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Autophagy is a process of degradation and catabolism in cells. By removing damaged or dysfunctional organelles, autophagy interacts with the ubiquitin‑proteasome degradation system to jointly regulate cell function and energy homeostasis. Since autophagy plays a key role in physiology, disorders of the autophagy mechanism are associated with various diseases. Therefore, thorough understanding of the autophagy regulatory mechanism are crucially important in the diagnosis and treatment of diseases. To date, ion channels may affect the development and treatment of diseases by regulating autophagy, especially calcium‑permeable ion channels, in the process of digestive system diseases. However, the mechanism by which calcium ions and their channels regulate autophagy is still poorly understood, thus emphasizing the need for further research in this field. The present review intends to discuss the association, mechanism and application of calcium ions, their channels and autophagy in the occurrence and development of digestive system diseases.

The upper gastrointestinal (GI) tumors are multifactorial diseases associated with a combination of oncogenes and environmental factors. Currently, surgery, chemotherapy, radiotherapy and immunotherapy are relatively effective treatment options for the patients with these tumors. However, the asymptomatic phenotype of these tumors during the early stages poses as a significant limiting factor to diagnosis and often renders treatments ineffective. Therefore, new early diagnosis and effective therapy for upper GI tumors are urgently needed. Ca 2+ is a pivotal intracellular second messenger and plays a crucial role in living cells by regulating several processes from cell division to death. The aberrant Ca 2+ homeostasis is related to many human pathological conditions and diseases, including cancer, and thus the changes in the expression and function of plasma membrane Ca 2+ permeable channels and sodium/calcium exchangers are frequently described in tumorigenesis and tumor development of the upper GI tract, including voltage-gated Ca 2+ channels (VGCC), transient receptor potential (TRP) channels, store-operated channels (SOC) and Na + /Ca 2+ exchanger (NCX). This review will summarize the current knowledge about plasma membrane Ca 2+ permeable channels and sodium/calcium exchangers in the upper GI tumors and provide a synopsis of recent advancements on the role and involvement of these channels in upper GI tumors as well as a discussion of the possible strategies to target these channels and exchangers for diagnosis and therapy of the upper GI tumors., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

Intracellular calcium (Ca2+) is a critical cell signaling component in gastrointestinal (GI) physiology. Cytosolic calcium ([Ca2+]cyt), as a secondary messenger, controls GI epithelial fluid and ion transport, mucus and neuropeptide secretion, as well as synaptic transmission and motility. The key roles of Ca2+ signaling in other types of secretory cell (including those in the airways and salivary glands) are well known. However, its action in GI epithelial secretion and the underlying molecular mechanisms have remained to be fully elucidated. The present review focused on the role of [Ca2+]cyt in GI epithelial anion secretion. Ca2+ signaling regulates the activities of ion channels and transporters involved in GI epithelial ion and fluid transport, including Cl- channels, Ca2+-activated K+ channels, cystic fibrosis (CF) transmembrane conductance regulator and anion/HCO3- exchangers. Previous studies by the current researchers have focused on this field over several years, providing solid evidence that Ca2+ signaling has an important role in the regulation of GI epithelial anion secretion and uncovering underlying molecular mechanisms. The present review is largely based on previous studies by the current researchers and provides an overview of the currently known molecular mechanisms of GI epithelial anion secretion with an emphasis on Ca2+-mediated ion secretion and its dysregulation in GI disorders. In addition, previous studies by the current researchers demonstrated that different regulatory mechanisms are in place for GI epithelial HCO3- and Cl- secretion. An increased understanding of the roles of Ca2+ signaling and its targets in GI anion secretion may lead to the development of novel strategies to inhibit GI diseases, including the enhancement of fluid secretion in CF and protection of the GI mucosa in ulcer diseases. [ABSTRACT FROM AUTHOR]

Cytosolic calcium [Ca2+] cyt signaling plays a critical role in the regulation of multiple cellular functions, and Ca2+ channels/transporters are important to regulate calcium homeostasis whose abnormality may contribute human tumorogenesis including colorectal cancer (CRC). In this review, we summarized and discussed the current knowledge on pathogenic roles of the altered [Ca2+] cyt and Ca2+ channels/transporters like SOCE, TRP channels, SERCA and Na+/Ca2+ exchangers in CRC tumorigenesis and progression. Understanding the detailed molecular mechanisms underlying the effects of [Ca2+] cyt on CRC is essential to develop Ca2+ channels/transporters as diagnostic and therapeutic targets. Targeting Ca2+ signaling for cancer therapy has become an emerging research area nowadays, although our knowledge about the roles of Ca2+ channels/transporters in tumorigenesis is still in the early stage, we still believe that they will act as novel preventive/therapeutic targets for CRC with potentially extensive clinical significance. [ABSTRACT FROM AUTHOR]