Search

The castration-resistant (CR) prostate cancer (PCa) is lethal and is the second leading cause of cancer-related deaths in U.S. males. To develop effective treatments toward CR PCa, we investigated reactive oxygen species (ROS) signaling pathway for its role involving in CR PCa progression. ROS can regulate both cell growth and apoptosis: a moderate increase of ROS promotes proliferation; its substantial rise results in cell death. p66Shc protein can increase oxidant species production and its elevated level is associated with the androgen-independent (AI) phenotype of CR PCa cells; while heme oxygenase-1 (HO-1) is an antioxidant enzyme and elevated in a sub-group of metastatic PCa cells. In this study, our data revealed that HO-1 and p66Shc protein levels are co-elevated in various AI PCa cell lines as well as p66Shc cDNA-transfected cells. Knockdown and/or inhibition of either p66Shc or HO-1 protein leads to reduced tumorigenicity as well as a reduction of counterpart protein. Knockdown of HO-1 alone results in increased ROS levels, nucleotide and protein oxidation and induction of cell death. Together, our data indicate that elevated HO-1 protein levels protect PCa cells from otherwise apoptotic conditions induced by aberrant p66Shc/ROS production, which thereby promotes PCa progression to the CR phenotype. p66Shc and HO-1 can serve as functional targets for treating CR PCa.

Prostate cancer is the most commonly diagnosed solid tumor and the second leading cause of cancer-related deaths in men in the United States. While localized prostate cancer has an excellent prognosis for patients, about one-third of patients are diagnosed with high-risk disease, including metastatic cancer. The 5-year survival rate of metastatic prostate cancer is only about 30%. Due to the androgen dependence of prostate cancer cells, androgen-deprivation therapy is the standard of care for metastatic prostate cancer, which includes both surgical and medical approaches. Nevertheless, androgen-deprivation therapy in general is not curative; patients can develop castration-resistant prostate cancer. Despite current chemotherapies, including the utilization of novel androgen signaling inhibitors and immunotherapy, patients still succumb to the disease. Hence, castration-resistant prostate cancer is a lethal disease. Combination treatment is a strategy for treating this lethal disease and thus will be the focus of discussion in this chapter.

Prostate cancer (PCa) is the most commonly diagnosed solid tumor and the second leading cause of cancer-related deaths in U.S. men in 2020. Androgen-deprivation therapy (ADT) is the standard of care for metastatic PCa. Unfortunately, PCa relapse often occurs one to two years after initiation of ADT, resulting in the development of castration-resistant PCa (CRPCa), a lethal disease. While several anticancer agents such as docetaxel, abiraterone acetate, and enzalutamide are currently utilized to extend a patient’s life after development of CRPCa, patients will eventually succumb to the disease. Hence, while targeting androgen signaling and utilization of docetaxel remain the most crucial agents for many of these combinations, many studies are attempting to exploit other vulnerabilities of PCa cells, such as inhibition of key survival proteins, anti-angiogenesis agents, and immunotherapies. This review will focus on discussing recent advances on targeting therapy. Several novel small molecules will also be discussed.

Dabrafenib, an FDA-approved oral anticancer drug, prevents cisplatin- and noise-induced hearing loss in animal models., Hearing loss caused by noise, aging, antibiotics, and chemotherapy affects 10% of the world population, yet there are no Food and Drug Administration (FDA)-approved drugs to prevent it. Here, we screened 162 small-molecule kinase-specific inhibitors for reduction of cisplatin toxicity in an inner ear cell line and identified dabrafenib (TAFINLAR), a BRAF kinase inhibitor FDA-approved for cancer treatment. Dabrafenib and six additional kinase inhibitors in the BRAF/MEK/ERK cellular pathway mitigated cisplatin-induced hair cell death in the cell line and mouse cochlear explants. In adult mice, oral delivery of dabrafenib repressed ERK phosphorylation in cochlear cells, and protected from cisplatin- and noise-induced hearing loss. Full protection was achieved in mice with co-treatment with oral AZD5438, a CDK2 kinase inhibitor. Our study explores a previously unidentified cellular pathway and molecular target BRAF kinase for otoprotection and may advance dabrafenib into clinics to benefit patients with cisplatin- and noise-induced ototoxicity.

