RESUMO
Protein kinase A (PKA)-induced estrogen receptor alpha (ERα) phosphorylation at serine residue 305 (ERαS305-P) can induce tamoxifen (TAM) resistance in breast cancer. How this phospho-modification affects ERα specificity and translates into TAM resistance is unclear. Here, we show that S305-P modification of ERα reprograms the receptor, redirecting it to new transcriptional start sites, thus modulating the transcriptome. By altering the chromatin-binding pattern, Ser305 phosphorylation of ERα translates into a 26-gene expression classifier that identifies breast cancer patients with a poor disease outcome after TAM treatment. MYC-target genes and networks were significantly enriched in this gene classifier that includes a number of selective targets for ERαS305-P. The enhanced expression of MYC increased cell proliferation in the presence of TAM. We demonstrate that activation of the PKA signaling pathway alters the transcriptome by redirecting ERα to new transcriptional start sites, resulting in altered transcription and TAM resistance.
Assuntos
Antineoplásicos Hormonais/farmacologia , Neoplasias da Mama/patologia , Resistencia a Medicamentos Antineoplásicos/genética , Antagonistas de Estrogênios/farmacologia , Receptor alfa de Estrogênio/metabolismo , Genes Neoplásicos , Regiões Promotoras Genéticas , Tamoxifeno/farmacologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Genes Neoplásicos/efeitos dos fármacos , Humanos , Fosforilação , Ligação ProteicaRESUMO
The sensitivity of the polymerase chain reaction (PCR) in 35 consecutive outpatients with cutaneous leishmaniasis caused by Leishmania (Viannia) guyanensis was evaluated using, as gold standard, the in vitro isolation of the parasite through culture of aspirates of the cutaneous ulcers. All isolates were identified using electrophoretic enzyme analysis. Patients were mainly young males with recent onset disease without prior specific treatment. PCR was performed using DNA extracted from fresh frozen biopsies of cutaneous ulcers. The reaction used a pair of oligonucleotides that amplify the conserved region of the minicircle molecule. PCR showed 100% sensitivity (95% CI from 90.0 to 100.0). These results were similar to the visualization of amastigotes in imprint preparations of cutaneous biopsy tissue and the inoculation of biopsy material in golden hamsters. Despite the high sensitivity of the PCR, in this particular clinical setting of cutaneous leishmaniasis caused by L. (V.) guyanensis in the Brazilian Amazon, it appears that the method of choice for diagnosis should be the direct visualization of amastigotes using imprint preparations and the PCR reserved for those patients with negative imprint results.
