Standard Treatment For Prostate Cancer Research Articles

Metformin in Overcoming Enzalutamide Resistance in Castration-Resistant Prostate Cancer.

Androgen deprivation is the standard treatment for prostate cancer (PCa) patients. However, the disease eventually progresses as castration-resistant PCa (CRPC). Enzalutamide, an AR inhibitor, is a typical drug to treating CRPC and due to continuous reliance on the drug, can lead to Enzalutamide-resistance (ENZ-r). This highlights the necessity for developing novel therapeutic targets to combat the gain of resistance. Metformin has been recently investigated for its potential anti-tumorigenic effects in many cancer types. In this study, we used enzalutamide and metformin in combination to explore the possible rescued efficacy of enzalutamide in the treatment of ENZ-r CRPC. We first tested the effects of this combination treatment on cell viability, drug synergy, and cell proliferation in ENZ-r CRPC cell lines. After combination treatment, we observed a decrease in cell proliferation and viability as well as a synergistic effect of both enzalutamide and metformin in vitro Following these results, we sought to explore how combination treatment effected mitochondrial fitness utilizing mitochondrial stress test analysis and mitochondrial membrane potential (MMP) shifts due to metformin's action in inhibiting Complex I of oxidative phosphorylation. We employed 2 different strategies of in vivo testing using 22Rv1 and LuCaP35CR xenograft models. Finally, RNA sequencing revealed a potential link in the downregulation of Ras/MAPK signaling following combination treatment. Significance Statement Increasing evidence suggests that oxidative phosphorylation might play a critical role in the development of resistance to cancer therapy. We showed that targeting oxidative phosphorylation with metformin can enhance the efficacy of enzalutamide in castration-resistant prostate cancer in vitro.

Abstract 253: Investigating key molecular players in putative stem cell subpopulations of prostate cancer

Abstract Background: Androgen deprivation therapy is the standard treatment for prostate cancer (PCa). Nevertheless, despite initial effectiveness, pre-existing cancer stem cell (CSC) populations invariably lead to incurable castration-resistant prostate cancer. CSCs are a subset of cancer cells possessing self-renewal properties, driving tumor progression and regrowth. CD44+ PCa cells exhibit more stemness features and are enriched in tumorigenic and metastatic progenitor cells. Here, we aim to explore different subpopulations in tumors based on levels of CD44 expression and investigate whether they have distinct molecular properties and functional characteristics. Material and Method: The number of CD44+ cells was evaluated in a tissue microarray from primary prostate cancer patient samples (EMPACT cohort) with clinical follow-up. Flow cytometry sorted the CRPC model LAPC9 tumor into CD44 high (CD44-H) and CD44 low (CD44-L) cells. RNA sequencing was performed on these subpopulations to explore their transcriptomic profiles. CD44 expression was validated at the cDNA and protein levels using qPCR and Western blot (WB) analysis. Sorted cells were maintained as organoids in vitro. To trace the dynamics of CD44-H and CD44-L subpopulations in vivo, LAPC9 tumor was labeled by fluorescent and luciferent markers. The CD44 status was determined by flow cytometry when tumor growth. Results: Patients with elevated expression of CD44 (higher number of CD44+ cells) at the time of surgery exhibited a greater propensity for clinic progression (5-year progression-free survival: 75% vs 95%, P=0.03). Furthermore, CD44-H cell ratio increased in the LAPC9 after castration, indicating that CD44-H cells can survive after treatment. Subsequent WB analysis confirmed that CD44 was highly expressed in sorted CD44-H cells, validating the flow cytometry results. Analysis of the CD44 RNA-seq data showed CD44 transcript variants CD44v10 (CD44-201) and CD44v7-10 (CD44-209) were notably upregulated in CD44-H cells. In organoid culture, sorted CD44-H cells displayed enhanced formation, indicating they possessed higher proliferative capacity and clonogenicity than CD44-L cells. Furthermore, when GFP-labeled CD44-H cells and RFP-labeled CD44-L cells were recombined in vivo, CD44-H cells exhibited robust proliferation, while CD44-L cells transitioned to a CD44hi state to facilitate tumor growth. Moreover, those GFP and RFP subpopulations displayed the same CD44hi cell ratio at the endpoint. Conclusion: Elevated CD44 expression is related to an increased risk in primary PCa. In addition, CD44-H cells exhibit high tumorigenicity in vitro and in vivo and can convert to each other. Moreover, the ratio of CD44-H cells in tumor at endpoint is consistent despite the starting CD44 expression status. Furthermore, the upregulation of CD44v10 and v7-10 in the CD44-H subpopulation may promote tumor formation and metastasis. Citation Format: Wanli Cheng, Marta De Menna, Francesco Bonollo, Panagiotis Chouvardas, George N. Thalmann, Sofia Karkampouna, Marianna Kruithof Julio. Investigating key molecular players in putative stem cell subpopulations of prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 253.

