Doublecortin-like kinase 1 is a therapeutic target in squamous cell carcinoma

Doublecortin like kinase 1 (DCLK1) plays a crucial role in several cancers including colon and pancreatic adenocarcinomas. However, its role in squamous cell carcinoma (SCC) remains unknown. To this end, we examined DCLK1 expression in head and neck SCC (HNSCC) and anal SCC (ASCC). We found that DCLK1 is elevated in patient SCC tissue, which correlated with cancer progression and poorer overall survival. Furthermore, DCLK1 expression is significantly elevated in human papilloma virus negative HNSCC, which are typically aggressive with poor responses to therapy. To understand the role of DCLK1 in tumorigenesis, we used specific shRNA to suppress DCLK1 expression. This significantly reduced tumor growth, spheroid formation, and migration of HNSCC cancer cells. To further the translational relevance of our studies, we sought to identify a selective DCLK1 inhibitor. Current attempts to target DCLK1 using pharmacologic approaches have relied on nonspecific suppression of DCLK1 kinase activity. Here, we demonstrate that DiFiD (3,5-bis [2,4-difluorobenzylidene]-4-piperidone) binds to DCLK1 with high selectivity. Moreover, DiFiD mediated suppression of DCLK1 led to G2/M arrest and apoptosis and significantly suppressed tumor growth of HNSCC xenografts and ASCC patient derived xenografts, supporting that DCLK1 is critical for SCC growth.

Abstract 2419: Understanding the role of DCLK1 mediated invadopodia regulation in HNSCC

Despite therapeutic advances, head and neck squamous cell carcinoma (HNSCC) is marked by high mortality, particularly with increasing stage. Locoregional invasion, an early step in metastasis, is driven by the development of finger-like processes on the tumor cell known as invadopodia. Mature, active invadopodia secrete matrix metalloproteases (MMP) that enable extension of the cell into the extracellular matrix (ECM). Kinesins haul RAB-bound vesicles containing MMPs along microtubules the length of invadopodia for secretion to the most distal aspect of the invadopodia. It is unclear how these kinesins are modulated within invadopodia. In preliminary studies on patient samples, we identified high levels of doublecortin like kinase (DCLK1) at the invasive front of HNSCC. We hypothesize DCLK1 supports the function of kinesins as a mechanism of invasion. DCKL1 was knocked down in HNSCC lines with a short hairpin RNA (shDCLK1). Invasion and migration assays were performed in shDCLK1 and shcontrol tumor cells by utilizing a transwell assay. Confocal microscopy using Leica LAS X, was performed to assess colocalization of DCLK1 and markers of mature invadopodia (cortactin, TKS5, MT1-MMP) in HNSCC lines for. . To validate the association of DCLK1 with Kif16B and RAB40b, we carried out a co-immunoprecipitation analysis. Finally, conditioned media from shDCLK1 and shControl HNSCC cells was used to assess MMP activity using gelatin zymography and MMP profiler arrays. Transwell assay demonstrates reduced movement in shDCLK1 compared to shcontrol tumor cells (p <0.0001 invasion, p <0.001 migration). Confocal microscopy shows colocalization of MMP 9 and DCLK1 to invadopodia. DCLK1 immunoprecipitation show RAB40b and Kif16b complex together. Additionally, DCLK1, RAB40b, and Kif16b colocalize to invadopodia in confocal studies. We found that DCLK1 colocalizes with markers of mature invadopodia, and that DCLK1 colocalizes to Rab40b, Kif16b, and MMP9 within invadopodia. DCLK1 and MMP9 co-localize to invadopodia as well. Cells expressing DCLK1 had increased MMP 1, and 9 (p <0.041, p <0.001) expression compared to shDCLK1 cells. Further, shDCLK1 cells have significantly attenuated MMP 1 and 9 activity as measured by gelatin zymography. These studies reveal a novel role of DCLK1 in the molecular mechanism driving invadopodia, MMP trafficking and signaling. These early studies indicate that targeting DCLK1 in HNSCC may reduce locoregional invasion and help prevent early metastatic spread.

Citation Format: Levi K. Arnold, David Standing, Prabhu Ramamoorthy, Harmony Saunders, Thuc Ly, Shrikant Anant, Sufi Thomas. Understanding the role of DCLK1 mediated invadopodia regulation in HNSCC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2419.

Whole lung Irradiation as a Novel treatment for COVID-19: Final Results of the Prospective Randomized trial (WINCOVID trial)

Background and purpose

The ability of low dose radiotherapy (LDRT) to control the unprecedented cytokine release associated with COVID-19 pathogenesis has been an area of widespread research since the COVID pandemic. It has not been studied adequately whether the anti-inflammatory effect of LDRT provides additional benefit when used concurrently with steroids amongst other standard pharmacologic therapy.

Material and methods

51 RT-PCR positive COVID-19 patients were recruited between November 2020 and July 2021. 34 patients were allotted to receive 0.5 Gy single session LDRT along with standard pharmacologic therapy while 17 patients received standard pharmacologic therapy alone. All had SpO₂ <94% on room air, respiratory frequency >24/min and SpO₂/FiO₂ (SF) ratio between >89 but <357. All patients underwent a baseline CT scan. They were followed up for 28 days during when serial SF ratio, blood biomarkers (CRP, Serum ferritin, IL-6), Absolute lymphocyte count (ALC), repeat CT scan were performed at pre-defined time points.

Results

LDRT showed a statistically significant early improvement in oxygenation, an early time to clinical recovery, early hospital discharge and better radiological resolution compared to control group. There was no statistically significant difference between the two groups with respect to ALC or blood biomarkers at any of the measured time points. The 28-day mortality rate did not show statistically significant difference between the two groups.

Conclusion

LDRT can be considered for selected oxygen-dependent moderate to severe COVID-19 patients for rapid relief of respiratory distress. It can be safely combined with standard pharmacologic treatment in such patients for added clinical benefit.

Whole lung irradiation as a novel treatment for COVID-19: Interim results of an ongoing phase 2 trial in India

Background and purpose

The main cause of death in COVID-19 pneumonia is acute respiratory distress syndrome which is preceded by massive cytokine release. Low-dose radiation therapy (LDRT) has anti-inflammatory and immunomodulatory effects that can interfere with the inflammatory cascade, reducing the severity of associated cytokine release.

Material & methods

25 patients with RT-PCR proven COVID-19 pneumonia were enrolled between November 2020 and May 2021. All patients had SpO2 < 94 % on room air, respiratory frequency > 24/min and SpO2/FiO2 ratio (SF ratio) of >89 but <357. Patients were treated according to standard COVID-19 management guidelines along with single fraction LDRT of 0.5 Gy to bilateral whole lungs within 10 days of symptom onset and 5 days of hospital admission.

Results

LDRT was well tolerated by all patients. There was a statistically significant improvement in oxygenation as given by the SF ratio between pre-RT and day 2 (p < 0.05), day 3 (p < 0.001) and day 7 (p < 0.001) post RT. Demand for supplemental oxygen showed statistically significant reduction between pre-RT and day 2 (p < 0.05), day 3 (p < 0.001), day 7 (p < 0.001) post RT. 88 % patients attained clinical recovery within 10 days post LDRT and median time to hospital discharge from day of LDRT was 6 days. Three patients deteriorated and died.

Conclusion

As per our initial experience, LDRT appears to be a promising modality of treatment with rapid relief of respiratory distress in selected patients with moderate to severe COVID-19 pneumonia. This translates to early clinical recovery and hospital discharge in the selected patient group.

Metabolomics Insights in Early Childhood Caries

Dental caries is characterized by a dysbiotic shift at the biofilm-tooth surface interface, yet comprehensive biochemical characterizations of the biofilm are scant. We used metabolomics to identify biochemical features of the supragingival biofilm associated with early childhood caries (ECC) prevalence and severity. The study's analytical sample comprised 289 children ages 3 to 5 (51% with ECC) who attended public preschools in North Carolina and were enrolled in a community-based cross-sectional study of early childhood oral health. Clinical examinations were conducted by calibrated examiners in community locations using International Caries Detection and Classification System (ICDAS) criteria. Supragingival plaque collected from the facial/buccal surfaces of all primary teeth in the upper-left quadrant was analyzed using ultra-performance liquid chromatography-tandem mass spectrometry. Associations between individual metabolites and 18 clinical traits (based on different ECC definitions and sets of tooth surfaces) were quantified using Brownian distance correlations (dCor) and linear regression modeling of log₂-transformed values, applying a false discovery rate multiple testing correction. A tree-based pipeline optimization tool (TPOT)-machine learning process was used to identify the best-fitting ECC classification metabolite model. There were 503 named metabolites identified, including microbial, host, and exogenous biochemicals. Most significant ECC-metabolite associations were positive (i.e., upregulations/enrichments). The localized ECC case definition (ICDAS ≥1 caries experience within the surfaces from which plaque was collected) had the strongest correlation with the metabolome (dCor P = 8 × 10^-3). Sixteen metabolites were significantly associated with ECC after multiple testing correction, including fucose (P = 3.0 × 10^-6) and N-acetylneuraminate (p = 6.8 × 10^-6) with higher ECC prevalence, as well as catechin (P = 4.7 × 10^-6) and epicatechin (P = 2.9 × 10^-6) with lower. Catechin, epicatechin, imidazole propionate, fucose, 9,10-DiHOME, and N-acetylneuraminate were among the top 15 metabolites in terms of ECC classification importance in the automated TPOT model. These supragingival biofilm metabolite findings provide novel insights in ECC biology and can serve as the basis for the development of measures of disease activity or risk assessment.

