Pharmacological induction of cell surface GRP78 contributes to apoptosis in triple negative breast cancer cells

Predictive Value and Immunological Role of the HSPA5 Gene in Cervical Cancer

Cervical cancer (CC) ranks fourth among women's malignancies worldwide and seriously affects women's health. HSPA5 is a heat shock protein, also known as glucose regulatory protein 78 (GRP78). Upregulation of HSPA5 has been reported to be closely associated with multiple types of tumors. However, the specific role of HSPA5 in cervical cancer has not been discovered. In our study, we explored the prognostic value of HSPA5 in CC. Here, we analyzed the (TCGA) and (UCSC) databases, the analysis of HSPA5 in many tumors types was conducted with the "wilcox. test" method. A False Discovery Rate (FDR) value < 0.05 and Log2 | (fold change, FC) |> 1 were set as the cutoffs. "*", "**", and "***" indicate FDR < 0.05, < 0.01, and < 0.001, respectively, and further used human cervical cancer cells for q-PCR and western blotting detection. q-PCR and western blotting results showed that HSPA5 was highly expressed in cervical cancer cells, while it was expressed at low levels in normal cells (P < 0.05).We also analyzed the immunohistochemical data. immunohistochemical analysis results showed that HSPA5 was highly expressed in human cervical cancer, while it was expressed at low levels in normal tissues (P < 0.05). Analysis in TCGA-UCSC showed that the proportion of G3 in the group with high expression of HSPA5 was relatively high (P < 0.05). Enrichment analysis and survival analysis showed that the increased expression of HSPA5 in cervical cancer was related to the survival of CC and was involved in the regulation of biological behavior and molecular signaling pathways of cervical cancer. The correlation analysis of immune checkpoint and immune infiltration showed that HSPA5 was involved in the regulation of immune process of cervical cancer (P < 0.05). Drug sensitivity correlation analysis showed that HSPA5 was a sensitive target for tumor drugs (P < 0.05). In brief, those results suggest that HSPA5 can act as an oncogene of CC development and can serve as an effective predictive biomarker in cervical cancer.

Chemotherapy-Induced Cell-Surface GRP78 Expression as a Prognostic Marker for Invasiveness of Metastatic Triple-Negative Breast Cancer

Metastasis remains the leading cause (90%) of cancer-related mortality, especially in metastatic triple-negative breast cancer (TNBC). Improved understanding of molecular drivers in the metastatic cascade is crucial, to find accurate prognostic markers for invasiveness after chemotherapy treatment. Current breast cancer chemotherapy treatments include doxorubicin and paclitaxel, inducing various effects, such as the unfolded protein response (UPR). The key regulator of the UPR is the 78-kDa glucose-regulated protein (GRP78), which is associated with metastatic disease, although, its expression level in the context of invasiveness is still controversial. We evaluate doxorubicin effects on TNBC cells, identifying GRP78 subpopulations linked to invasiveness. Specifically, we evaluate the motility and invasiveness of GRP78 positive vs. negative cell subpopulations by two different assays: the in vitro Boyden chamber migration assay and our innovative, rapid (2-3 h) clinically relevant, mechanobiology-based invasiveness assay. We validate chemotherapy-induced increase in the subpopulation of cell-surface GRP78(+) in two human, metastatic TNBC cell lines: MDA-MB-231 and MDA-MB-468. The GRP78(+) cell subpopulation exhibits reduced invasiveness and metastatic potential, as compared to whole-population control and to the GRP78(-) cell subpopulation, which are both highly invasive. Thus, using our innovative, clinically relevant assay, we rapidly (on clinical timescale) validate that GRP78(-) cells are likely linked with invasiveness, yet also demonstrate that combination of the GRP78(+) and GRP78(-) cells could increase the overall metastatic potential. Our results and approach could provide patient-personalized predictive marker for the expected benefits of chemotherapy in TNBC patients and potentially reveal non-responders to chemotherapy while also allowing evaluation of the clinical risk for metastasis.

In Vitro Apoptotic and Antiproliferative Activity of Hypericum Perforatum Extract on Human Osteosarcoma Cell Line

Hypericum perforatum (HP) has been widely used as an alternative medicine due to its active pharmacological properties. While the antiproliferative effects of components such as hypericin and hyperforin have been demonstrated in malignant cell lines, most studies have focused on the pharmacological properties of the HP extract itself. Recent research has indicated that HP and its active substances possess anticancer activities; however, there is a lack of studies examining its effects on osteosarcoma. In addition, HP has demonstrated the ability to mitigate the toxicity of several drugs, including chemotherapeutic agents. Hence, the primary objective of this study was to explore the potential anticancer properties of HP in relation to osteosarcoma cells. MG-63 human osteosarcoma cells were cultured and treated with HP extract. Apoptotic factors were analyzed using ELISA, while cell viability was assessed using the MTT test. The results revealed a significant increase in the activities of proapoptotic proteins GRP78, Wee1, apoptosis-inducing factor (AIF), GADD153, Bax, and cleaved caspase-3 in MG-63 osteosarcoma cells after 48 hours of treatment with HP at a concentration of 0.8%. Conversely, the activity of Bcl-2, an antiapoptotic protein, significantly decreased. Moreover, HP extract demonstrated a dose-dependent reduction in cell viability in MG-63 cells. In conclusion, HP extract induces apoptosis in MG-63 osteosarcoma cells by upregulating the expressions of proapoptotic proteins GRP78, Wee1, AIF, GADD153, Bax, and cleaved caspase-3. This study will assist researchers in understanding the importance of alternative treatments using HP in the context of human osteosarcoma therapy, which many researchers are currently unaware of.

