Effect of PTEN gene overexpression on cell cycle and tumor invasion in a human ovarian carcinoma SKOV3 cell line

AIM:To investigate the role of phosphatase and tensin homology deleted on chromosome(PTEN) gene in the cell cycle and invasion ability of human ovarian carcinoma SKOV3 cell line in vitro. METHODS:Human ovarian carcinoma SKOV3 cells were transfected with a eukaryotic expression plasmid vector containing PTEN gene in vitro,and then the positive cell clones were selected and amplified. MTT method was used to observe the inhibitory rate,flow cytometry was used to detect the cycle of transfected PTEN cells and apoptosis level. Western blotting analysis was used to determine PTEN gene expression. The invasiveness of transfected cells were measured quantitatively by Matrigel invasion assays (Transwell chamber). RESULTS:The expression of PTEN mRNA in SKOV3 cells increased after transfection with PTEN gene. Flow cytometry showed that the percentage of cells in S phase increased,but that in G₂/M phase decreased. Invasiveness of SKOV3 was significantly decreased. CONCLUSION:The transfection of PTEN gene into SKOV3 cells can inhibit human ovarian carcinoma SKOV3 cell proliferation,invasion and induce SKOV3 cell apoptosis.     

Apoptosis and expression of apoptosis-related genes in kidneys of the rats with 5/6 nephrectomy

AIM: To establish a model of subtotal nephrectomy (SNx) and investigate the changes of apoptosis and apoptosis-related genes (Bax, bcl-2, caspase-3, caspase-8 and caspase-9) in the rat remnant kidney. METHODS: Remnant kidneys were produced in adult male SD rats by 5/6 nephrectomy. The renal function and histopathological changes were evaluated at 1, 2, 4, 8, 12, 16, 26 and 40 weeks after operation. The tissues of remnant kidneys were collected to detect apoptosis cells by in situ end-labeling of cleaved DNA (TUNEL) and proliferating cells by determining the proliferating cell nuclear antigen (PCNA). The expression of Bax, bcl-2, caspase-3, caspase-8 and caspase-9 was measured by RT-PCR and Western blotting. The proteins were detected by immunohistochemistry staining. The relation between apoptosis, proliferation, glomerulosclerosis and renal interstitial fibrosis was also observed. RESULTS: The results showed the renal pathological dynamic changes in 5/6 nephrectomy remnant kidneys were tubule-interstitial inflammation and fibrosis, as well as glomerulosclerosis. There were transient increases in both proliferating and apoptotic processes in glomerulus, tubules and interstitium. Apoptosis was increased and most of apoptotic cells were detected in tubular epithelial cells and interstitial area. The mRNA and protein expression of Bax, caspase-3, caspase-8 and caspase-9 were increased in all course, and peaked at week 4 and 40 in the SNX rats. The successive changes of these parameters were parallel to the level of focal inflammation in interstitium. Glomerulosclerosis index was related with focal inflammation cells and 24 hours urine protein (r=0.788, 0.822; P<0.01). The tubuler apoptosis index was related with Scr, BUN, 24 hours urine protein and focal inflammation cells (r=0.824, 0.794, 0.883, 0.948; P<0.01). The mRNA and protein expression of Bcl-2 was not significantly increased than those in control rats. CONCLUSION: Apoptosis may be involved in the development of chronic renal damaged in 5/6 nephrectomy and play an important role in chronic glomerulosclerosis, tubule atrophy and interstitial fibrosis. The renal interstitial inflammation may promote the apoptosis in the remnant kidney.     

Effects of DARPP-32 on the drug sensitivity of SH-SY5Y cells

AIM: To investigate the effects of DARPP-32 on the drug sensitivity of human neuroblastoma cell line SH-SY5Y. METHODS: The plasmid containing cDNA of DARPP-32 gene and the small interfering RNA eukaryotic expression vector specific to human DARPP-32 gene were constructed and transfected into SH-SY5Y cells. Stable transfectants were identified by RT-PCR and Western blotting analysis. MTT assay and flow cytometry assay were used to investigate the effects of DARPP-32 on the drug sensitivity and the drug accumulation in cell models. The expressions of Bcl-2，Bax, P-gp and MRP were analyzed by RT-PCR and Western blotting. RESULTS: The stable clones with increased or decreased DARPP-32 expression were successfully established. Up-regulation of DARPP-32 significantly enhanced the drug sensitivity and the drug accumulation of SH-SY5Y cells due to down-regulation of P-gp and Bcl-2 expressions. Down-regulation of DARPP-32 significantly reduced the drug sensitivity of SH-SY5Y cells and decreased drug accumulation in SH-SY5Y cells. CONCLUSION: DARPP-32 might mediate the sensitivity of SH-SY5Y cells to conventional chemotherapeutic agents.     

