Effects of 5‑fluorouracil and class III phosphoinositide 3‑kinase small interfering RNA combination therapy on SGC7901 human gastric cancer cells

Molecular pathogenesis and emerging targets of gastric adenocarcinoma

Gastric adenocarcinoma (GC) is a devastating disease and is the third leading cause of cancer deaths worldwide. This heterogeneous disease has several different classification systems that consider histological appearance and genomic alterations. Understanding the etiology of GC, including infection, hereditary conditions, and environmental factors, is of particular importance and is discussed in this review. To improve survival in GC, we also must improve our therapeutic strategies. Here, we discuss new targets that warrant further exploration.

Autophagy-targeted therapy to modulate age-related diseases: Success, pitfalls, and new directions

Autophagy is a critical metabolic process that supports homeostasis at a basal level and is dynamically regulated in response to various physiological and pathological processes. Autophagy has some etiologic implications that support certain pathological processes due to alterations in the lysosomal-degradative pathway. Some of the conditions related to autophagy play key roles in highly relevant human diseases, e.g., cardiovascular diseases (15.5%), malignant and other neoplasms (9.4%), and neurodegenerative conditions (3.7%). Despite advances in the discovery of new strategies to treat these age-related diseases, autophagy has emerged as a therapeutic option after preclinical and clinical studies. Here, we discuss the pitfalls and success in regulating autophagy initiation and its lysosome-dependent pathway to restore its homeostatic role and mediate therapeutic effects for cancer, neurodegenerative, and cardiac diseases. The main challenge for the development of autophagy regulators for clinical application is the lack of specificity of the repurposed drugs, due to the low pharmacological uniqueness of their target, including those that target the PI3K/AKT/mTOR and AMPK pathway. Then, future efforts must be conducted to deal with this scenery, including the disclosure of key components in the autophagy machinery that may intervene in its therapeutic regulation. Among all efforts, those focusing on the development of novel allosteric inhibitors against autophagy inducers, as well as those targeting autolysosomal function, and their integration into therapeutic regimens should remain a priority for the field.

Functional role of autophagy in gastric cancer

Autophagy is a highly regulated catabolic pathway responsible for the degradation of long-lived proteins and damaged intracellular organelles. Perturbations in autophagy are found in gastric cancer. In host gastric cells, autophagy can be induced by Helicobacter pylori (or H. pylori) infection, which is associated with the oncogenesis of gastric cancer. In gastric cancer cells, autophagy has both pro-survival and pro-death functions in determining cell fate. Besides, autophagy modulates gastric cancer metastasis by affecting a wide range of pathological events, including extracellular matrix (ECM) degradation, epithelial-to-mesenchymal transition (EMT), tumor angiogenesis, and tumor microenvironment. In addition, some of the autophagy-related proteins, such as Beclin 1, microtubule-associated protein 1 light chain 3 (MAP1-LC3), and p62/sequestosome 1 (SQSTM1) have certain prognostic values for gastric cancer. In this article, we review the recent studies regarding the functional role of autophagy in gastric cancer.

Autophagy in 5-Fluorouracil Therapy in Gastrointestinal Cancer: Trends and Challenges

Objective:

5-Fluorouracil (5-FU)-based combination therapies are standard treatments for gastrointestinal cancer, where the modulation of autophagy is becoming increasingly important in offering effective treatment for patients in clinical practice. This review focuses on the role of autophagy in 5-FU-induced tumor suppression and cancer therapy in the digestive system.

Data Sources:

All articles published in English from 1996 to date those assess the synergistic effect of autophagy and 5-FU in gastrointestinal cancer therapy were identified through a systematic online search by use of PubMed. The search terms were “autophagy” and “5-FU” and (“colorectal cancer” or “hepatocellular carcinoma” or “pancreatic adenocarcinoma” or “esophageal cancer” or “gallbladder carcinoma” or “gastric cancer”).

Study Selection:

Critical reviews on relevant aspects and original articles reporting in vitro and/or in vivo results regarding the efficiency of autophagy and 5-FU in gastrointestinal cancer therapy were reviewed, analyzed, and summarized. The exclusion criteria for the articles were as follows: (1) new materials (e.g., nanomaterial)-induced autophagy; (2) clinical and experimental studies on diagnostic and/or prognostic biomarkers in digestive system cancers; and (3) immunogenic cell death for anticancer chemotherapy.

Results:

Most cell and animal experiments showed inhibition of autophagy by either pharmacological approaches or via genetic silencing of autophagy regulatory gene, resulting in a promotion of 5-FU-induced cancer cells death. Meanwhile, autophagy also plays a pro-death role and may mediate cell death in certain cancer cells where apoptosis is defective or difficult to induce. The dual role of autophagy complicates the use of autophagy inhibitor or inducer in cancer chemotherapy and generates inconsistency to an extent in clinic trials.

Conclusion:

Autophagy might be a therapeutic target that sensitizes the 5-FU treatment in gastrointestinal cancer.

Autophagy regulation and its role in gastric cancer and colorectal cancer

BACKGROUND

Autophagy is associated with the occurrence, development, cellular adaptation, progression, treatment and prognosis of gastric cancer (GC) and colorectal cancer (CRC). The effect of autophagy in these two cancers has attracted our attention.

OBJECTIVE

The aim of this study was to describe the functional and regulatory mechanisms associated with autophagy in GC and CRC.

METHODS

We reviewed recent publications describing the role of autophagy in GC and CRC, including the functional characteristics, clinical significance and regulatory mechanisms.

RESULTS

Autophagy plays context-dependent dual roles in the development and progression of GC and CRC. It can either promote tumor growth and cell survival or can contribute to tumor suppression and promote cell death. Both of these effects employ complex regulatory networks, such as those mediated by p53, PI3K/Akt/mTOR, Ras and microRNA. Among the cellular process associated with these pathways, autophagy is a potential target for anti-tumor therapy.

CONCLUSION

Autophagy is associated with both tumorigenic and protective effects in cancer. However, the role of autophagy in GC and CRC remains unclear. Although the translation of the basic science of autophagy into clinical practice is a long process, the modulation of autophagy as a potential therapeutic approach in GC and CRC merits further investigation.