Discovery of potential colorectal cancer serum biomarkers through quantitative proteomics on the colonic tissue interstitial fluids from the AOM-DSS mouse model

An Updated Review on Molecular Biomarkers in Diagnosis and Therapy of Colorectal Cancer

Colorectal cancer is one of the most common cancer types worldwide. Since colorectal cancer takes time to develop, its incidence and mortality can be treated effectively if it is detected in its early stages. As a result, non-invasive or invasive biomarkers play an essential role in the early diagnosis of colorectal cancer. Many experimental studies have been carried out to assess genetic, epigenetic, or protein markers in feces, serum, and tissue. It may be possible to find biomarkers that will help with the diagnosis of colorectal cancer by identifying the genes, RNAs, and/or proteins indicative of cancer growth. Recent advancements in the molecular subtypes of colorectal cancer, DNA methylation, microRNAs, long noncoding RNAs, exosomes, and their involvement in colorectal cancer have led to the discovery of novel biomarkers. In small-scale investigations, most biomarkers appear promising. However, large-scale clinical trials are required to validate their effectiveness before routine clinical implementation. Hence, this review focuses on small-scale investigations and results of big data analysis that may provide an overview of the biomarkers for the diagnosis, therapy, and prognosis of colorectal cancer.

Sensory nerves directly promote osteoclastogenesis by secreting peptidyl-prolyl cis-trans isomerase D (Cyp40)

Given afferent functions, sensory nerves have recently been found to exert efferent effects and directly alter organ physiology. Additionally, several studies have highlighted the indirect but crucial role of sensory nerves in the regulation of the physiological function of osteoclasts. Nonetheless, evidence regarding the direct sensory nerve efferent influence on osteoclasts is lacking. In the current study, we found that high levels of efferent signals were transported directly from the sensory nerves into osteoclasts. Furthermore, sensory hypersensitivity significantly increased osteoclastic bone resorption, and sensory neurons (SNs) directly promoted osteoclastogenesis in an in vitro coculture system. Moreover, we screened a novel neuropeptide, Cyp40, using an isobaric tag for relative and absolute quantitation (iTRAQ). We observed that Cyp40 is the efferent signal from sensory nerves, and it plays a critical role in osteoclastogenesis via the aryl hydrocarbon receptor (AhR)-Ras/Raf-p-Erk-NFATc1 pathway. These findings revealed a novel mechanism regarding the influence of sensory nerves on bone regulation, i.e., a direct promoting effect on osteoclastogenesis by the secretion of Cyp40. Therefore, inhibiting Cyp40 could serve as a strategy to improve bone quality in osteoporosis and promote bone repair after bone injury.

Single-cell transcriptomic analysis of normal and pathological tissues from the same patient uncovers colon cancer progression

The aim of the present study was to elucidate the evolutionary trajectory of colon cells from normal colon mucosa, to adenoma, then to carcinoma in the same microenvironment. Normal colon, adenoma and carcinoma tissues from the same patient were analyzed by single-cell sequencing, which perfectly simulated the process of time-dependent colon cancer due to the same microenvironment. A total of 22 cell types were identified. Results suggest the presence of dominant clones of same cells including C2 goblet cell, epithelial cell subtype 1 (Epi1), enterocyte cell subset 0 (Entero0), and Entero5 in carcinoma. Epi1 and Entero0 were Co-enriched in antibacterial and IL-17 signaling, Entero5 was enriched in immune response and mucin-type O-glycan biosynthesis. We discovered new colon cancer related genes including AC007952.4, NEK8, CHRM3, ANO7, B3GNT6, NEURL1, ODC1 and KCNMA1. The function of TBC1D4, LTB, C2CD4A, AND GBP4/5 in T cells needs to be clarified. We used colon samples from the same person, which provide new information for colon cancer therapy.

Roles of Keratins in Intestine

Keratins make up a major portion of epithelial intermediate filament proteins. The widely diverse keratins are found in both the small and large intestines. The human intestine mainly expresses keratins 8, 18, 19, and 20. Many of the common roles of keratins are for the integrity and stability of the epithelial cells. The keratins also protect the cells and tissue from stress and are biomarkers for some diseases in the organs. Although an increasing number of studies have been performed regarding keratins, the roles of keratin in the intestine have not yet been fully understood. This review focuses on discussing the roles of keratins in the intestine. Diverse studies utilizing mouse models and samples from patients with intestinal diseases in the search for the association of keratin in intestinal diseases have been summarized.

