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

XBP1: A key regulator in breast cancer development and treatment

X-box binding protein 1 (XBP1), as a transcription factor, plays pivotal role in unfolded protein response (UPR), which is activated in response to endoplasmic reticulum (ER) stress to restore ER homeostasis. IRE1α/XBP1 pathway is a key component of UPR, and the expression levels of XBP1 can dictate the fate of cells under ER stress, either promoting survival or driving apoptosis. High expression of XBP1 in breast tumors is closely associated with poor prognosis. The paper elucidates the biological functions of XBP1 and its involvement in UPR, while also surveying the latest research on how XBP1 influences immunity, metabolism, apoptosis, angiogenesis, and the invasive and migratory behaviors of breast cancer cells. Moreover, it contemplates the potential of XBP1 as a therapeutic target for breast cancer treatment.

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.

Innovative strategies to optimise colorectal cancer immunotherapy through molecular mechanism insights

Background

Colorectal cancer (CRC) is a leading cause of cancer-related deaths globally. The heterogeneity of the tumor microenvironment significantly influences patient prognosis, while the diversity of tumor cells shapes its unique characteristics. A comprehensive analysis of the molecular profile of tumor cells is crucial for identifying novel molecular targets for drug sensitivity analysis and for uncovering the pathophysiological mechanisms underlying CRC.

Methods

We utilized single-cell RNA sequencing technology to analyze 13 tissue samples from 4 CRC patients, identifying key cell types within the tumor microenvironment. Intercellular communication was assessed using CellChat, and a risk score model was developed based on eight prognostic genes to enhance patient stratification for immunotherapeutic approaches. Additionally, in vitro experiments were performed on DLX2, a gene strongly associated with poor prognosis, to validate its potential role as a therapeutic target in CRC progression.

Results

Eight major cell types were identified across the tissue samples. Within the tumor cell population, seven distinct subtypes were recognized, with the C0 FXYD5+ tumor cells subtype being significantly linked to cancer progression and poor prognosis. CellChat analysis indicated extensive communication among tumor cells, fibroblasts, and immune cells, underscoring the complexity of the tumor microenvironment. The risk score model demonstrated high accuracy in predicting 1-, 3-, and 5-year survival rates in CRC patients. Enrichment analysis revealed that the C0 FXYD5+ tumor cell subtype exhibited increased energy metabolism, protein synthesis, and oxidative phosphorylation, contributing to its aggressive behavior. In vitro experiments confirmed DLX2 as a critical gene associated with poor prognosis, suggesting its viability as a target for improving drug sensitivity.

Conclusion

In summary, this study advances our understanding of CRC progression by identifying critical tumor subtypes, molecular pathways, and prognostic markers that can inform innovative strategies for predicting and enhancing drug sensitivity. These findings hold promise for optimizing immunotherapeutic approaches and developing new targeted therapies, ultimately aiming to improve patient outcomes in CRC.

Endoplasmic reticulum stress and therapeutic strategies in metabolic, neurodegenerative diseases and cancer

The accumulation of unfolded or misfolded proteins within the endoplasmic reticulum (ER), due to genetic determinants and extrinsic environmental factors, leads to endoplasmic reticulum stress (ER stress). As ER stress ensues, the unfolded protein response (UPR), comprising three signaling pathways-inositol-requiring enzyme 1, protein kinase R-like endoplasmic reticulum kinase, and activating transcription factor 6 promptly activates to enhance the ER's protein-folding capacity and restore ER homeostasis. However, prolonged ER stress levels propels the UPR towards cellular demise and the subsequent inflammatory cascade, contributing to the development of human diseases, including cancer, neurodegenerative disorders, and diabetes. Notably, increased expression of all three UPR signaling pathways has been observed in these pathologies, and reduction in signaling molecule expression correlates with decreased proliferation of disease-associated target cells. Consequently, therapeutic strategies targeting ER stress-related interventions have attracted significant research interest. In this review, we elucidate the critical role of ER stress in cancer, metabolic, and neurodegenerative diseases, offering novel therapeutic approaches for these conditions.

