FK228 potentiates topotecan activity against small cell lung cancer cells via induction of SLFN11.

The response rate of topotecan, as a second-line chemotherapeutic drug for small cell lung cancer, is ~20%. DNA/RNA helicase SLFN11 (schlafen family member 11), a member of the Schlafen (SLFN) family, is a crucial determinant of response to many DNA damaging agents, expression of SLFN11 tends to augment the antitumor effects of the commonly used DNA-targeting agents. In the present study we investigated how SLFN11 expression regulated the sensitivity of small cell lung cancer to topotecan. We showed that SLFN11 expression levels were positively associated with the sensitivity to topotecan in a panel of seven SCLC cell lines. Topotecan treatment induced different patterns of the DNA response network in SCLC cells: DNA damage response (DDR) was more prominently activated in SLFN11-deficient SCLC cell line H82 than in SLFN11-plentiful SCLC cell line DMS273, whereas topotecan induced significant accumulation of p-Chk1, p-RPA2 and Rad51 in H82 cells, but not in DMS273 cells. We unraveled that SLFN11 expression was highly negatively correlated to the methylation of the SLFN11 promoter. HDAC inhibitors FK228 and SAHA dose-dependently increased SLFN11 expression through suppressing DNA methylation at the SLFN11 promoter, thereby sensitizing SCLC cells to topotecan. Finally, we assessed the methylation status of the SLFN11 promoter in 27 SCLC clinical specimens, and found that most of the clinical samples (24/27) showed DNA methylation at the SLFN11 promoter. In conclusion, it is feasible to combine topotecan with FK228 to improve the response rate of topotecan in SCLC patients.

Combinations of proteasome inhibitors with obatoclax are effective for small cell lung cancer.

Proteasome inhibitors, bortezomib (BTZ), and carfilzomib (CFZ) are approved drugs for hematological malignancies, but lack anticancer activities against most solid tumors. Small cell lung cancer (SCLC) is a very aggressive neuroendocrine carcinoma of the lungs demanding effective therapy. In this study we investigated whether BTZ or CFZ combined with obatoclax (OBX), an antagonist for MCL-1 and a pan-BCL family inhibitor, could cause synergistic growth inhibition of SCLC cells. We showed that combined application of BTZ or CFZ with OBX caused synergistic growth inhibition of human SCLC cell lines (H82, H526, DMS79, H196, H1963, and H69) than single agent alone. Both BTZ-OBX and CFZ-OBX combinations displayed marked synergism on inducing apoptosis (~50% increase vs BTZ or CFZ alone). A comprehensive proteomics analysis revealed that BTZ preferentially induced the expression of MCL-1, an antiapoptotic protein, in SCLC cells. Thus, proteasome inhibitor-OBX combinations could specifically induce massive growth inhibition and apoptosis in SCLC cells. Subsequent proteome-wide profiling analysis of activated transcription factors suggested that BTZ- or CFZ-induced MCL-1 upregulation was transcriptionally driven by FOXM1. In nude mice bearing in SCLC H82 xenografts, both BTZ-OBX, and CFZ-OBX combinations exhibited remarkable antitumor activities against SCLC tumors evidenced by significant reduction of tumor size and the proliferation marker Ki-67 signals in tumor tissues as compared with single agent alone. Thus, proteasome inhibitor-OBX combinations are worth immediate assessments for SCLC in clinical settings.

[Relationships of wheat seed vigor with enzyme activities and gene expression related to seed germination under stress conditions.] / é€†å¢ƒæ¡ä»¶ä¸‹å°éº¦ç§å­æ´»åŠ›ä¸Žç§å­èŒå‘ç›¸å ³é ¶æ´»æ€§åŠå ¶åŸºå› è¡¨è¾¾çš„å ³ç³».

