Applications of Aptamers in Cancer Therapy

Aptamers are small and specific oligonucleotides [RNA or single-strand DNA (ssDNA)] with a high binding affinity against target protein. In vitro selection process of aptamer by selective evolution of ligands by exponential enrichment (SELEX) has been invented in 1990 by Larry Gold and Jack Szostak. SELEX is a random amplification of target protein with combined oligonucleotide libraries and selection of synthesized aptamer by magnetic beads, affinity chromatography, and capillary electrophoresis-based methods. According to their low molecular weight, non-immunogenic feature in vivo, low production cost, high thermal stability, increase in production potential, and ample of modification capacities, aptamers are becoming essential medical tools for diagnosis and treatment of diseases such as macular degeneration, hemophilia, heart disease, and various cancer types. The therapeutic potential of aptamers, with high binding affinity against carcinogenesis-associated growth factors, receptors, or proteins frequently overexpressed in specific cancers such as prostate, breast, colon, lung, leukemia, hepatocellular, and cervical carcinoma. The strategies for aptamer-based drugs in cancer therapy design/modify aptamers against cancer biomarkers, accelerate immunotherapy targeting immune system, and increase the drug delivery in cancer cells. In conclusion, aptamers are promising candidate drugs due to their antiproliferative effect on cancer cells and the drug delivery systems during cancer chemotherapy

Aging-Related Diseases and Autophagy

Autophagy is fundamental, evolutionary conserved physiological process at molecular level which targets long-lived cytosolic proteins and organelles to be recycled through lysosomal degradation. Diminished autophagic activity caused cellular stress in many organisms following aging, and inhibition of autophagy in model organisms causes degenerative changes and pathologic diseases observed with high incidence ratio generally in older ages. Consequently the delayed senescence or increased longevity in model organisms often stimulate autophagy, and autophagy inhibition compromises anti-aging effects. The cytoprotective function of autophagy is presented in various human diseases such as lung, liver, cardiovascular diseases, neurodegeneration, myopathies, cancer, stroke, infections and metabolic diseases which are found associated with autophagic targets. These pathologies are defined with their age-dependent characteristics, is not fully understood that how autophagy network regulates metabolism and may cause diseases in age-related manner. In this book chapter, we are going to discuss the autophagy and aging relationship in three different parts. In the first section autophagy and aging relationship is going to be presented through explaining responsible signalling network. The autophagy and age-related neurological disorders, genetic basis of age-dependent diseases and the functional role of autophagy is going to be discussed in the second and third part of the chapter

Breast Cancer and Flavonoids as Treatment Strategy

Breast cancer is the most prevalent cancer type among women. Despite recent progress in early detection and therapeutic strategies, the rate of mortality is increasing. Anti-estrogens or aromatase inhibitors are preferred to treat the women diagnosed with estrogen-receptor (ER) positive tumors. However, breast tumors usually show intra-tumoral heterogeneity with ER-positive and -negative cells. The advanced breast cancer cells lose the estrogen responsiveness and become aggressive by developing new strategies for rapid proliferation such as mutations in cell cycle machinery. New promising drugs are still being investigating against these types of tumors especially to overcome acquired resistance against chemotherapeutic drugs; however, a successful treatment for metastatic tumors is still unclear. Flavonoids, with various pharmacological activities, are plant or fungus secondary metabolites present in human diet. In plants, beside their role in pigmentation, they may also act as messengers, regulators and cell cycle inhibitors. Therefore, they are being tested in ovarian, cervical as well as breast cancer. Due to the positive correlation between flavonoids-rich diet and lower risk of cancer, flavonoids are referred as chemopreventive agents. The current chapter emphasizes the therapeutic potential of flavonoids and their synthetic analogues as anti-cancer agents in breast cancer providing new insights into the molecular mechanisms

In Vitro Investigations of miR-33a Expression in Estrogen Receptor-Targeting Therapies in Breast Cancer Cells

Background: Increased fatty acid synthesis leads to the aggressive phenotype of breast cancer and renders efficiency of therapeutics. Regulatory microRNAs (miRNAs) on lipid biosynthesis pathways as miR-33a have potential to clarify the exact mechanism. (2) Methods: We determined miR-33a expression levels following exposure of MCF-7 and MDA-MB-231 breast cancer cells to estrogen receptor (ER) activator (estradiol-17β, E2) or anti-estrogens (ICI 182,780, Fulvestrant, FUL) at non-cytotoxic concentrations. We related miR-33a expression levels in the cells to cellular lipid biosynthesis-related pathways through immunoblotting. (3) Results: miR-33a mimic treatment led to significantly downregulation of fatty acid synthase (FASN) in MCF-7 cells but not in MDA-MB-231 cells in the presence of estradiol-17β (E2) or Fulvestrant (FUL). In contrast to the miR-33a inhibitor effect, miR-33a mimic co-transfection with E2 or FUL led to diminished AMP-activated protein kinase α (AMPKα) activity in MCF-7 cells. E2 increases FASN levels in MDA-MB-231 cells regardless of miR-33a cellular levels. miR-33a inhibitor co-treatment suppressed E2-mediated AMPKα activity in MDA-MB-231 cells. (4) Conclusions: The cellular expression levels of miR-33a are critical to understanding differential responses which include cellular energy sensors such as AMPKα activation status in breast cancer cells

Specific c-Jun N-Terminal Kinase Inhibitor, JNK-IN-8 Suppresses Mesenchymal Profile of PTX-Resistant MCF-7 Cells through Modulating PI3K/Akt, MAPK and Wnt Signaling Pathways

