Altered mRNA expression levels of autophagy- and apoptosis-related genes in the FOXO pathway in schizophrenia patients treated with olanzapine.

This study attempted to analyze the alterations in the mRNA expression levels of autophagy- and apoptosis-related genes in the forkhead box transcription factor O (FOXO) pathway in schizophrenia patients before and after olanzapine treatment. For a total of 32 acute schizophrenic inpatients, clinical data with PANSS were obtained before and after four weeks of olanzapine treatment (mean dose 14.24 ± 4.35 mg/d) along with data from 32 healthy volunteers. The mRNA expression levels of the FOXO pathway genes were measured by real-time qPCR after fasting venous blood was collected and analyzed. The mRNA expression levels of FOXO1, FOXO3A, FASLG, and BCL2L11 were observed to be significantly decreased in acute schizophrenia patients. After four weeks of olanzapine treatment, the expression levels of the first three genes were further reduced, but BCL2L11 expression levels were not significantly changed. The pairwise correlations between the mRNA expression level of FASLG and those of the other three genes were not observed in acute schizophrenia patients, while these relationships were observed in healthy controls. After olanzapine treatment, the FASLG mRNA expression level was restored and exhibited a pairwise correlation with the FOXO3A and BCL2L11 mRNA expression levels but not with the FOXO1 mRNA expression level, and FASLG mRNA expression was also correlated with the duration of the disease. The statuses and correlations of the mRNA expression levels of FOXO pathway-related genes were altered in schizophrenia patients and were affected by olanzapine treatment and the duration of the disease.

Glucocorticoids enhance the antileukemic activity of FLT3 inhibitors in FLT3-mutant acute myeloid leukemia.

FLT3 is a frequently mutated gene that is highly associated with a poor prognosis in acute myeloid leukemia (AML). Despite initially responding to FLT3 inhibitors, most patients eventually relapse with drug resistance. The mechanism by which resistance arises and the initial response to drug treatment that promotes cell survival is unknown. Recent studies show that a transiently maintained subpopulation of drug-sensitive cells, so-called drug-tolerant "persisters" (DTPs), can survive cytotoxic drug exposure despite lacking resistance-conferring mutations. Using RNA sequencing and drug screening, we find that treatment of FLT3 internal tandem duplication AML cells with quizartinib, a selective FLT3 inhibitor, upregulates inflammatory genes in DTPs and thereby confers susceptibility to anti-inflammatory glucocorticoids (GCs). Mechanistically, the combination of FLT3 inhibitors and GCs enhances cell death of FLT3 mutant, but not wild-type, cells through GC-receptor-dependent upregulation of the proapoptotic protein BIM and proteasomal degradation of the antiapoptotic protein MCL-1. Moreover, the enhanced antileukemic activity by quizartinib and dexamethasone combination has been validated using primary AML patient samples and xenograft mouse models. Collectively, our study indicates that the combination of FLT3 inhibitors and GCs has the potential to eliminate DTPs and therefore prevent minimal residual disease, mutational drug resistance, and relapse in FLT3-mutant AML.

GLCCI1 is a novel protector against glucocorticoid-induced apoptosis in T cells.

