Demethoxycurcumin Suppresses Human Brain Glioblastoma Multiforme GBM 8401 Cell Xenograft Tumor in Nude Mice In Vivo.

Demethoxycurcumin (DMC), a derivate of curcumin, has been shown to induce apoptotic cell death in human glioblastoma multiforme GBM 8401 cells via cell cycle arrest and induction of cell apoptosis. However, there is no report showing DMC suppresses glioblastoma multiforme cells in vivo. In the present study, we investigated the effects of DMC on GBM8401 cells in vivo. At first, we established a luciferase-expressing stable clone named GBM 8401/luc2. Second, mice were inoculated subcutaneously with GBM 8401/luc2 cells to generate a xenograft tumor mice model. After inoculation, tumor volume reached 100-120 mm3, and all mice were randomly divided into three groups: Group I was treated with 110 µL phosphate-buffered solution (PBS) containing 0.1% dimethyl sulfoxide, Group II with 30 mg/kg of DMC, and Group III with 60 mg/kg of DMC. Mice from each group were given the oral treatment of DMC by gavage for 21 days. The body weight and tumor volume were recorded every 3 days. DMC significantly decreased the tumor volumes, and 60 mg/kg treatment showed a higher decrease in tumor volumes than that of 30 mg/kg, However, DMC did not affect the body weights. The photons emitted from mice tumors were detected with Xenogen IVIS imaging system, DMC at both doses decreased the total photon flux and 60 mg/kg treatment of DMC has low total photon flux than that of 30 mg/kg. The tumor volumes and weights in 60 mg/kg treatment of DMC were lower than that of 30 mg/kg. Immunohistochemical analysis was used to measure protein expression of tumors and results showed that DMC treatment led to lightly staining with anti-Bcl-2 and -XIAP and 60 mg/kg treatment of DMC has lighter staining with anti-Bcl-2 and -XIAP than that of 30 mg/kg. The higher dose (60 mg/kg) of DMC has higher signals of cleaved-caspase-3 than that of the lower dose (30 mg/kg). Furthermore, the hematoxylin and eosin (H&E) staining of liver tissues showed no significant difference between DMC-treated and control-groups. Overall, these observations showed that DMC suppressed tumor properties in vivo and DMC may be used against human glioblastoma multiforme in the future.

Quantitative biochemical characterization and biotechnological production of caspase modulator, XIAP: Therapeutic implications for apoptosis-associated diseases.

BACKGROUND: Regulating apoptosis is a common and essential therapeutic strategy for cancer and neurodegenerative disorders. Based on basic studies of apoptotic mechanisms, various researches have attempted to overcome the pathogenesis of such diseases by activating or inhibiting apoptosis. Generally, the biochemical characteristics of the target molecules should be evaluated along with understanding of their mechanisms of action during drug development. Among apoptotic regulators, XIAP serves as a potent negative regulator to block apoptosis through the inhibition of caspase (CASP)-9 and -3/7. Although XIAP is an attractive target with such apoptotic-modulating property, biochemical and biophysical studies of XIAP are still challenging. METHODS: In this study, the CASP-9 and -3/7 inhibitors XIAP, 242Δ and Δ230 were prepared using the pGEX expression system and biochemically characterized. RESULTS: These inhibitors were expressed in Escherichia coli at a concentration of ≥20 mg/L culture under a native condition with 0.01 mM IPTG induction. Notably, using a simple and rapid affinity purification technique, these CASP-9 and -3/7 inhibitors have been purified, yielding ≥5 mg/L culture at approximately 90% purity. CONCLUSIONS: We have determined that HtrA2 specifically binds to the BIR2 and BIR3 of XIAP at a 1:1 molecular ratio. Moreover, in vitro cell-free CASP-9 and -3/7 activation-apoptosis assays have demonstrated that these purified XIAP proteins dramatically inhibit CASP-9 and -3/7 action. GENERAL SIGNIFICANCE: Our system is suitable for biochemical studies, such as quantitation of the number of molecules acting on the apoptosis regulation, and provides a basis and insights that can be applied to the development of therapeutic agents for neurodegenerative disorders and cancer.

