Examining linaclotide for the treatment of chronic idiopathic constipation.

INTRODUCTION: Chronic idiopathic constipation (CIC) is characterized by infrequent bowel movements and hard stools lasting for at least three months or longer. This disease affects 8-12% of the US population and 10-17% of the world population. Treatment and management involve identifying the primary cause, changing dietary habits, and adequate physical activity. Linaclotide is a guanylate cyclase-agonist acting locally in the luminal surface of the intestinal enterocyte leading to a signal transduction cascade, activation of the cystic fibrosis transmembrane conductance regulator (CFTR), thus increasing secretion of chloride and bicarbonate into the intestinal lumen with eventual increased intestinal fluid and faster transit time. AREAS COVERED: We reviewed multiple studies and did a thorough literature review on CIC including its pathophysiology. Through this literature review we were able to discuss and give the context and rationale for drug regimens indicated for CIC. EXPERT OPINION: The era we live in right now is akin to nutrient-rich and fertilized soil as knowledge and resources are abundant. The opportunities and potential are endless. Constipation being more extensively studied, our understanding of medications and diseases broadens, leading to novel medications being discovered. Linaclotide is a pioneer in this aspect and can pave the way for future generations.

Current and future pharmacotherapies for the management of constipation-predominant irritable bowel syndrome.

INTRODUCTION: Irritable bowel syndrome (IBS) is a common gastrointestinal disorder affecting 9-23% of the world's population, with a higher prevalence among women. IBS is a complex disorder influenced by psychosocial, physiological, and genetic factors, exacerbated by stress. AREAS COVERED: Research confirms that the most common subtype of IBS is IBS-C. Therefore, new therapies are being developed to speed up bowel movement and reduce constipation, with drugs such as linaclotide, plecanatide, lubiprostone, or tegaserod available to reduce IBS-C symptoms. In addition, patients' condition is improved by foods rich in fiber and low in FODMAP and the use of biotics. EXPERT OPINION: The topic is of great importance due to the growing number of patients suffering from IBS-C and its significant impact on quality of life. Current clinical trials of new therapeutic options are not too successful, and it seems that one of the plausible treatment options could be the multi-drug cocktail with some, or perhaps even all its ingredients emerging from drug re-purposing. Another important path that needs to be explored further in IBS-C patients is the adjustment of dietary habits and/or introduction of dietary or nutritional intervention.

The gut microbiota participates in the effect of linaclotide in patients with irritable bowel syndrome with constipation (IBS-C): a multicenter, prospective, pre-post study.

BACKGROUND: Interindividual variation characterizes the relief experienced by constipation-predominant irritable bowel syndrome (IBS-C) patients following linaclotide treatment. Complex bidirectional interactions occur between the gut microbiota and various clinical drugs. To date, no established evidence has elucidated the interactions between the gut microbiota and linaclotide. We aimed to explore the impact of linaclotide on the gut microbiota and identify critical bacterial genera that might participate in linaclotide efficacy. METHODS: IBS-C patients were administered a daily linaclotide dose of 290 µg over six weeks, and their symptoms were then recorded during a four-week posttreatment observational period. Pre- and posttreatment fecal samples were collected for 16S rRNA sequencing to assess alterations in the gut microbiota composition. Additionally, targeted metabolomics analysis was performed for the measurement of short-chain fatty acid (SCFA) concentrations. RESULTS: Approximately 43.3% of patients met the FDA responder endpoint after taking linaclotide for 6 weeks, and 85% of patients reported some relief from abdominal pain and constipation. Linaclotide considerably modified the gut microbiome and SCFA metabolism. Notably, the higher efficacy of linaclotide was associated with enrichment of the Blautia genus, and the abundance of Blautia after linaclotide treatment was higher than that in healthy volunteers. Intriguingly, a positive correlation was found for the Blautia abundance and SCFA concentrations with improvements in clinical symptoms among IBS-C patients. CONCLUSION: The gut microbiota, especially the genus Blautia, may serve as a significant predictive microbe for symptom relief in IBS-C patients receiving linaclotide treatment. TRIAL REGISTRATION: This trial was registered with the Chinese Clinical Trial Registry (Chictr.org.cn, ChiCTR1900027934).

