Bacterial infection promotes tumorigenesis of colorectal cancer via regulating CDC42 acetylation.

Increasing evidence highlights the role of bacteria in promoting tumorigenesis. The underlying mechanisms may be diverse and remain poorly understood. Here, we report that Salmonella infection leads to extensive de/acetylation changes in host cell proteins. The acetylation of mammalian cell division cycle 42 (CDC42), a member of the Rho family of GTPases involved in many crucial signaling pathways in cancer cells, is drastically reduced after bacterial infection. CDC42 is deacetylated by SIRT2 and acetylated by p300/CBP. Non-acetylated CDC42 at lysine 153 shows an impaired binding of its downstream effector PAK4 and an attenuated phosphorylation of p38 and JNK, consequently reduces cell apoptosis. The reduction in K153 acetylation also enhances the migration and invasion ability of colon cancer cells. The low level of K153 acetylation in patients with colorectal cancer (CRC) predicts a poor prognosis. Taken together, our findings suggest a new mechanism of bacterial infection-induced promotion of colorectal tumorigenesis by modulation of the CDC42-PAK axis through manipulation of CDC42 acetylation.

[Flow Cytometric Analysis of Genome Size in Atractylodes lancea].

OBJECTIVE: To develop a rapid analytical method for the determination of genome size of Atractylodes lancea by flow cytometry (FCM), and to estimate genome size of five typical plant types of cultivated Atractylodes lancea. METHODS: The fresh young leaves of Atractylodes lancea were used for the preparation of nuclear suspension with two-step protocol. After staining with propidium iodide, the mixture was analyzed by flow cytometry. Zea mays 'CE-777' or Vicafaba 'Inorce' was used for DNA reference standard. RESULTS: The flow cytometric method was developed after screening internal standard, optimizing sample preparation and FCM setups. The narrow leaf type of Atractylodes lancea got the biggest genome size, whereas the smallest one was fasciated stem type. It was suggested that parted leaf might be caused by genome size decrease. CONCLUSION: The methodology presented in this study is suitable for measuring the genome size of Atractylodes lancea. This study also provides useful information on population variation, evaluation of germplasm resources, and breeding of Atractylodes lancea.