Expression patterns of inhibitor of apoptosis proteins in malignant pleural mesothelioma

Exploring MicroRNA and Exosome Involvement in Malignant Pleural Mesothelioma Drug Response

Malignant pleural mesothelioma (MPM) is a deadly thoracic malignancy and existing treatment options are limited. Chemotherapy remains the most widely used first-line treatment regimen for patients with unresectable MPM, but is hampered by drug resistance issues. The current study demonstrated a modest enhancement of MPM cell sensitivity to chemotherapy drug treatment following microRNA (miRNA) transfection in MPM cell lines, albeit not for all tested miRNAs. This effect was more pronounced for FAK (PND-1186) small molecule inhibitor treatment; consistent with previously published data. We previously established that MPM response to survivin (YM155) small molecule inhibitor treatment is unrelated to basal survivin expression. Here, we showed that MPM response to YM155 treatment is enhanced following miRNA transfection of YM155-resistant MPM cells. We determined that YM155-resistant MPM cells secrete a higher level of exosomes in comparison to YM155-sensitive MPM cells. Despite this, an exosome inhibitor (GW4896) did not enhance MPM cell sensitivity to YM155. Additionally, our study showed no evidence of a correlation between the mRNA expression of inhibitor of apoptosis (IAP) gene family members and MPM cell sensitivity to YM155. However, two drug transporter genes, ABCA6 and ABCA10, were upregulated in the MPM cell lines and correlated with poor sensitivity to YM155.

Expression of phosphorylated ribosomal protein S6 in mesothelioma patients - correlation with clinico-pathological characteristics and outcome: results from the European Thoracic Oncology Platform (ETOP) Mesoscape project

Pleural mesothelioma (PM) is an aggressive malignancy with poor prognosis. Although histology and pathologic stage are important prognostic factors, better prognostic biomarkers are needed. The ribosomal protein S6 is a downstream target of the phosphatidylinositol 3-kinase (PI3K) pathway involved in protein synthesis and cell proliferation. In previous studies, low phosphorylated S6 (pS6) immunoreactivity was significantly correlated with longer progression-free survival (PFS) and overall survival (OS) in PM patients. We aimed to correlate pS6 expression to clinical data in a large multi-centre PM cohort as part of the European Thoracic Oncology Platform (ETOP) Mesoscape project. Tissue Micro Arrays (TMAs) of PM were constructed and expression of pS6 was evaluated by a semi-quantitatively aggregate H-score. Expression results were correlated to patient characteristics as well as OS/PFS. pS6 IHC results of 364 patients from 9 centres, diagnosed between 1999 and 2017 were available. The primary histology of included tumours was epithelioid (70.3%), followed by biphasic (24.2%) and sarcomatoid (5.5%). TMAs included both treatment-naïve and tumour tissue taken after induction chemotherapy. High pS6 expression (181 patients with H-score>1.41) was significantly associated with less complete resection. In the overall cohort, OS/PFS were not significantly different between pS6-low and pS6-high patients. In a subgroup analysis non-epithelioid (biphasic and sarcomatoid) patients with high pS6 expression showed a significantly shorter OS (p < 0.001, 10.7 versus 16.9 months) and PFS (p < 0.001, 6.2 versus 10.8 months). In subgroup analysis, in non-epithelioid PM patients high pS6 expression was associated with significantly shorter OS and PFS. These exploratory findings suggest a clinically relevant PI3K pathway activation in non-epithelioid PM which might lay the foundation for future targeted treatment strategies.

Circulating and local nuclear expression of survivin and fibulin-3 genes in discriminating benign from malignant respiratory diseases: correlation analysis

Survivin is an inhibitor of apoptosis as well as a promoter of cell proliferation. Fibulin-3 is a matrix glycoprotein that displays potential for tumor suppression or propagation. The present study aimed to validate the expression levels of survivin and fibulin-3 in benign and malignant respiratory diseases. This case-control study included 219 patients categorized into five groups. Group A included 63 patients with lung cancer, group B included 63 patients with various benign lung diseases, group D included 45 patients with malignant pleural mesothelioma (MPM), and group E included 48 patients with various benign pleural diseases. Group C included 60 healthy individuals (control group). Serum survivin and fibulin-3 levels were measured by ELISA, whereas their nuclear expressions in the lung and pleura were assessed via Western blot analysis. The results showed significantly higher survivin serum levels and significantly lower fibulin-3 levels in group A compared with in group B and controls (P<0.001). There were significantly higher serum levels of survivin and fibulin-3 in group D compared with in group E and controls (P<0.001), consistent with observed nuclear survivin and fibulin-3 expression levels. Fibulin-3 was determined to have higher value than survivin in discriminating lung cancer from MPM (P<0.05). Survivin and fibulin-3 could be useful diagnostic markers for lung and pleural cancers, and fibulin-3 expression was particularly useful in differentiating lung cancer from MPM.

Survivin expression as an independent predictor of overall survival in malignant peritoneal mesothelioma

Malignant peritoneal mesothelioma (MPeM) is an incurable cancer strongly associated with asbestos exposure and characterised by poor prognosis. The aim of the present study was to elucidate the prognostic and predictive value of CD146 and survivin expression in MPeM. Diagnostic biopsies from 60 patients with MPeM were collected and analysed for CD146, survivin and Ki-67 expression using immunohistochemistry. Complete clinical and follow-up information was obtained from patients' records. CD146 was expressed in 31/60 MPeM specimens and survivin in 34/60 specimens, with both expression levels being significantly associated with the Ki-67 labelling index (Ki-67LI). Kaplan-Meier and univariate Cox regression analyses revealed that a lower peritoneal cancer index (PCI), tumour-directed treatment, stage I, lower Ki-67LI and lower CD146 and survivin expression had a statistically positive effect on overall survival (OS). Cox regression analysis revealed that PCI [hazard ratio (HR)=1.99; 95% CI, 1.04–3.83; P=0.038], survivin (HR=1.47; 95% CI, 1.03–2.10; P=0.034) and treatment protocol including intraperitoneal chemotherapy (HR=0.28; 95% CI, 0.14–0.57; P=0.013) and systemic chemotherapy (HR=0.13; 95% CI, 0.04–0.42; P=0.013) retained independent prognostic significance for OS. All of these were included in the nomogram. Calibration curves showed good agreement between nomogram-predicted and observed survival. The C-index of the nomogram for predicting OS was 0.77. A lower PCI, intraperitoneal chemotherapy, systemic chemotherapy and a lower level of survivin were powerful prognostic markers in patients with MPeM. The proposed nomogram provides individual survival prediction for patients with MPeM.

High BIRC7 Expression Might Be an Independent Prognostic Indicator of Poor Recurrence-Free Survival in Patients With Prostate Cancer

Background:

BIRC7, which encodes Baculoviral inhibitor of apoptosis (IAP) repeat-containing protein 7, is an oncogene in multiple types of cancer. In this study, we examined the association between BIRC7 expression and the clinicopathological characteristics of prostate cancer, the independent prognostic value of BIRC7 in terms of recurrence-free survival, and the molecular mechanisms of its dysregulation.

