Evaluación de la interacción de capecitabina con inhibidores de la bomba de protones en pacientes con cáncer de colon metastásico / Evaluation of the interaction of capecitabin with proton pump inhibitors in patients with metastatic colon cáncer

Objetivo: Evaluar el impacto clínico que la interacción de capecitabina con inhibidores de la bomba de protones (IBP) puede tener sobre la efectividad del tratamiento de mantenimiento en pacientes con cáncer de colon metastásico (CCm). Material y métodos: Estudio retrospectivo, observacional descriptivo que incluyó a todos los pacientes con CCm tratados con capecitabina sola o en combinación entre enero 2013-diciembre 2016. Los pacientes fueron divididos en dos grupos según si fueron o no tratados con IBP concomitantemente con capecitabina. Se evaluaron variables demográficas, farmacológicas y clínicas, siendo la supervivencia libre de progresión (SLP) la variable elegida para evaluar el impacto clínico de la interacción. Resultados: Se incluyeron 150 pacientes. De ellos, el 57,33% varones, media de edad 70,10±12,06 años; el 55,33% tuvieron un ECOG 1 y el 58,67% utilizaron IBP. Un 39,33% fueron tratados con capecitabina en monoterapia, 31,33% CapeOx, y 20% capecitabina+bevacizumab y 9,33% CapeOx+bevacizumab. El 53,33% tuvo un tratamiento basado en capecitabina en primera línea, la frecuencia de variaciones de tratamiento fue de 42,0% reducción de dosis, 38,0% retraso, y 12% interrupción tratamiento. El 78,0% presentó alguna toxicidad, destacando 34,67% diarrea y 30,0% (síndrome mano-pie). La SLP media fue de 6,69 vs 6,0 meses (HR=0,97; IC95% 0,68-1,39; p=0,87) en favor de los pacientes que no utilizaron IBP, aunque la relación fue no significativa. Conclusiones: En la población estudiada, los pacientes con CCm que recibieron tratamiento de mantenimiento basado en capecitabina y que utilizaron IBP simultáneamente, presentaron una tendencia no significativa a la disminución de la SLP. (AU)

Objective: To evaluate the clinical impact that the interaction of capecitabine with proton pump inhibitors (PPIs) may have on the effectiveness of maintenance treatment in patients with metastatic colon cancer (mCC). Material and methods: Retrospective, observational, descriptive study that included all patients with CCm treated with capecitabine alone or in combination between January 2013-December 2016. The patients were divided into two groups according to whether or not they were treated with PPIs concomitantly with capecitabine. Demographic, pharmacological and clinical variables were evaluated, with progression free survival (PFS) being the variable chosen to evaluate the clinical impact of interaction. Results:150 patients were included. Of them, 57.33% were men, mean age 70.10±12.06 years; 55.33% had an ECOG 1 and 58.67% used it in PPIs. 39.33% were treated with capecitabine in monotherapy, 31.33% CapeOx, and 20% capecitabine+bevacizumab and 9.33% CapeOx+bevacizumab. 53.33% had a first-line capecitabine-based treatment, the frequency of treatment variations was 42.0% dose reduction, 38.0% delay, and 12% treatment interruption. 78.0% presented any toxicity, (highlighting 34.67% diarrhea and 30.0% hand-foot syndrome). The mean PFS was 6.69 vs 6.0 months (HR=0.97; 95% CI 0.68-1.39; p=0.87) in favor of patients who did not use IBP, although the relationship was not significant. Conclusions: In the population studied, patients with mCC who received maintenance treatment based on capecitabine and who used PPIs simultaneously, showed a non-significant trend towards a decrease in PFS. (AU)

Transcriptional regulation of the human sodium/iodide symporter gene by Pax8 and TTF-1.

