Cancer immunology

Cancer immunology is an interdisciplinary branch of biology that is concerned with understanding the role of the immune system in the progression and development of cancer; the most well known application is cancer immunotherapy, which utilises the immune system as a treatment for cancer.[1]

Cancer immunosurveillance and immunoediting is based on (i) protection against development of spontaneous and chemically induced tumors in animal systems and (ii) identification of targets for immune recognition of human cancer.[2]

Immunosurveillance

Cancer immunosurveillance is a theory formulated in 1957 by Burnet and Thomas, who proposed that lymphocytes act as sentinels in recognizing and eliminating continuously arising, nascent transformed cells.[2][3] Cancer immunosurveillance appears to be an important host protection process that decreases cancer rates through inhibition of carcinogenesis and maintaining of regular cellular homeostasis.[4] It has also been suggested that immunosurveillance primarily functions as a component of a more general process of cancer immunoediting.[2]

Immunoediting

Immunoediting induces selection for certain tumour cells, which loose dominant tumour-specific antigens allowing for tumour progression. It has three main phases: elimination, equilibrium and escape.[5]

Elimination

The elimination phase consists of the following four phases:

The first phase of elimination involves the initiation of an antitumor immune response. Cells of the innate immune system recognize the presence of a growing tumor which has undergone stromal remodeling, causing local tissue damage. This is followed by the induction of inflammatory signals which is essential for recruiting cells of the innate immune system (e.g. natural killer cells, natural killer T cells, macrophages and dendritic cells) to the tumor site. During this phase, the infiltrating lymphocytes such as the natural killer cells and natural killer T cells are stimulated to produce IFN-gamma.

In the second phase of elimination, newly synthesized IFN-gamma induces tumor death (to a limited amount) as well as promoting the production of chemokines CXCL10, CXCL9 and CXCL11. These chemokines play an important role in promoting tumor death by blocking the formation of new blood vessels. Tumor cell debris produced as a result of tumor death is then ingested by dendritic cells, followed by the migration of these dendritic cells to the draining lymph nodes. The recruitment of more immune cells also occurs and is mediated by the chemokines produced during the inflammatory process.

In the third phase, natural killer cells and macrophages transactivate one another via the reciprocal production of IFN-gamma and IL-12. This again promotes more tumor killing by these cells via apoptosis and the production of reactive oxygen and nitrogen intermediates. In the draining lymph nodes, tumor-specific dendritic cells trigger the differentiation of Th1 cells which in turn facilitates the development of cytotoxic CD8+ T cells also known as killer T-cells.

In the final phase of elimination, tumor-specific CD4+ and CD8+ T cells home to the tumor site and the cytotoxic T lymphocytes then destroy the antigen-bearing tumor cells which remain at the site.

Equilibrium and escape

Tumor cell variants which have survived the elimination phase enter the equilibrium phase. In this phase, lymphocytes and IFN-gamma exert a selection pressure on tumor cells which are genetically unstable and rapidly mutating. Tumor cell variants which have acquired resistance to elimination then enter the escape phase.

In the escape phase, tumor cells continue to grow and expand in an uncontrolled manner and may eventually lead to malignancies. In the study of cancer immunoediting, knockout mice have been used for experimentation since human testing is not possible.[2] Tumor infiltration by lymphocytes is seen as a reflection of a tumor-related immune response.[6] There is increasing evidence that biological vesicles (e.g., exosomes) secreted by tumour cells help to foster an immunosuppressive tumour microenvironment.[7]

Cancer immunology and chemotherapy

Obeid et al.[8] investigated how inducing immunogenic cancer cell death ought to become a priority of cancer chemotherapy. He reasoned, the immune system would be able to play a factor via a ‘bystander effect’ in eradicating chemotherapy-resistant cancer cells.[9][10][11] However, extensive research is still needed on how the immune response is triggered against dying tumour cells.[12]

Professionals in the field have hypothesized that ‘apoptotic cell death is poorly immunogenic whereas necrotic cell death is truly immunogenic’.[13][14][15] This is perhaps because cancer cells being eradicated via a necrotic cell death pathway induce an immune response by triggering dendritic cells to mature, due to inflammatory response stimulation.[16][17] On the other hand, apoptosis is connected to slight alterations within the plasma membrane causing the dying cells to be attractive to phagocytic cells.[18] However, numerous animal studies have shown the superiority of vaccination with apoptotic cells, compared to necrotic cells, in eliciting anti-tumor immune responses.[19][20][21][22][23]

Thus Obeid et al.[8] propose that the way in which cancer cells die during chemotherapy is vital. Anthracyclins produce a beneficial immunogenic environment. The researchers report that when killing cancer cells with this agent uptake and presentation by antigen presenting dendritic cells is encouraged, thus allowing a T-cell response which can shrink tumours. Therefore, activating tumour-killing T-cells is crucial for immunotherapy success.[24]

However, advanced cancer patients with immunosuppression have left researchers in a dilemma as to how to activate their T-cells. The way the host dendritic cells react and uptake tumour antigens to present to CD4+ and CD8+ T-cells is the key to success of the treatment.[25]

The role of viruses in cancer development

Various strains of human papillomavirus (HPV) have been found to play an important role in the development of cervical cancer. The HPV oncogenes E6 and E7 that these viruses possess have been shown to immortalise some human cells and thus promote cancer development.[26] Although these strains of HPV have not been found in all cervical cancers, they have been found to be the cause in roughly 70% of cases. The study of these viruses and their role in the development of various cancers is still continuing, however a vaccine has been developed that can prevent infection of certain HPV strains, and thus prevent those HPV strains from causing cervical cancer, and possibly other cancers as well.

