3D shape measurement based on structured light field imaging.

In this paper, a three-dimensional (3D) shape measurement method based on structured light field imaging is proposed, which contributes to the biomedical imaging. Generally, light field imaging is challenging to accomplish the 3D shape measurement accurately, as the slope estimation method based on radiance consistency is inaccurate. Taking into consideration the special modulation of structured light field, we utilize the phase information to substitute the phase consistency for the radiance consistency in epi-polar image (EPI) at first. Therefore, the 3D coordinates are derived after light field calibration, but the results are coarse due to slope estimation error and need to be corrected. Furthermore, the 3D coordinates refinement is performed based on relationship between the structured light field image and DMD image of the projector, which allows to improve the performance of the 3D shape measurement. The necessary light field camera calibration is described to generalize its application. Subsequently, the effectiveness of the proposed method is demonstrated with a sculpture and compared to the results of a conventional PMP system.

A two-step DNA barcoding approach for delimiting moth species: moths of Dongling Mountain (Beijing, China) as a case study.

DNA barcoding, based on a fragment of cytochrome c oxidase I (COI) mtDNA, is as an effective molecular tool for identification, discovery, and biodiversity assessment for most animals. However, multiple gene markers coupled with more sophisticated analytical approaches may be necessary to clarify species boundaries in cases of cryptic diversity or morphological plasticity. Using 339 moths collected from mountains surrounding Beijing, China, we tested a pipeline consisting of two steps: (1) rapid morphospecies sorting and screening of the investigated fauna with standard COI barcoding approaches; (2) additional analyses with multiple molecular markers for those specimens whose morphospecies and COI barcode grouping were incongruent. In step 1, 124 morphospecies were delimited into 116 barcode units, with 90% of the conflicts being associated with specimens identified to the genus Hypena. In step 2, 55 individuals representing all 12 Hypena morphospecies were analysed using COI, COII, 28S, EF-1a, Wgl sequences or their combinations with the BPP (Bayesian Phylogenetics and Phylogeography) multigene species delimitation method. The multigene analyses supported the delimitation of 5 species, consistent with the COI analysis. We conclude that a two-step barcoding analysis pipeline is able to rapidly characterize insect biodiversity and help to elucidate species boundaries for taxonomic complexes without jeopardizing overall project efficiency by substantially increasing analytical costs.

Roles of ezrin in the growth and invasiveness of esophageal squamous carcinoma cells.

Ezrin, which crosslinks the cytoskeleton and plasma membrane, is involved in the growth and metastatic potential of cancer cells. Ezrin expression in esophageal squamous cell carcinoma (ESCC) was described recently, but its roles and the underlying mechanism(s) remain unclear. In our study, we first showed that ezrin in ESCC cell is expressed in the nucleus as well as in the cytoplasm and plasma membrane. Then, by using RNAi, we revealed that interference of ezrin expression suppressed the growth, adhesion and invasiveness of ESCC cells. Tumorigenesis experiments revealed that ezrin may directly regulate tumor formation in vivo. To explore the molecular mechanisms through which ezrin contributes to the proliferation and invasiveness of ESCC cells, we used cDNA microarrays to analyze ezrin knockdown cells and the control cells; of 39,000 genes examined, 297 were differentially expressed upon ezrin knockdown, including some proliferation- and invasiveness-related genes such as ATF3, CTGF and CYR61. Furthermore, pathway analysis showed that ezrin knockdown led to decreased activation of the TGF-beta and MAPK pathways, and ezrin-mediated cell invasiveness alteration was dependent on the activation of these pathways. Finally, immunohistochemical staining on 80 ESCC specimens and 50 normal esophageal mucosae revealed that the expression levels of 3 altered genes involved in the regulation of cell proliferation and tumor metastasis, including CTGF, CYR61 and ATF3, were altered in ESCCs, and their expression pattern correlated with ezrin expression. Taken together, we propose that ezrin might function in the growth and invasiveness of ESCC cells through the MAPK and TGF-beta pathways.

A novel alternative spliced variant of neutrophil gelatinase-associated lipocalin receptor in oesophageal carcinoma cells.