Proteomic analysis of MSC-derived apoptotic vesicles identifies Fas inheritance to ameliorate haemophilia a via activating platelet functions

Apoptotic vesicles (apoVs) are apoptotic cell-derived nanosized vesicles that play a crucial role in multiple pathophysiological settings. However, their detailed characteristics, specific surface markers, and biological properties are not fully elucidated. In this study, we compared mesenchymal stem cell (MSC)-derived apoVs and exosomes from three different types of MSCs including human bone marrow MSCs (hBMSCs), human adipose MSCs (hASCs), and mouse bone marrow MSCs (mBMSCs). We established a unique protein map of MSC-derived apoVs and identified the differences between apoVs and exosomes in terms of functional protein cargo and surface markers. Furthermore, we identified 13 proteins specifically enriched in apoVs compared to exosomes, which can be used as apoV-specific biomarkers. In addition, we showed that apoVs inherited apoptotic imprints such as Fas to ameliorate haemophilia A in factor VIII knockout mice via binding to the platelets' FasL to activate platelet functions, and therefore rescuing the blood clotting disorder. In summary, we systemically characterized MSC-derived apoVs and identified their therapeutic role in haemophilia A treatment through a previously unknown Fas/FasL linkage mechanism.

Proteomic analysis of a plastid gene encoding RPS4 mutant in Chinese cabbage (Brassica campestris L. ssp. pekinensis)

Plastids are important plant cell organelles containing a genome and bacterial-type 70S ribosomes-primarily composed of plastid ribosomal proteins and ribosomal RNAs. In this study, a chlorophyll-deficient mutant (cdm) obtained from double-haploid Chinese cabbage 'FT' was identified as a plastome mutant with an A-to-C base substitution in the plastid gene encoding the ribosomal protein RPS4. To further elucidate the function and regulatory mechanisms of RPS4, a comparative proteomic analysis was conducted between cdm and its wild-type 'FT' plants by isobaric tags and a relative and absolute quantitation (iTRAQ)-based strategy. A total of 6,245 proteins were identified, 540 of which were differentially abundant proteins (DAPs) in the leaves of cdm as compared to those of 'FT'-including 233 upregulated and 307 downregulated proteins. Upregulated DAPs were mainly involved in translation, organonitrogen compound biosynthetic process, ribosomes, and spliceosomes. Meanwhile, downregulated DAPs were mainly involved in photosynthesis, photosynthetic reaction centres, photosynthetic light harvesting, carbon fixation, and chlorophyll binding. These results indicated an important role of RPS4 in the regulation of growth and development of Chinese cabbage, possibly by regulating plastid translation activity by affecting the expression of specific photosynthesis- and cold stress-related proteins. Moreover, a multiple reaction monitoring (MRM) test and quantitative real-time polymerase chain reaction analysis confirmed our iTRAQ results. Quantitative proteomic analysis allowed us to confirm diverse changes in the metabolic pathways between cdm and 'FT' plants. This work provides new insights into the regulation of chlorophyll biosynthesis and photosynthesis in Chinese cabbage.

Beyond liquid biopsy: Toward non-invasive assays for distanced cancer diagnostics in pandemics

Liquid biopsy technologies have seen a significant improvement in the last decade, offering the possibility of reliable analysis and diagnosis from several biological fluids. The use of these technologies can overcome the limits of standard clinical methods, related to invasiveness and poor patient compliance. Along with this there are now mature examples of lab-on-chips (LOC) which are available and could be an emerging and breakthrough technology for the present and near-future clinical demands that provide sample treatment, reagent addition and analysis in a sample-in/answer-out approach. The possibility of combining non-invasive liquid biopsy and LOC technologies could greatly assist in the current need for minimizing exposure and transmission risks. The recent and ongoing pandemic outbreak of SARS-CoV-2, indeed, has heavily influenced all aspects of life worldwide. Ordinary tasks have been forced to switch from “in presence” to “distanced”, limiting the possibilities for a large number of activities in all fields of life outside of the home. Unfortunately, one of the settings in which physical distancing has assumed noteworthy consequences is the screening, diagnosis and follow-up of diseases.

In this review, we analyse biological fluids that are easily collected without the intervention of specialized personnel and the possibility that they may be used -or not-for innovative diagnostic assays. We consider their advantages and limitations, mainly due to stability and storage and their integration into Point-of-Care diagnostics, demonstrating that technologies in some cases are mature enough to meet current clinical needs.