Despite recent advances in modern medicine, castration-resistant prostate cancer remains an incurable disease. Subpopulations of prostate cancer cells develop castration-resistance by obtaining the complete steroidogenic ability to synthesize androgens from cholesterol. Statin derivatives, such as simvastatin, inhibit cholesterol biosynthesis and may reduce prostate cancer incidence as well as progression to advanced, metastatic phenotype. In this study, we demonstrate novel simvastatin-related molecules SVA, AM1, and AM2 suppress the tumorigenicity of prostate cancer cell lines including androgen receptor-positive LNCaP C-81 and VCaP as well as androgen receptor-negative PC-3 and DU145. This is achieved through inhibition of cell proliferation, colony formation, and migration as well as induction of S-phase cell-cycle arrest and apoptosis. While the compounds effectively block androgen receptor signaling, their mechanism of inhibition also includes suppression of the AKT pathway, in part, through disruption of the plasma membrane. SVA also possess an added effect on cell growth inhibition when combined with docetaxel. In summary, of the compounds studied, SVA is the most potent inhibitor of prostate cancer cell tumorigenicity, demonstrating its potential as a promising therapeutic agent for castration-resistant prostate cancer.

The treatment of castration-resistant (CR) prostate cancer (PCa) is limited. A sub-population of CR PCa tumors can synthesize androgens for intracrine androgen receptor (AR) activation, thus targeting androgen biosynthesis could be an effective therapeutic option for these patients. We determined that androgen biosynthesis inhibitors simvastatin, atorvastatin, and ketoconazole directly inhibit growth, migration, and colony formation of LNCaP C-81 cells, which exhibit de novo androgen biosynthesis, with simvastatin being the most effective. Importantly, in combination treatments, statins specifically enhanced growth suppression with added effects by anti-androgen abiraterone acetate on the CR PCa cells. Thus, statins can be used in conjunction with abiraterone acetate to enhance anti-androgen therapy for CR PCa.

Prostate cancer (PCa) remains the second leading cause of cancer-related deaths in U.S. men due to the development of the castration-resistant (CR) PCa phenotype. A useful cell model for analysis of the molecular mechanism of PCa progression is required for developing targeted therapies toward CR PCa. In this study, we established a PCa cell progressive model in three separate cell lines, of which androgen-independent (AI) cells were derived from respective androgen-sensitive (AS) cells. Those AI PCa cells obtain the biochemical properties of the clinical CR phenotype, including AR and PSA expression as well as enhanced proliferation and tumorigenicity under androgen-deprived conditions. Thus, those AI cells recapitulate CR PCa and exhibit increased oxidant species levels as well as enhanced signaling of proliferation and survival pathways. H(2)O(2) treatment directly enhanced AS cell growth and migration, which was counteracted by antioxidant N-acetyl cysteine (NAC). We further identified p66Shc protein enhances the production of oxidant species which contributes to phenotypic and cell signaling alterations from AS to AI PCa cells. H(2)O(2)-treated LNCaP-AS cells had a similar signaling profile to that of LNCaP-AI or p66Shc subclone cells. Conversely, the oxidant species-driven alterations of LNCaP-AI and p66Shc subclone cell signaling is mitigated by p66Shc knockdown. Moreover, LNCaP-AI cells and p66Shc subclones, but not LNCaP-AS cells, develop xenograft tumors with metastatic nodules, correlating with p66Shc protein levels. Together, the data shows that p66Shc enhances oxidant species production that plays a role in promoting PCa progression to the CR stage.

Currently, prostate cancer (PCa) remains the most commonly diagnosed solid tumor and the second leading cause of cancer-related deaths in US men. Most of these deaths are attributed to the development of castration-resistant (CR) PCa. ErbB-2 and ErbB family members have been demonstrated to contribute to the progression of this lethal disease. In this review, we focus on updating the role of ErbB-2 in advanced PCa progression and its regulation, including its regulation via ligand activation, miRNAs and protein phosphorylation. We also discuss its downstream signaling pathways, including AKT, ERK1/2 and STATs, involved in advanced PCa progression. Additionally, we evaluate the potential of ErbB-2, focusing on its protein hyper-phosphorylation status, as a biomarker for aggressive PCa as well as the effectiveness of ErbB-2 as a target for the treatment of CR PCa via a multitude of approaches, including orally available inhibitors, intratumoral expression of cPAcP, vaccination and immunotherapy.

