Overexpression of Lhx2 suppresses proliferation of human T cell acute lymphoblastic leukemia-derived cells, partly by reducing LMO2 protein levels

ERN1 knockdown modifies the hypoxic regulation of homeobox gene expression in U87MG glioblastoma cells

OBJECTIVE.

Homeobox genes play an important role in health and disease including oncogenesis. The present investigation aimed to study ERN1-dependent hypoxic regulation of the expression of genes encoding homeobox proteins MEIS (zinc finger E-box binding homeobox 2) and LIM homeobox 1 family, SPAG4 (sperm associated antigen 4) and NKX3-1 (NK3 homeobox 1) in U87MG glioblastoma cells in response to inhibition of ERN1 (endoplasmic reticulum to nucleus signaling 1) for evaluation of their possible significance in the control of glioblastoma growth.

METHODS.

The expression level of homeobox genes was studied in control (transfected by vector) and ERN1 knockdown U87MG glioblastoma cells under hypoxia induced by dimethyloxalylglycine (0.5 mM for 4 h) by quantitative polymerase chain reaction and normalized to ACTB.

RESULTS.

It was found that hypoxia down-regulated the expression level of LHX2, LHX6, MEIS2, and NKX3-1 genes but up-regulated the expression level of MEIS1, LHX1, MEIS3, and SPAG4 genes in control glioblastoma cells. At the same time, ERN1 knockdown of glioblastoma cells significantly modified the sensitivity of all studied genes to a hypoxic condition. Thus, ERN1 knockdown of glioblastoma cells removed the effect of hypoxia on the expression of MEIS1 and LHX1 genes, but increased the sensitivity of MEIS2, LHX2, and LHX6 genes to hypoxia. However, the expression of MEIS3, NKX3-1, and SPAG4 genes had decreased sensitivity to hypoxia in ERN1 knockdown glioblastoma cells. Moreover, more pronounced changes under the conditions of ERN1 inhibition were detected for the pro-oncogenic gene SPAG4.

CONCLUSION.

The results of the present study demonstrate that hypoxia affected the expression of homeobox genes MEIS1, MEIS2, MEIS3, LHX1, LHX2, LHX6, SPAG4, and NKX3-1 in U87MG glioblastoma cells in gene-specific manner and that the sensitivity of all studied genes to hypoxia condition is mediated by ERN1, the major pathway of the endoplasmic reticulum stress signaling, and possibly contributed to the control of glioblastoma growth. A fundamentally new results of this work is the establishment of the fact regarding the dependence of hypoxic regulation of SPAG4 gene expression on ER stress, in particular ERN1, which is associated with suppression of cell proliferation and tumor growth.

Identification of compounds that preferentially suppress the growth of T-cell acute lymphoblastic leukemia-derived cells

T-cell acute lymphoblastic leukemia (T-ALL) is one of the most frequently occurring cancers in children and is associated with a poor prognosis. Here, we performed large-scale screening of natural compound libraries to identify potential drugs against T-ALL. We identified three low-molecular-weight compounds (auxarconjugatin-B, rumbrin, and lavendamycin) that inhibited the proliferation of the T-ALL cell line CCRF-CEM, but not that of the B lymphoma cell line Raji in a low concentration range. Among them, auxarconjugatin-B and rumbrin commonly contained a polyenyl 3-chloropyrrol in their chemical structure, therefore we chose auxarconjugatin-B for further analyses. Auxarconjugatin-B suppressed the in vitro growth of five human T-ALL cell lines and two T-ALL patient-derived cells, but not that of adult T-cell leukemia patient-derived cells. Cultured normal T cells were several-fold resistant to auxarconjugatin-B. Auxarconjugatin-B and its synthetic analogue Ra#37 depolarized the mitochondrial membrane potential of CCRF-CEM cells within 3 h of treatment. These compounds are promising seeds for developing novel anti-T-ALL drugs.

miR-495-3p sensitizes BCR-ABL1-expressing leukemic cells to tyrosine kinase inhibitors by targeting multidrug resistance 1 gene in T315I mutated cells

