The binding affinity-dependent inhibition of cell growth and viability by DNA sulfur-binding domains.

Increasing evidence suggests that DNA phosphorothioate (PT) modification serves several purposes in the bacterial host, and some restriction enzymes specifically target PT-DNA. PT-dependent restriction enzymes (PDREs) bind PT-DNA through their DNA sulfur binding domain (SBD) with dissociation constants (KD ) of 5 nM~1 µM. Here, we report that SprMcrA, a PDRE, failed to dissociate from PT-DNA after cleavage due to high binding affinity, resulting in low DNA cleavage efficiency. Expression of SBDs in Escherichia coli cells with PT modification induced a drastic loss of cell viability at 25°C when both DNA strands of a PT site were bound, with one SBD on each DNA strand. However, at this temperature, SBD binding to only one PT DNA strand elicited a severe growth lag rather than lethality. This cell growth inhibition phenotype was alleviated by raising the growth temperature. An in vitro assay mimicking DNA replication and RNA transcription demonstrated that the bound SBD hindered the synthesis of new DNA and RNA when using PT-DNA as the template. Our findings suggest that DNA modification-targeting proteins might regulate cellular processes involved in DNA metabolism in addition to being components of restriction-modification systems and epigenetic readers.

Role of the CXCR6/CXCL16 axis in autoimmune diseases.

The C-X-C motif ligand 16, or CXCL16, is a chemokine that belongs to the ELR - CXC subfamily. Its function is to bind to the chemokine receptor CXCR6, which is a G protein-coupled receptor with 7 transmembrane domains. The CXCR6/CXCL16 axis has been linked to the development of numerous autoimmune diseases and is connected to clinical parameters that reflect disease severity, activity, and prognosis in conditions such as multiple sclerosis, autoimmune hepatitis, rheumatoid arthritis, Crohn's disease, and psoriasis. CXCL16 is expressed in various immune cells, such as dendritic cells, monocytes, macrophages, and B cells. During autoimmune diseases, CXCL16 can facilitate the adhesion of immune cells like monocytes, T cells, NKT cells, and others to endothelial cells and dendritic cells. Additionally, sCXCL16 can regulate the migration of CXCR6-expressing leukocytes, which includes CD8+ T cells, CD4+ T cells, NK cells, constant natural killer T cells, plasma cells, and monocytes. Further investigation is required to comprehend the intricate interactions between chemokines and the pathogenesis of autoimmune diseases. It remains to be seen whether the CXCR6/CXCL16 axis represents a new target for the treatment of these conditions.

Low-dose of magnesium sulfate solution was not inferior to standard regime of polyethylene glycol for bowel preparation in elderly patients: a randomized, controlled study.

BACKGROUND: Large polyethylene glycol (PEG) is a standard regimen for bowel preparation. However, elderly patients suffered from adverse events. This study was to compare the efficacy and safety of oral magnesium sulfate solution (MSS) vs standard PEG in elderly patients undergoing colonoscopy. METHODS: Elderly patients aged 60-90 years, from two endoscopic centers, were enrolled in China. Patients were randomized to take a low dose of MSS or a standard PEG regime in a split-dose regime. The primary endpoint was the proportion of patients with adequate bowel preparation, which was defined as the total Boston Bowel Preparation Scale (BBPS) ≥6 and each segmental BBPS was ≥2. Secondary outcomes included adenoma detection rate (ADR), safety, adverse events, cecal intubation rate, willingness to repeat BP, and so on. RESULTS: 1174 elderly patients were randomly allocated to the MSS group (n = 588) or the standard group (n = 586). Adequate BP was achieved in 94.0% of patients in the MSS group and 92.5% in the control (p = .287). ADR was also comparable between the two groups (43.0% and 39.9%, p = .282). Compared with the standard group, MSS group reported less abdominal discomfort (1.7% vs 6.0%), less nausea (13.6% vs 21.0%) and vomiting (1.2% vs 4.2%). The change in serum potassium levels after preparation in the standard group was significantly lower than that in the MSS group (-0.19 ± 0.08 vs -0.41 ± 0.11, p = .037). CONCLUSIONS: Low dose of MSS was not inferior to the standard PEG regime in terms of bowel preparation quality for elderly patients. Low-dose MSS offered fewer adverse events and better tolerability. It is a preferable choice for the elderly to undergo bowel preparation for colonoscopy. CLINICAL TRIAL REGISTRATION NUMBER: NCT04948567.