Glucocorticoids (GCs) potently induce T-cell apoptosis in a GC receptor (GR)-dependent manner and are used to control lymphocyte function in clinical practice. However, its downstream pathways remain controversial. Here, we showed that GC-induced transcript 1 (GLCCI1) is a novel downstream molecule of the GC-GR cascade that acts as an antiapoptotic mediator in thymic T cells. GLCCI1 was highly phosphorylated and colocalized with microtubules in GLCCI1-transfected human embryonic kidney QBI293A cells. GR-dependent up-regulation of GLCCI1 was associated with GC-induced proapoptotic events in a cultured thymocyte cell line. However, GLCCI1 knockdown in a thymocyte cell line led to apoptosis. Consistently, transgenic mice overexpressing human GLCCI1 displayed enlarged thymi that consisted of larger numbers of thymocytes. Further molecular characterization showed that GLCCI1 bound to both dynein light chain LC8-type 1 (LC8) and its functional kinase, p21-protein activated kinase 1 (PAK1), thereby inhibiting the kinase activity of PAK1 toward LC8 phosphorylation, a crucial event in apoptotic signaling. GLCCI1 induction facilitated LC8 dimer formation and reduced Bim expression. Thus, GLCCI1 is a candidate factor involved in apoptosis regulation of thymic T cells.-Kiuchi, Z., Nishibori, Y., Kutsuna, S., Kotani, M., Hada, I., Kimura, T., Fukutomi, T., Fukuhara, D., Ito-Nitta, N., Kudo, A., Takata, T., Ishigaki, Y., Tomosugi, N., Tanaka, H., Matsushima, S., Ogasawara, S., Hirayama, Y., Takematsu, H., Yan, K. GLCCI1 is a novel protector against glucocorticoid-induced apoptosis in T cells.

Mouse ER+/PIK3CAH1047R breast cancers caused by exogenous estrogen are heterogeneously dependent on estrogen and undergo BIM-dependent apoptosis with BH3 and PI3K agents.

Estrogen dependence is major driver of ER + breast cancer, which is associated with PI3K mutation. PI3K inhibition (PI3Ki) can restore dependence on ER signaling for some hormone therapy-resistant ER + breast cancers, but is ineffective in others. Here we show that short-term supplementation with estrogen strongly enhanced Pik3caH1047R-induced mammary tumorigenesis in mice that resulted exclusively in ER + tumors, demonstrating the cooperation of the hormone and the oncogene in tumor development. Similar to human ER + breast cancers that are endocrine-dependent or endocrine-independent at diagnosis, tumor lines from this model retained ER expression but were sensitive or resistant to hormonal therapies. PI3Ki did not induce cell death but did cause upregulation of the pro-apoptotic gene BIM. BH3 mimetics or PI3Ki were unable to restore hormone sensitivity in several resistant mouse and human tumor lines. Importantly however, combination of PI3Ki and BH3 mimetics had a profound, BIM-dependent cytotoxic effect in PIK3CA-mutant cancer cells while sparing normal cells. We propose that addition of BH3 mimetics offers a therapeutic strategy to markedly improve the cytotoxic activity of PI3Ki in hormonal therapy-resistant and ER-independent PIK3CA-mutant breast cancer.

miR-23 regulates cell proliferation and apoptosis of vascular smooth muscle cells in coronary heart disease.

BACKGROUND: Aberrant proliferation and migration of vascular smooth muscle cells (VSMCs) play an important role in the pathogenesis of cardiovascular diseases including coronary heart disease (CHD). MicroRNAs has reported play critical roles in VSMCs function. The present study was to investigate the effects of microRNA­23 (miR-23) on VSMCs and uncover its potential mechanism. METHODS: Cell viability was detected by CCK-8 assay. Cell apoptosis was measured by flow cytometry. Dual luciferase reporter assay was conducted to verify whether BCL2L11 is a target gene of miR-23. The protein levels of BCL2L11 and caspase-3 were detect by quantitative real time PCR and western blot. RESULTS: Our results showed that the expression of miR-23 was upregulated in peripheral blood of CHD patients compared with controls. Overexpression of miR-23 promoted VSMCs proliferation and inhibited VSMCs apoptosis. Downregulation of miR-23 suppressed VSMCs proliferation and promoted VSMCs apoptosis. In addition, we identified BCL2L11 was a direct gene of miR-23. Overexpression of miR-23 decreased the levels of BCL2L11 and caspase-3, and downregulate of miR-23 increased the levels of BCL2L11and caspase-3 in VSMCs. CONCLUSION: Our findings suggest that miR-23 plays a crucial role in controlling VSMCs proliferation and apoptosis by targeting BCL2L11.

Effects of miR-223 on colorectal cancer cell proliferation and apoptosis through regulating FoxO3a/BIM.

