Osteopontin b and c isoforms: Molecular Candidates Associated with Leukemic Stem Cell Chemoresistance in Acute Myeloid Leukemia

Quercetin can be a more reliable treatment for metastatic prostate cancer than the localized disease: An in vitro study

Quercetin is a plant flavonoid that has been recognized to have anti-inflammatory, antioxidant and anti-proliferative activities. This study aims to evaluate the inhibitory effects of quercetin against prostate malignancy in vitro and the underlying resistance mechanism. IC50 values of quercetin were determined by MTT assay. Annexin-V/PI staining was used to measure the rate of apoptosis. DNA cell cycle was analysed by PI staining method. Real-time PCR was performed to assess mRNA levels of OPN isoforms, VEGF isoforms, P53 and KLK2. Migration potential, proliferative capability and nucleus morphology of cells were evaluated by the scratch-wound assay, colony-forming assay and Hoechst staining, respectively. Quercetin significantly increased the apoptosis rate of PC-3 and LNCaP cell lines, arrested the cell cycle at the sub-G1/G1 phase, and reduced the migration potential and colony-forming capability. Moreover, upregulation of apoptosis-related genes and downregulation of genes involved in proliferation and angiogenesis was also observed. Although our results elucidated that quercetin has antitumor effects on PC-3 and LNCaP, for the first time, we showed that quercetin treatment causes alterations in the expression of OPN and VEGF isoforms, which are cancer-promoting modulators through various processes such as angiogenesis and drug-resistance. Prostate malignant cells can dodge the anti-carcinogenic properties of quercetin via modulation of OPN and VEGF isoforms in vitro. Therefore, quercetin acts as a double-edged sword in prostate cancer treatment.

Integrated Transcriptomic Analysis Revealed Hub Genes and Pathways Involved in Sorafenib Resistance in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), a high mortality malignancy, has become a worldwide public health concern. Acquired resistance to the multikinase inhibitor sorafenib challenges its clinical efficacy and the survival benefits it provides to patients with advanced HCC. This study aimed to identify critical genes and pathways associated with sorafenib resistance in HCC using integrated bioinformatics analysis. Differentially expressed genes (DEGs) were identified using four HCC gene expression profiles (including 34 sorafenib-resistant and 29 sorafenib-sensitive samples) based on the robust rank aggregation method and R software. Gene ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed using the Database for Annotation, Visualization and Integrated Discovery (DAVID) online tool. A protein–protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes (STRING), and small molecules reversing sorafenib resistance were searched for using the connectivity map (CMAP) database. Pearson correlation and survival analyses of hub genes were performed using cBioPortal and Gene Expression Profiling and Interactive Analysis (GEPIA). Finally, the expression levels of hub genes in sorafenib-resistant HCC cells were verified using quantitative polymerase chain reaction (q-PCR). A total of 165 integrated DEGs (66 upregulated and 99 downregulated in sorafenib resistant samples compared sorafenib sensitive ones) primarily enriched in negative regulation of endopeptidase activity, extracellular exosome, and protease binding were identified. Some pathways were commonly shared between the integrated DEGs. Seven promising therapeutic agents and 13 hub genes were identified. These findings provide a strategy and theoretical basis for overcoming sorafenib resistance in HCC patients.

Investigation of the Osteopontin isoforms expression in patients with acute myeloid leukemia

Acute myeloid leukemia (AML) is one of the major hematological malignancies. Advances in molecular research have greatly improved our understanding of the process of leukemia formation in AML. Osteopontin (OPN) is a novel molecule that mediates critical processes for cancer progression. The aim of this study was to investigate the relative expression of OPN gene isoforms in AML patients on days 0, 14, and 28 after chemotherapy. The bone marrow samples were collected from 40 newly diagnosed AML patients (24 male and 16 female with a mean age of 30 years) at the initial time of diagnosis, 14 and 28 days after treatment. The peripheral blood samples of 10 healthy individuals were also collected as the control group. The expression of OPN isoforms was investigated by Real-Time Quantitative PCR. The expression of VEGFc/STAT3/CXCR4 was also investigated by Real-Time PCR. Findings indicated that OPNb and OPNc isoforms had significantly overexpression in AML patients on 14 and 28 days after treatment compared to normal samples (P < 0.05). The level of OPNb and OPNc isoforms was increased significantly in M0, M1, and M2 subgroups with overexpression of VEGFc/STAT3/CXCR4, 28 days after starting chemotherapy (P < 0.05). Our results suggested that OPNb and OPNc isoforms play a major role in cancer relapse. Therefore, they can be used as a valuable prognostic and diagnostic biomarker for relapse of the AML disease. However, these findings need confirmation with further studies.

