Abstract 4482: Osteopontin, p53 and PTEN isoforms expression patterns in endometrium carcinoma cell lines
Authors: Vanessa F. Franco, Nataly dos Santos Melo, Iaci N. Soares, Ya-Ting Hsu, Ya-Ting, Tim H. Huang, Wallace M. Araujo, José A. Morgado-Diaz, Jerson L. Silva, Etel Rodrigues Pereira Gimba
Journal: Cancer Research (2017)

Abstract Total osteopontin (OPN) is overexpressed in endometrium carcinoma (EC) and modifications at TP53 and PTEN genes correspond to major genetic alterations in these tumors. Althought total OPN expression has been correlated to p53 and PTEN expression, no data is available regarding OPN splice variants and their association to p53 and PTEN isoforms expression. OPN has three splicing isoforms (OPN-SI), named OPNa, OPNb and OPNc, while p53 has at least 12 variants, such as p53 (full lenght), p53β, p53γ, Δ40p53, Δ133p53 and Δ160p53. Moreover, PTEN splicing isoforms (PTEN-SI) are named vs-fl (full lenght variant), vs-3a-3c, vs-5a-5d, and vs-D6. We aimed to evaluate the expression profile of OPN, p53 and PTEN isoforms as a first approach to establish their presumptive associations and functional interactions in endometrial tumoral and non tumoral cells. Total RNA has been extracted from endometrial non-tumoral (E6/E7 and EM42) and tumoral (Ishikawa, RL95-2, AN3CA and KLE) cell lines, followed by cDNA synthesis. Transcriptional and protein expression patterns have been evaluated for OPN, p53 or PTEN isoforms, using quantitative real time PCR, immunoblot or immunofluorescence. OPNa is overexpressed in tumoral and non-tumoral cell lines in relation to OPNb and OPNc. Regarding p53, the full lengh isoform is overexpressed, followed by Δ40p53, in relation to other variants in EC cells. Conversely, Δ40p53 it is the major expressed transcript in both EM42 and E6/E7 non-tumoral cells. Otherwise, in EC and endometrial non-tumoral cells, PTEN vs-fl isoform is overexpressed in relation to the other splice variants. Specifically in E6/E7 cells, all PTEN-SI, except vs-3b e vs-D6, are overexpressed in relation to EC cell lines. At the protein level, both p53 and PTEN isoforms are overexpressed in E6/E7 cells, when compared to EC cells. Of note, distinct isoforms for most of these variant transcripts have not been detected at the protein level. Our data demonstrate that full lenght OPN, p53 and PTEN are the major expressed variants in EC tumor cell lines. However, most of these transcript variants display differential expression between endometrial tumor and non-tumoral cells and also among distinct EC cell lines. These data provide early evidence that these variants can differently modulate the expression and functional roles of their full length couterparts. Further work should investigate the impact of OPNa overerexpression on p53 and PTEN isoforms and their putative cellular and molecular roles on modulating p53 and PTEN tumor supressive roles. Citation Format: Vanessa F. Franco, Nataly dos Santos Melo, Iaci N. Soares, Ya-Ting Hsu, Ya-Ting, Tim H. Huang, Wallace M. Araujo, José A. Morgado-Diaz, Jerson L. Silva, Etel Rodrigues Pereira Gimba. Osteopontin, p53 and PTEN isoforms expression patterns in endometrium carcinoma cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4482. doi:10.1158/1538-7445.AM2017-4482