OBJECTIVE: Colorectal cancer is a common malignant tumor of the digestive tract. It frequently occurs at the junction of the rectum and sigmoid colon. It is characterized by high mortality and poor prognosis. Bcl-2 interacting mediator of cell death (BIM) plays a role in the regulation of cell proliferation and apoptosis, and involves in the pathogenesis of colorectal cancer. The transcription factor forkhead, transcription factor O subfamily 3a (FoxO3a) plays a role in the regulation of BIM expression and is associated to the pathogenesis of colorectal cancer. Bioinformatics analysis suggests that there is a targeted relationship between FoxO3a and microRNA-223 (miR-223). This study aims to investigate effects of miR-223 on the regulation of FoxO3a/BIM signaling pathway and colorectal cancer cell proliferation and apoptosis. MATERIALS AND METHODS: Colorectal cancer cell line SW620 and normal colorectal epithelial cell line NCM460 were cultured in vitro. Dual luciferase reporter assay was used to validate the relationship between miR-223 and FoxO3a. Flow cytometry was adopted to detect apoptosis. EdU staining was applied to test cell proliferation. Western blot was selected to determine FoxO3a and BIM protein expressions. RESULTS: There was targeted regulatory relationship between miR-223 and FoxO3a. MiRa-223 up-regulated, FoxO3a and BIM expressions reduced, and cell proliferation was enhanced in SW620 cells compared with NCM460 cells. MiR-223 inhibitor or pIRES2-FoxO3a transfection significantly increased FoxO3a and BIM expressions, attenuated cell proliferation, and enhanced cell apoptosis. CONCLUSIONS: MiR-223 targeted inhibited expression of FoxO3. Down-regulating the expression of miR-223, it increased the expressions of FoxO3a and BIM, weakened SW620 cells proliferation and induced apoptosis.

Early changes in rpS6 phosphorylation and BH3 profiling predict response to chemotherapy in AML cells.

Blasts from different patients with acute myeloid leukemia (AML) vary in the agent(s) to which they are most responsive. With a myriad of novel agents to evaluate, there is a lack of predictive biomarkers to precisely assign targeted therapies to individual patients. Primary AML cells often survive poorly in vitro, thus confounding conventional cytotoxicity assays. The purpose of this work was to assess the potential of two same-day functional predictive assays in AML cell lines to predict long-term response to chemotherapy. (i) Ribosomal protein S6 (rpS6) is a downstream substrate of PI3K/akt/mTOR/ kinase and MAPK kinase pathways and its dephosphorylation is also triggered by DNA double strand breaks. Phospho-rpS6 is reliably measurable by flow cytometry and thus has the potential to function as a biomarker of responsiveness to several therapeutic agents. (ii) A cell's propensity for apoptosis can be interrogated via a functional assay termed "Dynamic BH3 Profiling" in which mitochondrial outer membrane permeabilization in drug-treated cells can be driven by pro-apoptotic BH3 domain peptides such as PUMA-BH3. The extent to which a particular cell is primed for apoptosis by the drug can be determined by measuring the amount of cytochrome C released on addition of BH3 peptide. We demonstrate that phospho-rpS6 expression and PUMA-BH3 peptide-induced cytochrome C release after 4 hours both predict long term chemoresponsiveness to tyrosine kinase inhibitors and DNA double strand break inducers in AML cell lines. We also describe changes in expression levels of the prosurvival BCL-2 family member Mcl-1 and the pro-apoptotic protein BIM after short term drug culture.

Bim may be a poor prognostic biomarker in breast cancer patients especially in those with luminal A tumors.

