Abstract 6124: Interleukin-1β and exosomal M6PR secreted by serglycin-overexpressing esophageal cancer cells instigate fibroblasts and endothelial cells to promote esophageal cancer progression

Non-tumor cells can be recruited and educated by cancer cells to facilitate cancer progression. Previously, we found that serum serglycin (SRGN), a secretory proteoglycan, was an independent prognostic marker for patients with esophageal squamous cell carcinoma (ESCC), and that the autocrine pro-invasive effect of SRGN on ESCC cells was mediated by midkine (MDK). Here, we investigated the effects of cancer cell-derived SRGN on human esophageal fibroblasts (HEF) and human umbilical vein endothelial cells (HUVECs). We found that conditioned medium from SRGN-overexpressing ESCC cells (SRGN-CM) promoted the migration and proliferation of HEF. After SRGN-CM treatment, HEF showed increased expression of fibroblast activation protein alpha (FAP), hepatocyte growth factor (HGF) and amphiregulin, and could enhance tumor growth in vivo. In addition, exosomes derived from SRGN-overexpressing ESCC cells (SRGN-Exo) enhanced the tube formation ability of HUVECs. We found that the effects of SRGN-CM on activation, migration and proliferation of HEF were mediated by MDK. To elucidate the mechanisms by which SRGN upregulates HGF and amphiregulin, and promotes endothelial tube formation, cytokine array and mass spectrometry were performed to analyze differentially expressed proteins in SRGN-CM and SRGN-Exo respectively. The results showed upregulated secretion of interleukin (IL)-1β, IL-18 and tumor necrosis factor-α in SRGN-CM, as well as enriched cation-dependent mannose-6-phosphate receptor (M6PR), integrin alpha-5, teneurin-2 and neurogenic locus notch homolog protein 2 in SRGN-Exo, which were validated by Western blot. These effects were dependent on the glycosaminoglycan chains on SRGN. Our data also showed that the enhanced secretion of IL-1β promoted the expression of HGF in HEF by activating extracellular signal-regulated kinase/activating protein-1. Treatment with SU11274, a c-Met (the receptor of HGF) inhibitor, attenuated the proliferation of ESCC cells co-cultured with HEF, which further indicates that IL-1β-induced HGF from HEF plays a significant role in the tumor microenvironment. In addition, the upregulated exosomal M6PR was found to mediate the enhancing effect of SRGN-Exo on endothelial tube formation ability. Notably, the expression level of M6PR in serum samples of patients with ESCC was positively correlated with that of SRGN and with poor survival. Taken together, SRGN overexpression in ESCC cells created a tumor-promoting microenvironment by altering the ESCC cell secretome including exosomes to exert influence on HEF and HUVECs. [This study was supported by Research Grants Council of the Hong Kong SAR, China, GRF Project No. 17100819]

Citation Format: Dongdong Yan, Di Cui, Yun Zhu, Cecilia Ka Wing Chan, Chung Hang Jonathan Choi, Tengfei Liu, Sai Wah Tsao, Stephanie Ma, Annie Lai-Man Cheung. Interleukin-1β and exosomal M6PR secreted by serglycin-overexpressing esophageal cancer cells instigate fibroblasts and endothelial cells to promote esophageal cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6124.

mTORC2-mediated PDHE1α nuclear translocation links EBV-LMP1 reprogrammed glucose metabolism to cancer metastasis in nasopharyngeal carcinoma

