Targeting calcium signaling in cancer therapy

Cell regulation

Background: Using small molecule smoothened (SMO) antagonists, Hedgehog (HH) signaling had been implicated to play an important role in a variety of cancers (e.g. Brain, Lung, Pancreas, digestive tract etc.). Recently, based on studies in a selected set of pancreatic and colorectal cancer cells it has been suggested: a) earlier observation of HH signaling dependence of various cancers by others and us is due to non-specific effect of SMO antagonists; b) HH producing cancer cells do not have a functional HH pathway; c) HH signaling is not required for the growth or survival of cancer cells rather it affects the growth of tumor by activating HH pathway in stroma cells. Given the reported prevalence of HH signaling in cancers and the suggested implication of this latter work on devising a successful cancer therapy, we decided to investigate the role of HH signaling in cancer in a manner independent of SMO antagonist. Lung cancer, being one of the deadliest cancers with the reported higher incidence of HH signaling, was used as a test system to evaluate the basic assumptions of this recently proposed model of HH role in cancer. Objective: Define the role of HH signaling in cancer cells. Methodology: The human non-small cell lung carcinoma (NSCLC) cell lines (HOP62, A549, U1752, H23, H157, H522) were used as a model system to study the relevance of HH signaling in cancer cells. The HH signaling was modulated by shRNA mediated knockdown of various HH signaling components (e.g. SMO, GLI1, SHH). The lentiviruses expressing shRNA were made and used to deliver the shRNA in NSCLC cells. HH responsiveness (quantitative real time RT-PCR and western blotting), cell proliferation (ATP quantitation), survival (Annexin-V labeling), anchorage independent growth (soft agar assay) and tumorigenesis (xenografts in Nu/Nu nude mice) were evaluated following shRNA mediated attenuation of HH signaling. Currently, HH pathway activation in cancer and stroma cells of primary lung cancer samples is being evaluated by immunohistochemistry (IHC) and RNA in situ hybridization (ISH). Preliminary Results and Conclusions: Exogenous expression of SHH in HOP62 and A549 induced the HH target gene GLI1 and PTCH1 expression while shRNA mediated knockdown of HH pathway components (e.g. SMO, SHH) inhibited the HH target gene expression. Further more, knockdown of HH pathway components, attenuated the proliferation, increased the apoptosis while decreased the anchorage independent growth of tested lung cancer cell lines. GLI1 shRNA mediated attenuation of HH signaling in A549 cells, greatly reduced their tumorigenicity in nude mice. We anticipate seeing activated HH signaling in cancer and stroma cells of primary lung tumor samples by IHC and ISH. Together, these results would indicate that cancer cells do elaborate a functional HH signaling pathway and require HH signaling for growth, survival and tumorigenicity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-430. doi:10.1158/1538-7445.AM2011-LB-430

Background: The pesticide atrazine does not bind to or activate the classical estrogen receptor (ER), but it up-regulates the aromatase activity in estrogen-sensitive tumor cells. The G protein estrogen receptor (GPR30/GPER) has been reported to be involved in certain biological responses to endogenous estrogens and environmental compounds exerting estrogen-like activity.Objectives: We aimed to evaluate the potential of atrazine to trigger GPER-mediated signaling in cancer cells and cancer-associated fibroblasts (CAFs).Methods and Results: Using gene reporter assays in diverse types of cancer cells, we found that atrazine did not transactivate endogenous ERα or chimeric proteins that encode the ERα and ERβ hormone binding domains. Conversely, atrazine was able to bind to GPER to induce ERK activation and the expression of estrogen target genes, which, interestingly, appeared to rely on both GPER and ERα expression. As a biological counterpart, atrazine stimulated the proliferation of ovarian cancer cells that depend on GPER and ERα, as evidenced by gene silencing experiments and the use of specific signaling inhibitors. Of note, through GPER, atrazine elicited ERK phosphorylation, gene expression, and migration in CAFs, thus extending its stimulatory role to these main players of the tumor microenvironment.Conclusions: Our results suggest a novel mechanism through which atrazine may exert relevant biological effects in cancer cells and CAFs. On the basis of our data, atrazine should be included among the environmental contaminants that may elicit estrogenic activity through GPER-mediated signaling.Citation: Albanito L, Lappano R, Madeo A, Chimento A, Prossnitz ER, Capello AR, Dolce V, Abonante S, Pezzi V, Maggiolini M. 2015. Effects of atrazine on estrogen receptor α– and G protein–coupled receptor 30–mediated signaling and proliferation in cancer cells and cancer-associated fibroblasts. Environ Health Perspect 123:493–499; http://dx.doi.org/10.1289/ehp.1408586