BACKGROUND: Bcl-2 interacting mediator of cell death (Bim) appears to have contradictory roles in cancer. It is uncertain whether Bim show prognostic significance in patients with breast cancer. OBJECTIVE: To investigate the correlation between Bim expression and clinicopathological characteristics of breast cancer and to evaluate Bim's effect on overall survival (OS). METHODS: We used immunohistochemistry (IHC) technique to detect the expression of Bim via tissue microarray in 275 breast cancer samples, Kaplan-Meier analysis to perform survival analysis, and Cox proportional hazards regression model to explore the risk factors of breast cancer. RESULTS: The results revealed that Bim expression was significantly correlated with age, estrogen receptor (ER) and/or progesterone receptor (PR), human epidermal growth factor receptor (HER2) and Ki67 expression (P< 0.05). Bim expression was significantly different in the four molecular subtypes (P= 0.000). Survival analysis showed that Bim positive expression contributed to a shorter OS (P= 0.034), especially in patients with luminal A tumors (P= 0.039). Univariate and multivariate regression analysis showed that Bim was an independent prognostic factor for breast cancer (P< 0.05). CONCLUSION: Bim may serve as an effective predictive factor for lower OS in breast cancer patients, especially in those with luminal A tumors.

Betulinic acid derivative B10 inhibits glioma cell proliferation through suppression of SIRT1, acetylation of FOXO3a and upregulation of Bim/PUMA.

Glioma is the most common primary malignant tumor of the central nervous system. B10 is a new glycosylated derivative of betulinic acid with enhanced cytotoxic activity. The present study was designed to explore the molecular mechanism underlying the anticancer effect of B10 in glioma cells. 25-50µM B10 resulted in a significant decrease of cell viability and BrdU incorporation. 25-50mg/kg B10 significantly reduced the implanted tumor weight and volume in nude mice. Activation of apoptosis was found in glioma cells when the cells were exposed to B10, as evidenced by increased number of TUNEL-stained cells, increased caspase 3 and 9 activities, and Bax and cleaved PARP expression. B10 caused a significant decrease in mitochondrial oxygen consumption rate, mitochondrial complex I, II, III, IV, and V activities, and ATP level, and increase of mitochondrial ROS production, indicating the induction of mitochondrial dysfunction. B10 reduced the expression of sirtuin (SIRT) 1 and resulted in an increase in forkhead box O (FOXO) 3a expression and acetylation. Activation of SIRT1 by SRT-1720 and downregualtion of FOXO3a using shRNA significantly inhibited B10-induced cytotoxicity. B10 markedly increased the expression of Bim and PUMA. Downregualtion of FOXO3a or activation of SIRT1 significantly inhibited B10-induced increase of Bim and PUMA expression. Downregualtion of Bim or PUMA could suppress B10-induced increase of Bax expression. Moreover, B10-induced cytotoxicity was significantly suppressed by downregulation of Bim or PUMA. In summary, we identified B10 as a potent therapeutic candidate for glioma treatment and SIRT1-FOXO3a-Bim/PUMA axis as a novel therapeutic target.

Bruton's tyrosine kinase inhibition increases BCL-2 dependence and enhances sensitivity to venetoclax in chronic lymphocytic leukemia.

Although the BTK inhibitor ibrutinib has transformed the management of patients with chronic lymphocytic leukemia (CLL), it does not induce substantial apoptosis in vitro, and as such the mechanisms underlying its ability to kill CLL cells are not well understood. Acalabrutinib, a more specific BTK inhibitor now in development, also appears to be highly effective in CLL, but the connection of its mechanism with CLL cell death is also unclear. Using dynamic BH3 profiling, we analyzed alterations in the function of the mitochondrial apoptotic pathway induced by ibrutinib and acalabrutinib. We studied CLL patient samples treated ex vivo with both drugs, as well as primary samples from CLL patients on clinical trials of both drugs. We found that BTK inhibition enhances mitochondrial BCL-2 dependence without significantly altering overall mitochondrial priming. Enhancement of BCL-2 dependence was accompanied by an increase in the pro-apoptotic protein BIM. In contrast, treatment with the selective BCL-2 inhibitor venetoclax enhanced overall mitochondrial priming without increasing BCL-2 dependence. Pre-treatment of CLL cells with either BTK inhibitor, whether ex vivo or in vivo in patients, enhanced killing by venetoclax. Our data suggest that BTK inhibition enhances mitochondrial BCL-2 dependence, supporting the ongoing development of clinical trials combining BTK and BCL-2 inhibition.