Comparative profiles of lubiprostone, linaclotide, and elobixibat for chronic constipation: a systematic literature review with meta-analysis and number needed to treat/harm.

OBJECTIVE: To comprehensively evaluate the efficacy, safety, patient symptoms, and quality-of-life (QoL) of lubiprostone, linaclotide, and elobixibat as treatment for chronic constipation (CC). DESIGN: Systematic literature review (SLR) and meta-analysis (MA). Literature searches were conducted on PubMed and Embase using the Ovid platform. METHODS: SLR including randomized controlled trials (RCTs) and observational studies was conducted to identify the overall efficacy and safety of lubiprostone, linaclotide, and elobixibat. Thereafter, MA was performed using only RCTs. The number needed to treat (NNT) and number needed to harm (NNH) analyses were additionally conducted. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome was efficacy regarding change in spontaneous bowel movements. Secondary outcomes included safety, constipation-related symptoms, and QoL. RESULTS: Twenty-four studies met the inclusion criteria for the SLR: 17 RCTs, 4 observational studies, and 3 single-arm trials. Feasibility assessment for the MA resulted in 14 studies available for safety data analysis, and 8 available for efficacy analysis, respectively. Three drugs showed similar efficacy in the MA and NNT analysis. However, the NNH analysis revealed distinct safety profiles: lubiprostone, linaclotide, and elobixibat were linked to the highest risk of nausea, diarrhea, and abdominal pain, respectively. CONCLUSION: The current study provides an updated overview of the efficacy, safety, patient symptoms, and QoL of the three drugs with different mechanisms of action for CC treatment.The findings could help physicians adopt an individualized approach for treating patients with CC in clinical practice.

The evolutionary divergence of receptor guanylyl cyclase C has implications for preclinical models for receptor-directed therapeutics.

Mutations in receptor guanylyl cyclase C (GC-C) cause severe gastrointestinal disease, including meconium ileus, early onset acute diarrhea, and pediatric inflammatory bowel disease that continues into adulthood. Agonists of GC-C are US Food and Drug Administration-approved drugs for the treatment of constipation and irritable bowel syndrome. Therapeutic strategies targeting GC-C are tested in preclinical mouse models, assuming that murine GC-C mimics human GC-C in its biochemical properties and downstream signaling events. Here, we reveal important differences in ligand-binding affinity and GC activity between mouse GC-C and human GC-C. We generated a series of chimeric constructs of various domains of human and mouse GC-C to show that the extracellular domain of mouse GC-C contributed to log-orders lower affinity of mouse GC-C for ligands than human GC-C. Further, the Vmax of the murine GC domain was lower than that of human GC-C, and allosteric regulation of the receptor by ATP binding to the intracellular kinase-homology domain also differed. These altered properties are reflected in the high concentrations of ligands required to elicit signaling responses in the mouse gut in preclinical models and the specificity of a GC inhibitor towards human GC-C. Therefore, our studies identify considerations in using the murine model to test molecules for therapeutic purposes that work as either agonists or antagonists of GC-C, and vaccines for the bacterial heat-stable enterotoxin that causes watery diarrhea in humans.

Enteroendocrine cell regulation of the gut-brain axis.

Enteroendocrine cells (EECs) are an essential interface between the gut and brain that communicate signals about nutrients, pain, and even information from our microbiome. EECs are hormone-producing cells expressed throughout the gastrointestinal epithelium and have been leveraged by pharmaceuticals like semaglutide (Ozempic, Wegovy), terzepatide (Mounjaro), and retatrutide (Phase 2) for diabetes and weight control, and linaclotide (Linzess) to treat irritable bowel syndrome (IBS) and visceral pain. This review focuses on role of intestinal EECs to communicate signals from the gut lumen to the brain. Canonically, EECs communicate information about the intestinal environment through a variety of hormones, dividing EECs into separate classes based on the hormone each cell type secretes. Recent studies have revealed more diverse hormone profiles and communication modalities for EECs including direct synaptic communication with peripheral neurons. EECs known as neuropod cells rapidly relay signals from gut to brain via a direct communication with vagal and primary sensory neurons. Further, this review discusses the complex information processing machinery within EECs, including receptors that transduce intraluminal signals and the ion channel complement that govern initiation and propagation of these signals. Deeper understanding of EEC physiology is necessary to safely treat devastating and pervasive conditions like irritable bowel syndrome and obesity.

