Autocrine pro-legumain promotes breast cancer metastasis via binding to integrin αvß3.

Tumor metastasis is the leading cause of cancer-associated mortality. Unfortunately, the underlying mechanism of metastasis is poorly understood. Expression of legumain (LGMN), an endo-lysosomal cysteine protease, positively correlates with breast cancer metastatic progression and poor prognosis. Here, we report that LGMN is secreted in the zymogen form by motile breast cancer cells. Through binding to cell surface integrin αvß3 via an RGD motif, the autocrine pro-LGMN activates FAK-Src-RhoA signaling in cancer cells and promotes cancer cell migration and invasion independent of LGMN protease activity. Either silencing LGMN expression or mutationally abolishing pro-LGMN‒αvß3 interaction significantly inhibits cancer cell migration and invasion in vitro and breast cancer metastasis in vivo. Finally, we developed a monoclonal antibody against LGMN RGD motif, which blocks pro-LGMN‒αvß3 binding, and effectively suppresses cancer cell migration and invasion in vitro and breast cancer metastasis in vivo. Thus, disruption of pro-LGMN‒integrin αvß3 interaction may be a potentially promising strategy for treating breast cancer metastasis.

Integrin ß7 Inhibits Colorectal Cancer Pathogenesis via Maintaining Antitumor Immunity.

Immune cell infiltration is important for predicting the clinical outcomes of colorectal cancer. Integrin ß7 (ITGB7), which is expressed on the surface of leukocytes, plays an essential role in the homing of immune cells to gut-associated lymphoid tissue and facilitating the retention of lymphocytes in gut epithelium; however, its role in colorectal cancer pathogenesis is poorly explored. Here, we found that the number of ß7+ cells decreased significantly in tumor tissue compared with adjacent normal tissue. ß7 expression decreased in tumor-derived compared with normal tissue-derived CD8+ T cells. With bulk RNA expression data from public platforms, we demonstrated that higher ITGB7 expression correlated with longer patient survival, higher cytotoxic immune cell infiltration, lower somatic copy-number alterations, decreased mutation frequency of APC and TP53, and better response to immunotherapy. The possible cell-cell interactions mediated by ITGB7 and its ligands MAdCAM-1, VCAM-1, and CDH1 were investigated using public single-cell RNA sequencing data. ITGB7 deficiency led to exaggerated tumorigenesis and progression in both Apcmin /+ spontaneous and MC38 orthotopic models of colorectal cancer, which could be due to a reduced infiltration of activated CD8+ T cells, effector memory CD8+ T cells, IFNγ+ CD8+ T cells, IFNγ+ natural killer cells, CD103+ dendritic cells, and other immune cell subsets that are essential players in antitumor immunity. In conclusion, our data revealed that ITGB7 could inhibit the tumorigenesis and progression of colorectal cancer by maintaining antitumor immunity.

CCRL2 promotes antitumor T-cell immunity via amplifying TLR4-mediated immunostimulatory macrophage activation.

Macrophages are the key regulator of T-cell responses depending on their activation state. C-C motif chemokine receptor-like 2 (CCRL2), a nonsignaling atypical receptor originally cloned from LPS-activated macrophages, has recently been shown to regulate immune responses under several inflammatory conditions. However, whether CCRL2 influences macrophage function and regulates tumor immunity remains unknown. Here, we found that tumoral CCRL2 expression is a predictive indicator of robust antitumor T-cell responses in human cancers. CCRL2 is selectively expressed in tumor-associated macrophages (TAM) with immunostimulatory phenotype in humans and mice. Conditioned media from tumor cells could induce CCRL2 expression in macrophages primarily via TLR4, which is negated by immunosuppressive factors. Ccrl2-/- mice exhibit accelerated melanoma growth and impaired antitumor immunity characterized by significant reductions in immunostimulatory macrophages and T-cell responses in tumor. Depletion of CD8+ T cells or macrophages eliminates the difference in tumor growth between WT and Ccrl2-/- mice. Moreover, CCRL2 deficiency impairs immunogenic activation of macrophages, resulting in attenuated antitumor T-cell responses and aggravated tumor growth in a coinjection tumor model. Mechanically, CCRL2 interacts with TLR4 on the cell surface to retain membrane TLR4 expression and further enhance its downstream Myd88-NF-κB inflammatory signaling in macrophages. Similarly, Tlr4-/- mice exhibit reduced CCRL2 expression in TAM and accelerated melanoma growth. Collectively, our study reveals a functional role of CCRL2 in activating immunostimulatory macrophages, thereby potentiating antitumor T-cell response and tumor rejection, and suggests CCLR2 as a potential biomarker candidate and therapeutic target for cancer immunotherapy.