LRG1 Mitigates Renal Interstitial Fibrosis through Alleviating Capillary Rarefaction and Inhibiting Inflammatory and Pro-Fibrotic Cytokines

INTRODUCTION

Increasing evidence has demonstrated that loss of peritubular capillaries plays a critical role in renal interstitial fibrosis. Leucine-rich α2-glycoprotein-1 (LRG1) has been observed promoting angiogenesis in the ocular disease mouse model and myocardial infarction model. We aimed to explore the role of LRG1 in renal interstitial fibrosis.

METHODS

We analyzed the expression of LRG1 in the plasma and kidney of CKD patients by ELISA and immunohistochemistry. Relationships between the expression of LRG1 in plasma and kidney and renal fibrosis and inflammation were analyzed. Tube formation assay was used to detect the angiogenesis in the human umbilical vein endothelial cell lines (HUVECs). And real-time PCR was used to detect the mRNA expression of LRG1, inflammatory factors, renal tubular injury indicators, pro-fibrotic cytokines, and CD31. We examined the effects of genetic ablation of LRG1 on renal fibrosis induced by unilateral ureteral obstruction (UUO) mice model at day 7.

RESULTS

We demonstrated that the expression of LRG1 in renal tissues and plasma samples was upregulated in CKD patients. And the expression of LRG1 was elevated in human renal tubular epithelial cell line (HK-2) cells in response to the stimulation of TNF-α in vitro, and in kidney after UUO in vivo. The deficiency of the LRG1 gene aggravated renal fibrosis, inflammatory cells infiltration, and capillary rarefaction after UUO. In vitro, LRG1 promoted the tube formation of HUVEC cells. LRG1 inhibits fibronectin secretion induced by TGF-β1 in HK-2 and overexpression of LRG1 in HK-2 cells decreased fibronectin secretion.

CONCLUSION

LRG1 may prevent renal fibrosis by inhibiting the secretion of inflammatory and pro-fibrotic cytokines and promoting angiogenesis.

Effects of combined treatment with Indomethacin and Juglone on AOM/DSS induced colon carcinogenesis in Balb/c mice: Roles of inflammation and apoptosis

AIM

Indomethacin [IND] is reported to treat colon cancer. However, continuous exposure to IND causes gastric ulceration, an adverse side effect in humans. This study implies the therapeutic effect of IND and juglone [JUG] against colon carcinogenesis, without gastric ulceration - an adverse side effect of IND.

MATERIALS AND METHODS

Adult male Balb/C mice were divided into six groups randomly: control, AOM/DSS-induced, IND-treated, JUG-treated, IND + JUG-treated and drug-control. Levels of serum markers, haematoxylin & eosin staining to observe tissue architecture, toluidine blue staining to detect mast cells expression, Masson's trichrome and sirius-red staining were used to detect the collagen deposition. RT-PCR and western blot analysis were carried out to detect inflammation and apoptosis.

KEY FINDINGS

IND + JUG effectively decreased the levels of serum markers: CEA, AFP, LDH, AST and ALT. Although, IND restored colonic architecture by regulating the accumulation of mast cell and collagen content, it causes gastric ulceration. To address this adverse effect of IND, JUG was given along with IND and was shown to alleviate IND-induced gastric ulceration. AOM/DSS induced animals showed increased expression of inflammatory molecules - TNFα, NFκB and Cox-2, apoptosis regulator - Bcl-2 and decreased expression of pro-apoptotic molecules - Bad, Bax and caspase3; whereas, IND and JUG treated groups showed decreased inflammatory expression with increased expression of pro-apoptotic molecules.

SIGNIFICANCE

IND and JUG reduce the inflammatory activity and induce apoptotic cell death, while JUG effectively prevents IND induced gastric ulceration. These findings establish that a combination of IND + JUG may serve as a promising treatment regimen for colon cancer.