A Zero-Valent Sulfur Transporter Helps Podophyllotoxin Uptake into Bacterial Cells in the Presence of CTAB.

Podophyllotoxin (PTOX) is naturally produced by the plant Podophyllum species. Some of its derivatives are anticancer drugs, which are produced mainly by using chemical semi-synthesis methods. Recombinant bacteria have great potential in large-scale production of the derivatives of PTOX. In addition to introducing the correct enzymes, the transportation of PTOX into the cells is an important factor, which limits its modification in the bacteria. Here, we improved the cellular uptake of PTOX into Escherichia coli with the help of the zero-valent sulfur transporter YedE1E2 in the presence of cetyltrimethylammonium bromide (CTAB). CTAB promoted the uptake of PTOX, but induced the production of reactive oxygen species. A protein complex (YedE1E2) of YedE1 and YedE2 enabled E. coli cells to resist CTAB by reducing reactive oxygen species, and YedE1E2 was a hypothetical transporter. Further investigation showed that YedE1E2 facilitated the uptake of extracellular zero-valent sulfur across the cytoplasmic membrane and the formation of glutathione persulfide (GSSH) inside the cells. The increased GSSH minimized oxidative stress. Our results indicate that YedE1E2 is a zero-valent sulfur transporter and it also facilitates CTAB-assisted uptake of PTOX by recombinant bacteria.

Gastroscopic results for the asymptomatic, average-risk population in Northern China: a cross-sectional study of 60,519 adults.

BACKGROUND: Studies on average-risk individuals undergoing gastroscopy screening in China are scarce. OBJECTIVE: To determine and compare the prevalence of lesions found by gastroscopy and the association between sex, age, Helicobacter pylori infection and gastric premalignant lesions. METHODS: Gastroscopy results were analysed for 60,519 individuals enrolled from January 2013 to December 2019. RESULTS: The median age was 49.84 years (SD, 9.47 years) for women and 48.90 years (SD, 8.82 years) for men, and the ratio of females to males was 35.10% (n = 21,240) to 64.90% (n = 39,279). The most common lesions detected by endoscopy were chronic gastritis, reflux oesophagitis, duodenitis and gastric polyps, detected in 24.48%, 10.28%, 3.96% and 3.61%, respectively. Oesophageal cancer and gastric cancer were detected in 0.33% and 0.47% of patients, respectively. The prevalence of chronic gastritis increased with age and was higher in males than in females (26.47% [n = 10396] versus 20.80% [n = 4417], p < .001). The prevalence of gastric ulcers was highest in the elderly group, and the H. pylori infection rate of gastric ulcer patients was 47.28%. The prevalence of gastric polyps was higher in females than in males (5.47% [n = 1161] versus 2.61% [n = 1024], p < .001), and the H. pylori infection rate in inflammatory polyp patients was higher than that in fundic gland polyp patients (28.32% [n = 442] versus 7.29% [n = 29], p < .001). CONCLUSION: The prevalence of upper gastrointestinal endoscopic lesions is high in the asymptomatic population undergoing physical examination and is associated with sex, age, and H. pylori infection.

MicroRNA-31 inhibits tumor invasion and metastasis by targeting RhoA in human gastric cancer.