[Integrin activation, focal adhesion maturation and tumor metastasis].

Integrins are a large family of heterodimeric cell adhesion molecules composed of α and ß subunits. Through interaction with their specific ligands, integrins mediate cell-cell and cell-extracellular matrix interactions. Via outside-in signaling, integrins can recruit cytoplasmic proteins to their intracellular domains and then cluster into supramolecular structures and trigger downstream signaling. Integrin activation is associated with a global conformation rearrangement from bent to extended in ectodomains and the separation of α and ß subunit cytoplasmic domains. During cell migration, integrins regulate the focal adhesion dynamics and transmit forces between the extracellular matrix and the cell cytoskeleton. In tumor microenvironment, integrins on multiple kinds of cells could be activated, which modulates cell migration into tumor and contributes to angiogenesis and tumor metastasis. Here, we review the mechanism of integrin activation, dynamics of focal adhesions during cell migration and tumor metastasis.

Specific gut microbiome signature predicts the early-stage lung cancer.

Alterations of gut microbiota have been implicated in multiple diseases including cancer. However, the gut microbiota spectrum in lung cancer remains largely unknown. Here we profiled the gut microbiota composition in a discovery cohort containing 42 early-stage lung cancer patients and 65 healthy individuals through the 16S ribosomal RNA (rRNA) gene sequencing analysis. We found that lung cancer patients displayed a significant shift of microbiota composition in contrast to the healthy populations. To identify the optimal microbiota signature for noninvasive diagnosis purpose, we took advantage of Support-Vector Machine (SVM) and found that the predictive model with 13 operational taxonomic unit (OTU)-based biomarkers achieved a high accuracy in lung cancer prediction (area under curve, AUC = 97.6%). This signature performed reasonably well in the validation cohort (AUC = 76.4%), which contained 34 lung cancer patients and 40 healthy individuals. To facilitate potential clinical practice, we further constructed a 'patient discrimination index' (PDI), which largely retained the prediction efficiency in both the discovery cohort (AUC = 92.4%) and the validation cohort (AUC = 67.7%). Together, our study uncovered the microbiota spectrum of lung cancer patients and established the specific gut microbial signature for the potential prediction of the early-stage lung cancer.

Regulation of immune cell trafficking by febrile temperatures.

Fever is a complex physiological response to pathogen infection and injury. One of the beneficial effects of febrile temperatures is stimulation of immune cell trafficking to the lymphoid organs and inflamed tissues, thereby enhancing immune surveillance during infection and inflammation. This trafficking process consists of a highly ordered adhesion cascade that includes tethering and rolling of immune cells along the vessel walls, chemokine-induced activation, firm arrest and diapedesis. In this review, we summarize the current findings of how febrile temperatures regulate the immune cell trafficking process. Febrile temperatures play multiple roles in the functional regulation of critical biomolecules involved in each step of the ordered adhesion cascade that includes L-selectin, chemokines, and α4 and ß2 integrins. A better understanding of febrile temperature-induced regulation of immune cell trafficking will shed light on modulating the immunity to fight against infection and inflammation.

Protein C receptor is a therapeutic stem cell target in a distinct group of breast cancers.