Targeting BET proteins improves the therapeutic efficacy of BCL-2 inhibition in T-cell acute lymphoblastic leukemia.

Inhibition of anti-apoptotic BCL-2 (B-cell lymphoma 2) has recently emerged as a promising new therapeutic strategy for the treatment of a variety of human cancers, including leukemia. Here, we used T-cell acute lymphoblastic leukemia (T-ALL) as a model system to identify novel synergistic drug combinations with the BH3 mimetic venetoclax (ABT-199). In vitro drug screening in primary leukemia specimens that were derived from patients with high risk of relapse or relapse and cell lines revealed synergistic activity between venetoclax and the BET (bromodomain and extraterminal) bromodomain inhibitor JQ1. Notably, this drug synergism was confirmed in vivo using T-ALL cell line and patient-derived xenograft models. Moreover, the therapeutic benefit of this drug combination might, at least in part, be mediated by an acute induction of the pro-apoptotic factor BCL2L11 and concomitant reduction of BCL-2 upon BET bromodomain inhibition, ultimately resulting in an enhanced binding of BIM (encoded by BCL2L11) to BCL-2. Altogether, our work provides a rationale to develop a new type of targeted combination therapy for selected subgroups of high-risk leukemia patients.

Temporal Expression of Bim Limits the Development of Agonist-Selected Thymocytes and Skews Their TCRß Repertoire.

CD8αα TCRαß+ intestinal intraepithelial lymphocytes play a critical role in promoting intestinal homeostasis, although mechanisms controlling their development and peripheral homeostasis remain unclear. In this study, we examined the spatiotemporal role of Bim in the thymic selection of CD8αα precursors and the fate of these cells in the periphery. We found that T cell-specific expression of Bim during early/cortical, but not late/medullary, thymic development controls the agonist selection of CD8αα precursors and limits their private TCRß repertoire. During this process, agonist-selected double-positive cells lose CD4/8 coreceptor expression and masquerade as double-negative (DN) TCRαßhi thymocytes. Although these DN thymocytes fail to re-express coreceptors after OP9-DL1 culture, they eventually mature and accumulate in the spleen where TCR and IL-15/STAT5 signaling promotes their conversion to CD8αα cells and their expression of gut-homing receptors. Adoptive transfer of splenic DN cells gives rise to CD8αα cells in the gut, establishing their precursor relationship in vivo. Interestingly, Bim does not restrict the IL-15-driven maturation of CD8αα cells that is critical for intestinal homeostasis. Thus, we found a temporal and tissue-specific role for Bim in limiting thymic agonist selection of CD8αα precursors and their TCRß repertoire, but not in the maintenance of CD8αα intraepithelial lymphocytes in the intestine.

DMFC (3,5-dimethyl-7H-furo[3,2-g]chromen-7-one) regulates Bim to trigger Bax and Bak activation to suppress drug-resistant human hepatoma.

3,5-Dimethyl-7H-furo[3,2-g]chromen-7-one (DMFC) is a coumarin derivative with anti-cancer activity against human hepatoma cells, but the mechanisms underlying DMFC function in cancer suppression is unknown. In this study, we aimed at elucidating the molecular mechanisms underlying DMFC anti-cancer activity and determining whether DMFC is effective in suppression of drug-resistant human hepatocellular carcinoma. We show here that DMFC effectively suppresses both the parent and the multidrug-resistant hepatoma cell growth in vitro and DMFC suppresses hepatoma cell growth at least in part through inducing tumor cell apoptosis. In the molecular level, we observed that DMFC treatment decreases Bcl-2 level by a post-transcriptional mechanism and activates Bim transcription to increase Bim mRNA and protein level in hepatoma cells. Furthermore, co-immunoprecipitation studies revealed that DMFC-induced Bim interrupts interactions between Bcl-2 and Bax and between Mcl-1 and Bak, resulting in dissociation of Bax from Bcl-2 and Bak from Mcl-1 and subsequent activation of both Bax and Bak. Activation of Bax and Bak leads to mitochondrial outer membrane permeabilization and cytochrome c release. Consistent with its potent apoptosis-inducing activity, DMFC exhibited potent activity against the multidrug-resistant hepatoma xenograft growth in vivo. Therefore, we determine that DMFC suppresses hepatoma growth through decreasing Bcl-2 and increasing Bim to induce tumor cell apoptosis and hold great promise for further development as a therapeutic agent to treat chemoresistant hepatoma.

