Expression Analysis and Regulation of Steapi in Prostate Cell Lines and in Tissue Microrrays of Prostate Tumors
The six transmembrane epithelial antigen of the prostate 1 (STEAP1) gene was firstly identified as over-expressed in prostate cancer, but since then, several studies have shown that STEAP1 is also over-expressed in several types of tumors. As STEAP1 expression is almost absent in normal tissues, it...
Saved in:
| Main Author: | |
|---|---|
| Format: | Dissertation |
| Language: | English |
| Published: |
ProQuest Dissertations & Theses
01-01-2012
|
| Subjects: | |
| Online Access: | Get full text |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | The six transmembrane epithelial antigen of the prostate 1 (STEAP1) gene was firstly identified as over-expressed in prostate cancer, but since then, several studies have shown that STEAP1 is also over-expressed in several types of tumors. As STEAP1 expression is almost absent in normal tissues, it has been pointed STEAP1 as a potential biomarker and immunotherapeutic target for cancer. However, the clinical significance of STEAP1 expression in prostate cells remains to be clarified.At the moment, very little is known about the regulation of STEAP1 in prostate cells, and the mechanisms underlying the over-expression of STEAP1 in prostate cancer remain unknown. In addition, another STEAP1-related gene is encoded by human genome, referred to STEAP1B gene. This gene originates two different transcripts, STEAP1B1 and STEAP1B2, probably resulting from alternative splicing. However, no studies are found in the literature reporting the characterization of STEAP1B expression in prostate cells.Therefore, the main aims of this study was to analyze the STEAP1, STEAP1B1 and STEAP1B2 mRNA and STEAP1 protein expression in neoplastic and non-neoplastic prostate cell lines by real-time PCR and Western blot, respectively; and to evaluate if epigenetic mechanism is involved in regulation of STEAP1 gene expression by bisulfite sequencing PCR. In order to evaluate the clinical significance of STEAP1 expression in prostate cancer, tissue microarrays were constructed and STEAP1 immunoreactivity was determined by immunohistochemical method. A score scale for STEAP1 immunoreactivity was established in order to establish associations between STEAP1 immunoreactivity and histologic diagnosis or the clinic-pathological data of patients.Our results show that STEAP1 is highly expressed in LNCaP and PC3 neoplastic cells when compared to PNT1A and PNT2 non-neoplastic cells. On the other hand, STEAP1B1 and STEAP1B2 showed a slight expression in prostate cell lines. Regarding the methylation rate of STEAP1 gene promoter region, no significant differences were found between neoplastic (LNCaP) and non-neoplastic (PNT1A and PNT2) prostate cells, suggesting that STEAP1 over-expression in LNCaP cells should not be explained by hypomethylation at promoter region of STEAP1 gene. However, due to amplification of STEAP1 and STEAP1B gene using some sets of primers, these results should be confirmed through another strategy.By immunohistochemistry technique, it was found that STEAP1 is expressed in cell membrane and cytoplasm of epithelial cells, and it is also visible a weaker staining in stromal cells. Our results show that STEAP1 is over-expressed in prostate cancer and PIN lesions when compared to adjacent normal tissue or benign prostate hyperplasia, suggesting that STEAP1 gene may become over-expressed even before cancer development. Finally, it was found that there is a relationship between the STEAP1 immunoreactivity and Gleason score, but not with other clinic-pathologic data such as age, total-PSA, free-PSA, TNM and bone metastasis.In summary, we conclude that STEAP1 is over-expressed in neoplastic cell lines when compared to non-neoplastic prostate cells, but its over-expression doesn’t seem to involve epigenetic mechanisms. STEAP1 is over-expressed in human prostate cancer cases and PIN lesions, and its immunoreactivity correlates positively with Gleason score. However, more studies are required to clarify the clinical significance of STEAP1 expression in prostate cancer. |
|---|---|
| ISBN: | 9798383433959 |