 95% confidence intervals (CIs) were used to estimate the strength of the association. Five studies were eligible for our meta-analysis. Overall, we observed significant associations of the FAS-1377G/A polymorphism with breast cancer susceptibility (AG vs. GG: OR = 1.15, 95% CI 1.02-1.30; AA vs. GG: OR = 1.39, 95% CI 1.12-1.72; AG/AA vs. GG: OR = 1.18, 95% CI, 1.16-1.32; A vs. G: OR = 1.16, 95% CI 1.06-1.26), but we did not observe significant association of the Fas-670A/G and FasL-844C/T polymorphisms with breast cancer risk. In the subgroup analysis, we observed that the FAS-1377G/A and FASL-844C/T polymorphisms were associated with breast cancer risk in Chinese but not Whites; we still did not observed association of the FAS-670A/G polymorphism with breast cancer risk. Our meta-analysis revealed that FAS-1377G>A polymorphism was associated with an increased risk of breast cancer. FASL-844C>T polymorphism might be associated with a reduced breast cancer risk in Chinese. However, FAS-670A/G had no any effect on breast carcinogenesis.

Functional polymorphisms of FAS and FASL gene and risk of breast cancer - pilot study of 134 cases

Fas/Fas ligand (FasL) system is one of the key apoptotic signaling entities in the extrinsic apoptotic pathway. De-regulation of this pathway, i.e. by mutations may prevent the immune system from the removal of newly-formed tumor cells, and thus lead to tumor formation. The present study investigated the association between −1377 G/A (rs2234767) and −670 A/G (rs1800682) polymorphisms in Fas as well as single nucleotide polymorphisms INV2nt −124 A/G (rs5030772) and −844 C/T (rs763110) in FasL in a sample of Iranian patients with breast cancer. This case-control study was done on 134 breast cancer patients and 152 normal women. Genomic DNA was extracted from whole blood samples. The polymorphisms were determined by using tetra-ARMS-PCR method. There was no significant difference in the genotype distribution of FAS rs2234767 polymorphism between cases and controls. FAS rs1800682, FASL rs5030772, and FASL rs763110 genotypes showed significant associations with an increasing risk of breast cancer (odds ratio OR = 3.18, P = 0.019; OR = 5.08, P = 0.012; OR = 2.40, P = 0.024, respectively). In conclusion, FAS rs2234767 was not associated with breast cancer risk. Though, FAS rs1800682, FASL rs5030772, and FASL rs763110 polymorphisms were associated with the risk of breast cancer in the examined population.

Weapons ovarian epithelial tumors may use in immune escape: an immunohistochemical correlational study

Investigate FasL and survivin expression in a series of primary ovarian surface epithelial tumors, correlate their expression with each other, and characterize the presence of CD3+ T-lymphocytes in studied tumors and determine whether their presence correlates with FasL or survivin expression in malignant cases. FasL and survivin expression was assessed in 54 ovarian epithelial tumors. The results were compared between different tumor types and grades. Correlation between both markers' expression in all studied tumors was done. Either marker's expression was compared to the mean CD3+ T-lymphocytes per HPF in the studied malignant tumors. Either FasL or survivin expression was significantly higher in malignant versus benign ovarian epithelial tumors (p < 0.001 for both) and both markers were strongly correlated to each other (r = 0.877 & p < 0.001). Malignant tumors show significantly higher mean CD3+ T-lymphocytes than benign and borderline tumors. The mean CD3+ T-lymphocytes decrease significantly on increasing malignant tumor grade (p = 0.019) and expression of both FasL and survivin (r = -0.729, -0.582, respectively & p < 0.001 for both). The higher expression of FasL and survivin in malignant as compared to benign ovarian tumors suggest that they have a significant role in pathogenesis of ovarian carcinoma. Both markers are strongly correlated to each other and may contribute to immune escape of ovarian carcinoma as their higher expression is associated with decreased number of CD3 + T-lymphocytes.

Immuno-modulatory gene polymorphisms and outcome in breast and ovarian cancer

Breast and ovarian cancer continue to be a significant source of morbidity and mortality. Improved understanding of signalling pathways related to growth and apoptosis has led to targeted treatments and modest improvement in long term outcomes. However, it has become increasingly clear that tumor factors alone are not the sole determinants of outcome in patients with breast and ovarian cancer. The tumor microenvironment and other immunologic host processes play an integral role in the overall interactions between disease, host and treatment. Cytokines play a major role in the immune response to tumors. Single nucleotide polymorphisms (SNPs) in the regulatory or coding regions of many cytokine genes lead to functional alterations in the transcriptional regulation of these genes or the proteins they encode. This review examines the current literature linking functional variants in cytokine and other immune genes to outcomes in breast and ovarian cancer. We have focused on those involved in the proinflammatory response (IL-6, TNF-alpha), apoptosis (TGF-beta, Fas, FasL, C1QA), angiogenesis (IL-8) and autoimmunity (IL-10). While much remains to be learned about the mechanisms underlying these variants and their impact on tumor behavior, this area holds promise for future development of prognostic profiles and therapeutics exploiting the immune response.

