Association of Sarcopenia With Toxicity and Survival in Postoperative Recurrent Esophageal Squamous Cell Carcinoma Patients Receiving Chemoradiotherapy

Background

Sarcopenia has been associated with treatment-related toxicities and poor survival in cancer patients. Our aim was to investigate the prevalence of sarcopenia in postoperative recurrent esophageal squamous cell carcinoma (ESCC) patients receiving chemoradiotherapy (CRT) and evaluate associations with treatment-related toxicity and prognosis.

Methods

One hundred and eighty-four patients with postoperative locoregional recurrent ESCC receiving CRT between January 2014 and December 2016 were included. The skeletal muscle area (SMA) was measured at the third lumbar vertebra level. Sarcopenia was defined as skeletal muscle index (SMI = SMA/height²) less than 47.24/cm²/m² for men and 36.92/cm²/m² for women. Association of sarcopenia with overall survival (OS) was analyzed using univariate and multivariate cox regression models.

Results

Sarcopenia was observed in 94 of 184 (51.1%) patients. Sarcopenic patients had significantly higher rates of grade 3-4 toxicities compared to those without sarcopenia (36.2% vs 21.1%, p = 0.034). The survival rate at 12 and 24 months was 36.2% and 3.2% in the sarcopenic patients and 57.8% and 17.8% in the non-sarcopenic patients (p < 0.001). Multivariate cox regression analysis showed that sarcopenia was significantly associated with decreased OS (HR = 1.729, 95% CI 1.231-2.428, p = 0.002).

Conclusions

Sarcopenia is an independent indicator of poor survival in postoperative locoregional recurrent ESCC patients treated with CRT. Early nutritional interventions before treatment may improve the prognosis.

Concurrent chemoradiotherapy with S-1 compared with concurrent chemoradiotherapy with docetaxel and cisplatin for locally advanced esophageal squamous cell carcinoma

Background

This retrospective study was to assess and compare the toxicity and efficacy of concurrent chemoradiotherapy (CCRT) with S-1 or docetaxel and cisplatin in patients with locally advanced esophageal squamous cell carcinoma (ESCC).

Methods

Patients with locally advanced ESCC who received CCRT with S-1 (70 mg/m² twice daily on days 1–14, every 3 weeks for 2 cycles, S-1 group) or docetaxel (25 mg/m²) and cisplatin (25 mg/m²) on day 1 weekly (DP group) between 2014 and 2016 were retrospectively analyzed. Radiotherapy was delivered in 1.8–2.0 Gy per fraction to a total dose of 50–60 Gy. Treatment-related toxicities (Common Terminology Criteria for Adverse Events version 4.0), response rate, and survival outcomes were compared between groups.

Results

A total of 175 patients were included in this study (72 in the S-1 group and 103 in the DP group). Baseline characteristics were well balanced between the two groups. The incidence of grade 3–4 adverse events were significantly lower in the S-1 group than that of the DP group (22.2% vs. 45.6%, p = 0.002). In the DP group, elderly patients (> 60 years) had a significantly higher rate of grade 3–4 adverse events than younger patients (58.1% vs. 31.3%, p = 0.01). The objective overall response rate (complete response + partial response) was 68.1% in the S-1 group, and 73.8% the DP group (p = 0.497). The 3-year overall survival was 34.7% in the S-1 group, and 38.8% in the DP group (p = 0.422). The 3-year progression free survival in the DP group was higher than that in the S-1 group but without significant difference (33.0% vs. 25.0%, p = 0.275).