Management of Chronic Constipation: A Comprehensive Review.

Traditionally, the treatment of chronic constipation has focused on lifestyle modification, dietary guidance and therapy, and osmotic and stimulant laxatives. Recently, several drugs with new mechanisms of action have been introduced as treatments for chronic constipation. In Japan, polyethylene glycol and lactulose can now be administered under insurance coverage. The number of treatment options for constipation has increased dramatically. First, lifestyle modifications and dietary therapies must be implemented. If constipation does not improve sufficiently, specialized functional tests are performed to diagnose physiological subgroups. If functional tests are not available, patients are classified as having the "decreased frequency of defecation" type or the "difficult defecation" type based on the patient's symptoms, with treatment applied according to each type. Medical therapy includes osmotic laxatives, secretagogues, bile acid transporter inhibitors, probiotics, prokinetics, and Kampo medicines. The temporary use of stimulant laxatives, suppositories, enemas, and digital evacuation is also recommended. The usefulness of biofeedback is yet to be determined.

Microbiota-derived butyrate dampens linaclotide stimulation of the guanylate cyclase C pathway in patient-derived colonoids.

BACKGROUND & AIMS: Disorders of gut-brain interaction (DGBI) are complex conditions that result in decreased quality of life and a significant cost burden. Linaclotide, a guanylin cyclase C (GCC) receptor agonist, is approved as a DGBI treatment. However, its efficacy has been limited and variable across DGBI patients. Microbiota and metabolomic alterations are noted in DGBI patients, provoking the hypothesis that the microbiota may impact the GCC response to current therapeutics. METHODS: Human-derived intestinal organoids were grown from pediatric DGBI, non-IBD colon biopsies (colonoids). Colonoids were treated with 250 nM linaclotide and assayed for cGMP to develop a model of GCC activity. Butyrate was administered to human colonoids overnight at a concentration of 1 mM. Colonoid lysates were analyzed for cGMP levels by ELISA. For the swelling assay, colonoids were photographed pre- and post-treatment and volume was measured using ImageJ. Principal coordinate analyses (PCoA) were performed on the Bray-Curtis dissimilarity and Jaccard distance to assess differences in the community composition of short-chain fatty acid (SCFA) producing microbial species in the intestinal microbiota from pediatric patients with IBS and healthy control samples. KEY RESULTS: Linaclotide treatment induced a significant increase in [cGMP] and swelling of patient-derived colonoids, demonstrating a human in vitro model of linaclotide-induced GCC activation. Shotgun sequencing analysis of pediatric IBS patients and healthy controls showed differences in the composition of commensal SCFA-producing bacteria. Butyrate exposure significantly dampened linaclotide-induced cGMP levels and swelling in patient-derived colonoids. CONCLUSIONS & INFERENCES: Patient-derived colonoids demonstrate that microbiota-derived butyrate can dampen human colonic responses to linaclotide. This study supports incorporation of microbiota and metabolomic assessment to improve precision medicine for DGBI patients.

Bowel preparation efficacy and safety of compound polyethylene glycol electrolyte powder combined with linaclotide for colonoscopy: A randomized controlled trial.

Background and Aim: Adequate bowel preparation is essential for colonoscopy, which is important for detecting colon polyps and preventing colorectal cancer. Linaclotide is approved for irritable bowel syndrome with predominant constipation (IBS-C) symptoms. The main objective of this study was to explore the quality of bowel preparation by low-volume compound polyethylene glycol (PEG) combined with linaclotide. Methods: A total of 266 patients who underwent colonoscopy in Shangrao People's Hospital from June 2021 to June 2022 were randomized to 1 of 3 split PEG regimens: 4LPEG, 2LPEG, and 2LPEG + L (linaclotide). The primary end point was adequate bowel preparation (Boston Bowel Preparation Scale [BBPS] total score of ≥6, with each of three colonic segments subscores ≥2). Secondary outcomes were polyp detection rates and the incidence of adverse reactions. Results: Over 12 months, 266 subjects were randomized into 2LPEG (n = 12), 4LPEG (n = 112), or 2LPEG + L (n = 142). There were no significant differences between the 4LPEG and 2LPEG + L groups in achieving adequate bowel preparation (P > 0.05). The mean BBPS score of the total colon, left hemi-colon, right hemi-colon, and transverse in the 2LPEG + L group was higher than that in the 2LPEG group (P < 0.001). Patient's sleeping quality and the incidence of adverse reactions of 2LPEG + L group were compatible with 2LPEG group, but it was significantly lower than that in 4LPEG group. There was no statistically significant difference in the detection rate of colon polyps between each group. Conclusion: The quality of bowel preparation of the compound polyethylene glycol electrolyte powder combined with linaclotide is approximately the same as that of 4LPEG, and it can reduce the adverse reactions in the process of bowel preparation, and its intestinal cleansing effect is also better than that of 2LPEG.