Sphingolipids as determinants of apoptosis and chemoresistance in the MCF-7 cell model system

An estimated 182,640 women and 1,990 men were diagnosed with breast cancer in 2008, and approximately 40,480 women and 450 men died from the disease. Thus, continued mechanistic studies are needed to understand the causes and develop additional therapeutics for this complicated disease. The MCF-7 cell system is one of the most recognized models for estrogen receptor (ER)-positive breast cancer and has generated approximately 13,000 publications cited in PubMed to date. A number of clues for biological mechanisms related to apoptotic/anti-apoptotic pathways and chemoresistance were elucidated and summarized in our previous review. The focus of this review is new knowledge of the central role of sphingolipid signaling in apoptotic mechanisms in estrogen receptor-positive breast cancer. The ultimate goal is to target crucial steps in survival signaling pathways that may ultimately provide additional translational solutions to the successful pharmacologic treatment of breast cancer.

Expression of B7-H1 in breast cancer patients is strongly associated with high proliferative Ki-67-expressing tumor cells

B7-H1, a co-inhibitory molecule, plays a role in immune escape of tumors. We have shown previously the expression of this molecule in breast cancer patients and demonstrated its association with high histological grade, progesterone and estrogen receptor negative status, all of which are known to have direct impact on cell proliferation. In the present work, we investigated the effect of proliferation, as measured by Ki-67 and mitotic count, on the induction of B7-H1. We used H&E stained sections to score for mitotic count in 69 breast cancer patients. Immunohistochemistry was used to investigate B7-H1 and Ki-67 expression. The relationship between B7-H1 induction and cell proliferation was further investigated in primary cultured cells. B7-H1 expression was recorded in patients with a high mitotic index (p = 0.007). There was a high significant correlation between B7-H1 expression and the presence of the proliferative marker Ki-67 (p < 0.001) indicating the association of proliferation with B7-H1 induction. Furthermore, B7-H1 was gradually induced in proliferating cells of 8/8 primary cell lines as measured by Ki-67 expression. Finally, B7-H1 was downregulated in quiescent cells and upregulated in cells stimulated with a mitogen confirming the association of proliferation with the induction of B7-H1. We have shown for the first time a direct association between proliferation and the expression of B7-H1 in breast cancer patients. The relationship between B7-H1 induction and cell proliferation was also thoroughly investigated in vitro, in which a strong link between B7-H1 expression and the presence of the proliferative Ki-67 marker was clearly demonstrated.

A six-nucleotide insertion-deletion polymorphism in the CASP8 promoter is associated with susceptibility to multiple cancers

Caspases are important in the life and death of immune cells and therefore influence immune surveillance of malignancies. We tested whether genetic variants in CASP8, CASP10 and CFLAR, three genes important for death receptor-induced cell killing residing in tandem order on chromosome 2q33, are associated with cancer susceptibility. Using a haplotype-tagging SNP approach, we identified a six-nucleotide deletion (-652 6N del) variant in the CASP8 promoter associated with decreased risk of lung cancer. The deletion destroys a stimulatory protein 1 binding site and decreases CASP8 transcription. Biochemical analyses showed that T lymphocytes with the deletion variant had lower caspase-8 activity and activation-induced cell death upon stimulation with cancer cell antigens. Case-control analyses of 4,995 individuals with cancer and 4,972 controls in a Chinese population showed that this genetic variant is associated with reduced susceptibility to multiple cancers, including lung, esophageal, gastric, colorectal, cervical and breast cancers, acting in an allele dose-dependent manner. These results support the hypothesis that genetic variants influencing immune status modify cancer susceptibility.

The B7-H1 (PD-L1) T lymphocyte-inhibitory molecule is expressed in breast cancer patients with infiltrating ductal carcinoma: correlation with important high-risk prognostic factors

B7-H1 molecule increases the apoptosis of tumor-reactive T lymphocytes and reduces their immunogenicity. Breast cancer is the second most common cause of mortality after lung cancer. Direct evidence linking B7-H1 with cancer has been shown in several malignancies; however, its expression in breast cancer has not been investigated. We used immunohistochemistry to investigate the expression of the B7-H1 molecule in 44 breast cancer specimens and to study its correlation with patients' clinicopathological parameters. The expression of B7-H1 was shown in 22 of 44 patients and was not restricted to the tumor epithelium (15 of 44, 34% in tumor cells), but was also expressed by tumor-infiltrating lymphocytes (TIL; 18 of 44, 41%). Interestingly, intratumor expression of B7-H1 was significantly associated with histologic grade III-negative (P = .012), estrogen receptor-negative (P = .036), and progesterone receptor-negative (P = .040) patients. In addition, the expression of B7-H1 in TIL was associated with large tumor size (P = .042), histologic grade III (P = .015), positivity of Her2/neu status (P = .019), and severe tumor lymphocyte infiltration (P = .001). Taken together, these data suggest that B7-H1 may be an important risk factor in breast cancer patients and may represent a potential immunotherapeutic target using monoclonal antibody against the B7-H1 molecule.