Conclusion

CCRT with S-1 is not inferior to CCRT with docetaxel and cisplatin and is better tolerated in in elderly patients with locally advanced ESCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13014-021-01821-6.

miR-206 regulates non-small-cell lung cancer cell aerobic glycolysis by targeting hexokinase 2

Aerobic glycolysis was closely associated with the malignant transformation and prognosis of tumours. miR-206 was found to be downregulated in several cancers. However, whether miR-206 functions in non-small-cell lung cancers (NSCLCs) via the process of aerobic glycolysis remains poorly characterized. Quantitative real-time PCR was performed to detect miR-206 level in NSCLC cells and tissues. The effect of miR-206 on hexokinase 2 (HK2) expression was examined through miR-206 overexpression or miR-206 knockdown. CCK-8 assay and colony formation assay were carried out to explore the role of miR-206 on cell proliferation and colony formation, respectively. The relationship between miR-206 and HK2 was measured by dual-luciferase reporter assay. Glucose consumption, lactate production assay and ATP generation were performed in NSCLC cells following miR-206 and HK2 overexpression. We found that miR-206 was downregulated in NSCLC tissues and cells. miR-206 overexpression downregulated the expression of HK2 via targeting HK2 3'UTR in NSCLC cells. In addition, miR-206 decreased the cell viability and colony formation in NSCLC cells. Furthermore, miR-206 reduced glucose uptake, lactate production and ATP generation in NSCLC cells via HK2 repression. In conclusion, these findings suggested that miR-206 regulated NSCLC cell aerobic glycolysis by targeting HK2.

Lymphopenia in Esophageal Squamous Cell Carcinoma: Relationship to Malnutrition, Various Disease Parameters, and Response to Concurrent Chemoradiotherapy

Management of esophageal squamous cell carcinoma remains challenging, because detection often occurs at advanced stages and because of the high incidence of lymph node metastasis. This article focuses on whether lymphopenia is associated with response and tumor progression in patients with advanced esophageal squamous cell carcinoma who received concurrent chemotherapy.

Background.

Lymphopenia occurs commonly in esophageal squamous cell carcinoma (ESCC) and may influence treatment outcomes. We aimed to examine its association with treatment response and tumor progression in patients with locally advanced ESCC treated with concurrent chemoradiotherapy (CCRT).

Materials and Methods.

A total of 286 patients with stage II–IVa ESCC treated with CCRT between 2015 and 2017 were analyzed. Total lymphocyte counts were assessed at baseline, weekly, and 4 weeks after CCRT. Pretreatment lymphopenia was defined as total lymphocyte count <1,000 cells per mm³ at diagnosis, and treatment‐related lymphopenia was defined as total lymphocyte count <200 cells per mm³ with 6 weeks after starting CCRT. Univariate and multivariate logistic regression methods were used to analyze factors associated treatment‐related lymphopenia and treatment response.

Results.

Lymphopenia was observed in 44 patients (15.4%) at initial diagnosis. Pretreatment lymphopenia was significantly associated with greater tumor length, worse T status, body mass index ≤18.5 kg/m², and weight loss ≥3 kg in the previous 3 months. Six weeks after starting CCRT, 89 patients (31%) developed treatment‐related lymphopenia. Tumor progression and cancer‐related death were more frequently observed in treatment‐related lymphopenia group than those without (76.4% vs. 52.8% and 58.4% vs. 39.6%). A complete response (CR) was achieved in 62 patients (21.7%). In multivariate analysis, treatment‐related lymphopenia was significantly associated with lack of clinical CR, and older age, lower tumor location, greater tumor length, and larger planning target volume were independent predictors of treatment‐related lymphopenia.

Conclusion.

Treatment‐related lymphopenia during CCRT is an independent predictor for poor treatment response in ESCC.

Implications for Practice.

A total of 286 patients with locally advanced esophageal squamous cell carcinoma were treated with concurrent chemoradiotherapy (CCRT), and treatment‐related lymphopenia occurred in 31% of patients within 6 weeks from the start of CCRT. Treatment‐related lymphopenia was significantly associated with lack of treatment response, and older age, lower tumor location, greater tumor length, and larger planning target volume were independent predictors of treatment‐related lymphopenia. Lymphocyte count is an inexpensive biomarker that may be easily used by clinicians to identify patients who are most likely to benefit from CCRT.

