Camilla Krakstad

Landscape of genomic alterations in cervical carcinomas

Cervical cancer is responsible for 10–15% of cancer-related deaths in women worldwide. The aetiological role of infection with high-risk human papilloma viruses (HPVs) in cervical carcinomas is well established. Previous studies have also implicated somatic mutations in PIK3CA, PTEN, TP53, STK11 and KRAS as well as several copy-number alterations in the pathogenesis of cervical carcinomas. Here we report whole-exome sequencing analysis of 115 cervical carcinoma–normal paired samples, transcriptome sequencing of 79 cases and whole-genome sequencing of 14 tumour–normal pairs. Previously unknown somatic mutations in 79 primary squamous cell carcinomas include recurrent E322K substitutions in the MAPK1 gene (8%), inactivating mutations in the HLA-B gene (9%), and mutations in EP300 (16%), FBXW7 (15%), NFE2L2 (4%), TP53 (5%) and ERBB2 (6%). We also observe somatic ELF3 (13%) and CBFB (8%) mutations in 24 adenocarcinomas. Squamous cell carcinomas have higher frequencies of somatic nucleotide substitutions occurring at cytosines preceded by thymines (Tp*C sites) than adenocarcinomas. Gene expression levels at HPV integration sites were statistically significantly higher in tumours with HPV integration compared with expression of the same genes in tumours without viral integration at the same site. These data demonstrate several recurrent genomic alterations in cervical carcinomas that suggest new strategies to combat this disease.

Survival signalling and apoptosis resistance in glioblastomas: opportunities for targeted therapeutics.

Glioblastoma multiforme (GBM) is the most common primary brain tumour in adults and one of the most aggressive cancers in man. Despite technological advances in surgical management, combined regimens of radiotherapy with new generation chemotherapy, the median survival for these patients is 14.6 months. This is largely due to a highly deregulated tumour genome with opportunistic deletion of tumour suppressor genes, amplification and/or mutational hyper-activation of receptor tyrosine kinase receptors. The net result of these genetic changes is augmented survival pathways and systematic defects in the apoptosis signalling machinery. The only randomised, controlled phase II trial conducted targeting the epidermal growth factor receptor (EGFR) signalling with the small molecule inhibitor, erlotinib, has showed no therapeutic benefit. Survival signalling and apoptosis resistance in GBMs can be viewed as two sides of the same coin. Targeting increased survival is unlikely to be efficacious without at the same time targeting apoptosis resistance. We have critically reviewed the literature regarding survival and apoptosis signalling in GBM, and highlighted experimental, preclinical and recent clinical trials attempting to target these pathways. Combined therapies simultaneously targeting apoptosis and survival signalling defects might shift the balance from tumour growth stasis to cytotoxic therapeutic responses that might be associated with greater therapeutic benefits.

cAMP effector mechanisms. Novel twists for an ‘old’ signaling system

Cyclic AMP (cAMP) has traditionally been thought to act exclusively through cAMP‐dependent protein kinase (cAPK, PKA), but a growing number of cAMP effects are not attributable to general activation of cAPK. At present, cAMP is known also to directly regulate ion channels and the ubiquitous Rap guanine exchange factors Epac 1 and 2. Adding to the sophistication of cAMP signaling is the fact that (1) the cAPK holoenzyme is incompletely dissociated even at saturating cAMP, the level of free R subunit of cAPK being able to regulate the maximal activity of cAPK, (2) cAPK activity can be modulated by oxidative glutathionylation, and (3) cAPK is anchored close to relevant substrates, other signaling enzymes, and local compartments of cAMP. Finally, we will demonstrate an example of fine‐tuning of cAMP signaling through synergistic induction of neurite extensions by cAPK and Epac.

The progenitor cell marker NG2/MPG promotes chemoresistance by activation of integrin-dependent PI3K/Akt signaling

Chemoresistance represents a major problem in the treatment of many malignancies. Overcoming this obstacle will require improved understanding of the mechanisms responsible for this phenomenon. The progenitor cell marker NG2/melanoma proteoglycan (MPG) is aberrantly expressed by various tumors, but its role in cell death signaling and its potential as a therapeutic target are largely unexplored. We have assessed cytotoxic drug-induced cell death in glioblastoma spheroids from 15 patients, as well as in five cancer cell lines that differ with respect to NG2/MPG expression. The tumors were treated with doxorubicin, etoposide, carboplatin, temodal, cisplatin and tumor necrosis factor (TNF)α. High NG2/MPG expression correlated with multidrug resistance mediated by increased activation of α3β1 integrin/PI3K signaling and their downstream targets, promoting cell survival. NG2/MPG knockdown with shRNAs incorporated into lentiviral vectors attenuated β1 integrin signaling revealing potent antitumor effects and further sensitized neoplastic cells to cytotoxic treatment in vitro and in vivo. Thus, as a novel regulator of the antiapoptotic response, NG2/MPG may represent an effective therapeutic target in several cancer subtypes.

