Global histone modifications predict prognosis of resected non small-cell lung cancer.

PURPOSE: Epigenetic modifications may contribute to the development and progression of cancer. We investigated whether epigenetic changes involving multiple histones influence prognosis of non-small-cell lung cancer (NSCLC) patients. PATIENTS AND METHODS: We used immunohistochemistry to assess histone 3 lysine 4 dimethylation (H3K4diMe), and acetylation of histone 2A lysine 5 (H2AK5Ac), histone 2B lysine 12, histone 3 lysine 9 (H3K9Ac), and histone 4 lysine 8 in resected tumor samples of 138 NSCLC patients. Data were analyzed using a recursive partitioning analysis (RPA). RESULTS: The RPA classified the patients into seven distinct prognostic groups based on TNM stage (first node), histology, and histone modifications: H3K4diMe (< or 85% tumor cells), H3K9Ac (< or 68% tumor cells), and H2AK5Ac (< or 5% tumor cells). The seven groups were associated with significantly different disease-free (P < .0001) and overall survival (P < .0001). Interestingly, the four groups determined by stage I patients (below the first node) displayed dramatic differences in survival (median, 10 months in adenocarcinoma patients with H3K9Ac 68% v 147 months in nonadenocarcinoma patients with H3K4diMe 85%). A Cox model retained age and RPA groups as the sole independent factors significantly influencing overall survival. CONCLUSION: The prognostic influence of epigenetic changes involving multiple histones, in particular H2A and H3, is greater in early NSCLC, and evaluation of these changes may help in selecting early-stage NSCLC patients for adjuvant treatment. Our observations provide a rationale for the use of a combination of standard chemotherapy with drugs interacting with histone modifications, such as histone deacetylase inhibitors.

The expression of TUCAN, an inhibitor of apoptosis protein, in patients with advanced non-small cell lung cancer treated with chemotherapy.

BACKGROUND: TUCAN is a caspase recruitment domain (CARD)-containing protein involved in tumor biology by regulating apoptosis and the NFkappaB pathway. Inhibition of caspase-9 may cause drug resistance. The pattern of expression, localization and prognostic value of TUCAN in the tumors of patients with non-small cell lung cancer (NSCLC) treated with chemotherapy were assessed in this study. MATERIALS AND METHODS: Using immunohistochemistry, the expression and localization of TUCAN was evaluated in forty-nine tumor specimens from patients with NSCLC who underwent neoadjuvant chemotherapy (32 stage IIB or IIIA), or palliative chemotherapy (17 stage IIIB or IV). The correlation between TUCAN expression and subcellular localization, major patient characteristics, response to the treatment and overall survival were assessed. RESULTS: TUCAN expression was detectable in 34 out of 49 (69%) tumor specimens. Among the positively-stained specimens, three patterns of localization were observed: 5 samples (11%) showed exclusive nuclear localization, 13 samples (27%) contained only cytoplasmic staining and 15 (31%) showed both cytoplasmic and nuclear localization. There was no significant correlation between the localization of TUCAN and response to chemotherapy. Although TUCAN expression was not correlated with outcome, interestingly, exclusive cytoplasmic localization of TUCAN predicted shorter survival (p = 0.027). CONCLUSION: Our results suggest that differential localization of TUCAN may be a prognostic factor for NSCLC, despite the lack of predictive value for response to chemotherapy.

Uncoupling the central spindle-associated function of the chromosomal passenger complex from its role at centromeres.

Survivin is a component of the chromosomal passenger complex (CPC) that plays a role in maintenance of an active spindle checkpoint and in cytokinesis. To study whether these different functions can be attributed to distinct domains within the Survivin protein, we complemented Survivin-depleted cells with a variety of point- and deletion-mutants of Survivin. We show that an intact baculovirus IAP repeat (BIR) domain is required for proper spindle checkpoint functioning, but dispensable for cytokinesis. In line with this, mutants lacking an intact BIR domain localized normally to the central spindle, but their localization to inner centromeres was severely perturbed. Consequently, these mutants failed to recruit Aurora B, Borealin/Dasra B, and BubR1 to centromeres and kinetochores, but they had retained the ability to recruit Aurora B and Borealin/Dasra B to the midzone and midbody. Thus, the C terminus of Survivin is sufficient for central spindle localization and execution of cytokinesis, but the additional presence of a functional BIR domain is essential for centromere targeting and spindle checkpoint function. Importantly, our data show that the function of the CPC at the centromere can be separated from its function at the central spindle and that execution of cytokinesis does not require prior concentration of the CPC at centromeres.

