Human Prostate Cancer Cell Apoptosis Induced by Interferon-γ and Double-Stranded RNA and Studies on the Biological Roles of Transmembrane and Coiled-Coil Domains 1

Project I: Currently, chemotherapy is the only treatment for metastatic prostate cancer. However, due to toxicity and resistance, the currently available chemotherapeutic drugs are not good enough to control this disease. To find a novel and effective method to treat this disease, we studied the effect of interferons (IFNs) and double-stranded RNA (dsRNA) on the apoptosis of prostate cancer cells. Interestingly, pretreatment of PC3 cells, a human prostate adenocarcinoma cell line, with IFNs significantly sensitized these cells to dsRNA induced apoptosis, and cell apoptosis was confirmed by a variety of assays such as Annexin V, TUNEL, DNA fragmentation and the activity of caspase 3. In comparison with IFN-α or beta treatment, IFN-γ treatment remarkably augmented dsRNA-induced apoptosis in PC3 cells. By using mutant cell lines, we demonstrated that IFN-signaling is necessary for these effects. Silence of dsRNA-dependent protein kinase R (PKR) and RNAse L by siRNA did not have any significant impact on this event, suggesting that neither RNase L nor PKR is involved. Further investigation of the apoptotic pathway revealed that Bak, a pro-apoptotic member of the Bcl-2 family, is up-regulated by IFN-γ and dsRNA. Our findings may lead to the design of novel therapeutic strategies for prostate cancer.Project II: Transmembrane and coiled-coil domains 1 (TMCO1) is a membrane-associated protein with unknown function. Recently, a homozygous frame shift mutation, c.139_140delAG, has been identified in the TMCO1 gene in patients with TMCO1 defect syndrome (TDS). TDS is characterized by distinctive craniofacial dysmorphism, skeletal anomalies, and mental retardation. In order to study the biological function of this gene, human TMCO1 was expressed in both bacteria and mammalian cells. The recombinant TMCO1 expressed in bacteria was purified in order to prepare an antibody, and subcellular localization revealed that TMCO1 may be expressed in the mitochondria of cells. Further study showed that the lymphocytes isolated from peripheral blood of patients with TDS grew significantly faster than those from healthy individuals, suggesting that TMCO1 may be involved in the regulation of cell proliferation. In addition, we have generated a TMCO1 knock down cell line, which will be used to further study the molecular basis of TDS.