Electromagnetic Transmitter-Based Prostate Gating for Dose-Escalated Linac-Based Stereotactic Body Radiation Therapy: An Evaluation of Intrafraction Motion.

Stereotactic Body Radiotherapy (SBRT) is as a standard treatment for prostate cancer (PCa). Tight margins and high dose gradients are needed, and the precise localization of the target is mandatory. Our retrospective study reports our experience regarding the evaluation of intrafraction prostate motion during LINAC-based SBRT evaluated with a novel electromagnetic (EM) tracking device. This device consists of an integrated Foley catheter with a transmitter connected to a receiver placed on the treatment table. We analyzed 31 patients who received LINAC-based SBRT using flattening filter-free (FFF) volumetric modulated arc therapy (VMAT). The patients were scheduled to be treated for primary (n = 27) or an intraprostatic recurrent PCa (n = 4). A simulation CT scan was conducted while the patients had a filled bladder (100-150 cc) and an empty rectum, and an EM tracking device was used. The same rectal and bladder conditions were employed during the treatment. The patients received 36.25 Gy delivered over five consecutive fractions on the whole prostate and 40 Gy on the nodule(s) visible via MRI, both delivered with a Simultaneous Integrated Boost approach. The CTV-to-PTV margin was 2 mm for both the identified treatment volumes. Patient positioning was verified with XVI ConeBeam-CT (CBCT) matching before each fraction. When the signals exceeded a 2 mm threshold in any of the three spatial directions, the treatment was manually interrupted. A new XVI CBCT was performed if this offset lasted >20 s. We analyzed data about 155 fractions. The median and mean treatment times, calculated per fraction, were 10 m31 s and 12 m44 s (range: 6 m36 s-65 m28 s), and 95% of the fractions were delivered with a maximum time of 27 m48 s. During treatment delivery, the mean and median number of XVI CBCT operations realized during the treatment were 2 and 1 (range: 0-11). During the treatment, the prostate was outside the CTV-to-PTV margin (2 mm), thus necessitating the stoppage of the delivery +/- a reacquisition of the XVI CBCT for 11.2%, 8.9%, and 3.9% of the delivery time in the vertical, longitudinal, and lateral direction, respectively. We easily integrated an EM-transmitter-based gating for prostate LINAC-based SBRT into our normal daily workflow. Using this system, a 2 mm CTV-to-PTV margin could be safely applied. A small number of fractions showed a motion exceeding the predefined 2 mm threshold, which would have otherwise gone undetected without intrafraction motion management.

The SGLT2 inhibitor canagliflozin suppresses growth and enhances prostate cancer response to radiotherapy

Radiotherapy is a non-invasive standard treatment for prostate cancer (PC). However, PC develops radio-resistance, highlighting a need for agents to improve radiotherapy response. Canagliflozin, an inhibitor of sodium-glucose co-transporter-2, is approved for use in diabetes and heart failure, but is also shown to inhibit PC growth. However, whether canagliflozin can improve radiotherapy response in PC remains unknown. Here, we show that well-tolerated doses of canagliflozin suppress proliferation and survival of androgen-sensitive and insensitive human PC cells and tumors and sensitize them to radiotherapy. Canagliflozin blocks mitochondrial respiration, promotes AMPK activity, inhibits the MAPK and mTOR-p70S6k/4EBP1 pathways, activates cell cycle checkpoints, and inhibits proliferation in part through HIF-1α suppression. Canagliflozin mediates transcriptional reprogramming of several metabolic and survival pathways known to be regulated by ETS and E2F family transcription factors. Genes downregulated by canagliflozin are associated with poor PC prognosis. This study lays the groundwork for clinical investigation of canagliflozin in PC prevention and treatment in combination with radiotherapy.

Clostridium scindens metabolites trigger prostate cancer progression through androgen receptor signaling.

Prostate cancer (PCa) is one of the most common malignancies in men; recently, PCa-related mortality has increased worldwide. Although androgen deprivation therapy (ADT) is the standard treatment for PCa, patients often develop aggressive castration-resistant PCa (CRPC), indicating the presence of an alternative source of androgen. Clostridium scindens is a member of the gut microbiota and can convert cortisol to 11β-hydroxyandrostenedione (11β-OHA), which is a potent androgen precursor. However, the effect of C. scindens on PCa progression has not been determined. In this study, androgen-dependent PCa cells (LNCaP) were employed to investigate whether C. scindens-derived metabolites activate androgen receptor (AR), which is a pivotal step in the development of PCa. Results showed that cortisol metabolites derived from C. scindens-conditioned medium promoted proliferation and enhanced migration of PCa cells. Furthermore, cells treated with these metabolites presented activated AR and stimulated AR-regulated genes. These findings reveal that C. scindens has the potential to promote PCa progression via the activation of AR signaling. Further studies on the gut-prostate axis may help unravel an alternative source of androgen that triggers CRPC exacerbation.