Methods:

Data mining was performed using data from The Cancer Genome Atlas. The patients were divided into high and low BIRC7 expression groups according to the Youden index determined by receiver operating characteristic curves for recurrence. Subgroup analysis was performed according to T stages and Gleason score.

Results:

BIRC7 was significantly upregulated in prostate cancer tissues (N = 497) than in normal prostate tissues (N = 52). High BIRC7 expression group had lower ratios of overall response rate and medium-grade (Gleason score 6-7) tumors and higher proportions of nodal invasion and recurrence after surgery. Although Kaplan-Meier curves showed that high BIRC7 expression was generally associated with poor recurrence-free survival, the following subgroup analysis only confirmed the association in T3/T4 and medium-grade tumors. Multivariate analysis showed that BIRC7 expression was not an independent indicator of recurrence-free survival in T2 or high-grade tumors, but was independently associated with poor recurrence-free survival in T3/T4 tumors (hazard ratio: 4.249, 95% confidence interval: 1.563-11.546, P = .005) and in medium-grade tumors (hazard ratio: 6.041, 95% confidence interval: 1.763-20.703, P = .004). DNA amplification was associated with significantly upregulated BIRC7 expression. There was also a weak negative correlation between BIRC7 expression and its DNA methylation (Pearson r = −0.23).

Conclusion:

Based on these findings, we infer that BIRC7 upregulation might serve as a valuable biomarker of increased recurrence risk in advanced T stages and medium-grade prostate cancer. Its expression is at least regulated by both copy number alteration and DNA methylation.

Hairpin-Hairpin Molecular Beacon Interactions for Detection of Survivin mRNA in Malignant SW480 Cells

Cancer biomarkers offer unique prospects for the development of cancer diagnostics and therapy. One of such biomarkers, protein survivin (Sur), exhibits strong antiapoptotic and proliferation-enhancing properties and is heavily expressed in multiple cancers. Thus, it can be utilized to provide new modalities for modulating the cell-growth rate, essential for effective cancer treatment. Herein, we have focused on the development of a new survivin-based cancer detection platform for colorectal cancer cells SW480 using a turn-on fluorescence oligonucleotide molecular beacon (MB) probe, encoded to recognize Sur messenger RNA (mRNA). Contrary to the expectations, we have found that both the complementary target oligonucleotide strands as well as the single- and double-mismatch targets, instead of exhibiting the anticipated simple random conformations, preferentially formed secondary structure motifs by folding into small-loop hairpin structures. Such a conformation may interfere with, or even undermine, the biorecognition process. To gain better understanding of the interactions involved, we have replaced the classical Tyagi-Kramer model of interactions between a straight target oligonucleotide strand and a hairpin MB with a new model to account for the hairpin-hairpin interactions as the biorecognition principle. A detailed mechanism of these interactions has been proposed. Furthermore, in experimental work, we have demonstrated an efficient transfection of malignant SW480 cells with SurMB probes containing a fluorophore Joe (SurMB-Joe) using liposomal nanocarriers. The green emission from SurMB-Joe in transfected cancer cells, due to the hybridization of the SurMB-Joe loop with Sur mRNA hairpin target, corroborates Sur overexpression. On the other hand, healthy human-colon epithelial cells CCD 841 CoN show only negligible expression of survivin mRNA. These experiments provide the proof-of-concept for distinguishing between the cancer and normal cells by the proposed hairpin-hairpin interaction method. The single nucleotide polymorphism sensitivity and a low detection limit of 26 nM (S/N = 3σ) for complementary targets have been achieved.

Livin/BIRC7 expression as malignancy marker in adrenocortical tumors

Livin/BIRC7 is a member of the inhibitors of apoptosis proteins family, which are involved in tumor development through the inhibition of caspases. Aim was to investigate the expression of livin and other members of its pathway in adrenocortical tumors and in the adrenocortical carcinoma (ACC) cell line NCI-H295R.

The mRNA expression of livin, its isoforms α and β, XIAP, CASP3 and DIABLO was evaluated by qRT-PCR in 82 fresh-frozen adrenal tissues (34 ACC, 25 adenomas = ACA, 23 normal adrenal glands = NAG). Livin protein expression was assessed by immunohistochemistry in 270 paraffin-embedded tissues (192 ACC, 58 ACA, 20 NAG). Livin, CASP3 and cleaved caspase-3 were evaluated in NCI-H295R after induction of livin overexpression.

Relative livin mRNA expression was significantly higher in ACC than in ACA and NAG (0.060 ± 0.116 vs 0.004 ± 0.014 and 0.002 ± 0.009, respectively, p < 0.01), being consistently higher in tumors than in adjacent NAG and isoform β more expressed than α. No significant differences in CASP3, XIAP and DIABLO levels were found among these groups. In immunohistochemistry, livin was localized in both cytoplasm and nuclei. The ratio between cytoplasmic and nuclear staining was significantly higher in ACC (1.51 ± 0.66) than in ACA (0.80 ± 0.35) and NAG (0.88 ± 0.27; p < 0.0001). No significant correlations were observed between livin expression and histopathological parameters or clinical outcome. In NCI-H295R cells, the livin overexpression slightly reduced the activation of CASP3, but did not correlate with cell viability.

In conclusion, livin is specifically over-expressed in ACC, suggesting that it might be involved in adrenocortical tumorigenesis and represent a new molecular marker of malignancy.

Heterogeneous Contributing Factors in MPM Disease Development and Progression: Biological Advances and Clinical Implications

Malignant pleural mesothelioma (MPM) tumors are remarkably aggressive and most patients only survive for 5–12 months; irrespective of stage; after primary symptoms appear. Compounding matters is that MPM remains unresponsive to conventional standards of care; including radiation and chemotherapy. Currently; instead of relying on molecular signatures and histological typing; MPM treatment options are guided by clinical stage and patient characteristics because the mechanism of carcinogenesis has not been fully elucidated; although about 80% of cases can be linked to asbestos exposure. Several molecular pathways have been implicated in the MPM tumor microenvironment; such as angiogenesis; apoptosis; cell-cycle regulation and several growth factor-related pathways predicted to be amenable to therapeutic intervention. Furthermore, the availability of genomic data has improved our understanding of the pathobiology of MPM. The MPM genomic landscape is dominated by inactivating mutations in several tumor suppressor genes; such as CDKN2A; BAP1 and NF2. Given the complex heterogeneity of the tumor microenvironment in MPM; a better understanding of the interplay between stromal; endothelial and immune cells at the molecular level is required; to chaperone the development of improved personalized therapeutics. Many recent advances at the molecular level have been reported and several exciting new treatment options are under investigation. Here; we review the challenges and the most up-to-date biological advances in MPM pertaining to the molecular pathways implicated; progress at the genomic level; immunological progression of this fatal disease; and its link with developmental cell pathways; with an emphasis on prognostic and therapeutic treatment strategies.