Imaging Validation of Drug-Eluting Beads Transarterial Chemoembolization of Hepatocellular Carcinomas in Living Donor Liver Transplantation

OBJECTIVE

The aim of this study is to determine whether post-transarterial chemoembolization imaging (computed tomography or magnetic resonance imaging) could accurately predict the tumors' necrosis on pathologic specimens.

BACKGROUND

Transarterial chemoembolization with drug-eluting beads has been proven to be an effective way to bridge patients with hepatocellular carcinomas to liver transplantation.

MATERIALS AND METHODS

From September 2012 to June 2017, 59 patients with a total of 78 hepatocellular carcinomas, who received transarterial chemoembolization with drug-eluting beads before liver transplantation in Kaohsiung Chang Gung Memorial Hospital, were included in the study. All patients and hepatocellular carcinomas have pre-transarterial chemoembolization and post-transarterial chemoembolization images (computed tomography or magnetic resonance imaging) and pathological findings for correlation. Tumor response was evaluated according to modified Response Evaluation Criteria in Solid Tumors. The ranges of necrotic percentage are 100%, 91-99%, 51-90%, and <50%.

RESULTS

The accuracy rate between the imaging and pathology correlation was 40% for computed tomography and 42% for magnetic resonance imaging. The recurrent rate of the complete respond group is 11.5%, the partial respond group is 16.0%, and the stationary group is 28.6%.

CONCLUSION

Computed tomography and magnetic resonance imaging sensitivity is not satisfactory for microscopic evaluation of residual tumors after transarterial chemoembolization with drug-eluting beads. However, survival is good after liver transplantation no matter what the microscopic findings were.

Combination of long noncoding RNA MALAT1 and carcinoembryonic antigen for the diagnosis of malignant pleural effusion caused by lung cancer

Purpose

Long noncoding RNAs (lncRNAs) are present in body fluids, but their potential as tumor biomarkers has never been investigated in malignant pleural effusion (MPE) caused by lung cancer. The aim of this study was to assess the clinical significance of lncRNAs in pleural effusion, which could potentially serve as diagnostic and predictive markers for lung cancer-associated MPE (LC-MPE).

Patients and methods

RNAs from pleural effusion were extracted in 217 cases of LC-MPE and 132 cases of benign pleural effusion (BPE). Thirty-one lung cancer-associated lncRNAs were measured using quantitative real-time polymerase chain reaction (qRT-PCR). The level of carcinoembryonic antigen (CEA) was also determined. The receiver operating characteristic (ROC) curves and the area under the ROC curve (AUC) were established to evaluate the sensitivity and specificity of the identified lncRNAs and other biomarkers. The correlations between baseline pleural effusion lncRNAs expression and response to chemotherapy were also analyzed.

Results

Three lncRNAs (MALAT1, H19, and CUDR) were found to have potential as diagnostic markers in LC-MPE. The AUCs for MALAT1, H19, CUDR, and CEA were 0.891, 0.783, 0.824, and 0.826, respectively. Using a logistic model, the combination of MALAT1 and CEA (AUC, 0.924) provided higher sensitivity and accuracy in predicting LC-MPE than CEA (AUC, 0.826) alone. Moreover, baseline MALAT1 expression in pleural fluid was inversely correlated with chemotherapy response in patients with LC-MPE.

Conclusion

Pleural effusion lncRNAs were effective in differentiating LC-MPE from BPE. The combination of MALAT1 and CEA was more effective for LC-MPE diagnosis.

Systemic immune-inflammation index predicting chemoradiation resistance and poor outcome in patients with stage III non-small cell lung cancer

Background

There is increasing evidence that the existence of systemic inflammation response is correlated with poor prognosis in several solid tumors. The aim of this retrospective study was to investigate the association between systemic immune-inflammation index (SII) and therapy response and overall survival in patients with stage III non-small cell lung cancer (NSCLC). The prognostic values of neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and prognostic nutritional index (PNI) were also evaluated.