Lymphatic Dissemination in Prostate Cancer: Features of the Transcriptomic Profile and Prognostic Models.

Radical prostatectomy is the gold standard treatment for prostate cancer (PCa); however, it does not always completely cure PCa, and patients often experience a recurrence of the disease. In addition, the clinical and pathological parameters used to assess the prognosis and choose further tactics for treating a patient are insufficiently informative and need to be supplemented with new markers. In this study, we performed RNA-Seq of PCa tissue samples, aimed at identifying potential prognostic markers at the level of gene expression and miRNAs associated with one of the key signs of cancer aggressiveness-lymphatic dissemination. The relative expression of candidate markers was validated by quantitative PCR, including an independent sample of patients based on archival material. Statistically significant results, derived from an independent set of samples, were confirmed for miR-148a-3p and miR-615-3p, as well as for the CST2, OCLN, and PCAT4 genes. Considering the obtained validation data, we also analyzed the predictive value of models based on various combinations of identified markers using algorithms based on machine learning. The highest predictive potential was shown for the "CST2 + OCLN + pT" model (AUC = 0.863) based on the CatBoost Classifier algorithm.

Determination of the potential of 5-Hydroxy-L-tryptophan and L-tryptophan as therapeutic agents for prostate cancer

Prostate cancer is the second leading cause of death from cancer in men. Androgen deprivation therapy (ADT) is used as the standard treatment for prostate cancer, and this treatment has undesirable side effects over time. There is a need for more effective, safe compounds that occur naturally under the influence of these undesirable limitations. In this study, the anti-cancer potentials of 5-Hydroxy-L-tryptophan (5-HTP) and L-tryptophan, which are thought to have various inhibitory potentials on cancer and its mechanisms, were studied. The study results showed that 5-HTP has a significant inhibition in prostate cancer cells. This study is an important preliminary screening for new and effective molecule trials. In order to develop a possible treatment strategy and to use these molecules as new therapeutic agents, further studies are needed in order to obtain more comprehensive data on the mechanisms of action of these molecules and to investigate their possible effects in other cancer types and the obtained data should be supported by these studies.

Relationship between prostate cancer and type 2 diabetes mellitus

Type 2 diabetes mellitus (DM2) and prostate cancer are widespread diseases throughout the world. Type II diabetes mellitus is accompanied by a deterioration in glycemic control, hyperinsulinemia, and insulin resistance (IR). The accumulation of glucose and lipids leads to a decrease in the density of insulin receptors and the development of insulin resistance in adipose tissue. This contributes to the development of hyperinsulinemia, which suppresses the breakdown of fat and leads to the progression of obesity. A vicious circle develops: insulin resistance → hyperinsulinemia → obesity → insulin resistance. Insulin influences the progression of the cell cycle, proliferation, and metastatic activity of the tumor. Recent studies have shown a strong direct correlation between fasting insulin levels and cancer mortality in men. This may be especially true in patients over 65, who are, in the first place, more likely to develop prostate cancer than younger patients. It should be noted that it is insulin, and not glucose, that is associated with the claim for the development of cancer. Hyperinsulinemia, which often occurs as a result of androgen deprivation therapy (ADT), the standard treatment for prostate cancer, is associated with a high tumor aggressiveness and faster treatment failure — the development of castrate-refractory prostate cancer. It is reasonable to assume that hyperinsulinemia — under whatever circumstances it is caused, whether due to ADT or due to inadequate nutrition and other lifestyle factors — can have the same negative effect on cellular signaling. Metabolic syndrome — essentially chronically elevated insulin levels — is closely associated with recurrence of cancer and worse post-treatment outcomes, which has led researchers to question generally accepted dietary guidelines for cancer patients, especially when they are undergoing treatment or recover from treatment, which may include recommendations to consume anything that will help maintain or restore body weight, regardless of sugar or carbohydrate content or its effect on insulin levels. A large number of patients live with hyperinsulinemia, but normoglycemia. Chronic hyperinsulinemia is the main driver of cardiometabolic disease, even when blood sugar levels are within reference values. The scale of this problem is not recognized by the medical and scientific community.

