Review Article 247 Hemoglobins, Hemorphins, and 11p15.5 Chromosomal Region in Cancer Biology and İmmunity with Special Emphasis for Brain Tumors Meric Adil Altinoz1 Ilhan Elmaci2 Bahri Ince3 Aysel Ozpinar4 Aydin Murat Sav5 1 Department of Immunology, Istanbul University, DETAE - Address for correspondence Meric Adil Altinoz, MD, Department of Experimental Medicine Research Institute, Istanbul, Turkey Immunology, Istanbul University, DETAE - Experimental Medicine 2 Department of Neurosurgery, Memorial Hospital, Istanbul, Turkey Research Institute, Istanbul, Turkey 34300 3 Department of Psychiatry, Bakirkoy Mental Diseases Education and (e-mail: [email protected]). Training Hospital, Istanbul, Turkey 4 Department of Biochemistry, Acibadem University, Istanbul, Turkey 5 Department of Pathology, Acibadem University, Istanbul, Turkey J Neurol Surg A 2016;77:247–257. Abstract In systemic cancers, increased hemolysis leads to extracellular hemoglobin (HB), and experimental studies have shown its provoking role on tumor growth and metastasis. However, investigations have shown that HB chains presented by tumor vascular pericytes or serum protein complexes of HB could also induce antitumor immunity, which may be harnessed to treat refractory cancers and brain tumors. Mounting recent evidence shows that expression of HBs is not restricted to erythrocytes and that HBs exist in the cells of lung and kidney, in macrophages, and in neurons and glia of the central nervous system (CNS). HBs mediate coping with hypoxia and free radical stress in normal and tumor cells, and they are increased in certain tumors including breast, lung, colon, and squamous cell cancers. Recent studies showed HBs in meningioma, in the cyst fluid of craniopharyngioma, in the cerebrospinal fluid (CSF) of pediatric patients with posterior fossa tumors, and in glioblastoma cell lines. Hemorphins, abundant brain peptides formed via HB-chain cleavage, exert opioid activity and antiproliferative and immunomodifier effects. Hence mutations in HBs may modify brain tumorigenesis via influencing hemorphins and perturbing regulations of immune surveillance and cell growth in the neuroectodermal tissues. The β-globin gene cluster resides in the chromosome region 11p15.5, harboring important immunity genes and IGF2, H19, PHLDA2/TSSC3, TRIM3, and SLC22A18 genes associated with cancers and gliomas. 11p15.5 is a prominent region subject to epigenetic regulation. Thus the β-globin loci may exert haplotypal interactions with these. Some clues support this theory. It is well established that iron load induces liver cancer in thalassemia major; however iron Keywords load–independent associations also exist. Enhanced rates of hematologic malignancies ► hemoglobins are associated with HB Lepore, association of hemoglobin E with cholangiocarcinoma, ► brain tumors and enhanced gastric cancer rates in the thalassemia trait. In the African Herero ► 11p15.5 gene cluster population, a mutant form of δ-globin is very prevalent, and this population has higher received © 2016 Georg Thieme Verlag KG DOI http://dx.doi.org/ April 30, 2015 Stuttgart · New York 10.1055/s-0035-1566120. accepted after revision ISSN 2193-6315. August 11, 2015 published online March 2, 2016 248 Novel Pathways of Glial Tumor Formation Altinoz et al. rates of pediatric brain tumors. Globins are also expressed in healthy endothelia and in tumoral vessels, indicating potential involvement in angiogenesis. Studies on HBs and their cleavage peptides in cancers and brain tumors may lead to innovative treatment strategies. Introduction Gower-2 (α2ε2), Portland-1 (ζ2γ2) HB, and HB-F (fetal hemo- globin) (α2γ2). In adults, three HBs exist: the major adult HB- Primary central nervous system (CNS) tumors have gained A(α2β2, 97%) and the minor HBs, HB-A2 (α2δ2, < 3%)11 the attention of researchers for many reasons. In high-grade and HB-F (<0.6%).12 HB-A consists of two α- and two β-globin glial tumors, maximum surgical resection, radiotherapy, and globular chain proteins assembling into a α2β2 heterote- adjuvant temozolomide is the new standard of care. Yet the tramer, where each globin molecule binds a heme prosthetic 13 median survival of patients with glioblastoma multiforme group. In adult HB, the carriage of O2 is mediated via (GBM) is 15 months.1 This outcome is alarmingly poor; binding of the ligand to heme iron. Carbon dioxide is trans- hence deciphering novel pathways of glial tumor formation is ported in the blood in solution and by interactions with the essential to develop better treatments. In other brain tumors aminoterminal residues of HB and not via binding to the that are not as invasive as GBM, patients’ morbidity and heme iron.3 HB is also involved in the generation, transport, mortality after surgical resection