American Gastroenterological Association-American College of Gastroenterology Clinical Practice Guideline: Pharmacological Management of Chronic Idiopathic Constipation.

INTRODUCTION: Chronic idiopathic constipation (CIC) is a common disorder associated with significant impairment in quality of life. This clinical practice guideline, jointly developed by the American Gastroenterological Association and the American College of Gastroenterology, aims to inform clinicians and patients by providing evidence-based practice recommendations for the pharmacological treatment of CIC in adults. METHODS: The American Gastroenterological Association and the American College of Gastroenterology formed a multidisciplinary guideline panel that conducted systematic reviews of the following agents: fiber, osmotic laxatives (polyethylene glycol, magnesium oxide, lactulose), stimulant laxatives (bisacodyl, sodium picosulfate, senna), secretagogues (lubiprostone, linaclotide, plecanatide), and serotonin type 4 agonist (prucalopride). The panel prioritized clinical questions and outcomes and used the Grading of Recommendations Assessment, Development, and Evaluation framework to assess the certainty of evidence for each intervention. The Evidence to Decision framework was used to develop clinical recommendations based on the balance between the desirable and undesirable effects, patient values, costs, and health equity considerations. RESULTS: The panel agreed on 10 recommendations for the pharmacological management of CIC in adults. Based on available evidence, the panel made strong recommendations for the use of polyethylene glycol, sodium picosulfate, linaclotide, plecanatide, and prucalopride for CIC in adults. Conditional recommendations were made for the use of fiber, lactulose, senna, magnesium oxide, and lubiprostone. DISCUSSION: This document provides a comprehensive outline of the various over-the-counter and prescription pharmacological agents available for the treatment of CIC. The guidelines are meant to provide a framework for approaching the management of CIC; clinical providers should engage in shared decision making based on patient preferences as well as medication cost and availability. Limitations and gaps in the evidence are highlighted to help guide future research opportunities and enhance the care of patients with chronic constipation.

A New Regioselective Synthesis of the Cysteine-Rich Peptide Linaclotide.

Linaclotide is a 14-amino acid residue peptide approved by the FDA for the treatment of irritable bowel syndrome with constipation (IBS-C), which activates guanylate cyclase C to accelerate intestinal transit. Here we show a new method for the synthesis of linaclotide through the completely selective formation of three disulfide bonds in satisfactory overall yields via mild oxidation reactions of the solid phase and liquid phase, using 4-methoxytrityl (Mmt), diphenylmethyl (Dpm) and 2-nitrobenzyl (O-NBn) protecting groups of cysteine as substrate, respectively.

An update on the use of pharmacotherapy for opioid-induced bowel dysfunction.

INTRODUCTION: With the growing rate of aging and the incidence of chronic diseases, there has been an upsurge in opioid prescription and abuse worldwide. This has been associated with increased reports of opioid-related adverse events, particularly opioid-induced bowel dysfunction (OIBD), calling for a rational clinical management strategy. AREAS COVERED: Through searching PubMed, Scopus, Cochrane Library, and Web of Science, English literature was gathered as of 1 January 2017. Furthermore, the USFDA, EMA, TGA, Clinicaltrials.Gov, WHO-ICTRP databases, and the latest guidelines were reviewed to extract ongoing clinical studies and provide an evidence-based expert opinion with detailed information on efficacy, safety, approval status, and pharmacokinetics of the currently used medications. EXPERT OPINION: Despite the significant burden of OIBD, the clinical development of agents lags behind disease progress. Although in most places, management of opioid-induced constipation (OIC) is initiated by lifestyle modifications followed by laxatives, opioid antagonists, and secretagogue agents, there are still major conflicts among global guidelines. The fundamental reason is the lack of head-to-head clinical trials providing inter- and intragroup comparisons between PAMORAs, laxatives, and secretagogue agents. These investigations must be accompanied by further valid biopharmaceutical and economic evaluations, paving the way for rational clinical judgment in each context.

