XBP1-s promotes colorectal cancer cell proliferation by inhibiting TAp73 transcriptional activity

Gut microbiota modulate intestinal inflammation by endoplasmic reticulum stress-autophagy-cell death signaling axis

The intestinal tract, a complex organ responsible for nutrient absorption and digestion, relies heavily on a balanced gut microbiome to maintain its integrity. Disruptions to this delicate microbial ecosystem can lead to intestinal inflammation, a hallmark of inflammatory bowel disease (IBD). While the role of the gut microbiome in IBD is increasingly recognized, the underlying mechanisms, particularly those involving endoplasmic reticulum (ER) stress, autophagy, and cell death, remain incompletely understood. ER stress, a cellular response to various stressors, can trigger inflammation and cell death. Autophagy, a cellular degradation process, can either alleviate or exacerbate ER stress-induced inflammation, depending on the specific context. The gut microbiome can influence both ER stress and autophagy pathways, further complicating the interplay between these processes. This review delves into the intricate relationship between ER stress, autophagy, and the gut microbiome in the context of intestinal inflammation. By exploring the molecular mechanisms underlying these interactions, we aim to provide a comprehensive theoretical framework for developing novel therapeutic strategies for IBD. A deeper understanding of the ER stress-autophagy axis, the gut microbial-ER stress axis, and the gut microbial-autophagy axis may pave the way for targeted interventions to restore intestinal health and mitigate the impact of IBD.

IRE1α-mediated UPR activation in gastrointestinal cancers: Adaptive mechanisms and therapeutic potential

The endoplasmic reticulum (ER) plays a crucial role in protein synthesis, folding and quality control. Disruptions in these processes lead to ER stress (ERS) and activate the unfolded protein response (UPR) to restore cellular homeostasis. In gastrointestinal cancers, inositol-requiring enzyme 1α (IRE1α) is a key regulator of the UPR, enabling cancer cells to adapt to hostile conditions such as hypoxia, oxidative stress and chemotherapy. Elevated IRE1α activity supports tumor survival, progression and metastasis by mitigating ERS-induced apoptosis. However, targeting IRE1α signaling presents a promising therapeutic strategy by impairing cancer cell adaptation to stress, offering promising therapeutic opportunities for gastrointestinal cancers.

Regulatory function of endoplasmic reticulum stress in colorectal cancer: Mechanism, facts, and perspectives

Colorectal cancer (CRC) is an exceedingly common and profoundly impactful malignancy of the digestive system, posing a grave threat to human health. Endoplasmic reticulum stress (ERS) is an intracellular biological reaction that mobilizes the unfolded protein response (UPR) to tackling dysregulation in protein homeostasis. This process subtly modulates the cell to either restore normal cellular function or steer it towards apoptosis. The high metabolic demands of CRC cells sculpt a rigorous tumor microenvironment (TME), compelling CRC cells to experience ERS. Adaptive responses induced by mild ERS furnish the necessary conditions for the survival of CRC cells, whereas the cell death mechanisms triggered by sustained ERS could be considered a prospective strategy for cancer therapy. Considering the complex regulation of ERS in cancer development, this article offers a comprehensive review of the molecular mechanisms through which ERS influences CRC fate. It provides crucial insights for exploring the role of ERS in the occurrence and progression of CRC, laying a new theoretical foundation for devising precise therapeutic strategies targeting ERS. Furthermore, by synthesizing extensive clinical and preclinical studies, we delve into therapeutic strategies targeting ERS, including the potential of targeting ERS in immunotherapy, the utilization of native compounds, advancements in proteasome inhibitors, and the potential synergies of these strategies with traditional chemotherapy agents and emerging therapeutic approaches.

