De-repression of Anti-Cancer Immunity by N-Acetylcysteine

Author: Emiliano Rapoport

Affiliation: Andromeda Biotherapeutics
Date Published: Friday October 20th, 2006 @ 00:21:42 EST

Comments: No comments
From Category: Immunology


This paper describes a method of treating cancer through de-repression of anticancer immune responses using a drug that is already in clinical use for treatment of acetaminophen overdose.


§ We propose a small pilot study administering N-acetylcysteine to advanced cancer patients with the objectives of:

o Suppressing neutrophil hyperactivation
o Suppressing markers of oxidative stress/inflammation
o Restoring TCR-zeta chain expression and IFN-g production in patient T cells


§ Tumor patients suffer from antigen-specific and non-specific suppression of T cell function. This is why current immunotherapies are failing. If the T cells don’t work how will cancer vaccines do anything?

§ Suppression of T cell function is due in part to H2O2 produced by activated neutrophils that are circulating systemically.

§ Co-culture of neutrophils from cancer patients with healthy person T cells causes T cells to lose zeta-chain of TCR. This results in functional inactivation.

§ Addition of catalase to cancer patient neutrophils blocks ability to suppress healthy T cells.

§ Systemic neutrophil activation in cancer patients can be easily assessed: The neutrophils in cancer patients co-purify with lymphocytes on Ficoll gradient because of their activation status. Flow cytometry of Ficoll gradient separated cells shows distinct differences cells of cancer patients and control patients.

§ N-acetylcysteine is a safe drug clinically used for treatment of acetominophen poisoning and lung disorders.

§ N-acetylcysteine is a promising therapy for blocking neutrophil hyperactivation in cancer patients since:
o It blocks neutrophil hyperactivation in sepsis patients.
o It blocks neutrophil hyperactivation clinically in inflammatory conditions.
o Restores immune function in animal models of sepsis-induced immune suppression.
o Blocks angiogenesis
o Directly suppresses proliferation of cancer cells but not normal counterparts in vitro.

Is there such a thing as cancer-associated immune suppression?

Immune suppression by cancer has been well-documented in advanced cancer patients possessing a variety of malignancies. These include pancreatic cancer, breast cancer, renal cancer, colorectal cancer and melanoma. Suppression is noted by diminished T cell proliferative response, diminished ability to produce IFN-g, and diminished ability to induce recall responses to normal antigens [1-8].

What is the importance of tumor-induced immune suppression?
Immune suppression does not allow for proper eradication of tumors by immunotherapy, or by the body’s natural mechanisms. Correlation between immune suppression and poor prognosis has been extensively noted [9-11].

What is the molecular basis for tumor-induced immune suppression?

The tumor cells induce cleavage of the T cell receptor zeta (TCR-z) chain through a caspase-3 dependent manner [12, 13]. This is both FasL-dependent and independent. Since TCR-z is critical for signal transduction, the T cells become unable to respond to tumor antigens. Originally, the suppressed level of TCR-z was described in tumor bearing mice [14, 15] and subsequently in patients. Olivera Finn from University of Pittsburgh described suppressed TCR-z expression in advanced cancer patients [16]. Similar data has been reported for a wide variety of cancers [17-21]. The correlation between suppressed TCR-z and suppressed IFN-g production has also been reported [17].

How does the tumor suppress TCR-z?
The cause of TCR-z suppression has been attributed, at least in part, to reactive oxygen radicals produced by:

A) The inflammatory activity occurring inside the tumor (it is well established that there is a constant area of necrosis intratumorally
B) Macrophages associated with the tumor.
C) Neutrophils activated directly by the tumor, or by the tumor associated macrophages.

Tumors usually associated with macrophage infiltration, this is correlated with tumor stage and is believed to contribute to tumor progression by stimulation of angiogenesis [22-24]. Cytokines such as M-CSF [22] and VEGF [25] produced by tumor infiltrating macrophages are essential for tumor progression to malignancy. In fact, tumors implanted into M-CSF deficient op/op mice (they lack macrophages) do not metastasize or become vascularized [26]. Tumor-associated macrophages possess an activated phenotype and release various inflammatory mediators such as cyclo-oxygenase metabolites [27, 28], TNF-a [29], and IL-6 [30].