Analysis of Complications Development Predictors after Radical Prostatectomy

Introduction: The standard treatment for prostate cancer is radical prostatectomy (RP). This surgical technique results in typical complications such as intraoperative blood loss, urethral strictures (vesicourethral anastomosis), urinary incontinence, erectile dysfunction, lymphocele, and the ureter or rectum injury. The study aims to analyze the development of complications after radical prostatectomy.
 Materials and methods: The article presents a retrospective analysis of clinical cases with an established diagnosis of prostate cancer from 2012 to 2018 in Irkutsk, Russian Federation. During this period, 52 patients met the study criteria. A multivariate analysis established Non-Nerve-sparing RRP (OR-0.9; 95% CI-1.9; -0.07; p=0.035) as a significant incontinence predictor after 2 years.
 Results: Multivariate analysis also established previous transurethral operations as a significant predictor of the vesicourethral anastomosis stricture (OR 6.09; 95% CI 0.71; 11.4; p=0.026), which indicates a six times risk of developing a vesicourethral anastomosis stricture if the patient already had one or more transurethral surgery. Obesity (OR 0.12; 95% CI 0.03; 0.21; p = 0.008), diabetes (OR 2.3; 95% CI 0.45; 4.2; p = 0.015) and coagulopathy (OR 3.1; 95% CI 0.5; 5.7; p = 0.019) became independent predictors of lymphocele development.
 Conclusions: The study revealed some new information on the possible predictors of such complications as urinary incontinence in the late period, the lymphocele, and stricture of the vesicourethral anastomosis. Some of the results require further study and confirmation.

Machine Learning Predicts Outcomes of Phase III Clinical Trials for Prostate Cancer

The ability to predict the individual outcomes of clinical trials could support the development of tools for precision medicine and improve the efficiency of clinical-stage drug development. However, there are no published attempts to predict individual outcomes of clinical trials for cancer. We used machine learning (ML) to predict individual responses to a two-year course of bicalutamide, a standard treatment for prostate cancer, based on data from three Phase III clinical trials (n = 3653). We developed models that used a merged dataset from all three studies. The best performing models using merged data from all three studies had an accuracy of 76%. The performance of these models was confirmed by further modeling using a merged dataset from two of the three studies, and a separate study for testing. Together, our results indicate the feasibility of ML-based tools for predicting cancer treatment outcomes, with implications for precision oncology and improving the efficiency of clinical-stage drug development.

TRNALys-Derived Fragment Alleviates Cisplatin-Induced Apoptosis in Prostate Cancer Cells.

Cisplatin is a standard treatment for prostate cancer, which is the third leading cause of cancer-related deaths among men globally. However, patients who have undergone cisplatin can rxperience relapse. tRNA-derived fragments (tRFs) are small non-coding RNAs generated via tRNA cleavage; their physiological activities are linked to the development of human diseases. Specific tRFs, including tRF-315 derived from tRNALys, are highly expressed in prostate cancer patients. However, whether tRF-315 regulates prostate cancer cell proliferation or apoptosis is unclear. Herein, we confirmed that tRF-315 expression was higher in prostate cancer cells (LNCaP, DU145, and PC3) than in normal prostate cells. tRF-315 prevented cisplatin-induced apoptosis and alleviated cisplatin-induced mitochondrial dysfunction in LNCaP and DU145 cells. Moreover, transfection of tRF-315 inhibitor increased the expression of apoptotic pathway-related proteins in LNCaP and DU145 cells. Furthermore, tRF-315 targeted the tumor suppressor gene GADD45A, thus regulating the cell cycle, which was altered by cisplatin in LNCaP and DU145 cells. Thus, tRF-315 protects prostate cancer cells from mitochondrion-dependent apoptosis induced by cisplatin treatment.

Abstract 5499: Cell cycle-dependent, comprehensive mathematical modeling of the role of DNA repair in response to radiotherapy for prostate cancer

Abstract The purpose of this study is to develop a comprehensive mathematical model of DNA double-strand break (DSB) repair in a cell cycle-dependent manner to analyze the improved radiosensitivity of prostate cancer (PCa) cells to ionizing radiation (IR) when radiation treatment is combined with androgen deprivation therapy (ADT). The effectiveness of the combination treatment, which is currently a standard treatment for PCa, depend on DSB repair capacity of the cells as these are the main lesions following IR. It is reported in the literature that the major DSB repair pathways, non-homologous end joining (NHEJ) and homologous recombination (HR), are both impaired after ADT, which then resulted in increased radiosensitivity and better IR treatment outcomes in PCa. In our previous work, we have developed quantitative models for NHEJ and HR individually to analyze the mechanism of the effect of ADT on IR treatment outcomes through impaired repair dynamics. The present work combines these two models in a cell cycle-dependent manner in order to develop a comprehensive model to analyze the repair dynamics after IR only and IR+ADT treatments. NHEJ is the major pathway, whereas HR is restricted to S- or G2-phases of the cell cycle after DNA replication has been completed and we have incorporated the cell cycle dependent contributions of the NHEJ and HR models in our comprehensive model. The literature data used in the development of these previous models were from both in vitro experiments as well as clinical data from PCa patients. In our comprehensive model, we have used the data from the literature to determine the distribution of the initial DSBs for cells in different cell cycle phases as the damage depends on the cell cycle phase at the time of radiation. We have incorporated the data on the percent contributions of NHEJ and HR repair in different cell cycle phases into the model and calculated the repair outcomes from NHEJ and HR models according to these ratios. Cell cycle arrest is implemented in relation to the amount of remaining DSBs in each cell cycle phase after repair. Using the number of unrepaired DSBs, we have calculated the proportion of cells that would progress to the next cell cycle phase as well as the proportion for which the cell death mechanism is triggered. The simulation results showed that ADT combined with IR has enhanced the treatment outcome. The cell survival rate was lower for the combination treatment case (55.7% compared to 62.1 % of IR only case). The cell proliferation was also significantly slower (85-95h doubling time compared to 35-45h of IR only case). The results agreed well with the experimental data that showed 30h and 95.5 h of doubling times for IR only and IR+ADT treatment respectively. The comprehensive model outcomes show that impaired NHEJ and HR dynamics as a result of ADT have the potential to enhance the IR treatment outcomes for PCa patients. Citation Format: Mengdi Qian, Alexandru Almasan, Evren Gurkan-Cavusoglu. Cell cycle-dependent, comprehensive mathematical modeling of the role of DNA repair in response to radiotherapy for prostate cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5499.