Chronic myeloid leukemia (CML) is a clonal hematopoietic malignancy driven by the BCR-ABL1 fusion oncoprotein. The development of tyrosine kinase inhibitors (TKIs) has deeply increased long-term survival of CML patients. Nonetheless, one patient out of four will switch TKI off owing either to drug intolerance or resistance partly due to amplification or mutations of BCR-ABL1 oncogene and alteration in ATP-binding cassette (ABC) transporters. Increasing evidence suggests the involvement of the microRNA miR-495-3p in cancer-associated chemoresistance through multidrug resistance 1 (MDR1) gene, which encodes an ATP-dependent efflux pump. Our study aimed at investigating the potential role of miR-495-3p in CML TKI chemo-sensitivity and determining the underlying molecular circuitry involved. We first observed that miR-495-3p expression was lower in BCR-ABL1-expressing cellular models in vitro. Notably, loss-of-function experiments showed increased proliferation associated with a decreased number of nondividing cells (G0/G1) and resistance to Imatinib. Conversely, our data showed that miR-495-3p overexpression hindered leukemic cell growth and TKI resistance in Imatinib-resistant T315I-mutant cells, as well as drug efflux activity through MDR1 regulation. Further investigating the role of miR-495-3p in CML patients, we found that predicted miR-495-3p targets were upregulated in patients in blast crisis that were involved in protein phosphorylation and associated with the worst prognosis. Taken together, our results demonstrate that downregulation of miR-495-3p expression is important in the malignant phenotype of CML and TKI resistance mechanisms and could be a useful biomarker and a potential therapeutic target to eradicate CML.

Identification of prognostic indicators, diagnostic markers, and possible therapeutic targets among LIM homeobox transcription factors in breast cancer

Background

Breast cancer (BRCA) is the most common malignant tumor among women worldwide. Despite advances in treatment, many patients still die from a lack of effective diagnostic and prognostic markers and powerful therapeutic targets. LIM homeobox genes (LHXs) play vital roles in regulating the development of various organisms. However, there are limited reports regarding their roles in the diagnosis, prognosis, and treatment of BRCA.

Methods

UALCAN, Kaplan-Meier plotter, cBioPortal, GeneMANIA, STRING, DAVID 6.8, TRRUST v2, LinkedOmics, and TIMER were utilized to analyze differential expression, prognostic value, genetic alteration, neighbor gene network, transcription factor targets, kinase targets, and immune cell infiltration of LHXs in BRCA patients.

Results

LHX gene expression patterns are clear in BRCA and its different subtypes. Further analyses indicated that this altered expression is possibly affected by genetic and/or epigenetic changes. The prognostic and diagnostic values of certain LHXs are unique to different BRCA subtypes. LHXs are mainly involved in the regulation of differentiation and development, and their neighbor genes are primarily involved in cancer-related pathways. Moreover, most LHXs are closely correlated with immune cell infiltration. Furthermore, LHXs may exert their functions by regulating a series of transcription factor and kinase targets.

Conclusions

LHXs are unique diagnostic and prognostic markers and participate in cancer through different signaling pathways and/or regulatory mechanisms in BRCA. This study provides potential applications of LHXs for the diagnosis, prognosis, and treatment of BRCA and its different subtypes.

The impact of glutamine deprivation on the expression of MEIS3, SPAG4, LHX1, LHX2, and LHX6 genes in ERN1 knockdown U87 glioma cells

Objective. The aim of the current study was to investigate the expression of genes encoded homeobox proteins such as MEIS3 (Meis homeobox 3), SPAG4 (sperm associated antigen 4), LHX1 (LIM homeobox 1), LHX2, and LHX6 in U87 glioma cells in response to glutamine deprivation in control glioma cells and cells with knockdown of ERN1 (endoplasmic reticulum to nucleus signaling 1), the major pathway of the endoplasmic reticulum stress signaling, for evaluation of a possible dependence on the expression of these important regulatory genes from glutamine supply and ERN1 signaling. Methods. The expression level of MEIS3, SPAG4, LHX, LHX2, and LHX6 genes was studied by real-time quantitative polymerase chain reaction in control U87 glioma cells (transfected by vector) and cells with ERN1 knockdown after exposure to glutamine deprivation. Results. It was shown that the expression level of MEIS3 and LHX1 genes was up-regulated in control glioma cells treated by glutamine deprivation. At the same time, the expression level of three other genes (LHX2, LHX6, and SPAG4) was down-regulated. Furthermore, ERN1 knockdown significantly modified the effect of glutamine deprivation on LHX1 gene expression in glioma cells, but did not change significantly the sensitivity of all other genes expression to this experimental condition. Conclusion. The results of this investigation demonstrate that the exposure of U87 glioma cells under glutamine deprivation significantly affected the expression of all genes studied encoding the homeobox proteins and that this effect of glutamine deprivation was independent of the endoplasmic reticulum stress signaling mediated by ERN1, except LHX1 gene.

LIM Homeobox-2 Suppresses Hallmarks of Adult and Pediatric Liver Cancers by Inactivating MAPK/ERK and Wnt/Beta-Catenin Pathways

INTRODUCTION

Hepatocellular carcinoma and hepatoblastoma are two liver cancers characterized by gene deregulations, chromosomal rearrangements, and mutations in Wnt/beta-catenin (Wnt) pathway-related genes. LHX2, a transcriptional factor member of the LIM homeobox gene family, has important functions in embryogenesis and liver development. LHX2 is oncogenic in many solid tumors and leukemia, but its role in liver cancer is unknown.