Impact of Complex Apoptotic Signaling Pathways on Cancer Cell Sensitivity to Therapy

Anticancer drugs induce apoptotic and non-apoptotic cell death in various cancer types. The signaling pathways for anticancer drug-induced apoptotic cell death have been shown to differ between drug-sensitive and drug-resistant cells. In atypical multidrug-resistant leukemia cells, the c-Jun/activator protein 1 (AP-1)/p53 signaling pathway leading to apoptotic death is altered. Cancer cells treated with anticancer drugs undergo c-Jun/AP-1-mediated apoptotic death and are involved in c-Jun N-terminal kinase activation and growth arrest- and DNA damage-inducible gene 153 (Gadd153)/CCAAT/enhancer-binding protein homologous protein pathway induction, regardless of the p53 genotype. Gadd153 induction is associated with mitochondrial membrane permeabilization after anticancer drug treatment and involves a coupled endoplasmic reticulum stress response. The induction of apoptosis by anticancer drugs is mediated by the intrinsic pathway (cytochrome c, Cyt c) and subsequent activation of the caspase cascade via proapoptotic genes (e.g., Bax and Bcl-xS) and their interactions. Anticancer drug-induced apoptosis involves caspase-dependent and caspase-independent pathways and occurs via intrinsic and extrinsic pathways. The targeting of antiapoptotic genes such as Bcl-2 enhances anticancer drug efficacy. The modulation of apoptotic signaling by Bcl-xS transduction increases the sensitivity of multidrug resistance-related protein-overexpressing epidermoid carcinoma cells to anticancer drugs. The significance of autophagy in cancer therapy remains to be elucidated. In this review, we summarize current knowledge of cancer cell death-related signaling pathways and their alterations during anticancer drug treatment and discuss potential strategies to enhance treatment efficacy.

A nanotherapeutic approach to selectively eliminate metastatic breast cancer cells by targeting cell surface GRP78

Here, rational engineering of doxorubicin prodrug loaded peptide-targeted liposomal nanoparticles to selectively target metastatic breast cancer cells in vivo is described. Glucose-regulated protein 78 (GRP78), a heat shock protein typically localized in the endoplasmic reticulum in healthy cells, has been identified to home to the cell surface in certain cancers, and thus has emerged as a promising therapeutic target. Recent reports indicated GRP78 to be expressed on the cell surface of an aggressive subpopulation of stem-like breast cancer cells that exhibit metastatic potential. In this study, a targeted nanoparticle formulation with a GRP78-binding peptide (Kd of 7.4 ± 1.0 μM) was optimized to selectively target this subpopulation. In vitro studies with breast cancer cell lines showed the targeted nanoparticle formulation (TNPGRP78pep) achieved enhanced cellular uptake, while maintaining selectivity over the control groups. In vivo, TNPGRP78pep loaded with doxorubicin prodrug was evaluated using a lung metastatic mouse model and demonstrated inhibition of breast cancer cell seeding to lungs down at the level of negative control groups. Combined, this study established that specific-targeting of surface GRP78 expressing a subpopulation of aggressive breast cancer cells was able to inhibit breast cancer metastasis to lungs, and underpinned the significance of GRP78 in breast cancer metastasis.

Cell surface GRP78: a potential mechanism of therapeutic resistant tumors

GRP78 is a protein that acts as a chaperone within the endoplasmic reticulum (ER) and has multiple functions. It is induced by stress and abets cells from survival. Despite, multiple Stress conditions like ER, chronic psychological and nutritional stress, hypoxia, chemotherapy, radiation therapy, and drug resistance induce cell surface GRP78 (CS-GRP78) expression in cancer cells. Further, CS-GRP78 is associated with increased malignancy and resistance to anti-cancer therapies and is considered a high-value druggable target. Recent preclinical research suggests that targeting CS-GRP78 with anti-GRP78 monoclonal antibodies (Mab) in combination with other agents may be effective in reversing the failure of chemotherapy, radiotherapy, or targeted therapies and increasing the efficacy of solid tumors treatment. This article will review recent evidence on the role of CS-GRP78 in developing resistance to anti-cancer treatments and the potential benefits of combining anti-GRP78 Mab with other cancer therapies for specific patient populations. Furthermore, our limited understanding of how CS-GRP78 regulated in human studies is a major drawback for designing effective CS-GRP78-targeted therapies. Hence, more research is still warranted to translate these potential therapies into clinical applications.

