TIAM2S Mediates Serotonin Homeostasis and Provokes a Pro-Inflammatory Immune Microenvironment Permissive for Colorectal Tumorigenesis

TIAM2S-positive microglia enhance inflammation and neurotoxicity through soluble ICAM-1-mediated immune priming

TIAM Rac1-associated GEF 2 short form (TIAM2S) as an oncoprotein alters the immunity of peripheral immune cells to construct an inflammatory tumor microenvironment. However, its role in the activation of microglia, the primary innate immune cells of the brain, and neuroinflammation remains unknown. This study investigated the mechanism underlying TIAM2S shapes immune properties of microglia to facilitate neuron damage. Human microglial clone 3 cell line (HMC3) and human brain samples were applied to determine the presence of TIAM2S in microglia by western blots and double immunostaining. Furthermore, TIAM2S transgenic mice combined with multiple reconstituted primary neuron-glial culture systems and a cytokine array were performed to explore how TIAM2S shaped immune priming of microglia and participated in lipopolysaccharide (LPS)-induced neuron damage. TIAM2S protein was detectable in HMC3 cells and presented in a small portion (~11.1%) of microglia in human brains referred to as TIAM2S-positive microglia. With the property of secreted soluble factor-mediated immune priming, TIAM2S-positive microglia enhanced LPS-induced neuroinflammation and neural damage in vivo and in vitro. The gain- and loss-of-function experiments showed soluble intercellular adhesion molecule-1 (sICAM-1) participated in neurotoxic immune priming of TIAM2S+ microglia. Together, this study demonstrated a novel TIAM2S-positive microglia subpopulation enhances inflammation and neurotoxicity through sICAM-1-mediated immune priming.

NSUN2 stimulates tumor progression via enhancing TIAM2 mRNA stability in pancreatic cancer

NSUN2 is a nuclear RNA methyltransferase which catalyzes 5-methylcytosine (m5C), a posttranscriptional RNA modification. Aberrant m5C modification has been implicated in the development of multiple malignancies. However, its function in pancreatic cancer (PC) needs to be elucidated. Herein, we determined that NSUN2 was overexpressed in PC tissues and related to aggressive clinical features. Silence of NSUN2 by lentivirus weakened the capability of proliferation, migration and invasion of PC cells in vitro and inhibited the growth and metastasis of xenograft tumors in vivo. Contrarily, overexpression of NSUN2 stimulated PC growth and metastasis. Mechanistically, m5C-sequencing (m5C-seq) and RNA-sequencing (RNA-seq) were carried out to identify downstream targets of NSUN2 and results showed that loss of NSUN2 led to decreased m5C modification level concomitant with reduced TIAM2 mRNA expression. Further validation experiments proved that NSUN2 silence accelerated the decay of TIAM2 mRNA in a YBX1-dependent manner. Additionally, NSUN2 exerted its oncogenic function partially through enhancing TIAM2 transcription. More importantly, disruption of the NSUN2/TIAM2 axis repressed the malignant phenotype of PC cells through blocking epithelial-mesenchymal transition (EMT). Collectively, our study highlighted the critical function of NSUN2 in PC and provided novel mechanistic insights into NSUN2/TIAM2 axis as promising therapeutic targets against PC.

Neurotransmitters: promising immune modulators in the tumor microenvironment

The tumor microenvironment (TME) is modified by its cellular or acellular components throughout the whole period of tumor development. The dynamic modulation can reprogram tumor initiation, growth, invasion, metastasis, and response to therapies. Hence, the focus of cancer research and intervention has gradually shifted to TME components and their interactions. Accumulated evidence indicates neural and immune factors play a distinct role in modulating TME synergistically. Among the complicated interactions, neurotransmitters, the traditional neural regulators, mediate some crucial regulatory functions. Nevertheless, knowledge of the exact mechanisms is still scarce. Meanwhile, therapies targeting the TME remain unsatisfactory. It holds a great prospect to reveal the molecular mechanism by which the interplay between the nervous and immune systems regulate cancer progression for laying a vivid landscape of tumor development and improving clinical treatment.