Multicenter Retrospective Observational Research on the Outcome of Radical Radiation Therapy for Prostate Cancer with Metastases

Hormonal therapy is the standard treatment for prostate cancer with metastases, but the disease usually becomes castration-resistant several years later. Before prostate cancer becomes castration-resistant, irradiating both the prostate and metastases may increase the local control rate and decrease the distant metastasis rate. In this multi-center study, we investigated clinical outcome and toxicities of patients with prostate cancer with metastases in patients irradiated as the first-line treatment (group A) in comparison with those irradiated after acquiring resistance to hormonal therapy (group B). Between January 2005 and June 2018, 91 patients with prostate cancer with 1-10 bone and/or 1-10 lymph node metastases were treated by IMRT. The prescription doses were 30-74.8 Gy to metastatic lesions and 60-78 Gy to the prostate. Among them, 13 patients were irradiated with IMRT and proton. Seventy-two patients only had lymph nodes, 11 had only bone metastases, and 8 had both metastases. Median age was 68 years (range, 54–85 years) and median follow-up was 32 months (range, 3-138 months). Seventy patients were in group A and 21 patients were in group B. Overall survival (OS) and progression free survival (PFS) at 3 years were 92% and 81%, respectively. At 3 years distant metastasis-free (DMF) rate were 82% in 73 patients and the local control rate of irradiated lymph nodes and bone metastases were 96% in 61 patients. Late Grade 2 or higher radiation genitourinary toxicities were seen in 2/91 and radiation gastrointestinal bleedings were observed in 4/91. No other Grade 2 or higher toxicities were seen. All genitourinary toxicities were Grade 2. At 3 years, OS was 95% versus 81%, PFS was 90% versus 51%, DMF rate was 90% versus 55% and the local control rate of irradiated lymph nodes and bone metastases was 100% versus 81% in groups A and B, respectively (log-rank P= 0.1, 0.00003, 0.002 and 0.009, respectively). The median of PSA doubling time (DT), which was calculated between the day of PSA nadir and the last follow-up date, was 5 months in 37 evaluable patients. The PSA failure was more frequently seen in the group with PSA DT < 10 months (n=20) than in the groups with stable PSA group (n=8) and with PSA DT ≥ 10 months (n=9) (P = 0.0017). To irradiate both the prostate and metastases before prostate cancer becomes castration-resistant may increase PFS, DMF, and the local control rate of irradiated lymph nodes and bone metastases from prostate cancer and decrease distant metastases rate.

Abstract 686: Quantitative analysis of the role of homologous recombination in response to radiotherapy for prostate cancer