The expression and significance of XIAP and C-jun on Condyloma acuminatum.

Objective of the study was to investigate the expression and significance of XIAP and c-jun in Condyloma acuminatum. The immunohistochemistry SABC method was adopted to detect the expression of XIAP and c-jun in Condyloma acuminatum. The positive expression rate of XIAP and c-jun in Condyloma acuminatum was 80% (32/40) and 90% (36/40) separately and the intensity of expression was usually ++ ~ +++. While in control group, the positive expression rate of XIAP and c-jun was 27.8% (5/18) and 16.7 % (3/18) separately, and the intensity of expression was - ~ ++. There was statistical significance of the positive expression rate and the expression intensity of XIAP and c-jun between the two groups (P<0.05). Besides, the positive correlation existed between expression of XIAP and c-jun (r=0.306 P<0.01). The over-expression of XIAP and c-jun in Condyloma acuminatum may be associated with the growth of Condyloma acuminatum.

Expression of apoptosis regulating proteins identifies stage II and III colon cancer patients with high risk of recurrence.

BACKGROUND AND OBJECTIVES: Deregulation of apoptosis related genes may be associated with poor outcome in cancer. Aim of the present study was to investigate the prognostic role of expression levels of apoptosis related proteins in stage II and III colon cancer. METHODS: From tumor samples of 386 stage II and III colon cancer patients, DNA was isolated and tissue microarrays were constructed. Expression of Bcl-2, Bcl-X, BAX, XIAP, Fas, FasL and c-FLIP was evaluated and PCR-based microsatellite instability analysis was performed. RESULTS: High FasL expressing tumors were associated with high disease recurrence rates in stage II colon cancer patients overall, as was low Bcl-X expression in microsatellite stable stage II patients. In stage II patients, a multivariable model based on FasL and Bcl-XL expression revealed a significant association with disease free survival (DFS). In stage III colon cancer patients, low Bcl-2, low BAX and low Fas expression levels were associated with worse outcome. In these patients a multivariable model based on angioinvasion and Bcl-2, Fas and FasL expression was significantly associated with DFS. CONCLUSIONS: Stage II patients with low Bcl-X and high FasL protein expression levels and stage III patients with low Fas, high FasL and low Bcl-2 expression could be considered as high risk for disease recurrence.

Centroblastic diffuse large B cell lymphoma displays distinct expression pattern and prognostic role of apoptosis resistance related proteins.

Centroblastic diffuse large B cell lymphoma (DLBCL) samples were analyzed by immunohistochemistry to evaluate the expression of p53, Bcl-2, Survivin, XIAP, and Ki-67. Survivin was the only protein which expression exhibited a trend for impact in progression-free (p = .077) and overall survival (p = .054). In the Mann-Whitney test, Survivin expression correlated with a negative overall survival (p = .045). These results appeared to be intimately related to Survivin cytoplasmic localization. Moreover, the anti-apoptotic proteins Bcl-2 and Survivin were less frequent in centroblastic DLBCL. Our results indicate that centroblastic DLBCL may be a disease with characteristic biology and clinical course and, therefore, specific prognostic factors.

Relationship between apoptosis and proliferation in granulosa and theca cells of cystic follicles in sows.

