Selective targeting of IRAK1 attenuates low molecular weight hyaluronic acid-induced stemness and non-canonical STAT3 activation in epithelial ovarian cancer

Advanced epithelial ovarian cancer (EOC) survival rates are dishearteningly low, with ~25% surviving beyond 5 years. Evidence suggests that cancer stem cells contribute to acquired chemoresistance and tumor recurrence. Here, we show that IRAK1 is upregulated in EOC tissues, and enhanced expression correlates with poorer overall survival. Moreover, low molecular weight hyaluronic acid, which is abundant in malignant ascites from patients with advanced EOC, induced IRAK1 phosphorylation leading to STAT3 activation and enhanced spheroid formation. Knockdown of IRAK1 impaired tumor growth in peritoneal disease models, and impaired HA-induced spheroid growth and STAT3 phosphorylation. Finally, we determined that TCS2210, a known inducer of neuronal differentiation in mesenchymal stem cells, is a selective inhibitor of IRAK1. TCS2210 significantly inhibited EOC growth in vitro and in vivo both as monotherapy, and in combination with cisplatin. Collectively, these data demonstrate IRAK1 as a druggable target for EOC.

DCLK1-Mediated Regulation of Invadopodia Dynamics and Matrix Metalloproteinase Trafficking Drives Invasive Progression in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a major health concern due to its high mortality from poor treatment responses and locoregional tumor invasion into life sustaining structures in the head and neck. A deeper comprehension of HNSCC invasion mechanisms holds the potential to inform targeted therapies that may enhance patient survival. We previously reported that doublecortin like kinase 1 (DCLK1) regulates invasion of HNSCC cells. Here, we tested the hypothesis that DCLK1 regulates proteins within invadopodia to facilitate HNSCC invasion. Invadopodia are specialized subcellular protrusions secreting matrix metalloproteinases that degrade the extracellular matrix (ECM). Through a comprehensive proteome analysis comparing DCLK1 control and shDCLK1 conditions, our findings reveal that DCLK1 plays a pivotal role in regulating proteins that orchestrate cytoskeletal and ECM remodeling, contributing to cell invasion. Further, we demonstrate in TCGA datasets that DCLK1 levels correlate with increasing histological grade and lymph node metastasis. We identified higher expression of DCLK1 in the leading edge of HNSCC tissue. Knockdown of DCLK1 in HNSCC reduced the number of invadopodia, cell adhesion and colony formation. Using super resolution microscopy, we demonstrate localization of DCLK1 in invadopodia and colocalization with mature invadopodia markers TKS4, TKS5, cortactin and MT1-MMP. We carried out phosphoproteomics and validated using immunofluorescence and proximity ligation assays, the interaction between DCLK1 and motor protein KIF16B. Pharmacological inhibition or knockdown of DCLK1 reduced interaction with KIF16B, secretion of MMPs, and cell invasion. This research unveils a novel function of DCLK1 within invadopodia to regulate the trafficking of matrix degrading cargo. The work highlights the impact of targeting DCLK1 to inhibit locoregional invasion, a life-threatening attribute of HNSCC.

Role of STAT3 in pancreatic cancer

Pancreatic cancer remains a serious and deadly disease, impacting people globally. There remain prominent gaps in the current understanding of the disease, specifically regarding the role of the signal transducer and activator of transcription (STAT) family of proteins in pancreatic tumors. STAT proteins, particularly STAT3, play important roles in pancreatic cancer, especially pancreatic ductal adenocarcinoma (PDAC), which is the most prevalent histotype. The role of STAT3 across a continuum of molecular processes, such as PDAC tumorigenesis and progression, immune escape, drug resistance and stemness, and modulation of the tumor microenvironment (TME), are only a tip of the iceberg. In some ways, the role of STAT3 in PDAC may hold greater importance than that of oncogenic Kirsten rat sarcoma virus (KRAS). This makes STAT3 a highly attractive target for developing targeted therapies for the treatment of pancreatic cancer. In this review, the current knowledge of STAT3 in pancreatic cancer has been summarized, particularly relating to STAT3 activation in cancer cells, cells of the TME, and the state of targeting STAT3 in pre-clinical and clinical trials of PDAC.

DNDI-6174 is a preclinical candidate for visceral leishmaniasis that targets the cytochrome bc1

New drugs for visceral leishmaniasis that are safe, low cost, and adapted to the field are urgently required. Despite concerted efforts over the last several years, the number of new chemical entities that are suitable for clinical development for the treatment of Leishmania remains low. Here, we describe the discovery and preclinical development of DNDI-6174, an inhibitor of Leishmania cytochrome bc1 complex activity that originated from a phenotypically identified pyrrolopyrimidine series. This compound fulfills all target candidate profile criteria required for progression into preclinical development. In addition to good metabolic stability and pharmacokinetic properties, DNDI-6174 demonstrates potent in vitro activity against a variety of Leishmania species and can reduce parasite burden in animal models of infection, with the potential to approach sterile cure. No major flags were identified in preliminary safety studies, including an exploratory 14-day toxicology study in the rat. DNDI-6174 is a cytochrome bc1 complex inhibitor with acceptable development properties to enter preclinical development for visceral leishmaniasis.

