Serum YKL-40 level is associated with the chemotherapy response and prognosis of patients with small cell lung cancer

Significance of chitinase-3-like protein 1 in the pathogenesis of inflammatory diseases and cancer

Chitinase-3-like protein 1 (CHI3L1) is a secreted glycoprotein that mediates inflammation, macrophage polarization, apoptosis, and carcinogenesis. The expression of CHI3L1 is strongly upregulated by various inflammatory and immunological diseases, including several cancers, Alzheimer's disease, and atherosclerosis. Several studies have shown that CHI3L1 can be considered as a marker of disease diagnosis, prognosis, disease activity, and severity. In addition, the proinflammatory action of CHI3L1 may be mediated via responses to various proinflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, interleukin-6, and interferon-γ. Therefore, CHI3L1 may contribute to a vast array of inflammatory diseases. However, its pathophysiological and pharmacological roles in the development of inflammatory diseases remain unclear. In this article, we review recent findings regarding the roles of CHI3L1 in the development of inflammatory diseases and suggest therapeutic approaches that target CHI3L1.

A Natural CHI3L1-Targeting Compound, Ebractenoid F, Inhibits Lung Cancer Cell Growth and Migration and Induces Apoptosis by Blocking CHI3L1/AKT Signals

Our previous big data analyses reported a strong association between CHI3L1 expression and lung tumor development. In this present study, we investigated whether a CHI3L1-inhibiting natural compound, ebractenoid F, inhibits lung cancer cell growth and migration and induces apoptosis. Ebractenoid F concentration-dependently (0, 17, 35, 70 µM) and significantly inhibited the proliferation and migration of A549 and H460 lung cancer cells and induced apoptosis. In the mechanism study, we found that ebractenoid F bound to CHI3L1 and suppressed CHI3L1-associated AKT signaling. Combined treatment with an AKT inhibitor, LY294002, and ebractenoid F synergistically decreased the expression of CHI3L1. Moreover, the combination treatment further inhibited the growth and migration of lung cancer cells and further induced apoptosis, as well as the expression levels of apoptosis-related proteins. Thus, our data demonstrate that ebractenoid F may serve as a potential anti-lung cancer compound targeting CHI3L1-associated AKT signaling.

Develop companion radiopharmaceutical YKL40 antibodies as potential theranostic agents for epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is usually diagnosed at an advanced stage and has poor prognosis. Theranostic agents are the current trend in drug development, but are lacking in EOC. YKL40 is predominantly expressed and involved in tumorigenesis in EOC. In this study, we developed a companion theranostic agent targeting YKL40. We measured YKL40 expression levels in ascites using ELISA and correlated them with the clinical outcomes of patients with EOC. We developed radionuclide labeled In-111/Lu-177-DTPA-YKL40 neutralizing antibodies and investigated their radiochemical purity, SPECT/CT imaging, bio-distribution, and therapeutic responses in ovarian cancer xenograft mice. We demonstrated that YKL40 expression levels in ascites were significantly higher in EOC patients with serous histological type, high tumor grade, advanced stage, tumor recurrence, chemoresistance, and tumor-related death. The radiochemical purity of In-111/Lu-177-DTPA-YKL40 neutralizing antibodies reached more than 90% after 24 h of labeling. SPECT/CT imaging showed significant accumulation of In-111-DTPA-YKL40 and Lu-177-DTPA-YKL40 antibodies at the tumor site of ovarian cancer xenograft mice 24 h after administration. Lu-177-DTPA-YKL40 antibodies significantly inhibited tumor growth in ovarian cancer xenograft mice. Our study indicated that In-111/Lu-177-DTPA-YKL40 neutralizing antibodies could be potential companion theranostic agents for patients with EOC.