Cell-Penetrating Peptidic GRP78 Ligand-Conjugated Iron Oxide Magnetic Nanoparticles for Tumor-Targeted Doxorubicin Delivery and Imaging

Although chemotherapy is regarded as an essential option in cancer treatment, it is still far from being perfect. Inadequate tumor drug concentration and systemic toxicity along with broad biodistribution have diminished the utility of chemotherapy. Tumor-targeting peptide-conjugated multifunctional nanoplatforms have emerged as an effective strategy for site-directed tumor tissues in cancer treatment and imaging. Herein, Pep42-targeted iron oxide magnetic nanoparticles (IONPs) functionalized with β-cyclodextrin (ßCD) containing doxorubicin (DOX) (Fe₃O₄-ßCD-Pep42-DOX) were successfully developed. The physical effects of the prepared NPs were characterized by employing various techniques. Transmission electron microscopy (TEM) images disclosed that the developed Fe₃O₄-ßCD-Pep42-DOX nanoplatforms had a spherical morphology and a core-shell structure with a size of nearly 17 nm. Fourier transform infrared (FT-IR) spectroscopy showed that β-cyclodextrin, DOX, and Pep42 molecules were successfully loaded on the IONPs. In vitro cytotoxicity analysis revealed that the fabricated multifunctional Fe₃O₄-ßCD-Pep42 nanoplatforms possessed excellent biosafety toward BT-474, MDA-MB468 (cancerous cells), and MCF10A normal cells, while Fe₃O₄-ßCD-Pep42-DOX exhibited great cancer cell killing ability. The high cellular uptake along with intracellular trafficking of Fe₃O₄-ßCD-Pep42-DOX highlights the usefulness of the Pep42-targeting peptide. In vivo results strongly supported the in vitro results, i.e., significant tumor size reduction was observed by single-dose injection of Fe₃O₄-ßCD-Pep42-DOX into tumor-bearing mice. Interestingly, in vivo MR imaging (MRI) of Fe₃O₄-ßCD-Pep42-DOX revealed T₂ contrast improvement in the tumor cells and therapeutic ability in cancer theranostics. Taken together, these findings provided strong evidence for the potential capability of Fe₃O₄-ßCD-Pep42-DOX as a multifunctional nanoplatform in cancer therapy and imaging and opens up a new avenue of research in this area.

Triazoles with inhibitory action on P2X7R impaired the acute inflammatory response in vivo and modulated the hemostatic balance in vitro and ex vivo

OBJECTIVE

The present study aimed to investigate five triazole compounds as P2X7R inhibitors and evaluate their ability to reduce acute inflammation in vivo.

MATERIAL

The synthetic compounds were labeled 5e, 8h, 9i, 11, and 12.

TREATMENT

We administered 500 ng/kg triazole analogs in vivo, (1-10 µM) in vitro, and 1000 mg/kg for toxicological assays.

METHODS

For this, we used in vitro experiments, such as platelet aggregation, in vivo experiments of paw edema and peritonitis in mice, and in silico experiments.

RESULTS

The tested substances 5e, 8h, 9i, 11, and 12 produced a significant reduction in paw edema. Molecules 5e, 8h, 9i, 11, and 12 inhibited carrageenan-induced peritonitis. Substances 5e, 8h, 9i, 11, and 12 showed an anticoagulant effect, and 5e at a concentration of 10 µM acted as a procoagulant. All derivatives, except for 11, had pharmacokinetic, physicochemical, and toxicological properties suitable for substances that are candidates for new drugs. In addition, the ADMET risk assessment shows that derivatives 8h, 11, 5e, and 9i have high pharmacological potential. Finally, docking tests indicated that the derivatives have binding energies comparable to the reference antagonist with a competitive inhibition profile.

CONCLUSIONS

Together, the results indicate that the molecules tested as antagonist drugs of P2X7R had anti-inflammatory action against the acute inflammatory response.

The Clinicopathological Significance of BiP/GRP-78 in Breast Cancer: A Meta-Analysis of Public Datasets and Immunohistochemical Detection

The endoplasmic reticulum chaperone BiP (also known as GRP-78 or HSPA5) maintains protein folding to allow cell proliferation and survival and has been implicated in carcinogenesis, tumor progression, and therapy resistance. BiP's association with clinical factors and prognostic potential in breast cancer remains unclear. In this work, three types of analysis were conducted to improve the knowledge of BiP's clinicopathological potential: (1) analysis of publicly available RNA-seq and proteomics datasets stratified as high and low quartiles; (2) a systematic review and meta-analysis of immunohistochemical detection of BIP; (3) confirmation of findings by BiP immunohistochemical detection in two luminal-like breast cancer small cohorts of paired samples (pre- vs. post-endocrine therapy, and primary pre- vs. metastasis post-endocrine therapy). The TCGA PanCancer dataset and CPTAC showed groups with high BiP mRNA and protein associated with HER2, basal-like subtypes, and higher immune scores. The meta-analysis of BiP immunohistochemistry disclosed an association between higher BiP positivity and reduced relapse-free survival. BiP immunohistochemistry confirmed increased BiP expression in metastasis, an association of BiP positivity with HER2 expression, and nuclear BiP localization with higher a tumor stage and poor outcome. Therefore, three independent approaches showed that BiP protein is associated with worse outcomes and holds prognostic potential for breast cancer.

