Oliver G. Opitz

Transactivation of the human keratin 4 and Epstein-Barr virus ED-L2 promoters by gut-enriched Krüppel-like factor.

The Krüppel-like family of transcription factors comprises genes that appear to have tissue-restricted functions. Expression of gut-enriched Krüppel-like factor (GKLF) may be important in the switch from proliferation to differentiation in the squamous epithelium. We sought to determine transcriptionally mediated effects of GKLF on two promoters active in the esophageal squamous epithelium, namely the Epstein-Barr virus ED-L2 and human keratin 4 promoters. Both promoters contain a CACCC-like motif previously shown to bind GKLF. To determine whether GKLF regulates genes containing this element, we first demonstrated expression and then cloned the full-length human GKLF from an esophageal squamous carcinoma cell line. In a transient transfection system, GKLF increased the activity of both promoters >25-fold, localized to regions containing the CACCC-like element. Recombinant GKLF specifically binds the CACCC-like motif in both promoters. GKLF epitope-tagged protein leads to the formation of two proteins of 65 and 34 kDa. The chromatographically purified 65-kDa protein binds the CACCC-like element from both Epstein-Barr virus ED-L2 and keratin 4 promoters, which is not attenuated by the 34-kDa protein. In summary, GKLF is expressed in esophageal squamous epithelial cells and transcriptionally activates two esophageal epithelial promoters important at the transition toward differentiation.

Cyclin D1 overexpression and p53 inactivation immortalize primary oral keratinocytes by a telomerase-independent mechanism

The immortalization of human cells is a critical step in multistep carcinogenesis. Oral-esophageal carcinomas, a model system to investigate molecular mechanisms underlying squamous carcinogenesis, frequently involve cyclin D1 overexpression and inactivation of the p53 tumor suppressor. Therefore, our goal was to establish the functional role of cyclin D1 overexpression and p53 inactivation in the immortalization of primary human oral squamous epithelial cells (keratinocytes) as an important step toward malignant transformation. Cyclin D1 overexpression alone was found to induce extension of the replicative life span of normal oral keratinocytes, whereas the combination of cyclin D1 overexpression and p53 inactivation led to their immortalization. This study also demonstrates that immortalization of oral keratinocytes can be independent of telomerase activation, involving an alternative pathway of telomere maintenance (ALT).

Creating oral squamous cancer cells: A cellular model of oral–esophageal carcinogenesis

Immortalization and malignant transformation are important steps in tumor development. The ability to induce these processes from normal human epithelial cells with genetic alterations frequently found in the corresponding human cancer would significantly enhance our understanding of tumor development. Alterations in several key intracellular regulatory pathways (the pRB, p53, and mitogenic signaling pathways and the telomere maintenance system) appear to be sufficient for the neoplastic transformation of normal human cells. Nevertheless, in vitro transformation models to date depend on viral oncogenes, most prominently the simian virus 40 early region, to induce immortalization and malignant transformation of normal human epithelial cells. Here, we demonstrate a transformation model creating oral–esophageal cancer cells by using a limited set of genetic alterations frequently observed in the corresponding human cancer. In a stepwise model, cyclin D1 overexpression and p53 inactivation led to immortalization of oral keratinocytes. Additional ectopic epithelial growth factor receptor overexpression followed by c-myc overexpression as well as consecutive reactivation of telomerase induced by epithelial growth factor receptor sufficed to transform oral epithelial cells, truly recapitulating the development of the corresponding human disease.

Dual function of the epithelial specific ets transcription factor, ELF3, in modulating differentiation.

The ets family of transcription factors comprises many members which contribute to diverse cellular functions that vary depending upon the cell- and tissue-type context. Recently, different groups have identified a novel member of the ets family that is epithelial-specific. Variably called ESE-1, ERT, jen, ESX, this gene is designated currently as ELF3. In order to understand transcriptional regulatory mechanisms mediated by ELF3, we investigated its effect on the human keratin 4 gene promoter based upon the role of keratin 4 in early differentiation of the esophageal squamous epithelium. Interestingly, ELF3 suppressed basal keratin 4 promoter activity in both esophageal and cervical epithelial cancer cell lines, a novel result, while simultaneously activating the late-differentiation linked SPRR2A promoter. Furthermore, serial deletion constructs of the keratin 4 promoter continued to be suppressed by ELF3, a phenomenon that was only partially rescued by ELF3 ets domain mutants, but completely abrogated by deletion of the ELF3 pointed domain. These results suggest that ELF3 may have dual functions in the transcriptional regulation of genes involved in squamous epithelial differentiation. One of these functions may not be exclusively mediated through DNA binding in the context of transcriptional suppression of the keratin 4 promoter.