EBV infection of preinvasive nasopharyngeal epithelium is believed to be an initiation step during pathogenesis of nasopharyngeal carcinoma (NPC), but the mechanisms remain poorly understood. Here we report a novel mechanism driving NPC metastasis through the EBV-encoded LMP1-mediated metabolic reprogramming, via activation of IGF1-mTORC2 signaling and nuclear acetylation of the Snail promoter by the PDHE1α, an enzyme involved in glucose metabolism. Mechanistically, EBV-LMP1 increases the cellular secretion of IGF1 which promotes phosphorylation of IGF1R to activate mTORC2/AKT signaling linking glucose metabolism to cell motility. LMP1 expression facilitates translocation of mitochondrial PDHE1α into the nucleus in a phosphorylation-dependent manner at Ser²⁹³ residue. Functionally, nuclear PDHE1α promotes H3K9 acetylation on the Snail promoter to enhance cell motility, thereby driving cancer metastasis. Importantly, the IGF1/mTORC2/PDHE1α/Snail axis correlates significantly with disease progression and poor prognosis in NPC patients. This study highlights the functional importance of IGF1-mTORC2-PDHE1α signaling mediated by EBV-LMP1 in NPC pathogenesis.

Establishment and characterization of new tumor xenografts and cancer cell lines from EBV-positive nasopharyngeal carcinoma

The lack of representative nasopharyngeal carcinoma (NPC) models has seriously hampered research on EBV carcinogenesis and preclinical studies in NPC. Here we report the successful growth of five NPC patient-derived xenografts (PDXs) from fifty-eight attempts of transplantation of NPC specimens into NOD/SCID mice. The take rates for primary and recurrent NPC are 4.9% and 17.6%, respectively. Successful establishment of a new EBV-positive NPC cell line, NPC43, is achieved directly from patient NPC tissues by including Rho-associated coiled-coil containing kinases inhibitor (Y-27632) in culture medium. Spontaneous lytic reactivation of EBV can be observed in NPC43 upon withdrawal of Y-27632. Whole-exome sequencing (WES) reveals a close similarity in mutational profiles of these NPC PDXs with their corresponding patient NPC. Whole-genome sequencing (WGS) further delineates the genomic landscape and sequences of EBV genomes in these newly established NPC models, which supports their potential use in future studies of NPC.

The lack of appropriate models restricts pre-clinical research for nasopharyngeal carcinoma (NPC). Here the authors report the development and characterization of NPC patient-derived xenografts (PDXs), and EBV positive NPC cell line from patient tumor, and suggest their potential use in future NPC research.

MicroRNA-377 suppresses initiation and progression of esophageal cancer by inhibiting CD133 and VEGF

Esophageal cancer is one of the most lethal cancers worldwide with poor survival and limited therapeutic options. The discovery of microRNAs created a new milestone in cancer research. miR-377 is located in chromosome region 14q32, which is frequently deleted in esophageal squamous cell carcinoma (ESCC), but the biological functions, clinical significance and therapeutic implication of miR-377 in ESCC are largely unknown. In this study, we found that miR-377 expression was significantly downregulated in tumor tissue and serum of patients with ESCC. Both tumor tissue and serum miR-377 expression levels were positively correlated with patient survival. Higher serum miR-377 expression was inversely associated with pathologic tumor stage, distant metastasis, residual tumor status and chemoradiotherapy resistance. The roles of miR-377 in suppressing tumor initiation and progression, and the underlying molecular mechanisms were investigated. Results of in vitro and in vivo experiments showed that miR-377 overexpression inhibited the initiation, growth and angiogenesis of ESCC tumors as well as metastatic colonization of ESCC cells, whereas silencing of miR-377 had opposite effects. Mechanistically, miR-377 regulated CD133 and VEGF by directly binding to their 3' untranslated region. Moreover, systemic delivery of formulated miR-377 mimic not only suppressed tumor growth in nude mice but also blocked tumor angiogenesis and metastasis of ESCC cells to the lungs without overt toxicity to mice. Collectively, our study established that miR-377 plays a functional and significant role in suppressing tumor initiation and progression, and may represent a promising non-invasive diagnostic and prognostic biomarker and therapeutic strategy for patients with ESCC.