MicroRNA-212 inhibits the proliferation, migration and invasion of renal cell carcinoma by targeting X-linked inhibitor of apoptosis protein (XIAP)

MicroRNAs have been found to be critical regulator of cancer cell biology. MicroRNA-212 (miR-212) was identified to be a critical cancer-associated microRNA playing either oncogenic functions or tumor suppressive roles in different types of human cancers. In this study, we found that the level of miR-212 in renal cell carcinoma (RCC) tissues was significantly lower than that in adjacent non-tumor tissues. Decreased level of miR-212 was associated with advanced T stage and TNM stage of RCC. The expression of miR-212 was decreased in RCC cell lines as compared with the HK-2 cell line. Overexpression of miR-212 inhibited cell viability, proliferation, migration and invasion of CAKI-2 cells. Knockdown of miR-212 increased cell viability and proliferation, migration and invasion of ACHN cells. In vivo experiments showed that miR-212 inhibited the proliferation and promoted the apoptosis of ACHN cells in nude mice and thus inhibited the in vivo tumor growth of CAKI-2 cells. Furthermore, we confirmed that X-linked inhibitor of apoptosis protein (XIAP) was the downstream target of miR-212. The expression level of miR-212 was negatively correlated with XIAP expression in RCC tissues. Moreover, XIAP mediated the tumor suppressive roles of miR-212 in RCC. Finally, we demonstrated that the aberrant expression of miR-212 and XIAP was evidently correlated with poor prognosis of RCC patients. In all, miR-212 can act as a prognostic biomarker for RCC patients and inhibits the growth and metastasis of RCC cells by inhibiting XIAP.

Regulation of microRNA using promising dietary phytochemicals: Possible preventive and treatment option of malignant mesothelioma

Malignant mesothelioma (MM) is a very aggressive, lethal cancer, and its incidence is increasing worldwide. Development of multi-drug resistance, therapy related side-effects, and disease recurrence after therapy are the major problems for the successful treatment of MM. Emerging evidence indicates that dietary phytochemicals can exert anti-cancer activities by regulating microRNA expression. Until now, only one dietary phytochemical (ursolic acid) has been reported to have MM microRNA regulatory ability. A large number of dietary phytochemicals still remain to be tested. In this paper, we have introduced some dietary phytochemicals (curcumin, epigallocatechin gallate, quercetin, genistein, pterostilbene, resveratrol, capsaicin, ellagic acid, benzyl isothiocyanate, phenethyl isothiocyanate, sulforaphane, indole-3-carbinol, 3,3'-diindolylmethane, diallyl disulphide, betulinic acid, and oleanolic acid) which have shown microRNA regulatory activities in various cancers and could regulate MM microRNAs. In addition to microRNA regulatory activities, curcumin, epigallocatechin gallate, quercetin, genistein, resveratrol, phenethyl isothiocyanate, and sulforaphane have anti-mesothelioma potentials, and pterostilbene, capsaicin, ellagic acid, benzyl isothiocyanate, indole-3-carbinol, 3,3'-diindolylmethane, diallyl disulphide, betulinic acid, and oleanolic acid have potentials to inhibit cancer by regulating the expression of various genes which are also known to be aberrant in MM.

Cisplatin and resveratrol induce apoptosis and autophagy following oxidative stress in malignant mesothelioma cells

Malignant mesothelioma (MM) is characterized by poor responsiveness to current chemotherapeutic drugs, usually owing to high resistance to apoptosis. Here, we investigated chemosensitizing effects of phytochemical resveratrol, in combination with cisplatin, on MM cells. The combination treatment of cisplatin and resveratrol (CDDP/RSV) synergistically induced apoptosis, as evidenced by typical cell morphological changes, the appearance of sub-G0/G1 peak, an increase in the Annexin V(+) cells and the cleavage of caspase-3 and PARP. CDDP/RSV increased ROS production and depolarization of mitochondrial membrane potential with an increase in the Bax/Bcl-2 ratio. These changes were attenuated by pretreatment with N-acetylcysteine, suggesting that CDDP/RSV induced apoptosis through oxidative mitochondrial damage. Compared with MSTO-211H cells, CDDP/RSV was less efficient in killing H-2452 cells. H-2452 cells exhibited an enhanced autophagy to CDDP/RSV, as observed by an increase in viable cells exhibiting intense LysoTracker Red staining and up-regulation of Beclin-1 and LC3A. Inhibition of autophagy by bafilomycin A1 rendered cells more sensitive to CDDP/RSV-induced cytotoxicity and this was associated with induction of apoptosis. These data indicate that the increased resistance of H-2452 cells to CDDP/RSV is closely related to the activation of self-defensive autophagy, and provide the rationale for targeting the autophagy regulation in the treatment of MM.

Serum Survivin Levels and Outcome of Chemotherapy in Patients with Malignant Mesothelioma

BACKGROUND

Survivin is an inhibitor of apoptosis protein involved in the regulation of cell proliferation that could be used as a marker for cancer diagnosis or prognosis. Our aim was to evaluate whether serum survivin levels influence the outcome of cisplatin-based chemotherapy in patients with malignant mesothelioma (MM).

METHODS

Serum survivin levels were determined using human survivin enzyme-linked immunosorbent assay in 78 MM patients before chemotherapy, after chemotherapy, and at disease progression. The influence on tumor response and survival was evaluated using nonparametric tests and Cox regression.

RESULTS

A median serum survivin level at diagnosis was 4.1 (0-217.5) pg/mL. Patients with a progressive disease had significantly higher survivin levels before chemotherapy (p = 0.041). A median serum survivin level after chemotherapy was 73.1 (0-346.2) pg/mL. If survivin levels increased after chemotherapy, patients had, conversely, better response (p = 0.001, OR = 5.40, 95% CI = 1.98-14.72). Unexpectedly, patients with increased survivin levels after chemotherapy also had longer progression-free (p < 0.001, HR = 0.33, 95% CI = 0.20-0.57) and overall survival (p = 0.001, HR = 0.29, 95% CI = 0.14-0.58).

CONCLUSIONS

These results suggest that serum survivin levels before and during chemotherapy could serve as a biomarker predicting MM treatment response.

Relationship between expression of Livin and the biological behavior of human oral squamous cell carcinoma

Livin is one of the most important members of the inhibitor protein (IAP) family. It is overexpressed in several types of tumors and may have prognostic significance. The purpose of this study was to investigate Livin expression in human oral squamous cell carcinomas (OSCCs) and to determine whether Livin affects tumor cell behavior in OSCC cell lines and thus evaluate its potential usefulness in serving as a possible target for molecular-targeted therapy in a preclinical model. The expression of Livin protein was investigated in human OSCC tissues through immunohistochemistry and western blot analysis. To evaluate the impact of Livin knockdown on the behavior of human OSCC cell lines, invasion, migration, proliferation and apoptosis assays using small-interfering RNA (siRNA) were performed. RT-PCR and western blot analysis were used to assess alteration of Livin expression at the mRNA and protein levels. The results revealed that expression of Livin was increased in the human OSCC tissues compared with the adjacent normal mucosa. In addition, immunoreactivity of Livin was expressed in 8 OSCC tissues (44.4%). Knockdown of Livin resulted in significantly reduced cell invasion, migration and proliferation in the human OSCC cells. Livin knockdown induced cell apoptosis in the human OSCC cells. Moreover, Livin inhibited apoptosis by suppressing the activity of caspases in the human OSCC cells. In conclusion, livin is associated with invasive and oncogenic phenotypes such as tumor cell invasion, tumor cell migration, tumor cell proliferation, and resistance to apoptosis in human OSCC cells.