Abstract The purpose of this study is to computationally analyze how the interaction between androgen receptor (AR) and homologous recombination (HR) affects the treatment outcome for ionizing radiation (IR) combined with androgen deprivation therapy (ADT) for prostate cancer (PCa). Combination treatment with radiation and ADT is currently a standard treatment for PCa. The effectiveness of radiation treatment alone depends on the cells’ capacity to repair the damage that is mostly in the form of double-strand breaks (DSBs). Two major pathways that repair DSBs are non-homologous end joining (NHEJ) and HR. The experimental data in the literature show that AR promotes both NHEJ and HR following IR, and inhibition of AR by ADT impairs both of these pathways in PCa cells leading to either increased radiosensitivity or sensitization to PARP inhibitors. In our previous work, we developed mathematical models of the NHEJ pathway and in this current work we have developed such models for HR to comprehensively analyze the response of PCa cells to IR combined with ADT. We have modeled HR using a series of ordinary differential equations. The parameters that needed to be estimated are the kinetic rate constants, and we have used least square estimation to obtain these model parameters. The data sets used in the parameter estimation were obtained from the literature and they were from both in vitro experiments as well as clinical data from PCa patients. The experimental data show that AR influences the DNA end resection that is required for proficient HR and we have computationally included this effect in the kinetics of the models. We have developed models for IR treatment alone or in combination with ADT. We have carried out sensitivity analysis and identifiability tests on all the parameters from both models in order to determine the parameters that are reliably estimated. The outputs from both NHEJ and HR models show that the suppression of AR activity through ADT has the potential to enhance the IR treatment outcomes for PCa patients. The impairment of HR by ADT also opens up an avenue for achieving synthetic lethality using PARP inhibitors as shown in the literature; in the future we are planning to extend our modeling efforts to include the effect of PARP inhibitors on the treatment outcome. Citation Format: Mengdi Qian, Alexandru Almasan, Evren Gürkan-Çavusoglu. Quantitative analysis of the role of homologous recombination in response to radiotherapy for prostate cancer [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 686.

Impact of high-dose vitamin d supplementation on short physical performance battery and bioelectrical impedance analysis in older patients with prostate cancer on ADT.

e23106 Background: Androgen deprivation therapy (ADT) is standard treatment for prostate cancer but may cause changes in body composition that lead to decreased physical function. Low vitamin D status is also associated with decreased functionality. The Short Physical Performance Battery (SPPB) is an objective assessment tool for evaluating functionality. The bioelectrical impedance analysis (BIA) is a portable tool for assessing lean mass and phase angle, a measure of nutrition status and frailty in chronic disease. Methods: This was a secondary analysis of a randomized controlled trial to assess the impact of high dose vitamin D in older patients (≥60 yrs) with prostate cancer on ADT. Patients with prostate cancer (N = 59, age 67.6 ± 5.4) with vitamin D insufficiency ( &lt; 32 ng/ml) were randomized to high-dose vitamin D (n = 29, 600 IU/daily plus 50,000 IU/weekly) or low-dose vitamin D (n = 30, 600 IU/daily plus placebo weekly) for 24 weeks. SPPB tests and BIA were assessed at baseline, 12 weeks and 24 weeks. Phase angle values were calculated using atan(reactance/resistance) x (180°/π). A phase angle value &lt; 5.7° is a valid cutoff for frailty in older men. Results: Serum analyses showed compliance with vitamin D intake (25-OH vitamin D change: high vitamin D = +32.0 ng/ml vs low dose RDA vitamin D = +4.3 ng/ml; p &lt; .01). There were no difference at all three assessments for SPPB or lean mass between arms. The high-dose vitamin D group had wider phase angle values at 12 weeks (5.81º vs. 5.32º; p = .018) and 24 weeks (5.89º vs. 5.40º; p = .030). The low-dose group had phase angle values &lt; 5.7º over the course of the study. At baseline, over 18% of patients had phase angle values below the 10th percentile of the general population matched on age and BMI. As vitamin D levels increased throughout the study, fewer patients fell below the 10th percentile. Conclusions: The high-dose vitamin D group maintained wider phase angle values over 24 weeks, while phase angle for the low-dose group decreased from baseline. High-dose vitamin D supplementation may impact factors related to phase angle and frailty in patients receiving ADT. Funding: NCI UGCA189961, R21CA175793, K07CA168911, and GR501293.

Abstract B060: Molecular characterization of cancer stem cells from patient-derived xenografts of advanced prostate cancer