Previous studies have shown that microRNA-31 (miR-31) functions as a tumor-suppressor in various types of cancer. In the present study we found that miR-31 was significantly downregulated in gastric cancer (GC) as determined by microRNA (miRNA) array screening analysis. Although aberrant expression of miR-31 has been found in different types of cancer, its pathophysiological effect and role in tumorigenesis still remain to be elucidated. In the present study, we detected miR-31 expression in both metastatic GC cell lines and tissues that are potentially highly metastatic by real-time polymerase chain reaction (PCR). Transwell and scratch healing assays were conducted to examine whether the ectopic expression of miR-31 could modify the invasion and migration abilities of GC cells in vitro. We found that miR-31 inhibited GC metastasis in a nude mouse xenograft model of GC. Luciferase reporter assays demonstrated that miR-31 could directly bind to the 3' untranslated region of RhoA and downregulate the expression of RhoA. Significant downregulation of miR-31 in 78 GC tissues and four GC cell lines was examined by real-time reverse transcription-PCR. Moreover, the decreased expression of miR-31 was demonstrated to be associated with lymph node metastasis, poor pT and pN stage, and invasion ability into lymphatic vessels as determined by the Mann-Whitney U test. We also found that miR-31 could inhibit cell invasion and migration abilities in vitro using the Transwell and scratch healing assays in BGC-823, SGC-7901, MGC-803 as well as AGS cells. Experiments in a nude mouse model revealed that miR-31 suppressed tumorigenicity in vivo. The luciferase activity assay and western blotting indicated that RhoA was the potential target of miR-31 in GC cells. Collectively, our results provide important evidence that the downregulation of miR-31 inhibited the invasion and migration abilities of GC cells through direct targeting of the tumor metastasis­associated gene, RhoA. These findings suggest that miR-31 may be a promising therapeutic candidate in the treatment of GC metastasis.

S100P predicts prognosis and drug resistance in gastric cancer.

PURPOSE: S100P has been shown to participate in processes of various human malignancies. In this study, we analyzed the tissue expression of S100P in gastric cancer and evaluated its significance. METHODS: We determined the S100P expression in 156 gastric cancer patients by quantitative RT-PCR. Tumor characteristics and overall survival (OS) for each patient were examined. In vitro experiments were conducted to examine whether ectopic expression of S100P modifies the proliferation and drug resistance of gastric cancer cells. RESULTS: Higher expression of S100P occurred in human gastric cancer tissues in comparison with normal controls. Highly expressed S100P in gastric cancer was correlated with TNM stage and prognosis. The 5-year survival rate was significantly lower in patients with high levels of S100P expression than in patients with low levels of expression. Ectopic expression of S100P was associated with an increase in tumor cell proliferation and drug resistance. CONCLUSION: The expression of S100P in human gastric cancer tissues was upregulated in comparison with normal controls. By establishing an association between S100P expression and shortened OS, increase in proliferation and drug resistance, this study indicates that S100P may be a useful prognostic marker for gastric cancer patients.

Inhibition of PI3K/Akt partially leads to the inhibition of PrP(C)-induced drug resistance in gastric cancer cells.

Cellular prion protein (PrP(C)), a glycosyl-phosphatidylinositol-anchored membrane protein with unclear physiological function, was previous found to be upregulated in adriamycin (ADR)-resistant gastric carcinoma cell line SGC7901/ADR compared to its parental cell line SGC7901. Overexpression of PrP(C) in gastric cancer has certain effects on drug accumulation through upregulation of P-glycoprotein (P-gp), which is suggested to play an important role in determining the sensitivity of tumor cells to chemotherapy and is linked to activation of the phosphatidylinositol-3-kinase/Akt (PI3K/Akt) pathway. In the present study, we further investigate the role of the PI3K/Akt pathway in PrP(C)-induced multidrug-resistance (MDR) in gastric cancer. Immunohistochemistry and confocal microscope detection suggest a positive correlation between PrP(C) and phosphorylated Akt (p-Akt) expression in gastric cancer. Using established stable PrP(C) transfectant cell lines, we demonstrated that the level of p-Akt was increased in PrP(C)-transfected cells. Inhibition of PrP(C) expression by RNA interference resulted in decreased p-Akt expression. Inhibition of the PI3K/Akt pathway by one of its specific inhibitors, LY294002, or by Akt small interfering RNA (siRNA) resulted in decreased multidrug resistance of SGC7901 cells, partly through downregulation of P-gp induced by PrP(C). Taken together, our results suggest that PrP(C)-induced MDR in gastric cancer is associated with activation of the PI3K/Akt pathway. Inhibition of PI3K/Akt by LY2940002 or Akt siRNA leads to inhibition of PrP(C)-induced drug resistance and P-gp upregulation in gastric cancer cells, indicating a possible novel mechanism by which PrP(C) regulates gastric cancer cell survival.