In addition, tumor associated macrophages produce large amounts of free radicals such as NO, OH, and H2O2 [31-33]. The high levels of macrophage activation in cancer patients is illustrated by high serum levels of neopterin, a feature that is associated with poor prognosis [34].

What evidence is there that the tumor itself causes non-specific inflammation that could activate neutrophils?

In addition to oxidative stress elaborated by tumor associated macrophages, the presence of the tumor itself causes systemic changes associated with chronic inflammation. Erythrocyte sedimentation ration, C-reactive protein and IL-6 are markers of inflammatory stress used to designate progression of diseases such as arthritis [35, 36]. Interestingly advanced cancer patients possess all of these inflammatory markers [37-41]. Another marker of chronic inflammation is decreased albumin synthesis by the liver, this is also seen in cancer patients and is believed to contribute, in part, to cachexia [42, 43]. In addition, the inflammatory marker fibrinogen D-dimers is also higher in cancer patients as opposed to controls [44-46].

How can we assess activated neutrophils in cancer patients?

Schmielau et al reported that in patients with a variety of cancers, activated neutrophils are circulating in large numbers [16]. These neutrophils secrete reactive oxygen radicals such as hydrogen peroxide which trigger suppression of TCR-z and IFN-g production. This was demonstrated by co-incubation of the neutrophils from cancer patients with lymphocytes from healthy volunteer. A profound suppression of TCR-z expression was seen. Evidence for the critical role of hydrogen peroxide was shown by the fact that addition of catalase suppressed TCR-z downregulation. A simple method of assessing the number of circulating activated neutrophils was described in the same paper. This method involves collecting peripheral blood from patients, spinning the blood on a density gradient such as Ficoll, and collecting the lymphocyte fraction. While in healthy volunteers the lymphocyte fraction contained primarily lymphocytes, in cancer patients the lymphocyte fraction contained both lymphocytes and a large number of neutrophils. The reason why these neutrophils are present in the lymphocyte fraction is because activation alters their density so that they co-purify differently on the gradient.

Any evidence for clinical improvement after neutrophil depletion?

A potential indication of the importance of activated neutrophils to cancer progression is provided by Tabuchi et al who show that removal of granulocytes from the peripheral blood of cancer patients resulted in reduced tumor size, unfortunately, the study was performed in only 2 patients [47].

What is known about oxidative stress and immune response?

As a mechanism to compensate for immune over-activation, mediators of inflammation have immune suppressive properties. This is best illustrated in the immune suppression seen following immune hyperactivation such as in septic shock. Following the primary scepticemia, patients are systemically immune compromised due to circulating immune suppressive factors that are released in response to the inflammatory stress. This suppression is termed compensatory anti-inflammatory response syndrome (CARS) and is associated with many opportunistic infections and deactivation [48]. The clinical importance of CARS immune suppression is seen in that sepsis survivors show normal T-cell proliferation and IL-2 release, whereas those that succumb possess suppressed T cell responses [49].

What do CARS and cancer have in common?

Interestingly immune suppressive mediators associated with CARS such as PGE2, TGF-b, and IL-10 are also associated with cancer-induced immune suppression [50]. The role of oxidative stress in sepsis-induced immune suppression was recently demonstrated in experiments where administration of antioxidants (ascorbic acid or n-acetylcysteine) to animals undergoing experimental sepsis blocked immune suppression [51]. Another example of the potential for antioxidants to stimulate immune response in an inflammatory condition is in patients with Duke’s C and D colorectal cancer who were administred of a daily dose of 750 mg of vitamin E for 2 weeks. This resulted in restoration of IFN-g and IL-2 production [52].

Has N-acetylcysteine been used in the past besides acetominophen poisoning?

Yes, to name a few…
A) The problem of uncontrolled inflammation is seen in sepsis. Although as a monotherapy n-acetylcysteine has little clinical effect, therapeutic administration of n-acetylcysteine results in suppression of the constitutively activated neutrophils seen in these patients [53].

B) Administration of n-acetylcysteine to smokers results in suppression of markers of oxidative stress [54].

C) Oral n-acetylcysteine blocks angiogenesis and suppresses growth of Kaposi Sarcoma [55].