To investigate the causes of the occurrence and persistence of porcine cystic follicles, we evaluated the apoptosis and proliferation of follicular cells in these cysts. Apoptotic frequencies were examined by TUNEL assay and the expression of apoptosis regulators (XIAP, bax, bc1-2 and caspase-3) by immunohistochemistry, Western blotting and real-time quantitative PCR; cell proliferation activity was evaluated by PCNA immunohistochemistry and proliferation of in vitro cultured granulosa and theca cells. The low apoptotic frequency and weak proliferative activity were found in cystic follicles. Low frequency of apoptosis might be associated with decreased amounts of apoptotic-related factors (bax and caspase-3) and increased amounts of anti-apoptotic factors (XIAP and bcl-2) in cystic follicles. Significantly lower proliferation activity was detected in granulosa and theca cells from cystic follicles, and lesser PCNA-positive cells were found in cystic follicles. Our results indicate that the programmed cell death and cell proliferation system were altered in cystic follicles. The disorder between apoptosis and proliferation was responsible for maintaining a static condition without degeneration, which leads to the long-term persistence of follicles. These findings provide important novel insights into the pathogenesis of follicular cysts in sows.

Antiproliferative effect of chrysin on anaplastic thyroid cancer.

BACKGROUND: Anaplastic thyroid cancer (ATC) is an undifferentiated, aggressive malignancy, for which there are no effective therapies. Though ATCs only make up less than 2% of all thyroid cancer cases, they represent over half of the thyroid cancer-related deaths. Chrysin, a natural flavonoid, has recently been reported as a potential anti-cancer agent. However, the effect of this compound on ATC cells is not known. Thus, in this study, we evaluated the antiproliferative nature of chrysin in ATC cells. METHODS: HTH7 and KAT18 cells, derived from patients with ATC, were treated with chrysin (25-50 µM) for up to 6 d. Cell proliferation was measured every 2 d using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Western blot analysis for molecular makers of apoptosis was carried out to investigate the effect and mechanism of Chrysin on ATC. RESULTS: Chrysin inhibited proliferation of HTH7 and KAT18 in a dose- and time-dependent manner. HTH7 and KAT18 cells with Chrysin treatment showed a significant increase in cleaved caspase-3, cleaved PolyADP Ribose Polymerase (PARP), along with a decrease in cyclin D1, Mcl-1, and XIAP. Furthermore, the ratio of Bax to Bcl-2 expression in ATC cells revealed an increase after the treatment. CONCLUSIONS: Chrysin inhibits growth in ATC cells via apoptosis in vitro. Therefore, the natural flavonoid chrysin warrants further clinical investigation as a new potential drug for the treatment for ATC.

XAF1 as a prognostic biomarker and therapeutic target in pancreatic cancer.

XAF1 (X chromosome-linked inhibitor of apoptosis [XIAP]-associated factor 1) is a novel XIAP modulator that negatively regulates the anti-apoptotic effects of XIAP and sensitizes cells to other cell death triggers. It has been reported to be downregulated in a variety of human cancer cell lines. However, the role of XAF1 in pancreatic carcinogenesis remains unclear. In the present study, we investigated the prognostic values of XAF1 expression and its regulation in cancer cell growth and apoptosis both in vitro and in vivo. From the immunohistochemistry staining of tissue microarray, 40 of 89 (44.9%) pancreatic specimens showed low levels of XAF1 expression. Statistical analysis suggested the downregulation of XAF1 was significantly correlated with tumor staging (P = 0.047) and those patients with low XAF1 levels had shorter survival times (P = 0.0162). Multivariate analysis indicated that XAF1 expression was an independent prognostic indicator of the survival of patients with pancreatic cancer (P = 0.007). Furthermore, we found that restoration of XAF1 expression mediated by Ad5/F35 virus suppressed cell proliferation and induced cell cycle arrest and apoptosis, accompanied by the activation of caspases 3, 8, and 9 and poly(ADP-ribose) polymerase as well as increased level of cytochrome c and Bid cleavage. Notably, XAF1 restoration robustly decreased survivin expression rather than XIAP. In addition, in vivo s.c. xenografts from Ad5/F35-XAF1 treatment, which showed less cellular proliferation and enhanced apoptosis, were significantly smaller than those from control groups. Our findings document that XAF1 is a valuable prognostic marker in pancreatic cancer and could be a potential candidate for cancer gene therapy.

