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.

TIAM2S as a novel regulator for serotonin level enhances brain plasticity and locomotion behavior.

TIAM2S, the short form of human T-cell lymphoma invasion and metastasis 2, can have oncogenic effects when aberrantly expressed in the liver or lungs. However, it is also abundant in healthy, non-neoplastic brain tissue, in which its primary function is still unknown. Here, we examined the neurobiological and behavioral significance of human TIAM2S using the human brain protein panels, a human NT2/D1-derived neuronal cell line model (NT2/N), and transgenic mice that overexpress human TIAM2S (TIAM2S-TG). Our data reveal that TIAM2S exists primarily in neurons of the restricted brain areas around the limbic system and in well-differentiated NT2/N cells. Functional studies revealed that TIAM2S has no guanine nucleotide exchange factor (GEF) activity and is mainly located in the nucleus. Furthermore, whole-transcriptome and enrichment analysis with total RNA sequencing revealed that TIAM2S-knockdown (TIAM2S-KD) was strongly associated with the cellular processes of the brain structural development and differentiation, serotonin-related signaling, and the diseases markers representing neurobehavioral developmental disorders. Moreover, TIAM2S-KD cells display decreased neurite outgrowth and reduced serotonin levels. Moreover, TIAM2S overexpressing TG mice show increased number and length of serotonergic fibers at early postnatal stage, results in higher serotonin levels at both the serum and brain regions, and higher neuroplasticity and hyperlocomotion in latter adulthood. Taken together, our results illustrate the non-oncogenic functions of human TIAM2S and demonstrate that TIAM2S is a novel regulator of serotonin level, brain neuroplasticity, and locomotion behavior.

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

The short isoform of human TIAM2 has been shown to promote proliferation and invasion in various cancer cells. However, the roles of TIAM2S in immune cells in relation to tumor development have not been investigated. To characterize the effects of TIAM2S, we generated TIAM2S-overexpressing mouse lines and found that aged TIAM2S-transgenic (TIAM2S-TG) developed significantly higher occurrence of lymphocytic infiltration and tumorigenesis in various organs, including colon. In addition, TIAM2S-TG is more sensitized to AOM-induced colon tumor development, suggesting a priming effect toward tumorigenesis. In the light of our recent findings that TIAM2S functions as a novel regulator of cellular serotonin level, we found that serotonin, in addition to Cox2, is a unique inflammation marker presented in the colonic lesion sites in the aged TG animals. Furthermore, our results demonstrated that ectopic TIAM2S altered immunity via the expansion of T lymphocytes; this was especially pronounced in CD8+ T cells in combination with CXCL13/BCA-1 pro-inflammatory chemokine in the serum of TIAM2S-TG mice. Consequently, T lymphocytes and B cells were recruited to the lesion sites and stimulated IL-23/IL17A expression to form the tertiary lymphoid organs. Collectively, our research suggests that TIAM2S provokes a pro-inflammatory immune microenvironment permissive to colorectal tumorigenesis through the serotonin-induced immunomodulatory effects.

hnRNPM induces translation switch under hypoxia to promote colon cancer development.

BACKGROUND: Hypoxia suppresses global protein production, yet certain essential proteins are translated through alternative pathways to survive under hypoxic stress. Translation via the internal ribosome entry site (IRES) is a means to produce proteins under stress conditions such as hypoxia; however, the underlying mechanism remains largely uncharacterized. METHODS: Proteomic and bioinformatic analyses were employed to identify hnRNPM as an IRES interacting factor. Clinical specimens and mouse model of tumorigenesis were used for determining the expression and correlation of hnRNPM and its target gene. Transcriptomic and translatomic analyses were performed to profile target genes regulated by hnRNPM. FINDINGS: Hypoxia increases cytosolic hnRNPM binding onto its target mRNAs and promotes translation initiation. Clinical colon cancer specimens and mouse carcinogenesis model showed that hnRNPM is elevated during the development of colorectal cancer, and is associated with poor prognosis. Genome-wide transcriptomics and translatomics analyses revealed a unique set of hnRNPM-targeted genes involved in metabolic processes and cancer neoplasia are selectively translated under hypoxia. INTERPRETATION: These data highlight the critical role of hnRNPM-IRES-mediated translation in transforming hypoxia-induced proteome toward malignancy. FUND: This work was supported by the Ministry of Science and Technology, Taiwan (MOST 104-2320-B-006-042 to HSS and MOST 105-2628-B-001-MY3 to TMC).