are still high due to the and scavenging of NO and its metabolic derivatives.3,14,15 The obvious essentiality of all neural tissues in the CNS. In antioxidant functions of intracellular HB and superoxide and systemic cancers, survival ratios are still far from satisfactory hydrogen peroxide scavenger properties were discovered,9,16 for metastatic disease. and its detoxification of oxidizing radicals yields nontoxic In this review, we discuss hemoglobin (HB) chains, hem- ferric states.17 orphins formed via cleavage of globin chains,2 and the 11p15.5 gene locus pertinent to malignancies with special Tumor-Provoking Roles of Extracellular HBs emphasis on brain tumors. The 11p15.5 is a chromosomal 3 site, where β-globin gene cluster and genes in association To expand in size, tumors must recruit new vessels for O2 and with gliomagenesis reside including IGF-2, H19, TSSC3, TRIM3, nutrient supply.18 Elevation of vascular endothelial growth and SLC22A18. Important genes of immunity also reside factor A (VEGF-A)19 and mechanical stress generated by here,4 and loss of heterozygosity (LOH) events at this site expanding tumor cells result in tortuous vessels18 leading are frequent in high-grade glial tumors.5 Because 11p15.5 is a to an uneven blood flow and lower perfusion within prominent chromosomal site subject to epigenetic regulation tumors.20 However, tumors manage to expand despite insuf- such as imprinting, the β-globin gene cluster and glioma- ficient vascular supply, suggesting other mechanisms of O2 susceptibility genes may exert haplotypal associations. In the delivery. Tumor cells are able to form primitive microvessels – last decade, the presence of HB chains in nonerythroid cells via vasculogenic mimicry (VM),21 23 and highly invasive and their upregulation in malignancies were discovered. tumors line fluid-conducting channels.21 However, an effi- Expressions of HB chains in macrophages,6 lung cells,7,8 renal cient RBC circulation through these channels is problematic mesangium,9 and retinal ganglion cells10 were found, and because these channels exert varying diameters22 and are 21 their roles in oxygen (O2) sensing and protection against free often too small (< 5 µm in diameter). Retraction of endo- radicals were discovered. thelial cell (EC)-lined blood vessels leave empty sleeves composed only of basement membrane24 resembling inver- 23 tebrate vessels. In invertebrates, extraerythrocytic HB-O2 A Short Description of HB Genetics and 25 26 Biochemistry exists and transports O2 through the organism. Although fluid-conducting primitive channels and tumoral vasculo- 27 HBs are heme-containing proteins binding O2,carbonmon- genic mimicry may hamper efficient RBC circulation, they oxide, and nitric oxide (NO). In red blood cells (RBCs), HB may facilitate diffusion of free HB. accounts for 98% of proteins, and during differentiation Hence a four-step process is suggested, where extracellular 28 from reticulocytes, RBCs finish the synthesis of HB before HB contributes to tumoral O2 delivery. First, hemolysis in 2 28 ribosomal degradation. The human α-globin gene cluster tumor vessels generates extraerythrocytic HB-O2. Second, locates on chromosomal region 16p13.3 and includes seven extraerythrocytic HB-O2 is transported within the small loci2:5′- zeta(ζ) – pseudozeta (Ψζ) – mu(µ) – pseudoalpha1 intercellular channels in plasma. Third, within the hypoxic (Ψα1) – α2–α1–theta(θ) – 3′.Thehumanβ-globin gene and acidic tumor environment, extraerythrocytic HB-O2 cluster locates on chromosomal region 11p15.5 and includes delivers O2 to adjacent tumor cells. And finally, the deoxy- five loci2:5′–epsilon(ε) – gammaG (Gγ) – gammaA(Aγ) – genated HB close to the EC-lined tumor vessels deprives delta(δ) – β(β) – 3′. During ontogeny, developing erythro- intraerythrocytic HB-O2 of O2, thus starting a new cycle of 28 blasts sequentially express embryonic Gower-1 (ζ2ε2), O2 transport. It was also demonstrated with experimental Journal of Neurological Surgery—Part A Vol. 77 No. A3/2016 Novel Pathways of Glial Tumor Formation Altinoz et al. 249 29 3þ studies that ECs could uptake free HB, yet it remains to be is in the ferric (Fe ) state, it cannot bind O2. In human blood, shown whether this is relevant for tumor vessels. metHB occurs at trace amounts spontaneously (1 to 2% of total Tumor cells enhance procoagulant activity (PCA) and HB) or at higher levels during oxidizing conditions. NO reacts platelet adhesion on their surface shield cancer antigens to with oxyHB to produce metHB, and most of the metHB in facilitate escape from immune surveillance and reduce their RBCs is derived from this oxidation.3 The metHB is also shear stress–associated death in circulation. Tissue factor (TF) present in solid tumors detectable by MR imaging37