Acryl-3,5-bis(2,4-difluorobenzylidene)-4-piperidone targeting cellular JUN proto-oncogene, AP-1 transcription factor subunit inhibits head and neck squamous cell carcinoma progression

Aim

Head and neck squamous cell carcinoma (HNSCC) is the seventh most common cancer worldwide with a survival rate below fifty percent. Addressing meager therapeutic options, a series of small molecule inhibitors were screened for antitumor efficacy. The most potent analog, acryl-3,5-bis(2,4-difluorobenzylidene)-4-piperidone (DiFiD; A-DiFiD), demonstrated strong cellular JUN proto-oncogene, activator protein 1 (AP-1) transcription factor subunit (JUN, c-Jun) antagonism. c-Jun, an oncogenic transcription factor, promotes cancer progression, invasion, and adhesion; high (JUN) mRNA expression correlates with poorer HNSCC survival.

Methods

Four new small molecules were generated for cytotoxicity screening in HNSCC cell lines. A-DiFiD-treated HNSCC cells were assessed for cytotoxicity, colony formation, invasion, migration, and adhesion. Dot blot array was used to identify targets. Phospho-c-Jun (p-c-Jun) expression was analyzed using immunoblotting. The Cancer Genome Atlas (TCGA) head and neck cancer datasets were utilized to determine overall patient survival. The Clinical Proteomic Tumor Analysis Consortium (CPTAC) datasets interfaced with University of Alabama at Birmingham Cancer Data Analysis Portal (UALCAN) were analyzed to determine protein levels of c-Jun in HNSCC patients and correlate levels with patient.

Results

Of the small molecules tested, A-DiFiD was the most potent in HNSCC lines, while demonstrating low half-maximal drug inhibitory concentration (IC50) in non-malignant Het-1A cells. Additionally, A-DiFiD abrogated cell invasion, migration, and colony formation. Phospho-kinase in vitro array demonstrated A-DiFiD reduced p-c-Jun. Likewise, a time dependent reduction in p-c-Jun was observed starting at 3 min post A-DiFiD treatment. TCGA Firehose Legacy vs. recurrent and metastatic head and neck cancer reveal a nearly 3% DNA amplification in recurrent/metastatic tumor compared to below 1% in primary tumors that had no lymph node metastasis. CPTAC analysis show higher tumor c-Jun levels compared to normal. Patients with high JUN expression had significantly reduced 3-year survival.

Conclusions

A-DiFiD targets c-Jun, a clinical HNSCC driver, with potent anti-tumor effects.

CardioMotion: identification of functional and structural cardiotoxic liabilities in small molecules through brightfield kinetic imaging

Cardiovascular toxicity is an important cause of drug failures in the later stages of drug development, early clinical safety assessment, and even postmarket withdrawals. Early-stage in vitro assessment of potential cardiovascular liabilities in the pharmaceutical industry involves assessment of interactions with cardiac ion channels, as well as induced pluripotent stem cell-derived cardiomyocyte-based functional assays, such as calcium flux and multielectrode-array assays. These methods are appropriate for the identification of acute functional cardiotoxicity but structural cardiotoxicity, which manifests effects after chronic exposure, is often only captured in vivo. CardioMotion is a novel, label-free, high throughput, in vitro assay and analysis pipeline which records and assesses the spontaneous beating of cardiomyocytes and identifies compounds which impact beating. This is achieved through the acquisition of brightfield images at a high framerate, combined with an optical flow-based python analysis pipeline which transforms the images into waveform data which are then parameterized. Validation of this assay with a large dataset showed that cardioactive compounds with diverse known direct functional and structural mechanisms-of-action on cardiomyocytes are identified (sensitivity = 72.9%), importantly, known structural cardiotoxins also disrupt cardiomyocyte beating (sensitivity = 86%) in this method. Furthermore, the CardioMotion method presents a high specificity of 82.5%.

The Role of STATs in Ovarian Cancer: Exploring Their Potential for Therapy

Ovarian cancer (OvCa) is a deadly gynecologic malignancy that presents many clinical challenges due to late-stage diagnoses and the development of acquired resistance to standard-of-care treatment protocols. There is an increasing body of evidence suggesting that STATs may play a critical role in OvCa progression, resistance, and disease recurrence, and thus we sought to compile a comprehensive review to summarize the current state of knowledge on the topic. We have examined peer reviewed literature to delineate the role of STATs in both cancer cells and cells within the tumor microenvironment. In addition to summarizing the current knowledge of STAT biology in OvCa, we have also examined the capacity of small molecule inhibitor development to target specific STATs and progress toward clinical applications. From our research, the best studied and targeted factors are STAT3 and STAT5, which has resulted in the development of several inhibitors that are under current evaluation in clinical trials. There remain gaps in understanding the role of STAT1, STAT2, STAT4, and STAT6, due to limited reports in the current literature; as such, further studies to establish their implications in OvCa are necessitated. Moreover, due to the deficiency in our understanding of these STATs, selective inhibitors also remain elusive, and therefore present opportunities for discovery.