MiR-139 Modulates Cancer Stem Cell Function of Human Breast Cancer through Targeting CXCR4

Elevated expression of C-X-C motif chemokine receptor 4 (CXCR4) correlates with chemotaxis, invasion, and cancer stem cell (CSC) properties within several solid-tumor malignancies. Recent studies reported that microRNA (miRNA) modulates the stemness of embryonic stem cells. We aimed to investigate the role of miRNA, via CXCR4-modulation, on CSC properties in breast cancer using cell lines and xenotransplantation mouse model and evaluated miR-193 levels in 191 patients with invasive ductal carcinoma. We validated miR-139 directly targets the 3'-untranslated region of CXCR4. Hoechst 33342 fluorescence-activated cell sorting (FACS) and sphere-forming assay were used to identify CSCs. MiR-139 suppressed breast CSCs with mesenchymal traits; led to decreased migration and invasion abilities through down-regulating CXCR4/p-Akt signaling. In lung cancer xenograft model of nude mice transplanted with human miR-139-carrying MDA-MB-231 cells, metastatic lung nodules were suppressed. Clinically, microdissected breast tumor tissues showed miR-139 reduction, compared to adjacent non-tumor tissues, that was significantly associated with worse clinicopathological features, including larger tumor size, advanced tumor stage and lymph node metastasis; moreover, reduced miR-139 level was predominately occurred in late-stage HER2-oreexpression tumors. Collectively, our findings highlight miR-139-mediated suppression of CXCR4/p-Akt signaling and thereby affected mesenchymal stem-cell genesis, indicating its potential as a therapeutic target for invasive breast cancer.

STAT3, the Challenge for Chemotherapeutic and Radiotherapeutic Efficacy

Chemoradiotherapy is one of the most effective and extensively used strategies for cancer treatment. Signal transducer and activator of transcription 3 (STAT3) regulates vital biological processes, such as cell proliferation and cell growth. It is constitutively activated in various cancers and limits the application of chemoradiotherapy. Accumulating evidence suggests that STAT3 regulates resistance to chemotherapy and radiotherapy and thereby impairs therapeutic efficacy by mediating its feedback loop and several target genes. The alternative splicing product STAT3β is often identified as a dominant-negative regulator, but it enhances sensitivity to chemotherapy and offers a new and challenging approach to reverse therapeutic resistance. We focus here on exploring the role of STAT3 in resistance to receptor tyrosine kinase (RTK) inhibitors and radiotherapy, outlining the potential of targeting STAT3 to overcome chemo(radio)resistance for improving clinical outcomes, and evaluating the importance of STAT3β as a potential therapeutic approach to overcomes chemo(radio)resistance. In this review, we discuss some new insights into the effect of STAT3 and its subtype STAT3β on chemoradiotherapy sensitivity, and we explore how these insights influence clinical treatment and drug development for cancer.

Adhesion Deregulation in Acute Myeloid Leukaemia

Cell adhesion is a process through which cells interact with and attach to neighboring cells or matrix using specialized surface cell adhesion molecules (AMs). Adhesion plays an important role in normal haematopoiesis and in acute myeloid leukaemia (AML). AML blasts express many of the AMs identified on normal haematopoietic precursors. Differential expression of AMs between normal haematopoietic cells and leukaemic blasts has been documented to a variable extent, likely reflecting the heterogeneity of the disease. AMs govern a variety of processes within the bone marrow (BM), such as migration, homing, and quiescence. AML blasts home to the BM, as the AM-mediated interaction with the niche protects them from chemotherapeutic agents. On the contrary, they detach from the niches and move from the BM into the peripheral blood to colonize other sites, i.e., the spleen and liver, possibly in a process that is reminiscent of epithelial-to-mesenchymal-transition in metastatic solid cancers. The expression of AMs has a prognostic impact and there are ongoing efforts to therapeutically target adhesion in the fight against leukaemia.