[MDR-reversing effect of short peptide binding specifically to multidrug-resistant gastric cancer cells].

OBJECTIVE: To investigate the binding effect of the short peptide SY1 to the multidrug-resistant gastric cancer cell line SGC7901/VCR cells and its reversing effect on those cancer cells. METHODS: The cultured cells were divided into two groups named SGC7901 and SGC7901/VCR. The SGC7901/VCR group was co-cultured with vincristine (VCR). SY1 was obtained from cyclic 7-mer peptide library by differential screening. Immunofluorescence technique was used to detect the capacity of SY1-containing positive phage specifically binding to SGC7901/VCR cells, compared with that of the negative phage and unrelated phage. MTT assay in vitro was performed to analyze the alteration of drug resistance of SGC7901/ VCR cells, using the positive phages and the chemically synthesized SY1 peptide. Flow cytometry assay was performed to detect the accumulation and retention of adriamycin (ADM) in the SGC7901/VCR cells. RESULTS: Immunofluorescence analysis showed that the SY1-containing positive phages could bind to the SGC7901/VCR cell surface but not to its parent cell line SGC7901 cells. The unrelated phage and negative phage did not bind to SGC7901/VCR cells. These results indicated that SY1 could specifically bind to SGC7901/VCR cells. MTT assay in vitro showed that the survival rate of SGC7901/VCR cells was reduced considerably by the positive phages and the chemically synthesized SY1 peptide (P <0. 05), indicating that SY1 enhanced the sensitivity of SGC7901/VCR cells to chemotherapeutic drug VCR. Flow-cytometric detection showed that SY1 enhanced the accumulation of ADM in the SGC7901/VCR cells, compared with that of the negative phages and the unrelated phages (P <0.05). CONCLUSION: SY1 not only is able to bind to SGC7901/VCR cells specifically, but also can partly reverse the resistance of SGC7901/VCR cell line to chemotherapeutic drug VCR. Those findings might be important to open a new approach to reverse the gastric cancer MDR.

Hypoxia induced overexpression of PrP(C) in gastric cancer cell lines.

Cellular prion protein (PrP(C)), a copper-binding glycosyl-phosphatidylinositol (GPI)-anchored membrane protein that is expressed predominantly in neurons can be induced in ischemia/hypoxic brain tissues. It was also found to be overexpressed and conferred multidrug resistance, promoting cancer metastasis and inhibiting apoptosis in gastric cancer in our lab. In solid tumors, hypoxia can promote malignant progression and confer resistance to chemotherapy by altering gene expression. In present study, we investigated the molecular mechanisms and signaling pathway involved in the induction of the PrP(C) gene by hypoxia in cancer cell lines. PrP(C) was detected to be upregulated in several cancer cell lines at both mRNA and protein level, and then found to be induced by hypoxia in a time-dependent manner. After hypoxia treatment, gastric cancer MKN28 cells transfected with luciferase reporter constructs of the human PrP(C) promoter, which contained HSE, expressed higher luciferase activities (4.3-fold) than those cells transfected with the constructs containing no HSE. In addition, the upregulation of PrP(C) was reduced by MERK/ERK inhibitor (PD98059). siRNA knockdown of PrP(C) could make the cells more sensitive to hypoxia induced drug sensitivity. In conclusion, from these findings, we can propose that some transcriptional factors phosphorylated by ERK1/2, could in turn interact with HSE in the promoter of PrP(C) resulting in upregulation of PrP(C) in gastric cancer cell line MKN28 during hypoxia. Downregulation of PrP(C) makes gastric cancer cells more sensitive to hypoxia induced drug sensitivity. However, other mechanisms might also be responsible for hypoxia induced overexpression of PrP(C) in gastric cancer.