Metabolic control of PPAR activity by aldehyde dehydrogenase regulates invasive cell behavior and predicts survival in hepatocellular and renal clear cell carcinoma.

BACKGROUND: Changes in cellular metabolism are now recognized as potential drivers of cancer development, rather than as secondary consequences of disease. Here, we explore the mechanism by which metabolic changes dependent on aldehyde dehydrogenase impact cancer development. METHODS: ALDH7A1 was identified as a potential cancer gene using a Drosophila in vivo metastasis model. The role of the human ortholog was examined using RNA interference in cell-based assays of cell migration and invasion. 1H-NMR metabolite profiling was used to identify metabolic changes in ALDH7A1-depleted cells. Publically available cancer gene expression data was interrogated to identify a gene-expression signature associated with depletion of ALDH7A1. Computational pathway and gene set enrichment analysis was used to identify signaling pathways and cellular processes that were correlated with reduced ALDH7A1 expression in cancer. A variety of statistical tests used to evaluate these analyses are described in detail in the methods section. Immunohistochemistry was used to assess ALDH7A1 expression in tissue samples from cancer patients. RESULTS: Depletion of ALDH7A1 increased cellular migration and invasiveness in vitro. Depletion of ALDH7A1 led to reduced levels of metabolites identified as ligands for Peroxisome proliferator-activated receptor (PPARα). Analysis of publically available cancer gene expression data revealed that ALDH7A1 mRNA levels were reduced in many human cancers, and that this correlated with poor survival in kidney and liver cancer patients. Using pathway and gene set enrichment analysis, we establish a correlation between low ALDH7A1 levels, reduced PPAR signaling and reduced patient survival. Metabolic profiling showed that endogenous PPARα ligands were reduced in ALDH7A1-depleted cells. ALDH7A1-depletion led to reduced PPAR transcriptional activity. Treatment with a PPARα agonist restored normal cellular behavior. Low ALDH7A1 protein levels correlated with poor clinical outcome in hepatocellular and renal clear cell carcinoma patients. CONCLUSIONS: We provide evidence that low ALDH7A1 expression is a useful prognostic marker of poor clinical outcome for hepatocellular and renal clear cell carcinomas and hypothesize that patients with low ALDH7A1 might benefit from therapeutic approaches addressing PPARα activity.

The Danish Testicular Cancer database.

AIM: The nationwide Danish Testicular Cancer database consists of a retrospective research database (DaTeCa database) and a prospective clinical database (Danish Multidisciplinary Cancer Group [DMCG] DaTeCa database). The aim is to improve the quality of care for patients with testicular cancer (TC) in Denmark, that is, by identifying risk factors for relapse, toxicity related to treatment, and focusing on late effects. STUDY POPULATION: All Danish male patients with a histologically verified germ cell cancer diagnosis in the Danish Pathology Registry are included in the DaTeCa databases. Data collection has been performed from 1984 to 2007 and from 2013 onward, respectively. MAIN VARIABLES AND DESCRIPTIVE DATA: The retrospective DaTeCa database contains detailed information with more than 300 variables related to histology, stage, treatment, relapses, pathology, tumor markers, kidney function, lung function, etc. A questionnaire related to late effects has been conducted, which includes questions regarding social relationships, life situation, general health status, family background, diseases, symptoms, use of medication, marital status, psychosocial issues, fertility, and sexuality. TC survivors alive on October 2014 were invited to fill in this questionnaire including 160 validated questions. Collection of questionnaires is still ongoing. A biobank including blood/sputum samples for future genetic analyses has been established. Both samples related to DaTeCa and DMCG DaTeCa database are included. The prospective DMCG DaTeCa database includes variables regarding histology, stage, prognostic group, and treatment. CONCLUSION: The DMCG DaTeCa database has existed since 2013 and is a young clinical database. It is necessary to extend the data collection in the prospective database in order to answer quality-related questions. Data from the retrospective database will be added to the prospective data. This will result in a large and very comprehensive database for future studies on TC patients.

Expression pattern of clinically relevant markers in paediatric germ cell- and sex-cord stromal tumours is similar to adult testicular tumours.

Paediatric germ cell tumours (GCTs) are rare and account for less than 3 % of childhood cancers. Like adult GCTs, they probably originate from primordial germ cells, but the pattern of histopathological types is different, and they occur predominantly in extragonadal sites along the body midline. Because they are rare, histology of paediatric GCTs is poorly documented, and it remains unclear to what extent they differ from adult GCTs. We have analysed 35 paediatric germ cell tumours and 5 gonadal sex-cord stromal tumours from prepubertal patients aged 0-15 years, to gain further knowledge, elaborate on clinical-pathological associations and better understand their developmental divergence. The tumours were screened for expression of stemness-related factors (OCT4, AP-2γ, SOX2), classical yolk sac tumours (YSTs; AFP, SALL4), GCTs (HCG, PLAP, PDPN/D2-40), as well as markers for sex-cord stromal tumour (PDPN, GATA4). All YSTs expressed AFP and SALL4, with GATA4 present in 13/14. The majority of teratomas expressed SOX2 and PDPN, whereas SALL4 was found in 8/13 immature teratomas. Adult seminoma markers AP-2γ, OCT4, SALL4 and PDPN were all expressed in dysgerminoma. We further report a previously unrecognised pathogenetic relationship between AFP and SALL4 in YST in that different populations of YST cells express either SALL4 or AFP, which suggests variable differentiation status. We also show that AP-2γ is expressed in the granulosa layer of ovarian follicles and weakly expressed in immature but not in mature granulosa cell tumours. Our findings indicate that the expression pattern of these antigens is similar between paediatric and adult GCTs, even though they develop along different developmental trajectories.