Brain-targeted delivery of neuroprotective survival gene minimizing hematopoietic cell contamination: implications for Parkinson's disease treatment

BACKGROUND

Neurodegenerative diseases, including Parkinson's disease, Amyotropic Lateral Sclerosis (ALS) and Alzheimer's disease, present significant challenges for therapeutic development due to drug delivery restrictions and toxicity concerns. Prevailing strategies often employ adeno-associated viral (AAV) vectors to deliver neuroprotective survival genes directly into the central nervous system (CNS). However, these methods have been limited by triggering immunogenic responses and risk of tumorigenicity, resulting from overexpression of survival genes in peripheral blood mononuclear cells (PBMC), thereby increasing the risk of tumorigenicity in specific immune cells. Thus, by coding selectively suppressive microRNA (miRNA) target sequences in AAV genome, we designed CNS-targeted neuroprotective gene expression vector system without leakage to blood cells.

METHODS

To minimize the potential for transgene contamination in the blood, we designed a CNS-specific AAV system. Our system utilized a self-complementary AAV (scAAV), encoding a quadruple repeated target sequence of the hematopoietic cell-specific miR142-3p at the 3' untranslated region (UTR). As a representative therapeutic survival gene for Parkinson's disease treatment, we integrated DX2, an antagonistic splice variant of the apoptotic gene AIMP2, known to be implicated in Parkinson's disease, into the vector.

RESULTS

This configuration ensured that transgene expression was stringently localized to the CNS, even if the vector found its way into the blood cells. A single injection of scAAV-DX2 demonstrated marked improvement in behavior and motor activity in animal models of Parkinson's disease induced by either Rotenone or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Importantly, comprehensive preclinical data adhering to Good Laboratory Practice (GLP) standards revealed no adverse effects in the treated animals.

CONCLUSIONS

Our CNS-specific vector system, which encodes a survival transgene DX2, signifies a promising avenue for safe gene therapy, avoiding unintended expression of survival gene in blood cells, applicable to various neurodegenerative diseases.

XBP1s acts as a transcription factor of IRE1α and promotes proliferation of colon cancer cells

Upon ER stress, IRE1α is activated to splice XBP1 mRNA to generate XBP1s, a transcription factor that induces the expression of genes to cope with the stress. Expression of IRE1α is elevated in cancers and the IRE1α-XBP1s axis plays an important role in proliferation of cancer cells. However, the underlying mechanism is not well known. We found that ER stressors induced the expression of IRE1α, which was inhibited by depletion of XBP1s. XBP1s bound IRE1α promoter and initiated the transcription of IRE1α. These data indicate that XBP1s acts as a transcription factor of IRE1α. Overexpression of XBP1s increased the phosphorylation of JNK, a substrate of IRE1α kinase, which was inhibited by IRE1α kinase inhibitor Kira8. Overexpression of XBP1s also activated the regulated IRE1-dependent decay of mRNAs, which was suppressed by IRE1α RNase inhibitor STF083010. Moreover, we found that expression of XBP1s promoted proliferation of colon cancer cells, which was abrogated by Kira8 and STF083010. The results suggest that XBP1s functions to induce IRE1α expression and promote cancer cell proliferation. Our findings reveal a previously unknown mechanism of IRE1α expression by XBP1s and highlight the role of this regulation in proliferation of colon cancer cells, suggesting that IRE1α-targeting is a potential therapeutic strategy for colon cancer.

Spliced X-Box binding protein 1 predicts satisfying responsiveness and survival benefit toward bortezomib-based therapy in multiple myeloma patients

OBJECTIVE

Spliced X-Box binding protein 1 (sXBP1) modulates malignant cell activities and enhances the bortezomib sensitivity in multiple myeloma (MM) cells, while its clinical value in MM patients remains elusive. Hence, the current study aimed to explore this issue, particularly the correlation of sXBP1 with treatment outcomes of bortezomib-based therapy in MM patients.

METHODS

Totally, 97 newly-diagnosed MM patients undergoing bortezomib-based therapy, 20 disease controls (DCs), and 20 health controls (HCs) were enrolled. Bone marrow plasma cell samples were acquired to determine sXBP1 by RT-qPCR.