CYTOKINE GENE EXPRESSION IN IMMUNE MICE REINFECTED WITH MYCOPLASMA PNEUMONIAE : THE ROLE OF T CELL SUBSETS IN AGGRAVATING THE INFLAMMATORY RESPONSE

Cytokine gene expression was examined by qualitative and semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) in the lungs of Mycoplasma pneumoniae infected immune C57BL/6 mice depleted of either CD4+, CD8+ or both CD4+ and CD8+ T cells. Immediately after M. pneumoniae reinfection of control immune mice, mRNAs for TNF-alpha, IFN-gamma, IL-1 beta, IL-6, IL-2 and IL-2 receptor were promptly detected in the lungs. In animals depleted of CD4+ T cells, mRNA expression for IL-2, IL-2 receptor and IFN-gamma were completely abrogated and mRNA expression for TNF-alpha, IL-1 beta and IL-6 were reduced by 10- to 100-fold. In mice depleted of CD8+ T cells, mRNA expression for IL-2 and the IL-2 receptor was also undetectable, while mRNA for TNF-alpha, IL-1 beta and IL-6 were only marginally decreased. Histological evaluation of the infected lungs performed in parallel revealed dense mononuclear infiltrations around small bronchi and small blood vessels in control reinfected mice. In contrast, in CD4+ T cell-depleted mice, these focal accumulation of lung tissue infiltrating cells were found to be greatly reduced. The data indicate that the inflammatory response in lung tissue thought to be mainly responsible for Mycoplasma pneumoniae disease is associated with an increased level and a prolonged expression of proinflammatory cytokines due to CD4+ lung infiltrating T cells.

Ha-Ras(G12V) induces senescence in primary and immortalized human esophageal keratinocytes with p53 dysfunction.

Oncogenic Ras induces premature senescence in primary cells. Such an oncogene-induced senescence involves activation of tumor suppressor genes that provide a checkpoint mechanism against malignant transformation. In mouse, the ARF–p53 pathway mediates Ha-RasG12V-induced senescence, and p19ARF−/− and p53−/− cells undergo transformation upon Ras activation. In addition, mouse cells, unlike human cells, express constitutively active telomerase and have long telomeres. However, it is unclear how Ras activation affects human cells of epithelial origin with p53 mutation and/or telomerase activation. In order to address this question, Ha-RasG12V was expressed ectopically in primary as well as hTERT-immortalized human esophageal keratinocytes stably expressing dominant-negative p53 mutants. In human esophageal keratinocytes, we found that Ha-RasG12V induced senescence regardless of p53 status and telomerase activation. Ras activation resulted in changes of cellular morphology, activation of senescence-associated β-galactosidase, and suppression of cell proliferation, all coupled with reduction in the hyperphosphorylated form of the retinoblastoma protein (pRb). Furthermore, Ha-RasG12V upregulated p16INK4a and downregulated cyclin-dependent kinase Cdk4 in human esophageal keratinocytes. Thus, Ras-mediated senescence may involve distinct mechanisms between human and mouse cells. Inactivation of the pRb pathway may be necessary for Ras to overcome senescence and transform human esophageal epithelial cells.

EGFR overexpression induces activation of telomerase via PI3K/AKT-mediated phosphorylation and transcriptional regulation through Hif1-alpha in a cellular model of oral–esophageal carcinogenesis

Telomerase plays an important role during immortalization and malignant transformation as crucial steps in the development of human cancer. In a cellular model of oral–esophageal carcinogenesis, recapitulating the human disease, immortalization occurred independent of the activation of telomerase but through the recombination‐based alternative lengthening of telomeres (ALT). In this stepwise model, additional overexpression of EGFR led to in vitro transformation and activation of telomerase with homogeneous telomere elongation in already immortalized oral squamous epithelial cells (OKF6‐D1_dnp53). More interestingly, EGFR overexpression activated the PI3K/AKT pathway. This strongly suggested a role for telomerase in tumor progression in addition to just elongating telomeres and inferring an immortalized state. Therefore, we sought to identify the regulatory mechanisms involved in this activation of telomerase and in vitro transformation induced by EGFR. In the present study we demonstrate that telomerase expression and activity are induced through both direct phosphorylation of hTERT by phospho‐AKT as well as PI3K‐dependent transcriptional regulation involving Hif1‐alpha as a key transcription factor. Furthermore, EGFR overexpression enhanced cell cycle progression and proliferation via phosphorylation and translocation of p21. Whereas immortalization was induced by ALT, in vitro transformation was associated with telomerase activation, supporting an additional role for telomerase in tumor progression besides elongating telomeres. (Cancer Sci 2011; 102: 351–360)

