Inhibition of Autophagy Enhances the Antitumor Effect of Thioridazine in Acute Lymphoblastic Leukemia Cells

Hypoxia-initiated Cysteine-rich protein 61 secretion promotes chemoresistance of acute B lymphoblastic leukemia cells

The drug resistance is a major obstacle in acute B-lymphoblastic leukemia (B-ALL) treatment. Our previous study has indicated that increased levels of Cysteine-rich protein 61 (Cyr61) in the bone marrow can mitigate the chemosensitivity of B-ALL cells, though the specific source of Cyr61 in the bone marrow remains unknown. In this study, we aimed to investigate whether hypoxia can induce Cyr61 production in B-ALL cells, delineates the underlying mechanisms, and evaluates the effect of Cyr61 on the chemosensitivity of B-ALL cells under hypoxia conditions. The results indicate that hypoxia promotes Cyr61 production in B-ALL cells by activating the NF-κB pathway. Increased Cyr61 expression appears to reduce the chemosensitivity of B-ALL cell to vincristine (VCR) and daunorubicin (DNR) through autophagy under hypoxia. Notably, inhibition of Cyr61 restores the chemosensitivity of B-ALL cells to both chemotherapeutic agents. This study is the first time to report that hypoxia decreases the chemosensitivity of B-ALL cells by inducing Cyr61 production, suggesting that targeting Cyr61 or its associated pathways could potentially improve the clinical response of B-ALL patients.

Polyamidoamine Dendrimers Functionalized with ZnO-Chitosan Nanoparticles as an Efficient Surface for L-asparaginase Immobilization

In this study, the third-generation polyamidoamine dendrimer was functionalized with a 5-amino-1H-tetrazole heterocycle to load the synthesis enzyme and its surface groups. Then, chitosan was attached to the dendrimer by a suitable linker, and finally, zinc oxide nanoparticles were inserted into dendrimer cavities to increase loading. FTIR, FESEM, TEM, and DLS analysis showed that this new dendrimer has specific branches, and ZnO nanoparticles were spread between the branches and connected with the branches and chitosan biopolymer. Also proved the presence of stabilized L-asparaginase enzyme and ZnO nanoparticles in the designed system. Furthermore, the extent of L-asparaginase enzyme loading and release was investigated in the laboratory with a dialysis bag. Examining the toxicity of the new third-generation polyamidoamine (PAMAM) dendrimeric nanocarrier based on chitosan-zinc oxide biopolymer (PAMAM-G3@ZnO-Cs nanocarrier) on the Jurkat cell line (human acute lymphoblastic leukemia) at pH 7.4 showed that this nanocarrier effectively encapsulates the drug L-asparaginase and slowly releases it and also preventing the growth of cancer cells. The activity of the loaded enzyme in the nanocarrier and the free enzyme was calculated. During the investigations, it was found that the enzyme attached to the nanocarrier is more stable than the free enzyme at optimal pH and temperature and at high temperatures, acidic and basic pHs. Vmax and Km values were lower for loaded enzymes. The synthesized PAMAM-G3@ZnO-Cs nanocarrier can be a promising candidate in the pharmaceutical industry and medical science for cancer treatment due to its biocompatibility, non-toxicity, stability, and slow release of L-asparaginase.

New phenothiazine conjugates as apoptosis inducing agents: Design, synthesis, In-vitro anti-cancer screening and 131I-radiolabeling for in-vivo evaluation

Phenothiazines (PTZs) are a group of compounds characterized by the presence of the 10H-dibenzo-[b,e]-1,4-thiazine system. PTZs used in clinics as antipsychotic drugs with other diverse biological activities. The current aim of the study is to investigate and understand the effect of potent PTZs compounds using a group of In-vitro and In-vivo assays. A total of seventeen novel phenothiazine derivatives have been designed, synthesized, and evaluated primarily in-vitro for their ability to inhibit proliferation activity against NCI-60 cancer cell lines, including several multi-drug resistant (MDR) tumor cell lines. Almost all compounds were active and displayed promising cellular activities with GI50 values in the sub-micromolar range. Four of the most promising derivatives (4b, 4h, 4g and 6e) have been further tested against two selected sensitive cancer cell lines (colon cancer; HCT-116 and breast cancer; MDA-MB231). The apoptosis assay showed that all the selected compounds were able to induce early apoptosis and compound 6e was able to induce additional cellular necrosis. Cell cycle assay showed all selected compounds were able to induce cell cycle arrest at sub-molecular phase of G0-G1 with compound 6e induced cell cycle arrest at G2M in HCT-116 cells. Accordingly, the apoptotic effect of the selected compounds was extensively investigated on genetic level and Casp-3, Casp-9 and Bax gene were up-regulated with down-regulation of Bcl-2 gene suggesting the activation of both intrinsic and extrinsic pathways. In-vivo evaluation of the antitumor activity of compound 4b in solid tumor bearing mice showed promising therapeutic effect with manifestation of dose and time dependent toxic effects at higher doses. For better evaluation of the degree of localization of 4b, its 131I-congener (131I-4b) was injected intravenously in Ehrlich solid tumor bearing mice that showed good localization at tumor site with rapid distribution and clearance from the blood. In-silico study suggested NADPH oxidases (NOXs) as potential molecular target. The compounds introduced in the current study work provided a cutting-edge phenothiazine hybrid scaffold with promising anti-proliferation action that may suggest their anti-cancer activity.