A virus that has been shown to cause breast cancer in mice is mouse mammary tumor virus.[27][28] It is from discoveries such as this and the role of HPV in cervical cancer development that research is currently being undertaken to discover whether or not human mammary tumour virus is a cause of breast cancer in humans.[29]

See also

References

  1. ↑ Miller, Jacques F. A. P.; Sadelain, Michel (2015-04-13). "The journey from discoveries in fundamental immunology to cancer immunotherapy". Cancer Cell. 27 (4): 439–449. ISSN 1878-3686. PMID 25858803. doi:10.1016/j.ccell.2015.03.007.
  2. 1 2 3 4 Dunn GP, Bruce AT, Ikeda H, Old LJ, Schreiber RD (Nov 2002). "Cancer immunoediting: from immunosurveillance to tumor escape". Nature Immunology. 3 (11): 991–8. PMID 12407406. doi:10.1038/ni1102-991.
  3. ↑ Burnet M (Apr 1957). "Cancer; a biological approach. I. The processes of control". British Medical Journal. 1 (5022): 779–86. JSTOR 25382096. PMC 1973174 Freely accessible. PMID 13404306. doi:10.1136/bmj.1.3356.779.
  4. ↑ Kim R, Emi M, Tanabe K (May 2007). "Cancer immunoediting from immune surveillance to immune escape". Immunology. 121 (1): 1–14. PMC 2265921 Freely accessible. PMID 17386080. doi:10.1111/j.1365-2567.2007.02587.x.
  5. ↑ Dunn GP, Old LJ, Schreiber RD (2004). "The three Es of cancer immunoediting". Annual Review of Immunology. 22: 329–60. PMID 15032581. doi:10.1146/annurev.immunol.22.012703.104803.
  6. ↑ Odunsi K, Old LJ (2007). "Tumor infiltrating lymphocytes: indicators of tumor-related immune responses". Cancer Immunity. 7: 3. PMC 2935754 Freely accessible. PMID 17311362.
  7. ↑ Syn, Nicholas; Wang, Lingzhi; Sethi, Gautam; Thiery, Jean-Paul; Goh, Boon-Cher (2016-07-01). "Exosome-Mediated Metastasis: From Epithelial-Mesenchymal Transition to Escape from Immunosurveillance". Trends in Pharmacological Sciences. 37 (7): 606–617. ISSN 1873-3735. PMID 27157716. doi:10.1016/j.tips.2016.04.006.
  8. 1 2 Obeid M, Tesniere A, Ghiringhelli F, Fimia GM, Apetoh L, Perfettini JL, Castedo M, Mignot G, Panaretakis T, Casares N, Métivier D, Larochette N, van Endert P, Ciccosanti F, Piacentini M, Zitvogel L, Kroemer G (Jan 2007). "Calreticulin exposure dictates the immunogenicity of cancer cell death". Nature Medicine. 13 (1): 54–61. PMID 17187072. doi:10.1038/nm1523.
  9. ↑ Steinman RM, Mellman I (Jul 2004). "Immunotherapy: bewitched, bothered, and bewildered no more". Science. 305 (5681): 197–200. PMID 15247468. doi:10.1126/science.1099688.
  10. ↑ Lake RA, van der Most RG (Jun 2006). "A better way for a cancer cell to die". The New England Journal of Medicine. 354 (23): 2503–4. PMID 16760453. doi:10.1056/NEJMcibr061443.
  11. ↑ Zitvogel L, Tesniere A, Kroemer G (Oct 2006). "Cancer despite immunosurveillance: immunoselection and immunosubversion". Nature Reviews. Immunology. 6 (10): 715–27. PMID 16977338. doi:10.1038/nri1936.
  12. ↑ Zitvogel L, Casares N, Péquignot MO, Chaput N, Albert ML, Kroemer G (2004). "Immune response against dying tumor cells". Advances in Immunology. Advances in Immunology. 84: 131–79. ISBN 978-0-12-022484-5. PMID 15246252. doi:10.1016/S0065-2776(04)84004-5.
  13. ↑ Bellamy CO, Malcomson RD, Harrison DJ, Wyllie AH (Feb 1995). "Cell death in health and disease: the biology and regulation of apoptosis". Seminars in Cancer Biology. 6 (1): 3–16. PMID 7548839. doi:10.1006/scbi.1995.0002.
  14. ↑ Thompson CB (Mar 1995). "Apoptosis in the pathogenesis and treatment of disease". Science. 267 (5203): 1456–62. PMID 7878464. doi:10.1126/science.7878464.
  15. ↑ Igney FH, Krammer PH (Apr 2002). "Death and anti-death: tumour resistance to apoptosis". Nature Reviews. Cancer. 2 (4): 277–88. PMID 12001989. doi:10.1038/nrc776.