Pharmacological targeting of p53 through RITA is an effective antitumoral strategy for malignant pleural mesothelioma

Malignant mesothelioma, a very aggressive tumor associated to asbestos exposure, is expected to increase in incidence, and unfortunately, no curative modality exists. Reactivation of p53 is a new attractive antitumoral strategy. p53 is rarely mutated in mesothelioma, but it is inactivated in most tumors by the lack of p14(ARF). Here, we evaluated the feasibility of this approach in pleural mesothelioma by testing RITA and nutlin-3, two molecules able to restore p53 function through a different mechanism, on a panel of mesothelioma cell lines representing the epithelioid (NCI-H28, NCI-H2452, IST-MES 2), biphasic (MSTO-211H), and sarcomatoid (NCI-H2052) histotypes compared with the normal mesothelial HMC-hTERT. RITA triggered robust caspase-dependent apoptosis specifically in epithelioid and biphasic mesothelioma cell lines, both through wild-type and mutant p53, concomitant to p21 downregulation. Conversely, nutlin-3 induced a p21-dependent growth arrest, rather than apoptosis, and was slightly toxic on HMC-hTERT.   Interestingly, we identified a previously undetected point mutation of p53 (p.Arg249Ser) in IST-MES 2, and showed that RITA is also able to reactivate this p53 mutant protein and its apoptotic function. RITA reduced tumor growth in a MSTO-211H-derived xenograft model of mesothelioma and synergized with cisplatin, which is the mainstay of treatment for this tumor. Our data indicate that reactivation of p53 and concomitant p21 downregulation effectively induce cell death in mesothelioma, a tumor characterized by a high intrinsic resistance to apoptosis. Altogether, our findings provide the preclinical framework supporting the use of p53-reactivating agents alone, or in combination regimens, to improve the outcome of patients with mesothelioma.

Expression and clinical significance of livin protein in hepatocellular carcinoma

In this study, the two-step PV method of immunohistochemistry was used to determine livin protein expression in HCC tissues, pericarcinoma tissues, hepatitis/hepatic cirrhosis tissues, and normal hepatic tissues, and livin protein expression was detected in the blood plasma of patients with HCC before and after surgery, subjects with hepatic cirrhosis and hepatitis, and healthy blood donors using ELISA. Livin protein expression was significantly higher in HCC tissues than that in normal hepatic tissues and hepatitis/hepatic cirrhosis tissues, with no significant difference between HCC tissues and pericarcinoma tissues. The HCC patients with positive livin protein expression had a significantly higher survival rate than those with negative livin protein expression. Livin protein expression was significantly higher in the blood plasma of patients with HCC before and after surgery and in patients with hepatic cirrhosis and hepatitis than that in healthy blood donors, whereas livin protein expression in the blood plasma of patients with HCC was not significantly different from that of patients with hepatic cirrhosis and hepatitis. Livin protein expression in HCC tissues did not correlate with that in the blood plasma of the same HCC patients. Livin protein expression may be a potential, effective indicator for assessing prognosis in patients with HCC.

SAHA overcomes FLIP-mediated inhibition of SMAC mimetic-induced apoptosis in mesothelioma

Malignant pleural mesothelioma (MPM) is a highly pro-inflammatory malignancy that is rapidly fatal and increasing in incidence. Cytokine signaling within the pro-inflammatory tumor microenvironment makes a critical contribution to the development of MPM and its resistance to conventional chemotherapy approaches. SMAC mimetic compounds (SMCs) are a promising class of anticancer drug that are dependent on tumor necrosis factor alpha (TNFα) signaling for their activity. As circulating TNFα expression is significantly elevated in MPM patients, we examined the sensitivity of MPM cell line models to SMCs. Surprisingly, all MPM cell lines assessed were highly resistant to SMCs either alone or when incubated in the presence of clinically relevant levels of TNFα. Further analyses revealed that MPM cells were sensitized to SMC-induced apoptosis by siRNA-mediated downregulation of the caspase 8 inhibitor FLIP, an antiapoptotic protein overexpressed in several cancer types including MPM. We have previously reported that FLIP expression is potently downregulated in MPM cells in response to the histone deacetylase inhibitor (HDACi) Vorinostat (SAHA). In this study, we demonstrate that SAHA sensitizes MPM cells to SMCs in a manner dependent on its ability to downregulate FLIP. Although treatment with SMC in the presence of TNFα promoted interaction between caspase 8 and the necrosis-promoting RIPK1, the cell death induced by combined treatment with SAHA and SMC was apoptotic and mediated by caspase 8. These results indicate that FLIP is a major inhibitor of SMC-mediated apoptosis in MPM, but that this inhibition can be overcome by the HDACi SAHA.

Overexpression of Numb suppresses tumor cell growth and enhances sensitivity to cisplatin in epithelioid malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a highly aggressive and conventional treatment-resistant tumor with a dismal prognosis. Among the three histological subtypes of MPM, the epithelioid is the most common type. Numb is considered as a tumor suppressor playing a critical role in controlling asymmetric cell division, maintenance of stem cell compartments, ubiquitination of specific substrates and regulating Notch-, Hedgehog- and TP53-activated pathways. The present study was designed to analyze the role of Numb in epithelioid MPM. We investigated the expression of Numb in 39 epithelioid MPM and 22 normal pleural tissues by immunohistochemistry. Furthermore, we overexpressed Numb in NCI-H2452, an epithelioid human MPM cell line, and investigated the effect of Numb overexpression on the proliferation, apoptosis and sensitivity to cisplatin in cells. The expression of Numb was significantly lower in MPM compared to the control group and Numb had an inverse correlation with the ki-67 labeling index. Loss of Numb expression was associated with poor prognosis in epithelioid MPM. Overexpression of Numb in NCI-H2452 cells significantly inhibited proliferation, promoted apoptosis and enhanced sensitivity to cisplatin. Moreover, Numb overexpression activated caspase-9 and caspase-3 through release of cytochrome c as well as downregulation of XIAP and survivin. We speculate that cytochrome c/caspase signaling is a possible mechanism through which Numb enhances the apoptosis of NCI-H2452 cells. These results suggest that Numb may be involved in epithelioid MPM development, and its upregulation may confer sensitivity to cisplatin, suggesting potential therapeutic options for MPM.