Lack of Estrogen Receptor-α Is Associated with Epithelial–Mesenchymal Transition and PI3K Alterations in Endometrial Carcinoma

Purpose: We hypothesized that estrogen receptor-α (ER-α) status in endometrial carcinomas, associated with poor prognosis, is reflected in transcriptional signatures suggesting targets for new therapy. Experimental Design: Endometrial carcinoma samples in a primary investigation cohort (n = 76) and three independent validation cohorts (n = 155/286/111) were analyzed through integrated molecular profiling. Biomarkers were assessed by immunohistochemistry (IHC), DNA oligonucleotide microarray, quantitative PCR (qPCR), single-nucleotide polymorphism (SNP) array, and Sanger sequencing in the cohorts, annotated for comprehensive histopathologic and clinical data, including follow-up. Results: ER-α immunohistochemical staining was strongly associated with mRNA expression of the receptor gene (ESR1) and patient survival (both P < 0.001). ER-α negativity associated with activation of genes involved in Wnt-, Sonic Hedgehog-, and TGF-β signaling in the investigation cohort, indicating epithelial–mesenchymal transition (EMT). The association between low ER-α and EMT was validated in three independent datasets. Furthermore, phosphoinositide 3-kinase (PI3K) and mTOR inhibitors were among the top-ranked drug signatures negatively correlated with the ER-α–negative tumors. Low ER-α was significantly associated with PIK3CA amplifications but not mutations. Also, low ER-α was correlated to high expression of Stathmin, a marker associated with PTEN loss, and a high PI3K activation signature. Conclusion: Lack of ER-α in endometrial cancer is associated with EMT and reduced survival. We present a rationale for investigating ER-αs potential to predict response to PI3K/mTOR inhibitors in clinical trials and also suggest EMT inhibitors to ER-α–negative endometrial carcinomas. Clin Cancer Res; 19(5); 1094–105. ©2012 AACR.

The genomic landscape and evolution of endometrial carcinoma progression and abdominopelvic metastasis

Recent studies have detailed the genomic landscape of primary endometrial cancers, but the evolution of these cancers into metastases has not been characterized. We performed whole-exome sequencing of 98 tumor biopsies including complex atypical hyperplasias, primary tumors and paired abdominopelvic metastases to survey the evolutionary landscape of endometrial cancer. We expanded and reanalyzed The Cancer Genome Atlas (TCGA) data, identifying new recurrent alterations in primary tumors, including mutations in the estrogen receptor cofactor gene NRIP1 in 12% of patients. We found that likely driver events were present in both primary and metastatic tissue samples, with notable exceptions such as ARID1A mutations. Phylogenetic analyses indicated that the sampled metastases typically arose from a common ancestral subclone that was not detected in the primary tumor biopsy. These data demonstrate extensive genetic heterogeneity in endometrial cancers and relative homogeneity across metastatic sites.

Hormone receptor loss in endometrial carcinoma curettage predicts lymph node metastasis and poor outcome in prospective multicentre trial

BACKGROUND Preoperative histologic examination of tumour tissue is essential when deciding if endometrial cancer surgery should include lymph node sampling. We wanted to investigate if biomarkers could improve prediction of lymph node metastasis and outcome. PATIENTS AND METHODS Curettage specimens from 832 endometrial carcinoma patients prospectively recruited from 10 centres in the MoMaTEC trial (Molecular Markers in Treatment of Endometrial Cancer) were investigated for hormone receptor and p53 status. RESULTS Eighteen per cent of tumours were double negative for oestrogen- and progesterone receptors (ER/PR loss), 24% overexpressed p53. Pathologic expression of all markers correlated with nodal metastases, high FIGO (Federation International of Gynecology and Obstetrics) stage, non-endometrioid histology, high grade and poor prognosis (all P<0.001). ER/PR loss independently predicted lymph node metastasis (odds ratios (OR) 2.0, 95% confidence interval (CI) 1.1-3.7) adjusted for preoperative curettage histology and predicted poor disease-specific survival adjusted for age, FIGO stage, histologic type, grade and myometrial infiltration (hazard ratio (HR) 2.3, 95% CI 1.4-3.9). For lymph node negative endometrioid tumours, ER/PR loss influenced survival independent of grade. CONCLUSION Double negative hormone receptor status in endometrial cancer curettage independently predicts lymph node metastasis and poor prognosis in a prospective multicentre setting. Implementing hormone receptor status to improve risk-stratification for selecting patients unlikely to benefit from lymphadenectomy seems justified.

