Cancer Letters 451 (2019) 150–155 Contents lists available at ScienceDirect Cancer Letters journal homepage: www.elsevier.com/locate/canlet Mini-review Card9 as a critical regulator of tumor development T ∗ Xiaoming Zhongb,1, Bin Chenc,1, Liang Yangd, Zhiwen Yanga, a Department of Pharmacy, Songjiang Hospital Affiliated Shanghai First People's Hospital, Shanghai Jiao Tong University, Shanghai, China b Jiangxi Province Tumor Hospital, Nanchang, China c Surgery Department, First Affiliated Hospital of Gannan Medical University, Gannan Medical University, Ganzhou, China d Nanjing Medical University, The Affiliated Changzhou No.2 People's Hospital, Nanjing Medical University, Nanjing, China ARTICLE INFO ABSTRACT Keywords: Caspase recruitment domain-containing protein 9 (Card9) is a myeloid cell-specific signaling protein that plays a Card9 critical role in NF-κB and MAPK activation. This leads to initiation of the inflammatory cytokine cascade, and Macrophages elicits the host immune response against microbial invasion, especially in fungal infection. Current research Tumor growth indicates that Card9 plays an important role in tumor progression. Here, we review the data from preclinical and Target therapy clinical studies of Card9 and suggest the potential for Card9-targeted interventions in the prevention or treat- ment of certain tumors. 1. Introduction humans. Among the various etiological factors, hepatitis C virus (HCV) infection is a major cause of HCC [11]. It is of great value for under- Caspase recruitment domain-containing protein 9 (Card9) is a cen- standing the HCC progression in HCV-infected patients. tral integrator of innate and adaptive immunity that is mainly expressed Zekri and colleagues studied 130 patients with HCV-associated liver in myeloid cells, especially in macrophages and dendritic cells. Card9 disease, 40 of which were diagnosed with HCV-associated HCC [12]. To has been identified as the downstream effector molecule of the pattern address the role of Card9 in HCC patients, Card9 mRNA in the liver was recognition receptors in myeloid cells. Following receptor engagement, quantitatively estimated by RT-PCR. The expression levels of Card9 Card9, as an intracellular adaptor molecule, can activate the NF-κB mRNA in HCV-related HCC were significantly higher than those in the and/or MAPK signaling pathways, leading to an inflammatory cascade other three groups of HCC, i.e., caused by chronic HCV, chronic active against invasive bacteria, fungi and viruses [1–6]. Thereby, Card9,an hepatitis, and liver cirrhosis. The best cutoff for Card9, a statistical inflammation-related gene, has been extensively studied in terms of its indicator that can successfully differentiate between HCC and non-HCC, potential involvement in infectious inflammatory diseases. was 47 with 80.0% sensitivity, 80.0% specificity, a 85.7% negative Understanding the factors that contribute to the initiation of cancer predictive value and a 61% positive predictive value. Therefore, Card9 development will be crucial in fighting cancer [7,8]. Recently, in- mRNA could serve as a useful clinical marker for prediction of HCC in creasing evidence has emerged that Card9 may play an important role HCV-infected patients. in multiple aspects of cancer biology [9,10]. In this review, we sum- marize the clinical data concerning Card9 expression and outcomes in 2.2. Intestinal carcinoma tumor patients, discuss the profound influence of Card9 signaling throughout each step of carcinogenesis, and highlight the potential Intestinal carcinoma, one of the most prevalent cancers, is the utility in manipulating Card9 signaling for tumor suppression. fourth leading cause of cancer death worldwide [13]. To date, the molecular mechanisms underlying cancer growth, invasion and me- 2. Clinical significance of Card9 in tumor patients tastasis for intestinal carcinoma remain unknown. A recent study conducted by Yang et al. indicated a strong clinical 2.1. Hepatocellular carcinoma correlation between Card9 expression and human colon carcinoma [9]. First, the expression levels of Card9 mRNA and protein were assessed in Hepatocellular carcinoma (HCC) is one of the most lethal cancers in colon carcinoma patients, showing high expression in tumor tissues ∗ Corresponding author. Songjiang Hospital Affiliated the First People's Hospital, Shanghai Jiao Tong University, Shanghai, 201600, China. E-mail address: [email protected] (Z. Yang). 