METHODS

We analyzed the expression of LHX2 in hepatocellular carcinoma and hepatoblastoma samples using various transcriptomic datasets and biological samples. The role of LHX2 was studied using lentiviral transduction, in vitro cell-based assays (growth, migration, senescence, and apoptosis), molecular approaches (phosphokinase arrays and RNA-seq), bioinformatics, and two in vivo models in chicken and Xenopus embryos.

RESULTS

We found a strong connection between LHX2 downregulation and Wnt activation in these two liver cancers. In hepatoblastoma, LHX2 downregulation correlated with multiple poor outcome parameters including higher patient age, intermediate- and high-risk tumors, and low patient survival. Forced expression of LHX2 reduced the proliferation, migration, and survival of liver cancer cells in vitro through the inactivation of MAPK/ERK and Wnt signals. In vivo, LHX2 impeded the development of tumors in chick embryos and repressed the Wnt pathway in Xenopus embryos. RNA-sequencing data and bioinformatic analyses confirmed the deregulation of many biological functions and molecular processes associated with cell migration, cell survival, and liver carcinogenesis in LHX2-expressing hepatoma cells. At a mechanistic level, LHX2 mediated the disassembling of beta-catenin/T-cell factor 4 complex and induced expression of multiple inhibitors of Wnt (e.g., TLE/Groucho) and MAPK/ERK (e.g., DUSPs) pathways.

CONCLUSION

Collectively, our findings demonstrate a tumor suppressive function of LHX2 in adult and pediatric liver cancers.

ERN1 knockdown modifies the effect of glucose deprivation on homeobox gene expressions in U87 glioma cells

OBJECTIVE

The aim of the present investigation was to study the expression of genes encoding homeobox proteins ZEB2 (zinc finger E-box binding homeobox 2), TGIF1 (TGFB induced factor homeobox 1), SPAG4 (sperm associated antigen 4), LHX1 (LIM homeobox 1), LHX2, LHX6, NKX3-1 (NK3 homeobox 1), and PRRX1 (paired related homeobox 1) in U87 glioma cells in response to glucose deprivation in control glioma cells and cells with knockdown of ERN1 (endoplasmic reticulum to nucleus signaling 1), the major pathway of the endoplasmic reticulum stress signaling, for evaluation of it possible significance in the control of glioma growth through ERN1 signaling and chemoresistance.

METHODS

The expression level of homeobox family genes was studied in control (transfected by vector) and ERN1 knockdown U87 glioma cells under glucose deprivation condition by real-time quantitative polymerase chain reaction.

RESULTS

It was shown that the expression level of ZEB2, TGIF1, PRRX1, and LHX6 genes was up-regulated in control glioma cells treated by glucose deprivation. At the same time, the expression level of three other genes (NKX3-1, LHX1, and LHX2) was down-regulated. Furthermore, ERN1 knockdown of glioma cells significantly modified the effect glucose deprivation condition on the expression almost all studied genes. Thus, treatment of glioma cells without ERN1 enzymatic activity by glucose deprivation condition lead to down-regulation of the expression level of ZEB2 and SPAG4 as well as to more significant up-regulation of PRRX1 and TGIF1 genes. Moreover, the expression of LHX6 and NKX3-1 genes lost their sensitivity to glucose deprivation but LHX1 and LHX2 genes did not change it significantly.

CONCLUSIONS

The results of this investigation demonstrate that ERN1 knockdown significantly modifies the sensitivity of most studied homeobox gene expressions to glucose deprivation condition and that these changes are a result of complex interaction of variable endoplasmic reticulum stress related and unrelated regulatory factors and contributed to glioma cell growth and possibly to their chemoresistance.

Synthesis of polyenylpyrrole derivatives with selective growth inhibitory activity against T-cell acute lymphoblastic leukemia cells

T-cell acute lymphoblastic leukemia (T-ALL) is a hardly curable disease with a high relapse rate. 20 analogs were synthesized based on the structures of two kinds of fungi-derived polyenylpyrrole products (rumbrin (1) and auxarconjugatin-B (2)) to suppress the growth of T-ALL-derived cell line CCRF-CEM and tested for growth-inhibiting activity. The octatetraenylpyrrole analog gave an IC₅₀ of 0.27 μM in CCRF-CEM cells, while it did not affect Burkitt lymphoma-derived cell line Raji and the cervical cancer cell line HeLa, or the oral cancer cell line HSC-3 (IC₅₀ > 10 μM). This compound will be a promising compound for developing T-ALL-specific drugs.