Self-Reinforced Cancer Targeting (SRCT) Depending on Reciprocally Enhancing Feedback between Targeting and Therapy

Conventional cancer targeting methodology needs to be reformed to overcome the intrinsic barriers responsible for poor targeting efficiency. This study describes a concept of self-reinforced cancer targeting (SRCT) by correlating targeting with therapy in a reciprocally enhancing manner. SRCT is achieved on the basis of two prerequisites: (1) target molecules have to be expressed on cancer cell membranes but not on normal cells, and (2) notably, their expression on cancer cells must be actively upregulated in response to cellular attack by cancer treatments. As a proof-of-concept, a GRP78-targeting nanovehicle for chemotherapy was designed. Resultant data showed that chemotherapeutic drugs could effectively elevate GRP78 expression on the plasma membranes of cancer cells while having minimal influence on normal cells. DOX pretreatment of cancer cells and tumor tissues can greatly increase the targeting efficacy and therapeutic performance of the prepared GRP78-targeting nanomedicine while somewhat disfavoring the nontargeting counterpart. In vivo and in vitro results demonstrated that this GRP78-targeting nanomedicine could accurately target cancer cells to not only implement chemotherapy but also induce GRP78 upregulation on cancer cells, eventually benefiting continuous cancer-cell-targeted attack by the nanomedicines remaining in the blood circulation or administered in the next dose. The GRP78-targeting nanomedicine displays much better antitumor performance compared with the nontargeting counterpart. SRCT is expected to advance cancer-targeted therapy based on the positive dependency between targeting and therapeutic modalities.

Linking cell-surface GRP78 to cancer: From basic research to clinical value of GRP78 antibodies

Glucose-related protein 78 (GRP78) is a chaperone protein localized primarily in the endoplasmic reticulum (ER) lumen, where it helps in proper protein folding by targeting misfolded proteins and facilitating protein assembly. In stressed cells, GRP78 is translocated to the cell surface (csGRP78) where it binds to various ligands and triggers different intracellular pathways. Thus, csGRP78 expression is associated with cancer, involved in the maintenance and progression of the disease. Extracellular exposition of csGRP78 leads to the production of autoantibodies as observed in patients with prostate or ovarian cancer, in which the ability to target csGRP78 affects the tumor development. Present on the surface of cancer cells and not normal cells in vivo, csGRP78 represents an interesting target for therapeutic antibody strategies. Here we give an overview of the csGRP78 function in the cell and its role in oncogenesis, thereby providing insight into the clinical value of GRP78 monoclonal antibodies for cancer prognosis and treatment.

Chemotherapy Controls Metastasis Through Stimulatory Effects on GRP78 and Its Transcription Factor CREB3L1

To achieve a cure for metastatic breast cancer, further understanding of molecular drivers of the metastatic cascade is essential. Currently, chemotherapy regimens include doxorubicin and paclitaxel which act in part by inducing the unfolded protein response (UPR). The master regulator of the UPR, glucose regulated protein 78 (GRP78), localizes on the surface of tumor cells and is associated with metastatic disease. Cyclic AMP responsive element binding protein 3-like 1 (CREB3L1), a member of the UPR, is a breast cancer metastasis suppressor that acts on cyclic AMP to promote the expression of target genes including GRP78. The aim of the present study was to evaluate the effects of chemotherapy on CREB3L1 and cell-surface GRP78 expression and its association with the development of breast cancer metastasis. For this purpose, we use breast cancer cells migration in vitro assays and an in vivo metastatic mouse model. The results showed that chemotherapy activated CREB3L1 and enhanced cell-surface GRP78 expression specifically in triple-negative breast cancer cells (TNBC), reducing their migration and metastatic potential. CREB3L1 knockout (KO) in the triple negative MDAMB231 cell line using CRISPR/Cas9 technology led to inhibition of GRP78 expression and abrogation of the CREB3L1 metastatic suppression function. Inoculation of CREB3L1-KO MDAMB231 cells into a mouse metastatic model induced a massive metastatic profile which chemotherapy failed to prevent. These findings elucidate a potential pathway to the development of a novel treatment strategy for metastatic TNBC based on modulating CREB3L1 and cell-surface GRP78 expression by chemotherapy and GRP78-targeted drugs.