Abstract 6405: Fosciclopirox suppresses growth of high-grade urothelial cancer by targeting Notch signaling

Ciclopirox (CPX) is a FDA-approved topical antifungal agent that has demonstrated preclinical anticancer activity in solid and hematologic malignancies. It's clinical utility as an anticancer agent, however, is limited by poor oral bioavailability, gastrointestinal toxicity, and poor water solubility. Fosciclopirox, the phosphoryloxymethyl ester of CPX (Ciclopirox Prodrug, CPX-POM), is rapidly and completely metabolized to CPX, the active metabolite, which subsequently undergoes renal elimination resulting in urine concentrations of CPX that exceed in vitro IC50's several-fold. We characterized the activity of CPX-POM and its major metabolites in vitro utilizing authenticated human T24, HT-1376, and UM-UC-3 high-grade urothelial cancer cell lines. CPX inhibited cell proliferation, clonogenicity, and spheroid formation, and increased cell cycle arrest at S and G0/G1 phases. Mechanistically, CPX suppressed activation of Notch signaling, which was partially rescued by ectopic expression of the intracellular domain of Notch1. Molecular modeling and cellular thermal shift assays demonstrated CPX binding to γ-secretase complex proteins Presenilin1 and Nicastrin, which are essential for Notch activation. Interrogation of The Cancer Genome Atlas (TCGA) database demonstrated that both proteins were upregulated in bladder tumor tissue, and that higher levels of Presenilin1 and Nicastrin were significantly associated with lower overall survival in muscle invasive bladder cancer (MIBC) patients. To establish in vivo preclinical proof of principle, we tested fosciclopirox in the validated N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) mouse bladder cancer model in two separate studies. Intraperitoneal (IP) administration of CPX-POM once daily for four weeks at doses ranging from 25 to 200 mg/kg significantly decreased bladder weight and resulted in a migration to lower stage tumors in CPX-POM treated animals compared to untreated animals. This was coupled with a reduction in proliferation index, as well as reductions in Presenilin1 and Hey1 expression in bladder tumor tissues in CPX-POM treated animals. A similar anti-tumor response was observed following once daily versus three times weekly IP CPX-POM in this chemical carcinogen mouse model of bladder cancer. The safety, dose tolerance, pharmacokinetics and pharmacodynamics of intravenous (IV) CPX-POM were characterized in a US multi-center, First-in-Human, Phase 1, open-label, dose escalation study (NCT03348514). Eight cohorts of 19 patients received IV CPX-POM doses ranging from 30 to 1200 mg/m2 for as many as six 21-day treatment cycles. Adequate systemic and urinary tract CPX exposures were achieved at the maximum tolerated dose of 900 mg/m2 with evidence of Notch inhibition. An expansion cohort study in 12 cisplatin-ineligible MIBC patients receiving two treatment cycles of CPX-POM prior to radical cystectomy (RC) is underway. Evidence of pharmacologic activity is being characterized in bladder tumor tissues obtained at RC.

Citation Format: Scott James Weir, Prasad Dandawate, Prabhu Ramamoorthy, Parthasarathy Ranjarajan, Robyn Wood, Amanda Brinker, Benjamin Woolbright, Mehmet Tanol, Tammy Ham, William McCulloch, Michael Dalton, Michael J. Baltezor, Roy A. Jensen, John A. Taylor, Shrikant Anant. Fosciclopirox suppresses growth of high-grade urothelial cancer by targeting Notch signaling [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 6405.

Diphenylbutylpiperidine Antipsychotic Drugs Inhibit Prolactin Receptor Signaling to Reduce Growth of Pancreatic Ductal Adenocarcinoma in Mice

BACKGROUND & AIMS

Prolactin (PRL) signaling is up-regulated in hormone-responsive cancers. The PRL receptor (PRLR) is a class I cytokine receptor that signals via the Janus kinase (JAK)-signal transducer and activator of transcription and mitogen-activated protein kinase pathways to regulate cell proliferation, migration, stem cell features, and apoptosis. Patients with pancreatic ductal adenocarcinoma (PDAC) have high plasma levels of PRL. We investigated whether PRLR signaling contributes to the growth of pancreatic tumors in mice.

METHODS

We used immunohistochemical analyses to compare levels of PRL and PRLR in multitumor tissue microarrays. We used structure-based virtual screening and fragment-based drug discovery to identify compounds likely to bind PRLR and interfere with its signaling. Human pancreatic cell lines (AsPC-1, BxPC-3, Panc-1, and MiaPaCa-2), with or without knockdown of PRLR (clustered regularly interspaced short palindromic repeats or small hairpin RNA), were incubated with PRL or penfluridol and analyzed in proliferation and spheroid formation. C57BL/6 mice were given injections of UNKC-6141 cells, with or without knockdown of PRLR, into pancreas, and tumor development was monitored for 4 weeks, with some mice receiving penfluridol treatment for 21 days. Human pancreatic tumor tissues were implanted into interscapular fat pads of NSG mice, and mice were given injections of penfluridol daily for 28 days. Nude mice were given injections of Panc-1 cells, xenograft tumors were grown for 2 weeks, and mice were then given intraperitoneal penfluridol for 35 days. Tumors were collected from mice and analyzed by histology, immunohistochemistry, and immunoblots.

RESULTS

Levels of PRLR were increased in PDAC compared with nontumor pancreatic tissues. Incubation of pancreatic cell lines with PRL activated signaling via JAK2-signal transducer and activator of transcription 3 and extracellular signal-regulated kinase, as well as formation of pancospheres and cell migration; these activities were not observed in cells with PRLR knockdown. Pancreatic cancer cells with PRLR knockdown formed significantly smaller tumors in mice. We identified several diphenylbutylpiperidine-class antipsychotic drugs as agents that decreased PRL-induced JAK2 signaling; incubation of pancreatic cancer cells with these compounds reduced their proliferation and formation of panco spheres. Injections of 1 of these compounds, penfluridol, slowed the growth of xenograft tumors in the different mouse models, reducing proliferation and inducing autophagy of the tumor cells.

CONCLUSIONS

Levels of PRLR are increased in PDAC, and exposure to PRL increases proliferation and migration of pancreatic cancer cells. Antipsychotic drugs, such as penfluridol, block PRL signaling in pancreatic cancer cells to reduce their proliferation, induce autophagy, and slow the growth of xenograft tumors in mice. These drugs might be tested in patients with PDAC.

Suppressing STAT5 signaling affects osteosarcoma growth and stemness

Osteosarcoma (OS) is the most common primary bone tumor that primarily affects children and adolescents. Studies suggested that dysregulation JAK/STAT signaling promotes the development of OS. Cells treated with pimozide, a STAT5 inhibitor suppressed proliferation and colony formation and induced sub G0/G1 cell cycle arrest and apoptosis. There was a reduction in cyclin D1 and CDK2 expression and Rb phosphorylation, and activation of Caspase-3 and PARP cleavage. In addition, pimozide suppressed the formation of 3-dimensional osteospheres and growth of the cells in the Tumor in a Dish lung organoid system. Furthermore, there was a reduction in expression of cancer stem cell marker proteins DCLK1, CD44, CD133, Oct-4, and ABCG2. More importantly, it was the short form of DCLK1 that was upregulated in osteospheres, which was suppressed in response to pimozide. We further confirmed by flow cytometry a reduction in DCLK1+ cells. Moreover, pimozide inhibits the phosphorylation of STAT5, STAT3, and ERK in OS cells. Molecular docking studies suggest that pimozide interacts with STAT5A and STAT5B with binding energies of −8.4 and −6.4 Kcal/mol, respectively. Binding was confirmed by cellular thermal shift assay. To further understand the role of STAT5, we knocked down the two isoforms using specific siRNAs. While knockdown of the proteins did not affect the cells, knockdown of STAT5B reduced pimozide-induced necrosis and further enhanced late apoptosis. To determine the effect of pimozide on tumor growth in vivo, we administered pimozide intraperitoneally at a dose of 10 mg/kg BW every day for 21 days in mice carrying KHOS/NP tumor xenografts. Pimozide treatment significantly suppressed xenograft growth. Western blot and immunohistochemistry analyses also demonstrated significant inhibition of stem cell marker proteins. Together, these data suggest that pimozide treatment suppresses OS growth by targeting both proliferating cells and stem cells at least in part by inhibiting the STAT5 signaling pathway.

Safety, dose tolerance, pharmacokinetics, and pharmacodynamics of fosciclopirox (CPX-POM) in patients with advanced solid tumors

518

Background: Fosciclopirox (CPX-POM) is being developed for the treatment of non-muscle invasive and muscle invasive bladder cancer. CPX-POM selectively delivers its active metabolite, ciclopirox (CPX), to the entire urinary tract following systemic administration. In a chemical carcinogen mouse model of bladder cancer, CPX-POM treatment resulted in significant decreases in bladder weight, migration to lower stage tumors, inhibition of cell proliferation as well as Notch 1 and Wnt signaling pathways. Methods: Study CPX-POM-001 (NCT03348514) is US multi-site, Phase I, open-label, dose escalation study characterizing the safety, dose tolerance, pharmacokinetics (PK) and pharmacodynamics of IV CPX-POM in advanced solid tumor patients. The PK of CPX-POM, CPX and ciclopirox glucuronide (CPX-G), were characterized in plasma and urine. Circulating biomarkers of Wnt and Notch, IL-6, IL-8 and VEGF were determined. Results: Nineteen patients were enrolled in the study. The starting dose of 30 mg/m2 was administered once daily on Days 1-5 of each 21-day treatment cycle. Doses were escalated to 1200 mg/m2. The MTD was determined to be 900 mg/m2. Overall, the number of treatment-related AE's tended to increase in frequency with dose, nausea and vomiting being the most common. Grade 3 confusion was observed in the 1200 mg/m2 cohort. Four AE's of Grade 1 confusion at 600 and 900 mg/m2. There was no evidence of QTc prolongation or other ECG abnormality. One patient in the 240 mg/m2 dose cohort, with a diagnosis of indolent primary fallopian tube tumor, achieved a partial response per RECIST 1.1. Metabolism of CPX-POM was rapid and complete. The clearance of CPX was dose proportional and time-independent. At MTD, steady-state 24-hour urine CPX concentrations of 215 µM were achieved. Evidence of Notch and Wnt inhibition was observed. Conclusions: IV CPX-POM was well tolerated with treatment-related AEs primarily CNS-related. At MTD, systemic and urinary CPX exposures exceeding in vitro IC50 values by several-fold. The 900 mg/m2 dose is currently being evaluated in an expansion cohort study in cisplatin-ineligible muscle invasive bladder cancer patients scheduled for cystectomy. Clinical trial information: NCT03348514.

Targeting transcription factor TCF4 by γ-Mangostin, a natural xanthone

Given that colon cancer is the third most common cancer in incidence and cause of death in the United States, and current treatment modalities are insufficient, there is a need to develop novel agents. Towards this, here we focus on γ-Mangostin, a bioactive compound present in the Mangosteen (Garcinia mangostana) fruit. γ-Mangostin suppressed proliferation and colony formation, and induced cell cycle arrest and apoptosis of colon cancer cell lines. Further, γ-Mangostin inhibited colonosphere formation. Molecular docking and CETSA (Cellular thermal shift assay) binding assays demonstrated that γ-Mangostin interacts with transcription factor TCF4 (T-Cell Factor 4) at the β-catenin binding domain with the binding energy of -5.5 Kcal/mol. Moreover, γ-Mangostin treatment decreased TCF4 expression and reduced TCF reporter activity. The compound also suppressed the expression of Wnt signaling target proteins cyclin D1 and c-Myc, and stem cell markers such as LGR5, DCLK1 and CD44. To determine the effect of γ-Mangostin on tumor growth in vivo, we administered nude mice harboring HCT116 tumor xenografts with 5 mg/Kg of γ-Mangostin intraperitoneally for 21 days. γ-Mangostin treatment significantly suppressed tumor growth, with notably lowered tumor volume and weight. In addition, western blot analysis revealed a significant decrease in the expression of TCF4 and its downstream targets such as cyclin D1 and c-Myc. Together, these data suggest that γ-Mangostin inhibits colon cancer growth through targeting TCF4. γ-Mangostin may be a potential therapeutic agent for colon cancer.