Effects of preoperative albumin-to-globulin ratio on overall survival and quality of life in esophageal cell squamous carcinoma patients: a prospective cohort study

OBJECTIVE

This study aimed to investigate the effect of preoperative albumin-to-globulin ratio (AGR) on overall survival (OS) and health-related quality of life in patients with esophageal cell squamous carcinoma (ESCC).

METHODS

Serum albumin and globulin were measured within one week before surgery. Multiple follow-ups were conducted among patients with ESCC in the study in order to assess their life quality. The method used in the study was a telephone interview. Quality of life was measured using the EORTC Quality of Life Questionnaire-Core Questionnaire (EORTC QLQ-C30, version 3.0) and Esophageal Cancer Module (EORTC QLQ- OES18).

RESULTS

A total of 571 ESCC patients were included in the study. The results illustrated that 5-year OS of high AGR group (74.3%) was better than the low one (62.3%) (P = 0.0068). Univariate and multivariate Cox regression analysis found that preoperative AGR (HR = 0.642, 95%CI: 0.444-0.927) are prognostic factor for patients with ESCC after surgery. In terms of quality of life, found that low AGR associated with increased postoperative time to deterioration (TTD) events in ESCC patients, and compared to low AGR, high AGR could delay the deterioration of emotional functioning(P = 0.001), dysphagia(P = 0.033), trouble with taste(P = 0.043) and speech problems(P = 0.043). After using the multivariate Cox regression analysis showed that high AGR could improve patients' emotional function (HR = 0.657, 95% CI: 0.507-0.852) and trouble with taste (HR = 0.706, 95% CI: 0.514-0.971).

CONCLUSIONS

Preoperative AGR in patients with ESCC after esophagectomy was positively correlated with overall survival rate and quality of life after operation.

Serotonin Pathway in Cancer

Serotonin (5-hydroxytryptamine, 5-HT) is a biogenic monoamine produced from the essential amino acid tryptophan. Serotonin's role as a neurotransmitter in the central nervous system and a motility mediator in the gastrointestinal tract has been well defined, and its function in tumorigenesis in various cancers (gliomas, carcinoids, and carcinomas) is being studied. Many studies have shown a potential stimulatory effect of serotonin on cancer cell proliferation, invasion, dissemination, and tumor angiogenesis. Although the underlying mechanism is complex, it is proposed that serotonin levels in the tumor and its interaction with specific receptor subtypes are associated with disease progression. This review article describes serotonin's role in cancer pathogenesis and the utility of the serotonin pathway as a potential therapeutic target in cancer treatment. Octreotide, an inhibitor of serotonin release, is used in well-differentiated neuroendocrine cancers, and the tryptophan hydroxylase (TPH) inhibitor, telotristat, is currently being investigated in clinical trials to treat patients with metastatic neuroendocrine tumors and advanced cholangiocarcinoma. Several in vitro studies have shown the anticancer effect of 5-HT receptor antagonists in various cancers such as prostate cancer, breast cancer, urinary bladder, colorectal cancer, carcinoid, and small-cell lung cancer. More in vivo studies are needed to assess serotonin's role in cancer and its potential use as an anticancer therapeutic target. Serotonin is also being evaluated for its immunoregulatory properties, and studies have shown its potential anti-inflammatory effect. Therefore, it would be of interest to explore the combination of serotonin antagonists with immunotherapy in the future.

Mechanisms and consequences of dysregulation of the Tiam family of Rac activators in disease

The Tiam family proteins - Tiam1 and Tiam2/STEF - are Rac1-specific Guanine Nucleotide Exchange Factors (GEFs) with important functions in epithelial, neuronal, immune and other cell types. Tiam GEFs regulate cellular migration, proliferation and survival, mainly through activating and directing Rac1 signalling. Dysregulation of the Tiam GEFs is significantly associated with human diseases including cancer, immunological and neurological disorders. Uncovering the mechanisms and consequences of dysregulation is therefore imperative to improving the diagnosis and treatment of diseases. Here we compare and contrast the subcellular localisation and function of Tiam1 and Tiam2/STEF, and review the evidence for their dysregulation in disease.