Clinical and biologic prognostic factors in malignant pleural mesothelioma

Malignant pleural mesothelioma is an extremely aggressive neoplasm of the pleura mainly attributable to asbestos exposure. Conventional medical, physical, and surgical treatments and their combinations are basically ineffective and just a few subjects experience some benefit. No definite guidelines can be provided in patient selection and therapeutic strategies. Currently, malignant pleural mesothelioma therapy is guided by clinical stage and patient characteristics, which are quite unreliable, rather than by the histological or molecular features of the tumor. In the present review the impact on prognosis of classic (i.e. etiology, age, gender, histology, staging), as well as relatively new clinical factors such as quality of life, positron emission tomography assessment, and occult residual disease, are firstly evaluated. In the second section of the review several biological variables and genetic markers, which have been recently recognized as the bases of the disease onset and development, are listed and discussed. There are serum and tissue markers. The latter are mainly related to cell cycle regulation, apoptosis, and growth factor pathways. These novel factors may play an important role in defining the prognosis of the disease and, subsequently, may have a place in addressing therapy.

Livin expression may be regulated by miR-198 in human prostate cancer cell lines

Livin has been recently described as an inhibitor of apoptosis, which is established to be associated with a variety of cancers. Metastatic prostate cancer cell line DU145 expresses high level of Livin mRNA yet low level of its protein. Thus, we hypothesised that Livin was regulated by some miRNAs in prostate cancer cells. Livin mRNA and protein expression were investigated by reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot, respectively. Hairpin RT-PCR was performed to analyse suspected miRNAs. Livin 3'-untranslated region (3'-UTR) wild type and mutant dual-luciferase reporter vectors were constructed. The miRNAs targeting Livin were predicted by the online software - TargetScan and miRBase, and then validated by dual luciferase reporter gene assay. We found that post-transcriptional inhibition of Livin occurred in DU145 cells, assumedly due to the miRNA pathway. Among 6 candidate miRNAs, miR-198 expression was identified to be negatively correlated with Livin expression level in some prostate cancer cell lines. Further study revealed miR-198-mediated repression of Livin expression. Therefore, the regulation of Livin expression may involve miR-198 in prostate cancer cell lines.

Molecular resistance fingerprint of pemetrexed and platinum in a long-term survivor of mesothelioma

Background

Pemetrexed, a multi-folate inhibitor combined with a platinum compound is the first-line treatment of malignant mesothelioma, but median survival is still one year. Intrinsic and acquired resistance to pemetrexed is common, but its biological basis is obscure. Here we report for the first time a genome-wide profile of acquired resistance in the tumour from an exceptional case with advanced pleural mesothelioma and almost six years survival after 39 cycles of second-line pemetrexed/carboplatin treatment.

Methodology and Principal Findings

Genome-wide analysis with Illumina BeadChip Kit of 25,000 genes was performed on mRNA from pre-treatment and post-resistance biopsies from this individual as well on case and control samples from our previously published study (in total 17 samples). Cell specific expression of proteins encoded by selected genes were analysed by immunohistochemistry. Serial serum levels of CA125, CYFRA21-1 and SMRP levels were examined. TS protein, the main target of pemetrexed was overexpressed. Proteins and genes related to DNA damage response, elongation and telomere extension and repair related directly and indirectly to platinum resistance were overexpressed, as the CHK1 protein and the genes CHEK2, LIG3, POLD1, POLA2, FANCD2, PRPF19, RECQ5 respectively, the last two not previously described in mesothelioma. We observed a down-regulation of leukocyte transendothelial migration and cell adhesion molecules pathways. Silencing of NT5C in two mesothelioma cell lines did not sensitize the cells to Pemetrexed. Proposed resistance markers are TS, KRT7/ CK7, TYMP/ thymidine phosphorylase and down-regulated SPARCL1 and CDKN1B. Moreover, comparison of the primary expression of the sensitive versus a primary resistant case showed multi-fold overexpressed DNA repair, cell cycle, cytokinesis, and spindle formation in the latter. Serum CA125 and SMRP reflected the clinical and radiological course and tumour burden.

Conclusions

Genome-wide microarray of mesothelioma pre- and post-resistance biopsies indicated a novel resistance signature to pemetrexed/carboplatin that deserve validation in a larger cohort.

The clinical effect of the inhibitor of apopotosis protein livin in melanoma

OBJECTIVE

The inhibitor of apoptosis protein (IAP) livin is frequently overexpressed in melanoma. Livin binds caspases and thereby inhibits apoptosis. We found that caspases cleave livin to produce a truncated form with a paradoxical proapoptotic activity.

METHODS

We assessed the correlation of livin expression with survival among 114 melanoma patients treated with an autologous melanoma vaccine. In 52 patients, resection resulted in no evidence of disease (NED) and 62 remained with active disease (WAD). Protein levels were assessed using Western blot.

RESULTS

We found livin protein expression in 44/114 samples (38.4%). Median overall survival was 1.4 years in NED patients with high levels of livin protein, 8.4 years in those with low-intermediate levels and not reached in patients who did not express livin (p = 0.025). The corresponding overall survival was 2.3 years among WAD patients with high levels of livin protein, 11.3 years in those with low-intermediate levels and, paradoxically, only 4.0 years in patients who did not express livin (p = 0.012).

CONCLUSION

Livin protein expression may play a role in the progression of melanoma and correlates with survival. A high level of the protein is associated with a poor prognosis. However, in WAD patients low to intermediate level of livin, rather than absence of the protein, is associated with a favorable prognosis. This is probably due to the paradoxical proapoptotic activity of this important regulator of apoptosis.

BIRC5 promoter SNPs do not affect nuclear survivin expression and survival of malignant pleural mesothelioma patients

PURPOSE

Malignant pleural mesothelioma is an incurable, asbestos-associated cancer. Its incidence is rapidly increasing and survival remains short. Apoptosis deregulation is an important feature of cancer and survivin, a member of the inhibitor-of-apoptosis-protein family encoded by the BIRC5 gene, has been suggested to have a role in the development and progression of several cancers. Genetic variability, in particular single nucleotide polymorphisms in the BIRC5 promoter, may affect the protein's expression levels. The aim of our study was to elucidate the effects of BIRC5 promoter single nucleotide polymorphisms on survivin expression, patient survival and age at diagnosis in malignant pleural mesothelioma.

METHODS

Archival mesothelioma samples from 101 Slovenian patients were immunohistochemically analysed for survivin expression. DNA was extracted from tumour samples and genotyped for three BIRC5 promoter single nucleotide polymorphisms (-31G > C, -241C > T and -625G > C). Genotypes were associated with nuclear survivin expression. Nuclear survivin expression, genotypes, haplotypes, histological type, gender and asbestos exposure were included in univariate Cox survival analyses.