Combined analysis of cell growth and apoptosis-regulating proteins in HPVs associated anogenital tumors.

BACKGROUND: The clinical course of human papillomavirus (HPV) associated with Bowenoid papulosis and condyloma acuminatum of anogenital tumors are still unknown. Here we evaluated molecules that are relevant to cellular proliferation and regulation of apoptosis in HPV associated anogenital tumors. METHODS: We investigated the levels of telomerase activity, and inhibitor of apoptosis proteins (IAPs) family (c-IAP1, c-IAP2, XIAP) and c-Myc mRNA expression levels in 20 specimens of Bowenoid papulosis and 36 specimens of condyloma acuminatum in anogenital areas. Overall, phosphorylated (p-) AKT, p-ribosomal protein S6 (S6) and p-4E-binding protein 1 (4EBP1) expression levels were examined by immunohistochemistry in anogenital tumors both with and without positive telomerase activity. RESULTS: Positive telomerase activity was detected in 41.7% of Bowenoid papulosis and 27.3% of condyloma acuminatum compared to normal skin (p < 0.001). In contrast, the expression levels of Bowenoid papulosis indicated that c-IAP1, c-IAP2 and XIAP mRNA were significantly upregulated compared to those in both condyloma acuminatum samples (p < 0.001, p < 0.001, p = 0.022, respectively) and normal skin (p < 0.001, p = 0.002, p = 0.034, respectively). Overall, 30% of Bowenoid papulosis with high risk HPV strongly promoted IAPs family and c-Myc but condyloma acuminatum did not significantly activate those genes. Immunohistochemically, p-Akt and p-S6 expressions were associated with positive telomerase activity but not with p-4EBP1 expression. CONCLUSION: Combined analysis of the IAPs family, c-Myc mRNA expression, telomerase activity levels and p-Akt/p-S6 expressions may provide clinically relevant molecular markers in HPV associated anogenital tumors.

XIAP expression is post-transcriptionally upregulated in childhood ALL and is associated with glucocorticoid response in T-cell ALL.

BACKGROUND: Resistance to glucocorticoid induced apoptosis is one of the major risk factors for relapse and poor outcome in childhood acute lymphoblastic leukemia (ALL). Overexpression of X-linked inhibitor of apoptosis protein (XIAP) has been shown to be associated with chemotherapy resistance in several malignancies. PROCEDURE: XIAP protein and mRNA expression were determined in leukemic blasts of 51 childhood ALL patients and normal bone marrow mononuclear cells. XIAP expression was correlated with glucocorticoid response and outcome. RESULTS: XIAP protein but not mRNA expression was found to be highly increased in childhood ALL compared to control bone marrow mononuclear cells (MNC) (median: 3.5 vs. 0.14 ng/10(5) MNC, P < 0.0001) indicating a post-transcriptional regulation of XIAP expression. In patients with T-cell ALL, poor prednisone response was associated with increased XIAP expression (median: 2.8 in good vs. 5.8 in poor responders; P = 0.005). Similarly, T-cell ALL patients suffering adverse events showed higher initial XIAP levels than patients in continuous complete remission (CCR) (median: 2.7 in patients in CCR vs. 5.6 in patients suffering adverse events; P = 0.007). XIAP inhibition using the low-molecular-weight SMAC mimetic LBW242 resulted in a significant increase of prednisone-induced apoptosis in vitro. CONCLUSION: In childhood ALL compared to control bone marrow, the expression of the apoptosis inhibitor XIAP is highly increased by post-transcriptional regulation. The association with poor in vivo glucocorticoid response and outcome in T-cell ALL suggests XIAP inhibition as a promising novel approach for the treatment of resistant ALL.

Curcumin inhibits prosurvival pathways in chronic lymphocytic leukemia B cells and may overcome their stromal protection in combination with EGCG.

