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Post-radiotherapy plasma total glutathione is associated to outcome in patients with head and neck squamous cell carcinoma

作者： Siv Kjølsrud Bøhna, Sigbjørn Smelandb, Amrit Kaur Sakhia, Magne Thoresena et al出處： Cancer Letters 238 (2006) 240–247

報告者：中國醫藥大學 林佳璇指導營養師：吳素珍 營養師

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Introduction

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The function of thiols• Thiols have essential roles in many

biochemical reactions by virtue of their ability to be reversibly oxidized

• Several low-molecular-weight-thiols are actively involved in cellular defenses against toxic exposure (Dickinson et al,2002)Homocysteine

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Glutathione (GSH)• GSH is present in all mammalian cells

• It consists of cysteine,glutamate and glycine

• glycine

cysteine

glutamate

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r-glutamylcysteine syntethase

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The function of glutathione• It is the most important intracellular thiol-

based redox buffer (Dickinson et al,2002)

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• Plasma GSH may be used as a biomarker for oxidative stress (Therond et al,2002)

2GSH

GSSG

H2O2

2H2O

Glutathione peroxidase

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Oxidative stress

• It can damage to DNA and thereby promote carcinogenesis (Seidman et al,1999)

• Many malignant cells have alterations in GSH-related mechanism or modify the concentration of GSH to cope with oxidative stress (Tatebe et al,2002)

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Head and neck squamous cell carcinoma (HNSCC)

• Tobacco and alcohol are clearly defined as etiologic factors for these malignancies (Seidman et al,1999)

• These factors are known to increase ROS and RNS production and to induce cellular oxidative damage

• HNSCC with strongest link to oxidative damage and oxidative stress because of tobacco and alcohol

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The purpose

• To address the role of systemic oxidative stress for survival of HNSCC patients, we have assessed low-molecular-weight-thiols in post-radiotherapy plasma of patients with HNSCC.

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Subjects and methods

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Selection of patients and controlsPatients Controls

Amount 29 HNSCC 51 healthy

gender M:22 F:7 M:31 F:20

TNM stage Ⅰ:5 :2 :7 :15Ⅱ Ⅲ Ⅳ

Tumor location Epipharynx:2 Larynx:8 Oro/hypopharynx:16 Other:3

Smoking status Smoker:19 Former smoker:2 Non smoker:4 Not known:4

Smoker:21 non smoker:30

Therapy dose 60-70Gy

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Plasma collection

29 HNSCC patients

Post-radiotherapy After 6 weeks

Collect citrate plasma

51 healthy controls

Collect EDTA plasma

Keep at -70℃

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Chromatographic analysis of total thiols

Collect plasma

chromatographic analyses

GSH , cysteine , homocysteine , cysteinyl-glycine

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Statistical analysis

patients–controls →

survivors–non-survivors

two-sample t-test.

sex, smoking and BMI → ANCOVA

P ＜ 0.05

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Results

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Plasma thiols in HNSCC patients and controls

No significant

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Plasma thiols immediately after radiotherapy and after 6 weeks follow-up

• There were no significant changes in any of the thiols between the first plasma sample and the 6 week follow-up (P>0.33)

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Survival versus plasma total thiol values

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Discussion

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Plasma GSH level and survival rate

• There were no significant in total dose or dose-intensity of the radiotherapy given in the two group

• The patients with the lowest plasma total GSH levels had the lowest survival rate

3 out of 14 died

11 out of 15 died

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The relation of GSH and immune function

• With Low GSH

T cellIL-2 production,IL-2 response, cytotoxic T cell activity

NK cellkilling activity• High blood NK-cell activity have a significant

longer survival time than those with low NK activity (Kinscherf,1994)

• It may be related to the study of reduced survival in patients with low plasma total GSH

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• The patients with HIV infection disturbed GSH homeostasis in the immunopathogenesis for both plasma and intracellular GSH levels are reduced (Staal,1992)

• The therapy with N-acetylcysteine, alone or in combination with other antioxidants restores GSH levels and improves immune function in HIV-infected individuals (Mullaer,2000)

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N-acetylcysteine

• N-acetylcysteine (NAC) is an amine protected version of cysteine that is rapidly hydrolyzed in the body to the amino acid cysteine

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The relation of GSH and radiotherapy

• Total GSH measured of healthy adults in this study were 4.56±1.71uM

• Previous studies reported about 2-3uM (Jones,2002)

• The levels of free GSH+GSSG were reduce in plasma following radiotherapy (Jadhav,1998)

• The total GSH levels in post-radiotherapy plasma of HNSCC patients were about 20% lower than in the controls

GSH+GSSG+GSSR

GSH+GSSG

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Conclusion

• Total GSH levels in post-radiotherapy plasma were lower in HNSCC patients than controls

• The patients with the lowest plasma total GSH levels had the lowest survival rate

• We suggest that HNSCC patients that develop excessive systemic oxidative stress, as assessed by low total GSH in plasma

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Problem

• 為何 patients組和 controls組的血漿收集所使用的抗凝固劑不同？

• 為何之前的研究所測的血漿 total GSH 是free GSH ＋ GSSG，而本篇作者測的是free GSH ＋ GSSG ＋ GSSR？

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補充資料

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HNSCC

•頭頸部鱗狀細胞癌常見的有鼻咽癌 , 副鼻竇癌 , 舌癌 , 喉癌 , 下咽癌

•鼻咽癌在台灣的男性發生率為第十位 , 死亡率為第九位

•喉癌常見於男性 , 佔台灣惡性腫瘤的 4%,在台灣男性比女性的發生率為 8:1

•喜好抽煙 , 喝酒發生率較高

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影響 GSH的因子

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Selenium

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食物中硒的含量

食物 含量 (ug)

巴西堅果 1/4cup 380

大比目魚 3 oz 113

鮭魚 3 oz 70

貝類 3 oz 70

小麥胚芽 1/4cup 28

(Krause’s)

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Vitamin B2

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食物中 Vit B2的含量

食物 含量 (mg)

豬肝 100g 4.28

烏魚子 100g 2.39

紅蟳 100g 0.94

脫脂高鈣鮮奶 100g 0.36

低脂乳酪 100g 0.76

(行政院衛生署 )

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Thanks for your attention !