Osteopontin b and c Splice isoforms in Leukemias and Solid Tumors: Angiogenesis Alongside Chemoresistance

Osteopontin (OPN) is a glycoprotein involved in regulation of various influences on tumor progression, such as cellular proliferation, apoptosis, angiogenesis, and metastasis. Vascular endothelial growth factor (VEGF) is a secreted molecule supporting angiogenesis in various cancers through activation of the PI3K/AKT/ERK1/2 pathway. OPN and VEGF have a number of isoforms with various activities. In spite of the well-defined association between OPN and VEGF isoform expression and cure rate for solid tumors, there is a scarcity of information as to any association in leukemia. Based on the critical role of OPN in cell survival, it seems reasonable to hypothesize that OPN and VEGF isoform expression levels may impact on chemoresistance and relapse in leukemia the same as in solid tumors. Hence, the aim of our review was to explain relationships between OPN and VEGF isoforms and angiogenesis and related pathways in chemoresistance of leukemia and solid tumors. Our findings demonstrated that OPNb and OPNc alongside with VEGF isoforms and other gene pathways are involved in angiogenesis and also might promote chemoresistance and even recurrence in leukemia and solid tumors. To sum up, targeting OPN isoforms, particularly b and c, might be a novel therapeutic strategy for the treatment of leukemia as well as solid tumors.

Anti-Vascular Endothelial Growth Factor Targeting by Curcumin and Thalidomide in Acute Myeloid Leukemia Cells

Acute myeloid leukemias (AMLs) are blood disorders that exhibit uncontrolled growth and reduction of apoptosis rates. As with other malignancies, progression may be result of induction and formation of new blood vessels influenced by disease conditions. Cancer cells produce a variety of factors which play important roles in angiogenesis. Vascular endothelial growth factor (VEGF) is critical for many malignancies, including AMLs. Curcumin, as a natural compound, is able to enhance apoptosis via a mechanism affecting regulatory genes. As a new strategy we here evaluated anti-VEGF properties of curcumin, alone and in combination with thalidomide, in leukemic cell lines. Growth inhibitory effects were assessed by MTT assay and apoptosis was detected by annexin/PI staining in U937 and KG-1 cell lines. mRNA expression levels of VEGF isoforms were evaluated by qRT-PCR. Curcumin inhibited proliferation and induced apoptosis in both KG-1 and U937 cells and this effect was stronger in combination with thalidomide. In KG-1 cells, the level of VEGF (A, B, C and D) mRNA was decreased in curcumin-treated as compared to untreated cells. Maximum effects were obtained at the concentration of 40 μM curcumin in U937 cells. Taken together, the results indicate that the VEGF autocrine loop may have an impact on AML development and progression and could be considered as a therapeutic target. Thalidomide as a VEGF inhibitor in combination with curcumin appears to have a synergistic impact on inhibition of cell proliferation and promotion of apoptosis.

OPN b and c Isoforms Doubtless Veto Anti-angiogenesis Effects of Curcumin in Combination with Conventional AML Regiment

Osteopontin (OPN) is an extracellular structural protein that is secreted by osteoblasts and hematopoietic cells. It suppresses the proliferation of hematopoietic stem and also plays an important role in promoting survival and drug resistance in leukemic stem cells (LSCs). Since the role of OPN isoforms in AML angiogenesis are remaining controversial, in the present study, we aimed to evaluate whether curcumin (CUR), as a known natural component with anti-angiogenesis effects, in a combination of AML conventional regiment has the potency to preclude induced anti-angiogenesis effects of OPN isoforms or not? Leukemia cells were treated with different concentration of CUR and AML conventional drugs alone and/or in combination with together to find effective doses and IC50 values. Percentages of apoptotic cells were evaluated by Annexin/PI staining and mRNA levels of OPN isoforms and AKT/ VEGF-A and VEGF-C/ STAT3/ β-catenin/ CXCR4/ IL-6/ KDR gene expression were investigated by Real Time-PCR method. Moreover, to confirm OPN gene expression data, we investigated the effect of simvastatin and OPN siRNA as an OPN inhibitor on the cell proliferation and induction of apoptosis in the indicated cell lines. Our data display that Ara-c (2μM and 1μM in KG-1 and U937 cell lines respectively), CUR (40μM in both cell lines), and also their combination significantly increased the percentage of apoptotic cells. Moreover, the mRNA level of OPN isoforms were down regulated in the KG-1and U937 cell lines treated with Ara-c while, upregulated in KG-1and U937 cell lines treated with CUR and its combination. Our results suggest that despite anti-angiogenesis effects of CUR, AML cells probably evade from anti-angiogenesis effects of CUR via induction of OPN b and c isoform and related molecular pathways.