Enhanced IL-6/IL-6R signaling promotes growth and malignant properties in EBV-infected premalignant and cancerous nasopharyngeal epithelial cells

Nasopharyngeal carcinoma (NPC) is etiologically associated with Epstein-Barr virus (EBV) infection. However, the exact role of EBV in NPC pathogenesis remains elusive. Activation of signal transducer and activator of transcription 3 (STAT3) is common in human cancers including NPC and plays an important role in the pathogenesis and progression of human cancers. Interleukin-6 (IL-6), a major inflammatory cytokine, is a potent activator of STAT3. In this study, we report that EBV-infected immortalized nasopharyngeal epithelial (NPE) cells often acquire an enhanced response to IL-6-induced STAT3 activation to promote their growth and invasive properties. Interestingly, this enhanced IL-6/STAT3 response was mediated by overexpression of IL-6 receptor (IL-6R). Furthermore, IL-6R overexpression enhanced IL-6-induced STAT3 activation in uninfected immortalized NPE cells in vitro, and promoted growth and tumorigenicity of EBV-positive NPC cell line (C666-1) in vivo. Moreover, it is shown for the first time that IL-6R was overexpressed in clinical specimens of NPC. IL-6 expression could also be strongly detected in the stromal cells of NPC and a higher circulating level of IL-6 was found in the sera of advance-staged NPC patients compared to the control subjects. Therefore, IL-6R overexpression, coupled with enhanced IL-6/STAT3 signaling may facilitate the malignant transformation of EBV-infected premalignant NPE cells into cancer cells, and enhance malignant properties of NPC cells.

Abstract 1959: Identification of microRNAs that target Id-1 in esophageal cancer

Inhibitor of DNA binding-1 (Id-1) belongs to a family of helix-loop-helix (HLH) proteins that lack the fundamental domain for DNA binding. Since Id-1 is overexpressed in esophageal squamous cell carcinoma (ESCC), and its expression level is associated with cancer invasion and metastasis, suppression of Id-1 may have therapeutic significance. MicroRNAs (miRNAs), which constitute non-coding small RNAs of around 22-nucleotides and negatively regulate gene expression as post-transcriptional regulator, were reported to be involved in carcinogenesis. However, there is limited information about the miRNAs that regulate Id-1. This project aims to identify miRNAs that can target Id-1 and exert tumor suppressive functions. In this study, several bioinformatics software programs, including TargetScan, RegRNA, MicroRNA and EMBL-EBI, were used to predict miRNAs that can directly bind to the 3’UTR of Id-1 mRNA. The miRNAs which have high scores and are predicted to target Id-1 by at least 3 different target prediction algorithms were chosen as candidates for this study. These miRNA candidates are: miR-29 family (miR-29a, miR-29b and miR-39c), miR-330, miR-300, miR-593, miR-654, miR-338, miR-346, miR-632. Plasmids which can over-express these miRNAs were designed and constructed using BLOCK-iT™ Pol II miR RNAi Expression system (Invitrogen®). Successful over-expression of the miRNAs in ESCC cell lines were verified by qRT-PCR. The transient and stable miRNA over-expressing ESCC cells were harvested and subjected to western blot analysis for Id-1 protein expression level. Direct binding of miRNAs to the 3’UTR of Id-1 was analyzed by 3’UTR luciferase assay. The pGL3-Id-1 3’UTR luciferase reporter vector was constructed by cloning the Id-1 3’ UTR downstream of the firefly luciferase open reading frame and the luciferase activities were measured using the Dual Luciferase Assay System. The cell invasion ability of miRNA over-expressing ESCC cells was analyzed by using BD BioCoat™ Matrigel™ Invasion Chamber. Cell proliferation and colony formation assays were performed to investigate the anti-proliferation effect of these miRNAs. In this study, ten miRNA over-expressing plasmids were constructed and over-expression of several miRNAs was achieved. We found that miR-29c could directly target the 3’UTR of Id-1 and down-regulate Id-1 protein level. miR-29c exerts tumor suppressing effects by reducing the ESCC cell invasion ability. Further study using miR-29c inhibitors in western blot assay, Id-1 3’UTR luciferase assay and cell invasion assay will be conducted. In summary, this study shows that miR-29c can suppress Id-1 and inhibit cell invasion in ESCC cells.