Dendritic cell immunotherapy for breast cancer

Novel adjuvant therapies are urgently needed to complement the existing treatment options for breast cancer. The advent of the use of dendritic cells (DCs) for cancer immunotherapy provides a unique opportunity to overcome the relative non-immunogenic property of breast tumours and address the underlying immunodeficiency. To date, the success of this approach has been limited, possibly due to the targeting of specific tumour antigens that rapidly mutate and, thus, become undetectable to the immune system. A more efficient approach would include preparations encompassing multiple antigens, such as those provided by loading of whole tumour cells or tumour RNA. It is proposed that targeting mammary stem cells responsible for resistance to chemo/immunotherapy, through the expression of a broad array of wild-type and mutated tumour antigens in the context of DCs, will become a mainstay for immunotherapy of breast cancer.

Why do some breast cancer cells remain dormant?

Dormant breast cancer cells are a reality that cannot be overlooked. They may stay dormant either after a spread of cancer cells caused by surgery or after being generated by spontaneous or induced mutations in the course of breast gland growth. Some cases are presented in support of both possibilities, followed by a critical appraisal of the factors that may either keep them dormant or later stimulate their growth into a breast cancer.

Fas Ligand Expression and Its Correlation with Apoptosis and Proliferation in Lobund-Wistar Prostate Carcinomas

OBJECTIVE

The Fas (CD95) interaction with its receptor Fas ligand (FasL) is one of the main mechanisms of cell apoptosis. High expression of FasL has been consistently observed in a variety of human cancers. In this study, we evaluated FasL and its relationship with apoptosis and proliferation in Lobund-Wistar (L-W) cancers. The L-W rat strain develops spontaneous and induced adenocarcinomas in the anterior prostate and seminal vesicles. Although FasL expression has been observed in a subset of human prostate carcinomas, this multistage model allowed in vivo evaluation of subclones of malignant cells with a single genetic susceptibility.

METHODS

Apoptosis was evaluated in spontaneous, induced and transplanted tumors as well as metastasis using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) technique and transmission electron microscopy. Proliferating cell nuclear antigen (PCNA) and FasL expression were detected using immunohistochemistry and analyzed according to the number of positive cells and intensity of staining using a semiquantitive method.

RESULTS

Apoptotic indexes were significantly higher in spontaneous tumors compared to induced (p < 0.008), transplanted tumors (p < 0.0112) and metastases (p < 0.009). TUNEL-positive cells were frequently observed in the leukocytic infiltrate of the stroma in transplanted carcinomas and metastases. These findings were confirmed by electron microscopy. FasL expression was not uniformly localized in L-W carcinomas and its highest expression was observed in transplanted tumors and metastasis (p < 0.005). Moreover, PCNA indices were directly correlated with cancers showing high FasL total scores (Hscores).

CONCLUSIONS

In this model, high FasL expression was associated with cells displaying low apoptotic indexes and high PCNA index. Therefore, analysis of FasL may have clinical relevance in detecting the malignant potential of prostate cancers.

The role of apoptosis in the regulation of trophoblast survival and differentiation during pregnancy

Apoptosis is important for normal placental development, but it may also be involved in the pathophysiology of pregnancy-related diseases. Normal placental development is dependent upon the differentiation and invasion of the trophoblast, the main cellular component of the placenta. Trophoblast apoptosis increases in normal placentas as gestation proceeds, and a greater incidence of trophoblast apoptosis has been observed in pregnancies complicated by preeclampsia or intrauterine growth retardation (IUGR). In response to different stimuli, apoptosis may be initiated extrinsically by the death receptor pathway or intrinsically by the mitochondrial pathway. The central executioners of apoptosis are the caspases, which cleave numerous vital cellular proteins to affect the apoptotic cascade. By inhibiting caspase activation, several endogenous inhibitors, including flice-like inhibitory proteins (FLIPs), inhibitors of apoptosis (IAPs), and antiapoptotic Bcl-2 family members, can prevent further propagation of the death signal. Macrophages present at the maternal-fetal interface may also contribute to trophoblast survival by removing apoptotic cells and producing cytokines and growth factors, which influence the progression of the apoptotic cascade. This review focuses on the role of apoptosis in trophoblast development and differentiation, the molecular mechanisms by which normal trophoblast apoptosis can occur, and how it is regulated to prevent excessive trophoblast apoptosis and possible pregnancy complications.