Recent studies suggest that NGAL (neutrophil gelatinase-associated lipocalin) is a novel iron transporter with functions distinct from that of transferrin and mediates a new iron-delivery pathway. To get a better understanding of NGAL function in oesophageal carcinoma, we analysed the expression of NGAL receptors in oesophageal carcinoma cells and identified a novel spliced variant designated NgalR-3. When expressed in a heterologous system, the protein produced from this novel spliced variant exhibits the biochemical characteristics of interaction and co-localization with NGAL protein in vivo. This new finding suggests that NgalR-3 may act as a potential NGAL receptor and play a role in NGAL-mediated iron transport in oesophageal carcinoma.

[The promotive effects of N-nitrosopiperidine on the malignant transformation of the immortalized esophageal epithelium induced by human papillomavirus].

BACKGROUND: Study on the promotive effects of N-nitrosopiperidine on carcinogenesis process was performed, based on the immortalization of human fetal esophageal epithelium induced by human papillomavirus (HPV) 18E6E7 genes. METHODS: The immortalized esophageal epithelium SHEE was induced by HPV18E6E7. The cells at 17th passages were cultured in 50 ml flasks. The N-nitrosopiperidine (NPIP) 0, 2, 4, 8 mmol/L added to the cultured medium of SHEE cells for 3 weeks. The morphology, proliferation and apoptosis of the cells were studied by phase contrast microscopy and flow cytometry. Modal number of chromosomes was analyzed by standard method. Tumorigenicity of the cells was assessed by soft agar colony formation and by transplantation of cells into nude mice. Expression of HPV was detected by Western blot. RESULTS: When cells were exposed to high concentration (8 mmol/L) of NPIP, cell death was increased, leaving a few live cells. In normal cultural medium instead of NPIP proliferative status of the cells restored after 4 weeks and the cells progressed to the proliferation stage with continuous replication and atypical hyperplasia. At the end of the 8th week, the cells appeared with large colonies in soft-agar and tumor formation in transplanted nude mice. When the cells were cultured in 2, 4 mmol/L NPIP the doubling passage was delayed and without tumor formation in transplanted nude mice. Modal number of chromosomes was 61-65, in 8 mmol/L NPIP group and control group, 56-61. Expression of HPV18 appeared in experimental and control groups. CONCLUSION: NPIP promotes malignant change of the immortalized esophageal epithelial cells induced by HPV18E6E7. HPV18E6E7 synergy with NPIP will accelerate malignant transformation in esophageal epithelium.

Expression, purification and characterization of the Hepatitis B virus entire envelope large protein in Pichia pastoris.

The current HBsAg vaccine has performed a vital role in preventing the transmission of HBV during the past 20 years. However, a number of individuals still show no response or a low response to the vaccine. In the present study, the HBV envelope large protein gene was cloned into the eukaryotic expression vector pPIC9k and was subsequently expressed in the yeast Pichia pastoris. The HBV large protein (L protein) was produced and secreted into the medium, where some of the L protein formed particles. The soluble L protein and particles were purified by column chromatography and sucrose density gradient centrifugation. Western blot analysis demonstrated that the particle was composed of both HBV L and S protein. To compare the antigenicity of the L protein and HBsAg, rabbits were immunized with the soluble L protein and the commercially available HBV vaccine and the increasing level of antibodies was determined by ELISA. The results showed that the anti-HBsAg antibody, from rabbits injected with the L protein at a dose of 2 and 10microg, was detected on day 14, whereas rabbits vaccinated with 10 and 2microg HBsAg did not develop antibodies until day 21 and 28, respectively. The antibody level in groups inoculated with the L protein was approximately 50% higher than in the group injected with HBsAg using the same dose. Furthermore, 2microg L protein induced a significant and rapid anti-HBsAg antibody response than 10microg HBsAg. Therefore, we suggest that the L protein is an ideal candidate for a new generation HB vaccine to protect people from HBV infection.

Purification and application of bacterially expressed chimeric protein E1E2 of hepatitis C virus.

