Role of TXNDC5 in tumorigenesis of colorectal cancer cells: In vivo and in vitro evidence

Thioredoxin Domain Containing 5 (TXNDC5): Friend or Foe?

This review focuses on the thioredoxin domain containing 5 (TXNDC5), also known as endoplasmic reticulum protein 46 (ERp46), a member of the protein disulfide isomerase (PDI) family with a dual role in multiple diseases. TXNDC5 is highly expressed in endothelial cells, fibroblasts, pancreatic β-cells, liver cells, and hypoxic tissues, such as cancer endothelial cells and atherosclerotic plaques. TXNDC5 plays a crucial role in regulating cell proliferation, apoptosis, migration, and antioxidative stress. Its potential significance in cancer warrants further investigation, given the altered and highly adaptable metabolism of tumor cells. It has been reported that both high and low levels of TXNDC5 expression are associated with multiple diseases, such as arthritis, cancer, diabetes, brain diseases, and infections, as well as worse prognoses. TXNDC5 has been attributed to both oncogenic and tumor-suppressive features. It has been concluded that in cancer, TXNDC5 acts as a foe and responds to metabolic and cellular stress signals to promote the survival of tumor cells against apoptosis. Conversely, in normal cells, TXNDC5 acts as a friend to safeguard cells against oxidative and endoplasmic reticulum stress. Therefore, TXNDC5 could serve as a viable biomarker or even a potential pharmacological target.

The role and mechanism of TXNDC5 in diseases

Thioredoxin domain-containing protein 5 (TXNDC5) is a member of the protein disulfide isomerase (PDI) family. It can promote the formation and rearrangement of disulfide bonds, ensuring proper protein folding. TXNDC5 has three Trx-like domains, which can act independently to introduce disulfide bonds rapidly and disorderly. TXNDC5 is abnormally expressed in various diseases, such as cancer, rheumatoid arthritis (RA), etc. It can protect cells from oxidative stress, promote cell proliferation, inhibit apoptosis and promote the progression of disease. Aberrant expression of TXNDC5 in different diseases suggests its role in disease diagnosis. In addition, targeting TXNDC5 in the treatment of diseases has shown promising application prospects. This article reviews the structure and function of TXNDC5 as well as its role and mechanism in cancer, RA and other diseases.

Thioredoxin Domain Containing 5 Suppression Elicits Serum Amyloid A-Containing High-Density Lipoproteins

Thioredoxin domain containing 5 (TXNDC5) is a protein disulfide isomerase involved in several diseases related to oxidative stress, energy metabolism and cellular inflammation. In a previous manuscript, a negative association between fatty liver development and hepatic Txndc5 expression was observed. To study the role of TXNDC5 in the liver, we generated Txndc5-deficient mice. The absence of the protein caused an increased metabolic need to gain weight along with a bigger and fatter liver. RNAseq was performed to elucidate the putative mechanisms, showing a substantial liver overexpression of serum amyloid genes (Saa1, Saa2) with no changes in hepatic protein, but discrete plasma augmentation by the gene inactivation. Higher levels of malonyldialdehyde, apolipoprotein A1 and platelet activating factor-aryl esterase activity were also found in serum from Txndc5-deficient mice. However, no difference in the distribution of high-density lipoproteins (HDL)-mayor components and SAA was found between groups, and even the reactive oxygen species decreased in HDL coming from Txndc5-deficient mice. These results confirm the relation of this gene with hepatic steatosis and with a fasting metabolic derive remedying an acute phase response. Likewise, they pose a new role in modulating the nature of HDL particles, and SAA-containing HDL particles are not particularly oxidized.

PDI family thioredoxin from disk abalone (Haliotis discus discus): Responses to stimulants (PAMPs, bacteria, and viral) and functional characterization

Thioredoxin, a highly conserved class of proteins involved in redox signaling, is found in a range of organisms from bacteria to higher-level eukaryotes. Thioredoxin acts as an active regulatory enzyme to eliminate excessive reactive oxygen species, thereby preventing cellular damage. In this study, the cDNA sequence of thioredoxin domain-containing 5 (AbTXNDC5) from the disk abalone transcriptomic database was characterized. An in silico analysis of AbTXNDC5 was performed, and its spatial and temporal expression patterns in hemocytes and gills in response to bacteria (Vibrio parahaemolyticus, Listeria monocytogenes), viral hemorrhagic septicemia virus, and pathogen-associated molecular pattern molecules were observed. Furthermore, AbTXNDC5 expression was examined in different developmental stages. Functional assays to explore insulin disulfide reduction, anti-apoptotic activity, and protection against hypoxic cell death of AbTXNDC5 were conducted through recombinant proteins or overexpression in cells. AbTXNDC5 contains a 1179-bp open reading frame coding for 392 amino acids. Conserved thiol-disulfide cysteine residues within two Cys-X-X-Cys motifs were found in AbTXNDC5. Quantitative real-time polymerase chain reaction indicated that healthy digestive tract and hemocyte tissues expressed high levels of AbTXNDC5 mRNA, which may protect the host from invading pathogens. Immune-challenged abalone hemocytes and gills exhibited upregulated expression of AbTXNDC5 at different time points. rAbTXNDC5 also exhibited a functional insulin disulfide reductase activity. AbTXNDC5 conferred protection to cultured cells from apoptosis and hypoxia-induced stress_, compared to the pcDNA3.1⁽⁺⁾ transfected control cells. Therefore, AbTXNDC5 can be considered an important gene in abalones in relation to the primary immune system and regulation of redox homeostasis and confers protection from stress.