Synthesis, DNA binding, and cytotoxicity of 1,4-bis(2-amino-ethylamino)anthraquinone-amino acid conjugates.

Two series of 1,4-bis(2-amino-ethylamino)anthraquinone-amino acid conjugates (BACs), ametantrone (AT)-amino acid conjugates (AACs) and mitoxantrone (MX)-amino acid conjugates (MACs), were designed and synthesized. The DNA binding of BACs was evaluated by DNA thermal denaturation experiment. In the series, the methionine-substituted BACs had the weakest DNA binding, while the lysine-substituted BACs had the highest T(m) values. The abilities of BACs to inhibit the growth of MCF-7, NCI-H460, SF-268, and PC-3 cell lines were determined. l-Met-MAC 16 and l-Lys-MAC 20 were the most potent growth inhibitors. MAC 16 was more cytotoxic than MX, whereas the T(m) of MAC 16 was much lower than that of MX. In contrast to MAC 16, l-Lys-MAC 20 demonstrated higher T(m) than MX. These data suggested that Met-BACs possessed a different pharmacological profile, in which the ability to stabilize DNA is not parallel to the ability to kill cancer cells, from that of AT and MX. The primary mechanism of cytotoxicity for MAC 16 was most likely through TOP2 poisoning. Therefore, MAC 16 may provide a lead for the development of novel generations of anthraquinone-type antitumor agents.

WRC-213, an l-methionine-conjugated mitoxantrone derivative, displays anticancer activity with reduced cardiotoxicity and drug resistance: identification of topoisomerase II inhibition and apoptotic machinery in prostate cancers.

Anthracyclines and anthracenediones are well-known cancer chemotherapeutic agents but their uses are limited with cardiotoxicity and drug resistance. Several l- and d-form amino acids were introduced into the anthraquinone skeleton and numerous derivatives were synthesized for the evaluation of anticancer activity. The screening tests showed that WRC-213, an l-methionine conjugation, was the most effective derivative to inhibit proliferative effect of human androgen-independent prostate cancer PC-3 cells (IC50=50 nM). In an extension evaluation, WRC-213 displayed a potent anti-proliferative activity in various cancer cell lines, including non-small cell lung cancer A549, androgen-independent prostate cancer DU145, colorectal cancer HT-29, breast cancer MCF-7 and hepatocellular carcinoma Hep3B and HepG2. It induced cell-cycle arrest at S and G2, but not mitotic phase, in PC-3 cells. The comet assay revealed that induction of DNA damage and inhibition of topoisomerase II were the primary insults. After the checkpoint arrest of the cell-cycle, WRC-213 induced the mitochondria-mediated intrinsic apoptotic pathway, including Mcl-1 cleavage, Bcl-2 down-regulation and activation of caspase-9/caspase-3 cascades. Survivin degradation and caspase-2 activation also contributed to WRC-213-induced apoptosis. Moreover, the assessment of cytotoxicity in H9c2 cardiomyocytes and drug resistance in NCI/ADR-RES cells demonstrated that WRC-213 showed much lower cardiotoxicity and P-glycoprotein-related resistance than those of mitoxantrone, etoposide and doxorubicin. In conclusion, it is suggested that WRC-213 is a potential topoisomerase II inhibitor with reduced cardiotoxicity and drug resistance. It inhibits topoisomerase II activity and induces chromosomal DNA strand breaks, leading to S and G2 arrest of the cell-cycle and activation of mitochondria-mediated apoptotic pathways.