Expression and localization of inhibitor of apoptosis proteins in normal human tissues.

The family of inhibitor of apoptosis (IAP) proteins can suppress apoptosis induced by a variety of triggers. Among the IAPs, cIAP1, cIAP2, and XIAP have been characterized as inhibitors of specific caspases, and their expression, together with that of survivin, has been shown in several studies to play a role as tumor marker and prognostic factor for the survival of patients with cancer. Although survivin is usually not expressed in normal adult tissues, cIAP1, cIAP2, and XIAP have been found broadly expressed at messenger RNA level within normal cells. Here, we report an immunohistochemical study in a comprehensive panel of normal human tissues, and we confirm at the protein level the wide expression of IAPs. These results are consistent with a physiological role of IAPs in normal cells. Moreover, we show that IAPs' expression levels and localization patterns differ depending on the cell lineage. The variable subcellular localization of the IAPs within different cell types suggests that compartmentalization may contribute to regulate their function. The physiological role of these proteins should be further investigated to help tailor IAP-targeted therapeutic strategies for patients with cancer and circumvent possible side effects.

FANCD2 expression in advanced non-small-cell lung cancer and response to platinum-based chemotherapy.

Fanconi's anemia (FA) is a genetically heterogeneous disease characterized by cancer susceptibility and hypersensitivity to cross-linking agents such as cisplatin. Recently, inactivation of the FA pathway has been proposed to contribute to genomic instability and an increased sensitivity to cisplatin-based therapy in a subset of ovarian tumors. Platinum-based chemotherapy constitutes standard systemic therapy for advanced non-small-cell lung cancer (NSCLC), but resistance to platinum chemotherapy is common. In this study, we evaluated the status of the FA pathway in tumor samples derived from patients with NSCLC in relation to their response to platinum-based chemotherapy. For this purpose, we assessed the expression of FANCD2 protein (a marker for FA pathway functioning) by immunohistochemistry in tumor specimens from 47 patients treated with platinum-based chemotherapy. FANCD2 expression could be detected in 32% of the cases (15 of 47). Expression of FANCD2 was not correlated with any patient or tumor characteristics, and FANCD2 expression was not a predictor of response to chemotherapy or patient survival. In conclusion, the activation status of the FA pathway had no value in predicting sensitivity to platinum-based chemotherapy in patients with advanced NSCLC.

Nuclear shuttling and TRAF2-mediated retention in the cytoplasm regulate the subcellular localization of cIAP1 and cIAP2.

Dynamic subcellular localization is an important regulatory mechanism for many proteins. cIAP1 and cIAP2 are two closely related members of inhibitor of apoptosis (IAP) family that play a role both as caspase inhibitors and as mediators of tumor necrosis factor (TNF) receptor signaling. Here, we report that cIAP1 and cIAP2 are nuclear shuttling proteins, whose subcellular localization is mediated by the CRM1-dependent nuclear export pathway. Blocking export with leptomycin B induces accumulation of both endogenous cIAP1 and epitope-tagged cIAP1 and cIAP2 in the nucleus of human cancer cells. We have identified a new CRM1-dependent leucine-rich nuclear export signal (NES) in the linker region between cIAP1 BIR2 and BIR3 repeats. Mutational inactivation of the NES, which is not conserved in cIAP2, reduces cIAP1 nuclear export. Forced relocation of cIAP1 to the nucleus did not significantly alter its ability to prevent apoptosis. Interestingly, co-expression experiments showed that the cIAP1 and cIAP2-interacting protein TNF receptor-associated factor 2 (TRAF2) plays an important role as regulator of IAP nucleocytoplasmic localization, by preventing nuclear translocation of cIAP1 and cIAP2. TRAF2-mediated cytoplasmic retention of cIAP1 was reduced upon TNFalpha treatment. Our results identify molecular mechanisms that contribute to regulate the subcellular localization of cIAP1 and cIAP2. Translocation between different cell compartments may add a further level of control for cIAP1 and cIAP2 activity.

Cathepsin B mediates caspase-independent cell death induced by microtubule stabilizing agents in non-small cell lung cancer cells.