E1 and E2 glycoproteins are structural components of hepatitis C virus (HCV) virion. They are involved in cellular receptors interaction, neutralising antibodies elicitation, and viral morphogenesis. They are considered as major candidates for anti-HCV vaccine. In this report, we first expressed tandem E1E2 as well as C-terminally truncated E1 fragment and C-terminally truncated E2 fragment, respectively, in Escherichia coli cells and the proteins were purified to homogenesis. All the purified proteins can react specifically with patient sera. Both purified chimeric protein E1E2 and protein E2 can interact with a putative cellular receptor CD81, while purified protein E1 cannot interact with CD81. The sera of rabbit immunized with the E1E2 inhibited the binding of E2 protein to the major extracellular loop of human CD81 and reacted with both proteins E1 and E2, respectively. Anti-E1 and E2 antibodies can be generated simultaneously in the rabbit immunized with the E1E2, and the titers of antibodies were 63 or 56% higher than the titers induced by E1 or E2 alone, respectively. The results suggest that E1 and E2 can enhance their immunogenicity each other in chimeric protein E1E2 and the E. coli-derived chimeric protein E1E2 and corresponding antisera can be used as an useful tools in anti-HCV vaccine research.

[Differential expression of STRBP8, a new candidate oncogene, in cancerization of human immortalized esophageal epithelial cells].

BACKGROUND & OBJECTIVE: Recently, changes in composition, structure, and function of nuclear matrix proteins (NMPs) in generation and development of tumors evoked more and more attention. Separation and identification of tumor-related NMPs is a new way to search for tumor specific biomarkers, and to study tumor pathogenesis. This study was to analyze differential expression of STRBP8, one of esophageal carcinoma specific NMPs, in cancerization of immortalized human esophageal epithelial cells. METHODS: NMPs were extracted from immortalized human esophageal epithelial cell line SHEE and malignantly transformed esophageal carcinoma cell line SHEEC. Differential expression of STRBP8 was detected by two-dimensional electrophoresis (2-DE), matrix-assisted laser desorption/ionization time of flying mass spectrometry (MALDI-TOF-MS), and reverse transcription-polymerase chain reaction (RT-PCR). STRBP8 cDNA obtained by RT-PCR was linked to pGEM-T easy vector, and introduced into TOP10F' E.coli competent cells. Positive clones were sequenced and analyzed with BLAST. RESULTS: STRBP8 was only detected in SHEEC cells by 2-DE, MALDI-TOF-MS, and RT-PCR. The sequence of positive clones contained STRBP8 cDNA was identical to that in GenBank database. CONCLUSION: STRBP8, as a candidate oncogene, might relate to cancerization of esophageal epithelial cells, which might be a specific biomarker of esophageal carcinoma, and probe into the pathogenesis of esophageal carcinoma.

[Expression of fascin 1 gene in the process of the immortalized esophageal carcinoma carcinogenesis].

BACKGROUND & OBJECTIVE: Fascin 1 is the 55kDa F-actin- binding cytoskeleton protein. Fascin 1 gene was cloned from a human teratocarcinoma. Up to now, the carcinogenesis mechanism of esophageal squamous cell carcinoma is unclear. The study was designed to identify the differentially expressed proteins and mRNAs between the human immortalized esophageal epithelial cell line (SHEE) transfected by human papillomavirus type 18 E6E7 and the malignant transformation cell line (SHEEmt), which is derivated from SHEE, and to further understand the carcinogenesis mechanisms of esophageal squamous cell carcinoma. METHODS: Cellular proteins were separated by two-dimensional electrophoresis and differentially expressed proteins were identified by matrix-assisted laser desorption/ionization time of flying mass spectrometry (MALDI-TOF-MS). The mRNA of fascin 1 gene was assayed by reverse transcription polymerase chain reaction (RT-PCR) and its product was analyzed by sequencing assay. RESULTS: The results manifested 9 genes expressed differently in the progress of malignant transformation of SHEE to SHEEmt, fascin 1 protein increased about 3.64 times and its mRNA increased about 16.17 times. CONCLUSION: The upregulated expression of fascin 1 gene may be correlated with the malignant transformation of SHEE to SHEEmt.

The multistage process of carcinogenesis in human esophageal epithelial cells induced by human papillomavirus.

