GSK2606414 Sensitizes ABCG2-Overexpressing Multidrug-Resistant Colorectal Cancer Cells to Chemotherapeutic Drugs.

Colorectal cancer is a common malignant tumor. A major factor in the high mortality rate of colorectal cancer is the emergence of multidrug resistance (MDR). Overexpression of the ABCG2 gene in cancer cells directly leads to MDR. Finding new inhibitors of ABCG2 may be an effective way to overcome drug resistance. We found that the compound GSK2606414 enhanced the sensitivity of the ABCG2 substrate to the chemotherapeutic drugs mitoxantrone and doxorubicin in ABCG2-overexpressing multidrug-resistant colorectal cancer cells by increasing their intracellular accumulation without affecting the protein expression of ABCG2. Molecular docking experiments predicted that GSK2606414 could stably bind in the drug-binding pocket of ABCG2. In conclusion, GSK2606414 can sensitize ABCG2-overexpressed multidrug-resistant colorectal cancer cells to chemotherapy drugs and can be used as a potential inhibitor of ABCG2.

Inhibiting the Activity of ABCG2 by KU55933 in Colorectal Cancer.

BACKGROUND: Therapeutic resistance is a frequent problem of cancer treatment and a leading cause of mortality in patients with metastatic colorectal cancer (CRC). Recent insight into the mechanisms that confer multidrug resistance has elucidated that the ATP-binding cassette (ABC) superfamily G member 2 (ABCG2) assists cancer cells in escaping therapeutic stress caused by toxic chemotherapy. Therefore, it is necessary to develop ABCG2 inhibitors. OBJECTIVES: In the present study, we investigated the inhibitory effect of KU55933 on ABCG2 in CRC. METHODS: The cytotoxicity assay and drug accumulation assay were used to examine the inhibitory effect of KU55933 on ABCG2. The protein expressions were detected by Western blot assay. The docking assay was performed to predict the binding site and intermolecular interactions between KU55933 and ABCG2. RESULTS: KU55933 was more potent than the known ABCG2 inhibitor fumitremorgin C to enhance the sensitivity of mitoxantrone and doxorubicin and the intracellular accumulation of mitoxantrone, doxorubicin and rhodamine 123 inside CRC cells with ABCG2 overexpression. Moreover, KU55933 did not affect the protein level of ABCG2. Furthermore, the docking data showed that KU55933 was tightly located in the drug-binding pocket of ABCG2. CONCLUSION: In summary, our data presented that KU55933 could effectively inhibit the drug pump activity of ABCG2 in colorectal cancer, which is further supported by the predicted model that showed the hydrophobic interactions of KU55933 within the drug-binding pocket of ABCG2. KU55933 can potently inhibit the activity of ABCG2 in CRC.

Molecular Investigation of Zoonotic Intestinal Protozoa in Pet Dogs and Cats in Yunnan Province, Southwestern China.

Giardia duodenalis, Enterocytozoon bieneusi and Cryptosporidium spp. are common enteric pathogens that reside in the intestines of humans and animals. These pathogens have a broad host range and worldwide distribution, but are mostly known for their ability to cause diarrhea. However, very limited information on prevalence and genotypes of G. duodenalis, E. bieneusi and Cryptosporidium spp. in pet dogs and cats are available in China. In the present study, a total of 433 fecal samples were collected from 262 pet dogs and 171 pet cats in Yunnan province, southwestern China, and the prevalence and the genotypes of G. duodenalis, E. bieneusi and Cryptosporidium spp. were investigated by nested PCR amplification and DNA sequencing. The prevalence of G. duodenalis, E. bieneusi and Cryptosporidium spp. was 13.7% (36/262), 8.0% (21/262), and 4.6% (12/262) in dogs, and 1.2% (2/171), 2.3% (4/171) and 0.6% (1/171) in cats, respectively. The different living conditions of dogs is a risk factor that is related with the prevalence of G. duodenalis and E. bieneusi (p < 0.05). However, there were no statistically significant difference in prevalence of three pathogens in cats. DNA sequencing and analyses showed that four E. bieneusi genotypes (PtEb IX, CD9, DgEb I and DgEb II), one Cryptosporidium spp. (C. canis) and two G. duodenalis assemblages (C and D) were identified in dogs; two E. bieneusi genotypes (Type IV and CtEb I), one Cryptosporidium spp. (C. felis) and one G. duodenalis assemblage (F) were identified in cats. Three novel E. bieneusi genotypes (DgEb I, DgEb II and CtEb I) were identified, and the human-pathogenic genotypes/species Type IV C. canis and C. felis were also observed in this study, indicating a potential zoonotic threat of pet dogs and cats. Our results revealed the prevalence and genetic diversity of G. duodenalis, E. bieneusi and Cryptosporidium spp. infection in pet dogs and cats in Yunnan province, southwestern China, and suggested the potential threat of pet dogs and cats to public health.