RESULTS

sXBP1 was lowest in MM patients, followed by DCs, and highest in HCs (P < 0.001). Beyond that, sXBP1 discriminated MM patients from DCs with area under curve (AUC) of 0.728 (95% confidence interval (CI): 0.610-0.847) and HCs with AUC of 0.855 (95% CI: 0.771-0.939). sXBP1 was negatively associated with t (4; 14) (P = 0.047), Revised International Staging System stage (P = 0.008). There was a trend that sXBP1 was negatively correlated with β₂-MG, LDH, and t (14; 16) (without statistical significance). sXBP1 was higher in patients with complete response (CR) compared to those with non-CR (P = 0.017) and higher in patients with objective response rate (ORR) compared to those with non-ORR (P = 0.006). sXBP1 (high vs. low) was linked with longer progression-free survival (PFS) (P = 0.011) and overall survival (P = 0.045) in MM patients. Additionally, sXBP1 (high vs. low) (P = 0.025) independently estimated a longer PFS.

CONCLUSION

sXBP1 forecasts a favorable treatment response and survival benefit toward bortezomib-based therapy in multiple myeloma patients.

Spliced or Unspliced, That Is the Question: The Biological Roles of XBP1 Isoforms in Pathophysiology

X-box binding protein 1 (XBP1) is a member of the CREB/ATF basic region leucine zipper family transcribed as the unspliced isoform (XBP1-u), which, upon exposure to endoplasmic reticulum stress, is spliced into its spliced isoform (XBP1-s). XBP1-s interacts with the cAMP response element of major histocompatibility complex class II gene and plays critical role in unfolded protein response (UPR) by regulating the transcriptional activity of genes involved in UPR. XBP1-s is also involved in other physiological pathways, including lipid metabolism, insulin metabolism, and differentiation of immune cells. Its aberrant expression is closely related to inflammation, neurodegenerative disease, viral infection, and is crucial for promoting tumor progression and drug resistance. Meanwhile, recent studies reported that the function of XBP1-u has been underestimated, as it is not merely a precursor of XBP1-s. Instead, XBP-1u is a critical factor involved in various biological pathways including autophagy and tumorigenesis through post-translational regulation. Herein, we summarize recent research on the biological functions of both XBP1-u and XBP1-s, as well as their relation to diseases.

MiRNA-136-5p Sensitizes Liver Cancer Cells to Docetaxel by Targeting P53 and Enhances Cell Migration

We aimed to explore whether microRNA (miRNA)-136-5p modulates P53 expression, and affects the efficacy of docetaxel treatment for liver cancer. miRNA array screened the differentially expressed miRNAs in biopsy tissues of liver cancer patients, and the expression of miR-136-5p and P53 in tissues and cells by RT-PCR. Following docetaxel treatment, through increased- and decreased-function method, we detected the impact of the miRNA on cell progression, as well as the sensitivity of docetaxel through MTT assay and colony formation experiment. The correlation between miR-136-5p and P53 was evaluated. The expression of miR-136-5p in liver cancer cells is up-regulated, which is consistent with the results of bioinformatics analysis. Further, miR-136-5p overexpression promoted cell proliferation and migration, and sensitized liver cancer cells to docetaxel. Interestingly, P53 was indicated to bind to miR-136-5p, and P53 participated in the up-regulation of MMP10 induced by miR-136-5p. miR-136-5p enhances the sensitivity to docetaxel in liver cancer and thus could be a biomarker for the treatment against liver cancer.

The role of XBP-1-mediated unfolded protein response in colorectal cancer progression-a regulatory mechanism associated with lncRNA-miRNA-mRNA network

BACKGROUND

We aim to identify the expression and analyze the molecular action of dysregulated lncRNA-miRNA mediated by XBP-1 in colorectal cancer (CRC).

METHODS

Here, we identified XBP-1-mediated dysregulated lncRNAs and miRNAs in CRC by bioinformatics analysis. The expression level of lncRNAs and miRNA was measured using quantitative real time PCR, and the expression of XBP-1, as well as apoptosis-related proteins, were detected by western blot. CCK-8 and TUNEL assays were performed to determine cell proliferation and apoptosis, respectively. Luciferase reporter assay was conducted to verify the binding relationship among lncRNA-miRNA-XBP-1. BALB/c nude mice were inoculated subcutaneously with HCT116 cells to establish tumor-bearing mice model. Histological analysis was carried out by HE staining and immunohistochemical staining.

