Mutations in BHD and TP53 genes, but not in HNF1beta gene, in a large series of sporadic chromophobe renal cell carcinoma

BHD, TP53, and HNF1β on chromosome 17 were studied in 92 cases of renal cell carcinoma (46 chromophobe, 19 clear cell, 18 oncocytoma, and nine papillary). Six, thirteen, and zero cases had, respectively BHD, TP53, and HNF1β mutations, (84% mutations involved chromophobe), suggesting a role for BHD and TP53 in chromophobe subtype.

Color bar coding the BRCA1 gene on combed DNA: a useful strategy for detecting large gene rearrangements

Genetic linkage data have shown that alterations of the BRCA1 gene are responsible for the majority of hereditary breast and ovarian cancers. BRCA1 germline mutations, however, are found less frequently than expected. Mutation detection strategies, which are generally based on the polymerase chain reaction, therefore focus on point and small gene alterations. These approaches do not allow for the detection of large gene rearrangements, which also can be involved in BRCA1 alterations. Indeed, a few of them, spread over the entire BRCA1 gene, have been detected recently by Southern blotting or transcript analysis. We have developed an alternative strategy allowing a panoramic view of the BRCA1 gene, based on dynamic molecular combing and the design of a full four-color bar code of the BRCA1 region. The strategy was tested with the study of four large BRCA1 rearrangements previously reported. In addition, when screening a series of 10 breast and ovarian cancer families negatively tested for point mutation in BRCA1/2, we found an unreported 17-kb BRCA1 duplication encompassing exons 3 to 8. The detection of rearrangements as small as 2 to 6 kb with respect to the normal size of the studied fragment is achieved when the BRCA1 region is divided into 10 fragments. In addition, as the BRCA1 bar code is a morphologic approach, the direct observation of complex and likely underreported rearrangements, such as inversions and insertions, becomes possible.

No evidence for germline PTEN mutations in families with breast and brain tumours

Germline mutations of the PTEN gene are involved in Cowden disease, a genetic condition associated with an increased risk of breast cancer. Further somatic PTEN mutations have been found in glioblastomas and to a lesser extent in meningiomas. Therefore, PTEN germline mutations were searched for in a series of 20 unrelated women with breast cancer who also had a personal or familial breast-brain tumour history. Inclusion criteria were 1. family history of breast cancer; 2. absence of germline BRCA1 and p53 mutation; and 3. at least one case of brain tumour (glioblastoma, meningioma, or medulloblastoma) in either the index case or one of their first or second degree relatives. Any stigmata of Cowden disease was an exclusion criteria. Screening of the PTEN gene for point mutations or small rearrangements were performed using the denaturing gradient gel electrophoresis method on the 9 coding exons. No disease-associated mutation of the PTEN gene has been detected in our series. It is, thus, unlikely that PTEN is a significant BRCA predisposing locus. However, one might ask whether breast cancer cases resulting from germline PTEN mutation could occur without any mammary histological feature of Cowden disease.

Biallelic hypomorphic mutations in HEATR5B, encoding HEAT repeat-containing protein 5B, in a neurological syndrome with pontocerebellar hypoplasia

HEAT repeats are 37-47 amino acid flexible tandem repeat structural motifs occurring in a wide variety of eukaryotic proteins with diverse functions. Due to their ability to undergo elastic conformational changes, they often serve as scaffolds at sites of protein interactions. Here, we describe four affected children from two families presenting with pontocerebellar hypoplasia manifest clinically with neonatal seizures, severe intellectual disability, and motor delay. Whole exome sequencing identified biallelic variants at predicted splice sites in intron 31 of HEATR5B, encoding the HEAT repeat-containing protein 5B segregating in a recessive fashion. Aberrant splicing was found in patient fibroblasts, which correlated with reduced levels of HEATR5B protein. HEATR5B is expressed during brain development in human, and we failed to recover live-born homozygous Heatr5b knockout mice. Taken together, our results implicate loss of HEATR5B in pontocerebellar hypoplasia.

