ABSTRACT Blue eggshells have become economically valuable due to their higher popularity among consumers when compared with eggs of other colors, particularly in East Asia. However, eggshell colors vary widely and gradually become lighter with the increase of age. Therefore, to determine the association between DNA methylation and gene expression on the molecular mechanism of eggshell color variation in Xuefeng Black-bone chickens, we collected the shell glands from chickens that produced dark blue eggshells and light blue eggshells, respectively, and performed whole genome bisulfite sequencing (WGBS) and RNA sequencing (RNA-Seq) on them. The results showed that in the context of CG, DNA methylation levels were the highest compared to CHG and CHH contexts, and were negatively correlated with gene expression levels in three different gene regions in all samples, while there was no significant correlation in the contexts of CHG and CHH. Furthermore, when disregarding the location of coding genes, a total of 55 genes will show differences not only in expression levels but also in DNA methylation levels, and among the majority of differential expression genes (n=50), the DNA methylation levels in the gene body region were the highest. GO analysis and KEGG pathway analysis were performed in these genes and the results showed that the genes NR1H4 and HEPHL1, ABCA4 and ABCA12, and the pathways, cell adhesion molecular, ABC transporters, ECM-receptor interaction, and neuroactive ligand-receptor interaction, may affect the color variation of the blue eggshell of Xuefeng Black-bone chickens.

Cetuximab is widely used in patients with metastatic colon cancer expressing wildtype KRAS. However, acquired drug resistance limits its clinical efficacy. Exosomes are nanosized vesicles secreted by various cell types. Tumor cell-derived exosomes participate in many biological processes, including tumor invasion, metastasis, and drug resistance. In this study, exosomes derived from cetuximab-resistant RKO colon cancer cells induced cetuximab resistance in cetuximab-sensitive Caco-2 cells. Meanwhile, exosomes from RKO and Caco-2 cells showed different levels of phosphatase and tensin homolog (PTEN) and phosphor-Akt. Furthermore, reduced PTEN and increased phosphorylated Akt levels were found in Caco-2 cells after exposure to RKO cell-derived exosomes. Moreover, an Akt inhibitor prevented RKO cell-derived exosome-induced drug resistance in Caco-2 cells. These findings provide novel evidence that exosomes derived from cetuximab-resistant cells could induce cetuximab resistance in cetuximab-sensitive cells, by downregulating PTEN and increasing phosphorylated Akt levels.

The receptor activator of nuclear factor κB ligand (RANKL)/RANK pathway plays an important role in the prognosis of several solid tumor types, but its role in gastric cancer prognosis has been poorly characterized. A total of 116 gastric cancer patients who underwent surgical resection were enrolled in this study. Expressions of RANKL and RANK in gastric cancer tissues were detected using immunohistochemical staining. Thirty-eight patients (33%) showed a high level of RANKL expression and 61 patients (53%) showed a high level of RANK expression. There was a positive correlation between expressions of RANKL and RANK (P=0.014, r=0.221). A high level of RANKL expression indicated shorter overall survival (OS) (P=0.008), and was associated with a higher pathological tumor/lymph node/metastasis (pTNM) stage (P=0.035), while no significant correlation was detected between RANK expression and clinicopathological parameters. RANKL also predicted poor prognosis in patients with high RANK expression (P=0.008) and Bormann's type III/IV (P=0.002). Furthermore, RANKL expression correlated with pTNM stage according to high RANK expression (P=0.009), while no significance was found in patients with low RANK expression (P=1.000). Together, our results revealed that high expression of RANKL could predict worse outcomes in gastric cancer especially combined with RANK detection, and thereby this pathway could be a useful prognostic indicator of gastric cancer.