PURPOSE: Chronic lymphocytic leukemia (CLL) is incurable with current chemotherapy treatments. Curcumin (diferuloylmethane), an active ingredient in the spice turmeric, inhibits tumor metastasis, invasion, and angiogenesis in tumor cell lines. We evaluated the effects of curcumin on the viability of primary CLL B cells and its ability to overcome stromal mediated protection. EXPERIMENTAL DESIGN: The in vitro effect of curcumin on primary CLL B cells was evaluated using fluorescence activated cell sorter analysis and Western blotting. For some experiments, CLL B cells were cocultured with human stromal cells to evaluate the effects of curcumin on leukemia cells cultured in their microenvironment. Finally, the effect of curcumin in combination with the green tea extract epigallocatechin-3 gallate (EGCG) was evaluated. RESULTS: Curcumin induced apoptosis in CLL B cells in a dose-dependent (5-20 micromol/L) manner and inhibited constitutively active prosurvival pathways, including signal transducers and activators of transcription 3 (STAT3), AKT, and nuclear factor kappaB. Moreover, curcumin suppressed expression of the anti-apoptotic proteins Mcl-1 and X-linked inhibitor of apoptosis protein (XIAP), and up-regulated the pro-apoptotic protein BIM. Coculture of CLL B cells with stromal cells resulted in elevated levels of STAT3, increased expression of Mcl-1 and XIAP, and decreased sensitivity to curcumin. When curcumin was administered simultaneously with EGCG, antagonism was observed for most patient samples. In contrast, sequential administration of these agents led to substantial increases in CLL B-cell death and could overcome stromal protection. CONCLUSIONS: Curcumin treatment was able to overcome stromal protection of CLL B cells on in vitro testing and to synergize with EGCG when administered in a sequential fashion. Additional evaluation of curcumin as a potential therapeutic agent for treatment of CLL seems warranted.

Expression of X-linked inhibitor of apoptosis protein in human colorectal cancer and its correlation with prognosis.

BACKGROUND: X-linked inhibitor of apoptosis protein (XIAP) is a member of the inhibitor of apoptosis family of proteins and deregulation of XIAP can result in tumorigenicity. The objective of this study was to evaluate the prognostic significance of XIAP expression in colorectal cancer (CRC). METHODS: RT-PCR was performed to detect the expression of XIAP mRNA in CRC cells and tissues. The expression of XIAP protein in tissues was measured by immunohistochemistry. The correlation of XIAP expression with clinicopathologic factors and prognosis of CRC patients was evaluated. RESULTS: CRC cells showed significantly higher levels of XIAP mRNA expression than normal human intestinal epithelial cell. The expression level of XIAP mRNA in CRC samples was significantly higher than that in corresponding non-tumor samples. XIAP staining was positive in the cytoplasm of CRC cells. Higher XIAP protein expression was significantly correlated with tumor differentiation (P = 0.016), venous invasion (P = 0.039), and Duke's staging (P = 0.002). Moreover, XIAP-high group showed lower disease-free (P = 0.0136) and overall survival (P = 0.0084) rates than XIAP-low group. Multivariate analysis indicated that the status of XIAP expression was an independent prognostic factor for CRC (P = 0.0206; HR: 2.730; 95% CI: 1.226-5.445). CONCLUSION: The status of XIAP expression might become an independent prognostic marker for CRC.

Immunoexpression of inhibitors of apoptosis proteins and their antagonist SMAC/DIABLO in colorectal carcinoma: correlation with apoptotic index, cellular proliferation and prognosis.