Down-regulation of Bcl-2 enhances estrogen apoptotic action in long-term estradiol-depleted ER+ breast cancer cells

Postmenopausal women with estrogen receptor positive (ER(+)) breast cancer frequently respond paradoxically to estrogen administration with tumor regression. Using both LTED and E8CASS cells derived from MCF-7 breast cancer cells by long-term estrogen-deprivation, we previously reported that 17beta -estradiol (estradiol) is a powerful, pro-apoptotic hormone which kills the cancer cells through activation of the Fas/FasL death receptor pathway. We postulated that the mitochondrial interactive protein Bcl-2 might play a role in the regulation of estradiol-induced apoptosis in both LTED and E8CASS cells. In this study, we assessed estradiol effects on cell growth, proliferation and apoptosis. Additionally we investigated the effect of estradiol on caspase activation, NF-KB and Bcl-2 expression. The functional role of Bcl-2 in estradiol-induced apoptosis was further studied by knockdown or decrease of Bcl-2 with siRNA. Our results show that estradiol significantly inhibited cell growth primarily through a pro-apoptotic action involving caspase-7 and 9 activations (p < 0.01). Basal Bcl-2 and NF-KB levels were greatly elevated and estradiol decreased NF-KB, but not Bcl-2 expression. Knockdown of Bcl-2 expression with siRNA decreased the levels of this protein by 9 fold (p < 0.01). This reduction markedly sensitized both LTED and E8CASS cells to the pro-apoptotic action of estradiol, leading to a synergistic induction of apoptosis and a concomitant reduction in cell number (p < 0.01). Therefore, down-regulation of Bcl-2 synergistically enhanced estradiol-induced apoptosis in ER(+) postmenopausal breast cancer cells.

Does CD95 have tumor promoting activities?

CD95 (APO-1/Fas) is an important inducer of the extrinsic apoptosis signaling pathway and therapy induced apoptosis of many tumor cells has been linked to the activity of CD95. Changes in the expression of CD95 and/or its ligand CD95L are frequently found in human cancer. The downregulation or mutation of CD95 has been proposed as a mechanism by which cancer cells avoid destruction by the immune system through reduced apoptosis sensitivity. CD95 has therefore been viewed as a tumor suppressor. Furthermore, increased CD95L concentration in tumor patients has been linked to tumor cells killing infiltrating lymphocytes in a process called "the tumor counter-attack". Recent data have illuminated unknown activities of CD95 in tumor cells with downregulated or mutated CD95 in the presence of increased CD95L. Under these conditions the stimulation of CD95 signals nonapoptotic pathways, activating NF-kappaB and MAP kinases for example, which may result in the induction of tumorigenic or prosurvival genes. A new model of CD95 functions is proposed in which CD95 is converted from a tumor suppressor to a tumor promotor by a single point mutation in one of the CD95 alleles, a situation frequently found in advanced human cancer, resulting in apoptosis resistance and activation of tumorigenic pathways.

Antiestrogens, aromatase inhibitors, and apoptosis in breast cancer

Antiestrogens have been the therapeutic agents of choice for breast cancer patients whose tumors express estrogen receptors, regardless of menopausal status. Unfortunately, many patients will eventually develop resistance to these drugs. Antiestrogens primarily act by preventing endogenous estrogen from activating estrogen receptors and promoting cell growth, which can ultimately lead to tumor cell death. Understanding the mechanisms by which antiestrogens cause cell death or apoptosis is critical to our efforts to develop ways to circumvent resistance. This article focuses on antiestrogen-induced apoptosis both in vitro and in vivo. We review the clinical utility of both antiestrogens and aromatase inhibitors and their apoptogenic mechanisms in cell culture models. Among the key signaling components discussed are the roles of Bcl-2 family members, several cytokines, and their receptors, p53, nuclear factor kappa B (NFkappaB), IRF-1, phosphatidylinositol 3-kinase (PI3K)/Akt, and specific caspases. Finally, we discuss the evidence supporting a role for apoptotic defects in acquired and de novo antiestrogen resistance.

Paclitaxel treatment of breast cancer cell lines modulates Fas/Fas ligand expression and induces apoptosis which can be inhibited through the CD40 receptor

OBJECTIVE

Cytotoxic chemotherapy of advanced breast cancer is frequently complicated by drug resistance. Our goal was to define the role of the apoptosis-regulating receptors Fas (CD95) and CD40 in the chemosensitivity of breast cancer.

