A stable, inducible, dose-responsive ODC overexpression system in human cell lines

Effects of ODC on polyamine metabolism, hormone levels, cell proliferation and apoptosis in goose ovarian granulosa cells

Ornithine decarboxylase (ODC) plays an indispensable role in the process of polyamine biosynthesis. Polyamines are a pivotal part of living cells and have diverse roles in the regulation of cell proliferation and apoptosis, aging and reproduction. However, to date, there have been no reports about ODC regulating follicular development in goose ovaries. Here, we constructed ODC siRNA and overexpression plasmids and transfected them into goose primary granulosa cells (GCs) to elucidate the effects of ODC interference and overexpression on the polyamine metabolism, hormone levels, cell apoptosis and proliferation of granulosa cells. After interfering with ODC in GCs, the mRNA and protein levels of ODC and the content of putrescine were greatly decreased (P < 0.05). When ODC was overexpressed, ODC mRNA and protein levels and putrescine content were greatly increased (P < 0.05). The polyamine-metabolizing enzyme genes ornithine decarboxylase antizyme 1 (OAZ1) and spermidine / spermine-N1-acetyltransferase (SSAT) were significantly increased, and spermidine synthase (SPDS) was significantly decreased when ODC was downregulated (P < 0.05). OAZ1, SPDS and SSAT were significantly increased when ODC was upregulated (P < 0.05). In addition, after interference with ODC, progesterone (P4) levels in the culture medium of GCs increased greatly (P < 0.05), while the overexpression of ODC caused the P4 level to decrease significantly (P < 0.05). After ODC downregulation, granulosa cell activity was significantly reduced, the apoptosis rate was significantly increased, and the BCL-2 / BAX ratio was downregulated (P < 0.05). Under ODC overexpression, the activity of GCs was notably increased, the apoptosis rate was significantly reduced, and the BCL-2 / BAX protein ratio was upregulated (P < 0.05). Our study successfully induced ODC interference and overexpression in goose ovarian GCs, and ODC regulated mainly putrescine content in GCs with a slight influence on spermidine and spermine. Moreover, ODC participated in the adjustment of P4 levels in the culture medium of GCs, promoted granulosa cell proliferation and inhibited granulosa cell apoptosis.

Association between the ornithine decarboxylase G316A polymorphism and breast cancer survival

Ornithine decarboxylase (ODC) is a significant rate-limiting enzyme in polyamine synthesis, required for normal cell growth, and is highly expressed in various malignancies, including colorectal and breast cancer. In the present study, the associations between the ODC G316A single nucleotide polymorphism (SNP) and breast cancer-specific survival were investigated. In addition, the functional effects of this SNP were examined in the MCF-7 human breast cancer cell line. The present study recruited 300 stage I-III breast cancer cases, which were diagnosed at the Affiliated Cancer Hospital of Zhengzhou University (Zhengzhou, China) between 2002 and 2003, with follow-up visits conducted until May 2013. ODC G316A was genotyped (ODC GG vs. ODC AG/AA) in the 300 cases and the association of the genotypes with cancer-specific survival was analyzed. In the MCF-7 cell line, the ODC allele-specific binding of E-box transcription factors was determined using western blot and chromatin immunoprecipitation assays. Survival differences were observed between the two genotypes: Compared with the ODC GG genotype, patients with ODC GA/AA exhibited significantly higher survival rates (P<0.05). In cultured cells, the ODC SNP, which is flanked by two E-boxes, appeared to predict ODC promoter activity. Furthermore, the E-box activator c-MYC and repressor MAX interactor 1 were found to preferentially bind to ODC minor A-alleles compared with major G-alleles, in cultured MCF-7 cells. In conclusion, the results of the current study suggest that the regulation of ODC may affect survival in breast cancer patients and indicate a model in which the ODC SNP may be protective for breast adenoma recurrence and detrimental for survival following a diagnosis of breast cancer.