A small molecule targeting CHI3L1 inhibits lung metastasis by blocking IL-13Rα2-mediated JNK-AP-1 signals

Our previous big data analyses showed a high level of association between chitinase 3 like1 (CHI3L1) expression and lung tumor development. In the present study, we investigated whether a CHI3L1‐inhibiting chemical, 2‐({3‐[2‐(1‐cyclohexen‐1‐yl)ethyl]‐6,7‐dimethoxy‐4‐oxo‐3,4‐dihydro‐2‐quinazolinyl}sulfanyl)‐N‐(4‐ethylphenyl)butanamide (K284), could inhibit lung metastasis and studied its mechanism of action. We investigated the antitumor effect of K284 both in vitro and in vivo. K284 (0.5 mg·kg⁻¹ body weight) significantly inhibited lung metastasis in in vivo models after injection of murine melanoma cells (B16F10) or adenocarcinomic human alveolar basal epithelial cells (A549). K284 significantly and concentration‐dependently also inhibited cancer cell proliferation and migration in the A549 and H460 lung cancer cell lines. We found that the binding of K284 to the chitin‐binding domain (CBD) of CHI3L1 prevented the binding of CHI3L1 to its receptor, interleukin‐13 receptor subunit alpha‐2 (IL‐13Rα2), thereby suppressing the CHI3L1 signal. This blocking of the CHI3L1‐IL‐13Rα2 signal caused the inhibition of c‐Jun N‐terminal kinase (JNK)‐activator protein 1 (AP‐1) signals, resulting in the prevention of lung metastasis and cancer cell growth. Our data demonstrate that K284 may serve as a potential candidate anticancer compound targeting CHI3L1.

Plasma levels of YKL-40 as a prognostic factor in childhood acute lymphoblastic leukemia

YKL-40, also known as chitinase-3-like protein 1 (CHI3L1), is an inflammatory glycoprotein secreted by different types of cells, such as inflammatory cells. The levels of this protein are elevated in the serum or plasma of patients with different types of cancer, and high concentrations are associated with poor prognosis and short survival in patients with liver, breast, lung, bladder and endometrial cancers. In Mexico, acute lymphoblastic leukemia (ALL) is the most common type of cancer affecting the pediatric population. The prognosis of patients with ALL is difficult to establish. Hence, the objective of the present study was to analyze the plasma levels of YKL-40 in Mexican children with ALL and investigate its role as a prognostic factor. A case-control study was performed in a population of 90 children aged 1-18 years, among whom 45 had ALL and 45 were hematologically healthy. The levels of YKL-40 in plasma samples were measured using ELISA and were found to be significantly higher in children with ALL compared with those in controls (P<0.0001). Children with ALL who had high plasma levels of YKL-40 (≥36.34 ng/ml) had shorter survival compared with those with low levels (<36.34 ng/ml; P<0.05). The findings of the present study revealed that the YKL-40 plasma level, age/initial leukocyte count and central nervous system invasion were associated with the prognosis of children with ALL [odds ratio (OR)=6.06, 95% confidence interval (CI): 1.1-31.6, P=0.03; OR=8.53, 95% CI: 1.2-58.2, P=0.03; and OR=6.45, 95% CI: 1.01-41.2, P=0.04, respectively]. Therefore, YKL-40 plasma levels may serve as a prognostic biomarker in pediatric patients with ALL.

Prognostic significance of serum osteopontin levels in small cell lung cancer

BACKGROUND

Osteopontin (OPN) is closely related to tumor occurrence and metastasis. This study explored the clinical value of serum OPN levels in small cell lung cancer (SCLC) patients.

METHODS

The ELISA method was used to determine the OPN level of 96 SCLC patients before and after first-line chemotherapy, and compared with 60 healthy controls.

RESULTS

The serum OPN level of SCLC patients before treatment was significantly higher than that of the healthy control (P < 0.001). Serum OPN levels were related to disease stage, tumor size, and lymph node metastasis (P = 0.012, 0.034, and 0.037, respectively). Serum OPN level decreased after first-line chemotherapy (P = 0.019), which was related to treatment response (P = 0.011). The serum OPN level was an independent predictor of overall survival.