The inhibitors of apoptosis proteins (IAPs) act by directly blocking cleaved caspase-3 (XIAP) or the protein SMAC/DIABLO, an antagonist. The inhibition of XIAP activity or the increase of SMAC activity might improve the therapeutic response of the patients. This work evaluated the immunoexpression of IAPs and SMAC in colorectal carcinoma and their correlation with apoptotic index (AI), cellular proliferation, p53 protein immunoexpression and patient survival rate. TMA paraffin blocks were made with colorectal cancer tissue and adjacent non-tumorous mucosa of 130 patients, not submitted to radio or chemotherapy. Sections of 4 microm were processed by immunohistochemistry for survivin, XIAP, cIAP-1, cIAP-2 and SMAC, and the immunoexpression scores were obtained. They were correlated between each other and with the AI obtained by anti-cleaved caspase-3 and M30 (cleaved cytokeratin-18) antibodies, the cellular proliferation index, p53 protein immunoexpression and patient survival data. Direct correlation occurred between the four IAPs studied in tumor and non-tumorous mucosa tissues. SMAC, survivin, cIAP-1 and cIAP-2 were positively correlated with tumoral tissue AI. Cellular proliferation and p53 immunoexpression was positively correlated with XIAP, SMAC and cIAP-1 scores. Low cIAP-1 immunoexpression showed a tendency for correlation with shorter patient survival. Equilibrium between the activities of IAPs and SMAC was demonstrated by the direct correlation between their immunoexpression. Correlation between SMAC and AI confirmed the pro-apoptotic activity of this protein. XIAP showed no inverse correlation with AI. XIAP, SMAC and cIAP-1 play a role in colorectal tumorigenesis, as demonstrated by their direct correlation with cellular proliferation and p53 protein. The tendency for correlation between low cIAP-1 immunoexpression and survival might indicate a role for this protein as a prognostic marker in colorectal cancer.

Isobaric tags for relative and absolute quantitation-based quantitative proteomic analysis of X-linked inhibitor of apoptosis and H2AX in etoposide-induced renal cell carcinoma apoptosis.

BACKGROUND: X-linked inhibitor of apoptosis (XIAP) is a vital factor in the anti-apoptosis mechanism of tumors and is highly expressed in renal cell carcinoma (RCC). However, the mechanism through which XIAP regulates DNA damage repair is unknown. This study investigated the regulatory mechanism of XIAP in etoposide-induced apoptosis in two Caki-1 cell lines with high or low XIAP expression. METHODS: The two cell lines were established using RNA interference technology. The differentially expressed proteins in the two cell lines were globally analyzed through an isobaric tags for relative and absolute quantitation-based quantitative proteomics approach. Proteomic analysis revealed 255, 375, 362, and 5 differentially expressed proteins after 0, 0.5, 3, and 12 h of drug stimulation, respectively, between the two cell lines. The identified differentially expressed proteins were involved in numerous biological processes. In addition, the expression of histone proteins (H1.4, H2AX, H3.1, H3.2, and H3.3) was drastically altered, and the effects of XIAP silencing were accompanied by the marked downregulation of H2AX. Protein-protein interactions were assessed and confirmed through immunofluorescence and Western blot analyses. RESULTS: The results suggested that XIAP may act as a vital cell signal regulator that regulates the expression of DNA repair-related proteins, such as H2AX, and influences the DNA repair process. CONCLUSIONS: Given these functions, XIAP may be the decisive factor in determining the sensitivity of RCC cell apoptosis induction in response to chemotherapeutic agents.

Inhibitor of apoptosis protein (IAP) profiling in experimental autoimmune encephalomyelitis (EAE) implicates increased XIAP in T lymphocytes.

In multiple sclerosis (MS) and its widely accepted animal model, experimental autoimmune encephalomyelitis (EAE), the failure of autoreactive immune cells to undergo apoptosis is thought to contribute to CNS tissue damage and disease progression. Promoting apoptosis of myelin-reactive immune cells in diseases such as MS, may delay disease progression and decrease the frequency and severity of relapses. X-linked inhibitor of apoptosis (XIAP) is a potent anti-apoptotic protein that inhibits intrinsic, extrinsic, and c-Jun amino-terminal kinase mediated apoptosis and was the only member of the inhibitor of apoptosis (IAP) family upregulated in whole blood from EAE mice. Similar increases in XIAP were also observed in both peripheral and encephalitogenic T lymphocytes. Increased XIAP expression in T cells within areas of demyelination in the CNS suggests that XIAP may be enhancing cell survival and thereby contributing to disease pathology.

