International cancer seminars: a focus on esophageal squamous cell carcinoma

The International Agency for Research on Cancer (IARC) and the US National Cancer Institute (NCI) have initiated a series of cancer-focused seminars [Scelo G, Hofmann JN, Banks RE et al. International cancer seminars: a focus on kidney cancer. Ann Oncol 2016; 27(8): 1382-1385]. In this, the second seminar, IARC and NCI convened a workshop in order to examine the state of the current science on esophageal squamous cell carcinoma etiology, genetics, early detection, treatment, and palliation, was reviewed to identify the most critical open research questions. The results of these discussions were summarized by formulating a series of 'difficult questions', which should inform and prioritize future research efforts.

Sex steroid hormones in relation to Barrett's esophagus: an analysis of the FINBAR Study

Previously, we observed strong positive associations between circulating concentrations of free testosterone and free dihydrotestosterone (DHT) in relation to Barrett's esophagus in a US male military population. To replicate these findings, we conducted a second study of sex steroid hormones and Barrett's esophagus in the Factors Influencing the Barrett/Adenocarcinoma Relationship (FINBAR) Study based in Northern Ireland and Ireland. We used mass spectrometry to quantitate EDTA plasma concentrations of nine sex steroid hormones and ELISA to quantitate sex hormone-binding globulin in 177 male Barrett's esophagus cases and 185 male general population controls within the FINBAR Study. Free testosterone, free DHT, and free estradiol were estimated using standard formulas. Multivariable logistic regression estimated odds ratios (OR) and 95% confidence intervals (95%CI) of associations between exposures and Barrett's esophagus. While plasma hormone and sex hormone-binding globulin concentrations were not associated with all cases of Barrett's esophagus, we did observe positive associations with estrogens in younger men (e.g. estrone + estradiol OR_{continuous per ½IQR}  = 2.92, 95%CI:1.08, 7.89), and free androgens in men with higher waist-to-hip ratios (e.g. free testosterone OR_{continuous per ½IQR}  = 2.71, 95%CI:1.06, 6.92). Stratification by body mass index, antireflux medications, and geographic location did not materially affect the results. This study found evidence for associations between circulating sex steroid hormones and Barrett's esophagus in younger men and men with higher waist-to-hip ratios. Further studies are necessary to elucidate whether sex steroid hormones are consistently associated with esophageal adenocarcinogenesis.

Matrix Metalloproteinase-3 Differences in Oral and Skin Fibroblasts

While skin wounds heal by scarring, wounds of oral mucosa show privileged healing with minimal scar formation. Our hypothesis was that phenotypic differences between oral and skin fibroblasts underlie these differences in healing. The aims of this study were to compare MMP-3 expression by oral and skin fibroblasts and investigate a role for MMP-3 in mediating collagen gel contraction. Oral fibroblasts induced significantly greater gel contraction than did paired skin cells. Inhibition of MMP activity significantly inhibited gel contraction by both cell types. Specific inhibition of MMP-3 activity reduced gel contraction by oral, but not skin, fibroblasts. Oral fibroblasts produced significantly higher levels of MMP-3 than did skin fibroblasts at all levels studied. TGF-β1 and -β3 isoforms stimulated MMP-3 expression at mRNA, protein, and activity levels by both fibroblast populations. Results suggest that increased MMP-3 production by oral fibroblasts may underlie the differences in wound-healing outcome seen in skin and oral mucosa.

Identification of a methylation hotspot in the death receptor Fas/CD95 in bladder cancer

We characterized Fas immunoreactivity, functionality and its role in the response to mitomycin-C (MMC) chemotherapy in vitro in cell lines and in vivo in bladder washings from 23 transitional cell carcinoma of the bladder (TCCB) patients, harvested prior to and during MMC intravesical treatment. Having established the importance of functional Fas, we investigated the methylation and exon 9 mutation as mechanisms of Fas silencing in TCCB. For the first time, we report p53 up-regulation in 9/14 and Fas up-regulation in 7/9 TCCB patients during intravesical MMC treatment. Fas immunoreactivity was strong in the TCCB cell line T24 and in 17/20 (85%) tumor samples from patients with advanced TCCB. T24 and HT1376 cells were resistant to MMC and recombinant Fas ligand, whilst RT4 cells were responsive to Fas ligand and MMC. Using RT4 cells as a model, siRNA targeting p53 significantly reduced MMC-induced p53 and Fas up-regulation and stable DN-FADD transfection decreased MMC-induced apoptosis, suggesting that functional Fas enhances chemotherapy responses in a p53-dependent manner. In HT1376 cells, 5-aza-2-deoxycytidine (12 µM) induced Fas immunoreactivity and reversed methylation at CpG site -548 within the Fas promoter. This site was methylated in 13/24 (54%) TCCB patient samples assessed using Methylation-Specific Polymerase Chain Reaction. There was no methylation at either the p53 enhancer region within the first intron or at the SP-1 binding region in the promoter and no mutation within exon 9 in tumor DNA extracted from 38 patients. Methylation at CpG site -548 is a potential target for demethylating drugs.