To investigate the multistage process of carcinogenesis, the progressive alteration of the morphology, telomerase, cytogenesis, oncogenes and tumorigenicity in the process of immortalization and malignant transformation of the human fetal esophageal epithelial cell (SHEE) was studied. The SHEE cells were immortalized by gene E6E7 of human papilloma virus (HPV) type 18 in our laboratory and continually cultivated over 100 passages, which had been malignantly transformed. Cells at the 11th, 35th, 65th and 100th passage were examined according to the following criteria: morphological changes of cell growth, contact-inhibition and anchorage-independent growth (AIG); the cell proliferative and apoptotic index; the modal number of chromosomes; c-myc, p53, bcl-2, ras; telomere length and activities of telomerase and tumorigenicity in nude mice or severe combined immunodeficient (SCID) mice. The cells of the 11th passage were well differentiated and the cells of 100th passage were relatively poorly differentiated with polymorphism, while the cells of 35th and 65th had two distinct differentiations. The proliferative indexes were 21.1%, 32.5%, 33.2%, and 40.9% and the apoptotic indexes were 3.3%, 2.7%, 3.5%, 2.7% in the 11th, 35th, 65th and 100th passage respectively. Karyotypes of four cell passages belonged to hyperdiploidy and hypotriploidy. C-myc, ras, p53 genes were low in the 10th and 35th, and high in the 65th and 100th passage, but bcl-2 was low in 4 passages. Telomere length sharply decreased from normal fetal esophagus cells until the 35th passage, but it was stably expressed in the 65th and 100th passage. The activities of telomerase were expressed in cells of the 35th, 65th and 100th passages. The efficiency of AIG varied in different passages of the SHEE cell and was absent in the 11th passage, low efficiency in the 35th passage and 65th passage, and high efficiency in the 100th passage. Transplanted cells of the 65th and 100th passage into SCID mice resulted in tumor formation, but only the 100th passage cells could grow in nude mice. All of these characteristic changes were in dynamic progressive process. These data demonstrate that carcinogenesis of esophageal epithelial cells induced by HPV is the multistage process, which goes through the initial, immortal, premalignant and malignant transformation stages. The generation of esophageal carcinoma is caused by the accumulation of cellular, genetic and molecular changes.

Separation and identification of differentially expressed nuclear matrix proteins between human esophageal immortalized and carcinomatous cell lines.

AIM: To separate and identify differentially expressed nuclear matrix proteins (NMPs) between the immortalized human esophageal epithelial cell line (SHEE) and the malignantly transformed esophageal carcinoma cell line (SHEEC), and to provide new ways for finding specific markers and the pathogenesis of esophageal carcinoma. METHODS: SHEE and SHEEC cell lines were used to extract NMPs. The quality of NMPs was monitored by Western blot analysis including DNA topoisomerase IIalpha, proliferation cell nuclear antigen (PCNA) and histone. NMPs of SHEE and SHEEC were analyzed by two-dimensional electrophoresis (2-DE), silver staining and PDQuest6.2 image analysis software. Three spots in which the differentially expressed NMPs were more obvious, were selected and analyzed with matrix-assisted laser desorption/ionization time of flying mass spectrometry (MALDI- TOF-MS) and database search. RESULTS: Western blot analysis revealed that DNA topoisomerase IIalpha and PCNA were detected, and the majority of histones were deleted in NMPs of SHEE and SHEEC. After 2-DE image analysis by PDQuest6.2 software, the 2-DE maps were detected with an average of 106+/-7.1 spots in SHEE and 132+/-5.0 spots in SHEEC. Most of them were matched one another (r=0.72), only 16 protein spots were found differing in intensity. Three NMPs including cytoskeletal tropomyosin, FK506-binding protein 6, similar to retinoblastoma binding protein 8 were preliminarily identified by MALDI- TOF-MS. CONCLUSION: These differentially expressed NMPs may play an important role during malignant transformation from SHEE to SHEEC. Their separation and identification will contribute to searching for specific markers and probing into the pathogenesis of esophageal carcinoma.

E6/E7 genes of human papilloma virus type 18 induced immortalization of human fetal esophageal epithelium.