A clinical study of linaclotide combined with compound polyethylene glycol electrolytes powder for bowel preparation for colonoscopy / 中华消化内镜杂志

Objective:To explore the value of linaclotide combined with compound polyethylene glycol electrolytes powder (PEG) for bowel preparation for colonoscopy.Methods:A randomized and single blind prospective clinical study was conducted in patients who intended to receive colonoscopy at the Department of Gastroenterology in Shenzhen Hospital, Southern Medical University from June 2021 to August 2021. One hundred and fifty-two patients in the experimental group were treated with 580 μg linaclotide + 2 L PEG, and 152 patients in the control group were treated with 3 L PEG. The bowel preparation effects including Boston bowel preparation scale (BBPS) score, bubble score and lesion detection rate, and safety (adverse events) were compared between the two groups.Results:The total BBPS scores were 9 (8, 9) in the experimental group, and 9 (9, 9) in the control group with no significant difference ( Z=0.141, P=0.888). The bubble scores were 1 (1, 2) in the experimental group, and 1 (1, 1) in the control group with no significant difference ( Z=1.788, P=0.074). There was no significant difference in detection rate of lesions between the experimental group and the control group [37.50% (57/152) VS 33.55% (51/152), χ2=0.517, P=0.472]. There was no significant difference in safety including incidence of nausea [7.24% (11/152) VS 13.16% (20/152), χ2=2.910, P=0.088], vomiting [2.63% (4/152) VS 7.24% (11/152), χ2=3.436, P=0.064], abdominal distension [7.89% (12/152) VS 11.84% (18/152), χ2=1.331, P=0.249] and abdominal pain [2.63% (4/152) VS 4.61% (7/152), χ2=0.849, P=0.357] between the experimental group and the control group. Conclusion:Linaclotide combined with PEG for colonoscopic bowel preparation reduces drinking water volume. The cleaning effect and safety are comparable to using 3 L PEG. It can be recommended for bowel preparation for colonoscopy.

Rapid health technology assessment of linaclotide in the treatment of constipated irritable bowel syndrome / 中国药房

OBJECTIVE To comprehensively evaluate the effectiveness， safety and economics of linaclotide in the treatment of constipated irritable bowel syndrome （IBS-C）， and to provide the evidence-based basis for clinical application. METHODS Rapid health technology assessment method was adopted； PubMed， Embase， the Cochrane Library， Web of Science， CNKI， Wanfang data， VIP database， SinoMed， and related HTA websites were searched. Systematic review/meta-analysis， HTA reports and pharmacoeconomic research about linaclotide were collected. After literature screening， data extraction and quality evaluation， descriptive analysis was used to classify and summarize the research results. RESULTS A total of 11 literature were included， involving 7 systematic reviews/meta-analyses and 4 pharmacoeconomic research. In terms of effectiveness， compared with placebo， linaclotide could achieve FDA specified endpoint and European Medicines Agency-recommended endpoint faster， significantly improved patients’ complete spontaneous bowel movements （CSBM）， abdominal pain， constipation and quality of life， and relieved patients’ global symptoms； compared with the indirect evidence of lubiprostone， plecanatide and tenapanor， the efficacy of linaclotide at the FDA specified endpoint， CSBM， abdominal pain relief， and global relief response were the best. In terms of safety， the incidence of overall adverse drug reactions， diarrhea and flatulence caused by linaclotide were significantly higher than placebo，but patients can tolerate them. In terms of economics， compared with traditional therapeutic drugs， linaclotide showed an economic advantage. CONCLUSIONS Linaclotide has advantages in efficacy， safety and economics in the treatment of IBS-C. It is an effective strategy for the treatment of IBS-C.