Prognostic Relevance of Carbohydrate Antigen 19-9 Levels in Patients with Advanced Biliary Tract Cancer

Serum carbohydrate antigen 19-9 (CA 19-9) has been identified as biochemical marker for biliary tract cancer (BTC). The purpose of this study was to evaluate its value as a treatment response marker and its value as a prognostic parameter in patients with unresectable BTC. We analyzed 70 patients with BTC treated with chemotherapy. CA 19-9 levels before and after two treatment courses were analyzed with respect to their effect on treatment response. Patients were categorized into two subgroups according to biliary stenting: patients without endoscopic intervention or biliary drainage (non-stent subgroup) and patients with endoluminal stenting (stent subgroup). Pretreatment CA 19-9 levels were prognostic with respect to overall survival for the entire study population. Patients with CA 19-9 levels above the median of 300 units/mL had a nearly 3-fold risk for early death (hazard ratio, 2.92; 95% confidence interval, 1.51-5.64; adjusted P = 0.002) as compared with patients with CA 19-9 levels ≤300 units/mL. An association between CA 19-9 and therapeutic response was observed in the non-stent subgroup (P = 0.001) only. Furthermore, the decrease of CA 19-9 levels after treatment was predictive for improved survival in the non-stent subgroup (adjusted P = 0.018) but not in the stent subgroup. Our results indicate that pretreatment CA 19-9 levels and CA 19-9 decrease after chemotherapy are of prognostic relevance in patients with BTC. (Cancer Epidemiol Biomarkers Prev 2007;16(10):2097–100)

Telomere dysfunction and loss of p53 cooperate in defective mitotic segregation of chromosomes in cancer cells

Aneuploidy is a fundamental principle of many cancer cells and is mostly related to defects in mitotic segregation of chromosomes. Many solid tumors as well as some preneoplastic lesions have been shown to contain polyploid chromosome numbers. The exact mechanisms behind whole-genome duplications are not known but have been linked to compromised mitotic checkpoint genes. We now report that the telomere checkpoint plays a key role for polyploidy in colon cancer cells. Telomerase suppression by a dominant-negative mutant of hTERT and consecutive telomere dysfunction in wild-type HCT116 colon cancer cells resulted in only minor stable chromosomal alterations. However, higher ploidy levels with up to 350 chromosomes were found when the cell-cycle checkpoint proteins p53 or p21 were absent. These findings indicate that telomere dysfunction in the absence of cell-cycle control may explain the high frequency of alterations in chromosome numbers found in many solid tumors.

Results of a randomized controlled pilot study of a self-management intervention for cancer pain.

PURPOSE OF THE RESEARCH This paper reports findings from a randomized controlled pilot study evaluating the PRO-SELF Plus Pain Control Program, a U.S.-developed cancer pain self-management intervention, regarding feasibility and effect sizes in a German patient sample. METHODS AND SAMPLE Thirty-nine German oncology outpatients were randomized to intervention (n = 19) and control (n = 20) groups. The intervention group received the PRO-SELF Plus Pain Control Program in 6 visits and 4 phone calls a 10-week period. The control group received standard education and care. The intervention employed three key strategies: information provision, skills building, and nurse coaching. Primary outcomes were changes in average and worst pain intensity. Secondary outcomes included changes in pain-related knowledge, opioid intake, and self-efficacy. Data were collected at enrollment, then at 6, 10, 14, and 22 weeks. KEY RESULTS The group-by-time effect showed a statistically significant increase in knowledge (week 10: p = 0.04; week 22: p < 0.01). Despite slight reductions in average and worst pain, no statistically significant changes were found for pain, opioid intake, or self-efficacy. CONCLUSIONS This study is the first to evaluate and demonstrate the feasibility of a U.S.-developed cancer pain self-management intervention in a German patient population. Pain self-management related knowledge improved significantly and effect sizes for pain reduction were determined. Findings from this pilot RCT provide the basis for planning a larger RCT. CLINICAL TRIAL REGISTRATION NUMBER NCT00920504.