Preclinical Pharmacokinetics of Fosciclopirox, a Novel Treatment of Urothelial Cancers, in Rats and Dogs

Pharmacokinetic studies in rats and dogs were performed to characterize the in vivo performance of a novel prodrug, fosciclopirox. Ciclopirox olamine (CPX-O) is a marketed topical antifungal agent with demonstrated in vitro and in vivo preclinical anticancer activity in several solid tumor and hematologic malignancies. The oral route of administration for CPX-O is not feasible due to low bioavailability and dose-limiting gastrointestinal toxicities. To enable parenteral administration, the phosphoryl-oxymethyl ester of ciclopirox (CPX), fosciclopirox (CPX-POM), was synthesized and formulated as an injectable drug product. In rats and dogs, intravenous CPX-POM is rapidly and completely metabolized to its active metabolite, CPX. The bioavailability of the active metabolite is complete following CPX-POM administration. CPX and its inactive metabolite, ciclopirox glucuronide (CPX-G), are excreted in urine, resulting in delivery of drug to the entire urinary tract. The absolute bioavailability of CPX following subcutaneous administration of CPX-POM is excellent in rats and dogs, demonstrating the feasibility of this route of administration. These studies confirmed the oral bioavailability of CPX-O is quite low in rats and dogs compared with intravenous CPX-POM. Given its broad-spectrum anticancer activity in several solid tumor and hematologic cancers and renal elimination, CPX-POM is being developed for the treatment of urothelial cancer. The safety, dose tolerance, pharmacokinetics, and pharmacodynamics of intravenous CPX-POM are currently being characterized in a United States multicenter first-in-human Phase 1 clinical trial in patients with advanced solid tumors (NCT03348514).

Pharmacokinetics of ciclopirox prodrug, a novel agent for the treatment of bladder cancer, in animals and humans

e14705

Background: Ciclopirox Prodrug (CPX-POM) is a novel anticancer agent currently being evaluated in patients with advanced solid tumors participating in a First-in-Human, Phase 1 safety, dose tolerance, pharmacokinetics (PK) and pharmacodynamics trial at four US sites. In vitro and in vivo preclinical proof of principle was established in high grade human urothelial cancer cell lines as well as a mouse model of bladder cancer.Methods: A series of in vivo PK studies were conducted in mice, rats and dogs to characterize the absolute bioavailability of CPX following intravenous (IV), subcutaneous (SC) and oral administration of CPX-POM. The single dose and steady-state plasma and urine pharmacokinetics of CPX-POM are also currently being characterized in patients participating in the ongoing Phase 1 trial. Plasma and urine concentrations of the prodrug and metabolites were determined by LC-MS/MS validated in each specie and matrix. Non-parametric pharmacokinetic parameters were generated from resultant plasma and urine drug and metabolite concentration-time data. Results: CPX-POM is rapidly and completely metabolized to CPX in blood via circulating phosphatases in animals and humans. CPX is completely bioavailable following IV CPX-POM administration in mice, rats and dogs. CPX and its major inactive glucuronide metabolite (CPX-G) are extensively eliminated in urine in all animal species. SC administration of CPX-POM demonstrated excellent bioavailability in rats and dogs. Following IV administration of 30-900 mg/m2CPX-POM to patients, the apparent elimination half-life of CPX ranged from 2 to 8 hours, CPX systemic exposure was dose-proportional and time-independent in cancer patients, and a major portion of the dose was eliminated as CPX-G. Conclusions: IV CPX-POM achieves plasma and urine CPX exposures that exceed in vitro IC50 values several-fold at well tolerated doses in animals and humans. CPX pharmacokinetics observed in animals were predictive of human systemic clearance based on allometric scaling. Clinical trial information: NCT03348514.

Pleotropic role of RNA binding protein CELF2 in autophagy induction

We previously reported that ionizing radiation (IR) mediates cell death through the induction of CUGBP elav-like family member 2 (CELF2), a tumor suppressor. CELF2 is an RNA binding protein that modulates mRNA stability and translation. Since IR induces autophagy, we hypothesized that CELF2 regulates autophagy-mediated colorectal cancer (CRC) cell death. For clinical relevance, we determined CELF2 levels in The Cancer Genome Atlas (TCGA). Role of CELF2 in radiation response was carried out in CRC cell lines by immunoblotting, immunofluorescence, autophagic vacuole analyses, RNA stability assay, quantitative polymerase chain reaction and electron microscopy. In vivo studies were performed in a xenograft tumor model. TCGA analyses demonstrated that compared to normal tissue, CELF2 is expressed at significantly lower levels in CRC, and is associated with better overall 5-year survival in patients receiving radiation. Mechanistically, CELF2 increased levels of critical components of the autophagy cascade including Beclin-1, ATG5, and ATG12 by modulating mRNA stability. CELF2 also increased autophagic flux in CRC. IR significantly induced autophagy in CRC which correlates with increased levels of CELF2 and autophagy associated proteins. Silencing CELF2 with siRNA, mitigated IR induced autophagy. Moreover, knockdown of CELF2 in vivo conferred tumor resistance to IR. These studies elucidate an unrecognized role for CELF2 in inducing autophagy and potentiating the effects of radiotherapy in CRC.

Co-localization of autophagy-related protein p62 with cancer stem cell marker dclk1 may hamper dclk1's elimination during colon cancer development and progression

Autophagy may play a critical role in colon cancer stem cells (CCSCs)-related cancer development. Here, we investigate whether accumulation of infection/injury-induced CCSCs due to impaired autophagy influences colon cancer development and progression. When Apc⁺⁺ mice were infected with Citrobacter rodentium (CR; 10⁹CFUs), we discovered presence of autophagosomes with increases in Beclin-1, LC3B and p62 staining during crypt hyperplasia. Apc1638N/+ mice when infected with CR or subjected to CR+AOM treatment, exhibited increased colon tumorigenesis with elevated levels of Ki-67, β-catenin, EZH2 and CCSC marker Dclk1, respectively. AOM/DSS treatment of Apc1638N/+ mice phenocopied CR+AOM treatment as colonic tumors exhibited pronounced changes in Ki-67, EZH2 and Dclk1 accompanied by infiltration of F4/80+ macrophages, CD3+ lymphocytes and CD3/β-catenin co-localization. Intestinal and colonic tumors also stained positive for migrating CSC markers CD110 and CDCP1 wherein, colonic tumors additionally exhibited stromal positivity. In tumors from CR-infected, CR+AOM or AOM/DSS-treated Apc1638N/+ mice and surgically-resected colon tumor/metastatic liver samples, significant accumulation of p62 and it's co-localization with LC3B and Dclk1 was evident. Apc^Min/+ mice when infected with CR and BLT1^−/−;Apc^Min/+ mice, exhibited similar co-localization of p62 with LC3B and Dclk1 within the tumors. Studies in HCT116 and SW480 cells further confirmed p62/Dclk1 co-localization and Chloroquin/LPS-induced increases in Dclk1 promoter activity. Thus, co-localization of p62 with Dclk1 may hamper Dclk1's elimination to impact colon cancer development and progression.

Metastatic Tumor-in-a-Dish, a Novel Multicellular Organoid to Study Lung Colonization and Predict Therapeutic Response

Metastasis is a major cause of cancer-related deaths. A dearth of preclinical models that recapitulate the metastatic microenvironment has impeded the development of therapeutic agents that are effective against metastatic disease. Because the majority of solid tumors metastasize to the lung, we developed a multicellular lung organoid that mimics the lung microenvironment with air sac-like structures and production of lung surfactant protein. We used these cultures, called primitive lung-in-a-dish (PLiD), to recreate metastatic disease using primary and established cancer cells. The metastatic tumor-in-a-dish (mTiD) cultures resemble the architecture of metastatic tumors in the lung, including angiogenesis. Pretreating PLiD with tumor exosomes enhanced cancer cell colonization. We next tested the response of primary and established cancer cells to current chemotherapeutic agents and an anti-VEGF antibody in mTiD against cancer cells in two-dimensional (2D) or 3D cultures. The response of primary patient-derived colon and ovarian tumor cells to therapy in mTiD cultures matched the response of the patient in the clinic, but not in 2D or single-cell-type 3D cultures. The sensitive mTiD cultures also produced significantly lower circulating markers for cancer similar to that seen in patients who responded to therapy. Thus, we have developed a novel method for lung colonization in vitro, a final stage in tumor metastasis. Moreover, the technique has significant utility in precision/personalized medicine, wherein this phenotypic screen can be coupled with current DNA pharmacogenetics to identify the ideal therapeutic agent, thereby increasing the probability of response to treatment while reducing unnecessary side effects. SIGNIFICANCE: A lung organoid that exhibits characteristics of a normal human lung is developed to study the biology of metastatic disease and therapeutic intervention.

Large-Scale Production of Salt Fortified with Iodine and Iron

A new dry-mixing process for producing iodine- and iron-fortified salt on a large scale (20 30 metric tons per shift) was developed in salt factories at Valinokkam and Hyderabad, India. Common salt is mixed with 1% sodium hexametaphosphate, 0.5% ferrous sulphate heptahydrate, and 0.0055% potassium iodide or 0.007% potassium iodate in a ribbon blender. Dry mixing is superior to spray mixing and is associated with no operational problems. The fortified salt produced by this method retains the original colour of the unfortified salt, and the distribution of iodine and iron is uniform. The acceptability of the fortified salt is satisfactory, as various food preparations using the product are indistinguishable in colour, taste, and flavour from those containing unfortified salt

Abstract 2865: Ciclopirox olamine: A common antifungal agent that inhibits growth of esophageal tumor cells in vitro and in vivo

Esophageal carcinoma continues to carry a poor prognosis due presentation at advanced stages. Current chemotherapeutics often only prolong survival for months to a few years. Drug repositioning is an important pharmacologic strategy that involves investigation and implementation of known drugs for treatment of new diseases. This method significantly reduces the costs required for establishing the safety of a drug and is associated with higher rates of drug approval. Ciclopirox olamine (CPX) is an antifungal agent that has been on the market since the 1970s. The mechanism of action is believed to include disruptions of DNA repair and cell division signals. Recently, however, this drug has been studied for its antitumor properties demonstrated in human rhabdomyosarcoma, breast carcinoma, colon adenocarcinoma, bladder carcinoma, and hematologic malignancies. To date, there are no studies related to the effect of CPX on esophageal cancer. Here, we show that ciclopirox olamine causes growth inhibition of four esophageal cell lines: TE-10, SKGT4, FLO1 and ESO1. This growth inhibition is demonstrated by hexosaminidase assay performed after incubation with the drug for 24-72 h. The IC50 values range between 5-20µM depending on the cell line used. Cell death was also demonstrated by immunofluorescent staining with Hoschst and propidium iodide, which shows a decrease in the number of viable cells with increasing concentrations of CPX. Clonogenicity assay was also performed with each cell line and demonstrates a decrease in the ability of cells to form colonies after 24 and 48 hour treatment with CPX and subsequent incubation in standard media for 5-7 days. Cell cycle analysis demonstrates G0/G1 arrest in cells treated with CPX. The effects of CPX on the cell cycle are further supported by Western blot analysis showing a decrease in in CDK4 and CDK6, which are necessary for cell cycle progression from the G0/G1 phase. We have also found that treatment with CPX results in a decrease in β-catenin in TE10 cells, suggesting that the drug is affecting this pathway to cause growth inhibition of tumor cells. Finally, we used our ESO1 mouse esophageal squamous cell carcinoma cell line for a xenograft study in which tumor cells were injected into the flanks of mice. Mice treated with intraperitoneal injections of 300 mg/m2 of CPX had smaller tumor volumes compared to untreated controls. In summary, we have shown that CPX inhibits growth of esophageal tumor cells both in vitro and in vivo. Our data suggest that CPX induces cell cycle arrest of tumor cells. The mechanism of tumor cell inhibition may be related to downregulation of the WNT/β-catenin signaling pathway. In future studies, we plan to analyze the effects of CPX on other components in the WNT family from in vitro cells as well as tumor xenografts.