Cell surface GRP78 signaling: An emerging role as a transcriptional modulator in cancer

Cancer cells acquire dysregulated gene expression to establish specific transcriptional dependencies and their underlying mechanisms that are ultimately responsible for this addictions have not been fully elucidated. Glucose-regulated protein 78 (GRP78) is a stress-inducible, multifunctional, prosurvival, endoplasmic reticulum chaperone in the heat shock protein 70 family. Expression of cell surface GRP78 (CS-GRP78) is associated with increased malignant behavior and resistance to chemotherapy and radiotherapy by endowing various cancer cells with increased proliferative ability, altered metabolism, improved survival, and augmented invasive and metastatic potential. Emerging evidence has highlighted an unusual role of CS-GRP78 in regulating transcription factors (TFs) by mediating various signaling pathways involved in malignant transformation, metabolic reprogramming, and tumor progression. During the last decade, we targeted CS-GRP78 with C38 monoclonal antibody (C38 Mab) in numerous studies, which have highlighted the epigenetic interplay between CS-GRP78 and various TFs including c-MYC, Yes-associated protein/transcriptional coactivator with PDZ-binding motif, c-Fos, and histone acetylation to potentiate subsequent modulation of tumorigenesis, invasion, and metastasis. Here, we summarize the current state of knowledge about the role of CS-GRP78 in cancer development and progression, including epigenetic regulation and sheds light on CS-GRP78 as vulnerable target for cancer therapy. Overall, this review focuses on the mechanisms of TFs that are behind the transcriptional dysregulation in cancer and lays the groundwork for rational therapeutic use of C38 Mab based on CS-GRP78 biology.

GRP78 expression in peripheral blood mononuclear cells is a new predictive marker for the benefit of taxanes in breast cancer neoadjuvant treatment

BACKGROUND

Breast cancer treatment is tailored to the specific cancer subtype. Often, systemic treatment is given prior to surgery. Chemotherapy induces significant endoplasmic reticulum (ER) stress-mediated cell death and upregulation of 78-kDa glucose-regulated protein (GRP78). We hypothesized that chemotherapy induces ER stress not only in the tumor tissue but also in immune cells, which may affect the response to anti-cancer treatment.

METHODS

We determined the surface expression of GRP78 on 15 different peripheral blood mononuclear cell (PBMC) subpopulations in 20 breast cancer patients at three time points of the neoadjuvant treatment, i.e., at baseline, after anthracycline treatment, and after taxanes treatment. For this purpose, we performed flow cytometric analyses and analyzed the data using ANOVA and the Tukey test. Serum cytokine levels were also evaluated, and their levels were correlated with response to treatment using the t-test after log transformation and Mann-Whitney U Wilcoxon W test.

RESULTS

A significant increase in GRP78 expression in PBMCs was documented during the taxane phase, only in patients who achieved pathological complete response (pCR). GRP78-positive clones correlated with increased serum levels of interferon gamma (IFNγ).

CONCLUSIONS

The presence of GRP78-positive clones in certain PBMC subpopulations in pCR patients suggests a dynamic interaction between ER stress and immune responsiveness. The correlation of GRP78-positive clones with increased levels of IFNγ supports the idea that GRP78 expression in PBMCs might serve as a new predictive marker to identify the possible benefits of taxanes in the neoadjuvant setting.

Contribution of the unfolded protein response to breast and prostate tissue homeostasis and its significance to cancer endocrine response

Resistant breast and prostate cancers remain a major clinical problem, new therapeutic approaches and better predictors of therapeutic response are clearly needed. Because of the involvement of the unfolded protein response (UPR) in cell proliferation and apoptosis evasion, an increasing number of publications support the hypothesis that impairments in this network trigger and/or exacerbate cancer. Moreover, UPR activation could contribute to the development of drug resistance phenotypes in both breast and prostate cancers. Therefore, targeting this pathway has recently emerged as a promising strategy in anticancer therapy. This review addresses the contribution of UPR to breast and prostate tissues homeostasis and its significance to cancer endocrine response with focus on the current progress on UPR research related to cancer biology, detection, prognosis and treatment.

Endoplasmic reticulum chaperone glucose-regulated protein 78 in gastric cancer: An emerging biomarker

The endoplasmic reticulum (ER) is the principal organelle responsible for the synthesis, initial post-translational modification, folding, export and secretion of proteins. It is also responsible for the maintenance of cellular homeostasis. In response to cellular stress conditions including glucose deprivation, hypoxia and changes in calcium homeostasis, ER stress machinery is activated and triggers the unfolded protein response, resulting in the restoration of homeostasis or activation of cell death. Glucose-regulated protein 78 (GRP78), a molecular chaperone, may be induced by ER stress at the transcriptional and translational level. A number of studies have demonstrated that GRP78 serves an important role in tumor cell proliferation, metastasis, angiogenesis and drug-resistance. The present review systematically describes the association between GRP78 expression and gastric cancer pathogenesis, and emphasizes that GRP78 is a novel diagnostic and therapeutic biomarker of gastric cancer.