1. Ng, C.S., et al., Mechanisms of immune evasion by renal cell carcinoma: tumor-induced T-lymphocyte apoptosis and NFkappaB suppression. Urology, 2002. 59(1): p. 9-14.
2. Campbell, J.D., et al., Suppression of IL-2-induced T cell proliferation and phosphorylation of STAT3 and STAT5 by tumor-derived TGF beta is reversed by IL-15. J Immunol, 2001. 167(1): p. 553-61.
3. Beck, C., H. Schreiber, and D. Rowley, Role of TGF-beta in immune-evasion of cancer. Microsc Res Tech, 2001. 52(4): p. 387-95.
4. Almand, B., et al., Increased production of immature myeloid cells in cancer patients: a mechanism of immunosuppression in cancer. J Immunol, 2001. 166(1): p. 678-89.
5. Dix, A.R., et al., Immune defects observed in patients with primary malignant brain tumors. J Neuroimmunol, 1999. 100(1-2): p. 216-32.
6. Kiessling, R., et al., Tumor-induced immune dysfunction. Cancer Immunol Immunother, 1999. 48(7): p. 353-62.
7. Kim, H.J., J.K. Park, and Y.G. Kim, Suppression of NF-kappaB activation in normal T cells by supernatant fluid from human renal cell carcinomas. J Korean Med Sci, 1999. 14(3): p. 299-303.
8. Ungefroren, H., et al., Immunological escape mechanisms in pancreatic carcinoma. Ann N Y Acad Sci, 1999. 880: p. 243-51.
9. Fischer, J.R., et al., Decrease of interleukin-2 secretion is a new independent prognostic factor associated with poor survival in patients with small-cell lung cancer. Ann Oncol, 1997. 8(5): p. 457-61.
10. Ishigami, S., et al., CD3-zetachain expression of intratumoral lymphocytes is closely related to survival in gastric carcinoma patients. Cancer, 2002. 94(5): p. 1437-42.
11. Marana, H.R., et al., Reduced immunologic cell performance as a prognostic parameter for advanced cervical cancer. Int J Gynecol Cancer, 2000. 10(1): p. 67-73.
12. Gastman, B.R., et al., Tumor-induced apoptosis of T lymphocytes: elucidation of intracellular apoptotic events. Blood, 2000. 95(6): p. 2015-23.
13. Takahashi, A., et al., Elevated caspase-3 activity in peripheral blood T cells coexists with increased degree of T-cell apoptosis and down-regulation of TCR zeta molecules in patients with gastric cancer. Clin Cancer Res, 2001. 7(1): p. 74-80.
14. Mizoguchi, H., et al., Alterations in signal transduction molecules in T lymphocytes from tumor-bearing mice. Science, 1992. 258(5089): p. 1795-8.
15. Horiguchi, S., et al., Primary chemically induced tumors induce profound immunosuppression concomitant with apoptosis and alterations in signal transduction in T cells and NK cells. Cancer Res, 1999. 59(12): p. 2950-6.
16. Schmielau, J. and O.J. Finn, Activated granulocytes and granulocyte-derived hydrogen peroxide are the underlying mechanism of suppression of t-cell function in advanced cancer patients. Cancer Res, 2001. 61(12): p. 4756-60.
17. Kim, C.W., et al., Alteration of signal-transducing molecules and phenotypical characteristics in peripheral blood lymphocytes from gastric carcinoma patients. Pathobiology, 1999. 67(3): p. 123-8.
18. Laytragoon-Lewin, N., et al., Alteration of cellular mediated cytotoxicity, T cell receptor zeta (TcR zeta) and apoptosis related gene expression in nasopharyngeal carcinoma (NPC) patients: possible clinical relevance. Anticancer Res, 2000. 20(2B): p. 1093-100.
19. Taylor, D.D., et al., Modulation of TcR/CD3-zeta chain expression by a circulating factor derived from ovarian cancer patients. Br J Cancer, 2001. 84(12): p. 1624-9.
20. Chen, X., et al., Impaired expression of the CD3-zeta chain in peripheral blood T cells of patients with chronic myeloid leukaemia results in an increased susceptibility to apoptosis. Br J Haematol, 2000. 111(3): p. 817-25.
21. Healy, C.G., et al., Impaired expression and function of signal-transducing zeta chains in peripheral T cells and natural killer cells in patients with prostate cancer. Cytometry, 1998. 32(2): p. 109-19.
22. Valkovic, T., et al., Correlation between vascular endothelial growth factor, angiogenesis, and tumor-associated macrophages in invasive ductal breast carcinoma. Virchows Arch, 2002. 440(6): p. 583-8.
23. Makitie, T., et al., Tumor-infiltrating macrophages (CD68 cells) and prognosis in malignant uveal melanoma. Invest Ophthalmol Vis Sci, 2001. 42(7): p. 1414-21.
24. Leek, R.D., et al., Association of macrophage infiltration with angiogenesis and prognosis in invasive breast carcinoma. Cancer Res, 1996. 56(20): p. 4625-9.
25. Lewis, J.S., et al., Expression of vascular endothelial growth factor by macrophages is up-regulated in poorly vascularized areas of breast carcinomas. J Pathol, 2000. 192(2): p. 150-8.
26. Nowicki, A., et al., Impaired tumor growth in colony-stimulating factor 1 (CSF-1)-deficient, macrophage-deficient op/op mouse: evidence for a role of CSF-1-dependent macrophages in formation of tumor stroma. Int J Cancer, 1996. 65(1): p. 112-9.
27. Kamate, C., et al., Inflammation and cancer, the mastocytoma P815 tumor model revisited: triggering of macrophage activation in vivo with pro-tumorigenic consequences. Int J Cancer, 2002. 100(5): p. 571-9.