RESULTS

Six downregulated lncRNAs (SLFNL1-AS1, KCNQ1OT1, NEAT1, XIST, AC016876.2, AC026362.1), four dysregulated miRNAs (miR-500a-3p, miR-370-3p, miR-2467-3p, miR-512-3p) and upregulated XBP-1 were identified in CRC cell lines. Gain- and loss-of-function experiments showed that overexpression of KCNQ1OT1/XIST promoted cell proliferation and suppressed cell apoptosis. In addition, overexpression of KCNQ1OT1/XIST partly abolished the inhibitory effects of XBP-1u knockdown or tunicamycin, an activator of endoplasmic reticulum stress, on CRC cell viability loss and apoptosis. Furthermore, KCNQ1OT1/XIST aggravated tumor growth in vivo by regulating endoplasmic reticulum stress and cell apoptosis.

CONCLUSIONS

This study has constructed lncRNA-miRNA-mRNA networks based on XBP-1 in CRC, and disclosed the regulatory mechanism of action, providing a set of pivotal biomarkers for future molecular investigation and targeted treatment of CRC.

Roles of XBP1s in Transcriptional Regulation of Target Genes

The spliced form of X-box binding protein 1 (XBP1s) is an active transcription factor that plays a vital role in the unfolded protein response (UPR). Under endoplasmic reticulum (ER) stress, unspliced Xbp1 mRNA is cleaved by the activated stress sensor IRE1α and converted to the mature form encoding spliced XBP1 (XBP1s). Translated XBP1s migrates to the nucleus and regulates the transcriptional programs of UPR target genes encoding ER molecular chaperones, folding enzymes, and ER-associated protein degradation (ERAD) components to decrease ER stress. Moreover, studies have shown that XBP1s regulates the transcription of diverse genes that are involved in lipid and glucose metabolism and immune responses. Therefore, XBP1s has been considered an important therapeutic target in studying various diseases, including cancer, diabetes, and autoimmune and inflammatory diseases. XBP1s is involved in several unique mechanisms to regulate the transcription of different target genes by interacting with other proteins to modulate their activity. Although recent studies discovered numerous target genes of XBP1s via genome-wide analyses, how XBP1s regulates their transcription remains unclear. This review discusses the roles of XBP1s in target genes transcriptional regulation. More in-depth knowledge of XBP1s target genes and transcriptional regulatory mechanisms in the future will help develop new therapeutic targets for each disease.

XBP1- IGFBP3 Signaling Pathway Promotes NSCLC Invasion and Metastasis

Lung cancer is the most frequently diagnosed cancer and the main cause of cancer death in the world. X-box binding protein 1 (XBP1), which is an important transcription factor involved in regulating the unfolded protein response (UPR) during endoplasmic reticulum (ER) stress, might act as a potent oncogenic protein in the processes of tumorigenesis, tumor proliferation and metastasis in various cancers. However, the clinical significance and pathological role of XBP1 in non-small cell lung cancer (NSCLC) remains unknown. In this study, we investigated the expression of XBP1s protein in the 104 NSCLC tumor tissues and matched adjacent normal lung tissues (ANLT) by Immunohistochemical (IHC), and we found overexpressed XBP1s protein was associated with NSCLC TNM stages, lymph node metastasis and poor prognosis. The further gain-and loss-of-function experiments indicated overexpression of XBP1s protein promoted cell invasion, migration and metastasis both in vitro and in vivo. Further study showed XBP1s protein could upregulate insulin-like growth factor binding protein-3 (IGFBP3) expression, and regulated NSCLC cells invasion and metastasis by regulating IGFBP3. Taken together, XBP1s protein is markedly overexpressed in NSCLC and serves as an oncogene that play a critical role in NSCLC tumorigenesis and development. Importantly, XBP1s protein might not only be a potential biomarker for metastasis and prognosis but also a potential therapeutic target in NSCLC.

miRNA-mRNA Regulatory Network Reveals miRNAs in HCT116 in Response to Folic Acid Deficiency via Regulating Vital Genes of Endoplasmic Reticulum Stress Pathway