CONCLUSIONS

The serum OPN level can be used as a biomarker to predict treatment response and survival of SCLC patients.

YKL-39 as a Potential New Target for Anti-Angiogenic Therapy in Cancer

YKL-39 belongs to the evolutionarily conserved family of Glyco_18-containing proteins composed of chitinases and chitinase-like proteins. Chitinase-like proteins (CLPs) are secreted lectins that lack hydrolytic activity due to the amino acid substitutions in their catalytic domain and combine the functions of cytokines and growth factors. One of the major cellular sources that produce CLPs in various pathologies, including cancer, are macrophages. Monocytes recruited to the tumor site and programmed by tumor cells differentiate into tumor-associated macrophages (TAMs), which are the primary source of pro-angiogenic factors. Tumor angiogenesis is a crucial process for supplying rapidly growing tumors with essential nutrients and oxygen. We recently determined that YKL-39 is produced by tumor-associated macrophages in breast cancer. YKL-39 acts as a strong chemotactic factor for monocytes and stimulates angiogenesis. Chemotherapy is a common strategy to reduce tumor size and aggressiveness before surgical intervention, but chemoresistance, resulting in the relapse of tumors, is a common clinical problem that is critical for survival in cancer patients. Accumulating evidence indicates that TAMs are essential regulators of chemoresistance. We have recently found that elevated levels of YKL-39 expression are indicative of the efficiency of the metastatic process in patients who undergo neoadjuvant chemotherapy. We suggest YKL-39 as a new target for anti-angiogenic therapy that can be combined with neoadjuvant chemotherapy to reduce chemoresistance and inhibit metastasis in breast cancer patients.

Prognostic value of YKL-40 in solid tumors: a meta-analysis of 41 cohort studies

Background

Serum/plasma YKL-40 can be a useful index that is associated with tumor development. However, the prognostic value of serum/plasma YKL-40 in patients with solid tumors is still unclear. We aimed to utilize the existing literature to investigate the prognostic value of serum/plasma YKL-40 in solid tumors.

Methods

An extensive literature search for relevant studies was conducted with the Embase, Medline and Web of Science databases. The effect on survival was measured with the hazard ratio (HR). Then, pooled HRs and 95% confidence intervals (CIs) were calculated using the random and fixed-effects models according to the heterogeneity of the included studies.

Results

This meta-analysis was based on 41 publications and comprised a total of 7762 patients with solid tumors. The pooled HR showed that elevated serum/plasma YKL-40 was significantly associated with poor OS (HR, 1.44; 95% CI 1.33–1.56). We also found that elevated serum/plasma YKL-40 had significant prognostic effects on OS in various cancer subgroups such as gastrointestinal tumors (HR, 1.37; 95% CI 1.18–1.58), ovarian cancer (HR, 2.27; 95% CI 1.69–3.06), melanoma (HR, 1.77; 95% CI 1.18–2.67), lung cancer (HR, 1.73; 95% CI 1.35–2.23), urologic neoplasms (HR, 1.61; 95% CI 1.08–2.40) and glioblastoma (HR, 1.23; 95% CI 1.07–1.42); in contrast, the prognostic effect of serum/plasma YKL-40 was not statistically significant in breast cancer (HR, 1.07; 95% CI 0.98–1.17).

Conclusions

The available evidence supports the hypothesis that elevated serum/plasma YKL-40 is associated with poor survival in patients with solid tumors and that serum/plasma YKL-40 may serve as a novel prognostic biomarker.