28. Young, M.R., et al., Suppressor alveolar macrophages in mice bearing metastatic Lewis lung carcinoma tumors. J Leukoc Biol, 1987. 42(6): p. 682-8.
29. Billingsley, K.G., et al., Macrophage-derived tumor necrosis factor and tumor-derived of leukemia inhibitory factor and interleukin-6: possible cellular mechanisms of cancer cachexia. Ann Surg Oncol, 1996. 3(1): p. 29-35.
30. Bonta, I.L. and S. Ben-Efraim, Involvement of inflammatory mediators in macrophage antitumor activity. J Leukoc Biol, 1993. 54(6): p. 613-26.
31. Bhaumik, S. and A. Khar, Induction of nitric oxide production by the peritoneal macrophages after intraperitoneal or subcutaneous transplantation of AK-5 tumor. Nitric Oxide, 1998. 2(6): p. 467-74.
32. Lewis, J.G. and D.O. Adams, Inflammation, oxidative DNA damage, and carcinogenesis. Environ Health Perspect, 1987. 76: p. 19-27.
33. Kono, K., et al., Hydrogen peroxide secreted by tumor-derived macrophages down-modulates signal-transducing zeta molecules and inhibits tumor-specific T cell-and natural killer cell-mediated cytotoxicity. Eur J Immunol, 1996. 26(6): p. 1308-13.
34. Murr, C., et al., Neopterin as a marker for immune system activation. Curr Drug Metab, 2002. 3(2): p. 175-87.
35. Whisler, R.L., L.S. Gray, and K.V. Hackshaw, Rheumatology, a clinical overview. Clin Podiatr Med Surg, 2002. 19(1): p. 149-61, vii.
36. Ishihara, K. and T. Hirano, IL-6 in autoimmune disease and chronic inflammatory proliferative disease. Cytokine Growth Factor Rev, 2002. 13(4-5): p. 357.
37. Mahmoud, F.A. and N.I. Rivera, The role of C-reactive protein as a prognostic indicator in advanced cancer. Curr Oncol Rep, 2002. 4(3): p. 250-5.
38. Smith, P.C., et al., Interleukin-6 and prostate cancer progression. Cytokine Growth Factor Rev, 2001. 12(1): p. 33-40.
39. Rutkowski, P., et al., Cytokine serum levels in soft tissue sarcoma patients: correlations with clinico-pathological features and prognosis. Int J Cancer, 2002. 100(4): p. 463-71.
40. Kallio, J.P., et al., Soluble immunological parameters and early prognosis of renal cell cancer patients. J Exp Clin Cancer Res, 2001. 20(4): p. 523-8.
41. Ljungberg, B., K. Grankvist, and T. Rasmuson, Serum interleukin-6 in relation to acute-phase reactants and survival in patients with renal cell carcinoma. Eur J Cancer, 1997. 33(11): p. 1794-8.
42. Fearon, K.C., et al., Pancreatic cancer as a model: inflammatory mediators, acute-phase response, and cancer cachexia. World J Surg, 1999. 23(6): p. 584-8.
43. McMillan, D.C., et al., Albumin concentrations are primarily determined by the body cell mass and the systemic inflammatory response in cancer patients with weight loss. Nutr Cancer, 2001. 39(2): p. 210-3.
44. Oya, M., et al., High preoperative plasma D-dimer level is associated with advanced tumor stage and short survival after curative resection in patients with colorectal cancer. Jpn J Clin Oncol, 2001. 31(8): p. 388-94.
45. Ferrigno, D., G. Buccheri, and I. Ricca, Prognostic significance of blood coagulation tests in lung cancer. Eur Respir J, 2001. 17(4): p. 667-73.
46. Blackwell, K., et al., Plasma D-dimer levels in operable breast cancer patients correlate with clinical stage and axillary lymph node status. J Clin Oncol, 2000. 18(3): p. 600-8.
47. Tabuchi, T., et al., Granulocyte apheresis as a possible new approach in cancer therapy: A pilot study involving two cases. Cancer Detect Prev, 1999. 23(5): p. 417-21.
48. Oberholzer, A., C. Oberholzer, and L.L. Moldawer, Sepsis syndromes: understanding the role of innate and acquired immunity. Shock, 2001. 16(2): p. 83-96.
49. Heidecke, C.D., et al., Selective defects of T lymphocyte function in patients with lethal intraabdominal infection. Am J Surg, 1999. 178(4): p. 288-92.
50. Elgert, K.D., D.G. Alleva, and D.W. Mullins, Tumor-induced immune dysfunction: the macrophage connection. J Leukoc Biol, 1998. 64(3): p. 275-90.
51. De la Fuente, M. and V.M. Victor, Ascorbic acid and N-acetylcysteine improve in vitro the function of lymphocytes from mice with endotoxin-induced oxidative stress. Free Radic Res, 2001. 35(1): p. 73-84.
52. Malmberg, K.J., et al., A short-term dietary supplementation of high doses of vitamin E increases T helper 1 cytokine production in patients with advanced colorectal cancer. Clin Cancer Res, 2002. 8(6): p. 1772-8.
53. Heller, A.R., et al., N-acetylcysteine reduces respiratory burst but augments neutrophil phagocytosis in intensive care unit patients. Crit Care Med, 2001. 29(2): p. 272-6.
54. Van Schooten, F.J., et al., Effects of oral administration of N-acetyl-L-cysteine: a multi-biomarker study in smokers. Cancer Epidemiol Biomarkers Prev, 2002. 11(2): p. 167-75.
55. Albini, A., et al., Inhibition of angiogenesis-driven Kaposi's sarcoma tumor growth in nude mice by oral N-acetylcysteine. Cancer Res, 2001. 61(22): p. 8171-8.