Genetic testing for breast cancer predisposition

The recent identification of the BRCA1 and BRCA2 genes has improved our understanding of the association between breast and ovarian cancers in certain families. Carriers of predisposing germline mutations must decide on different options for management, including close follow-up or prophylactic surgery. Further studies are needed to elucidate the optimal management of these patients and to identify the factors that modify their risk for developing breast cancer. Finally, we must work to prevent any form of discrimination against those who, following genetic testing, are found to be at increased risk for breast cancer.

Preliminary Studies on Bemitradine-Induced Cardiotoxicity in Female Rats

The mechanism of bemitradine (SC-33643) cardiotoxicity in female rats was investigated in the set of preliminary experiments reported here. Specifically, the involvement of bemitradine metabolites and the potential role of adrenal epinephrine release were examined. Desethylbemi-tradine (the primary metabolite of bemitradine) was shown to be cardiotoxic at oral dosages greater than 300 mg/kg for 7 days. In a separate experiment, a major metabolite (bemitradine glycol) unique to the rat was not cardiotoxic at dosages up to 600 mg/kg for 7 days. Treatment of rats with SKF 525-A enhanced the lethality and the cardiotoxicity of bemitradine. In contrast, prior treatments of rats with phenobarbital resulted in decreased cardiotoxicity of both bemitradine and desethylbemitradine (a bemitradine metabolite presumably further metabolized by the microsomal mixed function oxidases). In other independent experiments, bemitradine-induced cardiotoxicity was shown to be accompanied by adrenal damage and decreases in adrenal epinephrine. Propranolol (a β-antagonist) treatment protected rats against cardiotoxicity. Bemitradine also had a direct effect on the heart, as evidenced in an experiment in which bemitradine caused dose-related increases in the T-wave of the rat ECG complex. These data suggest that (1) both bemitradine and desethylbemitradine may be responsible for the cardiotoxicity, and the other downstream metabolites are not and (2) cardiotoxicity may be due to the combination of direct effects of bemitradine on the rat heart and the bemitradine-mediated release of adrenal epinephrine (a known cardiotoxin at high circulating levels).

Inhibition of Abelson Tyrosine-Protein Kinase 2 Suppresses the Development of Alcohol-Associated Liver Disease by Decreasing PPARgamma Expression

BACKGROUND & AIMS

Alcohol-associated liver disease (ALD) represents a spectrum of alcohol use-related liver diseases. Outside of alcohol abstinence, there are currently no Food and Drug Administration-approved treatments for advanced ALD, necessitating a greater understanding of ALD pathogenesis and potential molecular targets for therapeutic intervention. The ABL-family proteins, including ABL1 and ABL2, are non-receptor tyrosine kinases that participate in a diverse set of cellular functions. We investigated the role of the ABL kinases in alcohol-associated liver disease.

METHODS

We used samples from patients with ALD compared with healthy controls to elucidate a clinical phenotype. We established strains of liver-specific Abl1 and Abl2 knockout mice and subjected them to the National Institute on Alcohol Abuse and Alcoholism acute-on-chronic alcohol feeding regimen. Murine samples were subjected to RNA sequencing, AST, Oil Red O staining, H&E staining, Western blotting, and quantitative polymerase chain reaction to assess phenotypic changes after alcohol feeding. In vitro modeling in HepG2 cells as well as primary hepatocytes from C57BL6/J mice was used to establish this mechanistic link of ALD pathogenesis.