Citation Format: Randi J. Ryan, Prabhu Ramamoorthy, Dharmalingam Subramaniam, Shrikant Anant, Scott Weir. Ciclopirox olamine: A common antifungal agent that inhibits growth of esophageal tumor cells in vitro and in vivo [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 2865.

Abstract 5882: Bench-to-bedside translation of ciclopirox prodrug for the treatment of non-muscle invasive and muscle-invasive bladder cancer

Ciclopirox (CPX) is contained in a number of FDA-approved topical antifungal drug products as the free acid and olamine salt. CPX possesses anticancer activity in a number of in vitro and in vivo preclinical models. Its clinical utility is limited as an oral anticancer agent, however. The oral bioavailability of CPX is quite low due to extensive first pass effect. The poor water solubility of CPX and its olamine salt prevent formulation as an injectable drug product. Thirdly, dose-limiting gastrointestinal toxicities were observed following four times daily oral dosing of CPX in patients with advanced hematologic malignancies. Ciclopirox Prodrug (CPX-POM), in contrast, has demonstrated excellent bioavailability via injectable routes of administration. Here we describe the preclinical characterization of CPX-POM, a novel anticancer agent being developed for the treatment of non-muscle invasive (NMIBC) and muscle invasive (MIBC) bladder cancer. Following IV, SQ and IP administration to mice, CPX-POM is rapidly and completely metabolized to CPX in blood via circulating phosphatases. CPX and its major, inactive glucuronide metabolite are extensively eliminated in urine. At well-tolerated doses, steady-state urine concentrations of CPX exceed in vitro IC50 values in mice by 15-30 fold. CPX inhibited cell proliferation, colony formation, and bladdosphere formation in vitro in T24 (NMIBC) and 253JBV (MIBC) human cell lines in both concentration- and time-dependent manners with IC50 values of 2-4 µM. CPX exposure increased the percentage of NMIBC and MIBC cells arrested at the S and G0/G1 phases, and induced cell death. CPX exposure significantly reduced expression of genes at the mRNA level involved in cancer stem cell signaling pathways including Notch, Wnt, and Hedgehog. CPX was shown to inhibit bladder cancer cell growth in vitro by inhibiting the Notch 1 signaling pathway. The validated N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) chemical carcinogen mouse model of bladder cancer was employed to establish in vivo preclinical proof of principle for CPX-POM. Over the once-daily IP dose range of 25-200 mg/kg, CPX-POM treatment resulted in significant decreases in bladder weight, a clear migration to lower stage tumors, dose-dependent reduction in Ki67 and PCNA staining, as well as a reduction in PCNA-expressing cells. All CPX-POM doses were well tolerated with no evidence of toxicity to the urinary tract based on blinded pathologic evaluation. There were also dose-dependent decreases in Notch 1, Presenilin 1, and Hey 1 in bladder cancer tissues obtained from CPX-POM treated animals. Tumor response was similar, in vivo, following once-daily and three-times weekly CPX-POM administration. CPX-POM has received FDA clearance to proceed to Phase I, and is currently being evaluated in a first-in-human trial in patients with advanced solid tumors.

Citation Format: Scott J. Weir, Partha Ranjarajan, Robyn Wood, Karl Schorno, Prabhu Ramamoorthy, Lian Rajweski, Kathy Heppert, Michael J. McKenna, William McCulloch, Greg A. Reed, Amanda Brinker, Michael J. Baltezor, Roy A. Jensen, John A. Taylor, Shrikant Anant. Bench-to-bedside translation of ciclopirox prodrug for the treatment of non-muscle invasive and muscle-invasive bladder 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 5882.

Abstract 5032: Tumor in a Dish (TiD): Novel approach for precision therapy using patient-derived cells

Metastatic colorectal cancer is a major cause of cancer-related deaths. Most patients with metastatic disease fail to respond to current chemotherapeutic agents. Current, traditional culture model is not appropriate to study the metastatic disease in in vitro condition. Hence, there is an ominous need for developing new therapeutic and preventive agents that can target metastatic cancer. Unfortunately, there are no good in vitro as well as in vivo models available for studying metastatic disease. Hence, in this abstract, we demonstrate the development of a new lung model system, called Primitive Lung in a Dish or PLiD with cancer cells called “Tumor in a Dish” or TiD. The PLiD system shows expression of specific cell type marker like E-cadherin (epithelial cell) vimentin (fibroblast), CD31 (heme-endothelial cells) and LYVE1 (lymph-endothelial cells). Interestingly, we showed expression of lung functional protein like surfactant protein B and D. In the multicell type TiD system, cancer cells were grown in a 3-dimensional (3D) PLiD system containing normal epithelial cells, fibroblasts and endothelial cells. The model resembles in vivo tumor microenvironments, including cell-cell contact, tumor architecture, and the influence of different cell types. We next determined the efficacy of standard colon cancer chemotherapeutic agents. We observed differential activity of 5FU in TiD system when compared to standard 2D and single-cell type 3D cultures. Another surprising result we found was with freshly isolated colon cancer cells from patient samples. Without knowing the genetic characteristics of the cancer tissue, the TiD system was able to identify cells that were resistant to oxaliplatin. Moreover, using this method, we have developed novel drugs that target cancer cells while not affecting the normal tissue. More importantly, the technique has significant utility in precision/personalized medicine, wherein this phenotypic screen can be coupled with current DNA pharmacogenetics to identify the ideal therapeutic agent, thereby increasing the probability of response to treatment while reducing unnecessary side effects.

Citation Format: Prabhu Ramamoorthy, Sufi Thomas, Sathish Ramalingam, Gaurav Fnu, Sita G. Sittampalam, Roy A. Jensen, Shrikant Anant. Tumor in a Dish (TiD): Novel approach for precision therapy using patient-derived cells [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 5032.

Expression of Hypoxia Inducible Factor 1alpha Is Protein Kinase A-dependent in Primary Cortical Astrocytes Exposed to Severe Hypoxia

The hypoxia inducible factor 1 (HIF-1) and the cyclic AMP-responsive element binding protein (CREB) are two transcription factors that have been studied in the context of neuronal survival and neurodegeneration. HIF-1 upregulation and CREB activation have been observed not only in neurons but also in astrocytes under conditions of hypoxia. We hypothesized that activation of CREB regulate HIF-1α expression in the nucleus of cortical astrocytes under in vitro ischemic condition. To test the hypothesis, we determined the effects of inhibiting the CREB activation pathway on the expression of HIF-1α protein in astrocytes exposed to CoCl₂ and severe hypoxia (near anoxia, 0.1% O₂). The results demonstrated that inhibition of CaMKII and CaMKIV had no effect on both HIF-1α and pCREB expression in cortical astrocytes exposed to CoCl₂ and anoxia. In contrast, PKA inhibition lowered the expression of HIF-1α and pCREB expression. Furthermore, the inhibition of PKA but not CaMKII or CaMKIV increased cell death of astrocytes exposed to near anoxia. The results suggest that PKA plays an important role in the cell survival signaling pathways in astrocytes.

Abstract B36: Targeting BRCA1 through natural HSP90 inhibitors to reverse platinum resistance in TNBC

Background: Triple-negative breast cancers (TNBCs) are highly associated with an aggressive clinical course, resistance to chemotherapy, and poor prognosis compared to other breast cancer subtypes. However, breast cancers arising in BRCA1 mutation carriers appear to be particularly sensitive to platinum-based chemotherapy agents. The tumor suppressor BRCA1 (breast cancer type 1 susceptibility protein) is part of a protein complex that repairs DNA damage by homologous recombination. Recent studies have shown that tumor cells expressing high levels of BRCA1 are resistant to both ionizing radiation (IR) and platinum-based chemotherapy agents, and that ablation of BRCA1 expression can restore sensitivity to these agents. We have demonstrated that the chaperone protein heat shock protein 90 (HSP90) is required for BRCA1 stability. However, established HSP90 inhibitors exhibit a high level of toxicity unrelated to HSP90. Recently, we observed that the natural compounds gedunin and celastrol modulate HSP90 activity without inducing side effects. We believe that combinatory use of these compounds can further reduce BRCA1 expression beyond their individual effect to overcome BRCA1-mediated resistance to platinum-based chemotherapies.

Study Design: The goal of these experiments is to demonstrate that combination treatment with the HSP90 inhibitors gedunin and celastrol will maximize BRCA1 degradation (via inhibition of HSP90), impair the DNA repair system, and allow carboplatin to effectively eradicate TNBC cells. We will confirm that this is a HSP90 mediated event that results in the impairment of DNA repair. Using in vivo models of breast cancer, we will demonstrate that natural compounds could sensitize BRCA1-expressing TNBC cells to carboplatin, inhibiting breast cancer progression and tumor growth.

Results: Using Western blot analysis, we observed that the combination of gedunin and celastrol attenuates HSP90 activity, leading to a dose-dependent reduction in BRCA1 degradation in HCC1937BRCA1 TNBC cells. Additionally, we the combination facilitated carboplatin-mediated inhibition of proliferation in both BT-20 and HCC1937BRCA1 cells. Immunofluorescence staining for g-H2AX and RAD51 demonstrated that the two HSP90 inhibitors prevent BRCA1-mediated recruitment of DNA repair complexes following ionizing radiation-induced DNA damage. To test the effects of celastrol and gedunin in vivo, we generated mouse xenografts by performing fat pad injections of HCC1937BRCA1 cells. Mice were dosed I.P. every 5 days with celastrol (5 mg/kg), gedunin (5 mg/kg), and carboplatin (25 mg/kg) for 20 days. Treatment with the HSP90 inhibitors along with carboplatin resulted in significant reduction in both tumor size and weight. In contrast treatment with carboplatin alone resulted in tumors of size similar to vehicle-treated animals. Additionally, phospho-H3 and cleaved caspase 3 immunofluorescence staining indicated a corresponding decrease in cell proliferation and increased apoptosis in tumors from celastrol+gedunin+carboplatin -treated animals compared to either vehicle or carboplatin alone-treated. Future studies will focus on examining the effects of this combination treatment in TNBC xenografts created with patient specimens, and in defining the interaction between HSP90 and BRCA1.