The phosphoinositide 3-kinase/3-phosphoinositide-dependent kinase 1 (PDK1)/Akt signaling pathway plays a key role in cancer cell growth, survival, and tumor angiogenesis and represents a promising target for anticancer drugs. Here, we describe three potent PDK1 inhibitors, BX-795, BX-912, and BX-320 (IC(50) = 11-30 nm) and their initial biological characterization. The inhibitors blocked PDK1/Akt signaling in tumor cells and inhibited the anchorage-dependent growth of a variety of tumor cell lines in culture or induced apoptosis. A number of cancer cell lines with elevated Akt activity were >30-fold more sensitive to growth inhibition by PDK1 inhibitors in soft agar than on tissue culture plastic, consistent with the cell survival function of the PDK1/Akt signaling pathway, which is particularly important for unattached cells. BX-320 inhibited the growth of LOX melanoma tumors in the lungs of nude mice after injection of tumor cells into the tail vein. The effect of BX-320 on cancer cell growth in vitro and in vivo indicates that PDK1 inhibitors may have clinical utility as anticancer agents.

Accumulating lines of evidence have revealed that microRNAs (miRNAs) play critical roles in many biological processes, such as carcinogenesis, angiogenesis, programmed cell death, cell proliferation, invasion, migration, and differentiation. They act either as tumour suppressors or oncogenes, and alteration in their expression patterns has been linked to onset, progression and chemoresistance of various cancers. Moreover, miRNAs are also crucial for the regulation of cancer stem cells (CSCs) self-renewal and proliferation as well as control of Epithelial-to-Mesenchymal Transition (EMT) of cancer cells. Therefore, exploitation of miRNAs as targets for cancer prevention and therapy could be a promising approach. Several experimental and epidemiologic studies have shown that dietary intake of natural agents such as baicalin, ginsenoside, curcumin, resveratrol, genistein, epigallocatechin-3-gallate (EGCG), indole-3-carbinol, 3,3΄-diindolylmethane (DIM) including antioxidants among others is inversely associated with the risk for cancer, demonstrating the inhibitory effects of natural agents on carcinogenesis. Moreover, the anticancer agents from natural plants have been found to inhibit the development and progression of cancer through the regulation of cellular signaling pathways. Importantly, natural agents also up-regulate the expression of tumor-suppressive miRNAs and down-regulate the expression of oncogenic miRNAs, leading to the inhibition of cancer cell growth and cancer stem cell self-renewal through modulation of cellular signaling network. Furthermore, natural agents also regulate epigenetically deregulated DNAs and miRNAs, leading to the normalization of altered cellular signaling in cancer cells. Therefore, natural agents could have much broader use in the prevention and/or treatment of various types of cancer in combination with conventional chemotherapeutics. However, more in vitro mechanistic experiments, in vivo animal studies, and clinical trials are needed to realize the true value of natural agents in the prevention and/or treatment of cancer. Herein, we provide an overview of natural agents’ modulation of miRNA expression as well as highlight the significance of these observations as potential new strategies in cancer therapies. This review will help us to know in detail how miRNAs are regulated by natural agents and also help to develop more effective and secure natural agents for clinical therapies.