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 1529: Role of bitter taste receptor in colon cancer

Colorectal cancer (CRC) is a leading cause of cancer-related deaths in the US with 53,200 deaths projected in 2020. Although the disease affects older people, recent statistics show an increase in the younger population. CRC is a major problem in veterans and every year ~4,000 veterans are diagnosed with CRC within VA facilities. Hence, there is a dire need to identify novel signaling pathways as targets for therapy. Based on a bedside discovery in CRC patients, we observed that CRC patients complained about dysgeusia or taste alterations. There are 25 bitter taste receptors (TAS2R1-50, TAS2R60). Taste receptors utilize G-protein coupled receptors (GPCRs) and signal through calcium release. In preliminary studies, mining the Cancer Genome Atlas (TCGA) database, we have determined that TAS2R38 is upregulated in multiple cancers, including CRC. Moreover, the higher expression of TAS2R38 transcript in CRC compared to other cancers. Furthermore, we confirmed overexpression of TAS2R38 in CRC tissues and cell lines by immunohistochemistry and RT-PCR. Moreover, N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL), a TAS2R38 agonist, treatment activated calcium mobilization in HCT116 and DLD1 cells suggesting the functionality of the receptor. OdDHL also enhanced mRNA of interleukin (IL)-6 and IL-8 levels in the CRC cells. To determine whether expression of the receptor is affected in vivo, we conducted the dextran sodium sulfate (DSS)-induced acute colitis and colitis-associated cancer model (azoxymethane (AOM)-DSS) in C57BL/6 mice. TAS2R138, the mouse homolog of human TAS2R38 is overexpressed in crypt epithelial cells in the colitis and tumor tissues. These observations suggest that TAS2R38 is overexpressed in the CRC and may play a critical role in disease progression.

Citation Format: Krishan Jain, Sangita Bhattacharyya, Afreen Sayed, David Standing, Kathy Benich, Shahid Umar, Shrikant Anant, Scott Weir, Roy Jansen, Prasad Ravindra Dandawate. Role of bitter taste receptor in colon cancer [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 1529.

Abstract 5306: IRAK1: A novel TOLLway to target ovarian cancer

Ovarian cancer (OvCa) is the leading cause of gynecologic cancer-related deaths. While the overall response rate to first line therapy is encouraging (~80%), the majority of women develop recurrent disease that is characterized by resistance to chemotherapy. It is believed that cancer stem cells (CSCs) may contribute, in part, to resistance and recurrence of OvCa. To understand the pathways involved in enhancing this stem-like phenotype, we performed RNA sequencing. We identified that the TLR-ILR1 (TIR) pathways are highly activated in cisplatin resistant OvCa and in CSC-enriched 3-dimensional culture models. To further understand the role of the TIR pathway, we mined the Cancer Genome Atlas database and observed that interleukin receptor-associated kinase 1 (IRAK1), a critical mediator of TIR signaling is upregulated in cancer tissues. In addition, the locus surrounding the IRAK1 gene is amplified in 10% of OvCa patients. We confirmed that IRAK1 expression is upregulated in a majority of OvCa samples by immunohistochemistry of a tumor microarray consisting of 100 patient and paired non-cancerous fallopian tube tissues. Furthermore, this upregulation correlated with early cancer onset and shorter overall survival. To study the specific role of IRAK1 in OvCa, we knocked down its expression using specific shRNA. This significantly impaired cancer growth both in vitro in 2-dimension (2D) and 3-dimensional (3D) spheroid cultures, and in vivo in peritoneal disease models. Moreover, IRAK1 knockdown resulted in decreased expression of CSC marker genes, including MYC, ALDH1A1, DCLK1, and KLF4 suggesting a critical role in maintenance of stemness programming. Since IRAK1 is an upstream kinase that is activated by TIR receptors, we were intrigued by mechanisms driving its activation. In this regard, we have observed that low molecular weight hyaluronic acid (LMW HA) is present at high levels (100-200 ng/ml) in malignant ascites following peritoneal metastasis. Treatment of OVCAR8, A2780 and A1847 cells with LMW HA (50-200 ng/ml) induced IRAK1 phosphorylation at 80 ng/ml that was further enhanced at 200 ng/ml. In addition, LMW HA induced stemness and multidrug resistance genes. With additional studies using specific inhibitors, we identified that the increased spheroid formation occurred via a CD44-PKC-IRAK1-STAT3 signaling axis. Finally, using molecular modeling and in silico screening, coupled with Eurofin’s ScanMAX platform, we identified TCS2210 as a novel highly specific IRAK1 inhibitor. Also, TCS2210 abrogated LMW HA induced activation of IRAK1 and STAT3, and CSC marker genes MYC and DCLK1. Moreover, TCS2210 effectively suppressed OvCa cell growth in in vitro 2D and 3D cultures, and in peritoneal disease models alone and in combination with cisplatin. These data, taken together, strongly suggest that IRAK1 is a valid therapeutic target for OvCa.