Integrated Genomic Analysis of the 8q24 Amplification in Endometrial Cancers Identifies ATAD2 as Essential to MYC-Dependent Cancers

Chromosome 8q24 is the most commonly amplified region across multiple cancer types, and the typical length of the amplification suggests that it may target additional genes to MYC. To explore the roles of the genes most frequently included in 8q24 amplifications, we analyzed the relation between copy number alterations and gene expression in three sets of endometrial cancers (N = 252); and in glioblastoma, ovarian, and breast cancers profiled by TCGA. Among the genes neighbouring MYC, expression of the bromodomain-containing gene ATAD2 was the most associated with amplification. Bromodomain-containing genes have been implicated as mediators of MYC transcriptional function, and indeed ATAD2 expression was more closely associated with expression of genes known to be upregulated by MYC than was MYC itself. Amplifications of 8q24, expression of genes downstream from MYC, and overexpression of ATAD2 predicted poor outcome and increased from primary to metastatic lesions. Knockdown of ATAD2 and MYC in seven endometrial and 21 breast cancer cell lines demonstrated that cell lines that were dependent on MYC also depended upon ATAD2. These same cell lines were also the most sensitive to the histone deacetylase (HDAC) inhibitor Trichostatin-A, consistent with prior studies identifying bromodomain-containing proteins as targets of inhibition by HDAC inhibitors. Our data indicate high ATAD2 expression is a marker of aggressive endometrial cancers, and suggest specific inhibitors of ATAD2 may have therapeutic utility in these and other MYC-dependent cancers.

cAMP protects neutrophils against TNF-α-induced apoptosis by activation of cAMP-dependent protein kinase, independently of exchange protein directly activated by cAMP (Epac)

It is unclear by which receptor cyclic adenosine monophosphate (cAMP) acts to promote neutrophil survival. We found that 8‐(4‐chlorophenylthio)‐2′‐O‐methyl‐cAMP, a specific activator of the recently discovered cAMP receptor, cAMP‐regulated guanosine 5′‐triphosphate exchange protein directly activated by cAMP, failed to protect human neutrophils from cell death. In contrast, specific activators of cAMP‐dependent protein kinase type I (cA‐PKI) could protect against death receptor [tumor necrosis factor receptor 1 (TNFR‐1), Fas]‐mediated apoptosis as well as cycloheximide‐accelerated “spontaneous” apoptosis. A novel “caged” cA‐PK‐activating analog, 8‐bromo (8‐Br)‐acetoxymethyl‐cAMP, was more than 20‐fold more potent than 8‐Br‐cAMP to protect neutrophils chalenged with TNF‐α against apoptosis. This analog acted more rapidly than forskolin (which increases the endogenous cAMP production) and allowed us to demonstrate that cA‐PK must be activated during the first 10 min after TNF‐α challenge to protect against apoptosis. The protective effect was mediated solely through cA‐PK activation, as it was abolished by the cA‐PKI‐directed inhibitor Rp‐8‐Br‐cAMPS and the general cA‐PK inhibitor H‐89. Neutrophils not stimulated by cAMP‐elevating agents showed increased apoptosis when exposed to the cA‐PK inhibitors Rp‐8‐Br‐cAMPS and H‐89, suggesting that even moderate activation of cA‐PK is sufficient to enhance neutrophil longevity and thereby contribute to neutrophil accumulation in chronic inflammation.

CaM-kinaseII-dependent commitment to microcystin- induced apoptosis is coupled to cell budding, but not to shrinkage or chromatin hypercondensation

The protein phosphatase inhibitor microcystin-LR (MC) induced hepatocyte apoptosis mediated by the calcium-calmodulin-dependent multifunctional protein kinase II (CaMKII). CaMKII antagonists were added at various times after MC to define for how long the cells depended on CaMKII activity to be committed to execute the various parameters of death. Shrinkage and nonpolarized budding were reversible and not coupled to commitment. A critical commitment step was observed 15–20 min after MC (0.5 μM) addition. After this, CaMKII inhibitors no longer protected against polarized budding, DNA fragmentation, lost protein synthesis capability, and cell disruption. Commitment to chromatin hypercondensation occurred 40 min after MC addition. In conclusion, irreversible death commitment was coupled to polarized budding, but not to shrinkage or chromatin condensation. Antioxidant prevented chromatin condensation when given after the CaMKII-dependent commitment point, suggesting that CaMKII had mediated the accumulation of a second messenger of reactive oxygen species nature.