The hyposensitive N187D P2X7 mutant promotes malignant progression in nude mice.
Nucleotides are new players in the intercellular communication network. P2X7 is a member of the P2X family of receptors, which are ATP-gated plasma membrane ion channels with diverse biological functions. Abnormal expression and dysfunction of P2X7 have been reported in leukemias. Here, we report a new P2X7 mutant (an A(559)-to-G substitution causing N187D P2X7) cloned from J6-1 leukemia cells. The characteristics of N187D P2X7 were studied by establishing stably transfected K562 cell lines. Our results show that N187D P2X7 required a higher concentration of agonist for its activation, leading to Ca(2+) influx (EC(50) = 293.3 ± 6.6 μm for the mutant and 93.6 ± 2.2 μm for wild-type P2X7) and ERK phosphorylation, which were not caused by differential cell-surface expression or related to high ATPase activity on the cell surface and in the extracellular space. K562 cells expressing this N187D mutant showed a proliferative advantage and reduced pro-apoptosis effects in vitro and in vivo. Furthermore, elevated angiogenesis and CD206-positive macrophage infiltration were found in tumor tissues formed by K562-M cells. In addition, higher expression of VEGF and MCP1 could be detected in tumor tissues formed by K562-M cells. Our results suggest that N187D P2X7, representing mutants hyposensitive to agonist, might be a positive regulator in the progression of hematopoietic malignancies.
Chong
Jing-Hui
JH
State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 288 Nanjing Road, Tianjin 300020, China.
Zheng
Guo-Guang
GG
Ma
Yuan-Yuan
YY
Zhang
Hai-Yan
HY
Nie
Kun
K
Lin
Yong-Min
YM
Wu
Ke-Fu
KF
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D045744:Cell Line, Tumor; D018450:Disease Progression; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D020014:K562 Cells; D007942:Leukemia, Experimental / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D020125:Mutation, Missense; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D058486:Receptors, Purinergic P2X7 / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014183:Transplantation, Heterologous; D047368:Tumor Burden / Q000235:genetics; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D058486:Receptors, Purinergic P2X7; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; D000255:Adenosine Triphosphate; D048051:p38 Mitogen-Activated Protein Kinases; D002118:Calcium