To study the role played by human papilloma virus (HPV) in carcinogenesis, immortalized esophageal epithelial cells were induced by E6 and E7 genes of HPV type 18 and the biological behavior was studied. Human fetal esophageal epithelial cells were transfected with recombined HPV18E6E7AAV and were cultured and passaged in medium M199. In both the 10th passage (SHEE10) and the 31st passage (SHEE31), their proliferative rates by flow cytometry and their abilities to grow and form colonies in soft agar, or to form tumors in SCID mice were examined. The HPV18 genes of E6E7 and its expression were determined using PCR methods. Cellular telomerase activity was detected by TRAP and chromosomes were analyzed by standard method. Immortalized cell lines of esophageal epithelium induced by the HPV18E6E7 were successfully established and cultured for >100 passages over 4 years. The result of PCR showed that the E6E7 gene of HPV18 was detectable in both cell clones. Both of them were unable to grow in soft-agarose medium and failed to produce tumors in SCID mice. Flow cytometry demonstrated an average of 43% proliferation index in SHEE31, but 28% in SHEE10. Telomerase activity was clearly identified in SHEE31 but not in SHEE10. Cytogenetic analysis demonstrated progression of chromosomal abnormalities with increasing trisome. Our data indicated that genes E6/E7 of the HPV18 were capable of inducing immortalization in fetal esophageal epithelial cells. The immortal phenotype requires both activation of telomerase and genetic alterations that abrogate normal differentiation and promote cellular proliferation. This cell line can assist us to characterize the role played by HPV in carcinogenesis.

Cytogenetic and molecular genetic changes in malignant transformation of immortalized esophageal epithelial cells.

The purpose of this study was to evaluate the extent to which the expression of p53, c-myc, bcl-2, ras genes and chromosomes, along with activity of hTERT, impacts on the malignant transformation of immortalized esophageal epithelial cells. The SHEE cell line was established from an embryonic esophageal epithelial cell induced by transduction of E6E7 genes of human papillomavirus type 18 (HPV18E6E7). In cells of the 85th passage (SHEE85), the malignant transformation of SHEE was confirmed by morphology, cell proliferative index and tumor formation in SCID mice. C-myc, p53, bcl-2 and ras genes were assayed by the multi-PCR method with house-keeping gene GAPDH as control. The modal number of chromosomes was analyzed and its expression of subunit of telomerase, hTERT, was assessed by RT-PCR. Expression of HPV18E6E7 was assayed by Western blotting. The results showed that cells of SHEE85 were atypical and exhibited proliferative status with a proliferation index of 45.70%. Tumors formed in SCID mice with invasion of adjacent tissue. The karyotype belonged to hypotriploid and displayed expression of hTERT. C-myc, k-ras, bcl-2 and p53 (expression of phosphoprotein) were positive in SHEE85. Expression of HPV18E6E7 was positive. Taken together, SHEE85 cells were in fully malignant transformation and their molecular mechanism involved the expression of cellular genes, such as p53, bcl-2, c-myc and ras, and aberrance of chromosomes. It is probable that all of these changes were related with HPV18E6E7.

[Functions of neutrophil gelatinase-associated lipocalin in the esophageal carcinoma cell line SHEEC].

Neutrophil gelatinase-associated lipocalin (NGAL) is a novel member of the lipocalin family and may be a new human oncogene product, but function of NGAL is not clear in the cancer. It was recently found that NGAL was overexpressed in the progression of malignant transformation from human immortalized esophageal epithelial cell line SHEE to esophageal carcinoma cell line SHEEC. This indicated that cell line SHEEC was a good model for exploring functions of NGAL in the carcinogenesis. The effects of blocking transcription of NGAL gene on invasion, division and proliferation of SHEEC cells were studied by antisense blocking RNA technique and tumor formation in nude mice. The results showed that the antisense blocking of transcription of NGAL gene not only decreased effectively the activity of MMP-9 and MMP-2 secreted by SHEEC cells, but suppressed significantly also the invasion of these cells in nude mice. However, the telomere length, the content of the cellular topoisomerase II-alpha and cellular proliferation index (PI) of the SHEEC cells have not been changed markedly. These results indicate that NGAL is possibly involved in invasion of tumor cells by regulating activity of MMP-9 and MMP-2, but is not apparently related with division and proliferation of tumor cells in SHEEC.

[Cloning and identification of 5'-untranslated region (UTR) and 3'-untranslated region of neutrophil gelatinase-associated lipocalin (NGAL) gene from esophageal carcinoma cell line SHEEC].

