Relationship between tumor-associated macrophage subsets and CD47 expression in squamous cell carcinoma of the head and neck in the tumor microenvironment.
Tumor-associated macrophages (TAM) have been classified into an immunostimulatory M1 subset against microbes and malignancies, and an immunoregulatory M2 subset that secretes immunosuppressive cytokines in order to repair tissues damaged by malignancies. The infiltration of M2 in the tumor microenvironment is known to facilitate immunosuppression and tumor-promoting properties. In the present study, we investigated the phagocytic potential of these macrophage subsets in oral squamous cell carcinoma (OSCC) in relation to the expression of CD47, the 'don't eat me' signal against macrophages. The macrophage subsets M1 (induced by GM-CSF and IFN-γ) and M2 (induced by M-CSF and IL-10) were derived from the CD14(+) cells of healthy donors. Phagocytosis of the CFSE-labeled CD47(+) cell line HSC-3 by M1/M2 was assessed using flow cytometry and suppressed by an anti-CD47 neutralizing antibody or CD47 siRNA. Furthermore, CD68(+) and CD163(+) macrophage subset counts infiltrating tumor tissue and the expression of CD47 on cancer cells were examined immunohistochemically in 74 cases of OSCC, and their relationships with clinicopathological parameters or prognoses were determined. The phagocytic potential of M1 was similar to that of M2 in vitro. Phagocytosis by M1 increased in a CD47-dependent manner by the neutralizing antibody and siRNA, but did not in M2. An immunohistochemical (IHC) analysis revealed that the expression of CD47 did not correlate with macrophage subsets in peritumoral tissue or with any clinicopathological parameters; however, the stronger expression of CD47 by cancer cells and larger number of total macrophages/M2 were independently related to shorter survivals. Our results suggest that the expression of CD47 by cancer cells is related to evasion from phagocytosis, particularly that by M1 in vitro. IHC results indicate that various mechanisms are involved in the engulfing potential of TAM subsets in vivo.
Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
Koichi
K
Sakakura
Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
Hideyuki
H
Takahashi
Department of Oncology Clinical Development, Gunma University Graduate School of Medicine, Gunma, Japan.
Kyoichi
K
Kaira
Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
Minoru
M
Toyoda
Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
Takaaki
T
Murata
Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, Gunma, Japan.
Hiroshi
H
Ohnishi
Department of Diagnostic Pathology, Gunma University Graduate School of Medicine, Gunma, Japan.
Tetsunari
T
Oyama
Department of Otolaryngology-Head and Neck Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
Kazuaki
K
Chikamatsu
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D051928:CD47 Antigen / Q000235:genetics / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002452:Cell Count; D045744:Cell Line, Tumor; D005260:Female; D006258:Head and Neck Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008264:Macrophages / Q000145:classification / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015999:Multivariate Analysis; D010587:Phagocytosis; D034622:RNA Interference; D011956:Receptors, Cell Surface / Q000378:metabolism; D059016:Tumor Microenvironment; D000098902:CD163 Antigen; D000097382:CD68 Molecule
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D051928:CD47 Antigen; D011956:Receptors, Cell Surface; D000098902:CD163 Antigen; C497894:CD47 protein, human; C067980:CD68 antigen, human; D000097382:CD68 Molecule