Prognostic impact of reduced connexin43 expression and gap junction coupling of neoplastic stromal cells in giant cell tumor of bone.
Missense mutations of the GJA1 gene encoding the gap junction channel protein connexin43 (Cx43) cause bone malformations resulting in oculodentodigital dysplasia (ODDD), while GJA1 null and ODDD mutant mice develop osteopenia. In this study we investigated Cx43 expression and channel functions in giant cell tumor of bone (GCTB), a locally aggressive osteolytic lesion with uncertain progression. Cx43 protein levels assessed by immunohistochemistry were correlated with GCTB cell types, clinico-radiological stages and progression free survival in tissue microarrays of 89 primary and 34 recurrent GCTB cases. Cx43 expression, phosphorylation, subcellular distribution and gap junction coupling was also investigated and compared between cultured neoplastic GCTB stromal cells and bone marow stromal cells or HDFa fibroblasts as a control. In GCTB tissues, most Cx43 was produced by CD163 negative neoplastic stromal cells and less by CD163 positive reactive monocytes/macrophages or by giant cells. Significantly less Cx43 was detected in α-smooth muscle actin positive than α-smooth muscle actin negative stromal cells and in osteoclast-rich tumor nests than in the adjacent reactive stroma. Progressively reduced Cx43 production in GCTB was significantly linked to advanced clinico-radiological stages and worse progression free survival. In neoplastic GCTB stromal cell cultures most Cx43 protein was localized in the paranuclear-Golgi region, while it was concentrated in the cell membranes both in bone marrow stromal cells and HDFa fibroblasts. In Western blots, alkaline phosphatase sensitive bands, linked to serine residues (Ser369, Ser372 or Ser373) detected in control cells, were missing in GCTB stromal cells. Defective cell membrane localization of Cx43 channels was in line with the significantly reduced transfer of the 622 Da fluorescing calcein dye between GCTB stromal cells. Our results show that significant downregulation of Cx43 expression and gap junction coupling in neoplastic stromal cells are associated with the clinical progression and worse prognosis in GCTB.
1st Department of Pathology & Experimental Cancer Research, Semmelweis University Budapest, Hungary.
Peter
P
Balla
1st Department of Pathology & Experimental Cancer Research, Semmelweis University Budapest, Hungary; Department of Neuroradiology, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany.
Mate Elod
ME
Maros
1st Department of Pathology & Experimental Cancer Research, Semmelweis University Budapest, Hungary.
Gabor
G
Barna
Department of Orthopaedics, Semmelweis University, Budapest, Hungary.
Imre
I
Antal
1st Department of Pathology & Experimental Cancer Research, Semmelweis University Budapest, Hungary.
Gergo
G
Papp
1st Department of Pathology & Experimental Cancer Research, Semmelweis University Budapest, Hungary.
Zoltan
Z
Sapi
Department of Pathology, Nuffield Orthopaedic Centre, University of Oxford, Oxford, United Kingdom.
Nicholas Anthony
NA
Athanasou
Laboratory of Experimental Oncology, Institute of Orthopaedics Rizzoli, Bologna, Italy.
Maria Serena
MS
Benassi
Laboratory of Experimental Oncology, Institute of Orthopaedics Rizzoli, Bologna, Italy.
Pierro
P
Picci
1st Department of Pathology & Experimental Cancer Research, Semmelweis University Budapest, Hungary; Hunragian Academy of Sciences-Semmelweis University (MTA-SE) Tumor Progression Research Group, Budapest, Hungary.
Tibor
T
Krenacs
D000199:Actins / Q000235:genetics / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D000469:Alkaline Phosphatase / Q000172:deficiency / Q000235:genetics; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000235:genetics / Q000378:metabolism; D001854:Bone Marrow Cells / Q000378:metabolism / Q000473:pathology; D001859:Bone Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D001842:Bone and Bones / Q000378:metabolism* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D018031:Connexin 43 / Q000235:genetics* / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism* / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D018212:Giant Cell Tumor of Bone / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D015726:Giant Cells / Q000378:metabolism / Q000473:pathology; D006412:Hematopoietic Stem Cells / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged; D009000:Monocytes / Q000378:metabolism / Q000473:pathology; D014411:Neoplastic Stem Cells / Q000378:metabolism* / Q000473:pathology; D061251:Primary Cell Culture; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D016019:Survival Analysis; D000098902:CD163 Antigen
C541116:ACTA2 protein, human; D000199:Actins; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D000098902:CD163 Antigen; D018031:Connexin 43; C500216:GJA1 protein, human; D011956:Receptors, Cell Surface; D000469:Alkaline Phosphatase