METHODS

The sensitivity of four breast cancer cell lines to paclitaxel and mitoxantrone was evaluated using an ATP-based cell viability assay. After verification of apoptosis by annexin V staining and TUNEL assay, cell lines were characterized regarding their constitutive expression of both surface and soluble (s)Fas (CD95) and Fas ligand (Fas-L). The role of the Fas/Fas-L system and different caspases was assessed by blocking drug-mediated apoptosis with specific antibodies. Finally, the paclitaxel sensitivity of the CD40-negative cell line KS was compared to that of its CD40-positive transfectant KS-CD40.

RESULTS AND CONCLUSION

While the cytotoxic effect of mitoxantrone did not correlate with Fas expression, the results presented here suggest some involvement of the Fas/Fas-L system in paclitaxel-induced apoptosis. Cell lines with constitutive expression of Fas/sFas demonstrated a higher sensitivity to paclitaxel than Fas-negative cells. Incubation with paclitaxel led to a measurable downregulation of the expression of both soluble and surface Fas receptor in these cells. Interestingly, stimulation of the CD40 receptor inhibited paclitaxel-induced apoptosis in the transfected cell line KS-CD40, suggesting a role of this receptor in the modulation of chemosensitivity.

The Fas/Fas ligand system and cancer: immune privilege and apoptosis

The Fas/FasL system has been suggested to play an important role in the establishment of immune privilege status for tumors by inducing Fas-mediated apoptosis in tumor-specific lymphocytes. However, the role of cell-surface expressed FasL in tumor cell protection has recently become controversial. Our laboratory has focused on the study of the role of the Fas/FasL system in the normal tissue remodeling of the female reproductive tract and in immune-privileged organs. Our studies have demonstrated a connection between sex hormones and the regulation of the Fas/FasL pathway in immune and reproductive cells. More recently, we have investigated the resistance of tumor cells to Fas-mediated apoptosis. We have also characterized a new form of FasL, different from the classical membranal form, which is secreted by ovarian cancer cells. In this review we describe the main techniques used in these studies.

Activated platelets rapidly up-regulate CD40L expression and can effectively mature and activate autologous ex vivo differentiated DC

Background DC are a promising immunotherapeutic for treatment of infectious/malignant disease. For clinical trials, immature DC generated from precursor cells such as monocytes, using serum-free media containing GM-CSF and IL-4, can be matured with specific cytokines/factors. CD40 ligand (CD40L) plays an important role in DC activation/maturation but is not available for clinical applications. These studies evaluated the feasibility of using activated platelets with elevated CD40L surface expression to stimulate autologous DC maturation. Methods Pilot and clinical scale studies were executed using magnetic/centrifugal separation. Monocyte precursors were differentiated to immature DC with GM-CSF and IL-4 and the ability of activated autologous platelets to mature these cells was evaluated on the basis of phenotype and function. Results In small-scale studies, DC cultures stimulated with activated autologous platelets (CD40L-AP), tumor necrosis factor-alpha (TNF-alpha) or soluble CD40L (sCD40L) up-regulated expression of phenotype markers indicative of activation and maturation. CD86 expression was significantly enhanced (P<0.05) by stimulation with either CD40L-AP (75.5+/-14.5%) or sCD40L (80.5%+/-5.3%) compared with immature DC (55.2+/-14.8%), as were CD80 and CD83. Similarly, in large-scale studies using Isolex 300I to enrich for monocytes and platelets for DC generation/maturation on a clinical scale, stimulation with CD40L-AP increased CD86 and CD80 expression as well as the ability to stimulate allogeneic lymphocytes compared with control cultures. Discussion These results demonstrate that thrombin-activated platelets express CD40L and are effective at inducing matured DC with potent immunogenic activity. Furthermore, these studies demonstrate the feasibility of this approach for clinical immunotherapeutic interventions.

Chromosome 17p13.2 transfer reverts transformation phenotypes and fas-mediated apoptosis in breast epithelial cells

Transformation of the human breast epithelial cells (HBEC) MCF-10F with the carcinogen benz(a)pyrene (BP) into BP1-E cells resulted in the loss of the chromosome 17 p13.2 locus (D17S796 marker) and formation of colonies in agar-methocel (colony efficiency (CE)), loss of ductulogenic capacity in collagen matrix, and resistance to anti-Fas monoclonal antibody (Mab)-induced apoptosis. For testing the role of that specific region of chromosome 17 in the expression of transformation phenotypes, we transferred chromosome 17 from mouse fibroblast donors to BP1-E cells. Chromosome 11 was used as negative control. After G418 selection, nine clones each were randomly selected from BP1-E-11neo and BP1-E-17neo hybrids, respectively, and tested for the presence of the donor chromosomes by fluorescent in situ hybridization and polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) analyses. Sensitivity to Fas Mab-induced apoptosis and evaluation of transformation phenotype expression were tested in MCF-10F, BP1-E, and nine BP1-E-11neo and BP1-E-17neo clones each. Six BP1-E-17neo clones exhibited a reversion of transformation phenotypes and a dose dependent sensitivity to Fas Mab-induced apoptosis, behaving similarly to MCF-10F cells. All BP1-E-11neo, and three BP1-E-17neo cell clones, like BP1-E cells, retained a high CE, loss of ductulogenic capacity, and were resistant to all Fas Mab doses tested. Genomic analysis revealed that those six BP1-E-17neo clones that were Fas-sensitive and reverted their transformed phenotypes had retained the 17p13.2 (D17S796 marker) region, whereas it was absent in all resistant clones, indicating that the expression of transformation phenotypes and the sensitivity of the cells to Fas-mediated apoptosis were under the control of genes located in this region.

