Caco-2 cells, widely used to study carrier mediated uptake and efflux mechanisms, are known to have different properties when cultured under different conditions. In this study, Caco-2 cells from 10 different laboratories were compared in terms of mRNA expression levels of 72 drug and nutrient transporters, and 17 other target genes, including drug metabolising enzymes, using real-time PCR. The rank order of the top five expressed genes was: HPT1>GLUT3>GLUT5>GST1A>OATP-B. Rank correlation showed that for most of the samples, the gene ranking was not significantly different. Functionality of transporters and the permeability of passive transport markers metoprolol (transcellular) and atenolol (paracellular) were also compared. MDR1 and PepT1 function was investigated using talinolol and Gly-Sar transport, respectively. Sulfobromophthalein (BSP) was used as a marker for MRP2 and OATP-B functionality. Atenolol permeability was more variable across laboratories than metoprolol permeability. Talinolol efflux was observed by all the laboratories, whereas only five laboratories observed significant apical uptake of Gly-Sar. Three laboratories observed significant efflux of BSP. MDR1 expression significantly correlated to the efflux ratio and net active efflux of talinolol. PepT1 mRNA levels showed significant correlation to the uptake ratio and net active uptake of Gly-Sar. MRP2 and OATP-B showed no correlation to BSP transport parameters. Heterogeneity in transporter activity may thus be due to differences in transporter expression as shown for PepT1 and MDR1 which in turn is determined by the culture conditions. Absolute expression of genes was variable indicating that small differences in culture conditions have a significant impact on gene expression, although the overall expression patterns were similar.
"Transport capacities of membrane transporters are generally evaluated by means of transport experiments using specific substrates and/or inhibitors of target transporters. Among the many transporters expressed in Caco-2 cells and intestine  ,m a j o r drug transporters in Caco-2 cells, such as MDR1, MRP2, BCRP, and PEPT1, have often been analyzed  . However, other transporters have not been well analyzed, and indeed, specific substrates , inhibitors or effective siRNA are often not available. "
"Although Caco-2 cells retain many morphological and functional properties of the enterocytes, such as the expression of specific transporters and polarity, the intestinal cell behavior in vivo might be highly different. In addition, permeability data obtained from the Caco-2 system can often vary between laboratories, even when standard protocols for transport studies are used (Englund et al., 2006; Hayeshi et al., 2008). Therefore, when not properly controlled, relative Food Research International 54 (2013) 132–138 Abbreviations: BHT, butylated hydroxytoluene; Isc, Short circuit current; MF, microfiltrated; OMWW, Olive Mill Waste Water; P app , apparent permeability coefficient; P app,tissue , the apparent permeability coefficient tissue; P app,total , apparent permeability coefficient total; PCO 2 , partial pressure of carbon dioxide; PO 2 , partial pressure of oxygen; "
[Show abstract][Hide abstract] ABSTRACT: The intestinal absorption of verbascoside (VB), a phenylpropanoid glycoside, extracted and purified from olive mill waste water (OMWW), was investigated using viable and healthy human colonic tissues, mounted in an Ussing chamber. Additionally, VB absorption and transport through the intestinal mucosa were quantified using permeability coefficients. VB absorption was time-dependent and varied in relation to the specific colonic segments considered. In particular, major uptake/absorption (0.50 μg/cm 2) occurred between 5 and 15 min in the proximal tract of the colon, followed by descending colon (0.38 μg/cm 2) between 30 and 60 min, and sigmoid–rectum colon (0.34 μg/cm 2) at 60 min. Overall, VB was absorbed rapidly, with an average uptake of 0.29 μg VB per cm 2 , corresponding to a total accumulation efficiency of ~0.12%. Moreover, the presence of the VB in the basolateral side supported the hypothesis of its bioavailability in the extent of 0.1%. In addition, the permeability coefficient calculation has contributed in a deeper understanding of VB absorption and transport across the human intestinal barrier and could be utilized for other polyphenols present in food and in dietary supplements.
Food Research International 11/2013; 54(1):132-138. DOI:10.1016/j.foodres.2013.06.017 · 2.82 Impact Factor
"a s i a n j o u r n a l o f p h a r m a c e u t i c a l s c i e n c e s 8 ( 2 0 1 3 ) 1 5 1 e1 5 8 expression of multiple transporters. The heterogeneity of Caco-2 cells can be caused by different origins, culture conditions and number of cell passages . Thus cells stably expressed drug transporters were constructed to study the transport characters. "
[Show abstract][Hide abstract] ABSTRACT: Most drug products on the global pharmaceutical market are administered orally. The absorption of oral drug in the intestine is an important factor to determine the drug bioavailability. There are many intestinal transporters expressed on the small intestine and the transporters can be classified into two major families, SLC family and ABC family. They mediate drug absorption, distribution, excretion and drug–drug interaction. Understanding the transport mechanism can improve the effectivity and safety of drug and guide clinical rational use of drugs. The roles of drug transporters can be assessed in vitro and in vivo, using techniques spanning from cellular expression systems to gene knockout animals. The purposes of this article were to introduce the main transporters in the intestinal tract, to explain the transport mechanism and to compare the limitations and applications of techniques used to evaluate interactions of drugs and transporters.
Asian Journal of Pharmaceutical Sciences 06/2013; 8(3):151–158. DOI:10.1016/j.ajps.2013.07.020
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