The NRF2, Thioredoxin, and Glutathione System in Tumorigenesis and Anticancer Therapies

Cancer remains an elusive, highly complex disease and a global burden. Constant change by acquired mutations and metabolic reprogramming contribute to the high inter- and intratumor heterogeneity of malignant cells, their selective growth advantage, and their resistance to anticancer therapies. In the modern era of integrative biomedicine, realizing that a personalized approach could benefit therapy treatments and patients' prognosis, we should focus on cancer-driving advantageous modifications. Namely, reactive oxygen species (ROS), known to act as regulators of cellular metabolism and growth, exhibit both negative and positive activities, as do antioxidants with potential anticancer effects. Such complexity of oxidative homeostasis is sometimes overseen in the case of studies evaluating the effects of potential anticancer antioxidants. While cancer cells often produce more ROS due to their increased growth-favoring demands, numerous conventional anticancer therapies exploit this feature to ensure selective cancer cell death triggered by excessive ROS levels, also causing serious side effects. The activation of the cellular NRF2 (nuclear factor erythroid 2 like 2) pathway and induction of cytoprotective genes accompanies an increase in ROS levels. A plethora of specific targets, including those involved in thioredoxin (TRX) and glutathione (GSH) systems, are activated by NRF2. In this paper, we briefly review preclinical research findings on the interrelated roles of the NRF2 pathway and TRX and GSH systems, with focus given to clinical findings and their relevance in carcinogenesis and anticancer treatments.

HERG1 promotes esophageal squamous cell carcinoma growth and metastasis through TXNDC5 by activating the PI3K/AKT pathway

Background

The human ether a-go-go-related gene 1 (HERG1) is involved in tumor progression; however, its role in esophageal squamous cell carcinoma (ESCC) is not well studied. This study investigated HERG1 function in ESCC progression and elucidated the underlying mechanisms.

Methods

The prognostic value of HERG1 was determined by immunohistochemistry in ESCC biopsies. Cell growth and proliferation were analyzed by colony formation and methyl thiazolyl tetrazolium assays. Cell migration and invasion were analyzed by wound healing and Boyden transwell assays. Epithelial-mesenchymal transition (EMT) was evaluated by immunoblotting and quantitative polymerase chain reaction (qPCR). A xenograft mouse model was used to validate the tumorigenic and metastatic roles of HERG1 in vivo.

Results

HERG1 expression was overall higher in ESCC tissues compared to adjacent non-tumor tissues. A retrospective analysis of 349 patients with ESCC (stages I–IV) confirmed increased HERG1 expression was associated with disease progression and higher mortality rate. The overall survival of the patients was significantly worse when their tumors displayed higher HERG1 expression. HERG1 knockdown reduced tumor growth and metastasis in athymic mice. HERG1 affected the proliferation, migration, and invasion of two ESCC cell lines (TE-1 and KYSE-30). Changes in HERG1 expression affected the expression of cell cycle- and EMT-related proteins; these effects were reversed by altering the expression of thioredoxin domain-containing protein 5 (TXNDC5), which is also associated with the clinicopathological characteristics of patients with ESCC and is relevant to HERG1 in pathological biopsies. Additionally, HERG1 expression altered phosphoinositide 3-kinase (PI3K) and AKT phosphorylation, thereby affecting TXNDC5 expression.

Conclusions

HERG1 contributes to poor prognosis in patients with ESCC by promoting ESCC cell proliferation, migration, and invasion via TXNDC5 through the PI3K/AKT signaling pathway. Our findings provided novel insights into the pathology of ESCC and role of HERG1 in tumor progression, suggesting that targeting HERG1 has potential diagnostic and therapeutic value for ESCC treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1284-y) contains supplementary material, which is available to authorized users.

A critical role of the thioredoxin domain containing protein 5 (TXNDC5) in redox homeostasis and cancer development

Correct folding of nascent peptides occurs in the endoplasmic reticulum (ER). It is a complicate process primarily accomplished by the coordination of multiple redox proteins including members of the protein disulfide isomerase (PDI) family. As a critical member of the PDI family, thioredoxin domain containing protein 5 (TXNDC5) assists the folding of newly synthesized peptides to their mature form through series of disulfide bond exchange reactions. Interestingly, TXNDC5 is frequently found overexpressed in specimens of many human diseases including various types of cancer. In this review, we summarized the biochemical function of TXNDC5 in mammalian cells and the recent progress on the understanding of its role and molecular mechanisms in cancer development. Findings of TXNDC5 in the activation of intracellular signaling pathways, stimulation of cell growth & proliferation, facilitation of cell survival and modulation of extracellular matrix to affect cancer cell invasion and metastasis are reviewed. These published studies suggest that strategies of targeting TXNDC5 can be developed as potentially valuable methods for the treatment of certain types of cancer in patients.