Medicine and Health Sciences Commons^™

A Review Of Isomirs In Colorectal Cancer, Molly A. Lausten, Bruce M. Boman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

As advancements in sequencing technology rapidly continue to develop, a new classification of microRNAs has occurred with the discovery of isomiRs, which are relatively common microRNAs with sequence variations compared to their established template microRNAs. This review article seeks to compile all known information about isomiRs in colorectal cancer (CRC), which has not, to our knowledge, been gathered previously to any great extent. A brief overview is given of the history of microRNAs, their implications in colon cancer, the canonical pathway of biogenesis and isomiR classification. This is followed by a comprehensive review of the literature that is available on …

Guanylyl Cyclase C As A Diagnostic And Therapeutic Target In Colorectal Cancer, Adi Caspi, Ariana A. Entezari, Madison Crutcher, Adam E. Snook, Scott A. Waldman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

Colorectal cancer remains a major cause of mortality in the USA, despite advances in prevention and screening. Existing therapies focus primarily on generic treatment such as surgical intervention and chemotherapy, depending on disease severity. As personalized medicine and targeted molecular oncology continue to develop as promising treatment avenues, there has emerged a need for effective targets and biomarkers of colorectal cancer. The transmembrane receptor guanylyl cyclase C (GUCY2C) regulates intestinal homeostasis and has emerged as a tumor suppressor. Further, it is universally expressed in advanced metastatic colorectal tumors, as well as other cancer types that arise through intestinal metaplasia. In …

Targeting Gastrointestinal Cancers With Chimeric Antigen Receptor (Car)-T Cell Therapy, Ross E Staudt, Robert D Carlson, Adam E. Snook

Department of Pharmacology and Experimental Therapeutics Faculty Papers

The immune system is capable of remarkably potent and specific efficacy against infectious diseases. For decades, investigators sought to leverage those characteristics to create immune-based therapies (immunotherapy) that might be far more effective and less toxic than conventional chemotherapy and radiation therapy for cancer. Those studies revealed many factors and mechanisms underlying the success or failure of cancer immunotherapy, leading to synthetic biology approaches, including CAR-T cell therapy. In this approach, patient T cells are genetically modified to express a chimeric antigen receptor (CAR) that converts T cells of any specificity into tumor-specific T cells that can be expanded to …

Apc-Β-Catenin-Tcf Signaling Silences The Intestinal Guanylin-Gucy2c Tumor Suppressor Axis., Erik S Blomain, Jeffrey A Rappaport, Amanda M Pattison, Babar Bashir, Ellen Caparosa, Jonathan Stem, Adam E Snook, Scott A Waldman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

Sporadic colorectal cancer initiates with mutations in APC or its degradation target β-catenin, producing TCF-dependent nuclear transcription driving tumorigenesis. The intestinal epithelial receptor, GUCY2C, with its canonical paracrine hormone guanylin, regulates homeostatic signaling along the crypt-surface axis opposing tumorigenesis. Here, we reveal that expression of the guanylin hormone, but not the GUCY2C receptor, is lost at the earliest stages of transformation in APC-dependent tumors in humans and mice. Hormone loss, which silences GUCY2C signaling, reflects transcriptional repression mediated by mutant APC-β-catenin-TCF programs in the nucleus. These studies support a pathophysiological model of intestinal tumorigenesis in which mutant APC-β-catenin-TCF transcriptional regulation …

Silencing The Guca2a-Gucy2c Tumor Suppressor Axis In Cin, Serrated, And Msi Colorectal Neoplasia., Babar Bashir, Dante J. Merlino, Jeff A. Rappaport, Esteban Gnass, Juan P. Palazzo, Ying Feng, Eric R R. Fearon, Adam E. Snook, Scott A. Waldman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