RESULTS

We demonstrate that the ABL kinases are highly activated in ALD patient liver samples as well as in liver tissues from mice subjected to an alcohol feeding regimen. We found that the liver-specific knockout of Abl2, but not Abl1, attenuated alcohol-induced steatosis, liver injury, and inflammation. Subsequent RNA sequencing and gene set enrichment analyses of mouse liver tissues revealed that relative to wild-type alcohol-fed mice, Abl2 knockout alcohol-fed mice exhibited numerous pathway changes, including significantly decreased peroxisome proliferator activated receptor (PPAR) signaling. Further examination revealed that PPARγ, a previously identified regulator of ALD pathogenesis, was induced upon alcohol feeding in wild-type mice, but not in Abl2 knockout mice. In vitro analyses revealed that shRNA-mediated knockdown of ABL2 abolished the alcohol-induced accumulation of PPARγ as well as subsequent lipid accumulation. Conversely, forced overexpression of ABL2 resulted in increased PPARγ protein expression. Furthermore, we demonstrated that the regulation of hypoxia inducible factor 1 subunit alpha (HIF1α) by ABL2 is required for alcohol-induced PPARγ expression. Furthermore, treatment with ABL kinase inhibitors attenuated alcohol-induced PPARγ expression, lipid droplet formation, and liver injury.

CONCLUSIONS

On the basis of our current evidence, we propose that alcohol-induced ABL2 activation promotes ALD through increasing HIF1α and the subsequent PPARγ expression, and ABL2 inhibition may serve as a promising target for the treatment of ALD.

Adipsic hypernatremia and bilateral renal stones in a child with ectrodactyly-ectodermal dysplasia-cleft lip-palate (EEC) syndrome

EEC syndrome an autosomal dominant disorder with variable expression and cardinal signs of ectrodactyly, ectodermal dysplasia, and orofacial clefts. In this report, we describe a patient with EEC syndrome, adipsic hypernatremia without brain anomalies, and bilateral renal stones, two manifestations that were not reported before.

Abstract B41: Transcriptome-wide profiling identifies novel differential genes associated with health disparity of prostate cancer

Background: The incidence and mortality rates of prostate cancer (PCa) are twice as high in African American (AA) than in Caucasian American (CA) men. The molecular alterations associated with this racial disparity have not been fully elucidated. We aim to compare the expression profile of AA and CA men using microarray available data and paraffin-embedded tissues to identify the underlying molecular mechanisms contributing to the disproportionate of PCa among AA men.

Methods: Microarray data of 619 PCa patients, 412 AA and 207 CA, were retrieved from 11 data sets deposited in Gene Expression Omnibus (GEO) database. False discovery rates (FDR) were used for reporting differentially expressed genes and the differentially regulated pathways of these genes were predicted. To validate the microarray data, qPCR analyses were performed in forty paraffin-embedded samples collected from AA and CA men.

Results: Of 362 differential transcripts of array data, TIMP4, LTC4S, SHH, ADIPOQ, and ALOX12 were downregulated (p<0.001) while KLK2, COX5A, AZGP1, AMD1, and ALDH1A3 were upregulated (p<0.001) in PCa AA compared to CA men. qPCR analyses demonstrated that OAT, NKX3, LTC4S, APPL2, TPD52, ALDH, and AMD1 were significantly upregulated (p<0.05) in AA regarding CA men with PCa. Overexpression of OAT, LTC4S, and TPD52 in AA cell lines was confirmed by Western blot analysis. These genes were involved in regulation of cell apoptosis, lipid metabolism, migration, angiogenesis, and response to reactive oxygen species. These transcripts are involved in focal adhesion, PI3K/Akt, EGFR, beta-catenin, and MAPK signaling pathways.

Conclusions: Gene expression data from PCa specimens and microarray suggest that dysregulation of transcripts in PCa of AA compared to CA men may underlie health disparity of PCa. These data might provide new insights into development of reliable diagnostic and prognostic markers of aggressive PCa.

Citation Format: Hamdy Ali, Pei-Yau Lung, Shaimaa Gad, Andrew Sholl, Hamed I. Ali, Jinfeng Zhang, Zakaria Y. Abd Elmageed. Transcriptome-wide profiling identifies novel differential genes associated with health disparity of prostate cancer [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr B41.