Metastatic castration-resistant (CR) prostate cancer (PCa) is a lethal disease for which no effective treatment is currently available. p66Shc is an oxidase previously shown to promote androgen-independent cell growth through generation of reactive oxygen species (ROS) and is elevated in clinical PCa and multiple CR PCa cell lines. We hypothesize p66Shc also increases the migratory activity of PCa cells through ROS and investigate the associated mechanism. Using the transwell assay, our study reveals that the level of p66Shc protein correlates with cell migratory ability across several PCa cell lines. Furthermore, we show hydrogen peroxide treatment induces migration of PCa cells that express low levels of p66Shc in a dose-dependent manner, while antioxidants inhibit migration. Conversely, PCa cells that express high levels of endogenous p66Shc or by cDNA transfection possess increased cell migration which is mitigated upon p66Shc shRNA transfection or expression of oxidase-deficient dominant-negative p66Shc W134F mutant. Protein microarray and immunoblot analyses reveal multiple proteins, including ErbB-2, AKT, mTOR, ERK, FOXM1, PYK2 and Rac1, are activated in p66Shc-elevated cells. Their involvement in PCa migration was examined using respective small-molecule inhibitors. The role of Rac1 was further validated using cDNA transfection and, significantly, p66Shc is found to promote lamellipodia formation through Rac1 activation. In summary, the results of our current studies clearly indicate p66Shc also regulates PCa cell migration through ROS-mediated activation of migration-associated proteins, notably Rac1.

Metastatic prostate cancer (mPCa) relapses after a short period of androgen deprivation therapy and becomes the castration-resistant prostate cancer (CR PCa); to which the treatment is limited. Hence, it is imperative to identify novel therapeutic agents towards this patient population. In the present study, antiproliferative activities of novel imidazopyridines were compared. Among three derivatives, PHE, AMD and AMN, examined, AMD showed the highest inhibitory activity on LNCaP C-81 cell proliferation, following dose- and time-dependent manner. Additionally, AMD exhibited significant antiproliferative effect against a panel of PCa cells, but not normal prostate epithelial cells. Further, when compared to AMD, its derivative DME showed higher inhibitory activities on PCa cell proliferation, clonogenic potential and in vitro tumorigenicity. The inhibitory activity was apparently in part due to the induction of apoptosis. Mechanistic studies indicate that AMD and DME treatments inhibited both AR and PI3K/Akt signaling. The results suggest that better understanding of inhibitory mechanisms of AMD and DME could help design novel therapeutic agents for improving the treatment of CR PCa.