Association of BIM Deletion Polymorphism and BIM-γ RNA Expression in NSCLC with EGFR Mutation.

AIM: This pilot study assessed the association of BIM deletion polymorphism and BIM RNA isoform in patients with EGFR-positive non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: The study included 33 patients with EGFR-positive NSCLC treated with gefitinib. BIM deletion polymorphism and BIM RNA isoform (EL/L/S/γ) were determined by polymerase chain reaction (PCR). RESULTS: BIM-γ expression was significantly higher in patients with BIM deletion polymorphism than among those without BIM deletion polymorphism inside tumors (p=0.038) and around tumors (p=0.0024). Relative BIM-γ expression was significantly higher in patients with BIM deletion polymorphism than among those without BIM deletion polymorphism (p=0.0017). Patients with BIM-γ had significantly shorter progression-free survival than those without BIM-γ (median: 304 vs. 732 days; p=0.023). CONCLUSION: Expression of BIM-γ mRNA and BIM deletion polymorphism were strongly associated. BIM-γ overexpression may have a role in apoptosis related to EGFR-tyrosine kinase inhibitor.

The long non-coding RNA Morrbid regulates Bim and short-lived myeloid cell lifespan.

Neutrophils, eosinophils and 'classical' monocytes collectively account for about 70% of human blood leukocytes and are among the shortest-lived cells in the body. Precise regulation of the lifespan of these myeloid cells is critical to maintain protective immune responses and minimize the deleterious consequences of prolonged inflammation. However, how the lifespan of these cells is strictly controlled remains largely unknown. Here we identify a long non-coding RNA that we termed Morrbid, which tightly controls the survival of neutrophils, eosinophils and classical monocytes in response to pro-survival cytokines in mice. To control the lifespan of these cells, Morrbid regulates the transcription of the neighbouring pro-apoptotic gene, Bcl2l11 (also known as Bim), by promoting the enrichment of the PRC2 complex at the Bcl2l11 promoter to maintain this gene in a poised state. Notably, Morrbid regulates this process in cis, enabling allele-specific control of Bcl2l11 transcription. Thus, in these highly inflammatory cells, changes in Morrbid levels provide a locus-specific regulatory mechanism that allows rapid control of apoptosis in response to extracellular pro-survival signals. As MORRBID is present in humans and dysregulated in individuals with hypereosinophilic syndrome, this long non-coding RNA may represent a potential therapeutic target for inflammatory disorders characterized by aberrant short-lived myeloid cell lifespan.

Ruxolitinib synergizes with DMF to kill via BIM+BAD-induced mitochondrial dysfunction and via reduced SOD2/TRX expression and ROS.

We determined whether the myelofibrosis drug ruxolitinib, an inhibitor of Janus kinases 1/2 (JAK1 and JAK2), could interact with the multiple sclerosis drug dimethyl-fumarate (DMF) to kill tumor cells; studies used the in vivo active form of the drug, mono-methyl fumarate (MMF). Ruxolitinib interacted with MMF to kill brain, breast, lung and ovarian cancer cells, and enhanced the lethality of standard of care therapies such as paclitaxel and temozolomide. MMF also interacted with other FDA approved drugs to kill tumor cells including Celebrex® and Gilenya®. The combination of [ruxolitinib + MMF] inactivated ERK1/2, AKT, STAT3 and STAT5; reduced expression of MCL-1, BCL-XL, SOD2 and TRX; increased BIM expression; decreased BAD S112 S136 phosphorylation; and enhanced pro-caspase 3 cleavage. Expression of activated forms of STAT3, MEK1 or AKT each significantly reduced drug combination lethality; prevented BAD S112 S136 dephosphorylation and decreased BIM expression; and preserved TRX, SOD2, MCL-1 and BCL-XL expression. The drug combination increased the levels of reactive oxygen species in cells, and over-expression of TRX or SOD2 prevented drug combination tumor cell killing. Over-expression of BCL-XL or knock down of BAX, BIM, BAD or apoptosis inducing factor (AIF) protected tumor cells. The drug combination increased AIF : HSP70 co-localization in the cytosol but this event did not prevent AIF : eIF3A association in the nucleus.