Significance: In order to increase survival rates in TNBC patients, it is essential that resistance to chemotherapy be overcome. Successful completion of these studies demonstrating that natural compounds can act as HSP90 inhibitors to reverse platinum resistance without added toxicity would facilitate their rapid incorporation into clinical trials and provide a critically needed therapy for women with TNBC.

Citation Format: Kelli Valdez, Prabhu Ramamoorthy, Shrikant Anant, Roy Jensen. Targeting BRCA1 through natural HSP90 inhibitors to reverse platinum resistance in TNBC [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr B36.

Abstract 3314: Targeting Hsp90 affects stem cell signaling in triple negative breast cancer

Background: Triple Negative Breast Cancer (TNBC) exhibit dismal survival rates due to their propensity to develop distant metastases. Heat shock protein 90 (Hsp90) is a molecular chaperone that aids in the folding and maturation of various proteins involved in breast cancer progression and resistance to therapy. Many studies have also suggested that breast cancer's ability to proliferate, progress, and spread is due to the presence of a rare subpopulation of cancer stem cells. The aim of this study is to investigate the efficacy of HSP90 inhibitors celastrol and triptolide (from the Chinese herb “Thunder God of Vine” (Tripterygium wilfordii) on stem cells as a novel therapy for TNBC.

Methods: We performed in vitro studies using the TNBC cell lines BT20 and MDA-MB-231. We performed mammosphere assays to determine self-renewal capacity. For in vivo, we injected BT20 cells into flanks of athymic nude mice and treated with celastrol and triptolide at 3 mg/Kg bw and 0.25 mg/Kg bw, respectively.

Results: Both celastrol and triptolide significantly suppressed mammosphere size and number. Furthermore, expression of breast cancer stem cell markers DCLK1, ALDH1 and CD133 were significantly reduced in the two cell lines following treatment. Flow cytometry also suggested a significant reduction in DCLK1+, ALDH+ and CD133+ cells. Recently, Notch signaling has been shown to be critical for self-renewal of cancer stem cells. In cells treated with either celastrol or triptolide, there was a significant reduction in activated Notch intracellullar domain (NICD), and its downstream target Hes-1. However, in cells where we ectopically overexpressed NICD, neither compound was as potent as control, vector transfected cells in reducing 2D cell proliferation or 3D mammosphere formation, suggesting the direct role for inhibiting Notch activation as a mechanism of action for the two compounds. Furthermore, inhibition of Notch signaling pathway by using Υ-secretase inhibitor DAPT shows further reduction in mammosphere formation and Notch and its downstream target gene. We confirmed these finding in vivo using BT20 tumor xenografts grown in athymic nude mice. There was a reduction in the size and weight of tumors in mice treated with celastrol or triptolide. Western blot data showed that there is a decrease in activated Notch-1 protein and stem cell marker, DCLK1+ and ALDH+ in celastrol and triptolide treated xenograft tissue.

Conclusion: Taken together these data suggest that both celastrol and triptolide affect cancer stem cells in TNBC, in part through inhibition of Notch signaling.

Citation Format: Prabhu Ramamoorthy, Parthasarathy Rangarajan, Roy Jensen, Shrikant Anant. Targeting Hsp90 affects stem cell signaling in triple negative breast 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 3314.

Abstract 3832: Combination use of natural Hsp90 inhibitors to reverse BRCA1-mediated platinum resistance in triple negative breast cancer

Background: Triple-negative breast cancers (TNBCs) are highly associated with an aggressive clinical course and poor prognosis, largely due to resistance to chemotherapy. Platinum-based therapies act by causing DNA damage, which in the absence of a functional DNA repair system, leads to cancer cell death. BRCA1, a well-studied tumor suppressor, is critical for repairing DNA damage by homologous recombination. This ability makes BRCA1 an attractive therapeutic target for the re-sensitization of cancer cells to platinum chemotherapies. Recently, we have demonstrated that the chaperone protein heat shock protein 90 (HSP90) is required for BRCA1 stability. While targeted elimination of HSP90s results in a loss of BRCA1, current pharmacological inhibitors also exhibit toxicity unrelated to HSP90. We have found that the natural compounds gedunin, triptolide, and celastrol can modulate HSP90 expression without negative side effects. We believe that combinatory use of these non-toxic compounds can further reduce BRCA1 expression beyond their individual effect to overcome BRCA1-mediated resistance to platinum-based chemotherapies.

Study Design: The goal of these experiments is to identify a combination of gedunin, celastrol, and triptolide to maximize BRCA1 degradation (via inhibition of HSP90), impairing the DNA repair system, and allowing carboplatin to effectively eradicate TNBC cells. Using in vitro techniques we will identify the most potent combination of gedunin, celastrol and triptolide to maximize BRCA1 degradation. We will then confirm that this is a HSP90 mediate event that results in the impairment of DNA repair. Using in vivo models of breast cancer we will demonstrate that natural compounds will sensitize BRCA-expressing TNBC cells to carboplatin, inhibiting breast cancer progression and tumor growth.

Results: Using Western analysis, we have found that gedunin, celastrol and triptolide each can attenuate HSP90 activity, leading to BRCA1 degradation in BT-20 and MDA-MB-231 TNBC cells. Additionally, we have observed that gedunin, celastrol, and triptolide can each prevent formation of radiation-induced DNA repair complex, as evident by γ-H2AX staining, in HCC1937BRCA1 TNBC cells. Once we identify the most potent combination of our natural compounds, TNBC xenografts with be created and treated with the combination and carboplatin to demonstrate sensitivity to platinum treatment and inhibition of breast cancer progression.

Significance: In order to increase survival rates in TNBC patients, it is essential that resistance to chemotherapy be overcome. Successful completion of these studies demonstrating that natural compounds can act as HSP90 inhibitors to reverse platinum resistance without added toxicity would facilitate their rapid incorporation into clinical trials and provide a critically needed therapy for women with TNBC.

Citation Format: Kelli E. Valdez, Prabhu Ramamoorthy, Shrikant Anant, Roy Jensen. Combination use of natural Hsp90 inhibitors to reverse BRCA1-mediated platinum resistance in triple negative breast 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 3832.

Abstract 1310: Targetingprolactin signaling to suppress pancreatic cancer stem cells

Background: Pancreatic cancer (PCa) is a major cause of cancer related mortality in United States with &lt; 6% survival rate. It is an aggressive and devastating disease, which is characterized by poor prognosis, invasiveness, rapid progression, profound resistance to drug treatment and recurrance after surgery. Presently, single agent based chemotherapy (e.g. Gemcitabine) is the major treatment for metastatic adenocarcinoma of pancreas but it has a tumor response rate of below 10%. Moreover combination therapy of gemcitabine and erlotinib only marginally improved survival rate. Hence, there is a dire need to identify novel ways to inhibit pancreatic cancer growth.

Methods: PCa cells (MiaPaCa-2 and PanC-1) were grown to 70-80% of confluency and treated with and without prolactin (PRL) and JAK2, STAT3 and ERK phosphorylation in presence and absence of antipsychotic compound were evaluated by western blot. Growth of PCa lines (MiaPaCa-2, PanC-1, BxPC-3, AsPC-1) and normal ductal epithelial cells (HPNE) was measured by hexosaminidase and clonogenicity, respectively. Pancosphere formation was used to identify effects on stem cells.

Results: We have recently identified that the receptor for the pituitary hormone prolactin is overexpressed in pancreatic cancers, and in pancreatic cancer cell lines. When prolactin (PRL) binds its cognate receptor (PRLR), it induces various downstream events including the JAK-STAT and ERK MAPK pathways. In pancreatic cancer cell lines, we observe that PRL treatment induced dose- and time-dependent JAK2, STAT3, and ERK1/2 phosphorylation. Furthermore, there was an increase in the expression of cancer stem cell (CSC) markers DCLK1 (doublecortin calmodulin like kinase 1) and CD44. In addition, PRL-induced pancosphere formation further suggesting that PRL affects stem cells. Based on these data, we conclude that PRL signaling enhances stemness in pancreatic cancers, and therefore we decided to target it for therapeutic intervention. For this, we developed a homology model for the C-terminal intracellular region of the receptor and performed a virtual screening in silico with FDA approved drugs. One compound, a first generation antipsychotic drug diphenylbutylpiperidine, also called Penfluridol was found to interact with the region of the receptor that also binds site for JAK2. The compound has a long half-life, and is used in the treatment of chronic schizophrenia and similar psychotic disorders. We have further determined that Penfluridol inhibits PRL-induced STAT3 and ERK phosphorylation. In addition, the compound reduced proliferation, colony formation, and spheroid formation. Moreover, it induced cells to undergo autophagy by activating LC3B and increasing expression of autophagy-related genes ATG5, 7 and 12.

Conclusions: PRL signaling through its cognate PRLR receptor is critical for aggressive pancreatic cancer behavior, and therefore may be an effective therapeutic strategy.

Citation Format: Prasad Dandawate, Gaurav Kaushik, Dharmalingam Subramaniam, Prabhu Ramamoorthy, Scott J. Weir, Roy A. Jensen, Shrikant Anant. Targetingprolactin signaling to suppress pancreatic cancer stem cells. [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 1310.

Abstract 4632: Effects of Hsp90 inhibitors on triple-negative breast cancer: BRCA1 as a therapeutic target for TNBC

Background: Breast cancer is the second leading cause of death for woman. Within breast cancer, those classified as Triple Negative Breast Cancer (TNBC) exhibit dismal survival rates due to their propensity to develop distant metastases. Heat shock protein 90 (Hsp90) is a molecular chaperone that aids in the folding and maturation of various proteins involved in breast cancer progression and resistance to therapy. The aim of this study was to elucidate whether the two natural inhibitors of Hsp90, celastrol and triptolide inhibit triple negative breast cancer growth. Both these compounds are terpenoids and were obtained from the Chinese herb “Thunder God of Vine” (Tripterygium wilfordii).

Methods: BT20, BT549, MDA-MB-157 and MDA-MB-231 cells (all TNBC cells), and immortalized human mammary epithelial cells (HMLE) were grown in DMEM containing 10% FBS as per ATCC recommendations. Cell proliferation was assessed by hexoseaminidase activity, and IC50 values calculated using GraphPad Prism5. For clonogenicity, 500 cells were incubated with IC50 concentrations of each compound for 24 h, after which they were allowed to grow and form colonies. For in vivo, BT20 cells were injected into flanks of athymic nude mice and treated with celastrol and triptolide at 3 mg/Kg bw and 0.25 mg/Kg bw, respectively.