Citation Format: David Standing, Sumedha Gunewardena, Afreen A. Sayed, Michele T. Pritchard, Harsh B. Pathak, Andrew K. Godwin, Shariska Petersen, Dineo Khabele, Jensen A. Roy, Prasad Dandawate, Scott J. Weir, Shrikant Anant. IRAK1: A novel TOLLway to target ovarian cancer [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 5306.

Abstract 2558: Determining the expression of RNA binding protein Rbm3 in tumor cells and immune cells in the tumor microenvironment in prostate cancer

Prostate cancer is the most common cancer among men. Currently, targeting the AR pathway, chemotherapy or immune-based therapies are major options but only provide a modest improvement in overall survival. RNA binding proteins have been shown to regulate AR expression in the progression of PCa. We and others have demonstrated that RNA binding protein RBM3 is upregulated in various solid tumors including PCa. We have also shown that RBM3 binds to 3’UTR of mRNAs of tumor-promoting factors and increases their mRNA stability and translation. However, the role of RBM3 in PCa is not well evaluated. We first analyzed the expression levels of RBM3 in the TCGA database. There was a significant increase in RBM3 expression even in cancers with a Gleason score of 6 upto Gleason 10 cancers. To confirm this we performed RT-PCR analyses of a prostate cancer cDNA panel. There was a significant increase in RBM3 expression in the PCa tissues compared to normal control. We used LNCaP and its derivative cell line C4-2B which show features of progressed disease such as metastatic capability and hormone independence. RT-PCR and western blot analyses demonstrated significantly higher RBM3 levels in C4-2B cells as compared to LNCaP cells suggesting a role for RBM3 in tumor progression. The tumor microenvironment also plays a very important role in prognosis of PCa. Specifically, tumor-associated macrophages (TAMs) have been shown to increase metastatic potential and increase tumor angiogenesis. To determine the levels of RBM3 expression and its effects on macrophage infiltration, we mined the TCGA database using TIMER2.0 software. There was a positive correlation of RBM3 expression with infiltration of both M1 and M2 macrophages. To further study the effect of interactions between PCa cells and TAMs, we used immortalized THP1 monocytes, which can be activated to M1 and M2 macrophages. We observed that just converting the THP1 cells to M1 or M2 macrophages increased RBM3 expression in both cell types. Also, when M1 and M2 macrophages were treated with conditioned media from LNCaP or C4-2B cells, there was an induction in the expression of RBM3. Similarly, when conditioned media from M0, M1, M2 activated THP1 cells were applied to LNCaP and C4-2B cells, there was an increase in RBM3 expression in the PCa cells. This suggests a positive cross-talk between the macrophages and PCa cells. We evaluated the cytokine profile in the conditioned media from M1 and M2 macrophages and determined that while M1 macrophages had increased levels of CXCL10, M2 macrophages showed higher levels of IL4 and IL10. Moreover, PCa cells have higher levels of CXCR3, the receptor for CXCL10. Together, these data suggest that crosstalk between TAMs and cancer cells in the PCA microenvironment plays a significant role in increasing RBM3 expression, which in turn enhances global translation of disease progression related genes.

Citation Format: Afreen Asif Ali Sayed, David Standing, Prasad Dandawate, Shahid Umar, Roy Jensen, Rahul Parikh, John Taylor, Shrikant Anant. Determining the expression of RNA binding protein Rbm3 in tumor cells and immune cells in the tumor microenvironment in prostate cancer [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 2558.

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.

Prolactin receptor signaling: A novel target for cancer treatment - Exploring anti-PRLR signaling strategies