RESULTS

Survivin expression was detected in both tumour cell nuclei and cytoplasms in all analysed samples. No association between BIRC5 promoter polymorphism genotypes or haplotypes and nuclear survivin expression was found. Polymorphism -241C > T affected patients' age at diagnosis. Survival analysis confirmed that younger age at diagnosis and epitheloid histological type improved survival, but no significant effects of nuclear survivin expression or genotype/haplotype on overall survival were observed.

CONCLUSION

Our findings indicate no relationship between BIRC5 genotypes and survivin expression or overall survival in mesothelioma patients. We observed that BIRC5 -241C > T polymorphism had a significant effect on patient age at diagnosis.

Validation of tissue microarray technology in malignant pleural mesothelioma

AIMS

Tissue microarray (TMA) technology has been utilised for assessment of cancers including malignant pleural mesothelioma (MPM). Given the intralesional heterogeneity of MPM, it is questionable if TMAs can adequately represent MPMs. We here investigate the validity of TMAs for MPM.

METHODS

TMAs were constructed from at least five cores for each of 80 archival tumours processed by two centres between 1994 and 2009. The percentage of cases correctly subtyped on TMAs compared with whole sections, in relation to the number of cores analysed, was calculated. Immunohistochemical labelling for calretinin and D2-40 was performed on TMAs and whole sections. To evaluate the validity of quantitative immunohistochemistry, percentages of positive cells were recorded and two-way analysis of variance (ANOVA) performed.

RESULTS

Five cores were assessable for 91% of patients. Four cores were sufficient to reach concordance with the whole-section result in 98% of cases for calretinin and 99% for D2-40. The correlation of the quantitative scores between the whole section and TMA cores was statistically significant (D2-40, rho = 0.84, p < 2.2e-16; calretinin, rho = 0.65, p = 7.9e-11). Neither the origin nor age of the blocks affected the results.

CONCLUSION

If a minimum of four cores is used, TMA is an appropriate method for immunohistochemistry in MPM.

c-IAP1 expression and tumor chemosensitivity in esophageal squamous cell carcinoma

AIM: To investigate the expression of cellular inhibitor of apoptosis protein 1 (c-IAP1) in esophageal squamous cell carcinoma (ESCC) and to evaluate the correlation between c-IAP1 expression and chemosensitivity of ESCC cell lines.

METHODS: Immunohistochemistry staining was performed to determine the expression of c-IAP1 in ESCC on tissue microarray. The chi-square test was used to analyze the correlation between c-IAP1 expression and clinicopathologic parameters of ESCC. The expression of c-IAP1 and Smac in several ESCC cell lines was detected by Western blot. The chemosensitivity of ESCC cell lines was evaluated by RNA interference with Smac gene expression and MTT assay.

RESULTS: c-IAP1 expression was found in 67% (35/52) of ESCC tissue specimens and in 54% (28/52) of tumor-adjacent normal tissue specimens. c-IAP1 expression was not correlated with age, gender, tumor stage (all P > 0.05). c-IAP1 was localized to both the cytoplasm and nucleus. Cytoplasmic c-IAP1 expression was detected more frequently in ESCC than in tumor-adjacent tissue specimens [45% (24/52) vs 4% (2/52), P < 0.001]. c-IAP1 and Smac were widely expressed in ESCC cell lines, including EC0156, KYSE510, KYSE180, KYSE170, and KYSE30. Knockdown of Smac significantly reduced chemosensitivity of KYSE170 cell line to anticancer drugs.

CONCLUSION: The expression of c-IAP1 was up-regulated in both ESCC cell lines and tumor tissue. Smac mediates the degradation of c-IAP1 after cisplatin treatment. c-IAP1 and Smac might regulate chemosensitivity of ESCC cell lines.

X-linked inhibitor of apoptosis protein (XIAP) mediates cancer cell motility via Rho GDP dissociation inhibitor (RhoGDI)-dependent regulation of the cytoskeleton

X-linked inhibitor of apoptosis protein (XIAP) overexpression has been found to be associated with malignant cancer progression and aggression in individuals with many types of cancers. However, the molecular basis of XIAP in the regulation of cancer cell biological behavior remains largely unknown. In this study, we found that a deficiency of XIAP expression in human cancer cells by either knock-out or knockdown leads to a marked reduction in β-actin polymerization and cytoskeleton formation. Consistently, cell migration and invasion were also decreased in XIAP-deficient cells compared with parental wild-type cells. Subsequent studies demonstrated that the regulation of cell motility by XIAP depends on its interaction with the Rho GDP dissociation inhibitor (RhoGDI) via the XIAP RING domain. Furthermore, XIAP was found to negatively regulate RhoGDI SUMOylation, which might affect its activity in controlling cell motility. Collectively, our studies provide novel insights into the molecular mechanisms by which XIAP regulates cancer invasion and offer a further theoretical basis for setting XIAP as a potential prognostic marker and specific target for treatment of cancers with metastatic properties.

Advances in the biology of malignant pleural mesothelioma

Malignant pleural mesothelioma is a highly aggressive cancer with a very poor prognosis. Although the mechanism of carcinogenesis is not fully understood, approximately 80% of malignant pleural mesothelioma can be attributed to asbestos fiber exposure. This disease is largely unresponsive to conventional chemotherapy or radiotherapy, and most patients die within 10-17 months of their first symptoms. Currently, malignant pleural mesothelioma therapy is guided by clinical stage and patient characteristics rather than by the histological or molecular features of the tumor. Several molecular pathways involved in malignant pleural mesothelioma have been identified; these include cell cycle regulation, apoptosis, growth factor pathways, and angiogenesis. Unfortunately, several agents targeting these processes, including erlotinib, gefitinib, and imatinib, have proven ineffective in clinical trials. A greater understanding of the molecular pathways involved in malignant pleural mesothelioma is needed to develop better diagnostics, therapeutics, and preventative measures. Moreover, understanding the biological basis of mesothelioma progression may facilitate personalized treatment approaches, and early identification of poor prognostic indicators may help reduce the heterogeneity of the clinical response. This paper reviews advances in the molecular biology of malignant pleural mesothelioma in terms of pathogenesis, the major molecular pathways and the associated therapeutic strategies, and the roles of biomarkers.

Biomarkers for early detection of malignant mesothelioma: diagnostic and therapeutic application

Malignant mesothelioma (MM) is a rare and aggressive tumour of the serosal cavities linked to asbestos exposure. Improved detection methods for diagnosing this type of neoplastic disease are essential for an early and reliable diagnosis and treatment. Thus, focus has been placed on finding tumour markers for the non-invasive detection of MM. Recently, some blood biomarkers have been described as potential indicators of early and advanced MM cancers. The identification of tumour biomarkers alone or in combination could greatly facilitate the surveillance procedure for cohorts of subjects exposed to asbestos, a common phenomenon in several areas of western countries.

Phenotype-dependent apoptosis signalling in mesothelioma cells after selenite exposure

Background

Selenite is a promising anticancer agent which has been shown to induce apoptosis in malignant mesothelioma cells in a phenotype-dependent manner, where cells of the chemoresistant sarcomatoid phenotype are more sensitive.