Desmoplasia of Pancreatic Ductal Adenocarcinoma

Emerging Role of Semaphorins as Major Regulatory Signals and Potential Therapeutic Targets in Cancer

EGFL6, a member of the EGF-like superfamily, plays an important role during embryonic development and has been implicated in promotion of tumor angiogenesis without affecting wound healing. There is very little known about the function of EGFL6 in cancer cells. Here, we investigated whether EGFL6 plays a direct role in cancer cells in addition to the promotion of tumor angiogenesis. Our study showed that EGFL6 promoted epithelial-mesenchymal transition (EMT) and stemness of breast cancer cells and increased cell migration and invasion in cell culture studies. We also found that EGFL6 reduced apoptotic signaling in cancer cells and promoted tumor growth in vivo. Importantly, expression of EGFL6 in cancer cells and tumor endothelial cells not only increased tumor angiogenesis but also promoted migration of cancer cells. Such dual engagement of cancer and stromal cells suggests crosstalk mediated by EGFL6 in the tumor microenvironment. Blockade of EGFL6 using our novel anti-EGFL6 monoclonal antibody significantly reduced cancer cell migration, tumor angiogenesis, and tumor growth in mouse xenograft tumor models. Silencing EGFL6 mRNA by shRNA transfection of cancer cells also significantly reduced cancer cell migration, tumor angiogenesis, and tumor growth in mouse xenograft tumor models. Taken together, the results of this study indicate that targeting EGFL6 is a unique strategy for inhibiting both cancer cell metastasis and tumor angiogenesis.

Cancer remains one of the debilitating health threats to mankind in view of its incurable nature. Many factors are complicit in the initiation, progression and establishment of cancers. Early detection of cancer is the only window of hope that allows for appreciable management and possible limited survival. However, understanding of cancer biology and knowledge of the key factors that interplay at multi-level in the initiation and progression of cancer may hold possible avenues for cancer treatment and management. In particular, dysregulation of growth factor signaling such as that of transforming growth factor beta (TGF-β) and its downstream mediators play key roles in various cancer subtypes. Expanded understanding of the context/cell type-dependent roles of TGF-β and its downstream signaling mediators in cancer may provide leads for cancer pharmacotherapy. Reliable information contained in original articles, reviews, mini-reviews and expert opinions on TGF-β, cancer and the specific roles of TGF-β signaling in various cancer subtypes were retrieved from major scientific data bases including PubMed, Scopus, Medline, Web of Science core collections just to mention but a sample by using the following search terms: TGF-β in cancer, TGF-β and colorectal cancer, TGF-β and brain cancer, TGF-β in cancer initiation, TGF-β and cell proliferation, TGF-β and cell invasion, and TGF-β-based cancer therapy. Retrieved information and reports were carefully examined, contextualized and synchronized into a coherent scientific content to highlight the multiple roles of TGF-β signaling in normal and cancerous cells. From a conceptual standpoint, development of pharmacologically active agents that exert non-specific inhibitory effects on TGF-β signaling on various cell types will undoubtedly lead to a plethora of serious side effects in view of the multi-functionality and pleiotropic nature of TGF-β. Such non-specific targeting of TGF-β could derail any beneficial therapeutic intention associated with TGF-β-based therapy. However, development of pharmacologically active agents designed specifically to target TGF-β signaling in cancer cells may improve cancer pharmacotherapy. Similarly, specific targeting of downstream mediators of TGF-β such as TGF-β type 1 and II receptors (TβRI and TβRII), receptor-mediated Smads, mitogen activated protein kinase (MAPK) and importing proteins in cancer cells may be crucial for cancer pharmacotherapy.