Results: Celastrol and triptolide treatment suppressed proliferation and colony forming ability of all four TNBC cell lines, but not that of the immortalized HMLE cells. The compounds increased apoptotic cell death, based on increased Annexin V staining. Moreover, there was increased expression of the pro-apoptotic protein Bax but decreased expression of the anti-apoptotic protein, Bcl2 and BclXL. Immunoprecipitation-coupled western blots also showed that the compounds inhibit HSP90/CDC37 complex formation. Interestingly, the coupled immunoprecipitation-western blot analyses showed increased HSP90-BRCA1 interaction after treatment with the compounds. Coupled to this, western blot and immunostaining assays showed increased cytosolic levels and reduced nuclear levels of BRCA1 protein. Similar results were obtained in vivo with BT20 xenografts. In addition to decreased tumor size in response to treatment with celastrol or triptolide, the xenograft tissues showed an increase in cytoplasmic BRCA1 levels following treatment. In addition, there was increased in HSP90-BRCA1 complex formation in the treated xenograft tissues. Finally, knockdown of BRCA1 using specific silencer RNA resulted in partial inhibition in cell growth reduction after celastrol and triptolide treatment in both BT20 and MDA-MB-231 cells.

Conclusion: Taken together, these data suggest that both celastrol and triptolide suppress TNBC cell growth, in part through increasing cytosolic HSP90/BRCA1 complex formation.

Citation Format: Prabhu Ramamoorthy, Parthasarathy Rangarajan, Ossama Tawfik, Shrikant Anant, Roy A. Jensen. Effects of Hsp90 inhibitors on triple-negative breast cancer: BRCA1 as a therapeutic target for TNBC. [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 4632.

Abstract 1727: Quinomycin A inhibits pancreatic cancer growth and affects stem cell viability by inhibiting oncogenic YAP1 function

Background: Pancreatic cancer (PCa) remains a leading cause of death in the United States. Cancer stem cells (CSC) are responsible for tumor behavior, and therapeutic resistance. Quinomycin (Qui) is an orally administered quinoxaline antibiotic that bifunctionally intercalates with double stranded DNA. As a first step for repurposing this drug, we determined whether Qui affects PCa growth, and if so whether this is by suppressing stem cells.

Method: Growth and apoptosis of PCa lines (MiaPaCa-2, PanC-1, BxPC-3) and normal ductal epithelial cells (HPNE) was measured by hexosaminidase and clonogenicity, and caspase 3/7 assays, respectively. Pancosphere formation and FACS sorting were used to identify effects on stem cells. For in vivo, MiaPaCa-2 xenografts were developed in the flanks of nude mice. Immunohistochemistry was performed for stem cell markers and Hippo signaling proteins.

Results: Qui demonstrated a dose- and time-dependent inhibition of proliferation and colony formation in all three PCa lines but not HPNE cells. Qui induced PCa cells to undergo apoptosis. It also significantly reduced the number and size of pancospheres, and flow cytometry and western blot analyses confirmed that Qui suppressed PCa stem cell marker proteins DCLK1, CD44, CD24 and EPCAM. We next determined whether Hippo signaling pathway is affected. For this, we tested the effect of Qui on Hippo signaling pathway, which is an active pathway in CSCs including in PCa. The key effector protein, YAP1 has been shown to be oncogenic in many cancer types. In the canonical Hippo signaling pathway, YAP1 function is inhibited. When YAP1 is phosphorylated at Ser127 by the action of upstream Mst1/2 and Lats1/2 kinases, it is sequestered in the cytoplasm, and therefore no induction of downstream gene expression. Qui significantly decreased the phosphorylation oncogenic YAP1. Furthermore, Qui inhibited the expression of YAP interacting proteins TEAD1, TEAD2, and TEAD4. On the other hand, ectopic expression of the TEAD1 partially rescued the cells from Qui-mediated growth suppression. To determine the effect of Qui on tumor growth in vivo, mice carrying MiaPaCa-2 tumor xenografts were administered the compound intraperitoneally (20 μg/kg bw) every day for 21 days. Qui treatment significantly suppressed tumor xenograft growth, with notably lower tumor volume and weight. Western blot and immunohistochemistry analyses demonstrated significant inhibition in the expression of CSC marker proteins, oncogenic YAP1 phosphorylation and YAP1 interacting proteins TEAD1 in the Qui-treated xenograft tissues.

Conclusion: Together, these data suggest that Qui suppresses PCa growth that targets that targets stem cells by inhibiting oncogenic YAP1 in Hippo signaling pathway.

Citation Format: Dharmalingam Subramaniam, Sivapriya Ponnurangam, Gaurav Fnu, Prabhu Ramamoorthy, Animesh Dhar, Ossama W. Tawfik, Shahid Umar, Scott J. Weir, Roy A. Jensen, Arun Balakrishnan, Shrikant Anant. Quinomycin A inhibits pancreatic cancer growth and affects stem cell viability by inhibiting oncogenic YAP1 function. [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 1727.

Abstract 1893: Honokiol prevents colonic tumorigenesis and affects stem cell viability by affecting oncogenic YAP1 function

Background: Despite advances in early detection, colon cancer remains the second leading cause of death in the United States. We are focused on developing dietary prevention strategies. HNK (HNK) is a biphenolic compound that is used in the traditional Chinese Medicine for treating various ailments. The current study is designed to determine whether HNK affected colon cancer stem cells and to identify a mechanism.

Method: Colon cancer (CRC) cell lines HCT116 and SW480 and normal colon epithelial cells were used in the study. Cell growth was measured by hexoseaminidase and clonogenicity assays. Apoptosis was determined by measuring caspase 3/7 activities. Colosphere formation assay and FACS sorting were used for stem cells. For in vivo effects, we used the AOM/DSS-induced colonic tumorigenesis model. Immunohistochemistry was determined for stem cell markers and Hippo signaling proteins.

Results: HNK induced a significant dose-dependent inhibition of proliferation and colony formation of the two CRC lines, but induced apoptosis. HNK did not affect the normal cells. To demonstrate HNK effects on stem cells, we performed colosphere assays. HNK significantly reduced the number and size of colospheres, suggesting effects on stem cells. In addition, colon stem cell marker proteins DCLK1, LGR5, and CD44 were also decreased. Further proof was obtained by flow cytometry analyses, where HNK reduced the number of DCLK1+ cells. We next determined whether stem cell signaling is affected. For this, we looked at the Hippo signaling pathway, which is active in intestinal stem cells. The key effector protein of this pathway, YAP1 is also oncogenic in many cancer types. In the canonical Hippo signaling pathway, YAP1 function is inhibited. When YAP1 is phosphorylated at Ser127 by the action of upstream Mst1/2 and Lats1/2 kinases, it is sequestered in the cytoplasm where it is degraded, thereby inhibiting downstream gene expression. HNK significantly reduced YAP1 levels. Furthermore, HNK inhibited the expression of YAP interacting proteins TEAD1, TEAD2, and TEAD4. On the other hand, ectopic expression of the TEAD1 partially rescued the cells from HNK-mediated growth suppression. To determine the in vivo effect of HNK on AOM/DSS induced colonic tumorigenesis, HNK were oral gavaged at a dose of 5mg/kg bw for 24 weeks. HNK treatment significantly reduced the colonic tumor numbers and size. Western blot and immunohistochemistry analyses demonstrated significant inhibition in the expression of stem marker proteins, oncogenic YAP1 phosphorylation and TEAD1 in the HNK-treated AOM/DSS colonic tumor tissues.

Conclusion: Together, these data suggest that HNK prevents colonic tumorigenesis that targets stem cells by inhibiting oncogenic YAP1 in Hippo signaling pathway.

Citation Format: Dharmalingam Subramaniam, Sivapriya Ponnurangam, Deep Kwatra, Gaurav Kaushik, Prabhu Ramamoorthy, Satish Ramalingam, Ossama Tawfik, Scott J. Weir, Subhash Padhye, Dan A. Dixon, Shahid Umar, Roy A. Jensen, Shrikant Anant. Honokiol prevents colonic tumorigenesis and affects stem cell viability by affecting oncogenic YAP1 function. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1893. doi:10.1158/1538-7445.AM2015-1893

Honokiol inhibits melanoma stem cells by targeting notch signaling

Melanoma is an aggressive disease with limited therapeutic options. Here, we determined the effects of honokiol (HNK), a biphenolic natural compound on melanoma cells and stemness. HNK significantly inhibited melanoma cell proliferation, viability, clonogenicity and induced autophagy. In addition, HNK significantly inhibited melanosphere formation in a dose dependent manner. Western blot analyses also demonstrated reduction in stem cell markers CD271, CD166, Jarid1b, and ABCB5. We next examined the effect of HNK on Notch signaling, a pathway involved in stem cell self-renewal. Four different Notch receptors exist in cells, which when cleaved by a series of enzymatic reactions catalyzed by Tumor Necrosis Factor-α-Converting Enzyme (TACE) and γ-secretase protein complex, results in the release of the Notch intracellular domain (NICD), which then translocates to the nucleus and induces target gene expression. Western blot analyses demonstrated that in HNK treated cells there is a significant reduction in the expression of cleaved Notch-2. In addition, there was a reduction in the expression of downstream target proteins, Hes-1 and cyclin D1. Moreover, HNK treatment suppressed the expression of TACE and γ-secretase complex proteins in melanoma cells. To confirm that suppression of Notch-2 activation is critical for HNK activity, we overexpressed NICD1, NICD2, and performed HNK treatment. NICD2, but not NICD1, partially restored the expression of Hes-1 and cyclin D1, and increased melanosphere formation. Taken together, these data suggest that HNK is a potent inhibitor of melanoma cells, in part, through the targeting of melanoma stem cells by suppressing Notch-2 signaling.

Ischemia induces different levels of hypoxia inducible factor-1α protein expression in interneurons and pyramidal neurons

Introduction

Pyramidal (glutamatergic) neurons and interneurons are morphologically and functionally well defined in the central nervous system. Although it is known that glutamatergic neurons undergo immediate cell death whereas interneurons are insensitive or survive longer during cerebral ischemia, the protection mechanisms responsible for this interneuronal survival are not well understood. Hypoxia inducible factor-1 (HIF-1) plays an important role in protecting neurons from hypoxic/ischemic insults. Here, we studied the expression of HIF-1α, the regulatable subunit of HIF-1, in the different neuronal phenotypes under in vitro and in vivo ischemia.

Results

In a primary cortical culture, HIF-1α expression was observed in neuronal somata after hypoxia (1% oxygen) in the presence of 5 or 25 mM glucose but not under normoxia (21% oxygen). Interestingly, only certain MAP2-positive neurons containing round somata (interneuron-like morphology) co-localized with HIF-1α staining. Other neurons such as pyramidal-like neurons showed no expression of HIF-1α under either normoxia or hypoxia. The HIF-1α positive neurons were GAD65/67 positive, confirming that they were interneuron-type cells. The HIF-1α expressing GAD65/67-positive neurons also possessed high levels of glutathione. We further demonstrated that ischemia induced significant HIF-1α expression in interneurons but not in pyramidal neurons in a rat model of middle cerebral artery occlusion.

Conclusion

These results suggest that HIF-1α protein expression induced by ischemia is neuron-type specific and that this specificity may be related to the intracellular level of glutathione (GSH).

