CircDDX17 reduces 5-fluorouracil resistance and hinders tumorigenesis in colorectal cancer by regulating miR-31-5p/KANK1 axis.

OBJECTIVE: Colorectal cancer (CRC) is one of the most common malignancies worldwide. Chemotherapy resistance is a considerable obstacle to CRC treatment. Circular RNAs (circRNAs) are involved in the pathogenesis of many cancers. This study aimed to investigate the role and molecular basis of DEAD-box helicase 17 circRNA (circDDX17) in 5-fluorouracil (5-Fu) sensitivity and CRC progression. MATERIALS AND METHODS: The levels of circDDX17, microRNA-31-5p (miR-31-5p) and kidney ankyrin repeat-containing protein 1 (KANK1) were detected by quantitative real-time PCR or western blot assay. Cell viability was assessed by Cell Counting Kit-8 (CCK-8) assay. Cell apoptosis rate was monitored by flow cytometry. Cell invasion capacity was evaluated by transwell assay. Western blot assay was conducted to measure the expression of matrix metallopeptidase 9 (MMP9) and E-cadherin. The interaction among circDDX17, miR-31-5p and KANK1 was indicated by bioinformatics analysis and dual-luciferase reporter assay. Xenograft assay was performed to analyze tumor growth and 5-Fu sensitivity in vivo. RESULTS: CircDDX17 and KANK1 were down-regulated, while miR-31-5p was upregulated in CRC tissues and cells. Upregulation of circDDX17 enhanced 5-Fu sensitivity and impeded CRC development. CircDDX17 inhibited 5-Fu resistance and CRC progression via sponging miR-31-5p. Besides, KANK1 depletion attenuated the effect of circDDX17 upregulation on chemosensitivity and CRC progression. CircDDX17 regulated KANK1 expression by binding to miR-31-5p. Moreover, circDDX17 overexpression blocked tumor growth and elevated 5-Fu sensitivity in vivo. CONCLUSIONS: Upregulation of circDDX17 strengthened chemosensitivity of CRC to 5-Fu and blocked CRC progression by regulating miR-31-5p/KANK1 axis, which might provide an effective treatment strategy for CRC patients.

The expression of osteopontin in breast cancer tissue and its relationship with p21ras and CD44V6 expression.

OBJECTIVE: This study aimed to investigate the expression of osteopontin (OPN), p2lras, and CD44V6 in breast cancer tissues, and to analyze the relationships between their expression and a patient's clinicopathological characteristics and five-year survival rate. MATERIALS AND METHODS: Streptavidin-peroxidase immunohistochemistry was used to detect the expression of OPN, p2lras, and CD44V6 in tissue samples from 96 breast cancer patients, and the multivariate Cox proportional hazards model (mCOX-PHM) was used to analyze the factors that affect prognosis. RESULTS: Among the 96 breast cancer patients studied, positive staining for OPN, CD44V6, and p21ras was observed in 54.2%, 58.3%, and 43.8% of samples, respectively. The expression of OPN and CD44V6 were positively correlated (r = 0.58), and the expression of OPN and p21ras were also positively correlated (r = 0.25). Coexpression OPN, CD44V6, and p21ras was negatively correlated with a patient's five-year survival rate (p < 0.05). Kaplan-Meier analysis indicated that a patient without OPN, CD44V6, or p21ras expression had an improved survival (p < 0.05). Results from the mCOX-PHM analysis indicated that CD44V6 expression, the degree of tumor differentiation, and lymph node metastasis were all independent factors that indicate prognosis. The combined detection of OPN, CD44V6, and p21ras could contribute to a more accurate assessment of the biological behavior of breast cancers, and could help to indicate the prognosis of breast cancer patients.

Characterization of lipase of Pseudomonas fluorescens 27 based on fatty acid profiles.

The objectives of this research were to isolate lipase from Pseudomonas fluorescens 27, to compare the purity of the partially purified lipase preparation with crude extract, and to determine if bands of lipase activity revealed by disc gel electrophoresis liberated different free fatty acids from milk fat. Lipases were isolated from a shaken skim milk culture of P. fluorescens 27 by using ion-exchange chromatography on DEAE cellulose (Whatman DE 32) and gel filtration on Sephadex G-150. The principal lipase-rich fractions from gel filtration represented 6.2% of total lipolytic activity. Disc gel electrophoresis of partially purified enzyme revealed two protein bands. These protein bands were cut from disc electrophoresis gels and used as an enzyme source for reaction with butter oil. Free fatty acids were isolated from the assay mixture, separated, and quantified by gas chromatography. Data from gas chromatographic analysis indicated that P. fluorescens 27 produces at least two different lipases.

Comparison of the heat resistance of bacterial lipases and proteases and the effect on ultra-high temperature milk quality.

Thirty-four of 49 isolates of psychrotrophic bacteria produced extracellular lipase or protease when grown in rehydrated nonfat dry milk. The cell-free crude preparation from 50% of these had either heat-resistant lipase or protease; in 30% both enzymes were heat resistant. Eight isolates were selected for further evaluation of effect on ultra-high temperature processed milk. Free fatty acids and free amino groups of milk precultured with the bacteria increased at different rates depending on the isolate. Partially purified lipase from one of these bacteria (Acinetobacter sp.) caused free fatty acids to increase following ultra-high temperature processing when the milk was stored at 10, 21, or 32 degrees C for 4 wk. The increase was temperature dependent. Lipase activity of .0012 units/ml added prior to processing caused significant increases in free fatty acid at 21 and 32 degrees C in 4 wk.