p50 nuclear factor-κB overexpression in tumor-associated macrophages inhibits M1 inflammatory responses and antitumor resistance

A Saccani, T Schioppa, C Porta, SK Biswas… - Cancer research, 2006 - AACR
A Saccani, T Schioppa, C Porta, SK Biswas, M Nebuloni, L Vago, B Bottazzi, MP Colombo
Cancer research, 2006AACR
Tumor-associated macrophages (TAM) are a major inflammatory infiltrate in tumors and a
major component of the protumor function of inflammation. TAM in established tumors
generally have an M2 phenotype with defective production of interleukin-12 (IL-12) and high
IL-10. Here, we report that defective responsiveness of TAM from a murine fibrosarcoma and
human ovarian carcinoma to M1 activation signals was associated with a massive nuclear
localization of the p50 nuclear factor-κB (NF-κB) inhibitory homodimer. p50 overexpression …
Abstract
Tumor-associated macrophages (TAM) are a major inflammatory infiltrate in tumors and a major component of the protumor function of inflammation. TAM in established tumors generally have an M2 phenotype with defective production of interleukin-12 (IL-12) and high IL-10. Here, we report that defective responsiveness of TAM from a murine fibrosarcoma and human ovarian carcinoma to M1 activation signals was associated with a massive nuclear localization of the p50 nuclear factor-κB (NF-κB) inhibitory homodimer. p50 overexpression inhibited IL-12 expression in normal macrophages. TAM isolated from p50−/− mice showed normal production of M1 cytokines, associated with reduced growth of transplanted tumors. Bone marrow chimeras showed that p50 inactivation in hematopoietic cells was sufficient to result in reduced tumor growth. Thus, p50 NF-κB overexpression accounts for the inability of TAM to mount an effective M1 antitumor response capable of inhibiting tumor growth. (Cancer Res 2006; 66(23): 11432-40)
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