Moderate folic acid (FA) intake is an effective strategy that slows colorectal cancer (CRC) progression. However, high consumption of FA may trigger the transition of precancerous tissue towards malignancy. MicroRNAs (miRNAs) are considered to be potential biomarkers of CRC. Thus, identification of miRNAs of dysregulated genes in CRC cells by detailed analysis of mRNA and miRNA expression profile in the context of FA deficiency could substantially increase our understanding of its oncogenesis. mRNA-seq and miRNA-seq analyses were utilized to investigate the expression of miRNAs in FA-deficient CRC cell line–HCT116 through massive parallel sequencing technology. A total of 38 mRNAs and 168 miRNAs were identified to be differentially expressed between CRC groups with or without FA deficiency. We constructed an miRNA-mRNA network for the vital regulatory miRNAs altered in FA-deficient CRC cells. The mRNAs and miRNAs validated by Western blotting and RT-qPCR were consistent with the sequencing results. Results showed that FA deficiency upregulated some miRNAs thereby inhibiting the expression of critical genes in the endoplasmic reticulum (ER) stress pathway. Dysregulated miRNAs in our miRNA-mRNA network could contribute to CRC cell in response to deficient FA. This work reveals novel molecular targets that are likely to provide therapeutic interventions for CRC.

Unfolded protein response in colorectal cancer

Colorectal cancer (CRC) is a gastrointestinal malignancy originating from either the colon or the rectum. A growing number of researches prove that the unfolded protein response (UPR) is closely related to the occurrence and progression of colorectal cancer. The UPR has three canonical endoplasmic reticulum (ER) transmembrane protein sensors: inositol requiring kinase 1 (IRE1), pancreatic ER eIF2α kinase (PERK), and activating transcription factor 6 (ATF6). Each of the three pathways is closely associated with CRC development. The three pathways are relatively independent as well as interrelated. Under ER stress, the activated UPR boosts the protein folding capacity to maximize cell adaptation and survival, whereas sustained or excessive ER triggers cell apoptosis conversely. The UPR involves different stages of CRC pathogenesis, promotes or hinders the progression of CRC, and will pave the way for novel therapeutic and diagnostic approaches. Meanwhile, the correlation between different signal branches in UPR and the switch between the adaptation and apoptosis pathways still need to be further investigated in the future.

X-box binding protein 1 (XBP1) function in diseases

The accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) causes endoplasmic reticulum stress (ERS), which is characteristic of cells with high levels of secretory activity and is involved in a variety of diseases. In response to ERS, cells initiate an adaptive process named the unfolding protein response (UPR) to maintain intracellular homeostasis and survival. However, long term and unresolved ERS can also induce apoptosis. As the most conserved signaling branch of UPR, the IRE1-XBP1 pathway plays an important role in both physiological and pathological states, and its activity has a profound impact on disease progression and prognosis. Here, the latest research progress of IRE1-XBP1 pathway in cancer, metabolic diseases, and other diseases was briefly introduced, and the relationship between several diseases and this pathway was analyzed. Besides, the new understanding and prospect of IRE1-XBP1 pathway regulating male reproduction were reviewed.

Use of Small-molecule Inhibitory Compound of PERK-dependent Signaling Pathway as a Promising Target-based Therapy for Colorectal Cancer

BACKGROUND

Colorectal cancer constitutes one of the most common cancer with a high mortality rate. The newest data has reported that activation of the pro-apoptotic PERK-dependent unfolded protein response signaling pathway by small-molecule inhibitors may constitute an innovative anti-cancer treatment strategy.

OBJECTIVE

In the presented study, we evaluated the effectiveness of the PERK-dependent unfolded protein response signaling pathway small-molecule inhibitor 42215 both on HT-29 human colon adenocarcinoma and CCD 841 CoN normal human colon epithelial cell lines.

METHODS

Cytotoxicity of the PERK inhibitor was evaluated by the resazurin-based and lactate dehydrogenase (LDH) tests. Apoptotic cell death was measured by flow cytometry using the FITCconjugated Annexin V to indicate apoptosis and propidium iodide to indicate necrosis as well as by colorimetric caspase-3 assay. The effect of tested PERK inhibitor on cell cycle progression was measured by flow cytometry using the propidium iodide staining. The level of the phosphorylated form of the eukaryotic initiation factor 2 alpha was detected by the Western blot technique.