This study is supported by General Research Funds from Research Grants Council of the Hong Kong SAR (Project Nos. HKU762610M and HKU763111M)

Citation Format: L Han, B Li, SW Tsao, ALM Cheung. Identification of microRNAs that target Id-1 in esophageal cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1959. doi:10.1158/1538-7445.AM2013-1959

Abstract 4361: Role of Id1-induced IGF2 in autocrine/endocrine promotion of esophageal cancer tumorigenesis and metastasis

Esophageal cancer is the 7th leading cause of cancer death in Hong Kong. The disease is highly lethal (with a 5-year survival rate of ∼14%) because many cases go undetected until the disease is at an advanced stage. Understanding of the underlying mechanisms and the signaling pathways involved in esophageal tumorigenesis is the key to identify new molecular targets for intervention. Id1 (inhibitor of differentiation or DNA binding), a member of the helix-loop-helix (HLH) proteins, is overexpressed in many types of human cancer. Our previous reports provided the first evidence that Id1 activates the phosphatidylinositol-3-kinase (PI3K)/AKT pathway in esophageal squamous cell carcinoma (ESCC) cells, and that there is a positive correlation between Id1 and phosphorylated (p)-AKT expressions in clinical esophageal cancer specimens. We also demonstrated in experimental animal models that Id1 promotes tumor growth and metastasis through activation of PI3K/AKT. Increasing evidence suggests that growth factors secreted from cancer cells can play an important role in cancer progression by modulating the tumor microenvironment and the host systemic environment via autocrine, paracrine, and endocrine mechanisms. In this study, we found that Id1 induced the expression and secretion of IGF2 (insulin-like growth factor 2) in ESCC cells, and that this induction mediated the activation of PI3K/AKT in an autocrine manner. Knockdown of IGF2 in cancer cells or addition of IGF2 neutralizing antibody abrogated the effects of Id1 on proliferation, survival, and invasion of esophageal cancer cells. The mechanisms by which Id1 upregulates IGF2 were studied, and the results indicated that Id1 could protect IGF2 from ubiquitin-proteasomal degradation in ESCC cells. Immunohistochemical analysis of human esophageal cancer tissue microarray showed elevated IGF2 expression in ESCC, which correlated with increased Id1 and p-AKT expressions. Furthermore, our in vivo experiments showed that IGF2 secreted by Id1-overexpressing ESCC xenograft could instigate the growth of distant ESCC tumors, as well as promote metastasis of circulating ESCC cells. Targeting IGF2 with the use of neutralizing antibody had significant antitumor effects on esophageal cancer xenografts in mice. Our findings therefore support that the Id1-IGF2-PI3K/AKT signaling cascade plays an important role in esophageal cancer, and that Id1-overexpressing primary tumors may affect the host systemic environment and contribute to cancer progression. In conclusion, we have uncovered a novel mechanism in the role of Id1 in tumorigenesis which may have significant implications for the development of targeted therapy for esophageal cancer. [This study is supported by the Research Grants Council of the Hong Kong SAR, China (General Research Fund Project no. HKU 762610M)]

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4361. doi:1538-7445.AM2012-4361

Id-1 induces cell invasiveness in immortalized epithelial cells by regulating cadherin switching and Rho GTPases

Epithelial-mesenchymal transition (EMT), characterized by cadherin switching, contributes to cancer metastasis. Our recent study showed that Id-1 (inhibitor of differentiation-1) promotes metastasis in esophageal cancer cells, but whether the invasive and metastatic dynamics can be induced early in the carcinogenesis process is still unclear. Immortalization is regarded as the initial stage in the malignant transformation of normal cells. In this study, we investigated the role and mechanisms of Id-1 in inducing EMT and cell invasiveness in immortalized esophageal epithelial cells. We found that immortalized epithelial cells expressed higher endogenous levels of Id-1 compared with normal cells. Ectopic Id-1 expression inhibited the differentiation of immortalized esophageal epithelial cells and promoted cadherin switching, which was accompanied by increased adhesiveness to extracellular matrix, cell motility, migratory potential and matrix metalloproteinase-dependent invasiveness. GTPase activity assays showed that over-expression or short-hairpin RNA knockdown of Id-1 led to corresponding changes in Rac1 activity, whereas RhoA activity was significantly decreased with Id-1 depletion. Inhibitors targeting Rac1, RhoA, and Rho kinase suppressed the invasiveness of Id-1-expressing NE2-hTERT cells. Knockdown of N-cadherin in Id-1-over-expressing cells inhibited cell invasiveness and down-regulated RhoA activity. These data suggest that the Id-1-induced invasive potential may be regulated through the N-cadherin-RhoA axis and Rac1 activation.