Tumor-Promoting Activity of Long Noncoding RNA LINC00466 in Lung Adenocarcinoma via miR-144-Regulated HOXA10 Axis

Previous investigations have implicated long noncoding RNAs in lung adenocarcinoma, which is an aggressive disease with poor prognosis and high mortality. Through the alteration of lung adenocarcinoma-related long noncoding RNA and miRNA based on microarray analysis, our aim was to understand the role of LINC00466 and miR-144 in lung adenocarcinoma progression. The relationship among LINC00466, miR-144, and HOXA10 was also verified. Moreover, to examine whether the LINC00466/miR-144/HOXA10 axis contributed to the cellular processes in lung adenocarcinoma, A549 and XWLC-05 cells were transduced with siRNA LINC00466, siRNA HOXA10, or miR-144 mimic plasmids. Highly expressed LINC00466 and HOXA10 and lowly expressed miR-144 were eventually revealed in lung adenocarcinoma tissues. HOXA10 was down-regulated in response to the overexpression of miR-144, whereas inhibition of LINC00466 decreased its binding to miR-144, thereby up-regulating miR-144, which, in turn, halted the lung adenocarcinoma progression. LINC00466 silencing or miR-144 up-regulation exerted an inhibitory role in the tumorigenicity, invasion, migration, and proliferation, and it also promoted apoptosis of lung adenocarcinoma cells. Furthermore, tumor formation was inhibited by knockdown of LINC00466 or overexpression of miR-144. Taken together, LINC00466 could restrain the miR-144 expression to up-regulate HOXA10 and, therefore, promote lung adenocarcinoma.

Serum pleiotrophin as a diagnostic and prognostic marker for small cell lung cancer

Pleiotrophin (PTN) is involved in tumour progression, angiogenesis and metastasis. The purpose of this study was to investigate the expression level of PTN in the serum of patients with small cell lung cancer (SCLC) and to explore the clinical significance of PTN. Serum samples from 128 patients with SCLC, 120 healthy volunteers (HV) and 60 patients with benign lung disease (BLD) were collected. The levels of serum PTN were determined with ELISA and its correlation with the clinical data was examined. The serum PTN levels in SCLC patients were significantly higher than that in BLD patients (P < 0.05) or HV (P < 0.05). With a cutoff value of 258.18 ng/mL, the sensitivity and specificity of PTN to SCLC patients and BLD patients, SCLC patients and HV were 79.2% and 91.7%, 86.7% and 95.8% respectively. An area under the curve for all stages of SCLC resulting from PTN, which was significantly better than the other tumour markers tested including progastrin‐releasing peptide and neuron‐specific enolase. High serum PTN levels appear to correlate with poor survival in patients with SCLC. These results suggest that PTN levels in the serum could be a new effective biomarker for the diagnosis and prognosis of SCLC.

YKL-40 in the diagnosis, prediction of prognosis, and platinum sensitivity in serous epithelial ovarian cancer

OBJECTIVE

To evaluate the use of YKL-40 in the discrimination between benign and malignant adnexal mass and to determine its prognostic value in assessing residual tumor after primary cytoreduction and platinum sensitivity in serous epithelial ovarian carcinoma (EOC).

MATERIALS AND METHODS

During the three years from January 2015 to December 2017, a nonconsecutive series of 100 patient (60 malignant, 40 benign) who underwent surgery for an adnexal mass were enrolled in the study. Preoperatively, serum samples were collected for YKL-40 level analysis.

RESULTS

YKL-40 [receiver operator characteristics (ROC)-area under curve (AUC)=0.83] was a significantly better predictor of EOC than cancer antigen-125 (ROC-AUC=0.75). Using a cut-off for YKL-40 of 47.7 ng/mL had a sensitivity of 80% and a specificity of 70%. Higher serum YKL-40 levels were associated with advanced stage, higher grade, residual tumor after primary cytoreduction and recurrence. Platinum-sensitive patients had significantly elevated levels of YKL-40 compared with platinum-resistant or refractory patients.

CONCLUSION

The results obtained from our study support the use of serum YKL-40 for the discrimination between malignant and benign ovarian tumors. YKL-40 levels in patients with serous EOC may also predict disease residual disease after primary cytoreduction and recurrence. Further studies are needed to understand the relationship between YKL-40 and platinum sensitivity.

