PinX1 regulation of telomerase activity and apoptosis in nasopharyngeal carcinoma cells.
BACKGROUND
Human interacting protein X1 (PinX1) has been identified as a critical telomerase inhibitor and proposed to be a putative tumor suppressor gene. Loss of PinX1 has been found in a large variety of malignancies, however, its function in inhibiting telomerase activity of tumor cells is not well documented. Here we show that PinX1 is essential for down-regulation telomerase activity of nasopharyngeal carcinoma.


METHODS
Expression vectors of human PinX1 (pEGFP-C3-PinX1) and its small interfering RNA (PinX1-FAM-siRNA) were constructed and transfected into NPC. Their effects on mRNA of telomerase catalytic subunit (hTERT), telomerase activity, cell proliferation, cell migration, wound healing, cell cycles and apoptosis were examined using semi-quantitative RT-PCR, stretch PCR, MTT assay, Transwell, scratch assay and flow cytometry, respectively.


RESULTS
Transfection of pEGFP-C3-PinX1 and PinX1-FAM-siRNA increased and reduced PinX1 mRNA by 1.6-fold and 70%, respectively. Over-expression of PinX1 decreased hTERT mRNA by 21%, reduced telomerase activity, inhibited cell growth, migration and wound healing ability, arrested cells in G0/G1 phase, and increased apoptotic index. In contrast, down-regulation of PinX1 did not alter the above characteristics.


CONCLUSIONS
PinX1 may play important roles in NPC proliferation, migration and apoptosis and has application potential in tumor-targeted gene therapy.
Department of Otolaryngology Head and Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
Xiao-Fen
XF
Lai
Cong-Xiang
CX
Shen
Zhong
Z
Wen
Yu-Hong
YH
Qian
Chao-Sheng
CS
Yu
Jun-Qi
JQ
Wang
Ping-Neng
PN
Zhong
Hai-Li
HL
Wang
D017209:Apoptosis / Q000235:genetics*; D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D015972:Gene Expression Regulation, Neoplastic; D005822:Genetic Vectors; D006801:Humans; D009303:Nasopharyngeal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D034741:RNA, Small Interfering / Q000235:genetics; D019098:Telomerase / Q000037:antagonists & inhibitors / Q000235:genetics*; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism; D014945:Wound Healing / Q000235:genetics
D018797:Cell Cycle Proteins; C440808:PINX1 protein, human; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; C509186:TERT protein, human; D019098:Telomerase