Colorectal cancers (CRCs) initiate through distinct mutations, including in APC pathway components leading to tubular adenomas (TAs); in BRAF, with epigenetic silencing of CDX2, leading to serrated adenomas (SAs); and in the DNA mismatch repair machinery driving microsatellite instability (MSI). Transformation through the APC pathway involves loss of the hormone GUCA2A that silences the tumor-suppressing receptor GUCY2C. Indeed, oral hormone replacement is an emerging strategy to reactivate GUCY2C and prevent CRC initiation and progression. Moreover, retained expression by tumors arising from TAs has established GUCY2C as a diagnostic and therapeutic target to prevent and treat metastatic CRC. Here, we defined …

Split Tolerance Permits Safe Ad5-Gucy2c-Padre Vaccine-Induced T-Cell Responses In Colon Cancer Patients., Adam E. Snook, Trevor R. Baybutt, Bo Xiang, Tara S. Abraham, John C. Flickinger, Terry Hyslop, Tingting Zhan, Walter K. Kraft, Takami Sato, Scott A. Waldman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

Background: The colorectal cancer antigen GUCY2C exhibits unique split tolerance, evoking antigen-specific CD8+, but not CD4+, T-cell responses that deliver anti-tumor immunity without autoimmunity in mice. Here, the cancer vaccine Ad5-GUCY2C-PADRE was evaluated in a first-in-man phase I clinical study of patients with early-stage colorectal cancer to assess its safety and immunological efficacy.

Methods: Ten patients with surgically-resected stage I or stage II (pN0) colon cancer received a single intramuscular injection of 1011 viral particles (vp) of Ad5-GUCY2C-PADRE. Safety assessment and immunomonitoring were carried out for 6 months following immunization. This trial employed continual monitoring of both efficacy and toxicity …

The Anti-Cancer Effect Of Retinoic Acid Signaling In Crc Occurs Via Decreased Growth Of Aldh+ Colon Cancer Stem Cells And Increased Differentiation Of Stem Cells, Shirin R. Modarai, Anindita Gupta, Lynn M. Opdenaker, Ryan Kowash, Gabriel Masters, Vignesh Viswanathan, Tao Zhang, Jeremy Z. Fields, Bruce M. Boman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

Background: Tumorigenesis is driven by stem cell (SC) overpopulation. BecauseALDH is both a marker for SCs in many tissues and a key enzyme in retinoid acid (RA)signaling, we studied RA signaling in normal and malignant colonic SCs.Hypothesis: RA signaling regulates growth and differentiation of ALDH+ colonicSCs dysregulation of RA signaling contributes to SC overpopulation and colorectalcancer (CRC) development.Methods: We analyzed normal and malignant colonic tissues and CRC cell linesto see if retinoid receptors (RXR &RAR) are exclusively expressed in ALDH+ SCs,and if RA signaling changes during CRC development. We determined whether RAsignaling regulates cancer SC (CSC) proliferation, differentiation, sphere formation,and …

The Guanylate Cyclase C-Cgmp Signaling Axis Opposes Intestinal Epithelial Injury And Neoplasia., Jeffrey A. Rappaport, Scott A. Waldman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

Guanylate cyclase C (GUCY2C) is a transmembrane receptor expressed on the luminal aspect of the intestinal epithelium. Its ligands include bacterial heat-stable enterotoxins responsible for traveler's diarrhea, the endogenous peptide hormones uroguanylin and guanylin, and the synthetic agents, linaclotide, plecanatide, and dolcanatide. Ligand-activated GUCY2C catalyzes the synthesis of intracellular cyclic GMP (cGMP), initiating signaling cascades underlying homeostasis of the intestinal epithelium. Mouse models of GUCY2C ablation, and recently, human populations harboring GUCY2C mutations, have revealed the diverse contributions of this signaling axis to epithelial health, including regulating fluid secretion, microbiome composition, intestinal barrier integrity, epithelial renewal, cell cycle progression, responses …

The Heat-Stable Enterotoxin Receptor, Guanylyl Cyclase C, As A Pharmacological Target In Colorectal Cancer Immunotherapy: A Bench-To-Bedside Current Report., Trevor R. Baybutt, Allison A. Aka, Adam E. Snook