[Detection of chitinase 3-like 1 combined with other biomarkers for diagnosis of pancreatic cancer]

OBJECTIVE

To assess the value of chitinase 3-like 1 (CHI3L1) alone or in combination with other biomarkers in the diagnosis of pancreatic cancer.

METHODS

Serum samples were collected from 70 patients with pancreatic cancer and 31 healthy subjects and the levels of CHI3L1, CA199, C3, C4, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein-cholesterol (LDL-C) in serum were detected.

RESULTS

The serum samples from pancreatic cancer patients showed significantly higher CHI3L1, CA199, C3, C4, HDL-C, and LDL-C levels than those from healthy subjects (P<0.05). In patients with pancreatic cancer, serum CHI3L1 level was significantly correlated with the administration of anti-cancer therapy (P<0.05), but not with gender, age, metastasis or other clinicopathological parameters (P<0.05). ROC curve analysis showed that serum CHI3L1, CA199, C3, C4, HDL-C, and LDL-C all had diagnostic value for pancreatic cancer. Multivariate analysis suggested that the combined detection model of CHI3L1, CA199, C3, and HDL-C (AUC=0.964) had a greater diagnostic value than CA199 (AUC=0.896) alone and the combined detection model consisting of CA199, C3, and HDL-C (AUC=0.923; P<0.05).

CONCLUSION

Serum levels of CHI3L1, CA199, C3, C4, HDL-C, and LDL-C all have diagnostic value for pancreatic cancer, and the combined model consisting of CHI3L1, CA199, C3, and HDL-C have greater diagnostic efficacy than the other biomarkers either alone or in combination.

Circulating tumor cell interactions with macrophages: implications for biology and treatment

Cancer and metastasis are closely associated with inflammation. Macrophages are important effector cells in enhancing tumor proliferation, invasion and providing protection against the immune system. Despite advanced knowledge of tumor-macrophage interactions, the role of macrophages in emergence and invasion of circulating tumor cells (CTCs) is not known. A series of six CTC cell lines have been derived from blood of patients with extensive disease small cell lung cancer (ED-SCLC) in our lab, most likely representing a homogenous cell population of the actual metastasis-initiating cells (MIC) of CTCs. SCLC has an unfavorable prognosis due to rapid dissemination and early chemoresistant relapses. SCLC CTCs recruit macrophages and elicit secretion of various cytokines and the six CTC lines express chitinase-3-like-1 (CHI3L1), vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP9) in abundance. CHI3L1 is cytokine/growth factor expressed in inflammation and cancer and found to be correlated to metastasis and a dismal prognosis. In conclusion, SCLC CTCs have acquired the essential means for aggressiveness and invasion in a tumor microenvironment specifically shaped by macrophages and inflammation.

Preoperative serum levels of YKL 40 and CA125 as a prognostic indicators in patients with endometrial cancer

OBJECTIVE

To evaluate the utility of YKL-40 and CA125 in endometrial cancer (EC) patients, and to determine their prognostic value in assessing the disease-free survival (DFS) and overall survival (OS).

METHODS

We analyzed seventy-four EC patients, treated at a single institution and 25 healthy individuals. CA 125 serum level was evaluated in the Cobas 6000 system and YKL-40, using the ELISA method.

RESULTS

Significantly increased serum level of YKL-40 and CA125 was in EC patients in FIGO I-IB when compared to healthy controls. CA125 was significantly higher in patients with more advanced FIGO stage vs. FIGO I, and also in patients with lymph node metastases vs. patients with no metastases. The obtained AUC for YKL-40 was higher than for CA125. There was, however, higher diagnostic sensitivity for YKL-40 in comparison to CA125, both in patients with type I and type II tumours. In patients who had disease progression, both the percentage of elevated concentration of CA 125 and YKL-40 was higher than in patients with remission. The Chi2 test demonstrated the statistically significant differences. The predictive value of CA125 in an aspect of DFS and OS was demonstrated.

