| 摘要: | Prostate cancer is a slow growing cancer which affects elderly males worldwide; although 10 percent of the younger population is reported at risk. There have been many hypotheses regarding its origin, but to date no actual cause has been adduced. However, there are many associated risk factors some of which include environmental factors, social and dietary habits. Cooking food at very high temperature generates acrylamide and glycidamide, chemicals previously reported to be mutagenic. Previous studies have reported association of acrylamide with colorectal, brain, lung and ovarian cancers. It was associated with treatment failures in advanced diseases due to drug resistance. Most conventional chemotherapeutic and hormonal agents have not been able to reduce the high rate of morbidity and mortality associated with the metastatic disease. Since most of these patients have lowered immunity; recent studies show that stimulation of their immune system could improve their ultimate response to treatment. Although drugs to target the immune checkpoint have been developed for treatment of prostate cancer, there is no appreciable improvement in the overall patient survival, probably due to poor penetration of the drug to the appropriate sites. Its current detection methods are nonspecific. With a view to developing a novel detection method for its early detection, we have identified androgen receptor as a molecular target as it is overexpressed in about 80 percent of castrate-resistant prostate cancer. We therefore worked with the aim to synthesize AuNRs@SPIOs-PEG-AR-ab nanoprobes to early detect prostate cancer formation, mutagenesis, and trace the route of metastasis employed by prostate cancer cells in vivo using the nanoprobes. To overcome treatment failures, we have conjugated CTLA-4-CA21 aptamer to the gold-coated iron oxide nanoprobes which can detect and kill prostate cancer cells even after metastasis has occurred.
Method: We synthesized gold-nanorods and iron oxide nanoparticles, functionalized them with organosilanes due to their large surface area to volume ratio, specific optical, electronic, magnetic and chemical properties including high surface energy, conjugated/coupled with the androgen receptor antibody, the CTLA-4-CA21 aptamer and the FITC/CyTE777 dyes. The nanoprobes were characterized, then used to assess cellular uptake efficiency, cytotoxicity and their ability to detect prostate cancer cells in vitro were assessed using nanoimaging techniques on a more malignant variant of the prostate cancer cell line induced in our laboratory with glycidamide and in nude mice.
Results: The nanoprobes have the wavelength maxima at 805 nm, the TEM images dimensions of gold nanorods and iron oxide nanocrystals were 200 ± 30 nm and 80 nm respectively. Glycidamide-treated cells showed evidence of more nanoprobes uptake, the nanoprobes has low level of toxicity. They have the potential to enter the cancer cells and target androgen receptors in the nuclei as shown by the deconvolution/confocal microscopy, near infrared fluorescence imaging and IVIS imaging results. These glycidamide transformed-cells showed reduced doubling time, epithelial mesenchymal transition with invadopodia. They were more proliferative, formed spheroids with invadopodia in matrigel invasive assays, and induced changes in androgen receptor, prostate specific antigen, and annexin A2 protein expressions which have been associated with aggressiveness in prostate cancer. The CTLA4-CA21 nanoprobes have the wavelength maxima at 803 nm, the TEM images dimensions which would enhance movement in the circulation. They show evidence of cell death, and the inhibitory effects on cell proliferation were dose-dependent on LNCaP, DU145, PC3 and BPH cells, with the greatest inhibition at 14.77 picomolar concentration. The near infrared imaging on the live cells showed marked cellular disruptions and apoptotic changes in the cancer cells.
Conclusion: With the wavelength maxima of 805 nm and 803 nm for AR nanoprobes and aptamer nanoprobes respectively which are within the “NIR imaging window”, our gold-shell iron oxide-core nanoprobes can penetrate deep tissues and overcome autofluorescence from tissues observed in the visible light region. The aggressiveness such as short doubling time, epithelial mesenchymal transition, formation of invadopodia, and upregulated levels of invasive biomarkers, exhibited by the glycidamide-treated prostate cancer cells compared to the parental cell lines could be due to the upregulation of androgen receptor promoted by glycidamide. With these great potentials the AuNRs@SPIOs-PEG-AR-ab nanoprobes can be used non-invasively in the early detection of prostate cancer. The inhibitory effects of the aptamer on cell proliferation were dose-dependent at picomolar concentration as well as the marked cellular disruptions and apoptotic changes in the live cancer cells in the near infrared imaging have proved the potency of the modified DNA CTLA-4 aptamer. Therefore they have great potential for use in the treatment of advanced prostate cancers and those associated with drug resistance. |