Methods

In total, 332 patients with new diagnosis of stage III NSCLC were included in this retrospective analysis. SII was defined as platelet counts × neutrophil counts/lymphocyte counts. Receiver operating characteristic (ROC) curve was used to evaluate the optimal cut-off value for SII, NLR, PLR and PNI. Univariate and multivariate survival analysis were performed to identify the factors correlated with overall survival.

Results

Applying cut-offs of ≥ 660 (SII), ≥ 3.57 (NLR), ≥ 147 (PLR), ≤ 52.95 (PNI), SII ≥ 660 was significantly correlated with worse ECOG PS (< 0.001), higher T stage (< 0.001), advanced clinical stage (p = 0.019), and lower response rate (p = 0.018). In univariate analysis, SII ≥ 660, NLR ≥ 3.57, PLR ≥ 147, and PNI ≤ 52.95 were significantly associated with worse overall survival (p_all < 0.001). Patients with SII ≥ 660 had a median overall survival of 10 months, and patients with SII < 660 showed a median overall survival of 30 months. In multivariate analysis only ECOG PS (HR, 1.744; 95% CI 1.158–2.626; p = 0.008), T stage (HR, 1.332; 95% CI 1.032–1.718; p = 0.028), N stage (HR, 1.848; 95% CI 1.113–3.068; p = 0.018), SII (HR, 2.105; 95% CI 1.481–2.741; p < 0.001) and NLR ≥ 3.57 (HR, 1.934; 95% CI 1.448–2.585; p < 0.001) were independently correlated with overall survival.

Conclusions

This study demonstrates that the SII is an independent prognostic indicator of poor outcomes for patients with stage III NSCLC and is superior to other inflammation-based factors in terms of prognostic ability.

Systemic immune-inflammation index predicting chemoradiation resistance and poor outcome in patients with stage III non-small cell lung cancer

BACKGROUND

There is increasing evidence that the existence of systemic inflammation response is correlated with poor prognosis in several solid tumors. The aim of this retrospective study was to investigate the association between systemic immune-inflammation index (SII) and therapy response and overall survival in patients with stage III non-small cell lung cancer (NSCLC). The prognostic values of neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and prognostic nutritional index (PNI) were also evaluated.

METHODS

In total, 332 patients with new diagnosis of stage III NSCLC were included in this retrospective analysis. SII was defined as platelet counts × neutrophil counts/lymphocyte counts. Receiver operating characteristic (ROC) curve was used to evaluate the optimal cut-off value for SII, NLR, PLR and PNI. Univariate and multivariate survival analysis were performed to identify the factors correlated with overall survival.

RESULTS

Applying cut-offs of ≥ 660 (SII), ≥ 3.57 (NLR), ≥ 147 (PLR), ≤ 52.95 (PNI), SII ≥ 660 was significantly correlated with worse ECOG PS (< 0.001), higher T stage (< 0.001), advanced clinical stage (p = 0.019), and lower response rate (p = 0.018). In univariate analysis, SII ≥ 660, NLR ≥ 3.57, PLR ≥ 147, and PNI ≤ 52.95 were significantly associated with worse overall survival (p _all < 0.001). Patients with SII ≥ 660 had a median overall survival of 10 months, and patients with SII < 660 showed a median overall survival of 30 months. In multivariate analysis only ECOG PS (HR, 1.744; 95% CI 1.158-2.626; p = 0.008), T stage (HR, 1.332; 95% CI 1.032-1.718; p = 0.028), N stage (HR, 1.848; 95% CI 1.113-3.068; p = 0.018), SII (HR, 2.105; 95% CI 1.481-2.741; p < 0.001) and NLR ≥ 3.57 (HR, 1.934; 95% CI 1.448-2.585; p < 0.001) were independently correlated with overall survival.