Social & Bookmarking:Digg 'De-repression of Anti-Cancer Immunity by N-Acetylcysteine' Add 'De-repression of Anti-Cancer Immunity by N-Acetylcysteine' to Add 'De-repression of Anti-Cancer Immunity by N-Acetylcysteine' to Technorati Stumble 'De-repression of Anti-Cancer Immunity by N-Acetylcysteine' Add 'De-repression of Anti-Cancer Immunity by N-Acetylcysteine' to Furl Add 'De-repression of Anti-Cancer Immunity by N-Acetylcysteine' to Reddit Add 'De-repression of Anti-Cancer Immunity by N-Acetylcysteine' to Blinklist Add 'De-repression of Anti-Cancer Immunity by N-Acetylcysteine' to Ma.gnolia Share 'De-repression of Anti-Cancer Immunity by N-Acetylcysteine' on Facebook Add 'De-repression of Anti-Cancer Immunity by N-Acetylcysteine' to Google Add 'De-repression of Anti-Cancer Immunity by N-Acetylcysteine' to Yahoo Web 

Add Comment

You must be signed-in to add your comments.

now or Join the Community for free.

Home | News | Patents | Products | Jobs | Links | Search | Journal | RSS

About | Advisory Board | Newsletter | Advertise | Contact | Sitemap | Privacy Policy | Terms of Use

Copyright © 2006 - 2024 - All rights reserved. - Toronto Web Design V2.04

Stouffville Concrete | Tottenham Concrete | Uxbridge Concrete | Gerogetown Concrete | Rockwood Concrete | Kleinburg Concrete | Stouffville Real Estate Agent