Abstract Introduction: Androgen-deprivation therapy is the standard treatment for prostate cancer. Despite the initial response, a fraction of cases manifest progression to castration-resistant prostate cancer. The paradigm of PCa recurrence is the existence of androgen-independent cancer stem cells, which differentiate into androgen-dependent cancer cells that reinitiate tumor growth. The phenotypic properties of cancer stem cells versus highly proliferative progenitor cells/facultative stem cells remain to be further characterized in terms of androgen receptor signaling, quiescence/proliferation, tumorigenicity, and therapy resistance. Methods: To address the molecular basis of CSC switch from androgen-dependency to independency we have employed two patient-derived xenograft models (LAPC-9 and BM-18) that have different androgen sensitivity properties. We have performed microarray and proteomic analysis of BM-18 tumor tissues prior to and following castration as well as androgen replacement. To characterize the cancer stem cells in these models we have isolated different subpopulations based on combination of selected markers and assessed the transcriptomic changes, proteomic profile, and in vivo self-renewal. Results: Castration induces a rapid tumor volume decrease in the BM-18 and a stabilization of tumor burden in the LAPC-9, reflecting different androgen-dependent cell states. Proteomic analysis of bulk BM-18 tumors (intact, 14 days post castration, 50 days post androgen replacement) indicates an enrichment of stem cell markers upon castration; CD44, NKX3.1, and ALDH1 isoforms. Microarray analysis has confirmed upregulation of CD44 and ALDH1A1 at castrated state, and downregulation of expression upon androgen replacement at early time points (24 hours). We have isolated CD44+/-ALDHhigh/low subpopulation by flow cytometry and analyzed their transcriptome and proteomic changes. Castration in the BM-18 model induces an increase in the subpopulations of CD44+/ALDHlow (from 0.44% to 2.3%) and CD44+/ALDHhigh (from 0.06% to 0.38%). However, the same subpopulations are decreased in the LAPC-9 model upon castration, while only the CD44-/ALDHhigh subset is enriched (from 3.5% to 7.1%). Conclusions: Different androgen-independent cancer stem cell subpopulations may be distinguished by the ALDH activity status in combination with CD44. The androgen-independent cells in the BM-18 androgen-dependent model are reflected by enrichment of CD44 expression, as well as a rare double positive population. In the androgen-independent LAPC-9 model, CD44 expression is contrastingly decreased, potentially reflecting androgen-dependent CD44+ cells, and ALDH activity increased in CD44- cells. Ongoing analysis may elucidate the molecular mechanisms controlling the different cancer stem cell fates and their androgen sensitivity. Cancer stem cell potential of the different cell populations will have to be elucidated by transplantation experiments. Citation Format: Sofia Karkampouna, Marta de Menna, Markus Germann, Jöel Grosjean, Peter C. Gray, George N. Thalmann, Marianna Kruithof-de Julio. Molecular characterization of cancer stem cells from patient-derived xenografts of advanced prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr B060.

Suppression of ribosomal protein RPS6KB1 by Nexrutine increases sensitivity of prostate tumors to radiation

Radiation therapy (XRT) is a standard treatment for prostate cancer (PCa). Although dose escalation increases local control, toxicity hampers further escalation. Broader improvement will be possible by the addition of adjuvant therapies, which can synergize with radiation and thus improve efficacy. We have identified a natural compound (Nexrutine, Nx) that inhibits the survival and growth of PCa cells in combination with radiation. Combination studies demonstrated strong interaction between Nx and radiation both in vitro in multiple PCa cell lines and in the Transgenic adenocarcinoma of mouse prostate (TRAMP) model. Nx potentiated growth inhibitory effects of IR by down regulating ribosomal protein S6K (RPS6KB1), CyclinD1, Chk1 and HIF-1 α and prolonging G2/M checkpoint block. RPS6KB1 is upregulated in prostate cancers and its expression is correlated with tumor grade. Knockdown of RPS6KB1 in PCa cells increased their sensitivity toward radiation-induced survival inhibition. Overall, we provide scientific evidence (i) in support of Nx as an adjuvant in PCa patients receiving XRT (ii) suggesting that RPS6KB1 is an important player in Nx-mediated combinatorial benefits and emphasizes that RPS6KB1 is a novel target for PCa treatment. These data underscore the need to test the agent in additional preclinical models to validate these observations.

Abstract 3053: Characterization of cancer stem cell subpopulations from patient-derived xenografts of advanced prostate cancer

Abstract Androgen-deprivation therapy is the standard treatment for prostate cancer. Despite the initial response, a fraction of cases manifest progression to castration-resistant prostate cancer. PCa recurrence is possibly due to androgen-independent cancer stem cells that reinitiate tumor growth. The properties of cancer stem cells versus highly proliferative progenitor cells remain to be further characterized at the cellular and gene expression level. To address the molecular basis of CSC switch from androgen dependency to independence, we have employed patient-derived xenograft models (LAPC-9 and BM-18) that have different androgen sensitivity properties. We have performed microarray and proteomic analysis of BM-18 tumor tissues prior to and following castration as well as androgen replacement. To characterize the cancer stem cells in these models we have isolated different subpopulations by FACS cytometry, based on combination of selected markers (CD44 and ALDH activity measured by ALDELFUOR assay) aiming to assess the transcriptomic profile of these different populations. To assess response of these CD44+/-/ALDH+/- cells to androgen targeting compounds we have established an androgen-sensitive xenograft model (PNPCa) and tested it by ex vivo tissue culture and organoid viability assays. Proteomic and microarray analysis of bulk BM-18 tumors indicates enrichment of stem cell markers upon castration: CD44, NKX3.1 and ALDH1 isoforms. Readministration of testosterone induces decrease of these markers. Castration induces a rapid tumor volume decrease in the BM-18 as opposed to LAPC-9, reflecting different androgen-dependent cell states. CD44+/-/ALDHhigh/low subpopulations were isolated by flow cytometry and for transcriptomic analysis. Castration in the BM18 model induces an increase in the subpopulations of CD44+/ALDHlow and CD44+/ALDHhigh, while ALDHsingle and ALDHhigh total populations are decreased. Both CD44 expression and ALDH activity is increased in the LAPC-9 model upon castration. Treatment of PNPCa tumor parts ex vivo with enzalutamide inhibited expression of androgen receptor and keratin 8 expression. CD44+ organoids derived from the same tissue did not show altered viability after enzalutamide treatment. Different androgen-independent cancer stem cell populations may be distinguished by ALDH activity status and CD44. Androgen-independent cells in the BM-18 androgen-dependent model are reflected by enrichment of CD44 expression. The least abundant subpopulation CD44+/ALDHhigh is present in the LAPC-9 and expanded upon castration, while in the BM-18 model it is exclusively present after castration, reflecting different androgen sensitivity. Ongoing analysis may elucidate the molecular mechanisms controlling cancer stem cell fates, androgen sensitivity and drug resistance. Citation Format: Sofia Karkampouna, Marta De Menna, Markus Germann, Joel Grosjean, Peter Clark Gray, George Niklaus Thalmann, Marianna Kruithof-de Julio. Characterization of cancer stem cell subpopulations from patient-derived xenografts of advanced prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3053.