Secretome Proteomic Approaches for Biomarker Discovery: An Update on Colorectal Cancer

Searching for new cancer-related biomarkers is a key priority for the early detection of solid tumors, such as colorectal cancer (CRC), in clinically relevant biological fluids. The cell line and/or tumor tissue secretome represents a valuable resource for discovering novel protein markers secreted by cancer cells. The advantage of a secretome analysis is the reduction of the large dynamic range characterizing human plasma/serum, and the simultaneous enrichment of low abundance cancer-secreted proteins, thereby overcoming the technical limitations underlying the direct search in blood samples. In this review, we provided a comprehensive overview of recent studies on the CRC secretome for biomarker discovery, focusing both on methodological and technical aspects of secretome proteomic approaches and on biomarker-independent validation in CRC patient samples (blood and tissues). Secretome proteomics are mainly based on LC-MS/MS analyses for which secretome samples are either in-gel or in-solution trypsin-digested. Adequate numbers of biological and technical replicates are required to ensure high reproducibility and robustness of the secretome studies. Moreover, another major challenge is the accuracy of proteomic quantitative analysis performed by label-free or labeling methods. The analysis of differentially expressed proteins in the CRC secretome by using bioinformatic tools allowed the identification of potential biomarkers for early CRC detection. In this scenario, this review may help to follow-up the recent secretome studies in order to select promising circulating biomarkers to be validated in larger screenings, thereby contributing toward a complete translation in clinical practice.

Challenges and Opportunities in Clinical Applications of Blood-Based Proteomics in Cancer

Simple Summary

The traditional approach in identifying cancer related protein biomarkers has focused on evaluation of a single peptide/protein in tissue or circulation. At best, this approach has had limited success for clinical applications, since multiple pathological tumor pathways may be involved during initiation or progression of cancer which diminishes the significance of a single candidate protein/peptide. Emerging sensitive proteomic based technologies like liquid chromatography mass spectrometry (LC-MS)-based quantitative proteomics can provide a platform for evaluating serial serum or plasma samples to interrogate secreted products of tumor–host interactions, thereby revealing a more “complete” repertoire of biological variables encompassing heterogeneous tumor biology. However, several challenges need to be met for successful application of serum/plasma based proteomics. These include uniform pre-analyte processing of specimens, sensitive and specific proteomic analytical platforms and adequate attention to study design during discovery phase followed by validation of discovery-level signatures for prognostic, predictive, and diagnostic cancer biomarker applications.

Abstract

Blood is a readily accessible biofluid containing a plethora of important proteins, nucleic acids, and metabolites that can be used as clinical diagnostic tools in diseases, including cancer. Like the on-going efforts for cancer biomarker discovery using the liquid biopsy detection of circulating cell-free and cell-based tumor nucleic acids, the circulatory proteome has been underexplored for clinical cancer biomarker applications. A comprehensive proteome analysis of human serum/plasma with high-quality data and compelling interpretation can potentially provide opportunities for understanding disease mechanisms, although several challenges will have to be met. Serum/plasma proteome biomarkers are present in very low abundance, and there is high complexity involved due to the heterogeneity of cancers, for which there is a compelling need to develop sensitive and specific proteomic technologies and analytical platforms. To date, liquid chromatography mass spectrometry (LC-MS)-based quantitative proteomics has been a dominant analytical workflow to discover new potential cancer biomarkers in serum/plasma. This review will summarize the opportunities of serum proteomics for clinical applications; the challenges in the discovery of novel biomarkers in serum/plasma; and current proteomic strategies in cancer research for the application of serum/plasma proteomics for clinical prognostic, predictive, and diagnostic applications, as well as for monitoring minimal residual disease after treatments. We will highlight some of the recent advances in MS-based proteomics technologies with appropriate sample collection, processing uniformity, study design, and data analysis, focusing on how these integrated workflows can identify novel potential cancer biomarkers for clinical applications.

iTRAQ-based pharmacoproteomics reveals potential targets of berberine, a promising therapy for ulcerative colitis

Previous studies by us and others have indicated that berberine is a promising therapy for ulcerative colitis (UC). However, the mechanisms of UC and the therapeutic targets of berberine are poorly understood. iTRAQ-based proteomics was utilized to characterize the proteins and pathways associated with the development of colitis and its improvement after berberine treatment. By using a modified dextran sodium sulfate (DSS) colitis as the UC model, confirmed that berberine significantly attenuated clinical symptoms and colon shorting of the colitis mice. Proteomics identified 140 and 391 proteins that were differentially expressed in the colons of DSS- or DSS plus berberine-treated mice, respectively. Subsequent verification of 15 selected differentially expressed proteins (DEPs) by multiple reaction monitoring confirmed the reliability of the iTRAQ data. Further comparisons and bioinformatics analysis demonstrated that among the identified DEPs, 26, including Hist2h2be, Tubb3, and five immunoglobulins, were oppositely regulated by DSS and DSS plus berberine treatments. In addition, five commonly dysregulated pathways, including natural killer cell-mediated cytotoxicity and RRAR signaling were identified. Network analysis revealed that proteins involved in 7 and 11 pathways in DSS and DSS plus berberine treated mice, respectively, engaged in protein-protein interactions. Our study provides the first pharmacoproteomics profiling of colitis and its recovery after berberine treatment. The proteins, pathways and networks identified provide novel insights into the pathogenesis of colitis and the action mechanism of berberine, demonstrating their values for validation in human UC which could serve as targets for the development of novel therapies for UC.