CONCLUSIONS

A high diagnostic sensitivity of YKL-40 in the early stages of the disease suggests the possibility of using this biomarker at an early diagnostic phase of patients with EC. The patients with increased levels of YKL-40 before treatment are also at the higher risk of relapse. The determination of CA125 before surgery may be helpful in the evaluation of the regional lymph nodes, and is a poor prognostic factor for OS and DFS.

CHI3L1 overexpression is associated with metastasis and is an indicator of poor prognosis in papillary thyroid carcinoma

OBJECTIVE

In this study, we examined the relationships between the expression level of CHI3L1 and the clinicopathological characteristics of papillary thyroid carcinoma.

METHODS

A total of 322 tissue samples from patients with papillary thyroid carcinoma were collected, and the CHI3L1 expression levels in tumor tissues, matched adjacent noncancerous tissues were detected using immunohistochemistry (IHC) and qRT-PCR. The relationships between CHI3L1 expression levels and the clinical characteristics were evaluated.

RESULTS

CHI3L1 expression was significantly increased in papillary thyroid carcinoma compared with matched adjacent noncancerous tissues (P< 0.001), tumor tissues with lymph node metastasis (LNM) compared with tumor tissues without LNM (P< 0.001) and tumor tissues with distant organ metastasis (DOM) compared with tumor tissues without DOM (P< 0.01). CHI3L1 expression was significantly associated with tumor size (P= 0.0001), lymph node metastasis (P< 0.0001), distant organ metastasis (P< 0.0001), extrathyroid invasion (P= 0.0022), vascular invasion (P= 0.0004) and TNM stage (P= 0.0001). CHI3L1 overexpression in papillary thyroid carcinoma tissues correlates with the tumor malignant potential (P< 0.01). More importantly, Cox multifactor analysis indicated that patients with high CHI3L1 expression have lower overall survival, disease-free survival, lymph node recurrence-free survival, and distant recurrence free survival rates than those with low expression (P< 0.05). And our findings were further validated by online Oncomine database.

CONCLUSIONS

CHI3L1 is associated with tumor metastasis and might be a prognostic biomarker for papillary thyroid carcinoma.

Expression of YKL-40 and MIP-1a proteins in exudates and transudates: biomarkers for differential diagnosis of pleural effusions? A pilot study

Background

YKL-40 is an extracellular matrix glycoprotein with a significant role in tissue inflammation and remodeling. MIP-1a has chemotactic and pro-inflammatory properties, and is induced by YKL-40 in several lung disorders. The aim of this study was to determine the levels of YKL-40 and MIP-1a in blood serum and pleural fluids of various pulmonary diseases, and to evaluate their potential role as differential diagnosis biomarkers.

Methods

We recruited 60 patients (age: 62.5 ± 20.6 years) with pleural effusions: 49 exudates and 11 transudates (T). Exudates were further classified based on the underlying disease: ten with tuberculosis (TB), 13 with lung cancer (LCa), 15 with metastatic cancer (MCa) of non-lung origin and 11 with parapneumonic (PN) effusions. YKL-40 and MIP-1a levels were measured by ELISA.

Results

Pleural YKL-40 levels (ng/ml) were similar among all patient groups (TB: 399 ± 36, LCa: 401 ± 112, MCa: 416 ± 34, PN: 401 ± 50, T: 399 ± 42, p = 0.92). On the contrary, YKL-40 was significantly lower in the serum of TB patients (TB: 58 ± 22, LCa: 212 ± 106, MCa: 254 ± 140, PN: 265 ± 140, T: 229 ± 123, p < 0.001). Pleural MIP-1a protein levels (ng/ml) were statistically lower only in patients with LCa (TB: 25.0 ± 20.2, LCa: 7.3 ± 6.0, MCa: 16.1 ± 14.9, PN: 25.4 ± 27.9, T: 18.5 ± 7.9, p = 0.012), a finding also observed in serum MIP-1a levels (TB: 17.1 ± 7.6, LCa: 9.4 ± 7.0, MCa: 28.7 ± 28.7, PN: 33.3 ± 24.0, T: 22.9 ± 8.7, p = 0.003).

