Correction to: BRG1 regulation by miR-155 in human leukemia and lymphoma cell lines

Following the publication of the original article the author listed as Antonio Herrera contacted the Publisher to state that his correct and full name is Antonio Herrera-Merchan. Antonio Herrera-Merchan has agreed to the publication of this erratum.

Expression signatures in lung cancer reveal a profile for EGFR-mutant tumours and identify selective PIK3CA overexpression by gene amplification

The development of targeted therapies creates a need to discriminate tumours accurately by their histological and genetic characteristics. Here, we aim to identify gene expression profiles and single markers that recapitulate the pathological and genetic background of non-small cell lung cancer (NSCLC). We performed cDNA microarray analysis on a series of 69 NSCLCs, with known mutation status for important genes, and six normal lung tissues. Unsupervised cluster analysis segregated normal lungs from lung tumours and lung tumours according to their histopathology and the presence of EGFR mutations. Several transcripts were highly overexpressed (by approximately 20 times) in squamous cell carcinomas (SCCs) relative to adenocarcinomas (ACs) and confirmed by immunohistochemistry in an independent cohort of 75 lung tumours. Expression of 13 genes constituted the most prominent hallmarks of EGFR-mutant tumours, including increased levels of proline dehydrogenase (PRODH) and down-regulation of X-box binding protein 1 (XBP1). No genes were differentially expressed, with a fold change >or= 4 or <or=0.25 and a significance level of 5% false-discovery rate, in tumours carrying mutations of TP53 or KRAS. In addition, we organized gene expression data by the position of each gene in the chromosome and observed a cluster of highly expressed genes in chromosome 3q, including PIK3CA, that was characteristic of SCCs. FISH analysis demonstrated a strong statistically significant association between increased levels of PIK3CA expression in these tumours and gene amplification (p < 0.0001; t-test). In conclusion, histopathological phenotypes and, likely, the presence of EGFR mutations confer lung tumours with a marked pattern of gene expression. Moreover, our cDNA microarray analysis identified increased PIK3CA expression due to gene amplification in lung squamous cell carcinomas: this may represent a marker of sensitivity to therapy with PI3K inhibitors.

Dysfunctional AMPK activity, signalling through mTOR and survival in response to energetic stress in LKB1-deficient lung cancer

LKB1, mutated in Peutz-Jeghers and in sporadic lung tumours, phosphorylates a group of protein kinases named AMP-activated protein kinase (AMPK)-related kinases. Among them is included the AMPK, a sensor of cellular energy status. To investigate the relevance of LKB1 in lung carcinogenesis, we study several lung cancer cells with and without LKB1-inactivating mutations. We report that LKB1-mutant cells are deficient for AMPK activity and refractory to mTOR inhibition upon glucose depletion but not growth-factor deprivation. The requirement for wild-type LKB1 to properly activate AMPK is further demonstrated in genetically modified cancer cells. In addition, LKB1-deficient lung primary tumours had diminished AMPK activity, assessed by complete absence or low level of phosphorylation of its critical substrate, acetyl-CoA carboxylase. We also demonstrate that LKB1 wild-type cells are more resistant to cell death upon glucose withdrawal than their mutant counterparts. Finally, modulation of AMPK activity did not affect PI3K/AKT signalling, an advantage for the potential use of AMPK as a target for cancer therapy in LKB1 wild-type tumours. Thus, sustained abrogation of cell energetic checkpoint control, through alterations at key genes, appear to be an obligatory step in the development of some lung tumours.

DNA-repair gene (DRG) single nucleotide polymorphisms (SNPs) influence on response and survival in stage IV SCCHN patients treated with CDDP-based therapy

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Background: CDDP kills tumor cells by DNA cross-linking. SNPS at DRG may influence the ability of patients to respond to CDDP. We studied the role of the SNPs XPD-Asp312Asn, XPD-Lys751Gln, ERCC1-C8092A and XRCC1-Arg399Gln to influence the response to CDDP-based therapy and to predict survival in SCCHN patients Methods: SNPs were genotyped in DNA from peripheral lymphocytes using PCR-restriction fragment length polymorphism in 103 stage IV (0% M1) SCCHN patients followed prospectively. Treatment schedules were concurrent CDDP/RT (n = 28), CDDP + fluoropyrimidine (FP)→ CDDP/RT (33) or CDDP + FP + taxane→CDDP/RT (42). Endpoints: to assess the impact of the SNPs in OS (Kaplan Meier and Cox’s model) and in response to chemotherapy (multivariate multinomial regression). The covariables gender, age, treatment type, number of polymorphic (poly.) variants (0–8), smoking and alcohol consumption and amount (mg) of CDDP were included in the multivariate analysis Results: Median age 60 yrs (39–94); 97 (94%) male. After 78 months of follow-up, 24% had died, 22% had relapsed and 51% were free of disease. The allele frequencies for the homozygous common allele, heterozygous and homozygous poly. variant were: ERCC1: 53, 40 and 7%; XPD312: 50, 42 and 8%; XPD751: 35, 57 and 8%; XRCC1: 35, 51 and 13%. Overall, 9%, 16%, 22%, 20%, 24%, 6%, 1% and 1% of the patients harbored 0, 1, 2, 3, 4, 5, 6 and 7 poly. variants simultaneously. Table shows OS according to genotype. Patients with only common alleles had a median OS of 5.1 months (4.3–6.0) vs not reached for patients with ≥1 variant (p = 0.0000)(mean 6.2 (4–8.4) vs 61.3 (53–59.8). Each variant allele decreases the probability of dying 2.1 fold (p = 0.0000) on the Cox’s analysis (7 variants = 175 fold protection) and increases 2.94 fold (multinom. reg.)the probability of achieving a CR vs PD (p = 0.041) Conclusions: In our series the poly. variants at DRG are the strongest prognosis factors and accurately predict clinical response among SCCHN patients.

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No significant financial relationships to disclose.