Biomedical subjects

Ke Tang

Publications and source records attributed to Ke Tang.

22 records · Page 2Linked to original sources

PubMed2002

Effects of NPC-associated gene NAG7 on cell cycle and apoptosis in nasopharyngeal carcinoma cells.

BACKGROUND & OBJECTIVE: NPC-associated gene NAG7 was a novel candidate tumor suppressor gene associated with nasopharyngeal carcinoma cloned in our laboratory. This study was designed to investigate the potential effect of NAG7 on the cell cycle and apoptosis of nasopharyngeal carcinoma cell line HNE1 and its molecular mechanism. METHODS: NAG7 gene was introduced into HNE1 cells using lipofectin transfection technique. The expression level of NAG7 gene was analyzed by Northern blot. Cell cycle, cyclins, and cell apoptosis were detected by flow cytometry, and the expressions of cyclin D1 and cyclin E were detected by Western blot. RESULTS: NAG7 gene was re-expressed in NAG7 transfected HNE1 cells. Compared with HNE1 cells and vector transfected HNE1 cells, NAG7 transfected HNE1 cells arrested in G0/G1 phase increased (P < 0.05) and cells in S phase decreased (P < 0.05), the apoptosis cells increased (P < 0.05), and the levels of cyclins of A, B1, D1, and E decreased. Furthermore, the expression of cyclin D1 and E decreased in NAG7 transfected HNE1 cells. CONCLUSION: NAG7 gene re-expression could inhibit overproliferation of NPC cell by delaying the progression of G1 into S in cell cycle and inducing cell apoptosis.

Apoptosis↗

PubMed2002

Analysis of bromodomain of BRD-7 gene and its prokaryotic expression.

BACKGROUND & OBJECTIVE: BRD-7 is a novel gene (AF: 152604), containing a bromodomain, was cloned in our lab. Previous studies showed that BRD-7 plays an obviously suppressive role on NPC cell growth. In order to clarify the function mechanism of this gene, we investigate an important motif of BRD-7, the bromodomain. METHODS: The bromodomain of BRD-7 was analyzed by homology-based amino sequence and secondary structure analysis. In addition, we constructed a prokaryotic expression vector of bromodomain. Western blot analysis was used to confirm the expression of the bromodomain protein in Escherichia coli. RESULTS: Homology-based sequence analysis revealed that the bromodomain of BRD-7 possibly contains four alpha helices (Z, A, B and C), and a hydrophobic pocket which is an important structure to recognize acetylated histone peptide. This bromodomain encoding a 12.8 kD protein, was introduced into Escherichia coli using the pGEX-4T-2 expression vector. After isopropyl beta-D-thiogalactopyranoside(IPTG) induction, a new anticipated protein of 38.8 kD appeared on SDS-PAGE and the result was confirmed by Western blot analysis. CONCLUSION: BRD-7 of bromodomain protein is similar to three proteins containing known structural bromodomain motif by bio-informatics analysis, suggesting the bromodomain of BRD-7 should belong to co-activator subgroup and may have similar function that can selectively interact with acetylated histone peptide.

Amino Acid Sequence↗

PubMed2001

Cloning and Expression Analysis of a Novel Gene, UBAP1, Possibly Involved in Ubiquitin Pathway.

The 9p21-22 region shows loss of heterozygosity in up to 60% of human nasopharyngeal carcinomas (NPC), indicating the presence of a tumor suppressor gene in this region. We have identified a novel minimal common deletion region at 9p21-22. Twenty-two epithelial-derived expressed sequence tags (ESTs) in this critical region were systematically screened by differential RT-PCR to investigate the expression patterns in NPC cell line HNE1 and primary cultures of normal nasopharyngeal epithelial cells. One of these ESTs was found down-expressed in HNE1, whose differential expression was confirmed by Northern blot. Subsequently the corresponding gene sequence for this EST was established by cDNA cloning and RACE procedures (GenBank Accession No.AF222043). Furthermore, a mouse homologueof this gene was identified (GenBank Accession No.AF275549). This gene is 2.7 kb long and contains two UBA domains. It is a new member of UBA domain protein family, encoding a putative protein of 502 amino acids with a theoretical molecular mass of 55 kD, so we have named this gene UBAP1 for ubiquitin associated protein 1 (HUGO Gene Nomenclature Committee-approved symbol). Northern blot and RT-PCR analysis demonstrated a ubiquitous pattern of gene expression in human and mouse tissues. Direct sequencing analysis of the coding region of hUBAP1 following RT-PCR failed to reveal any mutations in a preliminary screening of NPC cell line HNE1 and primary nasopharyngeal carcinomas samples. However, more detailed analysis is to be performed to reveal if fine mutations of this gene are present in NPC.

Journal Article↗

PubMedDate not supplied

Comparative cytotoxicity of high-osmolar and low-osmolar contrast media on HKCs in vitro.

BACKGROUND: Radiocontrast-induced nephropathy is a clinically important complication of intravascularly applied radiocontrast media. A predominant toxic effect of contrast media on renal tubules has been shown in previous clinical trials and animal experiments. Bax and Bcl-2 are members of the Bcl-2 family. Caspases are a family of cell death proteases, caspase-3 is one of the key executioners of apoptosis. In this study, we evaluated the cytotoxicity of high-osmolar contrast media (HOCM; diatrizoate) and low-osmolar contrast media (LOCM; iohexol) on human renal tubular epithelial cells (HKCs), and determined the regulatory roles of Bax/Bcl-2 and caspase-3 on apoptosis induced by contrast media (CM) in HKCs. METHODS: An HKC line was used. Experiments were divided into 7 groups: the HOCM group with iodine 111 mg/mL, HOCM group with iodine 74 mg/mL, LOCM group with iodine 111 mg/mL, LOCM group with iodine 74 mg/mL, mannitol high-osmolar control group, mannitol low-osmolar control group and a culture media control group . The cytotoxicity of HOCM and LOCM were evaluated by cell proliferation and viability assay (MTT assay) and lactate dehydrogenase (LDH) release. Apoptosis were assessed by Hochest 33258 fluorescence-stained cytospins, TUNEL staining, DNA agarose gel electrophoresis, electron microscope and flow cytometric DNA analysis. The protein ex-pression of Bax/Bcl-2 was determined by Western blot analysis, and caspase-3 activity was also determined by the fluo-rometric method. RESULTS: Compared with the control group, LDH levels increased significantly (p<0.05) and cell viability decreased in cells treated with HOCM or LOCM (p<0.05) in an osmotic pressure-, iodinated ion- and time-dependent manner; in the HOCM groups, diatrizoate induced cultured HKC apoptosis. In the LOCM groups, iohexol did not induce apoptosis. Compared with equal osmotic pressure mannitol, apoptosis increased in HKCs incubated with diatrizoate (p<0.05). Bax/Bcl-2 production and caspase-3 activity were up-regulated in cultured HKCs treated with HOCM iodine 74 or 111 mg/mL meglumine diatrizoate. CONCLUSIONS: Both HOCM and LOCM had toxic effects on HKCs, HOCM was more cytotoxic than LOCM; HOCM induced cultured HKC apoptosis while LOCM did not induce cultured HKC apoptosis in the indicated concentrations. The regulation of apoptosis induced by HOCM in HKCs may be regulated by Bax/Bcl-2 and caspase-3.

Apoptosis↗