Purpose and Background: Prostate cancer (PCa) is the second leading cause of cancer-related death in United States men. Androgen deprivation therapy is the standard-of-care treatment for metastatic PCa; most patients eventually relapse and develop castration-resistant (CR) tumors that currently have no effective treatment. Thus, a useful cell model for analysis of the molecular mechanism of PCa progression is required for developing targeted therapies for CR PCa. In this study, we established a PCa cell progressive model in three independent cell lines, of which androgen-independent (AI) cells were derived from respective androgen-sensitive (AS) cells, recapitulating clinical PCa progression. Experimental Methods: AS and AI human prostate adenocarcinoma cell lines LNCaP, MDA PCa2b and VCaP were utilized in this study to demonstrate the molecular and signaling alterations seen in CR PCa. Stable p66Shc cDNA transfected subclones were established from LNCaP-AS cells. The tumorigenicity of AS and AI cells as well as AS PCa cells treated with H2O2 and NAC were evaluated via trypan blue exclusion, transwell migration, clonogenic assays and xenograft mouse models. The signaling profiles including phosphoprotein microarray and immunoblotting were conducted. Results: AI PCa cells have enhanced tumorigenicity, recapitulating the clinical CR phenotype, including AR expression, proliferation and tumorigenicity under androgen-deprived conditions. Further, AI cells exhibit increased ROS levels as well as enhanced signaling of proliferation and survival pathways. We further identified oxidase p66Shc as one of the potential sources of the ROS-mediated phenotypic and cell signaling alterations in AI PCa cells. LNCaP-AI cells and p66Shc subclones have a greater oxidative environment compared to LNCaP-AS cells. Increased ROS via H2O2 enhanced AS cell growth and migration, which was counteracted by antioxidant NAC. Treatment of LNCaP-AS cells with H2O2 resulted in a similar signaling profile to that of LNCaP-AI or p66Shc subclone cells. Further, the ROS-driven alterations of p66Shc subclone cell signaling can be mitigated via p66Shc knockdown or inactive p66Shc mutant. Moreover, LNCaP-AI cells and p66Shc subclones, but not LNCaP-AS cells, develop xenograft tumors with metastatic nodules. Molecular profiling showed that alterations of signaling in LNCaP-AI cells and p66Shc subclones attributed to p66Shc/ROS. Conclusions: We report the establishment of a PCa cell progression model in three commonly used PCa cell lines that replicates clinical PCa progression from the AS to the AI/CR phenotype. Altogether, the data shows ROS produced by p66Shc promotes PCa tumorigenicity and progression to the CR phenotype. Further characterization of the PCa progressive model will aid in the understanding of advanced PCa progression to help in treatment of this lethal disease. Citation Format: Dannah Miller, Matthew Ingersoll, Arpita Chatterjee, Rebecca Oberley-Deegan, Ming-Fong Lin. p66Shc/ROS enhances the progression of androgen-sensitive towards castration-resistant prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4285.

Prostate cancer (PCa) is the second leading cause of cancer-related death afflicting United States males. Most treatments to-date for metastatic PCa include androgen-deprivation therapy and second-generation anti-androgens such as abiraterone acetate and enzalutamide. However, a majority of patients eventually develop resistance to these therapies and relapse into the lethal, castration-resistant form of PCa to which no adequate treatment option remains. Hence, there is an immediate need to develop effective therapeutic agents toward this patient population. Imidazopyridines have recently been shown to possess Akt kinase inhibitory activity; thus in this study, we investigated the inhibitory effect of novel imidazopyridine derivatives HIMP, M-MeI, OMP, and EtOP on different human castration-resistant PCa cells. Among these compounds, HIMP and M-MeI were found to possess selective dose- and time-dependent growth inhibition: they reduced castration-resistant PCa cell proliferation and spared benign prostate epithelial cells. Using LNCaP C-81 cells as the model system, these compounds also reduced colony formation as well as cell adhesion and migration, and M-MeI was the most potent in all studies. Further investigation revealed that while HIMP primarily inhibits PCa cell growth via suppression of PI3K/Akt signaling pathway, M-MeI can inhibit both PI3K/Akt and androgen receptor pathways and arrest cell growth in the G2 phase. Thus, our results indicate the novel compound M-MeI to be a promising candidate for castration-resistant PCa therapy, and future studies investigating the mechanism of imidazopyridine inhibition may aid to the development of effective anti-PCa agents.

The inactivation of tumor suppressor genes (TSGs) plays a vital role in the progression of human cancers. Nevertheless, those ubiquitous TSGs have been shown with limited roles in various stages of diverse carcinogenesis. Investigation on identifying unique TSG, especially for early stage of carcinogenesis, is imperative. As such, the search for organ-specific TSGs has emerged as a major strategy in cancer research. Prostate cancer (PCa) has the highest incidence in solid tumors in US males. Cellular prostatic acid phosphatase (cPAcP) is a prostate-specific differentiation antigen. Despite intensive studies over the past several decades on PAcP as a PCa biomarker, the role of cPAcP as a PCa-specific tumor suppressor has only recently been emerged and validated. The mechanism underlying the pivotal role of cPAcP as a prostate-specific TSG is, in part, due to its function as a protein tyrosine phosphatase (PTP) as well as a phosphoinositide phosphatase (PIP), an apparent functional homologue to phosphatase and tensin homolog (PTEN) in PCa cells. This review is focused on discussing the function of this authentic prostate-specific tumor suppressor and the mechanism behind the loss of cPAcP expression leading to prostate carcinogenesis. We review other phosphatases' roles as TSGs which regulate oncogenic PI3K signaling in PCa and discuss the functional similarity between cPAcP and PTEN in prostate carcinogenesis.