Prolactin (PRL) is a peptide hormone mainly secreted from the anterior pituitary gland. PRL is reported to play a role in pregnancy, mammary gland development, immune modulation, reproduction, and differentiation of islet cells. PRL binds to its receptor PRLR, which belongs to a superfamily of the class I cytokine receptor that has no intrinsic kinase activity. In canonical signaling, PRL binding to PRLR induces downstream signaling including JAK-STAT, AKT and MAPK pathways. This leads to increased cell proliferation, stemness, migration, apoptosis inhibition, and resistance to chemotherapy. PRL-signaling is upregulated in numerous hormone-dependent cancers including breast, prostate, ovarian, and endometrial cancer. However, more recently, the pathway has been reported to play a tumor-promoting role in other cancer types such as colon, pancreas, and hepatocellular cancers. Hence, the signaling pathway is an attractive target for drug development with blockade of the receptor being a potential therapeutic approach. Different strategies have been developed to target this receptor including modification of PRL peptides (Del1-9-G129R-hPRL, G129R-Prl), growth hormone receptor/prolactin receptor bispecific antibody antagonist, neutralizing antibody LFA102, an antibody-drug conjugate (ABBV-176) of the humanized antibody h16f (PR-1594804) and pyrrolobenzodiazepine dimer, a bispecific antibody targeting both PRLR and CD3, an in vivo half-life extended fusion protein containing PRLR antagonist PrlRA and albumin binding domain. There have also been attempts to discover and develop small molecular inhibitors targeting PRLR. Recently, using structure-based virtual screening, we identified a few antipsychotic drugs including penfluridol as a molecule that inhibits PRL-signaling to inhibit PDAC tumor progression. In this review, we will summarize the recent advances in the biology of this receptor in cancer and give an account of PRLR antagonist development for the treatment of cancer.

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.

Cucurbitacin B and I inhibits colon cancer growth by targeting the Notch signaling pathway

Cancer stem cells (CSCs) have the ability to self-renew and induce drug resistance and recurrence in colorectal cancer (CRC). As current chemotherapy doesn’t eliminate CSCs completely, there is a need to identify novel agents to target them. We investigated the effects of cucurbitacin B (C-B) or I (C-I), a natural compound that exists in edible plants (bitter melons, cucumbers, pumpkins and zucchini), against CRC. C-B or C-I inhibited proliferation, clonogenicity, induced G₂/M cell-cycle arrest and caspase-mediated-apoptosis of CRC cells. C-B or C-I suppressed colonosphere formation and inhibited expression of CD44, DCLK1 and LGR5. These compounds inhibited notch signaling by reducing the expression of Notch 1–4 receptors, their ligands (Jagged 1-2, DLL1,3,4), γ-secretase complex proteins (Presenilin 1, Nicastrin), and downstream target Hes-1. Molecular docking showed that C-B or C-I binds to the ankyrin domain of Notch receptor, which was confirmed using the cellular thermal shift assay. Finally, C-B or C-I inhibited tumor xenograft growth in nude mice and decreased the expression of CSC-markers and notch signaling proteins in tumor tissues. Together, our study suggests that C-B and C-I inhibit colon cancer growth by inhibiting Notch signaling pathway.

The Histone Demethylase KDM3A, Increased in Human Pancreatic Tumors, Regulates Expression of DCLK1 and Promotes Tumorigenesis in Mice

BACKGROUND & AIMS

The histone lysine demethylase 3A (KDM3A) demethylates H3K9me1 and H3K9Me2 to increase gene transcription and is upregulated in tumors, including pancreatic tumors. We investigated its activities in pancreatic cancer cell lines and its regulation of the gene encoding doublecortin calmodulin-like kinase 1 (DCLK1), a marker of cancer stem cells.

METHODS

We knocked down KDM3A in MiaPaCa-2 and S2-007 pancreatic cancer cell lines and overexpressed KDM3A in HPNE cells (human noncancerous pancreatic ductal cell line); we evaluated cell migration, invasion, and spheroid formation under hypoxic and normoxic conditions. Nude mice were given orthotopic injections of S2-007 cells, with or without (control) knockdown of KDM3A, and HPNE cells, with or without (control) overexpression of KDM3A; tumor growth was assessed. We analyzed pancreatic tumor tissues from mice and pancreatic cancer cell lines by immunohistochemistry and immunoblotting. We performed RNA-sequencing analysis of MiaPaCa-2 and S2-007 cells with knockdown of KDM3A and evaluated localization of DCLK1 and KDM3A by immunofluorescence. We analyzed the cancer genome atlas for levels of KDM3A and DCLK1 messenger RNA in human pancreatic ductal adenocarcinoma (PDAC) tissues and association with patient survival time.

RESULTS

Levels of KDM3A were increased in human pancreatic tumor tissues and cell lines, compared with adjacent nontumor pancreatic tissues, such as islet and acinar cells. Knockdown of KDM3A in S2-007 cells significantly reduced colony formation, invasion, migration, and spheroid formation, compared with control cells, and slowed growth of orthotopic tumors in mice. We identified KDM3A-binding sites in the DCLK1 promoter; S2-007 cells with knockdown of KDM3A had reduced levels of DCLK1. HPNE cells that overexpressed KDM3A formed foci and spheres in culture and formed tumors and metastases in mice, whereas control HPNE cells did not. Hypoxia induced sphere formation and increased levels of KDM3A in S2-007 cells and in HPNE cells that overexpressed DCLK1, but not control HPNE cells. Levels of KDM3A and DCLK1 messenger RNA were higher in human PDAC than nontumor pancreatic tissues and correlated with shorter survival times of patients.