Impact of G₂ checkpoint defect on centromeric instability

Centromeric instability is characterized by dynamic formation of centromeric breaks, deletions, isochromosomes and translocations, which are commonly observed in cancer. So far, however, the mechanisms of centromeric instability in cancer cells are still poorly understood. In this study, we tested the hypothesis that G(2) checkpoint defect promotes centromeric instability. Our observations from multiple approaches consistently support this hypothesis. We found that overexpression of cyclin B1, one of the pivotal genes driving G(2) to M phase transition, impaired G(2) checkpoint and promoted the formation of centromeric aberrations in telomerase-immortalized cell lines. Conversely, centromeric instability in cancer cells was ameliorated through reinforcement of G(2) checkpoint by cyclin B1 knockdown. Remarkably, treatment with KU55933 for only 2.5 h, which abrogated G(2) checkpoint, was sufficient to produce centromeric aberrations. Moreover, centromeric aberrations constituted the major form of structural abnormalities in G(2) checkpoint-defective ataxia telangiectasia cells. Statistical analysis showed that the frequencies of centromeric aberrations in G(2) checkpoint-defective cells were always significantly overrepresented compared with random assumption. As there are multiple pathways leading to G(2) checkpoint defect, our finding offers a broad explanation for the common occurrence of centromeric aberrations in cancer cells.

Id1 overexpression induces tetraploidization and multiple abnormal mitotic phenotypes by modulating aurora A

The basic helix-loop-helix transcription factor, Id1, was shown to induce tetraploidy in telomerase-immortalized nasopharyngeal epithelial cells in this study. Using both transient and stable Id1-expressing cell models, multiple mitotic aberrations were detected, including centrosome amplification, binucleation, spindle defects, and microtubule perturbation. Many of these abnormal phenotypes have previously been reported in cells overexpressing Aurora A. Further experiments showed that Id1 could stabilize Aurora A, whereas knocking down Aurora A expression in Id1-expressing cells could rescue some of the mitotic defects. The mechanisms by which Aurora A could be modulated by Id1 were explored. DNA amplification of the Aurora A locus was not involved. Id1 could only weakly activate the transcriptional activity of the Aurora A promoter. We found that Id1 overexpression could affect Aurora A degradation, leading to its stabilization. Aurora A is normally degraded from mitosis exit by the APC/C(Cdh1)-mediated proteasomal proteolysis pathway. Our results revealed that Id1 and Cdh1 are binding partners. The association of Id1 and Cdh1 was found to be dependent on the canonical destruction box motif of Id1, the increased binding of which may compete with the interaction between Cdh1 and Aurora A, leading to stabilization of Aurora A in Id1-overexpressing cells.

Microtubule breakage is not a major mechanism for resolving end-to-end chromosome fusions generated by telomere dysfunction during the early process of immortalization