Abstract B32: Gedunin induces autophagy during mitosis, a novel form of mitotic catastrophe

Background: Breast Cancer is the most prevalent cancer in the world and the second leading cause of cancer death among women in the United States. Triple negative breast cancer (lacking estrogen receptors (ER), progesterone receptors (PR) and human epidermal growth factor receptor 2 (HER2)) can be extremely aggressive and is more likely to recur and metastasize than other subtypes of breast cancer. They are also unresponsive to the most effective receptor targeted treatments. A different treatment strategy is essential to fight against the triple negative breast cancer cells. Heat shock protein 90 (Hsp90) is a molecular chaperone that is required for the stability and function of various signaling proteins that promote the growth and/or survival of cancer cells. Several Hsp90 inhibitors are currently under clinical trial for the treatment of cancer. One natural HSP90 inhibitor is gedunin, which was isolated from the Indian neem tree (Azadirachta indica L.). Here we present our results of studies on the effect of gedunin on BT20 triple negative breast cancer cells and HMLE immortalized breast epithelial cells.

Method: BT20 and HMLE cells were grown according to ATCC guidelines. Flow cytometric analyses for cell death was performed using the Apoptosis/Necrosis detection kit (Roche). MDC incorporation and electron microscopic were performed to detect autophagy. BT20 tumor xenografts were used for determining the effect of gedunin in vivo. Real Time PCR, western blot and immunefluorescent studies were performed for determining gene expression.

Results: Gedunin induced a dose (0-20 μM) and time (0-72 h) dependent cytotoxicity, with significant inhibition of colony formation of BT20 cells at a concentration of 8 μM. However, gedunin did not affect the viability of HMLE cells. Cell cycle analyses demonstrated G2/M phase arrest of the BT20 cells. Electron microscopy studies revealed that gedunin induced the formation of autophagosomes, which was further confirmed by the monodansylcadaverine (MDC) incorporation. Real time-PCR and Western blot analyses revealed that gedunin induced the expression of autophagy related genes ATG5, ATG7, ATG12 and Beclin1. Furthermore, there was increased cleavage and lipidation of microtubule associated protein 1 light chain 3 (LC3B). Mechanistically, we have identified that gedunin induced phosphorylation of AMP kinase, which induces a signaling casade starting with phosphorylation of ULK1. This was suppressed when cells were either treated with an AMPK inhibitor Compound C or AMPK was downregulated with specific siRNA. There was also a reduction in gedunin-induces cell death. These data suggest that gedunin-mediated induction of autophagy occurs in part via the AMPK pathway. We have confirmed these findings in vivo using BT20 nude mice tumor xenografts. Intraperitoneal gedunin administration (5 mg.Kg bw) significantly decreased tumor growth. Western blot analyses showed increased expression of autophagic markers LC3B and Beclin1 in the gedunin-treated tissues which was further confirmed by the immunohistochemistry. More importantly, we observed increased number of autophagasomes in cells undergoing mitosis (p-Histone H3 staining).

Conclusion: Together, these data suggest that gedunin effectively drives triple negative breast cancer cells to an unusual form of mitotic catastrophe by inducing AMPK mediated autophagy during mitosis.

Citation Format: Parthasarathy Rangarajan, Prabhu Ramamoorthy, Satish Ramalingam, Dharmalingam Subramaniam, Sivapriya Ponnurangam, Scott Weir, Shrikant Anant, Roy Jensen. Gedunin induces autophagy during mitosis, a novel form of mitotic catastrophe. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr B32.

Abstract PR05: Effects of Hsp90 inhibitors on triple-negative breast cancer: Notch as a therapeutic target for stem cells

Background: Breast cancer is the second leading cause of death for woman. Within breast cancer subtypes, those classified as Triple Negative Breast Cancer (TNBC) exhibit dismal survival rates due to their propensity to develop distant metastases. Tumors contain heterogeneous cell populations and it has numerically rare cancer stem cells with indefinite proliferative potential that is responsible for tumor invasiveness, heterogeneity, and therapy resistance. Heat shock protein 90 (Hsp90) is a molecular chaperone that aids in the folding and maturation of various proteins involved in breast cancer progression and resistance to therapy. The aim of this study was to elucidate whether the two natural inhibitors of Hsp90, celastrol and triptolide inhibit triple negative breast cancer growth. Both these compounds are terpenoids and were obtained from the Chinese herb “Thunder God of Vine” (Tripterygium wilfordii).

Methods: BT20, BT549, MDA-MB-231 and MDA-MB-157 cells (all TNBC cells) were obtained and grown in DMEM containing 10% FBS as per ATCC recommendations. Cell proliferation was assessed by hexoseaminidase activity, and IC50 values calculated using GraphPad Prism5. For clonogenicity, 500 cells were treated with IC50 concentration of each compound for 24h, and then allowed to grow and form colonies. Mammosphere assay was performed using 5000 cells/ml in ultra low attachment plates. Images were captured after 5 days. For in vivo, BT20 cells were injected into flanks of athymic nude mice and treated with celastrol and triptolide at 3 mg/Kg bw and 0.25 mg/Kg bw, respectively.

Results: Celastrol and triptolide treatment suppressed the proliferation and colony formation ability of all four TNBC cell lines BT20, BT549, MDA-MB-231 and MDA-MB-157. Interestingly, the mammosphere assay (an assay used to evaluate the self-renewal capacity of the cancer stem cells) revealed that celastrol or triptolide significantly reduces the size and number of spheroids. Furthermore, expression of breast cancer stem cell markers ALDH1 and CD133 were significantly reduced in BT20 cells upon the treatment. Recently, Notch signaling has been shown to be critical for self-renewal of cancer stem cells. Activation of the Notch receptor, a membrane spanning receptor involves the interaction with a ligand resulting in a series of proteolytic cleavage events culminating in the release of the Notch intracellular domain (NICD). This NICD translocates to the nucleus, and together with its interacting partner CSL/RBPJ binds to cognate element and activates the expression of downstream target genes such as Hes-1. In cells treated with either celastrol or triptolide, there was a significant reduction in NICD, and its downstream target Hes-1. Furthermore, there was a reduction in ALDH+ cells. However, in cells where we ectopically overexpressed NICD, neither compound was as potent as control vector transfected cells in reducing proliferation, colony formation or mammosphere formation, suggesting the direct role for inhibiting Notch activation as a mechanism of action for the two compounds. We confirmed these finding in vivo using BT20 tumor xenografts grown in athymic nude mice. There was a reduction in the size of tumors in mice treated with celastrol or triptolide. In addition, western blot and immunohistochemistry analyses demonstrated a reduction in the number of ALDH+ and CD133+ cells.

Conclusion: Taken together these data suggest that both celastrol and triptolide affect cancer stem cells in TNBC, in part through inhibition of Notch signaling.

This abstract is also presented as Poster B31.

Citation Format: Prabhu Ramamoorthy, Sydney Byrne, Satish Ramalingam, Parthasarathy Rangarajan, Dharmalingam Subramaniam, Scott Weir, Shrikant Anant, Roy Jensen. Effects of Hsp90 inhibitors on triple-negative breast cancer: Notch as a therapeutic target for stem cells. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr PR05.

Methanolic extracts of bitter melon inhibit colon cancer stem cells by affecting energy homeostasis and autophagy

Bitter melon fruit is recommended in ancient Indian and Chinese medicine for prevention/treatment of diabetes. However its effects on cancer progression are not well understood. Here, we have determined the efficacy of methanolic extracts of bitter melon on colon cancer stem and progenitor cells. Both, whole fruit (BMW) and skin (BMSk) extracts showed significant inhibition of cell proliferation and colony formation, with BMW showing greater efficacy. In addition, the cells were arrested at the S phase of cell cycle. Moreover, BMW induced the cleavage of LC3B but not caspase 3/7, suggesting that the cells were undergoing autophagy and not apoptosis. Further confirmation of autophagy was obtained when western blots showed reduced Bcl-2 and increased Beclin-1, Atg 7 and 12 upon BMW treatment. BMW reduced cellular ATP levels coupled with activation of AMP activated protein kinase; on the other hand, exogenous additions of ATP lead to revival of cell proliferation. Finally, BMW treatment results in a dose-dependent reduction in the number and size of colonospheres. The extracts also decreased the expression of DCLK1 and Lgr5, markers of quiescent, and activated stem cells. Taken together, these results suggest that the extracts of bitter melon can be an effective preventive/therapeutic agent for colon cancer.

Curcumin induces cell death in esophageal cancer cells through modulating Notch signaling

Background

Curcumin inhibits the growth of esophageal cancer cell lines; however, the mechanism of action is not well understood. It is becoming increasingly clear that aberrant activation of Notch signaling has been associated with the development of esophageal cancer. Here, we have determined that curcumin inhibits esophageal cancer growth via a mechanism mediated through the Notch signaling pathway.

Methodology/Principal Findings

In this study, we show that curcumin treatment resulted in a dose and time dependent inhibition of proliferation and colony formation in esophageal cancer cell lines. Furthermore, curcumin treatment induced apoptosis through caspase 3 activation, confirmed by an increase in the ratio of Bax to Bcl2. Cell cycle analysis demonstrated that curcumin treatment induced cell death and down regulated cyclin D1 levels. Curcumin treatment also resulted in reduced number and size of esophagospheres. Furthermore, curcumin treatment led to reduced Notch-1 activation, expression of Jagged-1 and its downstream target Hes-1. This reduction in Notch-1 activation was determined to be due to the down-regulation of critical components of the γ-secretase complex proteins such as Presenilin 1 and Nicastrin. The combination of a known γ-secretase inhibitor DAPT and curcumin further decreased proliferation and induced apoptosis in esophageal cancer cells. Finally, curcumin treatment down-regulate the expressions of Notch-1 specific microRNAs miR-21 and miR-34a, and upregulated tumor suppressor let-7a miRNA.

Conclusion/Significance

Curcumin is a potent inhibitor of esophageal cancer growth that targets the Notch-1 activating γ-secretase complex proteins. These data suggest that Notch signaling inhibition is a novel mechanism of action for curcumin during therapeutic intervention in esophageal cancers.

Efficacy of occupant-collected dust samples in the evaluation of residential allergen and fungal levels

This study evaluated the ability of a resident to evaluate their home for allergens and mold using a settled dust test kit compared with evaluation and collection of settled dust by an industrial hygienist. Forty-three home residents were provided with a kit containing written instructions and a vacuum cleaner attachment for collecting a settled dust sample. Within 2 weeks of receiving the occupant-collected sample, an industrial hygienist evaluated these homes, including a visual inspection, collection of settled dust, and collection of spore trap samples. Settled dust samples were analyzed for major dog, cat, dust mite, and cockroach allergens using immunoassay methods, and for mold spore equivalents using quantitative polymerase chain reaction methods for the 13 mold species or species groups comprising the American Relative Moldiness Index (ARMI). Allergen concentrations and ARMIs were compared between the resident- and industrial hygienist-collected samples. Linear regression between the two sets of samples showed strong correlations for dog allergen (r(2) = 0.92) and cat allergen (r(2) = 0.90). Correlations for dust mite (r(2) = 0.57) and cockroach allergens (r(2) = 0.22) were lower, likely due to most samples being near the limit of detection. ARMIs were highly correlated (r(2) = 0.68) and were in categorical (high, medium, or low) agreement for 76% of residences. These results show that residents can reliably follow directions and collect settled dust samples, providing an efficient method to remotely screen homes for elevated allergen levels and to identify homes with a potential mold or moisture problem that may need further evaluation.