CONCLUSIONS

We found human PDAC samples and pancreatic cancer cell lines to overexpress KDM3A. KDM3A increases expression of DCLK1, and levels of both proteins are increased in human PDAC samples. Knockdown of KDM3A in pancreatic cancer cell lines reduced their invasive and sphere-forming activities in culture and formation of orthotopic tumors in mice. Hypoxia increased expression of KDM3A in pancreatic cancer cells. Strategies to disrupt this pathway might be developed for treatment of pancreatic cancer.

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.

Abstract 2953: Notch signaling is a key pathway involved in drug resistance in melanoma cells

Background: Melanoma expresses a plastic and aggressive phenotype, lacking the majority of regulatory mechanisms due to the aberrant activation of various signaling pathways including the Notch pathway. Oncogenic BRAF mutation has the target for therapeutic interventions such as the drug vemurafinib but recent studies have indicated development of resistance. Unfortunately, however, the mechanisms of vemurafenib-induced resistance in melanoma are still poorly understood. We explored the role of Notch signaling in development of vemurafenib drug resistance in melanoma cells.

Methods: We have utilized melanoma cell lines (especially B16/F10, SKMEL-28, A2058, UACC275 SKMEL103 and M14) with and without the common hot spot BRAFV600E mutation for the studies. We performed hexoseaminidase and clonogenicity assays to determine the cell growth rate and IC50 values in the cell lines. To generate drug resistant cells, UACC275 and SKMEL-28 cells were repetitively grown in the presence of vemurafenib. For stem cells, we did melanosphere formation assay. For protein expression, we performed western blots.

Results: In the initial screening with vemurafinib, we observed a pattern of increased IC50 values in drug resistant cell lines, with UACC275 and SKMEL-28 being the more sensitive cells. Following sequential exposure, we developed vemurafinib-resistant cell lines, and observed that the IC50 values for proliferation inhibition to be ∼8-10 fold higher than the parental cells. Colony forming potential of the drug resistant cells was also not affected by increasing concentrations of vemurafenib, confirming acquisition of resistance. Furthermore, the drug resistant UACC275 cells presented a smaller and round morphology compared to the usual elongated and stretched appearance of the parent lines. Additionally, we also observed a significant increase in size of melanospheres for the drug resistance cells suggesting enrichment of stem cells. We further studied the expression and activation of various notch signaling cascade proteins and observed a significant increase in the levels of cleaved Notch-2, and -4 in the drug resistant cells. Interestingly, early passages of cell culture for drug resistant cells showed decrease in cleaved Notch-2 levels in cells with significant increase in basal levels of cleaved Notch-2 levels at <10 passages. Therefore, a reductionist model of vemurafenib resistance can be developed using the UACC275 and SKMEL-28 cell line.

Conclusion: As Notch-2 and -4 levels were higher in most of the resistant cells, therefore, notch signaling may play critical role in the development of vemurafenib drug resistance in melanoma cells. Targeting specific notch in patients on chemotherapy especially on BRAF inhibitors will be a key event for better progression and treatment of melanoma.

Citation Format: Gaurav Kaushik, Jonathan Sheldon, Prasad Dandawate, Dharmalingam Subramaniam, David Standing, Shrikant Anant, Joshua M.V. Mammen. Notch signaling is a key pathway involved in drug resistance in melanoma 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 2953.

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.

Bitter melon extracts enhance the activity of chemotherapeutic agents through the modulation of multiple drug resistance

Recently, we demonstrated that extracts of bitter melon (BME) can be used as a preventive/therapeutic agent in colon cancers. Here, we determined BME effects on anticancer activity and bioavailability of doxorubicin (DOX) in colon cancer cells. BME enhanced the effect of DOX on cell proliferation and sensitized the cells toward DOX upon pretreatment. Furthermore, there was both increased drug uptake and reduced drug efflux. We also observed a reduction in the expression of multidrug resistance conferring proteins (MDRCP) P-glycoprotein, MRP-2, and BCRP. Further BME suppressed DOX efflux in MDCK cells overexpressing the three efflux proteins individually, suggesting that BME is a potent inhibitor of MDR function. Next, we determined the effect of BME on PXR, a xenobiotic sensing nuclear receptor and a transcription factor that controls the expression of the three MDR genes. BME suppressed PXR promoter activity thereby suppressing its expression. Finally, we determined the effect of AMPK pathway on drug efflux because we have previously demonstrated that BME affects the pathway. However, inhibiting AMPK did not affect drug resistance, suggesting that BME may use different pathways for the anticancer and MDR modulating activities. Together, these results suggest that BME can enhance the bioavailability and efficacy of conventional chemotherapy.