Purpose and Background: Prostate cancer (PCa) remains the most commonly diagnosed solid tumor and is the second leading cause of cancer-related death in United States men. While androgen deprivation therapy is the current standard-of-care treatment for metastatic PCa, most patients eventually relapse and develop castration-resistant (CR) tumors for which there is currently no effective treatment. p66Shc, a 66 kDa Src and collagen homologue oxidase, is elevated in clinical PCa as well as multiple PCa cell lines which correspond with advanced CR PCa. Additionally, p66Shc has been demonstrated to promote proliferation in PCa cell lines via generation of reactive oxygen species (ROS). This study is the first to demonstrate p66Shc also regulates PCa cell migration. Understanding of the mechanism through which p66Shc promotes migration may lead to the development of therapeutic strategies to treat metastatic CR PCa. Experimental Methods: Human prostate adenocarcinoma cell lines LNCaP C-33 and C-81, androgen-sensitive (AS) and androgen independent (AI) MDA PCa2b, PC-3, and DU145 were used to determine the role of p66Shc in PCa migration. Stable p66Shc cDNA transfected subclones S-31, S-32, and S-36 were established from LNCaP C-33 cells. p66Shc's impact on migration was determined using transwell migration assays. Immunoblotting was performed to profile potential proteins involved in the mechanism through which p66Shc influences migration. Small-molecule inhibitors were used to confirm these proteins’ involvement in migration. Results: Levels of p66Shc protein positively correlate with metastatic potential across multiple PCa cell lines as well as LNCaP and MDA call progressive models. p66Shc is an authentic oxidase and promotes ROS production. In this study, we further demonstrate peroxide treatment is able to induce C-33 cell migration in a dose-dependent manner, while antioxidants inhibit migration. Similarly, p66Shc subclones possess increased migratory ability which is abolished upon antioxidant treatment and demonstrates the involvement of ROS in p66Shc-mediated migration. Molecular profiling reveals the correlation of p66Shc protein level with the activation of ErbB-2, PYK2, AKT, ERK, p38, RAC1, STAT3, and STAT5 as well as suppression of cPAcP. Conclusions: Altogether, our results indicate p66Shc is involved in PCa cell migration, in part, by inducing ROS generation. Understanding the role p66Shc in advanced PCa progression will help to determine its potential as a therapeutic target, and elucidating its mechanism of intracellular signaling will enable us to design new treatments for metastatic CR PCa. Citation Format: Matthew A. Ingersoll, Sakthivel Muniyan, Fen-Fen Lin, Ta-Chun Yuan, Yu-Wei Chou, Surinder K. Batra, Ming-Fong Lin. p66Shc regulates the migration of castration-resistant prostate cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5069.

Many reported CuIn1-xGaxSe2 (CIGS) thin films for high-efficiency solar cells have been prepared via a two-stage process that consists of a high-vacuum film deposition step followed by selenization with excess H2Se gas or Se vapor. Removing toxic gas and high-vacuum requirements from this process would greatly simplify it and make it less hazardous. We report the formation of CuIn1-xGaxSe2 (x = 0, 0.25, 0.50, 0.75, 1.0) thin films achieved by rapid thermal annealing of spray-deposited CuIn1-xGaxS2 and Se in the absence of an additional selenium source. To prepare the Se layer, commercial Se powder was dissolved by refluxing in ethylenediamine/2,2-dimethylimidizolidine. After cooling to room temperature, this mixture was combined with 2-propanol and the resulting colloidal Se suspension was sprayed by airbrush onto a heated glass substrate. The resulting film was coated with nanocrystalline CuIn1-xGaxS2 via spray deposition of a toluene-based “nanoink” suspension. The two-layer sample was annealed at 550 oC in an argon atmosphere for 60 minutes to form the final CIGS product. Scanning electron microscopy images reveal that film grains are 200-300 nm in diameter and comparable to sizes of the reactant CuIn1-xGaxS2 nanoparticles. XRD patterns are consistent with the chalcopyrite unit cell and calculated lattice parameters and A1 phonon frequencies change nearly linearly between those for CuInSe2 and CuGaSe2.