AZ32 Reverses ABCG2-Mediated Multidrug Resistance in Colorectal Cancer.

Colorectal cancer is a common malignancy with the third highest incidence and second highest mortality rate among all cancers in the world. Chemotherapy resistance in colorectal cancer is an essential factor leading to the high mortality rate. The ATP-binding cassette (ABC) superfamily G member 2 (ABCG2) confers multidrug resistance (MDR) to a range of chemotherapeutic agents by decreasing their intracellular content. The development of novel ABCG2 inhibitors has emerged as a tractable strategy to circumvent drug resistance. In this study, an ABCG2-knockout colorectal cancer cell line was established to assist inhibitor screening. Additionally, we found that ataxia-telangiectasia mutated (ATM) kinase inhibitor AZ32 could sensitize ABCG2-overexpressing colorectal cancer cells to ABCG2 substrate chemotherapeutic drugs mitoxantrone and doxorubicin by retaining them inside cells. Western blot assay showed that AZ32 did not alter the expression of ABCG2. Moreover, molecule docking analysis predicted that AZ32 stably located in the transmembrane domain of ABCG2. In conclusion, our result demonstrated that AZ32 could potently reverse ABCG2-mediated MDR in colorectal cancer.

Copper-modified palygorskite is effective in preventing and treating diarrhea caused by Salmonella typhimurium.

The aim of this research was to develop effective alternative therapies to reduce antibiotic use in animal agriculture. In this study, the efficacy of copper-modified palygorskite (CM-Pal) in preventing diarrhea caused by Salmonella was specifically examined both in vitro and in vivo. The CM-Pal was prepared with palygorskite (Pal) and copper nitrate. The antibacterial activity of the CM-Pal was detected by comparing the differences in cell numbers on plate count agar before and after adding the CM-Pal to Salmonella typhimurium cultures. Seventy ICR mice were then allocated into seven groups. Five groups (the treatment groups) were infected with S. typhimurium by intraperitoneal (i.p.) injection and were given Pal, CM-Pal, montmorillonite powder, gentamicin, and physiological saline, respectively. One group (the prevention group) was given CM-Pal before infection with S. typhimurium. Another group (the uninfected group) was not infected with S. typhimurium. The effects of Pal, CM-Pal, montmorillonite powder, and gentamicin on the treatment or prevention of diarrhea in the mice were examined by stool studies, fecal scoring, and assessment of growth performance and villus height. The CM-Pal had satisfactory anti-bacterial properties in vitro: the antibacterial rate was 100% after 2 h incubation with S. typhimurium NJS1 cultures (1×106 colony-forming units (CFU)/ml). In the in vivo experiment, the CM-Pal exerted superior effects in the treatment and prevention of diarrhea in mice compared with Pal, montmorillonite powder, and gentamicin. In the CM-Pal group, no mice showed signs of diarrhea at 24 h post infection (p.i.), and all mice fully recovered from infection. However, the Pal group, montmorillonite group, and gentamicin group only recovered after 48, 48, and 96 h, respectively. The villus height level in the CM-Pal treatment group recovered at 3 d p.i. However, the recovery time of the other groups was longer (at least 5 d). The CM-Pal prevention group had a better effect on weight gain than the other groups. This study suggested that CM-Pal may be an effective alternative to conventional antibiotics for the treatment and prevention of animal diarrhea caused by Salmonella.

Canine Babesiosis in China Caused by Babesia gibsoni: A Molecular Approach.

BACKGROUND: To provide a point of reference to study the epidemiology and clinical expression of canine babesiosis in China. METHODS: A total of 30 dogs infected with canine babesiosis were evaluated by mean of clinical history, physical examination, hematological, restriction fragment length polymorphism of PCR products (PCR-RFLP) and sequencing analysis. RESULT: The most prevalent clinical abnormalities were lethargy (100%), anorexia (100%), pale or icteric mucous membranes (80%), fever (70%) and dark urine (70%). Hematology parameters revealed that anemia and thrombocytopenia were the major abnormalities in blood of dogs infected with canine babesia. The results of PCR-RFLP and sequencing analysis indicated that B. gibsoni was the main species responsible for canine babesiosis cases at the time of the study in Nanjing, China. CONCLUSIONS: The results provide valuable information for better understanding of the epidemiology of canine babesiosis in China.