| Tumor is the result of abnormal proliferation of somatic cells deficient of normal regulation. The deregulation of the cell cycle caused by activation of oncogenes and inactivation of tumor suppressor genes plays a crucial role in the carcinogenesis and development of tumor.Osteosarcoma(OS) is the most common primary malignant tumor of bone, taking up 20% of all such malignancies. It's biological behavior is highly malignant and characterized by swift development and hematogenous metastasis in the early stage. Although the clinical apply of the neoadjuvant chemotherapy and limb-reservable surgery greatly improved the prognosis of the OS patients, OS is still a malignantdisease with the high death rate and deformity rate.The INK4a/ARF (cyclin dependent kinase 4 inhibitor a /alternative reading frame) gene locus maps to 9p21 of the human chromosome. By the alternative reading frame it encodes two tumor suppressor proteins, P16INK4a and P14ARF, involved in the regulation of the cell cycle. P14ARF regulates the cell cycle by means of the P53-pathway and E2F-1-pathway, leads to cell cycle arrest in the Gl phase, and inhibits the cell proliferation. As a tumor suppressor gene, P53 regulates the cell cycle reversely by multiple mechanisms, induces apoptosis, and inhibits the abnormal cell proliferation. E2F-1, a member of the transcription factor family, when activated, induces the expression of its target genes related to DNA synthesis, therefore promotes DNA synthesis and causes the cell proliferation. P14ARF binds to MDM2 and neutralize the MDM2-mediated degradation of P53 so as to stabilize P53 and cause P53 to accumulate in the nucleus to induce the cell cycle arrest or apoptosis.Additionally, P14ARF possesses multiple binding domains to bind to the transcription factor E2F-1 and down-regulates the E2F-l-dependant transcription to prompt cell cycle arrest and induce E2Fl-dependant apoptosis. As a newly-discovered tumor suppressor gene, there are few reports on the united expression of P14ARF and its molecular pathway in human OS.Objective: We performed the immunohistochemistry technique to detect the expression of the P14ARF, P53 and E2F-1 in human OS and analyzed their correlations to evaluate the role they play in the carcinogenesis and development of human OS. We expect that the study will help us to elucidate the carcinogenetic mechanism of human OS and providetheoretic foundation for the diagnosis and genie therapy.Materials and methods: We collected 30 paraffin-embedded human OS specimens from operations and biopsies. All the specimens were affirmed by pathology and classified as three grades based on the grade of differentiation (I grade 8 cases, II grade 12 cases, III grade 10 cases). All the cases were not treated by any radiotherapy or chemotherapy. The control group consisted of 10 paraffin-embedded osteochondroma(OC) specimens. Immunohistochemica] staining with S-P method was performed to exam the expression of P14ARF, P53, and E2F-1 in OS and OC. All the results were analyzed with SPSS 10.0 statistical software. a=0.05 was regarded as the statistical criterion. Results:1. Expression of P14ARF protein: 1.1 The positive immunostaining rate of P14ARF in 10 OCs was 90.0%(9/10), in which negative, weak, moderate and strong positive staining were 1, 3, 4, 2, respectively, The positive immunostaining rate in 30 OSs was 43.3 %(13/30), in which negative, weak, moderate and strong positive staining were 17, 8, 4, 1, respectively. Comparing the positive staining rate and staining intensity between OCs and OSs respectively, there were significant differences (P<0.05). 1.2 In grade I of OSs, the positive immunostaining rate of P14ARF was 75.096(6/8), in which negative, weak, moderate and strong positive staining were 2, 3, 2. 1, respectively. In grade II+IIIof OSs, the positive immunostaining rate of P14ARF was 31.8%(7/22) in which negative, weak and moderate positive staining were 15, 5, 2, respectively. Comparing the positive staining rate and stai...
|
PDF Full Text Request