Programmed cell death 4 gene (PDCD4), an in vivo repressor of transformation, was originally isolated from a human glioma library by screening it with an antibody against a nuclear antigen in proliferating cells. PDCD4 functions as a transformation repressor by inhibiting the activity of the RNA helicase, eIF4A. We previously showed that retinoids, anti-estrogens and HER2/neu antagonist induce PDCD4 expression in human breast cancer cell lines. Very little is known about the expression of PDCD4 in human breast cancer tissues or the significance of the PDCD4 expression in breast cancer. To gain insight into the pattern of the PDCD4 expression in breast tissues, we performed an immunohistochemical analysis of the PDCD4 expression in 80 archived, normal and ductal breast carcinoma tissues (invasive and carcinoma in situ) (DCIS) and correlated PDCD4 expression with expression of known prognostic markers in breast cancer (ER, PR and HER2/neu). To assess the role of methylation on PDCD4 expression in breast cancer cells, breast cancer cell lines were treated with the demethylating agent 5-deoxy-azacytidine and analyzed for PDCD4 expression. We observed primarily nuclear localization of PDCD4 in ductal carcinoma in situ compared to normal breast tissues where the PDCD4 expression was predominantly cytoplasmic. This was seen more frequently in DCIS cases that were ER positive and HER2/neu negative samples. PDCD4 expression was markedly decreased in the invasive ductal carcinoma. We did not observe any significant relationship between PDCD4 expression and the expression of RAR or PR. In T-47D, MDA-MB-435 and MDA-MB-231 cells, treatment with 5-deoxy-azacytidine did not result in an increased expression of PDCD4. The present study demonstrated altered cellular localization of PDCD4 when comparing normal breast to neoplastic breast tissues. In addition, there was a decreased expression of PDCD4 in breast cancer when compared with normal breast tissue. A loss of the PDCD4 expression in breast cancer cell lines does not appear to result from hypermethylation of the PDCD4 promoter.
"In addition, PDCD4 was reported to be an inhibitor of neoplastic transformation and metastasis (48, 49). In breast cancer tissue, PDCD4 is seen in both normal and malignant epithelial cells and localizes to the nuclei and/or the cytoplasm (50). It remains to be established if miR-21 is involved in the regulation of all of these pivotal functions of PDCD4. "
[Show abstract][Hide abstract] ABSTRACT: Trastuzumab is established as standard care for patients with HER2-positive breast cancer both in the adjuvant and metastatic setting. However, 50% of the patients do not respond to the trastuzumab therapy, and therefore new predictive biomarkers are highly warranted. MicroRNAs (miRs) constitute a new group of biomarkers and their cellular expression can be determined in tumor samples by in situ hybridization (ISH) analysis. miR-21 is highly prevalent and up-regulated in breast cancer and has been linked to drug resistance in clinical and in vitro settings. To determine expression patterns of miR-21 in high-grade breast cancers, we examined miR-21 expression in 22 HER2-positive tumors and 15 HER2-negative high-grade tumors by ISH. The histological examination indicated that patient samples could be divided into three major expression patterns: miR-21 predominantly in tumor stroma, predominantly in cancer cells, or in both stromal and cancer cells. There was no obvious difference between the HER2-positive and HER2-negative tumors in terms of the miR-21 expression patterns and intensities. To explore the possibility that miR-21 expression levels and/or cellular localization could predict resistance to adjuvant trastuzumab in HER2-positive breast cancer patients, we analyzed additional 16 HER2-positive tumors from patients who were treated with trastuzumab in the adjuvant setting. Eight of the 16 patients showed clinical recurrence and were considered resistant. Examination of the miR-21 expression patterns and intensities revealed no association between the miR-21 scores in the cancer cell population (p = 0.69) or the stromal cells population (p = 0.13) and recurrent disease after adjuvant trastuzumab. Thus, our findings show that elevated miR-21 expression does not predict resistance to adjuvant trastuzumab.
