Identification of a NFκB Inhibition Site on the Proximal Promoter Region of Human Organic Anion Transporting Polypeptide 1A2 Coding Gene SLCO1A2

Genomewide association analysis on green tea chemoprevention of colorectal adenoma: the importance of SLCO1A2 variants

BACKGROUND

Green tea extract was tested for the secondary prevention of colorectal adenoma in the placebo-controlled MIRACLE trial. Genome-wide screening on adenoma recurrence was performed in n = 550 participants 3 years after randomization to green tea or placebo intake.

METHODS

Single Marker Analysis followed by regression analyses was calculated for all 700.078 markers assuming an additive genetic model and including all covariates from the main MIRACLE trial analysis. The outcome was an adenoma rate at 3-year follow-up colonoscopy comparing participants carrying a genetic variant versus wildtype.

RESULTS

The gene showing the strongest association with the outcome in both, SMA as well as regression analysis, was the organic anion transporter SLCO1A2. In the variant carriers, the adenoma frequency was 41.4% in the green tea group and 35.7% in the placebo group (RR 1.16 [0.81; 1.65] p = 0.61), whereas in the nonvariant carriers, the frequency of reoccurrence was 54.5% in the green tea group and 66.5% in the placebo group (RR 0.82 [0.69; 0.97], p = 0.03).

CONCLUSION

Individuals with genetic variants in the transporter SLCO1A2 may be protected against colon adenoma irrespective of the green tea intake. In nonvariant carriers of SLCO1A2, green tea was associated with a clear benefit in outcome (18% risk reduction).

The Induction of Drug Uptake Transporter Organic Anion Transporting Polypeptide 1A2 by Radiation Is Mediated by the Nonreceptor Tyrosine Kinase v-YES-1 Yamaguchi Sarcoma Viral Oncogene Homolog 1

Organic anion transporting polypeptides (OATP, gene symbol SLCO) are well-recognized key determinants for the absorption, distribution, and excretion of a wide spectrum of endogenous and exogenous compounds including many antineoplastic agents. It was therefore proposed as a potential drug target for cancer therapy. In our previous study, it was found that low-dose X-ray and carbon ion irradiation both upregulated the expression of OATP family member OATP1A2 and in turn, led to a more dramatic killing effect when cancer cells were cotreated with antitumor drugs such as methotrexate. In the present study, the underlying mechanism of the phenomenon was explored in breast cancer cell line MCF-7. It was found that the nonreceptor tyrosine kinase v-YES-1 Yamaguchi sarcoma viral oncogene homolog 1 (YES-1) was temporally coordinated with the change of OATP1A2 after irradiation. The overexpression of YES-1 significantly increased OATP1A2 both at the mRNA and protein level. The signal transducer and activator of transcription 3 (STAT3) pathway is likely the downstream target of YES-1 because phosphorylation and nuclear accumulation of STAT3 were both enhanced after overexpressing YES-1 in MCF-7 cells. Further investigation revealed that there are two possible binding sites of STAT3 localized at the upstream sequence of SLCO1A2, the encoding gene of OATP1A2. Electrophoretic mobility shift assay and chromatin immunoprecipitation analysis suggested that these two sites bound to STAT3 specifically and the overexpression of YES-1 significantly increased the association of the transcription factor with the putative binding sites. Finally, inhibition or knockdown of YES-1 attenuated the induction effect of radiation on the expression of OATP1A2. SIGNIFICANCE STATEMENT: The present study found that the effect of X-rays on v-YES-1 Yamaguchi sarcoma viral oncogene homolog 1 (YES-1) and organic anion transporting polypeptides (OATP)1A2 was temporally coordinated. YES-1 phosphorylates and increases the nuclear accumulation of signal transducer and activator of transcription 3, which in turn binds to the upstream regulatory sequences of SLCO1A2, the coding gene for OATP1A2. Hence, inhibitors of YES-1 may suppress the radiation induction effect on OATP1A2.

Drug Transporters in Xenobiotic Disposition and Pharmacokinetic Prediction

Drug transporters are widely expressed in organs and tissue barriers throughout human and animal bodies. Studies over the last two decades have identified various ATP-binding cassette and solute carrier transporters that play critical roles in the absorption, distribution, metabolism, and elimination of drugs and xenobiotics. This special section contains more than 20 original manuscripts and reviews that cover the most recent advances in the areas of drug transporter research, including the basic biology and function of transporters, expression of drug transporters in organ and tissue barriers, the mechanisms underlying regulation of transporter expression, transporter-mediated drug disposition in animal models, and the development and utilization of new technologies in drug transporter study, as well as pharmacokinetic modeling and simulation to assess transporter involvement in drug disposition and drug-drug interactions. We believe that the topics covered in this special section will advance our understanding of the roles of transporters in drug disposition, efficacy, and safety.