Conclusions

Our data suggest that both YKL-40 and MIP-1a, particularly in serum, could prove useful for the differentiation of pleural effusions in clinical practice, especially of TB or LCa origin. However, large-scale studies are needed to validate these findings.

The role of chitin, chitinases, and chitinase-like proteins in pediatric lung diseases

Chitin, after cellulose, the second most abundant biopolymer on earth, is a key component of insects, fungi, and house-dust mites. Lower life forms are endowed with chitinases to defend themselves against chitin-bearing pathogens. Unexpectedly, humans were also found to express chitinases as well as chitinase-like proteins that modulate immune responses. Particularly, increased levels of the chitinase-like protein YKL-40 have been associated with severe asthma, cystic fibrosis, and other inflammatory disease conditions. Here, we summarize and discuss the potential role of chitin, chitinases, and chitinase-like proteins in pediatric lung diseases.

Establishment of using serum YKL-40 and SCCA in combination for the diagnosis of patients with esophageal squamous cell carcinoma

Background

Elevated serum YKL-40 levels have been observed in various cancers. We evaluated the diagnostic performance of serum YKL-40 alone or in combination with the CEA, CYFRA21-1 and SCCA tumor markers for patients with esophageal squamous cell carcinoma (ESCC).

Methods

YKL-40 was detected in ESCC cell lines and tissues by real-time RT-PCR, Western blotting and ELISA. YKL-40 protein expression was determined in 20 ESCC tumor tissues using immunohistochemistry. Serum YKL-40 was measured by ELISA in 126 healthy donors, 59 patients with benign esophageal diseases and 150 patients with ESCC. Serum CEA, CYFRA21-1 and SCCA were determined by electrochemiluminescence.

Results

YKL-40 mRNA and protein were observed in ESCC cancer cell lines, tissues and cell culture media, respectively. YKL-40 expression was observed in 17 of 20 ESCC samples (85%). Serum YKL-40 concentration was significantly elevated in patients with ESCC (Range: 6.95-502.10 ng/ml) compared with patients with benign diseases (Range: 1.21-429.30 ng/ml; P = 0.038) and healthy controls (Range: 2.56-132.26 ng/ml; P < 0.001). ROC curves demonstrated that serum YKL-40 has a sensitivity of 72.70%, a specificity of 84.13% and an AUC of 0.874 for the diagnosis of ESCC, which was superior to CEA (Sen: 8.00%; Spe: 96.80%, AUC = 0.652), CYFRA21-1 (Sen: 40.00%; Spe: 92.06%, AUC = 0.746) and SCCA (Sen: 32.67%; Spe: 94.44%, AUC = 0.789). The YKL-40 and SCCA combination was better for diagnosing ESCC (Sen: 82.00%, Spe: 79.37%, PPV: 82.55 and NPV: 78.74; AUC = 0.917) than the YKL-40 and CEA combination (Sen: 74.00%, Spe: 83.20%, PPV: 84.09 and NPV: 72.73; AUC = 0.877), the YKL-40 and CYFRA21-1 combination (Sen: 82.00%, Spe: 77.78%, PPV: 81.46% and NPV: 78.40%; AUC = 0.897) or the CEA, CYFRA21-1 and SCCA combination (Sen: 56.67%, Spe: 84.80%, PPV: 81.73 and NPV: 61.99; AUC = 0.831). Associations between serum YKL-40 levels and the clinic characteristics of ESCC were not significant, with the exception of age (p = 0.001).

Conclusions

ESCC tumor cells and tissues express YKL-40. Serum YKL-40 may be a potential biomarker for ESCC. Serum YKL-40 in combination with SCCA significantly increases the sensitivity of detecting ESCC.