Rationale and clinical implication of combined chemotherapy with cisplatin and oestrogen in prostate cancer: primary evidence based on methylation analysis of oestrogen receptor-α
ABSTRACT To determine whether oestrogen enhances platinum sensitivity, and if promoter CpG methylation of the oestrogen receptor-alpha (ER-alpha) gene determines the potential of cisplatin-induced apoptosis in prostate cancer, as the high-mobility group 1 (HMG1) preferentially binds to cisplatin-modified DNA and is up-regulated after oestrogen treatment in breast cancer cell line MCF-7.
The study comprised prostate cancer cell lines (LNCaP and PC-3), 156 pathologically confirmed 156 radical prostatectomy samples and eight hormone-refractory prostate cancer (HRPC) samples (from needle biopsy). Expression of HMG1 in cell lines was analysed by Western blotting or differential reverse-transcription-polymerase chain reaction (PCR). The methylation status of ER-alpha was analysed by methylation-specific PCR using bisulphite DNA as a template or bisulphite DNA sequencing.
In LNCaP cells, treatment with oestrogen increased HMG1 expression and co-treatment with cisplatin and oestrogen reduced cell viability by accelerating apoptosis, compared with cisplatin alone. However, in PC-3, oestrogen did not up-regulate HMG1 or accelerate the cisplatin-induced apoptosis. Although ER-beta was expressed in both LNCaP and PC-3, ER-alpha was expressed only in LNCaP. Bisulphite DNA sequencing of the ER-alpha promoter showed partial methylation in LNCaP but complete methylation in PC-3. ER-alpha AS transfection diminished the cisplatin-induced apoptosis in oestrogen-treated LNCaP cells. In clinical samples there was ER-alpha hypermethylation in 40% of prostate cancers this correlated with Gleason score (GS, 31% for GS < 7, 50% for GS = 7 and 56% for GS > 7). In addition, five of eight HRPC samples showed ER-alpha hypermethylation.
These findings suggest that HMG1 induction as an enhancer of platinum sensitivity is mediated through interaction between oestrogen and ER-alpha. As CpG hypermethylation of the ER-alpha promoter is a frequent event in aggressive prostate cancer, negative conversion of ER-alpha methylation is essential to achieve the most beneficial effect when combined chemotherapy of cisplatin with oestrogen is used in patients with prostate cancer.
- SourceAvailable from: Hongquan Zhang[Show abstract] [Hide abstract]
ABSTRACT: Resistance to anticancer drugs is often observed in prostate cancer therapy. Kindlin-2 was recently found overexpressed during cancer progression. In this study, we examined the functional role of Kindlin-2 in cisplatin-induced prostate cancer cell death. Kindlin-2 was highly expressed in the androgen-insensitive (PC-3 and DU-145), but not in the androgen-sensitive cell lines (e.g., LNCaP). Overexpression of Kindlin-2 in LNCaP protected the cells from cisplatin-induced death, while Kindlin-2 knock-down in PC-3 cells enhanced cisplatin sensitivity. Mechanistically, Kindlin-2 regulation of the anti-apoptotic Bcl-xL may explain the increased cell death in the absence of Kindlin-2. Taken together, Kindlin-2 appears to play a functional role in prostate cancer cell sensitivity to cisplatin. Targeting Kindlin-2 may therefore improve drug efficacy and reduce drug doses, and would likely be beneficial for the treatment of prostate cancer.Cancer letters 12/2010; 299(1):54-62. DOI:10.1016/j.canlet.2010.08.003 · 5.02 Impact Factor
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ABSTRACT: A novel gene, rat pHyde, has been cloned by us recently. The rat pHyde was shown by the same group to have growth inhibitory effects on human prostate cancer through the induction of apoptosis. In this report, a human homologue, hpHyde of the rat pHyde, was cloned by cDNA libraries screening. The database search and in situ hybridization were used to map the genomic loci of hpHyde in human chromosome. The anti-prostate cancer effects of pHyde in conjunction with chemotherapy agent were analyzed by in vitro and in vivo assays using adenoviral vector expressing pHyde (AdRSVpHyde) in combination with DNA damaging chemotherapeutic agent, cisplatin, and docetaxel, respectively. Database search and FISH analysis consistently indicated that hpHyde gene localizes at human chromosome 2q14. Protein sequence analysis suggests that hpHyde may be a plasma membrane protein. hpHyde is differentially expressed in various normal human tissues and organs, suggesting that hpHyde may play roles in development and differentiation. Growth suppression and induction of apoptosis were additively greater in DU145 human prostate cancer cells treated with AdRSVpHyde and cisplatin than either agent alone both in vitro and in vivo. Moreover, AdRSVpHyde and docetaxel also have a similar additively inhibitory effect on DU145 cell growth. A novel gene hpHyde, the human homologue of rat pHyde, has been cloned and its genomic location in the human chromosome has been identified. Our results support the potential use of pHyde for prostate cancer gene therapy coupled with chemotherapy to improve therapeutic index.The Prostate 02/2009; 69(3):234-48. DOI:10.1002/pros.20867 · 3.57 Impact Factor
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ABSTRACT: Neuroendocrine (NE) cells were thought to be post-mitotic and non-proliferative. But it was recently reported that NE cells express, and induce surrounding cells to express potent antiapoptotic proteins. We hypothesize that neuroendocrine differentiation (NED), a common phenomenon in prostate cancer, is related to chemoresistance in prostate cancer. Androgen-independent human prostate cancer DU145 and PC-3 cells were exposed to epidermal growth factor (EGF). MTT assays evaluated changes in chemoresistance after EGF treatment, and flow cytometry examined EGF-induced cell cycle changes in DU145 cells. Western blotting, real-time RT-PCR and transmission electron microscopy were utilized to confirm NED. After stimulation with EGF, DU145 and PC-3 cells exhibited stronger resistance to cisplatin. Flow cytometry showed that EGF stimulation substantially decreased the proportion of DU145 cells in G(1) phase. EGF treatment increased the expression of neuron-specific enolase, a marker of NED induction. NED in prostate cancer is involved in the chemoresistance induced by EGF. EGF and/or the EGF receptor may be potential targets for medical intervention in chemo-resistant prostate cancer.Life sciences 05/2009; 84(25-26):882-7. DOI:10.1016/j.lfs.2009.03.021 · 2.30 Impact Factor