Tropomyosin 2 Regulates Tumor Cell Proliferation, Immune Suppression, and Activation of the JNK Signaling Pathway in Colitis-Associated Cancer (CAC).

BACKGROUND: Tropomyosin 2 (TPM2) has been linked to the advancement of various tumor types, exhibiting distinct impacts on tumor progression. In our investigation, the primary objective was to identify the potential involvement of TPM2 in the development of colitis-associated cancer (CAC) using a mice model. METHODS: This study used lentiviral vector complex for TPM2 knockdown (sh-TPM2) and the corresponding negative control lentiviral vector complex (sh-NC) for genetic interference in mice. CAC was induced in mice using azoxymethane (AOM) and dextran sulfate sodium salt (DSS). This study included 6 groups of mice models: Control, Control+sh-NC, Control+sh-TPM2, CAC, CAC+sh-NC, and CAC+sh-TPM2. Subsequently, colon tissues were collected and assessed using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) for TPM2 mRNA levels and flow cytometry for infiltrating immune cells. Tumor number, size, and weight within colon tissues from CAC mice were measured and recorded. The hematoxylin-eosin staining was used for observing tissue pathology changes. The intestinal epithelial cells (IECs) were isolated and analyzed for cell proliferation. This analysis included examining the levels of 5-bromo-2-deoxyuridine (BrdU) and Ki-67 using immunohistochemistry. Additionally, the mRNA levels of proliferating cell nuclear antigen (PCNA) and Ki-67 were detected by qRT-PCR. This study also investigated the activation of the c-Jun N-terminal kinase (JNK) pathway using western blot analysis. Immunogenicity analyses were conducted using immunohistochemistry for F4/80 and flow cytometry. RESULTS: In 8-week-old mice, AOM injections and three cycles of DSS treatment induced TPM2 upregulation in tumor tissues compared to normal tissues (p < 0.05). Fluorescence-activated cell sorting (FACS)-isolated lamina CAC adenomas revealed macrophages and dendritic cells as primary TPM2 contributors (p < 0.001). Lentiviral TPM2 gene knockdown significantly reduced tumor numbers and sizes in CAC mice (p < 0.01, and p < 0.001), without invasive cancer cells. TPM2 suppression resulted in decreased IEC proliferation (p < 0.001) and reduced PCNA and Ki-67 expression (p < 0.05). Western blot analysis indicated reduced JNK pathway activation in TPM2-knockdown CAC mice (p < 0.05, p < 0.001). TPM2 knockdown decreased tumor-associated macrophage infiltration (p < 0.01) and increased CD3+ and CD8+ T cells (p < 0.01, and p < 0.001), with increased levels of regulator of inflammatory cytokines (CD44+, CD107a+) (p < 0.01, and p < 0.001), decreased levels of PD-1+ and anti-inflammatory factor (IL10+) (p < 0.01, and p < 0.001). CONCLUSIONS: Our results demonstrated that TPM2 knockdown suppressed the proliferation of CAC IECs, enhanced immune suppression on CAC IECs, and inhibited the JNK signaling pathway within the framework of CAC. These findings suggest TPM2 can serve as a potential therapeutic target for CAC treatment.

Chicken miR-126-5p negatively regulates antiviral innate immunity by targeting TRAF3.

Innate immunity plays an essential role in preventing the invasion of pathogenic microorganisms. However, innate immunity is a double-edged sword, whose excessive activation is detrimental to immune homeostasis and even leads to a "cytokine storm" of the infected host. The host develops a series of negative regulatory mechanisms to balance the immune response. Here, we report a negative regulatory mechanism of chicken innate immunity mediated by miRNA. In the GEO database, we found that miR-126-5p was markedly up-regulated in chickens infected by RNA viruses. Upregulation of miR-126-5p by RNA virus was then further shown via both a cell model and in vivo tests. Overexpression of miR-126-5p significantly inhibited the expression of interferon and inflammatory cytokine-related genes induced by RNA viruses. The opposite result was achieved after the knockdown of miR-126-5p expression. Bioinformatics analysis identified TRAF3 as candidate target gene of miR-126-5p. Experimentally, miR-126-5p can target TRAF3, as shown by the effects of miR-126-5p on the endogenous expression of TRAF3, and by the TRAF3 3'UTR driven luciferase reporter assay. Furthermore, we demonstrated that miR-126-5p negatively regulated innate immunity by blocking the MAVS-TRAF3-TBK1 axis, with a co-expression assay. Overall, our results suggest that miR-126-5p is involved in the negative regulation of chicken innate immunity, which might contribute to maintaining immune balance.

NANOG: a promising target for digestive malignant tumors.

NANOG has been extensively researched since its discovery by Chambers et al. NANOG is a homeodomain transcription factor and an essential regulator of embryonic stem cell (ESC) self-renewal, which inhibits differentiation. Cancer stem cells (CSCs) are a small subset of cells that are thought to drive uncontrolled tumor growth; CSCs retain the tumor capabilities of self-renewal and propagation. The existence of CSCs was recently shown by direct experimental evidence. NANOG is expressed in CSCs and ESCs, although it remains unclear whether ESCs and CSCs share similar mechanisms in the regulation of physical and biological processes. Several studies suggest that the expression level of NANOG is high in cancer tissues and low or absent in normal tissues. High levels of NANOG expression are associated with advanced stages of cancer and a poor prognosis, indicating that it plays a vital role in tumor transformation, tumorigenesis, and tumor metastasis. NANOG is part of a complex regulatory network that controls cell fate determination, proliferation, and apoptosis. NANOG cooperates with other regulators, such as microflora, transcription factors, and kinases, in cancer cells. NANOG might have a promising future in anti-cancer and other therapeutic treatments, which could improve human health.