Transcriptomic and proteomic analyses of mulberry (Morus atropurpurea) fruit response to Ciboria carunculoides

The aim of this work was to gain insights into the molecular mechanisms and dynamics of the mulberry (Morus atropurpurea) fruit response to Ciboria carunculoides infection. A transcriptomic and proteomic study was carried out based on RNA sequencing and isobaric tags for relative and absolute quantification analysis, respectively. These data were then validated using quantitative real-time PCR and multiple reaction monitoring assays. Comparative analyses revealed that 9.0% of the transcriptome and 20.8% of the proteome were differentially regulated after C. carunculoides infection at the early stage (stage 1) and middle stage (stage 2), but correlation analysis revealed that only 145 genes were differentially regulated at both the transcriptome and proteome levels. The combined transcriptome and proteome analysis showed that plant hormone signal transduction, calcium-mediated defense signaling, transcription factors, and secondary metabolites were stimulated, whereas photosynthesis and cellular growth-related metabolism were suppressed after C. carunculoides infection. These finding provide theoretical foundation for disease resistance breeding of C. carunculoides. BIOLOGICAL SIGNIFICANCE: Ciboria carunculoides is a major fungal pathogen that infects mulberry fruit, leading to extensive damage and productivity loss. Despite this major impact, the mulberry fruit response to C. carunculoides infection has yet to be characterized. This study provides the first system-wide datasets with which to examine changes in the transcriptome and proteome after C. carunculoides infection in mulberry fruit. The results showed that plant hormone signal transduction, calcium-mediated defense signaling, and other pathways were stimulated, whereas photosynthesis and cellular growth-related metabolism were suppressed by C. carunculoides. These results will lead to a better understanding of the molecular mechanisms triggered in mulberry fruit in response to C. carunculoides infection and will provide new molecular targets for regulating defense responses to fungal pathogens in berry fruits.

Probing the colorectal cancer proteome for biomarkers: Current status and perspectives

Colorectal cancer (CRC) is one of the most prevalent malignancies worldwide. Biomarkers that can facilitate better clinical management of CRC are in high demand to improve patient outcome and to reduce mortality. In this regard, proteomic analysis holds a promising prospect in the hunt of novel biomarkers for CRC and in understanding the mechanisms underlying tumorigenesis. This review aims to provide an overview of the current progress of proteomic research, focusing on discovery and validation of diagnostic biomarkers for CRC. We will summarize the contributions of proteomic strategies to recent discoveries of protein biomarkers for CRC and also briefly discuss the potential and challenges of different proteomic approaches in biomarker discovery and translational applications.

Innovative methods for biomarker discovery in the evaluation and development of cancer precision therapies

The discovery of biomarkers able to detect cancer at an early stage, to evaluate its aggressiveness, and to predict the response to therapy remains a major challenge in clinical oncology and precision medicine. In this review, we summarize recent achievements in the discovery and development of cancer biomarkers. We also highlight emerging innovative methods in biomarker discovery and provide insights into the challenges faced in their evaluation and validation.

The levels of serine proteases in colon tissue interstitial fluid and serum serve as an indicator of colorectal cancer progression