Telomeres, the terminal chromosomal structure crucial for maintaining genomic integrity, shorten with deoxyribonucleic acid replications in most human somatic cells. Chromosomes carrying critically short telomeres tend to form end-to-end fusions, which are subject to breakage during cell division. However, it remains obscure how such telomere-mediated fusions are resolved during the process of immortalization, which is an early and indispensable step toward cancer. It has been hypothesized that the breakage could occur at either the microtubule or chromatid, causing numerical or structural chromosome instability, respectively. In this paper, we show that although the distributions of chromosomal segment losses or gains involved in structural aberrations were significantly correlated with the profiles of critically short telomeres in human epithelial cells undergoing immortalization, no such association was detected for whole-chromosome losses or gains in either metaphase or interphase cells. By distinguishing between homologues, we further showed that the specific homologues with critically short telomeres and frequent end-to-end fusions were not preferentially involved in respective whole-chromosome losses or gains. Our data therefore demonstrate that microtubule breakage is not a major mechanism for resolving chromosomal end-to-end fusions in human cells undergoing immortalization. An important implication of this finding is that microtubule-kinetochore attachment is stronger than the chromosome structure.

Latent membrane protein 1 suppresses RASSF1A expression, disrupts microtubule structures and induces chromosomal aberrations in human epithelial cells

Epstein-Barr virus (EBV) infection is closely associated with nasopharyngeal carcinoma (NPC) and can be detected in early premalignant lesions of nasopharyngeal epithelium. The latent membrane protein 1 (LMP1) is an oncoprotein encoded by the EBV and is believed to play a role in transforming premalignant nasopharyngeal epithelial cells into cancer cells. RASSF1A is a tumor-suppressor gene commonly inactivated in many types of human cancer including NPC. In this study, we report a novel function of LMP1, in down-regulating RASSF1A expression in human epithelial cells. Downregulation of RASSF1A expression by LMP1 is dependent on the activation of intracellular signaling of NF-kappaB involving the C-terminal activating regions (CTARs) of LMP1. LMP1 expression also suppresses the transcriptional activity of the RASSF1A core promoter. RASSF1A stabilizes microtubules and regulates mitotic events. Aberrant mitotic spindles and chromosome aberrations are reported phenotypes in RASSF1A inactivated cells. In this study, we observed that LMP1 expression in human epithelial cells could induce aberrant mitotic spindles, disorganized interphase microtubules and aneuploidy. LMP1 expression could also suppress microtubule dynamics as exemplified by tracking movements of the growing tips of microtubules in live cells by transfecting EGFP-tagged EB1 into cells. The aberrant mitotic spindles and interphase microtubule organization induced by LMP1 could be rescued by transfecting RASSF1A expression plasmid into cells. Downregulation of RASSF1A expression by LMP1 may facilitate its role in transformation of premalignant nasopharyngeal epithelial cells into cancer cells.

Role of MEK/ERK pathway in the MAD2-mediated cisplatin sensitivity in testicular germ cell tumour cells

Testicular germ cell tumour (TGCT) is the most common malignancy in young males. Although most TGCTs are sensitive to cisplatin-based chemotherapy, significant numbers of TGCT patients still relapse and die each year because of the development of resistance to cisplatin. Previously, we first reported that a key regulator of the mitotic checkpoint, mitotic arrest deficient-2 (MAD2), was a mediator of cisplatin sensitivity in human cancer cells. In this study, we investigated whether MAD2 played a role in cellular sensitivity to cisplatin in TGCT cells and the underlying molecular mechanisms responsible. Using 10 TGCT cell lines, we found that increased MAD2 expression was correlated with cellular sensitivity to cisplatin, which was associated with activation of the MEK pathway. Treatment of cells expressing high levels of MAD2 with an MEK inhibitor, U0126, led to cellular protection against cisplatin-induced apoptosis. Inactivation of MAD2 by transfecting a dominant-negative construct in TGCT cells with high levels of MAD2 resulted in the suppression of MEK pathway and resistance to cisplatin-induced cell death. These results support previous suggestion on the involvement of mitotic checkpoint in DNA damage response in human cancer cells and demonstrate a possible molecular mechanism responsible for the MAD2-mediated sensitivity to cisplatin in TGCT cells. Our results also suggest that downregulation of MAD2 may be an indicator for identification of TGCT cancer cells that are potentially resistant to cisplatin-based therapy.