Expression of inhibitors of apoptosis family protein in 7,12-dimethylbenz[a]anthracene-induced hamster buccal-pouch squamous-cell carcinogenesis is associated with mutant p53 accumulation and epigenetic changes.

Fifty outbred Syrian golden hamsters were equally divided into three experimental groups and two control groups. The pouches of the experimental groups were painted bilaterally with a 0.5% 7,12-dimethylbenz[a]anthracene (DMBA) solution thrice a week for 3, 7 and 14 weeks. One of the control groups was applied with mineral oil while another control group remained untreated throughout the experiment. Neither survivin nor cIAP2 could be detected in any of the control tissues, whereas survivin and cIAP2 were found to be significantly increased in 3-, 7- and 14-week DMBA-treated pouches compared with the control pouches. Expression of XIAP, cIAP1 and NAIP were noted for both the control and 3-, 7- and 14-week DMBA-treated pouches, but levels were found to be significantly elevated in the experimental groups compared with the control pouches. p53 was not detected in any control tissues, but was significantly increased in 3-, 7- and 14-week DMBA-treated pouches. Direct sequencing revealed a point mutation (C-->G) of p53 for pouch tissues treated with DMBA for 3 and 7 weeks, and there was a wide variation in the p53 sequence of the 14-week DMBA-treated pouch tissues, as compared with the control tissues. The control tissues had a survivin- and cIAP2-methylated allele, whereas the DMBA-treated tissues showed no evidence of survivin- and cIAP2-methylation. Neither the control nor DMBA-treated pouches showed evidence of XIAP-, cIAP1- or NAIP-methylation. Our results suggest that the expression of inhibitors of apoptosis family in DMBA-induced hamster buccal-pouch squamous-cell carcinogenesis may be modulated by both genetic (mutant p53) and epigenetic mechanisms.

Detection of cancer-related proteins in fresh-frozen ovarian cancer samples using laser capture microdissection.

Tumors are heterogeneous structures that contain different cell populations. Laser capture microdissection (LCM) can be used to obtain pure cancer cells from fresh-frozen cancer tissue and the surrounded environment, thus providing an accurate snapshot of the tumor and its microenvironment in vivo. We describe a new approach to isolate pure cancer cell population and evaluate protein expression. The process includes immunocytochemistry, laser microdissection, and western blot analysis. Using this technique, we can detect proteins such as X-linked inhibitor of apoptosis protein (XIAP) and Fas ligand (FasL) with as little as 1000 cells.

Immunohistochemical detection of XIAP in melanoma.

BACKGROUND: The X-linked inhibitor of apoptosis protein (XIAP) is the most potent of the inhibitor of apoptosis family of eight proteins. High levels of XIAP have been found in melanoma cell lines and are believed to play a role in therapeutic resistance in a number of malignancies. XIAP expression has not been investigated in clinically obtained melanoma tissue samples, nor have studies attempted to correlate XIAP expression with prognostic variables or clinical aggressiveness of melanomas. METHODS: Sixty-seven patients with primary cutaneous malignant melanoma for whom clinical follow up was available were identified from the records of the Mount Sinai Hospital, comprising 37 thin melanomas (Breslow thickness < 1.0 mm) and 30 thick melanomas (Breslow thickness > 1.0 mm). Archival paraffin sections from primary lesions and corresponding metastases were stained with monoclonal anti-XIAP antibody using routine immunohistochemical methods. RESULTS: Six benign intradermal nevi and four in situ melanomas were XIAP negative. 9 of 37 thin melanomas (24%) were XIAP positive. In contrast, 21 of 30 (73%) thick melanomas were XIAP positive, including 3 of 4 ulcerated melanomas that were strongly positive. Over a follow-up period ranging from 6 months to 6 years, 23 melanomas metastasized (22 thick, 1 thin). In total, XIAP was immunohistochemically detected in 17 of 23 metastases (74%). Metastasis occurred in 1 of 9 XIAP-positive thin melanomas; 0 of 28 XIAP-negative thin melanomas; 17 of 22 XIAP-positive thick melanomas, and 5 of 8 XIAP-negative thick melanomas (63%). CONCLUSIONS: XIAP is immunohistochemically detectable nearly three times more frequently in thick compared with thin melanomas. These results suggest that XIAP elevation may be correlated with increasing melanoma thickness and tumor progression.