Department of Pharmacology and Experimental Therapeutics Faculty Papers

Cancer immunotherapy is becoming a routine treatment modality in the oncology clinic, in spite of the fact that it is a relatively nascent field. The challenge in developing effective immunotherapeutics is the identification of target molecules that promote anti-tumor efficacy across the patient population while sparing healthy tissue from damaging autoimmunity. The intestinally restricted receptor guanylyl cyclase C (GUCY2C) is a target that has been investigated for the treatment of colorectal cancer and numerous animal, and clinical studies have demonstrated both efficacy and safety. Here, we describe the current state of GUCY2C-directed cancer immunotherapy and the future directions of this …

St-Producing E. Coli Oppose Carcinogen-Induced Colorectal Tumorigenesis In Mice., Peng Li, Jieru E. Lin, Adam E. Snook, Scott A. Waldman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

There is a geographic inequality in the incidence of colorectal cancer, lowest in developing countries, and greatest in developed countries. This disparity suggests an environmental contribution to cancer resistance in endemic populations. Enterotoxigenic bacteria associated with diarrheal disease are prevalent in developing countries, including enterotoxigenic E. coli (ETEC) producing heat-stable enterotoxins (STs). STs are peptides that are structurally homologous to paracrine hormones that regulate the intestinal guanylyl cyclase C (GUCY2C) receptor. Beyond secretion, GUCY2C is a tumor suppressor universally silenced by loss of expression of its paracrine hormone during carcinogenesis. Thus, the geographic imbalance in colorectal cancer, in part, may …

Guanylate Cyclase C As A Target For Prevention, Detection, And Therapy In Colorectal Cancer., Allison A. Aka, Jeff A. Rappaport, Amanda M. Pattison, Takami Sato, Adam E. Snook, Scott A. Waldman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

INTRODUCTION: Colorectal cancer remains the second leading cause of cancer death in the United States, and new strategies to prevent, detect, and treat the disease are needed. The receptor, guanylate cyclase C (GUCY2C), a tumor suppressor expressed by the intestinal epithelium, has emerged as a promising target. Areas covered: This review outlines the role of GUCY2C in tumorigenesis, and steps to translate GUCY2C-targeting schemes to the clinic. Endogenous GUCY2C-activating ligands disappear early in tumorigenesis, silencing its signaling axis and enabling transformation. Pre-clinical models support GUCY2C ligand supplementation as a novel disease prevention paradigm. With the recent FDA approval of the …

Molecular Staging Of Node Negative Patients With Colorectal Cancer., Terry Hyslop, Scott A Waldman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

Metastatic disease is the principle cause of death from colorectal cancer. In that context, the most significant indicator of overall survival and therapeutic response to adjuvant chemotherapy is the presence of metastatic tumor cells in regional lymph nodes. Although histopathologic analysis of lymph nodes is central to all colorectal cancer staging paradigms, its prognostic and predictive value is limited. Indeed, about 30% of patients with histopathology-negative lymph nodes (pN0) die from metastatic disease, reflected by microscopic lymph node metastases that are overlooked by standard techniques. These unrecognized tumor cells are especially important when considering racial disparities in outcomes in colorectal …

Phosphorylation Of Vasodilator-Stimulated Phosphoprotein Ser239 Suppresses Filopodia And Invadopodia In Colon Cancer., David S Zuzga, Joshua Pelta-Heller, Peng Li, Alessandro Bombonati, Scott A Waldman, Giovanni Mario Pitari