Amplification and overexpression of aurora kinase A (AURKA) in immortalized human ovarian epithelial (HOSE) cells

Immortalization is an early and essential step of human carcinogenesis. Amplification of chromosome 20q has been shown to be a common event in immortalized cells and cancers. We have previously reported that gain and amplification of chromosome 20q is a non-random and common event in immortalized human ovarian surface epithelial (HOSE) cells. The chromosome 20q harbors genes including TGIF2 (20q11.2-q12), AIB1 (20q12), PTPN1 (20q13.1), ZNF217 (20q13.2), and AURKA (20q13.2-q13.3), which were previously reported to be amplified and overexpressed in ovarian cancers. Some of these genes may be involved in immortalization of HOSE cells and represent crucial premalignant changes in ovarian surface epithelium. Investigation of the involvement of these genes was examined in four pairs of pre-crisis (preimmortalized) and post-crisis (immortalized) HOSE cells. Overexpression of AURKA (Aurora kinase A), also known as BTAK and STK15, by both real time-quantitative polymerase chain reaction (RT-QPCR) and Western blotting was detected in all the four immortalized HOSE cells examined while overexpression of AIB1 and ZNF217 was observed in two of four immortalized HOSE cells examined. Overexpression of TGIF2 and PTPN1 was not significant in our immortalized HOSE cell systems. The degree of overexpression of AURKA was shown to be closely associated with the amplification of chromosome 20q in immortalized HOSE cells. Fluorescence in situ hybridization (FISH) with labeled P1 artificial clone (PAC) confirmed the amplification of the chromosomal region (20q13.2-13.3) where AURKA resides. DNA amplification of AURKA was also confirmed using semi-quantitative PCR. Our study showed that amplification and overexpression of AURKA is a common and significant event during immortalization of HOSE cells and may represent an important premalignant change in ovarian carcinogenesis.

Establishment and characterization of a human non-small cell lung cancer cell line

Lung cancer is one of the most common causes of cancer death worldwide. Although many efforts have been made to explore the mechanisms involved in the development of lung cancer, the genetic events involved in the pathogenesis of lung cancer are still unclear. For a better mechanistic scope of study, a well-established cellular model is essential. We report the establishment of a squamous cell carcinoma (SCC) cell line of human lung, SCC-37. Chromosomal abnormalities and global genomic alterations of SCC-37 were studied by spectral karyotyping (SKY) and comparative genomic hybridization (CGH), respectively. Results showed that SCC-37 was a hypodiploid with complex chromosomal rearrangements. Some of the alterations, such as the gain of 1q25-qter in SCC-37, have been correlated to the tumor recurrence of non-small cell lung cancer (NSCLC). Other interesting findings include the amplification of 3q25-qter and 12q13, suggesting the existence of important oncogenes in the amplicons. This cell line may thus provide a useful cellular resource for studying the pathogenesis of SCC of the lung in the future.

Inhibitor of apoptosis proteins and ovarian dysfunction in galactosemic rats

Galactosemia is a genetic disease with deficiency of galactose-1-uridyltransferase, resulting in the accumulation of galactose or galactose-1-phosphate in the blood and tissues. Rats were fed with normal rat chow and with a high-galactose diet for 4 weeks to give control and galactosemic groups, and their ovarian function was studied. The two groups of rats were injected with pregnant mare's serum gonadotrophin (PMSG) and were killed at different time points after human chorionic gonadotrophin (hCG) injection. The number of oocytes ovulated in the controls was significantly higher than in the galactosemic group. Morphometric studies of the ovaries also showed a higher number of corpora lutea in the controls. Western blot analysis of granulosa cells showed that the overall expressions of Fas and FasL were lower in the control group and their expressions of inhibitor of apoptosis proteins (IAPs) were higher than in the galactosemic group, especially at 8 h post hCG injection. TDT-mediated dUTP-biotin nick end-labeling (TUNEL) and immunohistochemical staining of ovarian sections with Ki-67 and IAPs showed more apoptotic granulosa cells in the galactosemic group and the expressions of IAPs in granulosa cells also confirmed the result of the Western blot. These findings support our hypothesis that ovarian dysfunction in galactosemic rats is due to increased apoptosis in granulosa cells of maturing follicles.