Breast cancer is a heterogeneous disease. In particular, triple-negative breast cancer (TNBC) comprises various molecular subgroups with unclear identities and currently has few targeted treatment options. Our previous study identified protein C receptor (Procr) as a surface marker on mammary stem cells (MaSCs) located in the basal layer of the normal mammary gland. Given the possible connection of TNBC with basal layer stem cells, we conducted comparative analyses of Procr in breast cancers of mouse and human origin. In mouse mammary tumors, we showed that Procr+ cells are enriched for cancer stem cells (CSCs) in Wnt1 basal-like tumors, but not in Brca1 basal-like tumors or PyVT luminal tumors. In human cancers, PROCR was robustly expressed in half of TNBC cases. Experiments with patient-derived xenografts (PDXs) revealed that PROCR marks CSCs in this discrete subgroup (referred to as PROCR+ TNBC). Interfering with the function of PROCR using an inhibitory nanobody reduced the CSC numbers, arrested tumor growth and prevented rapid tumor recurrence. Our data suggest a key role of MaSC in breast tumorigenesis. Moreover, our work indicates that PROCR can be used as a biomarker to stratify TNBC into clinically relevant subgroups and may provide a novel targeted treatment strategy for this clinically important tumor subtype.

Kindlin-3 Is Essential for the Resting α4ß1 Integrin-mediated Firm Cell Adhesion under Shear Flow Conditions.

Integrin-mediated rolling and firm cell adhesion are two critical steps in leukocyte trafficking. Integrin α4ß1 mediates a mixture of rolling and firm cell adhesion on vascular cell adhesion molecule-1 (VCAM-1) when in its resting state but only supports firm cell adhesion upon activation. The transition from rolling to firm cell adhesion is controlled by integrin activation. Kindlin-3 has been shown to bind to integrin ß tails and trigger integrin activation via inside-out signaling. However, the role of kindlin-3 in regulating resting α4ß1-mediated cell adhesion is not well characterized. Herein we demonstrate that kindlin-3 was required for the resting α4ß1-mediated firm cell adhesion but not rolling adhesion. Knockdown of kindlin-3 significantly decreased the binding of kindlin-3 to ß1 and down-regulated the binding affinity of the resting α4ß1 to soluble VCAM-1. Notably, it converted the resting α4ß1-mediated firm cell adhesion to rolling adhesion on VCAM-1 substrates, increased cell rolling velocity, and impaired the stability of cell adhesion. By contrast, firm cell adhesion mediated by Mn(2+)-activated α4ß1 was barely affected by knockdown of kindlin-3. Structurally, lack of kindlin-3 led to a more bent conformation of the resting α4ß1. Thus, kindlin-3 plays an important role in maintaining a proper conformation of the resting α4ß1 to mediate both rolling and firm cell adhesion. Defective kindlin-3 binding to the resting α4ß1 leads to a transition from firm to rolling cell adhesion on VCAM-1, implying its potential role in regulating the transition between integrin-mediated rolling and firm cell adhesion.

Oxygen consumption and metabolic responses of freshwater crab Sinopotamon henanense to acute and sub-chronic cadmium exposure.

To explore the respiratory and metabolic responses of the freshwater crab (Sinopotamon henanense) to Cd exposure, crabs were acutely exposed to 7.14, 14.28, 28.55 mg/L Cd for 96 h and subchronically exposed to 0.71, 1.43, 2.86 mg/L for three weeks. The oxygen consumption, concentrations of oxyhemocyanin, hemolymph protein, the activities of respiratory enzymes, i.e. lactate dehydrogenase (LDH), NAD-isocitrate dehydrogenase (IDH), cytochrome c oxidase (CCO), as well as cco-1(CCO active subunit 1) and ldh mRNA expression level and adenosine triphosphate (ATP) content in crab heart were assessed. Oxygen consumption, concentration of oxyhemocyanin and oxyhemocyanin/blood protein proportion were increased during acute exposure and decreased during sub-chronic exposure. Both exposure schemes induced downregulation of cco-1 gene expression and lowered CCO activity. For acute exposure, tissue ATP level was increased, in association with increased IDH activity and decreased LDH activity, whereas subchronic exposure caused decreased IDH activity accompanied with increased ldh gene expression and LDH activity, resulting in lowered ATP level. By coupling gene expression to biochemical and physiological endpoints, this work provides new insights into the mechanisms involved in metal stress and the differential respiratory and metabolic responses of S. henanense to acute and subchronic Cd exposure.