Biallelic loss-of-function variants in WDR11 are associated with microcephaly and intellectual disability.

Heterozygous missense variants in the WD repeat domain 11 (WDR11) gene are associated with hypogonadotropic hypogonadism in humans. In contrast, knockout of both alleles of Wdr11 in mice results in a more severe phenotype with growth and developmental delay, features of holoprosencephaly, heart defects and reproductive disorders. Similar developmental defects known to be associated with aberrant hedgehog signaling and ciliogenesis have been found in zebrafish after Wdr11 knockdown. We here report biallelic loss-of-function variants in the WDR11 gene in six patients from three independent families with intellectual disability, microcephaly and short stature. The findings suggest that biallelic WDR11 variants in humans result in an overlapping but milder phenotype compared to Wdr11-deficient animals. However, the observed human phenotype differs significantly from dominantly inherited variants leading to hypogonadotropic hypogonadism, suggesting that recessive WDR11 variants result in a clinically distinct entity.

Cell-specific RNA interference by peptide-inhibited-peptidase-activated siRNAs.

The use of chemically-synthesized short interfering RNAs (siRNAs) is the key method of choice to manipulate gene expression in mammalian cell cultures and in vivo. Several previous studies have aimed at inducing cell-specific RNA interference (RNAi) in order to use siRNA molecules as therapeutic reagents. Here, we used peptide-inhibited siRNAs that were activated after cleavage by cell-specific peptidases. We show that siRNAs with bound peptide at the antisense strand could be activated in target cells and were able to induce RNAi in a cell-specific manner. Green Fluorescent Protein (GFP) and Signal Transducer and Activator of Transcription (STAT)-3 gene expression were selectively reduced in a JEG-3 human choriocarcinoma cell line expressing the activating enzyme caspase-4, whereas the effect was absent in HEK cells which lacked the enzyme. In JEG-3 cells, reduction of STAT3 gene expression by conventional and peptide-inhibited siRNA led to a decrease in cell proliferation. This suggests that peptide-inhibited siRNAs provide improved cell specificity and offers new opportunities for their therapeutic use.

The gut fermentation product butyrate, a chemopreventive agent, suppresses glutathione S-transferase theta (hGSTT1) and cell growth more in human colon adenoma (LT97) than tumor (HT29) cells.

PURPOSE: The gut fermentation product of dietary fiber, butyrate, inhibits growth of HT29, an established tumor cell line. It also induces detoxifying enzymes belonging to the glutathione S-transferase family (GSTs), namely hGSTM2, hGSTP1, hGSTA4, but not of hGSTT1 . Here we investigated kinetics of effects in HT29 and compared sensitivities with preneoplastic LT97 colon adenoma cells, to assess mechanisms of colon cancer chemoprevention in two stages of cell transformation. METHODS: We determined cell growth after butyrate treatment by quantifying DNA, GST expression by Northern/Western Blotting or biochemical analysis and butyrate consumption by measuring the residual concentrations in the cell culture supernatants. Stability of GST-theta (hGSTT1) mRNA was assessed in HT29 cells after inhibition of transcription with actinomycin D. RESULTS: LT97 adenoma cells consumed twofold more butyrate and were more sensitive to growth inhibition than HT29 (EC(50)1.9 mM and 4.0 mM, respectively). Butyrate did not induce GSTs, but instead reduced hGSTT1 in LT97 and HT29. CONCLUSIONS: Butyrate has suppressing-agent activities in human colon cells by inhibiting two survival factors, namely hGSTT1 and cell growth, with LT97 more sensitive than HT29. These findings indicate that butyrate formation in the gut lumen of humans could be protective by reducing survival of transformed colon cells.

Human adenoma cells are highly susceptible to the genotoxic action of 4-hydroxy-2-nonenal.

Oxidative stress and resulting lipid peroxidation are important risk factors for dietary-associated colon cancer. To get a better understanding of the underlying molecular mechanisms, we need to characterise the risk potential of the key compounds, which cause DNA damage in cancer-relevant genes and especially in human target cells. Here, we investigated the genotoxic effects of 4-hydroxy-2-nonenal (HNE) and hydrogen peroxide (H(2)O(2)) in human colon cells (LT97). LT97 is a recently established cell line from a differentiated microadenoma and represents cells from frequent preneoplastic lesions of the colon. The genomic characterisation of LT97 was performed with 24-colour FISH. Genotoxicity was determined with single cell microgelelectrophoresis (Comet assay). Comet FISH was used to study the sensitivity of TP53-a crucial target gene for the transition of adenoma to carcinoma-towards HNE. Expression of glutathione S-transferases (GST), which deactivates HNE, was determined as GST activity and GSTP1 protein levels. LT97 cells were compared to primary human colon cells and to a differentiated clone of HT29. Karyotyping revealed that the LT97 cell line had a stable karyotype with only two clones, each containing a translocation t(7;17) and one aberrant chromosome 1. The Comet assay experiments showed that both HNE and H(2)O(2) were clearly genotoxic in the different human colon cells. HNE was more genotoxic in LT97 than in HT29clone19A and primary human colon cells. After HNE incubation, TP53 migrated more efficiently into the comet tail than the global DNA, which suggests a higher susceptibility of the TP53 gene to HNE. GST expression was significantly lower in LT97 than in HT29clone19A cells, which could explain the higher genotoxicity of HNE in the colon adenoma cells. In conclusion, the LT97 is a relevant model for studying genotoxicity of colon cancer risk factors since colon adenoma are common preneoplastic lesions occurring in advanced age.