Abstract 972: Bitter melon extracts enhance the activity of chemotherapeutic agents through the modulation of multiple drug resistance

Purpose: Bitter melon (BM) is a tropical and subtropical vine, widely grown in Asia, Africa, and the Caribbean for its edible fruit. The fruit is recommended in ancient Indian and Chinese medicine for prevention/treatment of diabetes. Recent publications have demonstrated that BM extracts inhibit the growth of breast and prostate cancers. Our previous studies also suggest that it can be used as a preventive/therapeutic agent in colon cancers. Phytochemical usage and dietary supplementation can often lead to improved efficacy of conventional therapies but they may also lead to drug-drug interactions. Thus, we studied the effects of bitter melon on the anticancer activity as well as bioavailability of doxorubicin (DOX) in colon cancer cells (SW480 and HT29)

Methods: Cell proliferation studies using DOX were carried out in colon cancer cells either pretreated or co-treated with BM extract. To identify the effects of BM on active permeation of DOX drug uptake and efflux studies were carried out in colon cancer cells. PCR and western blots were performed to determine the changes in major efflux protein levels involved in limiting the uptake of DOX in cancer cells. Further, luciferase based activity assays for PXR, a xenobiotic sensing nuclear receptor were performed to identify the mechanism with which BM altered the efflux transporter expression.

Results: BM was found to enhance the effect of DOX as well as sensitize the cells towards DOX upon pretreatment. Combinatorial index was calculated to identify synergism between the therapeutics. This effect may be result of altered drug permeation into the cells as both drug uptake and efflux were found to reduce in the presence of BM pre- and co- treatment. The reduced efflux and uptake maybe due to inhibition as well as alteration in expression of expression of Multidrug resistance genes (P-glycoprotein, MRP-2 and BCRP) as was observed with PCR and western blots. The BM extracts were seen to effect PXR activation as well as expression in colon cancer cells which might be responsible for the altered efflux protein expression. Since AMPK pathway is the main target of BM we also studied the effect of other AMPK activators to see whether there is a correlation between AMPK pathway and efflux. Our results were interesting in showing potential correlation between AMPK pathway and drug efflux.

Conclusion: Taken together these results suggest that BM can enhance the bioavailability and efficacy of conventional chemotherapy. This can lead to reduction in minimum effective doses of chemotherapeutics thereby reducing toxicity/side effects.

Citation Format: Deep Kwatra, Dharmalingam Subramaniam, David Standing, Ashim K. Mitra, Shrikant Anant. Bitter melon extracts enhance the activity of chemotherapeutic agents through the modulation of multiple drug resistance. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 972. doi:10.1158/1538-7445.AM2013-972

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.

Tandutinib inhibits the Akt/mTOR signaling pathway to inhibit colon cancer growth

The c-Kit receptor can activate distinct signaling pathways including phosphoinositide 3-kinase (PI3K)/Akt and mTOR. Aberrant c-Kit activation protects cells from apoptosis and enhances invasion of colon carcinoma cells. Tandutinib is a novel quinazoline-based inhibitor of the type III receptor tyrosine kinases including c-Kit. We determined the effect of tandutinib on colon cancer growth and identified a mechanism of action. Tandutinib inhibited phosphorylation of c-Kit, Akt, mTOR, and p70S6 kinase. In addition, tandutinib significantly inhibited the proliferation and colony formation ability of colon cancer cell lines but did not affect normal colonic epithelial cells. There were increased levels of activated caspase-3 and Bax/Bcl2 ratio, coupled with a reduction in cyclin D1, suggesting apoptosis. There was also a downregulation of COX-2, VEGF, and interleukin-8 expression, suggesting effects on cancer-promoting genes. In addition, overexpressing constitutively active Akt partially suppressed tandutinib-mediated colon cancer cell growth. In vivo, intraperitoneal administration of tandutinib significantly suppressed growth of colon cancer tumor xenografts. There was a reduction in CD31-positive blood vessels, suggesting that there was an effect on angiogenesis. Tandutinib treatment also inhibited the expression of cancer-promoting genes COX-2 and VEGF and suppressed the activation of Akt/mTOR signaling proteins in the xenograft tissues. Together, these data suggest that tandutinib is a novel potent therapeutic agent that can target the Akt/mTOR/p70S6K signaling pathway to inhibit tumor growth and angiogenesis.

Abstract 5287: RNA binding protein RBM3 promotes metastasis through induction of hemangiogenesis and lymphangiogenesis