Efficacy of Compound Polyethylene Glycol Electrolyte Powder Combined With Linaclotide in Bowel Preparation: A Clinical Randomized Controlled Study / 胃肠病学

Background: The traditional bowel preparation compound polyethylene glycol electrolyte powder (PEG) has poor tolerance in some patients due to the need for a large amount of water, which has a limited cleaning effect and affects the visual field of observation. Therefore, it is of clinical significance to find a bowel cleaning method with strong cleaning power, high safety and is acceptable to most of the patients. Aims: To explore the efficacy and safety of PEG combined with linaclotide in bowel preparation. Methods: A total of 414 patients were randomly divided into 3 groups: control group (3 L PEG group), observation group A (3 L PEG+290 μg linaclotide), observation group B (2 L PEG+290 μg linaclotide). The primary outcome was the efficacy of bowel preparation based on the Boston bowel preparation scale (BBPS), the secondary outcomes were withdrawal time, time interval from preparation to colonoscopy, incidence of complications, cecal insertion rate, detection rates of polyps, adenoma, hemorrhoid and other diseases. BBPS score in constipation subgroup was analyzed. Results: The appropriate bowel preparation rate, BBPS score, and detection rates of polyps and hemorrhoid in observation group A were significantly higher than those in control group and observation group B (P0.05). There were no significant differences in cecal insertion rate, incomplete colonoscopy rate, detection rates of adenoma and other diseases, withdrawal time, time interval from preparation to colonoscopy, and incidence of adverse reactions among the three groups (P>0.05). BBPS score in constipation patients in observation group A was significantly higher than that in observation group B and control group (P<0.05). Conclusions: Linaclotide is safe and effective as an adjuvant for bowel preparation. 3 L PEG combined with linaclotide can improve the quality of bowel cleaning.

Exploratory, multicenter, open-label study to evaluate the effects of linaclotide in patients with chronic constipation with an insufficient response to magnesium oxide: A study protocol.

Background: Chronic constipation leads to poor quality of life, and treatment remains unsatisfactory for patients. In Japan, magnesium oxide has been commonly used as the first choice of treatment for constipation; however, there are some cases of low satisfaction with magnesium oxide treatment. Linaclotide has recently been used to treat chronic constipation. In this study, we will examine whether linaclotide improves symptoms and quality of life in patients showing insufficient response to magnesium oxide. Methods: This is an exploratory multicenter open-label study. The target number of patients is 64: 32 patients with and 32 without abdominal symptoms. Patients with chronic idiopathic constipation or irritate bowel syndrome with constipation diagnosed according to the Rome-IV criteria are eligible. Patients prescribed 0.99-2 g/day of magnesium oxide for at least 4 weeks will be included. Those who consent to the study will continue taking magnesium oxide for 2-4 weeks, and defecation will be documented. Patients who meet the criteria will be prescribed linaclotide (0.5 mg) daily for 12 weeks. The primary endpoint is a change in the Japanese version of the Patient Assessment of Constipation Quality of Life (JPAC-QOL) score after 12 weeks of treatment. Conclusion: This is the first study to investigate the usefulness of linaclotide as a second-line treatment for chronic constipation. We will test the efficacy of treatment of constipation in patients with inadequate response to magnesium oxide. Trial registration: This study is registered with the Japan Registry of Clinical Trials (jRCT, jRCTs031200048).

Guanylyl cyclase C as a diagnostic and therapeutic target in colorectal cancer.

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 this context, GUCY2C satisfies many characteristics of a compelling target and biomarker for gastrointestinal malignancies.

Colorectal cancer is a leading cause of death in the USA. In recent years, there has been a shift in the field of oncology from generic treatments, such as surgery and chemotherapy, to personalized molecular therapies, which focus on targeting specific attributes of each patient's unique cancer. Guanylyl cyclase C is a receptor expressed in the intestinal tract, where it regulates fluid secretion and prevents tumor formation. Beyond its function in the healthy intestine, it is expressed in colorectal tumors, and other types of cancer, where it regulates transformation. Therefore, guanylyl cyclase C can serve as a useful target in cancer for prevention and therapy, as well as a marker for tumor cell detection.