Resistance to Fas-mediated cell death in BeWo and NJG choriocarcinoma cell lines: implications in immune privilege

OBJECTIVE

An immune privileged site occurs when the allogenic tissue grafts have the propensity for prolonged survival in the host tissue. In this context, the survival and proliferation of malignant trophoblasts in the gravid uterus are currently unclear. In a previous study, we documented that Fas and FasL are coexpressed in choriocarcinoma [Gynecol. Oncol. (2003)]. This study was conducted to examine the role of the Fas/FasL pathway in immune privilege of BeWo and NJG choriocarcinoma cells in culture.

METHODS

The ability of anti-Fas mAb (CH-11) to sensitize choriocarcinoma cell lines to Fas-mediated cytotoxicity was assessed by MTT assays. Coculture experiments with Fas-sensitive Jurkat cells were used to demonstrate functional FasL from choriocarcinoma. RT-PCR was used to assess the expression of cFLIP.

RESULTS

The mean cell viability of BeWo and NJG cells declined to about 58 and 63% compared to controls after 72 h of culture in the presence of anti-Fas mAb (CH-11) while the Fas-sensitive Jurkat cells showed viability of only 10%. This resistance to Fas-mediated apoptosis in choriocarcinoma cells is reversed in the presence of cycloheximide (0.5 micro g/ml) which further decreased the viability to 36 and 32%, respectively, at a dose of 300 ng/ml (P < 0.05). The observed resistance to Fas-mediated apoptosis therefore could be attributed to the short-lived endogenous inhibitor, cFLIP as demonstrated by the RT-PCR technique. In coculture experiments, FasL from choriocarcinoma cells induced apoptosis in the Fas-sensitive Jurkat cells, thereby indicating the capacity to evade immune attack.

CONCLUSIONS

Decreased sensitivity to Fas-mediated apoptosis and counterattacking the lymphocytes may impart immune privilege in these malignant trophoblasts for prolonged survival in the host.

Immunotherapy and prostate cancer

Prostate cancer is the second leading cause of cancer death in the US, largely because of the limitations of our current therapeutic options, especially once the cancer has metastasized. Investigators have long sought new therapeutic modalities such as angiogenesis inhibitors, vaccines, and gene therapy, among others. It appears that a combination approach will be required to cure the majority of malignancies. Immunotherapy for prostate cancer appears feasible and a likely therapeutic modality in the armamentarium. Unfortunately, further research in basic immunology and the interaction of the immune system with other forms of therapy is needed. Many obstacles exist in immunotherapy, including vector design, tumouricidal specificity, and tumor evasion, which will have to be overcome in order to realize the maximum therapeutic benefit from this treatment modality.

Phenoxodiol--an isoflavone analog--induces apoptosis in chemoresistant ovarian cancer cells

Interference with the innate apoptotic activity is a hallmark of neoplastic transformation and tumor formation. In this study we characterize the cytotoxic effect of phenoxodiol, a synthetic anticancer drug analog of genestein, and demonstrate the mechanism of action by which phenoxodiol affects the components of the Fas apoptotic pathway on ovarian cancer cells. Primary ovarian cancer cells, isolated from ascitic fluids of ovarian cancer patients, resistant to conventional chemotherapy, undergo apoptosis following phenoxodiol treatment. This effect is dependent upon the activation of the caspase system, inhibiting XIAP, an inhibitor of apoptosis, and disrupting FLICE inhibitory protein (FLIP) expression through the Akt signal transduction pathway. We suggest that phenoxodiol is an efficient inducer of cell death in ovarian cancer cells and sensitizes the cancer cells to Fas-mediated apoptosis. We identified FLIP and XIAP signalling pathways as key factors regulating the survival of ovarian cancer cells. These findings demonstrate a novel nontoxic drug that controls FLIP/XIAP function and has the potential to eliminate tumor cells through Fas-mediated apoptosis.