FOXM1 promotes invasion and migration of colorectal cancer cells partially dependent on HSPA5 transactivation

In this study, to investigate whether endoplastic reticulum (ER) stress correlated with FOXM1 in colorectal cancer, we analysed the mRNA levels of FOXM1 and ER stress markers HSPA5 and spliced XBP1 by qRT-PCR. FOXM1 mRNA levels were found to positively correlate with HSPA5 in colorectal cancer. However, no significant correlation between FOXM1 and spliced XBP1 mRNA levels was found. Theses results suggested the positive correlation between FOXM1 and HSPA5 in colorectal cancer was not associated with ER stress. Next, we provided evidences that FOXM1 promoted HSPA5 transcription by directly binding to and stimulating HSPA5 promoter. Moreover, a FOXM1-binding site mapped between -1019 and -1012 bp of the proximal HSPA5 promoter was identified. In addition, we found that enhancement of cell migration and invasion by FOXM1 was significantly attenuated by depletion of HSPA5 in colorectal cancer cell. Furthermore, FOXM1 triggered colorectal cancer cell migration and invasion was involved in activities of cell-surface HSPA5. Lastly, our results suggested FOXM1 facilitated the activities and expressions of MMP2 and 9 associated with cell-surface HSPA5 in colorectal cancer cells. Moreover, statistically significant positive correlations between FOXM1 and MMP2 mRNA expression, between HSPA5 and MMP2 were found in colorectal cancer tissue specimens. Together, our results suggested that FOXM1-HSPA5 signaling might be considered as a novel molecular target for designing novel therapeutic regimen to control colorectal cancer metastasis and progression.

MiR-770 suppresses the chemo-resistance and metastasis of triple negative breast cancer via direct targeting of STMN1

Chemo-resistance and metastasis of triple negative breast cancer (TNBC) contributed the most of treatment failure in the clinic. MicroRNAs (miRNAs) have been proved to be involved in many biological processes and diseases. In this study, we aimed to determine the role of miR-770 in the regulation of chemo-resistance and metastasis of TNBC. Clinically, miR-770 was highly expressed in chemo-sensitive tissues and predicted a better prognosis of TNBC. Functionally, ectopic expression of miR-770 suppressed the doxorubicin-resistance of TNBC cell lines via regulation of apoptosis and tumor microenvironment, which was mediated by exosomes. Moreover, miR-770 overexpression inhibited the migration and invasion. Rescue of STMN1 could partly reverse the effect of miR-770 in TNBC behaviors. Furthermore, we also demonstrated that overexpression of miR-770 inhibited DOX resistance and metastasis in vivo. Taken together, our results proved that miR-770 could suppress the doxorubicin-resistance and metastasis of TNBC cells, which broaden our insights into the underlying mechanisms in chemo-resistance and metastasis, and provided a new prognostic marker for TNBC cells.

Enhanced expression of cell-surface B-cell receptor-associated protein 31 contributes to poor survival of non-small cell lung carcinoma cells

B-cell receptor-associated protein 31 (BAP31) is an endoplasmic reticulum (ER) membrane protein which plays a role as a molecular chaperone for the newly synthesized transmembrane proteins. BAP31 is also an important apoptosis regulator for extrinsic apoptosis induction in the ER membrane. Recent studies have shown that BAP31 is also expressed on the surface of embryonic stem cells. However, the function of cell surface BAP31 (csBAP31) still remains unclarified. In an attempt to search for surface markers on tumorspheres, here, we generated monoclonal antibodies (MAbs) against the sphere cells from the non-small cell lung carcinoma cell (NSCLC) line A549. SP1-B7, one of the MAbs, recognized csBAP31 whose expression was further increased on A549 sphere cells, as compared with A549 adherent cells. To investigate the role of csBAP31 in A549 cells, A549 adherent and sphere cells were stained with annexin V, propidium iodide, and SP1-B7. Interestingly, annexin V-high cells showed increased expression of csBAP31 as compared with annexin V-low cells. Caspase-3/7 activity was also increased in csBAP31-high cells as compared with csBAP31-low cells, suggesting that csBAP31-high cells are more sensitive to apoptosis. To further demonstrate the survival of csBAP31-positive A549 cells, csBAP31-positive and -negative A549 cells were sorted and subjected to the clonogenic survival assay. The colony number of csBAP31-positive A549 cells was decreased by approximately 1.7-fold, as compared that of csBAP31-negative A549 cells, suggesting that csBAP31-positve cells are sensitive to cell death indeed. The results suggest that enhanced expression of csBAP31 contributes to poor survival of NSCLC cells.