Targeting dysregulated Ca2+ signaling in cancer cells is an emerging chemotherapy approach. This group previously reported that store‐operated Ca2+ entry (SOCE) blocker, such as RP4010, could effectively inhibit intracellular Ca2+ oscillations and cell proliferation in esophageal cancer, a leading cancer worldwide with low 5‐year survival rate. While many current clinical chemotherapy drugs, such as tyrosine kinase inhibitors (TKIs) can induce intracellular Ca2+ release, it is not known whether combination of SOCE blockers and TKIs could achieve better chemotherapy effects. The present study employed both experimental and mathematical models to evaluate the effect of RP4010 and TKI (Afatinib) on intracellular Ca2+ oscillation periods in KYSE‐150 cells, an esophageal cancer cell line. The intracellular Ca2+ oscillation period in KYSE‐150 cells was measured as ~32.8 sec; both Afatinib and RP4010 could reduce intracellular Ca2+ and prolong the period in a dose‐dependent manner. Using a modified canonical model with variables of SOCE channel and IP3 receptor affected by RP4010 and Afatinib receptively, the intracellular Ca2+ oscillation dynamics were simulated. The theoretical data of the combined implementations of drugs also fitted well with experimental data. Both results demonstrated a synergetic effect of RP4010 and Afatinib on inhibiting intracellular Ca2+ oscillation period, which was further confirmed by cell proliferation analysis. This study suggests that experimental and mathematical modeling of intracellular Ca2+ dynamics could be used as a rapid and cost‐effective tool for evaluation of combined chemotherapy drugs.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Rottlerin induces Wnt co-receptor LRP6 degradation and suppresses both Wnt/β-catenin and mTORC1 signaling in prostate and breast cancer cells

Adipocyte is the most predominant cell type in the tumor microenvironment of breast cancer and plays a pivotal role in cancer progression, yet the underlying mechanisms and functional mediators remain elusive. We isolated primary preadipocytes from mammary fat pads of human breast cancer patients and generated mature adipocytes and cancer-associated adipocytes (CAAs) in vitro. The CAAs exhibited significantly different gene expression profiles as assessed by transcriptome sequencing. One of the highly expressed genes in CAAs is granulocyte colony-stimulating factor (G-CSF). Treatment with recombinant human G-CSF protein or stable expression of human G-CSF in triple-negative breast cancer (TNBC) cell lines enhanced epithelial–mesenchymal transition, migration, and invasion of cancer cells, by activating Stat3. Accordantly, targeting G-CSF/Stat3 signaling with G-CSF-neutralizing antibody, a chemical inhibitor, or siRNAs for Stat3 could all abrogate CAA- or G-CSF-induced migration and invasion of breast cancer cells. The pro-invasive genes MMP2 and MMP9 were identified as target genes of G-CSF in TNBC cells. Furthermore, in human breast cancer tissues, elevated G-CSF expression in adipocytes is well correlated with activated Stat3 signal in cancer cells. Together, our results suggest a novel strategy to intervene with invasive breast cancers by targeting CAA-derived G-CSF.

Polymerase Slippage Restoration of Frameshifted TGFBR2 in Colorectal Cancer: A Novel Paradigm

Bacterial minicells to the rescue: cyto-Immunotherapy for the treatment of late stage cancers with minimal to no toxicity.

Cancer is classified into metabolic and/or genetic disorders; notably, the tryptophan catabolism pathway is vital in different cancer types. Here, we focused on the interaction and molecular connection between the cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) receptor and indoleamine-2,3-dioxygenase (IDO) enzyme.To test the impact of the selected immunotherapies on breast cancer cell migration and cell survival, we used in vitro assays. Also, we test the impact of anti-CTLA-4 antibody on the IDO-positive cells.The results of cell migration and clonogenic assays showed that anti-CTLA-4 antibody reduces cancer cell migration and clonogenic abilities of murine breast cancer cells. In addition, the result of flow cytometry showed that the anti-CTLA-4 antibody did not change the percentage of IDO-positive cancer cells. Notably, administrating an IDO blocker, 1-Methyl-DL-tryptophan (1MT), reduces the efficiency of the antiCTLA-4 antibody.The enzymatic blocking of the IDO reduces the efficiency of the anti-CTLA-4 antibody on cell migration and clonogenic abilities suggesting that there is an inhibitory interaction at the molecular level between functions of CTLA-4 and IDO. It is unclear via which mechanism(s) IDO interacts with CTLA-4 signaling and also why blocking IDO makes disruption in CTLA-4 signaling in cancer cells. Indeed, evaluating the role of IDO in CTLA-4 signaling in cancer cells may assist in clarifying a poor response to CTLA-4 immunotherapies by some patients. Hence, further investigation of the molecular interaction between CTLA-4 and IDO might help to improve the efficiency of CTLA-4 immunotherapy.