Methods

In this paper, we investigate the apoptosis signalling mechanisms in sarcomatoid and epithelioid mesothelioma cells after selenite treatment. Apoptosis was measured with the Annexin-PI assay. The mitochondrial membrane potential, the expression of Bax, Bcl-XL, and the activation of caspase-3 were assayed with flow cytometry and a cytokeratin 18 cleavage assay. Signalling through JNK, p38, p53, and cathepsins B, D, and E was investigated with chemical inhibitors. Furthermore, the expression, nuclear translocation and DNA-binding activity of p53 was investigated using ICC, EMSA and the monitoring of p21 expression as a downstream event. Levels of thioredoxin (Trx) were measured by ELISA.

Results

In both cell lines, 10 μM selenite caused apoptosis and a marked loss of mitochondrial membrane potential. Bax was up-regulated only in the sarcomatoid cell line, while the epithelioid cell line down-regulated Bcl-XL and showed greater caspase-3 activation. Nuclear translocation of p53 was seen in both cell lines, but very little p21 expression was induced. Chemical inhibition of p53 did not protect the cells from apoptosis. p53 lost its DNA binding ability after selenite treatment and was enriched in an inactive form. Levels of thioredoxin decreased after selenite treatment. Chemical inhibition of MAP kinases and cathepsins showed that p38 and cathepsin B had some mediatory effect while JNK had an anti-apoptotic role.

Conclusion

We delineate pathways of apoptosis signalling in response to selenite, showing differences between epithelioid and sarcomatoid mesothelioma cells. These differences may partly explain why sarcomatoid cells are more sensitive to selenite.

New diagnostic and molecular characteristics of malignant mesothelioma

Malignant mesothelioma is a primary cancer of the serosal cavities, an anatomic site that is also frequently affected by metastatic disease, predominantly from primary carcinomas of the lung, breast, and ovary. Advances in immunohistochemistry have resulted in improved diagnostic sensitivity and specificity in the differential diagnosis between metastatic adenocarcinoma and malignant mesothelioma in both cytological and histological material. Recently, the author's group applied high throughput technology to the identification of new markers that may aid in differentiating malignant mesothelioma from ovarian and peritoneal serous carcinoma, tumors with closely related histogenesis and antigenic profile. In addition to the improved tools available for serosal cancer diagnosis, knowledge regarding the biology of malignant mesothelioma has been accumulating in recent years. This review presents current data regarding the diagnostic and biological aspects of malignant mesothelioma.

Biomarkers for malignant pleural mesothelioma: current status

Malignant pleural mesothelioma (MPM) is an aggressive tumor with poor prognosis, whose main etiology is exposure to asbestos fibers. The incidence of MPM is anticipated to increase worldwide during the first half of this century. For various reasons, MPM is difficult to diagnose and is notoriously refractory to most treatments. However, recently two active chemotherapy regimens have been demonstrated to significantly increase survival in patients with MPM, and several therapeutic agents and strategies are currently under evaluation.Researchers have actively sought MPM biomarkers for more than 20 years. Biomarkers would be helpful in managing three clinical aspects of MPM: early diagnosis, prognosis, and treatment outcome prediction. The aims of the present review are to summarize the published and recently presented data on MPM biomarkers and to identify the prospects for future translational research projects.Among the 'classical' diagnostic biomarkers measured in biological fluids, such as cytokeratins and cell surface antigens, none discriminate patients with MPM from those with other malignancies and nonmalignant diseases. Osteopontin, soluble mesothelin, and megakaryocyte potentiating factor (MPF) appear to be the most promising of the recent biomarkers, but are still subject to some limitations. Osteopontin lacks specificity for mesothelioma, while both soluble mesothelin and MPF lack sensitivity for detecting non-epithelial subtypes. Panels consisting of a small set of biomarkers do not improve the diagnostic yield, and results from molecular profiling are too preliminary to be brought into daily clinical practice. While a large number of biomarkers have been assessed in biological fluids and tumor tissue for their prognostic value, none have had a widespread impact on clinical practice. In contrast, data concerning predictive biomarkers are very limited, even though they are most interesting from the perspective of clinicians.Additional prospective studies, in large and independent samples of patients, with rigorous statistical methodology and standardized laboratory techniques are now warranted to validate and define the precise value of diagnostic and prognostic MPM biomarkers. Future research efforts should focus on biomarkers predictive of the efficacy and toxicity of standard chemotherapy. Translational research should be systematically incorporated into the design of clinical trials assessing new targeted agents in MPM.

Expression patterns and prognostic significance of inhibitor of apoptosis proteins in adenoid cystic carcinoma and pleomorphic adenoma of lachrymal gland

It has been widely reported that IAPs family are overexpressed in various malignancies, and their expression patterns are associated with clinical outcome of these diseases. Adenoid cystic carcinoma (ACC) of lachrymal gland is a malignant tumor with a poor prognosis, while, pleomorphic adenoma (PA) is the benign tumor of lachrymal gland epithelia. It was the first time that we investigated the expression profile of IAPs in tissues from ACC and PA, and evaluated the prognostic significance of IAPs. Paraffin-embedded tissues with 27 cases of ACC and 33 cases of PA were enrolled, and another 17 fresh frozen tissues were also collected. Expression of cIAP1, cIAP2, XIAP, Survivin and Livin in embedded tissues was analyzed by immunohistochemistry, and expression of five IAPs in fresh tissues was evaluated by semiquantitive RT-PCR and Western blot. Prognostic significance of IAPs with clinicopathological variables and outcome was then investigated with univariate and multivariate analysis. Survivin and cIAP2 expression in ACC were significantly higher than that of in PA (p < 0.05). cIAP1 and XIAP tended to show stronger expression in ACC than in PA, although the differences were not statistically significant. Livin expression was almost undetectable in both malignancy and benign lesion of lachrymal gland. Survivin expression in lachrymal tumors was localized in cytoplasm exclusively, and its expression was related to T staging and proliferative index in ACC, multivariate analysis demonstrated that Survivin was the only factor that could independently predict poor prognosis of ACC (RR = 3.681, 95%CI: 1.068-12.688, p = 0.039). Furthermore, Survivin expression was associated with progression of PA. Expression of cIAP1, cIAP2, XIAP and Survivin was higher in ACC than in PA tissues, however, only differential expression of Survivin and cIAP2 between ACC and PA was significant. Different prognosis between ACC and PA might be attributable to the different expression profiles of IAPs. Overexpression of Survivin in ACC was associated with poorer survival, which may have clinical impact on diagnosis and therapeutic considerations of this malignancy.

High nuclear Livin expression is a favourable prognostic indicator in renal cell carcinoma

OBJECTIVES

To assess the protein expression of Livin, an apoptosis inhibitor, in renal cell carcinoma (RCC) and to determine its prognostic relevance.