The association of E-cadherin expression and the methylation status of the E-cadherin gene in nasopharyngeal carcinoma cells

Loss of E-cadherin (E-cad) has been associated with progression and poor survival in nasopharyngeal carcinoma (NPC). In this study, we investigated the role of methylation on E-cad inactivation in NPC cell lines, as well as in NPC tissue samples. Using 6 NPC cell lines, we found that methylation of the E-cad 5' CpG island promoter region was correlated with the loss of both mRNA and E-cad protein expression in these cell lines. In addition, using 29 NPC and 10 non-malignant nasopharyngeal samples, we also observed 5' CpG methylation of the E-cad gene in 52% (15 out of 29) NPC samples, but in only 10% (1 out of 10) of the non-malignant nasopharyngeal tissues. Our findings indicate that 5' CpG island methylation of the E-cad gene may play an important part in the inactivation of E-cad in NPC. Our results also suggest that reducing the methylation of the E-cad gene may be a potential therapeutic strategy for NPC.

Expression of e-cadherin and beta-catenin in trophoblastic tissue in normal and pathological pregnancies

E-cadherin and beta-catenin are cell-cell adhesion molecules, which are thought to play an important role in trophoblastic differentiation and remodelling during gestation. Their expression may be altered in pathological conditions with trophoblastic invasion. In this study, we used immunohistochemical methods to study the pattern of expression of E-cadherin and beta-catenin in villous trophoblastic tissue in normal and pathological pregnancies. In villous trophoblastic tissue, E-cadherin had a membranous distribution, whereas beta-catenin had a mixed-membranous and granular cytoplasmic distribution. The levels of expression of E-cadherin and beta-catenin correlated with each other. From first to third trimesters, the expression of both E-cadherin and beta-catenin showed a decreasing trend. In preeclampsia, there was an up-regulation of E-cadherin and beta-catenin expression. In placenta accreta, the level of expression of both did not differ from that in normal third-trimester placenta. In gestational trophoblastic diseases, there was a general trend of down-regulation of both E-cadherin and beta-catenin. Altered expression of E-cadherin and beta-catenin may play a role in the development of normal and pathological placentas.

Protection of sperm DNA against oxidative stress in vivo by accessory sex gland secretions in male hamsters

Reactive oxygen species scavengers present in male accessory sex gland secretions might afford antioxidant protection to sperm DNA. This study was conducted to determine whether accessory sex gland secretions protect the genome and function of spermatozoa against oxidative damage in the uterus. Male golden hamsters were divided into four experimental groups: (i) all accessory sex glands removed; (ii) ampullary glands removed; (iii) ventral prostate gland removed and (iv) sham-operated controls. Ejaculated spermatozoa recovered from uteri 15-30 min after mating with experimental males and caput and cauda epididymal spermatozoa obtained from intact males were incubated in 0-20 mmol NADPH l(-1) for 2 h. These spermatozoa and untreated uterine spermatozoa were processed for two types of comet assay (single cell gel electrophoresis): alkaline comet assay (pH > 13) which revealed single-strand DNA breakage and neutral comet assay (pH 9) which revealed double-strand DNA breakage. In comparison with the sham-operated controls, spermatozoa that had not been exposed to accessory sex gland secretions had a higher incidence and more extensive single-strand DNA damage with increasing concentrations of NADPH. Spermatozoa from hamsters without ampullary glands and from hamsters without the ventral prostate glands were similar to those of the control group. After incubation with NADPH, the capacity of spermatozoa from hamsters without accessory glands and from sham-operated controls to fuse with oocytes in vitro was reduced. However, only hamsters without accessory glands showed a negative correlation between single-strand DNA damage and sperm-oocyte fusion. Cauda epididymal spermatozoa were less susceptible to NADPH treatment compared with caput epididymal spermatozoa. The results of the present study showed that male accessory sex gland secretions can preserve the integrity of the sperm genome.