BACKGROUND & OBJECTIVE: Neutrophil gelatinase-associated lipocalin (NGAL) was a novel member of the lipocalin family. The authors previously found that NGAL was overexpressed in the progress of malignant transformation from human immortalized esophageal epithelial cell line SHEE to esophageal carcinoma cell line SHEEC. However, the regulation mechanism of NGAL overexpression was not known. The objective of this study was to clone 5'-untranslated region(5'-UTR) and 3'untranslated region (3'-UTR) of NGAL in SHEEC and to analyze their structural characters. METHODS: 5'-UTR and 3'-UTR of NGAL were cloned from SHEEC using rapid amplification of cDNA ends(RACE). After sequencing the alignment of their nucleotides was analyzed by BLAST database of NCBI and the potential cis-acting elements in the 3'-UTR were identified by computer analysis. RESULTS: The authors cloned and sequenced 69 bp 5'-UTR and 147 bp 3'-UTR of NGAL gene on the basis of the previous works and did not find any base pair mutation. CONCLUSION: NGAL gene from SHEEC had the entire 5'-UTR and 3'-UTR.

Progressive transformation of immortalized esophageal epithelial cells.

AIM: To investigate the progressive transformation of immortal cells of human fetal esophageal epithelium induced by human papillomavirus, and to examine biological criteria of sequential passage of cells, including cellular phenotype, proliferative rate, telomerase, chromosome and tumorigenicity. METHODS: The SHEE cell series consisted of immortalized embryonic esophageal epithelium which was in malignant transformation when cultivated over sixty passages without co-carcinogens. Cells of the 10th, 31st, 60th and 85th passages were present in progressive development after being transfected with HPV. Cells were cultivated in a culture flask and 24-hole cultural plates. Progressive changes of morphology, cell growth, contact-inhibition, and anchorage-dependent growth characteristics were examined by phase contrast microscopy. The cell proliferation rate was assayed by flow cytometry. The modal number of chromosomes was analyzed. HPV18E(6)E(7) was detected by Western blot methods and activities of telomerase were analyzed by TRAP. Tumorigenicity of cells was detected with soft agar plates cultivated and with tumor formation in SCID mice. RESULTS: In morphological examination the 10th passage cells were in good differentiation, the 60th and 85th passages cells were in relatively poor differentiation, and the 31st passage cells had two distinct differentiations. The characteristics of the 85th and 60th passage cells were weakened at contact-inhibition and anchorage-dependent growth. Karyotypes of four stages of cells belonged to hyperdiploid or hypotriploid, and bimodal distribution of chromosomes appeared in the 31st and 60th passage cells. All of these characteristics combined with a increasing trend. The activities of telomerase were expressed in the latter three passages. Four fourths of SCID mice in the 85th passage cells and one fourth of SCID mice in the 60th passage cells developed tumors, but the cells in the 10th and 31st passage displayed no tumor formation. CONCLUSION: In continual cultivation of fetal esophageal epithelial cells with transduction of HPV18E(6)E(7), cells from the 10th to the 85th passage were changed gradually from preimmortal, immortal, precancerous to malignantly transformed stages. All of these changes were in a dynamic progressive process. The establishment of a continuous line of esophageal epithelium may provide a in vitro model of carcinogenesis induced by HPV.

Immortal phenotype of the esophageal epithelial cells in the process of immortalization.

To search for potential biomarkers used to monitor the process of immortalization, we investigated the relative level of telomerase activity and other immortal phenotypes in the SHEE esophageal epithelial cell line. This human fetal esophageal epithelial cell line, induced by human papilloma virus (HPV) 18 E6E7, was continually propagated over 100 passages. Fourteenth passage cells (SHEE14) were cultured in a flask with a serum-free medium and continually cultured to the 30th passage (SHEE30). Cells of SHEE14, SHEE20 and SHEE30 were examined according to cell morphology, cell cycle, apoptosis, contact-inhibition growth, anchorage- dependency, dose-dependency to epithelial growth factors (EGF), telomerase activity and tumorigenicity. The SHEE14 cells exhibited good differentiation with contact-inhibition and anchorage-dependent growth. The SHEE20 cells exhibited increase of senescent and apoptotic cells, and difficulty in propagation. The SHEE30 cells exhibited a higher proliferative index and some undifferentiated cells, with weakened contact-inhibition and anchorage-dependent growth. The telomerase was activated in cells of SHEE30, but not in SHEE14 and SHEE20 cells. The different response to dose-dependency to EGF was not statistically different in SHEE14 and SHEE30. Three groups of cells displayed lack of tumor formation in nude mice. Compared with SHEE14 and SHEE20, SHEE30 cells were of immortalized status with immortal phenotype, which consisted of telomerase activity, increase of cell proliferation, weakened contact-inhibition and anchorage-dependent growth, dose dependency to EGF and lack of tumor formation. From passage 14 to 30th passage, SHEE cells went through cellular senescence, apoptosis and immortalization. With a view toward diagnostic and biological aspects, telomerase activity is a crucial step and a cardinal requirement for immortalization. The telomerase activity and other immortal phenotypes are potential markers for monitoring the process of immortalization.