Department of Pharmacology and Experimental Therapeutics Faculty Papers

In colorectal cancer, the antitumorigenic guanylyl cyclase C (GCC) signalome is defective reflecting ligand deprivation from downregulation of endogenous hormone expression. Although the proximal intracellular mediators of that signal transduction system, including cyclic guanosine monophosphate (cGMP) and cGMP-dependent protein kinase (PKG), are well characterized, the functional significance of its distal effectors remain vague. Dysregulation of ligand-dependent GCC signaling through vasodilator-stimulated phosphoprotein (VASP), an actin-binding protein implicated in membrane protrusion dynamics, drastically reduced cGMP-dependent VASP phosphorylation levels in colorectal tumors from patients. Restoration of cGMP-dependent VASP phosphorylation by GCC agonists suppressed the number and length of locomotory (filopodia) and invasive (invadopodia) …

Molecular Staging Individualizing Cancer Management, Alex Mejia, Stephanie Schulz, Terry Hyslop, David S. Weinberg, Scott A. Waldman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

Although the most important prognostic and predictive marker in colorectal cancer is tumor cells in lymph nodes, ∼30% of patients who are node-negative die from occult metastases. Molecular staging employing specific markers and sensitive detection technologies has emerged as a powerful platform to assess prognosis in node-negative colon cancer. Integrating molecular staging into algorithms that individualize patient management will require validation and the definition of relationships between occult tumor cells, prognosis, and responses to chemotherapy. J. Surg. Oncol. 2012; 105:468-474. © 2012 Wiley Periodicals, Inc.

Copyright © 2012 Wiley Periodicals, Inc.

Chronic Diseases: The Emerging Pandemic., Andre Terzic, Scott A. Waldman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

According to the 2011 World Health Organization Global Status Report, of the 57 million annual global deaths – a staggering 36 million or over 63% are due to chronic diseases.¹ Four noncommunicable diseases - namely cardiovascular, cancer, diabetes, and chronic respiratory diseases - emerge as the leading cause of mortality in the world, accounting respectively for 17, 7.6, 4.2, and 1.3 million deaths based on the latest available global epidemiology data. By 2020, global deaths due to chronic diseases are projected to worsen by at least 15 to 20%. It is estimated that the four major noncommunicable diseases will …

Molecular Staging Estimates Occult Tumor Burden In Colorectal Cancer, Alex Mejia, Stephanie Schulz, Terry Hyslop, David S. Weinberg, Scott A. Waldman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

Tumor cells in regional lymph nodes are a key prognostic marker of survival and predictive marker of response to adjuvant chemotherapy in colorectal cancer. However, clinicopathologic techniques to detect lymph node metastases remain imperfect, and ~30% of patients with lymph nodes negative by histology (pN0) develop recurrent disease, reflecting occult metastases that escape detection. These observations underscore an unmet clinical need for accurate approaches to identify occult nodal metastases in colorectal cancer patients. GUCY2C is a receptor whose expression normally is restricted to intestinal epithelial cells, but is universally over-expressed by colorectal cancer cells. A prospective, multicenter, blinded clinical trial …

Enterotoxin Preconditioning Restores Calcium-Sensing Receptor-Mediated Cytostasis In Colon Cancer Cells, Giovanni Mario Pitari, Jieru E. Lin, Fawad J. Shah, Wilhelm J. Lubbe, David Zuzga, Peng Li, Stephanie Schulz, Scott A Waldman

Department of Pharmacology and Experimental Therapeutics Faculty Papers

Guanylyl cyclase C (GCC), the receptor for diarrheagenic bacterial heat-stable enterotoxins (STs), inhibits colorectal cancer cell proliferation by co-opting Ca(2+) as the intracellular messenger. Similarly, extracellular Ca(2+) (Ca(2+)(o)) opposes proliferation and induces terminal differentiation in intestinal epithelial cells. In that context, human colon cancer cells develop a phenotype characterized by insensitivity to cytostasis imposed by Ca(2+)(o). Here, preconditioning with ST, mediated by GCC signaling through cyclic nucleotide-gated channels, restored Ca(2+)(o)-dependent cytostasis, reflecting posttranscriptional regulation of calcium-sensing receptors (CaRs). ST-induced GCC signaling deployed CaRs to the surface of human colon cancer cells, whereas elimination of GCC signaling in mice nearly abolished …