MicroRNA-138 promotes acquired alkylator resistance in glioblastoma by targeting the Bcl-2-interacting mediator BIM.

Glioblastoma is the most aggressive brain tumor in adults with a median survival below 12 months in population-based studies. The main reason for tumor recurrence and progression is constitutive or acquired resistance to the standard of care of surgical resection followed by radiotherapy with concomitant and adjuvant temozolomide (TMZ/RT→TMZ). Here, we investigated the role of microRNA (miRNA) alterations as mediators of alkylator resistance in glioblastoma cells. Using microarray-based miRNA expression profiling of parental and TMZ-resistant cultures of three human glioma cell lines, we identified a set of differentially expressed miRNA candidates. From these, we selected miR-138 for further functional analyses as this miRNA was not only upregulated in TMZ-resistant versus parental cells, but also showed increased expression in vivo in recurrent glioblastoma tissue samples after TMZ/RT→TMZ treatment. Transient transfection of miR-138 mimics in glioma cells with low basal miR-138 expression increased glioma cell proliferation. Moreover, miR-138 overexpression increased TMZ resistance in long-term glioblastoma cell lines and glioma initiating cell cultures. The apoptosis regulator BIM was identified as a direct target of miR-138, and its silencing mediated the induced TMZ resistance phenotype. Altered sensitivity to apoptosis played only a minor role in this resistance mechanism. Instead, we identified the induction of autophagy to be regulated downstream of the miR-138/BIM axis and to promote cell survival following TMZ exposure. Our data thus define miR-138 as a glioblastoma cell survival-promoting miRNA associated with resistance to TMZ therapy in vitro and with tumor progression in vivo.

Mitotic cell death caused by follistatin-like 1 inhibition is associated with up-regulated Bim by inactivated Erk1/2 in human lung cancer cells.

Follistatin-like 1 (FSTL1) was identified as a novel pro-inflammatory protein showing high-level expression in rheumatoid arthritis. The protective effect of FSTL1 via the inhibition of apoptosis was reported in myocardial injury. However, the functional mechanism of FSTL1 in cancer is poorly characterized, and its proliferative effects are ambiguous. Here, we examined the effects of FSTL1 on cellular proliferation and cell cycle checkpoints in lung cancer cells. FSTL1 inhibition induced the cellular portion of G2/M phase in human lung cancer cells via the accumulation of regulators of the transition through the G2/M phase, including the cyclin-dependent kinase 1 (Cdk1)-cyclin B1 complex. An increase in histone H3 phosphorylation (at Ser10), another hallmark of mitosis, indicated that the knockdown of FSTL1 in lung cancer cells stimulated a mitotic arrest. After that, apoptosis was promoted by the activation of caspase-3 and -9. Protein level of Bim, a BH3 domain-only, pro-apoptotic member and its isoforms, BimL, BimS, and BimEL were up-regulated by FSTL1 inhibition. Degradation of Bim was blocked in FSTL1-knockdown cells by decreased phosphorylation of Bim. Increased BimEL as well as decreased phosphorylated Erk1/2 is essential for cell death by FSTL1 inhibition in NCI-H460 cells. Taken together, our results suggest that the knockdown of FSTL1 induces apoptosis through a mitotic arrest and caspase-dependent cell death. FSTL1 plays the important roles in cellular proliferation and apoptosis in lung cancer cells, and thus can be a new target for lung cancer treatment.