Morin suppresses mTORc1/IRE-1α/JNK and IP3R-VDAC-1 pathways: Crucial mechanisms in apoptosis and mitophagy inhibition in experimental Huntington's disease, supported by in silico molecular docking simulations

AIMS

Endoplasmic reticulum stress (ERS) with aberrant mitochondrial-ER contact (MERC), mitophagy, and apoptosis are interconnected determinants in neurodegenerative diseases. Previously, we proved the potential of Morin hydrate (MH), a potent antioxidant flavonoid, to mitigate Huntington's disease (HD)-3-nitropropionic acid (3-NP) model by modulating glutamate/calpain/Kidins220/BDNF trajectory. Extending our work, we aimed to evaluate its impact on combating the ERS/MERC, mitophagy, and apoptosis.

METHODS

Rats were subjected to 3-NP for 14 days and post-treated with MH and/or the ERS inducer WAG-4S for 7 days. Disease progression was assessed by gross inspection and striatal biochemical, histopathological, immunohistochemical, and transmission electron microscopical (TEM) examinations. A molecular docking study was attained to explore MH binding to mTOR, JNK, the kinase domain of IRE1-α, and IP3R.

KEY FINDINGS

MH decreased weight loss and motor dysfunction using open field and rotarod tests. It halted HD degenerative striatal neurons and nucleus/mitochondria ultra-microscopic alterations reflecting neuroprotection. Mechanistically, MH deactivated striatal mTOR/IRE1-α/XBP1s&JNK/IP3R, PINK1/Ubiquitin/Mfn2, and cytochrome c/caspase-3 signaling pathways, besides enhancing p-PGC-1α and p-VDAC1. WAG-4S was able to ameliorate all effects initiated by MH to different extents. Molecular docking simulations revealed promising binding patterns of MH and hence its potential inhibition of the studied proteins, especially mTOR, IP3R, and JNK.

SIGNIFICANCE

MH alleviated HD-associated ERS, MERC, mitophagy, and apoptosis. This is mainly achieved by combating the mTOR/IRE1-α signaling, IP3R/VDAC hub, PINK1/Ubiquitin/Mfn2, and cytochrome c/caspase 3 axis to be worsened by WAG-4S. Molecular docking simulations showed the promising binding of MH to mTOR and JNK as novel identified targets.

PHD3 inhibits colon cancer cell metastasis through the occludin-p38 pathway

Prolyl hydroxylase 3 (PHD3) hydroxylates HIFα in the presence of oxygen, leading to HIFα degradation. PHD3 inhibits tumorigenesis. However, the underlying mechanism is not well understood. Herein, we demonstrate that PHD3 inhibits the metastasis of colon cancer cells through the occludin-p38 MAPK pathway independent of its hydroxylase activity. We find that PHD3 inhibits colon cancer cell metastasis in the presence of the PHD inhibitor DMOG, and prolyl hydroxylase-deficient PHD3(H196A) suppresses cell metastasis as well. PHD3 controls the stability of the tight junction protein occludin in a hydroxylase-independent manner. We further find that PHD3-inhibited colon cancer cell metastasis is rescued by knockdown of occludin and that occludin acts as a negative regulator of cell metastasis, implying that PHD3 suppresses metastasis through occludin. Furthermore, knockdown of occludin induces phosphorylation of p38 MAPK, and the p38 inhibitor SB203580 impedes cell migration and invasion induced by occludin knockdown, indicating that occludin functions through p38. Moreover, knockdown of occludin enhances the expression of MKK3/6, the upstream kinase of p38, while overexpression of occludin decreases its expression. Our results suggest that PHD3 inhibits the metastasis of colon cancer cells through the occludin-p38 pathway independent of its hydroxylase activity. These findings reveal a previously undiscovered mechanism underlying the regulation of cancer cell metastasis by PHD3 and highlight a noncanonical hydroxylase-independent function of PHD3 in the suppression of cancer cells.