  16. ↑ Steinman RM, Turley S, Mellman I, Inaba K (Feb 2000). "The induction of tolerance by dendritic cells that have captured apoptotic cells". The Journal of Experimental Medicine. 191 (3): 411–6. PMC 2195815 Freely accessible. PMID 10662786. doi:10.1084/jem.191.3.411.
  17. ↑ Liu K, Iyoda T, Saternus M, Kimura Y, Inaba K, Steinman RM (Oct 2002). "Immune tolerance after delivery of dying cells to dendritic cells in situ". The Journal of Experimental Medicine. 196 (8): 1091–7. PMC 2194037 Freely accessible. PMID 12391020. doi:10.1084/jem.20021215.
  18. ↑ Kroemer G, El-Deiry WS, Golstein P, Peter ME, Vaux D, Vandenabeele P, Zhivotovsky B, Blagosklonny MV, Malorni W, Knight RA, Piacentini M, Nagata S, Melino G (Nov 2005). "Classification of cell death: recommendations of the Nomenclature Committee on Cell Death". Cell Death and Differentiation. 12 Suppl 2: 1463–7. PMID 16247491. doi:10.1038/sj.cdd.4401724.
  19. ↑ Buckwalter MR, Srivastava PK (2013). "Mechanism of dichotomy between CD8+ responses elicited by apoptotic and necrotic cells". Cancer Immunity. 13: 2. PMC 3559190 Freely accessible. PMID 23390373.
  20. ↑ Gamrekelashvili J, Ormandy LA, Heimesaat MM, Kirschning CJ, Manns MP, Korangy F, Greten TF (Oct 2012). "Primary sterile necrotic cells fail to cross-prime CD8(+) T cells". Oncoimmunology. 1 (7): 1017–1026. PMC 3494616 Freely accessible. PMID 23170250. doi:10.4161/onci.21098.
  21. ↑ Janssen E, Tabeta K, Barnes MJ, Rutschmann S, McBride S, Bahjat KS, Schoenberger SP, Theofilopoulos AN, Beutler B, Hoebe K (Jun 2006). "Efficient T cell activation via a Toll-Interleukin 1 Receptor-independent pathway". Immunity. 24 (6): 787–99. PMID 16782034. doi:10.1016/j.immuni.2006.03.024.
  22. ↑ Ronchetti A, Rovere P, Iezzi G, Galati G, Heltai S, Protti MP, Garancini MP, Manfredi AA, Rugarli C, Bellone M (Jul 1999). "Immunogenicity of apoptotic cells in vivo: role of antigen load, antigen-presenting cells, and cytokines". Journal of Immunology. 163 (1): 130–6. PMID 10384108.
  23. ↑ Scheffer SR, Nave H, Korangy F, Schlote K, Pabst R, Jaffee EM, Manns MP, Greten TF (Jan 2003). "Apoptotic, but not necrotic, tumor cell vaccines induce a potent immune response in vivo". International Journal of Cancer. 103 (2): 205–11. PMID 12455034. doi:10.1002/ijc.10777.
  24. ↑ Storkus WJ, Falo LD (Jan 2007). "A 'good death' for tumor immunology". Nature Medicine. 13 (1): 28–30. PMID 17206130. doi:10.1038/nm0107-28.
  25. ↑ Dunn GP, Koebel CM, Schreiber RD (Nov 2006). "Interferons, immunity and cancer immunoediting". Nature Reviews. Immunology. 6 (11): 836–48. PMID 17063185. doi:10.1038/nri1961.
  26. ↑ zur Hausen H (May 2000). "Papillomaviruses causing cancer: evasion from host-cell control in early events in carcinogenesis". Journal of the National Cancer Institute. 92 (9): 690–8. PMID 10793105. doi:10.1093/jnci/92.9.690.
  27. ↑ Brittner, J.J. (1943). "Possible relationship of the oestrogenic hormones, genetic susceptibility and milk influence in the production of mammary cancer in mice". Cancer Research. 2: 710–721.
  28. ↑ Callahan R, Smith GH (Feb 2000). "MMTV-induced mammary tumorigenesis: gene discovery, progression to malignancy and cellular pathways". Oncogene. 19 (8): 992–1001. PMID 10713682. doi:10.1038/sj.onc.1203276.
  29. ↑ Lawson JS, Tran DD, Carpenter E, Ford CE, Rawlinson WD, Whitaker NJ, Delprado W (Dec 2006). "Presence of mouse mammary tumour-like virus gene sequences may be associated with morphology of specific human breast cancer". Journal of Clinical Pathology. 59 (12): 1287–92. PMC 1860546 Freely accessible. PMID 16698952. doi:10.1136/jcp.2005.035907.
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