Identification of differentially expressed proteins between human esophageal immortalized and carcinomatous cell lines by two-dimensional electrophoresis and MALDI-TOF-mass spectrometry.

AIM: To identify the differentially expressed proteins between the human immortalized esophageal epithelial cell line (SHEE) and the malignant transformed esophageal carcinoma cell line (SHEEC), and to explore new ways for studying esophageal carcinoma associated genes. METHODS: SHEE and SHEEC cell lines were used to separate differentially expressed proteins by two-dimensional electrophoresis. The silver-stained 2-D gels was scanned with EDAS290 digital camera system and analyzed with the PDQuest 6.2 Software. Six spots in which the differentially expressed protein was more obvious were selected and analyzed with matrix-assisted laser desorption/ionization time of flying mass spectrometry (MALDI-TOF-MS). RESULTS: There were 107+/-4.58 and 115+/-9.91 protein spots observed in SHEE and SHEEC respectively, and the majority of these spots between the two cell lines matched each other (r=0.772), only a few were expressed differentially. After analyzed by MALDI-TOF-MS and database search for the six differentially expressed proteins, One new protein as well as other five sequence-known proteins including RNPEP-like protein, human rRNA gene upstream sequence binding transcription factor, uracil DNA glycosylase, Annexin A2 and p300/CBP-associated factor were preliminarily identified. CONCLUSION: These differentially expressed proteins might play an importance role during malignant transformation of SHEEC from SHEE. The identification of these proteins may serve as a new way for studying esophageal carcinoma associated genes.

Telomere and telomerase in the initial stage of immortalization of esophageal epithelial cell.

AIM: To search for the biomarker of cellular immortalization, the telomere length, telomerase activity and its subunits in cultured epithelial cells of human fetal esophagus in the process of immortalization. METHODS: The transgenic cell line of human fetal esophageal epithelium (SHEE) was established with E(6)E(7) genes of human papillomavirus (HPV) type 18 in our laboratory. Morphological phenotype of cultured SHEE cells from the 6th to 30th passages, was examined by phase contrast microscopy, the telomere length was assayed by Southern blot method, and the activity of telomerase was analyzed by telomeric repeat amplification protocol (TRAP). Expressions of subunits of telomerase, hTR and hTERT, were assessed by RT-PCR. DNA content in cell cycle was detected by flow cytometry. The cell apoptosis was examined by electron microscopy (EM) and TUNEL label. RESULTS: SHEE cells from the 6th to 10th passages showed cellular proliferation with a good differentiation. From the 12th to the 16th passages, many senescent and apoptotic cells appeared, and the telomere length sharply shortened from 23kb to 17kb without expression of hTERT and telomerase activity. At the 20th passage, SHEE cells overcame the senescence and apoptosis and restored their proliferative activity with expression of telomerase and hTERT at low levels, but the telomere length shortened continuously to the lowest of 3kb. After the 30th passage cells proliferation was restored by increment of cells at S and G2M phase in the cell cycle and telomerase activity expressed at high levels and with maintenance of telomere length. CONCLUSION: At the early stage of SHEE cells, telomeres are shortened without expression of telomerase and hTERT causing cellular senescence and cell death. From the 20th to the 30th passages, the activation of telomerase and maintenance of telomere length show a progressive process for immortalization of esophageal epithelial cells. The expression of telomerase may constitute a biomarker for detection of immortalization of cells.