Reduced Expression of RNA Binding Protein CELF2, a Putative Tumor Suppressor Gene in Colon Cancer

BACKGROUND & AIMS

Colon cancer is the third leading cause of cancer death in both men and women in the United States. Every year, 160000 cases of colorectal cancer are diagnosed, and 57000 patients die. CUGBP, Elav-like family member 2 (CELF2) is an RNA binding protein that modulates various posttranscriptional events including RNA splicing, shuttling, editing, stability and translation. Previous studies have demonstrated that CELF2 expression is low in colon cancer cells. Furthermore, ectopic overexpression of CELF2 induces cells to undergo death by mitotic catastrophe. Based on the above observations, we hypothesized that CELF2 expression might be reduced during neoplastic transformation of colon cells.

METHODS

Forty human colon cancer tissues along with 10 uninvolved normal colon tissues from cancer patients were utilized for immunohistochemical analysis of CELF2 expression.

RESULTS

We have observed that CELF2 levels are reduced in colon tumor tissues when compared to the normal intestinal tissues. The data set suggests that RNA binding protein CELF2 could be a potential tumor suppressor protein. CELF2 was predominantly nuclear in normal cells, while the cancer tissues had diffused cytoplasmic staining.

CONCLUSION

CELF2 expression is consistently reduced during neoplastic transformation suggesting that it might play a crucial role in tumor initiation and progression.

Activation of NPY type 5 receptors induces a long-lasting increase in spontaneous GABA release from cerebellar inhibitory interneurons

Neuropeptide Y (NPY), a widely distributed neuropeptide in the central nervous system, can transiently suppress inhibitory synaptic transmission and alter membrane excitability via Y2 and Y1 receptors (Y2rs and Y1rs), respectively. Although many GABAergic neurons express Y5rs, the functional role of these receptors in inhibitory neurons is not known. Here, we investigated whether activation of Y5rs can modulate inhibitory transmission in cerebellar slices. Unexpectedly, application of NPY triggered a long-lasting increase in the frequency of miniature inhibitory postsynaptic currents in stellate cells. NPY also induced a sustained increase in spontaneous GABA release in cultured cerebellar neurons. When cerebellar cultures were examined for Y5r immunoreactivity, the staining colocalized with that of VGAT, a presynaptic marker for GABAergic cells, suggesting that Y5rs are located in the presynaptic terminals of inhibitory neurons. RT-PCR experiments confirmed the presence of Y5r mRNA in the cerebellum. The NPY-induced potentiation of GABA release was blocked by Y5r antagonists and mimicked by application of a selective peptide agonist for Y5r. Thus Y5r activation is necessary and sufficient to trigger an increase in GABA release. Finally, the potentiation of inhibitory transmission could not be reversed by a Y5r antagonist once it was initiated, consistent with the development of a long-term potentiation. These results indicate that activation of presynaptic Y5rs induces a sustained increase in spontaneous GABA release from inhibitory neurons in contrast to the transient suppression of inhibitory transmission that is characteristic of Y1r and Y2r activation. Our findings thus reveal a novel role of presynaptic Y5rs in inhibitory interneurons in regulating GABA release and suggest that these receptors could play a role in shaping neuronal network activity in the cerebellum.

Trafficking and fusion of neuropeptide Y-containing dense-core granules in astrocytes

It is becoming clear that astrocytes are active participants in synaptic functioning and exhibit properties, such as the secretion of classical transmitters, previously thought to be exclusively neuronal. Whether these similarities extend to the release of neuropeptides, the other major class of transmitters, is less clear. Here we show that cortical astrocytes can synthesize both native and foreign neuropeptides and can secrete them in a stimulation-dependent manner. Reverse transcription-PCR and mass spectrometry indicate that cortical astrocytes contain neuropeptide Y (NPY), a widespread neuronal transmitter. Immunocytochemical studies reveal NPY-immunoreactive (IR) puncta that colocalize with markers of the regulated secretory pathway. These NPY-IR puncta are distinct from the synaptic-like vesicles that contain classical transmitters, and the two types of organelles are differentially distributed. After activation of metabotropic glutamate receptors and the release of calcium from intracellular stores, the NPY-IR puncta fuse with the cell membrane, and the peptide-containing dense cores are displayed. To determine whether peptide secretion subsequently occurred, exocytosis was monitored from astrocytes expressing NPY-red fluorescent protein (RFP). In live cells, after activation of glutamate receptors, the intensity of the NPY-RFP-labeled puncta declined in a step-like manner indicating a regulated release of the granular contents. Because NPY is a widespread and potent regulator of synaptic transmission, these results suggest that astrocytes could play a role in the peptidergic modulation of synaptic signaling in the CNS.

Oxidative stress in the development of liver cirrhosis: a comparison of two different experimental models

BACKGROUND/AIMS

Oxidative stress has been implicated in liver cirrhosis. Carbon tetrachloride and thioacetamide are the most widely used models to develop cirrhosis in rats and the present study compares oxidative stress in the liver induced by these compounds at different stages of cirrhosis development.

METHODS

Twice-weekly intragastric or intraperitoneal administration of carbon tetrachloride or thioacetamide, respectively, produced liver cirrhosis after 3 months. Histology, serum markers and hepatic hydroxy proline content confirmed the cirrhosis.

RESULTS

An increase in oxidative stress parameters was seen in mitochondria, peroxisomes and microsomes from the liver after carbon tetrachloride or thioacetamide treatment. Oxidative stress was more severe in carbon tetrachloride treated animals than thioacetamide. Mild oxidative stress was evident at 1 and 2 months of treatment and a significant increase was seen by 3 months of treatment with either compound. By this time, frank liver cirrhosis was also observed.

CONCLUSIONS

These results suggest that evidence of oxygen free radicals is also found early in the development of fibrosis and cirrhosis in both models.

Renal damage in experimentally-induced cirrhosis in rats: Role of oxygen free radicals

Cirrhosis with ascites is associated with impaired renal function accompanied by sodium and water retention. Although it has been suggested that mediators such as nitric oxide play a role in the development of renal failure in this situation, other mechanisms underlying the process are not well understood. This study examined the role of oxidative stress in mediating renal damage during the development of cirrhosis in order to understand mechanisms involved in the process. It was shown that carbon tetrachloride- or thioacetamide-induced cirrhosis in rats results in oxidative stress in the kidney as seen by increased lipid peroxidation and protein oxidation, accompanied by altered antioxidant status. Cirrhosis was also found to affect renal mitochondrial function, as assessed by measurement of the respiratory control ratio, the swelling of mitochondria, and calcium flux across mitochondrial membranes. Increased lipid peroxidation and changes in lipid composition were evident in the renal brush border membranes, with compromised transport of 14C glucose across these membranes. In conclusion, renal alterations produced as a result of cirrhosis in the rat are possibly mediated by oxidative stress.

Intestinal mucosal alterations in rats with carbon tetrachloride-induced cirrhosis: changes in glycosylation and luminal bacteria

Spontaneous bacterial peritonitis is a major cause of mortality after liver cirrhosis. Altered permeability of the mucosa and deficiencies in host immune defenses through bacterial translocation from the intestine due to intestinal bacterial overgrowth have been implicated in the development of this complication. Molecular mechanisms underlying the process are not well known. In order to understand mechanisms involved in translocation of bacteria, this study explored the role of oxidative stress in mediating changes in intestinal mucosal glycosylation and luminal bacterial content during cirrhosis. CCl4-induced cirrhosis in rats led to prolonged oxidative stress in the intestine, accompanied by increased sugar content of both intestinal brush border and surfactant layers. This was accompanied by changes in bacterial flora in the gut, which showed increased hydrophobicity and adherence to the mucosa. Inhibition of xanthine oxidase using sodium tungstate or antioxidant supplementation using vitamin E reversed the oxidative stress, changes in brush border membrane sugar content, and bacterial adherence. In conclusion, oxidative stress in the intestine during cirrhosis alters mucosal glycosylation, accompanied by an increased hydrophobicity of luminal bacteria, enabling increased bacterial adherence onto epithelial cells. This might facilitate translocation across the mucosa, resulting in complications such as spontaneous bacterial peritonitis.

Mild whole-body heat stress alters retinoid metabolism in the rat small intestine

Mild heat treatment can modulate metabolism and prevent stress-induced alterations in cells and tissues. Retinoids are known to influence cellular metabolism and are essential for growth and differentiation, particularly of epithelial tissue. This study examines the effect of mild heat treatment on retinoid alterations in enterocytes in the rat small intestine. Heat treatment changed the differentiation pattern of enterocytes along the villus-crypt axis, accompanied by increases in retinol, retinaldehyde, and retinoic acid in proliferating crypt cells. Activities of retinoid metabolizing enzymes such as retinaldehyde oxidase and retinaldehyde reductase were also increased. These results suggest that mild heat treatment can alter retinoid metabolism in the small intestine, which might influence epithelial cell proliferation and differentiation.

Alterations in the intestinal glycocalyx and bacterial flora in response to oral indomethacin

Nonsteroidal anti-inflammatory drugs (NSAIDs), used extensively in clinical medicine, tend to cause adverse effects in the gastrointestinal tract. Earlier work has shown that oral administration of indomethacin produced oxidative damage in the small intestine and attenuation of the glycocalyx layer of the mucosa. The present study assessed, in greater detail, the alterations produced in the glycocalyx of rat small intestinal mucosa in response to indomethacin, with specific reference to surfactant-like particles (SLP) and brush border membranes (BBM). Changes in gut flora in response to the drug were also studied, as it has been shown that luminal bacteria play a role in the pathogenesis of NSAID-induced intestinal damage. The levels of sugars such as sialic acid, fucose, hexose and hexosamine were increased in SLP and decreased in the BBM following indomethacin treatment, with the effects being maximal 24h after the administration of the drug. The composition of lipids in the SLP was also found to be altered. There was a significant increase in the number of bacteria in the luminal contents of the small intestine and caecum in these animals, as compared with controls. The number of bacteria adherent to the intestinal mucosa was also significantly higher in the drug-treated group. In vitro studies revealed that there was an increased tendency for bacteria to adhere to SLP isolated from indomethacin-treated rats. These results suggest that alterations in glycosylation of SLP and BBM in response to indomethacin, along with qualitative and quantitative changes in the luminal bacterial flora, may facilitate translocation of bacteria into the mucosa. These changes may contribute to the enteropathy observed as a result of NSAID treatment.