1 These authors contributed equally to this work. https://doi.org/10.1016/j.canlet.2019.03.001 Received 31 August 2018; Received in revised form 18 February 2019; Accepted 1 March 2019 0304-3835/ © 2019 Elsevier B.V. All rights reserved. X. Zhong, et al. Cancer Letters 451 (2019) 150–155 Fig. 1. Card9 cellular distribution in intestinal car- cinoma. Card9 expression in carcinoma tissues was primarily located in tumor-infiltrating macrophages, not in cancer cells. A: Monocytes from blood vessels were released into tissues; B: Low infiltration of TAMs expressing Card9 into tumor tissues; C: High infiltration of TAMs expressing Card9 into tumor tissues. compared with normal tissues. Second, the clinicopathologic analysis of and DLBCL (positive rates 46% vs. 67%, P > 0.05). However, a higher 48 cases indicated that Card9 expression was negatively correlated with positive frequency of Card9 mRNA was detected in H. pylori-negative tumor differentiation and positively correlated with tumor invasion patients than in H. pylori-positive patients. These findings suggested depth and metastasis, further supporting its potential to foster tumor that Card9 was associated with primary gastric lymphoma, especially in metastasis. Third, immunohistochemical staining demonstrated that H. pylori-negative patients [17]. In the second study, a total of 26 pa- increased Card9 expression in colon carcinoma tissues was primarily tients who suffered from gastric MALT lymphoma with or without t(11; located in tumor-infiltrating macrophages and not in cancer cells 18) (q21; q21) were included. Discrete recurrent chromosomal gains at (Fig. 1). The same distribution of Card9 was observed in metastatic locus 9q34 (Card9) were found to be a common feature in t(11; 18)- lymph nodes from patients. These findings suggested that progression negative gastric MALT lymphoma, but rarely observed in those positive and metastasis of human colon carcinoma may be attributed to aberrant for this chromosomal translocation. It was therefore concluded that Card9 expression in macrophages. Card9 contributes to the pathogenesis of t(11; 18)-negative MALT Enteropathy-associated T-cell lymphoma (EATL) is a rare primary T- lymphoma [18]. cell lymphoma in the human small intestines. In this study, Card9 was identified as a potential candidate gene for EATL using a high-resolu- 2.4. Kidney carcinoma tion oligonucleotide microarray, and was subsequently validated in 20 patients by fluorescence in situ hybridization. The genomic profile Clear cell renal cell carcinoma (ccRCC) is the most common type of showed that recurrent copy number gains were found at 9q34.13 kidney cancer, responsible for approximately 80% of all renal neo- (Card9). Of note, compared with the other genetic abnormalities in plasms [19]. Recently, Tan and co-workers identified Card9 as a po- EATL patients, the gain at locus 9q34 (Card9) was the most frequent tential biomarker for ccRCC risk and clinical outcomes. Card9 expres- copy number change (15/20 patients, 75% frequency) [14]. Finally, sion variation between tumor and adjacent normal tissues was detected this study reported a similar frequency of copy number gain at locus in the two populations with ccRCC, the 93 patients in the screened 9q34 between Japanese and European EATL cases, irrespective of East population and the 258 patients in the validated population. After and West ethnic differences [15]. careful analysis of the clinical outcomes in the 258 patients in the va- lidation population, Card9 overexpression was found to be detrimental 2.3. Gastric carcinoma to ccRCC patients, as indicated by a 2.11-fold increase in the risk of death. This was the first report of a correlation between Card9 ex- Primary gastric lymphoma is an unusually encountered cancer that pression and clinical outcomes in tumor patients [20]. originates within the stomach. Approximately 90% of patients with primary gastric lymphoma possess mucosa-associated lymphoid tissue 2.5. Malignant pleural effusion (MALT) gastric lymphoma and diffuse large B-cell lymphoma (DLBCL). MALT gastric lymphoma is often linked to infection with the Malignant pleural mesothelioma is defined as an aggressive tumor Helicobacter pylori bacterium in the gastric mucosa [16]. with a poor prognosis. In current clinical practice, there is no highly Two studies were reported that investigated the correlations be- sensitive and specific tumor biomarker for malignant pleural effusion tween Card9 mRNA expression and clinical characteristics in patients [21]. In this study, a total of 143 patient samples, including 83 cases of with gastric carcinoma [17,18]. In the first study, 65 patients were malignant pleural effusion and 60 cases of benign pleural effusion, were diagnosed with primary gastric lymphoma, of which 43 patients had collected to establish the protein profiles using matrix-assisted laser low-grade MALT lymphoma, 16 patients had DLBCL plus MALT lym- desorption/ionization time-of-flight mass spectrometry. Compared with phoma, and 6 patients had DLBCL without MALT lymphoma. The re- benign pleural effusion, Card9 (3930.9 m/z) was obviously decreased in