CONCLUSIONS

This study demonstrates that the SII is an independent prognostic indicator of poor outcomes for patients with stage III NSCLC and is superior to other inflammation-based factors in terms of prognostic ability.

High expression of long non-coding RNA AFAP1-AS1 predicts chemoradioresistance and poor prognosis in patients with esophageal squamous cell carcinoma treated with definitive chemoradiotherapy

To evaluate the clinical significance of lncRNAs in the resistance to cisplatin‐based chemoradiotherapy in esophageal squamous cell carcinoma (ESCC). We focused on lncRNAs which were frequently reported in ESCC or were involved in chemoradiotherapy resistance. LncRNA expressions were examined in paired cisplatin‐resistant and parental ESCC cell lines. Dysregulated lncRNAs were further measured in 162 pretreatment biopsy specimens of ESCC who received definitive chemoradiotherapy (dCRT). Then the correlations between lncRNA expression and response to dCRT and prognosis were analyzed. Three lncRNAs (AFAP1‐AS1, UCA1, HOTAIR) were found to be deregulated in cisplatin‐resistant cells compared with their parent cells. AFAP1‐AS1 was significantly up‐regulated in tumor tissues compared with adjacent normal tissues (P = 0.006). Furthermore, overexpression of AFAP1‐AS1 was closely associated with lymph node metastasis (P < 0.001), distant metastasis (P = 0.016), advanced clinical stage (P = 0.002), and response to dCRT (P < 0.001). Kaplan–Meier survival analysis revealed that high expression of AFAP1‐AS1 was significantly associated with shorter progression free survival (PFS) (median, 15 months vs. 27 months, P < 0.001) and overall survival (OS) (median, 29 months vs. 42 months, P < 0.001). In the multivariate analysis, high expression of AFAP1‐AS1 was found to be an independent risk factor to predict poor PFS (HR, 1.626; P = 0.027) and OS (HR, 1.888; P = 0.004). Thus, high expression of AFAP1‐AS1 could serve as a potential biomarker to predict tumor response and survival. Determination of this lncRNA expression might be useful for selection ESCC patients for dCRT. © 2016 The Authors. Molecular Carcinogenesis published by Wiley Periodicals, Inc.

Implication of lncRNAs in pathogenesis of esophageal cancer

Long non-coding RNAs (lncRNAs), transcripts as longer than 200 nt in length with a great number of varieties in human genomics, play important roles in the regulation of genetics and epigenetics including gene transcription and post-transcription. Increasing evidence have demonstrated the upregulation of lncRNAs in tumorigenesis and metastasis of esophageal cancer (EC), a type of malignant tumors particularly in Asia. In this review, we briefly discuss the profiles and functions of lncRNAs involved in the progression of EC, which may provide a new approach to improve EC diagnosis and treatment.

Identification of the long non-coding RNA POU3F3 in plasma as a novel biomarker for diagnosis of esophageal squamous cell carcinoma

Background

Recent studies have demonstrated that long non-coding RNAs (lncRNAs) were present in the blood of cancer patients and have shown great potential as powerful and non-invasive tumor markers. However, little is known about the value of lncRNAs in the diagnosis of esophageal squamous cell carcinoma (ESCC). We hypothesized that ESCC-related lncRNAs might be released into the circulation during tumor initiation and could be utilized to detect and monitor ESCC.

Methods

Ten lncRNAs (HOTAIR, AFAP1-AS1, POU3F3, HNF1A-AS1, 91H, PlncRNA1, SPRY4-IT1, ENST00000435885.1, XLOC_013104 and ENST00000547963.1) which previously found to be differently expressed in esophageal cancer were selected as candidate targets for subsequent circulating lncRNA assay. A four-stage exploratory study was conducted to test the hypothesis: (1) optimization of detected method to accurately and reproducibly measure ESCC-related lncRNAs in plasma and serum; (2) evaluation of the stability of circulating lncRNAs in human plasma or serum; (3) exploration the origin of ESCC-related lncRNAs in vitro and in vivo; (4) evaluation the diagnostic power of circulating lncRNAs for ESCC.