DEBIO 1143, an IAP inhibitor, reverses carboplatin resistance in ovarian cancer cells and triggers apoptotic or necroptotic cell death.

The poor prognosis of ovarian cancer (it is the leading cause of death from gynecological cancers) is mainly due to the acquisition of resistance to carboplatin. Among the possible resistance pathways, resistance to apoptosis and especially the overexpression of inhibitor of apoptosis proteins (IAP) cIAP1 and X-linked IAP (XIAP), have been implicated. DEBIO 1143, a SMAC (second mitochondria-derived activator of caspase) mimetic, belongs to a new class of targeted agents currently being evaluated in clinical trials, which activate apoptotic cell death and block pro-survival signaling in cancer cells. Here, we demonstrate that DEBIO 1143 in vitro inhibits the cell viability of two carboplatin-sensitive cell lines (IGROV-1 and A2780S) as well as three carboplatin-resistant cell lines (A2780R, SKOV-3 and EFO-21). Of note, DEBIO 1143 is able to reverse resistance to carboplatin by inducing cell death either by apoptosis or necroptosis depending on the cell lines. To identify a biomarker able to predict the sensitivity of the cell lines to DEBIO 1143 treatment we analyzed the expression of the DEBIO 1143 targets cIAP1 and XIAP, and one of their downstream targets, caspase 9. These proteins did not constitute a marker of DEBIO 1143 sensitivity/resistance. Importantly, we confirmed these findings in vivo in SKOV-3 xenograft models where DEBIO 1143 highly potentiated carboplatin treatment.

Cell-specific expression of X-linked inhibitor of apoptosis in the anterior pituitary of streptozotocin-induced diabetic rats.

Cell death is increased in the anterior pituitary of poorly controlled diabetic rats, but anti-apoptotic mechanisms are also activated. We hypothesized that specific cell types are selectively protected against diabetes-induced cell death. To determine when anti-apoptotic mechanisms are activated, streptozotocin-induced diabetic rats were killed after 1, 4, 6 and 8 weeks of evolution. Anterior pituitaries were processed for western blot analysis to determine changes in the intrinsic cell death pathway and upstream kinases involved in cell protection mechanisms. An increase in cell death was detected by ELISA at 4 weeks of diabetes. TUNEL labelling demonstrated that this corresponded to death of primarily lactotrophs, a few somatotrophs, and no thyrotrophs, corticotrophs or gonadotrophs. Levels of phosphorylated (p) Akt were increased at 1 week of diabetes, while pERK1/2 levels increased at 4 weeks and pJNK at 6 weeks. Activation of caspase 3 decreased and anti-apoptotic members of the Bcl-2 protein family increased as early as 1 week after diabetes onset. These changes were coincident with increased IGF-I receptor levels. Levels of X-linked inhibitor of apoptosis protein (XIAP) increased significantly after 6 weeks of diabetes, as did activation of nuclear factor (NF)kappaB. Double immunohistochemistry indicated that XIAP was expressed in less than 1% of lactotrophs and gonadotrophs, approximately 50% of somatotrophs and more than 90% of corticotrophs and thyrotrophs. These results suggest that some cell survival mechanisms are rapidly activated in the anterior pituitary, even before increased cell death can be detected, while others are more delayed. Furthermore, both pituitary cell death and expression of protective mechanisms such as XIAP are cell-type specific.