Role of the Fas/Fas ligand system in female reproductive organs: survival and apoptosis

For centuries, the question of "whether there is life after death" has intrigued the mind of philosophers and the same question fascinates researchers in the field of apoptosis today. The death of a cell is by no means the end of the story. On the contrary, growing evidence suggests that the clearance of apoptotic bodies by macrophages is an important regulatory component in tissue renewal. Without death by apoptosis, the life of reproductive tissues and their function would not be possible. The survival signals that counteract cell death also prepare the cells for apoptosis, and dead cells are important stimuli for tissue survival. The Fas/Fas ligand system is an important mediator of apoptosis and is an excellent example of this apparently contradictory phenomenon.

Differential regulation and function of the Fas/Fas ligand system in human trophoblast cells

Trophoblast rejection, which is characterized by increased apoptosis, is mediated by T helper (Th)-1, or proinflammatory, cytokines, whereas Th-2, or anti-inflammatory, cytokines confer immune protection and facilitate implantation. We investigated the role of both types of cytokines on the expression and function of the Fas/Fas ligand (FasL) apoptotic pathway in trophoblast cells. First-trimester human trophoblast primary-culture cells as well as A3 and HTR/8 trophoblast cell lines were treated with proinflammatory cytokines such as interferon-gamma (IFN-gamma) and tumor necrosis factor alpha (TNFalpha) and with the anti-inflammatory cytokines interleukin (IL)-6 and IL-10. Sensitivity to Fas-mediated apoptosis was measured using an activating anti-Fas monoclonal antibody. Cell viability was evaluated using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) and CellTiter 96 assay. Fas/FasL mRNA and protein expression levels were determined using reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. Trophoblast cells normally express FasL, but low levels of Fas, and they are resistant to Fas-mediated apoptosis. IFN-gamma and TNFalpha promote Fas expression and sensitivity, whereas IL-6 and IL-10 increase the resistance of trophoblast cells to Fas-mediated apoptosis. Furthermore, IL-10 treatment activates FLICE-like inhibitory protein (FLIP), a downstream inhibitor of Fas apoptotic signaling. Although trophoblast cells express Fas, susceptibility to Fas does not necessarily correlate with its expression. In this study, we demonstrate that Th-2 cytokines increase the resistance of trophoblast cells to Fas-mediated apoptosis either by inhibiting Fas expression or by inducing FLIP activation. This "trophoblast-cytokine-Fas/FasL triad" determines the ability of the Fas/FasL system to regulate trophoblast viability and, consequently, the success or failure of pregnancy.

RCAS1 is associated with ductal breast cancer progression

RCAS1/EBAG9 (receptor-binding cancer antigen expressed on SiSo cells/ estrogen receptor-binding fragment-associated gene 9), an estrogen-transcribed protein, has been shown to be expressed in a wide variety of cancers, including uterine, ovarian, and lung cancer cells. Soluble and membranous RCAS1 proteins may play a role in the immune escape of tumor cells by promoting T lymphocyte inhibition of growth and apoptosis. In the present report, the presence of RCAS1 was revealed in human ductal breast cancer biopsies by immunohistochemistry. Its cytoplasmic expression was exhibited in cancer cells obtained from tumor biopsies and in breast cancer cell lines. RCAS1 significantly correlated with tumor grade. In addition, RCAS1 was identified in MCF7 culture supernatants. Those observations suggest that RCAS1 is a new marker for breast cancer progression and a possible mechanism for breast cancer immune escape.

Normal breast epithelial cells induce apoptosis of breast cancer cells via Fas signaling

Fas/Fas ligand (Fas L) death pathway is an important mediator of apoptosis. Deregulation of Fas pathway is reported to be involved in the immune escape of breast cancer and the resistance to anti-cancer drugs. In this study, we demonstrated that conditioned medium by normal breast epithelial cells (NBEC-CM) induced apoptosis of MCF-7 and T-47D Fas-sensitive cells but had no effect on MDA-MB-231 Fas-resistant cells. Inhibition of PI3 kinase or NF-kappaB by specific inhibitors or transient transfections restored the sensitivity of MDA-MB-231 cells to NBEC-induced apoptosis. Moreover, the constitutive activation of NF-kappaB was controlled by PI3 kinase because inhibition of PI3 kinase reduced NF-kappaB activity. Inducible activation of NF-kappaB rendered MCF-7 cells resistant to NBEC-CM- and Fas agonist antibody-triggered apoptosis. Therefore, constitutive or inducible activation of PI3 kinase and/or NF-kappaB in breast cancer cells rendered them resistant to NBEC-triggered apoptosis. In addition, Fas neutralizing antibody and dominant negative Fas abolished NBEC-triggered apoptosis. Western blot and confocal microscopy analysis showed an increase of membrane Fas/Fas L when cells were induced into apoptotis by NBEC-CM. Taken together, these data show that NBEC induced apoptosis in breast cancer cells via Fas signaling.

Fas counterattack in cholangiocarcinoma: A mechanism for immune evasion in human hilar cholangiocarcinomas

AIM: To investigate FasL expression in hilar cholangiocarcinoma tissues and cultured cholangiocarcinoma cells, and to assess its ability to induce apoptosis.