The proteins in tissue interstitial fluids (TIFs) can spread into the blood and have been proposed as an ideal material to find blood biomarkers. The colon TIFs were collected from 8-, 13-, 18-, and 22-week Apc^Min/+, a typical mouse model of colorectal cancer (CRC), and wild-type mice. iTRAQ-based quantification proteomics was conducted to survey the TIF proteins whose abundance appeared to depend on tumor progression. A total of 46 proteins that exhibited consecutive changes in abundance were identified, including six serine proteases, chymotrypsin-like elastase 1 (CELA1), chymotrypsin-like elastase 2A (CEL2A), chymopasin, chymotrypsinogen B (CTRB1), trypsin 2 (TRY2), and trypsin 4 (TRY4). The observed increases in the abundance of serine proteases were supported in another quantitative evaluation of the individual colon TIFs using a multiple reaction monitor (MRM) assay. Importantly, the increases in the abundance of serine proteases were also verified in the corresponding sera. The quantitative verification of the serine proteases was further extended to the clinical sera, revealing significantly higher levels of CELA1, CEL2A, CTRL/chymopasin, and TRY2 in CRC patients. The receiver operating characteristic analysis illustrated that the combination of CELA1 and CTRL reached the best diagnostic performance, with 90.0% sensitivity and 80.0% specificity. Thus, the quantitative target analysis demonstrated that some serine proteases are indicative of CRC progression.

Cell Line Secretome and Tumor Tissue Proteome Markers for Early Detection of Colorectal Cancer: A Systematic Review

Objective: In order to find low abundant proteins secretome and tumor tissue proteome data have been explored in the last few years for the diagnosis of colorectal cancer (CRC). In this review we aim to summarize the results of studies evaluating markers derived from the secretome and tumor proteome for blood based detection of colorectal cancer. Methods: Observing the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines PubMed and Web of Science databases were searched systematically for relevant studies published up to 18 July 2017. After screening for predefined eligibility criteria a total of 47 studies were identified. Information on diagnostic performance indicators, methodological procedures and validation was extracted. Functions of proteins were identified from the UniProt database and the the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool was used to assess study quality. Results: Forty seven studies meeting inclusion criteria were identified. Overall, 83 different proteins were identified, with carcinoembryonic Antigen (CEA) being by far the most commonly reported (reported in 24 studies). Evaluation of the markers or marker combinations in blood samples from CRC cases and controls yielded apparently very promising diagnostic performances, with area under the curve >0.9 in several cases, but lack of internal or external validation, overoptimism due to overfitting and spectrum bias due to evaluation in clinical setting rather than screening settings are major concerns. Conclusions: Secretome and tumor proteome-based biomarkers when validated in blood yield promising candidates. However, for discovered protein markers to be clinically applicable as screening tool they have to be specific for early stages and need to be validated externally in larger studies with participants recruited in true screening setting.

Mass spectrometry-assisted gel-based proteomics in cancer biomarker discovery: approaches and application

There is a critical need for the discovery of novel biomarkers for early detection and targeted therapy of cancer, a major cause of deaths worldwide. In this respect, proteomic technologies, such as mass spectrometry (MS), enable the identification of pathologically significant proteins in various types of samples. MS is capable of high-throughput profiling of complex biological samples including blood, tissues, urine, milk, and cells. MS-assisted proteomics has contributed to the development of cancer biomarkers that may form the foundation for new clinical tests. It can also aid in elucidating the molecular mechanisms underlying cancer. In this review, we discuss MS principles and instrumentation as well as approaches in MS-based proteomics, which have been employed in the development of potential biomarkers. Furthermore, the challenges in validation of MS biomarkers for their use in clinical practice are also reviewed.

Unphosphorylated STAT1 represses apoptosis in macrophages during Mycobacteriumtuberculosis infection

In murine macrophages infected with Mycobacterium tuberculosis (Mtb), the level of phosphorylated STAT1 (P-STAT1), which drives the expression of many pro-apoptosis genes, increases quickly but then declines over a period of hours. By contrast, infection induces a continued increase in the level of unphosphorylated STAT1 that persists for several days. Here, we found that the level of unphosphorylated STAT1 correlated with the intracellular bacterial burden during the later stages of infection. To investigate the significance of a high level of unphosphorylated STAT1, we increased its concentration exogenously, and found that the apoptosis rate induced by Mtb was sufficiently decreased. Further experiments confirmed that unphosphorylated STAT1 affects the expression of several immune-associated genes and lessens the sensitivity of macrophages to CD95 (FAS)-mediated apoptosis during Mtb infection. Furthermore, we characterized 149 proteins that interacted with unphosphorylated STAT1 and the interactome network. The cooperation between unphosphorylated STAT1 and STAT3 results in downregulation of CD95 expression. Additionally, we verified that unphosphorylated STAT1 and IFIT1 competed for binding to eEF1A. Taken together, our data show that the role of unphosphorylated STAT1 differs from that of P-STAT1, and represses apoptosis in macrophages to promote immune evasion during Mtb infection.