The regulation of the human Na(+)/I(-) symporter (NIS) gene is of considerable interest for both the diagnosis and therapy of thyroid pathologies. We investigated the influence of the thyroid-specific transcription factors TTF-1 and Pax8 on the NIS promoter and its 5'-flanking sequence. Reporter genes containing the corresponding genomic fragments coupled to a luciferase reporter gene were cotransfected with expression vectors carrying the the cDNA's for TTF-1 and Pax8. Transient transfection assays were performed in HeLa and COS-7 cells, which do not express endogenously these transcription factors. The experiments showed, that TTF-1 had no influence on the NIS promoter. Pax8, on the other hand, had a moderate stimulating effect (threefold) on the proximal NIS promoter. ABCD assays indicated an interaction of in vitro-translated Pax8 with the NIS promoter. However, DNase I footprinting experiments with bacterially expressed Pax8 were negative, suggesting an indirect mode of action with the participation of other proteins. A putative NIS upstream enhancer (NUE) 9000 bp upstream of the NIS gene, which was cloned based on its sequence homology to the rat NUE, was not transactivated by either Pax8 or TTF-1. The present data demonstrate, that the combination of Pax8 and TTF-1 is less important for NIS gene transcription than for other thyroid-specific genes. This is presumably related to the fact, that NIS is expressed also in other tissues such as mammary and salivary gland.

Thyroid transcription factor 1 and Pax8 synergistically activate the promoter of the human thyroglobulin gene.

Thyroglobulin (Tg) is an essential thyroid-specific protein, which serves as the matrix for thyroid hormone biosynthesis. To obtain new insights in the regulation of Tg gene expression, we investigated the interaction of the human Tg promoter with the thyroid-specific transcription factors TTF-1 and Pax8. A reporter gene, containing a 202 bp fragment from the human Tg 5'-flanking region including the promoter sequence and the transcriptional start site, and expression vectors containing the cDNAs for human TTF-1 and Pax8 were used in cotransfection experiments, in the non-thyroidal cell lines COS-7 and HeLa. Pax8 increased the specific transcriptional activity of the Tg promoter about threefold, whereas cotransfection with the homeodomain-containing protein TTF-1 stimulated promoter activity from six- to tenfold. The simultaneous expression of both factors stimulated the Tg promoter activity in a multiplicative manner up to 25-fold. TTF-1 binding sites could be localized precisely by lectron mobility shift assay. The two binding elements corresponded to sites A and C in the rat Tg promoter. Site-directed mutagenesis of three nucleotides in each binding element inhibited binding of TTF-1 to the two oligonucleotides. In cotransfection experiments, the mutant site C decreased TTF-1 transactivation to 26% of the wild-type, whereas an additional mutation in the site A reduced this value to almost zero, thus proving the physiological relevance of these sites. The present results demonstrate that the activity of the human Tg promoter is closely dependent on the function of TTF-1 and Pax8, opening the field for further investigations of pathological alterations of Tg gene expression.

Cloning and characterization of repressory and stimulatory DNA sequences upstream the Na/I-symporter gene promoter.

To investigate the existence of potential enhancer or silencer elements in the 5'-flanking region of the human Na+/I-symporter (NIS) gene, we cloned 2,512 bp of genomic DNA further upstream of the previously defined proximal promoter. When tested in reporter gene assays, this sequence had no transcriptional activity per se, but was able to repress the activity of the heterologous SV40 promoter. Conversely, when fused to the homologous NIS gene promoter and thus comprising 3,800 bp 5'-flanking region, the transcription of the proximal NIS promoter was stimulated in the human cell lines FTC-133 (from thyroid) and HeLa, but inhibited in the rat thyroid cell line FRTL-5. This might be due to differences between the upstream regions of the rat and human NIS gene. Comparative analysis with standard promoters (SV40) led to the conclusion that the 5'-flanking region of the human NIS gene also exhibited transcriptional activity in non-thyroid cells. Thyroid-stimulating hormone (TSH) had a moderately stimulating effect on the full length NIS reporter gene construct in FRTL-5 cells. This stimulation is presumably mediated by a putative cAMP responsive element found in the first half of the cloned sequence.

Cloning of a functional promoter of the human sodium/iodide-symporter gene.

We have cloned and sequenced genomic DNA from a human library extending 1300 bp upstream the 5'-untranslated sequence of the cDNA coding for the sodium/iodide symporter. In transient transfection assays this sequence exhibited promoter activity, which could be confined to nucleotides -443 to -395 relative to the ATG start codon. This minimal promoter, including a putative GC- and TATA- box, was preferentially activated in the rat thyroid cell line FRTL-5, but was also active in non-thyroidal cells, such as COS-7 and Chinese-hamster ovary, albeit to a markedly lower extent.