METHODS: We studied the expression of FasL by human hilar cholangiocaroinomas tissues by immunohistochemistry, and the QBC939 cholangiocarcinoma cell line by RT-PCR, immunohistochemistry, and Western Blot. TUNEL and flow cytometry were used to detect apoptotic cells.

RESULTS: Prevalent expression of FasL was detected in 39 resected hilar cholangiocarcinoma tissues. TUNEL staining disclosed a high level of cell death among lymphocytes infiltrating FasL positive areas of tumor. FasL mRNA and protein expressions in cholangiocarcinoma cells could induce Jurkat cells.

CONCLUSION: Hilar cholangiocarcinomas may elude immunological surveillance by inducing, via Fas/FasL system, the apoptosis of activated lymphocytes.

17alpha-methyl testosterone is a competitive inhibitor of aromatase activity in Jar choriocarcinoma cells and macrophage-like THP-1 cells in culture

17alpha-methyl testosterone is a synthetic androgen with affinity for the androgen receptor. 17alpha-methyl testosterone is used widely as a component of hormone replacement therapy. Previous reports have indicated that contrary to testosterone, 17alpha-methyl testosterone is not aromatized. However, 17alpha-methyl testosterone still could affect local estrogen formation by regulating aromatase expression or by inhibiting aromatase action. Both possibilities have important clinical implications. To evaluate the effect of 17alpha-methyl testosterone on the expression and activity of aromatase, we tested the choriocarcinoma Jar cell line, a cell line that express high levels of P450 aromatase, and the macrophage-like THP-1 cells, which express aromatase only after undergoing differentiation. We found that in both cell lines, 17alpha-methyl testosterone inhibits aromatase activity in a dose-related manner. The curve of inhibition parallels that of letrozole and gives complete inhibition at 10(-4) M 17alpha-methyl testosterone, determined by the tritium release assay. 17alpha-methyl testosterone does not have detectable effects on aromatase RNA and protein expression by Jar cells. Undifferentiated THP-1 cells had no aromatase activity and showed no effect of 17alpha-methyl testosterone, but differentiated THP-1 (macrophage-like) cells had a similar inhibition of aromatase activity by 17alpha-methyl testosterone to that seen in Jar cells. The Lineweaver-Burke plot shows 17alpha-methyl testosterone to be a competitive aromatase inhibitor. Our results show for the first time that 17alpha-methyl testosterone acts as an aromatase inhibitor. These findings are relevant for understanding the effects of 17alpha-methyl testosterone as a component of hormone replacement therapy. 17alpha-methyl testosterone may, as a functional androgen and orally active steroidal inhibitor of endogenous estrogen production, also offer special possibilities for the prevention/treatment of hormone-sensitive cancers.

Soluble Fas (CD95) is a prognostic factor in patients with metastatic breast cancer undergoing high-dose chemotherapy and autologous stem cell transplantation

The Fas/Fas ligand (FasL) system plays an important role in cellular apoptosis and is involved in cancer cell death induced by the immune system and anticancer drugs. Increased serum levels of soluble Fas (sFas) are associated with a number of different disease states and with tumor progression and metastasis in patients. In this study, we examined the plasma levels of sFas in 94 women with metastatic breast cancer undergoing high-dose chemotherapy (HDCT) treatment with autologous stem cell transplantation (ASCT) using a quantitative enzyme-linked immunosorbent assay (ELISA) method. Thirty-one patients (31/94, 33%) had plasma sFas levels greater than the optimum cut point of 1.90 ng/ml (median 2.47, range 1.98-13.54 ng/ml) and were designated as sFas positive. Sixty-three patients (63/94, 67%) had sFas levels below 1.90 ng/ml (median 1.14, range 0.47-1.89 ng/ml). In univariate analysis, patients with sFas-positive status, HER-2 overexpression, and the presence of liver metastases had a significantly shorter time to disease progression (PFS) and significantly decreased overall survival (OS). Multivariable analysis (Cox proportional hazards model) for PFS determined that sFas status significantly predicted disease progression (p = 0.004) with an adjusted hazard ratio (HR) of 2.0 (95% CI, 1.3-3.3). HER-2 status and liver metastases were also significant independent predictors of disease progression (p < 0.001) for both. sFas level was also an independent prognostic factor for OS with an adjusted HR of 2.0 (p = 0.006; 95% CI, 1.2-3.4). HER-2 status and liver metastases also remained highly significant independent prognostic factors for OS (HER-2: p < 0.001, HR 2.3, and liver metastases: p = 0.001, HR 2.7). In conclusion, these results suggest that plasma levels of sFas may be a valuable clinical prognostic factor in predicting outcome (PFS and OS) for patients with metastatic breast cancer undergoing HDCT with ASCT.