Aberrant Expressions of AP-2α Splice Variants in Pancreatic Cancer

Abstract

Objectives The present study was conducted to evaluate the expression and function of AP-2α isoforms in pancreatic ductal adenocarcinoma. Methods AP-2α expression was evaluated at RNA level by reverse transcription-polymerase chain reaction and at the protein level by western blotting and immunofluorescence. Its function as a transcription factor was evaluated in transient transfection experiments: DNA binding properties by electromobility shift assay and transactivation capabilities by Luciferase assay. Results Multiple alternative splicing events of AP-2α messenger occurred in all human pancreatic cancer cell lines, including a novel isoform, termed variant 6, which was not present in HeLa cells. At the protein level, except for one cell line, all pancreatic cancer cell lines expressed high nuclear levels of AP-2α. We also showed that AP-2α expressed by the pancreatic cancer cell lines could bind its cognate recognition site and activate transcription. However, variant 6 while not able to activate transcription did not act in a dominant negative manner when co-transfected with the full length protein. Conclusions Multiple isoforms of AP-2α are highly expressed in pancreatic cancer cell lines including a new isoform, AP-2α variant 6, which appears to be pancreatic cancer specific and is deprived of transcriptional activity.

Integrated single-cell and bulk gene expression and ATAC-seq reveals heterogeneity and early changes in pathways associated with resistance to cetuximab in HNSCC-sensitive cell lines

“…48 TFAP2A upregulation is a feature of other tumour types, such as neuroblastoma, pancreatic cancer and acute myeloid leukaemia. 49,50,51 In our in vitro models, TFAP2A knockdown resulted in slower cell growth showing the relevance of this transcription factor to HNSCC proliferation in vitro. This finding together with the observation that cetuximab has a synergistic effect is evidence that TFAP2A downstream targets could be new therapeutic markers for combination approaches that will result in prolonged disease control.…”

Comprehensive Dissection of Transcriptome Data and Regulatory Factors in Pancreatic Cancer Cells

“…In this study, Sancho et al (2015) also showed that over-expression of MYC diminished stem celllike properties of the tumor samples in comparison with their normal counterparts. A possible mechanism by which MYC is down-regulated may be by TFAP2A, which was found to negatively regulate MYC [Gaubatz et al, 1995;Carri ere et al, 2011], and also a protein for which our analysis revealed to be up-regulated in pancreatic tumor samples (Fig. This was due to the fact that MYC plays significant roles in the up-regulation of metabolic processes, and the down-regulation of MYC allowed cells to survive under conditions of limited energy sources.…”

“…The down-regulation of MYC in different independent studies and the emergence of reports about its function in pancreatic ductal adenocarcinoma show a paradoxically complex regulatory mechanism for MYC which needs to be further clarified. A possible mechanism by which MYC is down-regulated may be by TFAP2A, which was found to negatively regulate MYC [Gaubatz et al, 1995;Carri ere et al, 2011], and also a protein for which our analysis revealed to be up-regulated in pancreatic tumor samples ( Fig. 1b).…”

Integrated single cell and bulk multi-omics reveals heterogeneity and early changes in pathways associated with cetuximab resistance in HNSCC sensitive cell lines

“…It is critical to determine the timing in treatment that reversible epigenetic alterations develop to allow alternative therapies to be effective. Short term exposure to targeted therapies can induce reversible chromatin changes that will lead to resistance, while chronic exposure induces DNA methylation changes that are more steady and observed in stable resistant states (34).…”

“…In nasopharyngeal carcinoma, TFAP2A silencing in vitro and in vivo results in slower cancer cell proliferation and that patients with high tumor levels of the gene present poorer survival compared to those with lower expression (36). TFAP2A up-regulation is a feature of other tumor types such as neuroblastoma, pancreatic cancer and acute myeloid leukemia [32][33][34] . In our in vitro models, TFAP2A knock-down resulted in slower cell growth showing the relevance of this transcription factor to HNSCC proliferation in vitro.…”