This study aimed to analyze the enzyme activities and gene expression differences related to seed germination in different wheat genotypes, and to clarify the relationship between seed vigor and the related enzyme activities as well as gene expression under stress germination conditions. We measured seed vigor, total soluble sugar content, soluble protein content, α-amylase activity, cysteine protease activity and gene expression of the related enzymes of four wheat cultivars under drought, artificial aging and cold soaking stress. Results showed that drought, artificial aging and cold soaking stress affected seed vigor to some extent. Under different germination conditions, total soluble sugar content showed an increasing trend with small amplitude at first and then decreased with small amplitude and after that increased rapidly again, while soluble protein content in the four cultivars gradually decreased with germination time. The α-amylase activity of the four cultivars showed a rising trend on the whole, but that of Yunong 949 and Lunxuan 061 declined after germinating for 60 hours after cold soaking stress. Cysteine protease activity decreased at first and then increased as a whole. However, under drought stress condition, cysteine protease activity of Yunong 949, Yumai 49-198 and Lunxuan 061 increased at first and then decreased and finally increased again. The α-AMY (α-amylase gene) expression levels increased at first and then decreased as a whole under different germination conditions. The expression level of α-AMY in Lunxuan 061 after cold soaking stress was higher than that of CK, while the α-AMY expression levels in four cultivars under other stress germination conditions were lower than that of CK. The expression level of CP (cysteine protease gene) showed an increasing trend. No significant difference of CP expression level was found in Chang 4738 between artificial aging treatment and CK. The CP expression levels in the four cultivars under other stress conditions were higher than that of CK. The results demonstrated that there was no direct relationship between the enzyme activities and gene expression levels of α-amylase and cysteine protease under different germination conditions. The α-amylase activity and total soluble sugar content had an extremely significant positive correlation, but the correlation between cysteine protease activity and soluble protein content was not significant. The α-amylase activity significantly positively correlated with vigor index under standard germination condition. However, the α-amylase activity had no significant correlation with vigor index under stress conditions. After cold soaking stress, cysteine protease activity significantly positively correlated with vi-gor index during seed germination, but the correlation was not significant under standard germination, drought stress and artificial aging.

Peripheral type I interferon receptor correlated with oxidative stress in chronic hepatitis B virus infection.

Type I interferon receptor (IFNAR) has been involved in the progression of chronic hepatitis B (CHB). Oxidative stress is also associated with hepatitis B virus (HBV) infection and might contribute to the structure and function of protein synthesis including the IFNAR family. This study was aimed to determine the possible associations between oxidative stress and peripheral IFNAR expression in chronic HBV infection. Fifty-four CHB patients and 31 liver cirrhosis (LC) patients were consecutively collected, as well as 11 healthy subjects as controls. Expression levels of IFNAR1 and IFNAR2 in peripheral blood lymphocytes and monocytes were measured by flow cytometry. IFNAR1 and IFNAR2c mRNA were detected by real-time reverse transcription-polymerase chain reaction. Levels of plasma-soluble IFNAR and oxidative stress parameters, including xanthine oxidase (XOD), malondialdehyde (MDA), glutathione (GSH), glutathione S-transferase (GST), and glutathione peroxidase (GSH-Px) were detected by enzyme linked immunosorbent assay (ELISA). The frequencies of IFNAR1 and IFNAR2 in lymphocytes and monocytes were significantly increased in CHB and LC patients than in healthy controls. Expression levels of IFNAR1 and IFNAR2c mRNA and plasma-soluble IFNAR level in CHB and LC patients were upregulated compared with healthy controls. Mean fluorescence intensity (MFI) of IFNAR2 in monocytes of CHB patients was higher than that in LC patients. Levels of plasma XOD, MDA, and GST were significantly increased in CHB and LC patients compared with healthy controls. Meanwhile, GSH and GSH-Px in CHB and LC patients were decreased than that in healthy controls. Furthermore, plasma MDA, GSH, and GST levels in CHB patients were higher than that in LC patients. In CHB patients, plasma GST level was negatively correlated with MFI of IFNAR2 in lymphocytes. Our results suggested that oxidative stress play an important role in the regulation of IFNAR in chronic HBV infection.