2-Deoxy-D-glucose Restore Glucocorticoid Sensitivity in Acute Lymphoblastic Leukemia via Modification of N-Linked Glycosylation in an Oxygen Tension-Independent Manner

In childhood acute lymphoblastic leukemia, treatment failure is associated with resistance to glucocorticoid agents. Resistance to this class of drugs represents one of the strongest indicators of poor clinical outcome. We show that leukemic cells, which are resistant to the glucocorticoid drug methylprednisolone, display a higher demand of glucose associated with a deregulation of metabolic pathways, in comparison to sensitive cells. Interestingly, a combinatorial treatment of glucocorticoid and the glucose analog 2-deoxy-D-glucose displayed a synergistic effect in methylprednisolone-resistant cells, in an oxygen tension-independent manner. Unlike solid tumors, where 2-deoxy-D-glucose promotes inhibition of glycolysis by hexokinase II exclusively under hypoxic conditions, we were able to show that the antileukemic effects of 2-deoxy-D-glucose are far more complex in leukemia. We demonstrate a hexokinase II-independent cell viability decrease and apoptosis induction of the glucose analog in leukemia. Additionally, due to the structural similarity of 2-deoxy-D-glucose with mannose, we could confirm that the mechanism by which 2-deoxy-D-glucose predominantly acts in leukemia is via modification in N-linked glycosylation, leading to endoplasmic reticulum stress and consequently induction of the unfolded protein response.

Taraxacum mongolicum extract induced endoplasmic reticulum stress associated-apoptosis in triple-negative breast cancer cells

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive and deadly breast cancer subtype with limited treatment options. It is necessary to seek complementary strategies for TNBC management. Taraxacum mongolicum, commonly named as dandelion, is a herb medicine with anti-cancer activity and has been utilized to treat mammary abscess, hyperplasia of mammary glands from ancient time in China, but the scientific evidence and action mechanisms still need to be studied.

AIM OF THE STUDY

This study was intended to investigate the therapeutic effect and molecular mechanisms of dandelion extract in TNBC cell line.

METHODOLOGY

Dandelion extract was prepared and purified, and then its chemical composition was determined. Cell viability was evaluated by MTT assay. Analysis of cell apoptosis and cell cycle was assessed by flow cytometry. The expression levels of mRNA and proteins were determined by real-time PCR and Western blotting, respectively. Caspase inhibitor Z-VAD-FMK and CHOP siRNA were used to confirm the cell apoptosis induced by dandelion extract.

RESULTS

Dandelion extract significantly decreased MDA-MB-231cell viability, triggered G2/M phase arrest and cell apoptosis. Concurrently, it caused a markedly increase of cleaved caspase-3 and PARP proteins. Caspase inhibitor Z-VAD-FMK abolished the apoptosis triggered by dandelion extract. The three ER stress-related signals were strongly induced after dandelion treatment, including increased mRNA expressions of ATF4, ATF6, XBP1s, GRP78 and CHOP genes, elevated protein levels of phosphorylated PERK, eIF-2α, IRE1, as well as the downstream molecules of CHOP and GRP78. MDA-MB-231 cells transfected with CHOP siRNA significantly reduced apoptosis induced by dandelion extract. The underlying mechanisms at least partially ascribe to the strong activation of PERK/p-eIF2α/ATF4/CHOP axis.

CONCLUSION

ER stress related cell apoptosis accounted for the anti-cancer effect of dandelion extract, and these findings support dandelion extract might be a potential therapeutic approach to treat TNBC.

TM7SF3, a novel p53-regulated homeostatic factor, attenuates cellular stress and the subsequent induction of the unfolded protein response

Earlier reported small interfering RNA (siRNA) high-throughput screens, identified seven-transmembrane superfamily member 3 (TM7SF3) as a novel inhibitor of pancreatic β-cell death. Here we show that TM7SF3 maintains protein homeostasis and promotes cell survival through attenuation of ER stress. Overexpression of TM7SF3 inhibits caspase 3/7 activation. In contrast, siRNA-mediated silencing of TM7SF3 accelerates ER stress and activation of the unfolded protein response (UPR). This involves inhibitory phosphorylation of eukaryotic translation initiation factor 2α activity and increased expression of activating transcription factor-3 (ATF3), ATF4 and C/EBP homologous protein, followed by induction of apoptosis. This process is observed both in human pancreatic islets and in a number of cell lines. Some of the effects of TM7SF3 silencing are evident both under basal conditions, in otherwise untreated cells, as well as under different stress conditions induced by thapsigargin, tunicamycin or a mixture of pro-inflammatory cytokines (tumor necrosis factor alpha, interleukin-1 beta and interferon gamma). Notably, TM7SF3 is a downstream target of p53: activation of p53 by Nutlin increases TM7SF3 expression in a time-dependent manner, although silencing of p53 abrogates this effect. Furthermore, p53 is found in physical association with the TM7SF3 promoter. Interestingly, silencing of TM7SF3 promotes p53 activity, suggesting the existence of a negative-feedback loop, whereby p53 promotes expression of TM7SF3 that acts to restrict p53 activity. Our findings implicate TM7SF3 as a novel p53-regulated pro-survival homeostatic factor that attenuates the development of cellular stress and the subsequent induction of the UPR.

