BACKGROUND:Disruptor of telomeric silencing-1-like (DOT1L), a methyltransferase of H3K79, was observed to be amplified and overexpressed in certain malignancies. This work was aimed at investigating the differences in DOT1L expression and its regulatory mechanism in gastric cancer (GC) and healthy samples. METHODS:Immunohistochemistry was used to detect DOT1L levels in 101 cases of GC and marching adjacent normal tissues. DOT1L was inhibited by small interfering RNA (siRNA) and EPZ5676; a targeting drug. The ability of cells to proliferate were checked by cell counting kit-8 (CCK-8) and clone formation assays, with flow cytometry for observing the cell cycle. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot revealed the gene and protein profiles. Finally, the outcome of EPZ5676 administration was checked on a murine model. RESULTS:The expression of DOT1L is significantly increased in gastric malignant tumors that is related to the degree of differentiation, lymph node metastasis and TNM staging. DOT1L serves as an independent marker for the prognosis of overall survival (OS) with high levels implying worse prognosis. In addition, DOT1L regulates cyclin-dependent kinase (CDK) 4 (CDK4) and CDK6 through H3K79me2, which leads to a change in the cell cycle at G1, thereby affecting the proliferation of tumors in vitro and in vivo. CONCLUSIONS:This is a first clinical demonstration of the applicability of DOT1L overexpression in gastric tumors. The work is suggestive of altered proliferation of cells by DOT1L via regulating cyclins and H3K79 methylation. This indicates the role of DOT1L in the prognosis and possible medical intervention of GC.

Background It has been reported that age-associated cognitive decline (AACD) accelerated by maternal lipopolysaccharide (LPS) insult during late pregnancy can be transmitted to the second generation in a sex-specificity manner. In turn, recent studies indicated that glial cell line‐derived neurotrophic factor (GDNF) and its cognate receptor (GFRα1) are critical for normal cognitive function. Based on this evidence, we aimed to explore whether Gdnf-GFRα1 expression contributes to cognitive decline in the F1 and F2 generations of mouse dams exposed to lipopolysaccharide (LPS) during late gestation, and to evaluate also the potential interference effect of pro-inflammatory cytokines. Methods During gestational days 15–17, pregnant CD-1 mice (8–10 weeks old) received a daily intraperitoneal injection of LPS (50 μg/kg) or saline (control). In utero LPS-exposed F1 generation mice were selectively mated to produce F2 generation mice. In F1 and F2 mice aged 3 and 15 months, the Morris water maze (MWM) was used to evaluated the spatial learning and memory ability, the western blotting and RT-PCR were used for analyses of hippocampal Gdnf and GFRα1 expression, and ELISA was used to analyse IL-1β, IL-6 and TNF-α levels in serum. Results Middle-aged F1 offspring from LPS-treated mothers exhibited longer swimming latency and distance during the learning phase, lower percentage swimming time and distance in targe quadrant during memory phase, and lower hippocampal levels of Gdnf and GFRα1 gene products compared to age-matched controls. Similarly, the middle-aged F2 offspring from the Parents-LPS group had longer swimming latency and distance in the learning phase, and lower percentage swimming time and distance in memory phase than the F2-CON group. Moreover, the 3-month-old Parents-LPS and 15-month-old Parents- and Father-LPS groups had lower GDNF and GFRα1 protein and mRNAs levels compared to the age-matched F2-CON group. Furthermore, hippocampal levels of Gdnf and GFRα1 were correlated with impaired cognitive performance in the Morris water maze after controlling for circulating pro-inflammatory cytokine levels. Conclusions Our findings indicate that accelerated AACD by maternal LPS exposure can be transmitted across at least two generations through declined Gdnf and GFRα1 expression, mainly via paternal linage.

Mounting evidence indicates that histone modifications are involved in aging-associated cognitive decline (AACD) and can be transmitted to offspring over multiple generations under conditions of stress. Here, we investigated the effects of maternal sub-chronic inflammation caused by lipopolysaccharide (LPS) on AACD and histone modifications in the F1 and F2 generations of experimental mice as well as the potential sex specificity of intergenerational effects. In brief, F0-generation CD-1 dams were exposed to LPS (50 µg/kg) or saline (CON) during late pregnancy. Subsequently, F1 males and females (at 2 months-of-age) from the LPS treatment group were mated with non-littermates from the LPS group or wild-type mice to produce F2 generations of parental- (F2-LPS2), paternal- (F2M-LPS1) and maternal-origin (F2F-LPS1) mice. Then, CON-F1 males and females were mated with wild-type mice to generate F2 generations of paternal- (F2M-CON1) and maternal-origin (F2F-CON1). Next, we evaluated the cognitive ability and levels of hippocampal H4K12ac and H3K9me3 in the F1 and F2 offspring at 3- and 13 months-of-age. Overall, F1 male and female LPS groups presented with elevated corticosterone (P < 0.001, P = 0.036, P = 0.025, 0.012, respectively) and cytokine responses, poorer cognitive performance (all P < 0.05) and H3K9 hypermethylation and H4K12 hypoacetylation in the dorsal hippocampus (all P < 0.05); these issues were carried over to the F2 generation via the parents, predominantly in the paternal lineage. Moreover, the levels of H3K9me3 and H4K12ac were significant correlated with cognitive performance (all P < 0.05), regardless of whether inflammatory insults had been incurred directly or indirectly. These findings indicated that gestational inflammatory insults in the F0 generation accelerated AACD in the F2 generation, along with H3K9 hypermethylation and H4K12 hypoacetylation in the hippocampus, and that these issues were derived from the F1 parents, especially from the F1 fathers.