Results

ESCC-related lncRNAs were detectable and stable in plasma of cancer patients, and derived largely from ESCC tumor cells. Furthermore, plasma levels of POU3F3, HNF1A-AS1 and SPRY4-IT1 were significantly higher in ESCC patients compared with normal controls. By receiver operating characteristic curve (ROC) analysis, among the three lncRNAs investigated, plasma POU3F3 provided the highest diagnostic performance for detection of ESCC (the area under the ROC curve (AUC), 0.842; p < 0.001; sensitivity, 72.8%; specificity, 89.4%). Moreover, use of POU3F3 and SCCA in combination could provide a more effective diagnosis performance (AUC, 0.926, p < 0.001, sensitivity, 85.7%; specificity, 81.4%). Most importantly, this combination was effective to detect ESCC at an early stage (80.8%).

Conclusions

Plasma POU3F3 could serve as a potential biomarker for diagnosis of ESCC, and the combination of POU3F3 and SCCA was more efficient for ESCC detection, in particular for early tumor screening.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-14-3) contains supplementary material, which is available to authorized users.

Long noncoding RNA SPRY4-IT1 is upregulated in esophageal squamous cell carcinoma and associated with poor prognosis

LncRNA SPRY4-IT1 has been shown to promote the progression of melanoma. However, the role of lncRNA SPRY4-IT1 in human esophageal squamous cell carcinoma (ESCC) remains unclear. The purpose of this study is to investigate the clinical significance and biological functions of SPRY4-IT1 in ESCC. The expression levels of lncRNA SPRY4-IT in 92 ESCC patients and 8 ESCC cell lines were evaluated by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). The prognostic significance was evaluated using Kaplan-Meier and Cox regression analyses. Small interfering RNA (siRNA) was used to suppress SPRY4-IT1 expression in ESCC cell lines. Both in vitro and in vivo assays were performed to further explore its role in tumor progression. SPRY4-IT1 levels were significantly higher in ESCC tissues and cells than in corresponding adjacent noncancerous tissues and nontumorigenic esophageal epithelial cells, and the ESCC patients with higher SPRY4-IT1 expression had an advanced clinical stage and poorer prognosis than those with lower SPRY4-IT1 expression. The multivariate analysis revealed that SPRY4-IT1 expression level is an independent prognostic factor in ESCC patients. In vitro assays demonstrated that knockdown of SPRY4-IT1 reduced cell proliferation, invasiveness, and migration. In vivo assays demonstrated that knockdown of SPRY4-IT1 decreases cell growth. SPRY4-IT1 is a novel molecule involved in ESCC progression, which may provide a potential prognostic biomarker and a potential target for therapeutic intervention.

Upregulation of the long non-coding RNA PlncRNA-1 promotes esophageal squamous carcinoma cell proliferation and correlates with advanced clinical stage

BACKGROUND

Recent studies revealed that long noncoding RNAs (lncRNAs) play critical regulatory roles in cancer biology. PlncRNA-1 is one of lncRNAs that is associated with cell apoptosis and proliferation of prostate cancer.

AIM

This study aimed to assess the potential role of PlncRNA-1 in the pathogenesis of esophageal squamous cell carcinoma (ESCC).

MATERIALS AND METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression level of PlncRNA-1 in 73 pairs of ESCC and their matched normal tissues. The correlation of PlncRNA-1 with clinicopathological features and clinical stages was also analyzed. Cancer cell proliferation and apoptosis were assessed following knock-down of PlncRNA-1 by MTT, colony formation assay, and flow cytometry.