Introduction: Tumor metastasis, rather than primary tumors is the main cause of cancer-related deaths. A critical aspect of tumor metastasis, driven by vascular endothelial growth factors (VEGF) is the development of new vessels through hemangiogenesis and lymphangiogenesis. RNA binding protein RBM3 is a novel protooncogene that transforms normal cells when overexpressed. Here, we report that RBM3 mediates both hemangiogenesis and lymphangiogenesis. Results: Immunohistochemistry analysis of a human tissue microarray demonstrated increased RBM3 expression in tumors when compared to normal tissue, with even higher levels in metastatic tissues. Furthermore, RBM3-transformed NIH3T3 cells were injected into flanks of athymic nude mice metastasized to the liver and lungs. Immunohistochemistry analysis of the primary NIH3T3-RBM3 xenograft demonstrated increased number of microvessels that were lined by either CD31 or LYVE1 positive cells suggesting the increase in hem- and lymphangiogenesis. To demonstrate that RBM3 induces hemangiogenesis, tube formation assay using human umbilical vein endothelial (HUVEC) cells was performed. RBM3 overexpression increased, while RBM3 knockdown inhibited tube formation. Furthermore, NIH3T3-RBM3 cells significantly induced de novo capillary formation in the Chorio-Allantoic Membrane assay. Similarly, RBM3 overexpression enhanced, while knockdown suppressed tube formation by human lymphatic endothelial (HLEC) cells suggesting that it also affects lymphangiogenesis. To confirm the RBM3 role in hem- and lymphangiogenesis, HCT116 conditioned media was used in the tube formation assays. Tube formation by both HUVEC and HLEC cells was significantly increased in media from HCT116-RBM3 overexpressing cells. Moreover, both HUVEC and HLEC cells showed significant migration through collagen in transwell invasion assay. We further determined that this was due to the increased expression of VEGF A, VEGF C and VEGF D because siRNA mediated suppression of either one of these factors significantly reduced RBM3-mediated enhanced HLEC tube formation and migration through collagen. We next determined the mechanism of RBM3 mediated upregulation of the three VEGFs. HCT116 cells overexpressing RBM3 showed increased steady state levels of VEGF A, C and D mRNAs when compared to control. In addition, actinomycin D-stability assays demonstrated that there was increased stability of the three VEGF mRNAs in HCT116-RBM3 cells when compared to HCT116 control cells. Conclusion: Taken together these data suggests that RBM3 is a key regulator of hemangiogenesis and lymphangiogenesis, thereby inducing a highly metastatic phenotype through upregulation of VEGF A, C and D at the posttranscriptional levels of mRNA stability and translation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5287. doi:1538-7445.AM2012-5287

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.

Overexpression of hippocampal Ca2+/calmodulin-dependent protein kinase II improves spatial memory

Hippocampal alpha-calcium/calmodulin-dependent protein kinase II (alphaCaMKII) has been implicated in neuronal plasticity and spatial learning. In the present experiment, an adeno-associated virus (AAV) vector was designed to express alphaCaMKII driven by the U6 promotor. Microinfusion of this vector into the rat hippocampus increased alphaCaMKII immunoreactivity by approximately 73% (Western analysis) and improved performance in a water maze task. Locomotor activity and exploratory behavior in an open field task were not altered by the overexpression of alphaCaMKII. These data support a role for alphaCaMKII in spatial or explicit memory storage. The advantages of viral vectors for manipulating target proteins expression compared with genetically modified mouse models are discussed.

Influence of nematodes on resource utilization by bacteria--an in vitro study

The positive influence of bacterial feeding nematodes on bacterial mediated processes such as organic matter mineralization and nutrient cycling is widely accepted, but the mechanisms of these interactions are not always apparent. Both transport of bacteria by nematodes, and nutritional effects caused by nematode N excretion are thought to be involved, but their relative importance is not known because of the difficulties in studying these interactions in soil. We developed a simple in vitro assay to study complex nematode/bacterial interactions and used it to conduct a series of experiments to determine the potential influence of nematode movement and nutritional effects on bacterial resource use. The system used bacterial feeding and nonfeeding insect parasitic nematodes, and luminescent bacteria marked with metabolic reporter genes. Both nutritional enhancement of bacterial activity and bacterial transport were observed and we hypothesize that in nature, the relative importance of transport is likely to be greater in bulk soil, whereas nematode excretion may have greater impact in the rhizosphere. In both cases, the ability of nematodes to enhance bacterial resource utilization has implications for soil components of biogeochemical cycling.

In vivo inhibition of hippocampal Ca2+/calmodulin-dependent protein kinase II by RNA interference

Hippocampal alpha-Ca2+/calmodulin-dependent protein kinase II (alpha-CaMKII) has been implicated in spatial learning, neuronal plasticity, epilepsy, and cerebral ischemia. In the present study, an adeno-associated virus (AAV) vector was designed to express green fluorescent protein (GFP) from the CBA promoter and a small hairpin RNA targeting alpha-CaMKII (AAV-shCAM) driven from the U6 promoter. The AAV-shCAM or control vector was microinfused into the rat hippocampus and behavioral testing conducted 19-26 days following surgery. Expression of the marker gene and alpha-CaMKII was evaluated 31 days following AAV infusion. GFP expression was localized to the hippocampus and extended +/-2 mm rostral and caudal from the injection site. Hippocampal alpha-CaMKII was significantly reduced following AAV-shCAM treatment as demonstrated using immunohistochemical and Western analysis. This suppression of alpha-CaMKII was associated with changes in exploratory behavior (open field task) and impaired place learning (water maze task). These results demonstrate the efficacy of a viral-based delivered shRNA to produce gene suppression in a specific circuit of the brain.