A distinct role for interleukin-6 as a major mediator of cellular adjustment to an altered culture condition.

Tissue microenvironment adjusts biological properties of different cells by modulating signaling pathways and cell to cell interactions. This study showed that epithelial-mesenchymal transition (EMT)/ mesenchymal-epithelial transition (MET) can be modulated by altering culture conditions. HPV E6/E7-transfected immortalized oral keratinocytes (IHOK) cultured in different media displayed reversible EMT/MET accompanied by changes in cell phenotype, proliferation, gene expression at transcriptional, and translational level, and migratory and invasive activities. Cholera toxin, a major supplement to culture medium, was responsible for inducing the morphological and biological changes of IHOK. Cholera toxin per se induced EMT by triggering the secretion of interleukin 6 (IL-6) from IHOK. We found IL-6 to be a central molecule that modulates the reversibility of EMT based not only on the mRNA level but also on the level of secretion. Taken together, our results demonstrate that IL-6, a cytokine whose transcription is activated by alterations in culture conditions, is a key molecule for regulating reversible EMT/MET. This study will contribute to understand one way of cellular adjustment for surviving in unfamiliar conditions.

Nasopharyngeal pneumococcal carriage of children attending day care centers in Korea: comparison between children immunized with 7-valent pneumococcal conjugate vaccine and non-immunized.

To confirm the effect of 7-valent pneumococcal conjugate vaccine (PCV7), pneumococcal nasopharyngeal (NP) carriage was compared between vaccinated (3 + 1 doses PCV7) and non-vaccinated children. Vaccinated subjects were recruited from highly vaccinated regions (≥ 60%), Seoul and Incheon whereas control subjects were recruited from Jeju Island where vaccination rates are low (< 15%). NP swabs were obtained from 400 children aged 18-59 months. Serotype and antibiotic susceptibility was analyzed. Pneumococcal carriage rate was 18.0% (36/200) and 31.5% (63/200) for the vaccinated and control group, respectively. Among those vaccinated, 41.7% (15/36) of the serotypes were vaccine-related type (VRT: 6A, 6C, 19A) with the most common serotype 6C. The next common type was non-typable/non-capsule 30.6% (11/36) followed by non-vaccine type 16.7% (6/36) and vaccine type (VT) serotypes were found in only 11.1% (4/36). In contrast, 52.4% (33/63) of the isolates in the control group were VT. Resistance rates for penicillin and erythromycin were lower in the vaccine group (vaccine vs control; penicillin 45.2% vs 71.4%, erythromycin 74.2% vs 90.5%, P < 0.05). Multi-drug resistance was also lower in vaccinated subjects (vaccine vs control; 45.2% vs 69.8%, P < 0.05). PCV7 reduces carriage in VT which leads to replacement of pneumococci by antibiotic susceptible VRT or non-vaccine type strains.

Chemical targeting of GAPDH moonlighting function in cancer cells reveals its role in tubulin regulation.

Glycolytic enzymes are attractive anticancer targets. They also carry out numerous, nonglycolytic "moonlighting" functions in cells. In this study, we investigated the anticancer activity of the triazine small molecule, GAPDS, that targets the glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH). GAPDS showed greater toxicity against cancer cells compared to a known GAPDH enzyme inhibitor. GAPDS also selectively inhibited cell migration and invasion. Our analysis showed that GAPDS treatment reduced GAPDH levels in the cytoplasm, which would modulate the secondary, moonlighting functions of this enzyme. We then used GAPDS as a probe to demonstrate that a moonlighting function of GAPDH is tubulin regulation, which may explain its anti-invasive properties. We also observed that GAPDS has potent anticancer activity in vivo. Our study indicates that strategies to target the secondary functions of anticancer candidates may yield potent therapeutics and useful chemical probes.

A novel zebrafish human tumor xenograft model validated for anti-cancer drug screening.

The development of a relatively simple, reliant and cost-effective animal test will greatly facilitate drug development. In this study, our goal was the establishment of a rapid, simple, sensitive and reproducible zebrafish xenograft model for anti-cancer drug screening. We optimized the conditions for the cancer cell xenograft in terms of injected cell numbers, incubation temperature and time. A range of human carcinoma cell types were stained with a fluorescent dye prior to injection into the fish larvae. Subsequent cancer cell dissemination was observed under fluorescent microscopy. Differences in injected cell numbers were reflected in the rate of dissemination from the xenograft site. Paclitaxel, known as a microtubule stabilizer, dose-dependently inhibited cancer cell dissemination in our zebrafish xenograft model. An anti-migratory drug, LY294002 (phosphatidylinositol 3-kinase inhibitor) also decreased the cancer cell dissemination. Chemical modifications to increase cancer drug pharmacokinetics, such as increased solubility (17-DMAG compared to geldanamycin) could also be assessed in our xenograft model. In addition to testing our new model using known anti-cancer drugs, we carried out further validation by screening a tagged triazine library. Two novel anti-cancer drug candidates were discovered. Therefore, our zebrafish xenograft model provides a vertebrate animal system for the rapid screening and pre-clinical testing of novel anti-cancer agents, prior to the requirement for testing in mammals. Our model system should greatly facilitate drug development for cancer therapy because of its speed, simplicity and reproducibility.

A triazine compound S06 inhibits proinvasive crosstalk between carcinoma cells and stromal fibroblasts via binding to heat shock protein 90.

Carcinoma-associated fibroblasts (CAFs) promote tumor invasion by secreting soluble factors. A tagged triazine library was screened in our novel transwell coculture model of CAF and oral squamous cell carcinoma (OSCC). We discovered compound S06, which reduced OSCC invasion by inhibiting secretion of CAF-derived proinvasive chemokines. The N-terminus of Hsp90 was found to be the cellular target of S06. Importantly, S06 did not induce hepatic toxicity, a side effect associated with well-known Hsp90 inhibitors. Moreover, S06 inhibited tumor cell migration in a zebrafish xenograft model. Our results demonstrate that Hsp90 is a novel target for stromal-based therapy to modulate proinvasive molecular crosstalk within the tumor microenvironment. Furthermore, S06 represents a new class of Hsp90 inhibitor and is an attractive candidate for anticancer drug development.