Purpose: Programmed cell death 4 (Pdcd4) is a novel tumor suppressor gene which is known to act as a negative regulator of protein translation and malignant transformation. However, the tumor suppressor mechanism of Pdcd4 remain unclear. In order to elucidate the mechanism of inhibition of tumor malignancy by Pdcd4, we conducted the knockdown of Pdcd4 in cells.

Methods: In this study, we used three mouse cell lines. The C57BL/6J-emb and the NIH3T3 are normal fibroblast cells, the B16-F0 are low-metastatic melanoma cells. We established the Pdcd4 knockdown cells using siRNA systems. mRNA was extracted from Pdcd4 knockdown C57BL/6J-emb and B16-F0, we performed DNA microarray analysis. To confirm the results of microarray analysis, we performed real-time PCR analysis.

Results: The mRNA levels of Pdcd4 in each cell line were significantly decreased after 24 hr or 48 hr exposure to siPdcd4. Among 23,474 mouse genes, microarray analysis identified 3 significantly up-regulated and 10 significantly down-regulated genes in both Pdcd4 knockdown C57BL6J-emb and B16-F0 (ratio>=2 [up and down]). Real-time PCR showed that the mRNA levels of Skp2 which was identified down-regulated gene, significantly decreased in Pdcd4 knockdown C57BL/6J-emb and NIH3T3 compared with the control cells.

Summary/Conclusion: These results suggest that Skp2 might be one of genes involved in the tumor suppression by Pdcd4.

Oyster (Crassostrea gigas) contains abundant nutritional elements, including glycogen, vitamine, zinc and taurine. It is reported that oyster extract exhibited several physiological activities．In this study, the symptom relieving effects of oyster extracts on 5-fluorouracil (5-FU) induced toxicity in rats was examined mainly on gastrointestinal toxicity and myelotoxicity.

Male SD rats were used in this study. Test groups were as follow, control, 5-FU, 5-FU and oyster extract (200 and 500 mg/kg/days). Oyster extracts were administrated for 21 days in rats. 5-FU was administrated for 5 days after 14 days of oyster extracts administrated. After termination of administration of oyster extracts, recovery period was established for 3 days, and autopsy was performed.

No deaths were observed throughout the study period. Regarding body weight and food intake, significant reduction suppression and dose-dependent reduction tendency was observed. In the hematological examination, influence was observed on the white blood cell count, red blood cell count, hemoglobin amount and hematocrit value due to administration of 5-FU.

Evaluation of intestinal mucosa by histopathological examination, mucosal thickness, villous height and crypt thickness were dose - dependent or high trend without dose - dependence. In addition, a suppression tendency was also observed for mucosal atrophy of the duodenum due to administration of 5-FU. From the above results, it was suggested that oyster extract is effective in alleviating gastrointestinal toxicity by 5-FU.

Baloxavir marboxil is an oral prodrug that is rapidly converted to its active form baloxavir acid, a potent inhibitor of influenza cap-dependent endonuclease function of influenza A and B viruses. Baloxavir was approved for treatment of uncomplicated influenza A and B virus infections in 2018 in Japan (for those weighing >10 kg) and the United States (for those aged 12 years and older)

Key nonclinical characteristics of baloxavir include broad spectrum activity against various types and subtypes of influenza virus strains in vitro as well as rapid and profound reduction in viral load in vivo. The phase III study (CAPSTONE-1) was a multicenter, randomised, double-blind, placebo- and oseltamivir-controlled study of otherwise-healthy patients in Japan and US (n=1436). The primary endpoint was time to alleviation of influenza symptoms (TTAS). TTAS was shorter with baloxavir than placebo (median 53.7 hr vs 80.2 hr, p<0.0001). Median time to cessation of viral shedding was 24 hr in baloxavir-treated patients, compared with 72 hr for oseltamivir (p<0.0001) and 96 hr for placebo (p<0.0001). Baloxavir was well tolerated and appeared to have no significant safety issues identified. Testing of laboratory isolates passage or clinical isolates identified isoleucine-to-threonine substitution at amino acid position 38 in N-terminal domain (PA/I38T). PA/I38 substitutions conferred reduced susceptibility to baloxavir and reduced fitness in variants. In the poster session, we report the key nonclinical and clinical profiles of baloxavir.

Anti-cholinergic inhibitors have been used for the treatment of chronic obstructive pulmonary disease (COPD). Because of their side effects, there is a big demand for new type of drugs. Su et al., (Nature Commun, 2013) has proposed a hypothesis that prothymosin α (ProTα) upregulated in emphysema patients binds to histone H1 and eliminates the histone deacetylase (HDAC) bound to H1, leading to an epigenetic upregulation of matrix metalloprotease (MMP) gene expression, which may cause pulmonary cell damage. In addition, Borge et al., (Nature, 2018) demonstrated that ProTα binds to H1 at a picomolar level of Kd value. Based on these reports we attempted to find inhibitors of ProTα-H1 interaction by use of homogenous time-resolved fluorescence (HTRF). Using an existing drug compound library (～2300 compound), we obtained benserazide, which inhibits the interaction by 70% at 30 μM. Although it is under investigation whether benserazide has beneficial actions against the toxicity of cigarette smoking extract (CSE) or its constituents, here we will present following findings, as follows; 1) ProTα gene expression is very high in A549 lung cancer cells, 2) the treatment with siRNA ProTα gene down-regulated the expression of MMP2 gene as well as ProTα gene in A549 cells, 3) benserazide alone has no action, but it deteriorated the CSE-induced damage of survival activity of A549 cells, 4) from the RNAseq analysis of lung, which has been treated with CSE (i.v,) for 6 weeks, it was found that some candidate genes involved in CSE-induced toxicity and its reversibility by benserazide.