Inhibition of PI3K Signaling Intensified the Antileukemic Effects of Pioglitazone: New Insight into the Application of PPARγ Stimulators in Acute Lymphoblastic Leukemia

Over the past two decades, molecular targeted therapy has revolutionized the landscape of cancer treatment due to lower side effects as well as higher anticancer effects. Peroxisome proliferator-activated receptor gamma (PPARγ) is a member of the nuclear hormone receptor which plays a crucial role in cell proliferation and death and the efficacy of PPARγ ligands either as monotherapy or in combination with traditional chemotherapy drugs has been proved by recent studies. In this study, we aimed to investigate the effects of pioglitazone, a well-known PPARγ stimulator, in ALL-derived NALM6 cells by using trypan blue assay, MTT assay, and flow cytometry analysis. Moreover, to investigate the molecular mechanism action of pioglitazone in these cells, we assessed the possible alterations in the expression of some target genes which regulate cell proliferation, apoptosis, and autophagy system. Our result demonstrated that pioglitazone induced a remarkable antileukemic effect on NALM6 cells through a PTEN-mediated manner. Based on the fact that PI3K hyperactivation is one of the main properties of ALL cells, the effects of PI3K inhibition using CAL-101 on pioglitazone-induced cytotoxicity were evaluated by combinatorial experiments. Moreover, the result of cell cycle assay and qRT-PCR demonstrated that pioglitazone-CAL-101 induced antileukemic effect mainly through induction of p21 and p27-mediated G1 arrest. Additionally, our result showed that inhibition of proteasome and autophagy system, two main cellular processes, increased the antileukemic effects of the agents. Taken together, we suggest a novel therapeutic application for PPARγ stimulators as a single agent or in combination with PI3K inhibitors that should be clinically evaluated in ALL patients.

The role of phenothiazine derivatives in autophagy regulation: A systematic review

In this review, we summarized the current literature on the impact of phenothiazine derivatives on autophagy in vitro. Phenothiazines are antipsychotic drugs used in the treatment of schizophrenia, which is related to altered neurotransmission and dysregulation of neuronal autophagy. Thus, phenothiazine derivatives can impact autophagy. We identified 35 papers, where the use of the phenothiazines in the in vitro autophagy assays on normal and cancer cell lines, Caenorhabditis elegans, and zebrafish were discussed. Chlorpromazine, fluphenazine, mepazine, methotrimeprazine, perphenazine, prochlorperazine, promethazine, thioridazine, trifluoperazine, and novel derivatives can modulate autophagy. Stimulation of autophagy by phenothiazines may be either mammalian target of rapamycin (mTOR)-dependent or mTOR-independent. The final effect depends on the used concentration as well as the cell line. A further investigation of the mechanisms of autophagy regulation by phenothiazine derivatives is required to understand the biological actions and to increase the therapeutic potential of this class of drugs.

Targeting Ca2+ and Mitochondrial Homeostasis by Antipsychotic Thioridazine in Leukemia Cells

Mitochondria have pivotal roles in cellular physiology including energy metabolism, reactive oxygen species production, Ca2+ homeostasis, and apoptosis. Altered mitochondrial morphology and function is a common feature of cancer cells and the regulation of mitochondrial homeostasis has been identified as a key to the response to chemotherapeutic agents in human leukemias. Here, we explore the mechanistic aspects of cytotoxicity produced by thioridazine (TR), an antipsychotic drug that has been investigated for its anticancer potential in human leukemia cellular models. TR exerts selective cytotoxicity against human leukemia cells in vitro. A PCR array provided a general view of the expression of genes involved in cell death pathways. TR immediately produced a pulse of cytosolic Ca2+, followed by mitochondrial uptake, resulting in mitochondrial permeabilization, caspase 9/3 activation, endoplasmic reticulum stress, and apoptosis. Ca2+ chelators, thiol reducer dithiothreitol, or CHOP knockdown prevented TR-induced cell death. TR also exhibited potent cytotoxicity against BCL-2/BCL-xL-overexpressing leukemia cells. Additionally, previous studies have shown that TR exhibits potent antitumor activity in vivo in different solid tumor models. These findings show that TR induces a Ca2+-mediated apoptosis with involvement of mitochondrial permeabilization and ER stress in leukemia and it emphasizes the pharmacological potential of TR as an adjuvant in antitumor chemotherapy.