We have previously reported that the microtubule stabilizing agents (MSAs) paclitaxel, epothilone B and discodermolide induce caspase-independent cell death in non-small cell lung cancer (NSCLC) cells. Here we present two lines of evidence indicating a central role for the lysosomal protease cathepsin B in mediating cell death. First, inhibition of cathepsin B, and not of caspases or other proteases, such as cathepsin D or calpains, results in a strong protection against drug-induced cell death in several NSCLC cells. Second, MSAs trigger disruption of lysosomes and release and activation of cathepsin B. Interestingly, inhibition of cathepsin B prevents the appearance of multinucleated cells, an early characteristic of MSA-induced cell death, pointing to a central, proximal role for cathepsin B in this novel cell death pathway.

Cisplatin triggers apoptotic or nonapoptotic cell death in Fanconi anemia lymphoblasts in a concentration-dependent manner.

Cells derived from Fanconi anemia (FA) patients are hypersensitive for cross-linking agents, such as cisplatin, that are potent inducers of programmed cell death (PCD). Here, we studied cisplatin hypersensitivity in FA in relation to the mechanism of PCD in lymphoblastoid cells representing FA groups A and C. In FA cells, a low concentration of cisplatin caused chromatin condensation, phosphatidylserine (PS) externalization, and the expression of an 18-kDa variant of Bax, all indicators of apoptotic cell death, and the latter suggesting the involvement of a mitochondrial route. However, procaspases-3, -8, and -9, and PARP were not cleaved, although small increases in caspase activity could be detected. At a high concentration of cisplatin, both FA and corrected cells showed a robust cleavage of procaspases and PARP. DNA fragmentation was clearly visible under high cisplatin conditions and to some extent at a low concentration in FA-A cells, but not in the FA-C cell line regardless of the presence of functional FANCC, suggesting an unknown deficiency in these cells. We conclude that hypersensitivity in FA cells is associated with a mixture of necrotic and apoptotic features that is best described as apoptotic-like cell death, and that a defective FA pathway does not interfere with the proper activation of caspase-mediated cell death.

Subcellular localization of CrmA: identification of a novel leucine-rich nuclear export signal conserved in anti-apoptotic serpins.

The cowpox virus-encoded anti-apoptotic protein cytokine response modifier A (CrmA) is a member of the serpin family that specifically inhibits the cellular proteins caspase 1, caspase 8 and granzyme B. In this study, we have used Flag- and yellow fluorescent protein (YFP)-tagged versions of CrmA to investigate the mechanisms that regulate its subcellular localization. We show that CrmA can actively enter and exit the nucleus and we demonstrate the role of the nuclear export receptor CRM1 in this shuttling process. CrmA contains a novel leucine-rich nuclear export signal (NES) that is functionally conserved in the anti-apoptotic cellular serpin PI-9. Besides this leucine-rich export signal, additional sequences mapping to a 103-amino-acid region flanking the NES contribute to the CRM1-dependent nuclear export of CrmA. Although YFP-tagged CrmA is primarily located in the cytoplasm, shifting its localization to be predominantly nuclear by fusion of a heterologous nuclear localization signal did not impair its ability to prevent Fas-induced apoptosis. We propose that nucleocytoplasmic shuttling would allow CrmA to efficiently target cellular pro-apoptotic proteins not only in the cytoplasm, but also in the nucleus, and thus to carry out its anti-apoptotic function in both compartments.

CRM1-mediated nuclear export determines the cytoplasmic localization of the antiapoptotic protein Survivin.

Survivin is a member of the inhibitor of apoptosis (IAP) family of negative regulators of programmed cell death that is frequently overexpressed in human tumors. Survivin is not only involved in the regulation of apoptosis, but is also known to play a role in the control of cell cycle progression at the G2/M phase. Survivin is a predominantly cytoplasmic protein expressed in a cell cycle-dependent manner, but the mechanism(s) that determine its nuclear-cytoplasmic localization have not been described. In this study, we report that Survivin is a nuclear shuttling protein that is actively exported from the nucleus via the CRM1-dependent pathway. Nuclear export of Survivin is independent of the export of other shuttling proteins that control the G2/M phase transition, such as cyclin B1 and cdc25. The carboxy-terminal domain of Survivin is both necessary and sufficient for its nuclear export, although this region does not contain a functional leucine-rich nuclear export signal. Differences in the amino acid sequence of this region determine the dramatically different localization of Survivin (in the cytoplasm) and its splicing variant Survivin-DeltaEx3 (in the nucleus). The carboxy-terminal end of Survivin-DeltaEx3 contains a bipartite nuclear localization signal, not present in Survivin, which mediates its strong nuclear accumulation. These data suggest that active transport between the nucleus and cytoplasm may constitute an important regulatory mechanism for Survivin function.