Asymptomatic shedding of HSV-1 in patients undergoing oral surgical procedures and attending for noninvasive treatment

Oral surgery and stress can trigger and/or increase asymptomatic shedding of herpes simplex virus type-1 (HSV-1) into human saliva. In this investigation we examined the frequency of HSV-1 shedding in 32 patients undergoing an oral surgery procedure compared with 40 control patients attending for noninvasive treatment. Control patients comprised 18 migraine patients and 22 patients with temporomandibular (TMD) joint problems. Nested-PCR was carried out on oral rinses collected from each patient prior to treatment and 7 days post-treatment. Fifty-two of sixty-one seropositive patients were positive for HSV-1 DNA in one or both oral rinses. The frequencies of HSV-1 shedding for the oral surgery and control patients were 84.6% and 85.7% respectively. Seropositive patients who started shedding after treatment were significantly higher in oral surgery patients (46.2%) compared to control patients (34.3%). Shedding of HSV-1 in the oral cavity is not only increased by direct surgical trauma, but also appears to be common in migraine and TMD patients attending for general dental treatment. Thus pain or pain-induced stress as well as anxiety associated with dental treatment may also be a risk factor for asymptomatic shedding in specific seropositive patients attending for dental treatment.

Regulation of keratinocyte growth factor and scatter factor in cyclosporin-induced gingival overgrowth

BACKGROUND

Epithelial proliferation is a histological characteristic of drug-induced gingival overgrowth. Keratinocyte growth factor (KGF) and scatter factor (SF) are fibroblast-derived growth factors with potent mitogenic and motogenic effects on epithelial cells, and, therefore, could be involved in the pathogenesis of gingival overgrowth. The aims of this study were to investigate: (i) the effects of cyclosporin on KGF and SF expression by gingival fibroblasts; and (ii) the expression levels of KGF and SF mRNA in normal and overgrown gingival tissue.

METHODS

The KGF and SF protein production was determined by enzyme-linked immunosorbent assay. Relative levels of KGF and SF mRNA expression were determined using semi-quantitative reverse transcriptase polymerase chain reaction. Expression levels in biopsies of normal and overgrown gum were also determined.

RESULTS

In overgrown fibroblasts, 500 ng/ml cyclosporin significantly inhibited KGF and SF mRNA and protein while 2000 ng/ml cyclosporin induced a stimulatory effect. In normal cells cyclosporin significantly increased both KGF and SF. KGF and SF mRNA was detected in both normal and overgrown tissues with a tendency towards increased expression levels in overgrown tissue.

CONCLUSION

These results suggest that KGF and SF may have an important role in cyclosporin-induced gingival overgrowth.

Effect of a dCTP:dTTP pool imbalance on DNA replication fidelity in Friend murine erythroleukemia cells

Nucleotide pool imbalances have been reported to affect the fidelity of DNA replication and repair in prokaryotic and eukaryotic cells. We have reported previously that the mutagen-hypersensitive thymidine kinase (TK)-deficient Friend erythroleukemia (FEL) cells (subclones 707BUF and 707BUE), have a more than sixfold increase in the dCTP:dTTP pool ratio when compared to that of wild-type, TK-positive (TK(+)) clone 707 cells. In this study we present the results of an investigation of the effect of the dCTP:dTTP pool imbalance on the accuracy of DNA replication within 707BUF cells. We examined the spontaneous mutation spectra occurring at the adenine phosphoribosyltransferase (aprt) locus within clone 707 (TK(+)) and 707BUF (TK(-)) FEL cells. Mutations recovered at the aprt locus in FEL cells comprised: base substitutions (43:73), frameshifts (14:13.5), and deletions (43:13.5) [clone 707 (TK(+)):707BUF (TK(-)), respectively, expressed as percentages]. A comparison of the mutation spectra obtained for the two cell lines did not reveal any significant increase in misincorporation of dCTP, the nucleotide in excess, in 707BUF (TK(-)) cells, during DNA replication synthesis. These data suggest that the dCTP:dTTP pool imbalance does not alter the fidelity of DNA replication synthesis in 707BUF (TK(-)) FEL cells. Rather, the predominance of GC --> AT transitions (53%) in the 707BUF (TK(-)) spectrum may reflect a reduced efficiency of repair by uracil DNA glycosylase of uracil residues within these cells.