RESULTS

Obtained results showed that investigated PERK inhibitor is selective only toward cancer cells, since inhibited their viability in a dose- and time-dependent manner and induced their apoptosis and G2/M cell cycle arrest. Furthermore, 42215 PERK inhibitor evoked significant inhibition of eIF2α phosphorylation within HT-29 cancer cells.

CONCLUSION

Highly-selective PERK inhibitors may provide a ground-breaking, anti-cancer treatment strategy via activation of the pro-apoptotic branch of the PERK-dependent unfolded protein response signaling pathway.

EGFR targeting enhances the efficiency of chemotherapy through inhibiting IRE1α-XBP1s pathway in colorectal cancer cells

Targeting EGFR combined with chemotherapy is one of the most valuable therapeutic strategies in colorectal cancer. However, resistance remains a major obstacle to improve efficacy. IRE1α-XBP1s signaling pathway is activated in many malignant tumors, and plays important roles in chemoresistance. Therefore, IRE1α-XBP1s might be a potential target to overcome the chemoresistance in colorectal cancer. In this study, we detected the activation of IRE1α-XBP1s signaling in patient cancer tissues and colorectal cancer cell lines. The phosphorylation level of IRE1α and the spliced XBP1s were aberrantly elevated in colorectal cancer, and IRE1α-XBP1s signaling activation was correlated with high EGFR expression. By overexpression of EGFR protein or activation by EGF treatment, we found that EGFR activation could enhance the phosphorylation of IRE1α and spliced XBP1s expression. On the contrary, inhibition of EGFR decreased the IRE1α-XBP1s signaling. Further, we examined the downstream signaling pathways regulated by EGFR. Inhibition of ERK activity could reverse the EGFR induced IRE1α-XBP1s activation. Co-IP confirmed the physical interaction of ERK and IRE1α. Cell growth and colony formation assay showed that the inhibition of IRE1α activity could suppress EGFR driven colorectal cancer cell proliferation. Furthermore, we found that oxaliplatin could activate IRE1α-XBP1s signaling, and combination with cetuximab partially reversed the activation. Inhibition of EGFR signaling could enhance the efficacy of oxaliplatin in vitro and in vivo. Our results showed that IRE1α RNase activity is aberrantly elevated in colorectal cancer, and EGFR signaling could activate IRE1α/XBP1s possibly through EGFR-MEK-ERK pathway. IRE1α-XBP1s pathway might involve in EGFR driven tumor cell proliferation. Cetuximab could partially recover oxaliplatin-induced IRE1α-XBP1s activation, and therefore enhance the anti-tumor efficacy of oxaliplatin. Our findings declare a new mechanism that targeting EGFR could inhibit chemotherapy-induced IRE1α-XBP1s activation and therefore enhance the efficacy.

miR-34c-5p modulates X-box-binding protein 1 (XBP1) expression during the adaptive phase of the unfolded protein response

During endoplasmic reticulum (ER) stress conditions, an adaptive signaling network termed the unfolded protein response (UPR) is activated. The UPR's function is to increase ER protein-folding capacity in order to attenuate ER stress, restore ER homeostasis, and, most importantly, promote cell survival. X-box-binding protein 1 (XBP1) is one component of the UPR and is a proadaptive transcription factor that is subject to transcriptional, post-transcriptional, and post-translational control. In the present study, we identified a post-transcriptional mechanism mediated by miR-34c-5p that governs the expression of both the spliced (active) and unspliced (latent) forms of XBP1 mRNAs. We showed that miR-34c-5p directly attenuates spliced XBP1 (XBP1s) mRNA levels during ER stress and thus regulates the proadaptive component of the UPR that is mediated by XBP1s without interfering with the induction of apoptotic responses.-Bartoszewska, S., Cabaj, A., Dąbrowski, M., Collawn, J. F., Bartoszewski, R. miR-34c-5p modulates X-box-binding protein 1 (XBP1) expression during the adaptive phase of the unfolded protein response.