The novel role of IL-37 in prostate cancer: evidence as a promising radiosensitizer.

Prostate cancer (PCa) is the most common non-cutaneous cancer in men in the USA. Radiation therapy (RT) is widely considered the standard treatment for PCa. IL-37 is an IL-1 family member, and it has been extensively studied in immunity. However, no studies have been done regarding its potential as a radiosensitizer. This study is designed to investigate the direct effect of IL-37 on growth of DU145 and PC-3, two widely studied PCa cell lines, and to investigate whether IL-37 could be used as a radiosensitizer for PCa. Clonogenic survival and quick cell proliferation assays along with immunohistochemistry, TUNEL staining, and caspace-3 activity assay kits as well as RT-PCR were used in this study. Our results showed that IL-37 has little direct effect on growth of PCa. However, IL-37/RT enhanced RT-induced inhibition of cell proliferation and apoptosis in both cell lines. We further found that IL-37/RT upregulated the mRNA expression of p27, Fas, and Bax, while downregulating the mRNA expression of cdk2 in DU145 cells. These findings suggest that IL-37 has the potential to be used as a radiosensitizer for PCa and warrants further investigation.

Involvement of aberrantly activated HOTAIR/EZH2/miR-193a feedback loop in progression of prostate cancer

BackgroundThough androgen deprivation therapy is the standard treatment for prostate cancer (PCa), most patients would inevitably progress to castration-resistant prostate cancer (CRPC) which is the main cause of PCa death. Therefore, the identification of novel molecular mechanism regulating cancer progression and achievement of new insight into target therapy would be necessary for improving the benefits of PCa patients. This study aims to study the function and regulatory mechanism of HOTAIR/EZH2/miR-193a feedback loop in PCa progression.MethodsMSKCC and TCGA datasets were used to identify miR-193a expression profile in PCa. Cell Counting Kit-8 (CCK-8) assays, colony formation, invasion, migration, flow cytometry, a xenograft model and Gene Set Enrichment Analysis were used to detect and analyze the biological function of miR-193a. Then, we assessed the role of HOTAIR and EZH2 in regulation of miR-193a expression by using plasmid, lentivirus and small interfering RNA (siRNA). Luciferase reporter assays and chromatin immunoprecipitation assays were performed to detect the transcriptional activation of miR-193a by EZH2 and HOTAIR. Further, qRT-PCR and luciferase reporter assays were conducted to examine the regulatory role of miR-193a controlling the HOTAIR expression in PCa. Finally, the correlation between HOTAIR, EZH2 and miR-193a expression were analyzed using In situ hybridization and immunohistochemistry.ResultsWe found that miR-193a was significantly downregulated in metastatic PCa through mining MSKCC and TCGA datasets. In vitro studies revealed that miR-193a inhibited PCa cell growth, suppressed migration and invasion, and promoted apoptosis; in vivo results demonstrated that overexpression of miR-193a mediated by lentivirus dramatically reduced PCa xenograft tumor growth. Importantly, we found EZH2 coupled with HOTAIR to repress miR-193a expression through trimethylation of H3K27 at miR-193a promoter in PC3 and DU145 cells. Interestingly, further evidence illustrated that miR-193a directly targets HOTAIR showing as significantly reduced HOTAIR level in miR-193a overexpressed cells and tissues. The expression level of miR-193a was inversely associated with that of HOTAIR and EZH2 in PCa.ConclusionThis study firstly demonstrated that miR-193a acted as tumor suppressor in CRPC and the autoregulatory feedback loop of HOTAIR/EZH2/miR-193a served an important mechanism in PCa development. Targeting this aberrantly activated feedback loop may provide a potential therapeutic strategy.