Frontiers in Oncology 08/2014; 4:207. DOI:10.3389/fonc.2014.00207
"anisms , such as DNA methylation , might also contribute to pdcd4 regulation . The knock - down of DNA methyltransferase 1 in a hepatocellular carcinoma cell line and , therefore , demethylation of DNA induced pdcd4 expression ( Fan et al . , 2007 ) , even if a demethylating agent resulted in no change in Pdcd4 levels in breast cancer cell lines ( Wen et al . , 2007 ) . In addition , pdcd4 5 - CpG island methylation was associated with reduced Pdcd4 mRNA levels in human glioma cell lines and tissue , and restoration of pdcd4 was observed after blocking methylation in glioma cells ( Gao et al . , 2008 ) . An overview of the known regulatory mechanisms for Pdcd4 levels is shown in Figure 2 . In concl"
[Show abstract][Hide abstract] ABSTRACT: Pdcd4 (programmed cell death 4) has been known as a tumour suppressor gene and potential target for anticancer therapies for several years. Initially, Pdcd4 was identified as a gene that is up-regulated during apoptosis, but its precise role still remains to be defined. However, there is increasing evidence that Pdcd4 levels influence transcription, as well as translation, modulate different signal transduction pathways and might act as a tumour suppressor. Interestingly, recent data suggest that Pdcd4 function may depend on cell type and/or genetic background. This review summarizes the current knowledge regarding the function and regulation of Pdcd4.
Biology of the Cell 07/2009; 101(6):309-17. DOI:10.1042/BC20080191 · 3.51 Impact Factor
"In breast cancer a decreased expression of PDCD4 was observed in comparison to normal breast tissue. Expression of PDCD4 was mainly localized in nuclei in DCIS while it was predominantly expressed in cytoplasm in normal breast tissue . In contrast, we found that the PDCD4 expression shifted from nuclei to cytoplasm with the progression of breast tissue from normal to IDC, whereas nuclear expression of PDCD4 decreased from normal breast to FEA, DCIS and IDC. "
[Show abstract][Hide abstract] ABSTRACT: Flat epithelial atypia (FEA) of the breast is characterised by a few layers of mildly atypical luminal epithelial cells. Genetic changes found in ductal carcinoma in situ (DCIS) and invasive ductal breast cancer (IDC) are also found in FEA, albeit at a lower concentration. So far, miRNA expression changes associated with invasive breast cancer, like miR-21, have not been studied in FEA.
We performed miRNA in-situ hybridization (ISH) on 15 cases with simultaneous presence of normal breast tissue, FEA and/or DCIS and 17 additional cases with IDC. Expression of the miR-21 targets PDCD4, TM1 and PTEN was investigated by immunohistochemistry.
Two out of fifteen cases showed positive staining for miR-21 in normal breast ductal epithelium, seven out of fifteen cases were positive in the FEA component and nine out of twelve cases were positive in the DCIS component. A positive staining of miR-21 was observed in 15 of 17 IDC cases. In 12 cases all three components were present in one tissue block and an increase of miR-21 from normal breast to FEA and to DCIS was observed in five cases. In three cases the FEA component was negative, whereas the DCIS component was positive for miR-21. In three other cases, normal, FEA and DCIS components were negative for miR-21 and in the last case all three components were positive. Overall we observed a gradual increase in percentage of miR-21 positive cases from normal, to FEA, DCIS and IDC. Immunohistochemical staining for PTEN revealed no obvious changes in staining intensities in normal, FEA, DCIS and IDC. Cytoplasmic staining of PDCD4 increased from normal to IDC, whereas, the nuclear staining decreased. TM1 staining decreased from positive in normal breast to negative in most DCIS and IDC cases. In FEA, the staining pattern for TM1 was similar to normal breast tissue.
Upregulation of miR-21 from normal ductal epithelial cells of the breast to FEA, DCIS and IDC parallels morphologically defined carcinogenesis. No clear relation was observed between the staining pattern of miR-21 and its previously reported target genes.
BMC Cancer 02/2009; 9(1):163. DOI:10.1186/1471-2407-9-163 · 3.36 Impact Factor
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