Paclitaxel (PTX) is a widely used chemotherapeutic agent in the treatment of breast cancer, and resistance to PTX is a common failure of breast cancer therapy. Therefore, understanding the effective molecular targets in PTX-resistance gains importance in identifying novel strategies in successful breast cancer therapy approaches. The aim of the study was to investigate the functional role of PTX resistance on MCF-7 cell survival and proliferation related to PI3K/Akt and MAPK pathways. The generated PTX-resistant (PTX-res) MCF-7 cells showed enhanced cell survival, proliferation, and colony formation potential with decreased cell death compared to wt MCF-7 cells. PTX-res MCF-7 cells exhibited increased motility profile with EMT, PI3K/Akt, and MAPK pathway induction. According to the significant SAPK/JNK activation in PTX-res MCF-7 cells, specific c-Jun N-terminal kinase inhibitor, JNK-IN-8 is shown to suppress the migration potential of cells. Treatment of JNK inhibitor suppressed the p38 and SAPK/JNK and Vimentin expression. However, the JNK inhibitor further downregulated Wnt signaling members in PTX-res MCF-7 cells. Therefore, the JNK inhibitor JNK-IN-8 might be used as a potential therapy model to reverse PTX-resistance related to Wnt signaling

Celastrol Modulates Lipid Synthesis via PI3K/Akt/mTOR Signaling Axis to finalize Cell Death Response in Prostate Cancer Cells

FASN is key enzyme during lipid biogenesis is associated with prostate cancer. In this study, we aim to investigate the potential role of celastrol, root extracts of Tripterygium wilfordii on modulation of lipid biosynthesis-associated PI3K/Akt signaling. To determine the effect of celastrol on cell viability, prostate cancer cells were exposed with celastrol in dose dependent manner. AR (+) LNCaP and AR (−) DU145 and PC3 cell viability were inhibited by celastrol with IC50 in the range of 0.05–1 µM. To address the role of celastrol on cell death mechanism, celastrol-treated prostate cancer cells were evaluated with immunoblotting and flow cytometric analysis. Celastrol significantly upregulated PARP and caspase 9 cleavage also increased sub-G1 population. Celastrol also inhibited cell migration and invasion. These effects were associated with decreased PI3K/Akt signaling axis and downregulation of epithelial mesenchymal transition in prostate cancer cells. Likewise, lipid biosynthesis was downregulated with celastrol, however inhibition of PI3K/Akt signaling axis via LY294002 further decrease the cell migration and proliferation rate in prostate cancer cells. Our data suggest that, celastrol suppressed cell proliferation via inhibition of lipid biosynthesis through downregulation of PI3K/Akt signal axis. Targeting lipid metabolism-related enzymes in prostate cancer may offer new avenues for therapeutic approaches

AMPK Is the Crucial Target for the CDK4/6 Inhibitors Mediated Therapeutic Responses in PANC-1 and MIA PaCa-2 Pancreatic Cancer Cell Lines

The survival rate of pancreatic ductal adenocarcinoma (PDAC) patients is short, and PDAC is a cancer type that ranks fourth in the statistics regarding death due to cancer. Mutation in the KRAS gene, which plays a role in pancreatic cancer development, activates the PI3K/AKT/mTOR signaling pathway. The activity of the AMPK as a cellular energy sensor is one of the fundamental mechanisms that can induce effective therapeutic responses against CDK4/6 inhibitors via adjusting the cellular and tumor microenvironment stress management. The phosphorylation of AMPKα at the different phosphorylation residues such as Thr172 and Ser 377 causes metabolic differentiation in the cells following CDK4/6 inhibitor treatment in accordance with an increased cell cycle arrest and senescence under the control of different cellular players. In this study, we examined the competencies of the CDK4/6 inhibitors LY2835219 and PD-0332991 on the mechanism of cell survival and death based on AMPK signaling. Both CDK4/6 inhibitors LY2835219 and PD-0332991 modulated different molecular players on the PI3K/AKT/mTOR and AMPK signaling axis in different ways to reduce cell survival in a cell type dependent manner. These drugs are potential inducers of apoptosis and senescence that can alter the therapeutic efficacy cells

Autocrine Growth Hormone-Triggered Curcumin Resistance Abolished by NF-κB Signaling Pathway Dependent on Inflammatory Cytokines and Active Polyamine Catabolic Machinery in MCF-7, MDA-MB-453 and MDA-MB-231 Breast Cancer Cells

Autocrine Growth Hormone (GH) induces cell growth, proliferation metastasis in breast cancer. Curcumin is a promising therapeutic agent in cancer through affecting different molecular targets. Our aim was to demonstrate the molecular machinery of curcumin-mediated apoptosis in autocrine GH + MCF-7, MDA-MB-453 and MDA-MB-231 breast cancer cells (BCCs). Stable GH expressing BCCs were generated by GH gene insert PC3.1 plasmid transfection and Neomycin selection. Although GH + cells are resistant to curcumin treatment, dose-dependent drug exposure decreased cell viability, inhibited colony formation, invasion-metastasis via suppressing GH expression in each BCCs. Anti-hormonal concentration of curcumin (20 µM for MCF-7, MDA-MB-453 and 25 µM for MDA-MB-231) inhibited NF-κB p65 (Ser 536) phosphorylation and decreased DNA binding activity of NF-κB p65 in autocrine GH expressing BCCs. In addition, autocrine GH-mediated IL-1α, IL-6, IL-1β pro-inflammatory cytokine expressions downregulated by curcumin treatment. Moreover, curcumin overcome autocrine GH triggered drug resistant and induced caspase-mediated apoptotic cell death through activating Polyamine (PA) catabolic pathway enzymes which led to generation of toxic by-products such as H2O2 in MCF-7, MDA-MB-453 and MDA-MB-231 GH + BCCs. In conclusion, curcumin could overcome GH-mediated resistant phenotype via modulating NF-κB-mediated inflammatory cytokine expression and PA catabolic machinery activation in breast cancer cells