PATIENTS AND METHODS

Immunohistochemical staining for Livin was performed in tissue microarrays (TMAs), including tumour tissue cores, from patients with RCC who had undergone renal surgery. In 682 TMAs cytoplasmatic staining intensity and nuclear staining quantity were evaluated, and the association of Livin expression with progression-free survival (PFS) and cancer-specific survival (CSS) was analysed with a multivariate Cox regression model.

RESULTS

Over a median (range) follow-up of 5.2 (0-16.1) years, 204 patients (28%) had died from their disease. The CSS rates at 1 and 5 years for the entire cohort was 88% and 71%. Cytoplasmatic Livin staining was absent in 516 (76%) specimens; staining was positive in 166 (24%) specimens. Weak nuclear Livin staining (<or=25%) was present in 571 (84%) specimens, strong nuclear staining (26-100%) in 111 (16%). In multivariate analysis, high (>25%) nuclear Livin expression was a favourable independent predictor of PFS and CSS even after adjusting for tumour stage, Fuhrman grade, age, sex and Karnofsky severity rating. Cytoplasmatic Livin expression did not offer additional prognostic information.

CONCLUSION

High nuclear Livin expression is a favourable independent predictor of PFS and CSS in patients with RCC.

Transcriptome sequencing of malignant pleural mesothelioma tumors

Cancers arise by the gradual accumulation of mutations in multiple genes. We now use shotgun pyrosequencing to characterize RNA mutations and expression levels unique to malignant pleural mesotheliomas (MPMs) and not present in control tissues. On average, 266 Mb of cDNA were sequenced from each of four MPMs, from a control pulmonary adenocarcinoma (ADCA), and from normal lung tissue. Previously observed differences in MPM RNA expression levels were confirmed. Point mutations were identified by using criteria that require the presence of the mutation in at least four reads and in both cDNA strands and the absence of the mutation from sequence databases, normal adjacent tissues, and other controls. In the four MPMs, 15 nonsynonymous mutations were discovered: 7 were point mutations, 3 were deletions, 4 were exclusively expressed as a consequence of imputed epigenetic silencing, and 1 was putatively expressed as a consequence of RNA editing. Notably, each MPM had a different mutation profile, and no mutated gene was previously implicated in MPM. Of the seven point mutations, three were observed in at least one tumor from 49 other MPM patients. The mutations were in genes that could be causally related to cancer and included XRCC6, PDZK1IP1, ACTR1A, and AVEN.

Expression of inhibitor of apoptosis protein Livin in renal cell carcinoma and non-tumorous adult kidney

The antiapoptotic Livin/ML-IAP gene has recently gained much attention as a potential new target for cancer therapy. Reports indicating that livin is expressed almost exclusively in tumours, but not in the corresponding normal tissue, suggested that the targeted inhibition of livin may present a novel tumour-specific therapeutic strategy. Here, we compared the expression of livin in renal cell carcinoma and in non-tumorous adult kidney tissue by quantitative real-time reverse transcription-PCR, immunoblotting, and immunohistochemistry. We found that livin expression was significantly increased in tumours (P=0.0077), but was also clearly detectable in non-tumorous adult kidney. Transcripts encoding Livin isoforms α and β were found in both renal cell carcinoma and normal tissue, without obvious qualitative differences. Livin protein in renal cell carcinoma samples exhibited cytoplasmic and/or nuclear staining. In non-tumorous kidney tissue, Livin protein expression was only detectable in specific cell types and restricted to the cytoplasm. Thus, whereas the relative overexpression of livin in renal cell carcinoma indicates that it may still represent a therapeutic target to increase the apoptotic sensitivity of kidney cancer cells, this strategy is likely to be not tumour-specific.

Human agonistic TRAIL receptor antibodies Mapatumumab and Lexatumumab induce apoptosis in malignant mesothelioma and act synergistically with cisplatin

Background

The incidence of malignant pleural mesothelioma (MPM) is associated with exposure to asbestos, and projections suggest that the yearly number of deaths in Western Europe due to MPM will increase until 2020. Despite progress in chemo- and in multimodality therapy, MPM remains a disease with a poor prognosis. Inducing apoptosis by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) or agonistic monoclonal antibodies which target TRAIL-receptor 1 (TRAIL-R1) or TRAIL-R2 has been thought to be a promising cancer therapy.

Results

We have compared the sensitivity of 13 MPM cell lines or primary cultures to TRAIL and two fully human agonistic monoclonal antibodies directed to TRAIL-R1 (Mapatumumab) and TRAIL-R2 (Lexatumumab) and examined sensitization of the MPM cell lines to cisplatin-induced by the TRAIL-receptor antibodies. We found that sensitivity of MPM cells to TRAIL, Mapatumumab and Lexatumumab varies largely and is independent of TRAIL-receptor expression. TRAIL-R2 contributes more than TRAIL-R1 to death-receptor mediated apoptosis in MPM cells that express both receptors. The combination of cisplatin with Mapatumumab or Lexatumumab synergistically inhibited the cell growth and enhanced apoptotic death. Furthermore, pre-treatment with cisplatin followed by Mapatumumab or Lexatumumab resulted in significant higher cytotoxic effects as compared to the reverse sequence. Combination-induced cell growth inhibition was significantly abrogated by pre-treatment of the cells with the antioxidant N-acetylcysteine.

Conclusion

Our results suggest that the sequential administration of cisplatin followed by Mapatumumab or Lexatumumab deserves investigation in the treatment of patients with MPM.

Preclinical studies of the proteasome inhibitor bortezomib in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a highly lethal neoplasm that is resistant to chemotherapy. Bortezomib is an FDA-approved proteasome inhibitor that is currently under clinical investigation in multiple neoplasms but has not been studied extensively in MPM. In this report, we determine the biological and molecular response of cultured MPM cells to bortezomib alone and in combination with cisplatin or pemetrexed. We used four MPM cell lines (MS589, H28, H2052, JMN), a normal mesothelial cell line (HM3), and a lung cancer cell line (H23) in survival studies utilizing bortezomib, cisplatin, and pemetrexed alone and in combination by administering concurrently or by varying the order of administration. We determined the effect of bortezomib on the cell cycle, apoptosis, and on the expression of cell cycle proteins p21/WAF1 and p27/KIP1 and on apoptosis-related proteins IAP-1, IAP-2, survivin, and XIAP. Bortezomib was highly cytotoxic to MPM cells and induced both G(2)/M and G(1)/S cell cycle arrest. Apoptosis increased in a concentration- and time-dependent manner in 3 of 4 MPM cell lines. Bortezomib stabilized or increased protein levels of p21/WAF1 and IAP-1 and to a lesser degree p27/KIP1, IAP-2, XIAP, and survivin. In combination studies with cisplatin, bortezomib was generally synergistic at high concentrations and antagonistic at low concentrations. Bortezomib increased the cytotoxicity of cisplatin and pemetrexed in a concentration-dependent manner when administered prior to either. Bortezomib may improve outcome in MPM patients alone or in combination with standard chemotherapy but the order of administration is likely to be important. This study justifies further evaluation of bortezomib in MPM.