RESULTS

The expression of PlncRNA-1 was significantly higher in human ESCC compared with the adjacent noncancerous tissues (69.8 %, p < 0.05), and the high level of PlncRNA-1 expression was significantly correlated with advanced clinical stage (p < 0.01) and lymph node metastasis (p < 0.05). Furthermore, knockdown of PlncRNA-1 reduced cell proliferation and increased the apoptosis in vitro.

CONCLUSIONS

PlncRNA-1 plays an important role in ESCC cell proliferation. Overexpression of PlncRNA-1 is correlated with advanced tumor stage and lymph node metastasis, and may serve as a potential prognostic marker and therapeutic target for ESCC.

Brachytherapy with iodine-125 seeds for hepatocellular carcinoma

¹²⁵I seeds have good physical and radiobiological characteristics. Interstitial brachytherapy has advantages of minimal invasive, precise stereotactic treatment and high local control rate and plays an important role in the treatment of hepatocellular carcinoma (HCC). Brachytherapy with ¹²⁵I seeds has been used in unresectable HCC, HCC with portal vein tumor thrombus, intrahepatic cholangiocarcinoma, hepatic metastases, and some other tumors, providing encouraging survival rates. Radiation-related complications are rare in highly selected patients. In a word, ¹²⁵I brachytherapy is a safe and effective treatment for newly diagnosed or recurrent unresectable intrahepatic malignancies and can provide better survival rates and decent quality of life.

Specificity of guinea pig liver transglutaminase for amine substrates

The amine specificity of guinea pig liver transglutaminase, a model enzyme for endo-gamma-glutamine:epsilon-lysin transferases, was explored with the aid of synthetic substrates of high apparent affinities. As exemplified by dansyl- (5-dimethylamino-1-naphthalenesulfonyl), (2,4-dinitrobenzenesulfonyl)-, and (2,4,6-triisopropylbenzenesulfonyl)-cadaverines--each of which showed affinities of approximately 4 x 10(7) M-1--the best amine substrates carried a large hydrophobic substituent attached to an alkylamine side chain of about 7.2 A in length. Altogether, our results point to the importance of a hydrophobic binding region in the enzyme from where the alkyl side chain reaches into a narrow crevice toward the active center and positions the primary amine of the substrate for attacking the carbonyl group of the acyl enzyme intermediate.

Transamidase kinetics. Amide formation in the enzymic reactions of thiol esters with amines

1. Beta-Phenylpropionylthiocholine and N-(5-aminopentyl)-5-dimethylaminonaphthalene-1-sulphonamide (dansylcadaverine) serve as a pair of water-soluble (pH7.5) model substrates for transamidating enzymes. Amide formation could be followed directly through fluorescence measurements by monitoring the continuous extraction of the water-soluble coupling product, N-(beta-phenylpropionyl)dansylcadaverine, into n-heptane. By this procedure, the steady-state kinetics of glutamine-lysine endo-gamma-glutamyltransferase from human plasma (fibrinoligase, thrombin- and Ca2+-activated blood coagulation Factor XII) and from guinea-pig liver (liver transglutaminase) were investigated at 25 degrees C. 2. With beta-phenylpropionylthiocholine as the varied substrate, Lineweaver-Burk plots with various concentrations of dansylcadaverine intercept on the horizontal axis, suggesting that formation of the acyl-enzyme is rate limiting. 3. On the basis of functional normality of active sites, kcat. values of 1.8 s(-1) and 0.9 s(-1) were obtained for the plasma and liver gamma-glutamyltransferase respectively. The two enzymes show identical affinities for the first substrate, beta-phenylpropionylthiocholine, with Ka 4 times 10(-4) M. 4. Utilization of the second substrate, dansylcadaverine, appears to be an order of magnitude more efficient with the liver enzyme. 5. N-(5-Amino-3-thiapentyl)-5-dimethylaminonaphthalene-1-sulphonamide (dansylthiacadaverine) could be used instead of dansylcadaverine in the fluorescent kinetic system. 6. Competitive inhibition by a non-fluorescent amine substrate histamine was also evaluated.