Endocannabinoid system as a regulator of tumor cell malignancy - biological pathways and clinical significance

The endocannabinoid system (ECS) comprises cannabinoid receptors (CBs), endogenous cannabinoids, and enzymes responsible for their synthesis, transport, and degradation of (endo)cannabinoids. To date, two CBs, CB1 and CB2, have been characterized; however, orphan G-protein-coupled receptor GPR55 has been suggested to be the third putative CB. Several different types of cancer present abnormal expression of CBs, as well as other components of ECS, and this has been shown to correlate with the clinical outcome. Although most effects of (endo)cannabinoids are mediated through stimulation of classical CBs, they also interact with several molecules, either prosurvival or proapoptotic molecules. It should be noted that the mode of action of exogenous cannabinoids differs significantly from that of endocannabinoid and results from the studies on their activity both in vivo and in vitro could not be easily compared. This review highlights the main signaling pathways involved in the antitumor activity of cannabinoids and the influence of their activation on cancer cell biology. We also discuss changes in the expression pattern of the ECS in various cancer types that have an impact on disease progression and patient survival. A growing amount of experimental data imply possible exploitation of cannabinoids in cancer therapy.

Blocking heme oxygenase-1 by zinc protoporphyrin reduces tumor hypoxia-mediated VEGF release and inhibits tumor angiogenesis as a potential therapeutic agent against colorectal cancer

Background

Hypoxia in tumor niche is one of important factors to start regeneration of blood vessels, leading to increase survival, proliferation, and invasion in cancer cells. Under hypoxia microenvironment, furthermore, steadily increased hypoxia-inducible factor-1α (HIF-1α) is observed, and can increase vascular endothelial growth factor (VEGF) expression and promote angiogenesis. Zinc protoporphyrin (ZnPP), a heme oxygenase-1 (HO-1) inhibitor, is potential to inhibit tumor proliferation and progression. However, the mechanism of ZnPP in inhibition of tumor is not completely clear. We hypothesize that ZnPP may modulate HIF-1α through inhibiting HO-1, and then inhibit angiogenesis and tumor progression. This study aimed to dissect the mechanism of ZnPP in tumor suppression.

Results

We observed the amount of VEGF was increased in the sera of the colorectal cancer (CRC) patients (n = 34, p < 0.05). Furthermore, increased VEGF expression was also measured in colorectal cancer cells, HCT-15, culturing under mimicking hypoxic condition. It suggested that hypoxia induced VEGF production from cancer cells. VEGF production was significantly reduced from HCT-15 cells after exposure to HIF-1α inhibitor KC7F2, suggesting that HIF-1α regulated VEGF production. Moreover, we observed that the HO-1inhibitor ZnPP inhibited the expressions of HIF-1α and VEGF coupled with cell proliferations of HCT-15 cells, suggesting that ZnPP blocked HIF-1α expression, and then inhibited the consequent VEGF production. In the xenograft model, we also observed that the animals exposed to ZnPP displayed much smaller tumor nodules and less degree of angiogenesis with decreased expression of the angiogenesis marker, αvβ3 integrin, compared to that in normal control.

Conclusions

This study demonstrated that VEGF level in serum was elevated in the patients with CRC. The HO-1 inhibitor, ZnPP, possessed the properties of anti-tumor agent by decreasing HIF-1α levels, blocking VEGF production, impairing tumor angiogenesis, and inhibiting tumor growth.

Cell surface GRP78: A potential marker of good prognosis and response to chemotherapy in breast cancer

The 78-kDa glucose-regulated protein (GRP78) is a stress induced heat shock protein which, under limiting conditions, functions as a cell surface signaling receptor. Tumor cells are considered to be subjected to a physiologically stressful microenvironment due to their excessive growth. The role of GRP78 in tumor survival has been of notable interest. The present study aimed to assess the potential prognostic and predictive value of cell surface GRP78 expression in breast cancer tumor cells. Cell surface and cytoplasmic expression of GRP78 was examined by immunohistochemical staining of GRP78 in breast cancer archival paraffin-embedded tumor specimens. The cohort studied included breast cancer patients with operable T1,2, estrogen receptor-positive, node-negative cancer who were assessed using the Oncotype DX gene profile, as well as patients with locally advanced disease prior to and following neoadjuvant systemic treatment. GRP78 values were compared between the 2 groups, and prior to and following systemic treatment. Association analyses between GRP78 expression and prognostic markers were also performed. Cox regression analysis was used to examine the impact of these variables on disease-free survival (DFS). No differences in cytoplasmic GRP78 expression were observed. By contrast, the rates of cell surface GRP78 expression were 74.1% in the early stage operable patients, 36% in neoadjuvant systemic treatment patients prior to treatment and 62.5% in patients following systemic treatment (P<0.039). Positive cell surface GRP78 expression was associated with increased expression of the progesterone receptor (P=0.024), p53 expression (P=0.022) and improved DFS (P=0.047). In the case of GRP78 positivity, a trend for a superior response to chemotherapy was observed (P=0.19). The results of the present study indicated that cell surface GRP78 may be used as a marker for good prognosis in breast cancer and a potential marker for response to chemotherapy.