Change of chemosensitivity and mechanisms of human radioresistance esophageal carcinoma cells before and after induction by radiation

AIM: To investigate the change of chemosensitivity of esophageal carcinoma cells before and after induction by radiation,and to detect the excision repair cross complementation group 1 (ERCC1) gene before and after induction,and further to analyze the relationship between ERCC1 expression and chemosensitivity.METHODS: The esophageal carcinoma cell EC9706 was radiated repeatedly by a long-term,intermittent ［60Co］-γ radiation to induce the radioresistance esophageal carcinoma cell EC9706-R.The IC₅₀ and resistant index (RI) of EC9706 and EC9706-R were detected by MTT assay.The expression of ERCC1 was examined by immunocytochemistry and RT-PCR.RESULTS: The IC₅₀ of EC9706 and EC9706-R cells to cisplatin were (1.480±0.012) mg/L and (1.836±0.008) mg/L,respectively (P<0.05),and the RI was 1.240±0.015.The tinctorial scores of ERCC1 protein in EC9706 and EC9706-R were 2.838±0.055 and 2.898±0.039 (P>0.05),and the relatively quantities (IDV) of ERCC1 mRNA in EC9706 and EC9706-R cells were 1.168±0.068 and 1.143±0.089 (P>0.05).SP and RT-PCR did not display visible difference in protein level and mRNA level.CONCLUSION: The chemosensitivity of EC9706-R cells to cisplatin is decreased compared with EC9706 cells,but ERCC1 expression does not change with the radioresistance and chemoresistance.     

Study on hyper methylation of p15INK4B gene in multiple myeloma

AIM: To study the characteristics and regulations of p15 (MST INK4B) methylation in multiple myeloma (MM). METHODS: Method of methylation-specific PCR was applied in 23 cases of MM about the methylation rate of p15 gene. RESULTS: Methyaltion rate in MM was 73.5%(17/23). The PCR product was a fragment of 148 bp. In four stageⅠcases of MM with plasma cell-typed bone marrow profile, p15^INK4B gene was non-methylated; In one case of stag ⅡMM and one case of stage Ⅲ MM with mature plasma typed bone marrow profile, p15^INK4B gene was no-methylated, too, while in many cases of stageⅠ、stage Ⅱand stage Ⅲ with naive plasma cell in bone marrow profile which were plasma cell-typed or mixed typed, p15^INK4B gene methylation was frequently detected. The methylation rates for stageⅠ、stage Ⅱand stage Ⅲ MM were respectively 55%(5/9),100%(7/7) and 71.4%(5/7). CONCLUSION: p15 gene methylation was a possible pathogenic factor,and might be related to the progression and prognosis of the disease.     

The expression of 53BP1 and 53BP2 gene in nasopharyngeal carcinoma

AIM:To investigate the expression map of two p53 binding proteins 53BP1 and 53BP2 in nasopharyngeal carcinoma (NPC) tissue. METHODS:The expression of 53BP1 and 53BP2 mRNA in NPC biopsy and control group are tested by RT-PCR. The expression of two mRNA in NPC paraffin section are examined by in situ hybridization. RESULTS:No expression of 53BP1 mRNA was found in NPC tissue and control group. However, expression of 53BP2 was detected in NPC biopsy and control group by RT-PCR, specific expressoin found cancerous nest in NPC paraffin section by in situ hybridization. CONCLUSION:The high expression of 53BP2 may be related to the development of NPC.     

Study on mutation of mitochondrial gene from rat breast cancer

AIM: To know the variations of the cytochrome b gene in cancer tissue, paracarinoma tissue and normal tissue and to inquire into the relationship between mutations of mitochondrial genome and carcinogenesis. METHODS: Cellular total DNA was extracted.The cytochrome b genes of three tissues were amplifyed with polymerase chain reaction(PCR). PCR products were analysed by DNA auto-sequencing method. RESULTS: The cytochrome b gene of cancer tissue had the C to G mutation at nt 14931, the C to G mutation at nt 15004 and the T to C mutation at nt15435,respectively. The cytochrome b gene of paracarinoma tissue had the A to C mutation at nt 15436. The cytochrome b gene of normal tissue had not mutation. CONCLUSION:Mitochondrial DNA mutations could be the endogenous factors that induce nuclear genome mutation. It could promoto carcinogenesis. The paracarinoma tissue was abnormal in DNA molecular level.     

Recent advances in artrial elastin

The elastin has been investigated since the 1950s, and it has been found that elastin relates to the vascular diseases in recent years. In this review, the elastin gene structure, distribution and its role in the pathogenesis of vascular diseases and aging are summarized.     

Three kinds of antisense oligodeoxynucleotide enhance the sensitivity of leukemia cell K562 to cisplatin

AIM: To investigate whether antisense oligodeoxynucleotides of hTERT、bcl-2 and c-myc could enhance the sensitivity of leukemia cell K562 to cisplatin. METHODS: The inhibiting effects of cisplatin and cisplatin plus antisense oligodeoxynucleotide on K562 cells were determined by MTT. RESULTS: The inhibiting rate of 20 μmol/L cisplatin to K562 cell is 17.17%±1.36% and it becomes 25.41%±1.77%, 26.18%±1.43% and 28.29%±1.05%, respectively, as combinated with antisense oligodeoxynucleotide of hTERT, bcl-2 or c-myc. CONCLUSION: These results indicated that antisense oligodeoxynucleotides of hTERT, bcl-2 and c-myc enhanced efficacy of cisplatin in K562 leukemic cells.