Inhibition of HSP90 overcomes resistance to chemotherapy and radiotherapy in pancreatic cancer

Synthesis and characterization of 64Cu-labeled Geldanamycin derivative for imaging HSP90 expression in breast cancer

Heat shock protein 90 (HSP90) plays a crucial role in cancer cell growth and metastasis by stabilizing overexpressed signaling proteins. Inhibiting HSP90 has emerged as a promising anti-cancer strategy. In this study, we aimed to develop and characterize a HSP90-targeted molecular imaging probe, [64Cu]Cu-DOTA-BDA-GM, based on a specific HSP90 inhibitor, geldanamycin (GM), for PET imaging of cancers. GM is modified at the C-17 position with 1,4-butane-diamine (BDA) and linked to 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) for 64Cu radiolabeling. We evaluated the probe's specific binding to HSP90-expressing cells using Chinese hamster ovary (CHO) cells and breast cancer cells including MDA-MB-231, MDA-MB-435S, MCF7, and KR-BR-3 cell lines. A competition study with non-radioactive GM-BDA yielded an IC50 value of 1.35 ± 0.14 nM, underscoring the probe's affinity for HSP90. In xenograft models of MDA-MB-231 breast cancer, [64Cu]Cu-DOTA-BDA-GM showcased targeted tumor localization, with significant radioactivity observed up to 18 h post-injection. Blocking studies using unlabeled GM-BDA and treatment with the anticancer drug Vorinostat (SAHA), which can affect the expression and activity of numerous proteins, such as HSPs, confirmed the specificity and sensitivity of the probe in cancer targeting. Additionally, PET/CT imaging in a lung metastasis mouse model revealed increased lung uptake of [64Cu]Cu-DOTA-BDA-GM in metastatic sites, significantly higher than in non-metastatic lungs, illustrating the probe's ability to detect metastatic breast cancer. In conclusion, [64Cu]Cu-DOTA-BDA-GM represents a sensitive and specific approach for identifying HSP90 expression in breast cancer and metastases, offering promising implications for clinical diagnosis and monitoring.

Combination therapy involving HSP90 inhibitors for combating cancer: an overview of clinical and preclinical progress

The molecular chaperone heat shock protein 90 (HSP90) regulates multiple crucial signalling pathways in cancer by driving the maturation of key signalling components, thereby playing a crucial role in tumorigenesis and drug resistance in cancer. Inhibition of HSP90 results in metastable conformational collapse of its client proteins and their proteasomal degradation. Considerable efforts have been devoted to the development of small-molecule inhibitors targeting HSP90, and more than 20 inhibitors have been evaluated in clinical trials for cancer therapy. However, owing to disadvantages such as organ toxicity and drug resistance, only one HSP90 inhibitor has been approved for use in clinical settings. In recent years, HSP90 inhibitors used in combination with other anti-cancer therapies have shown remarkable potential in the treatment of cancer. HSP90 inhibitors work synergistically with various anti-cancer therapies, including chemotherapy, targeted therapy, radiation therapy and immunotherapy. HSP90 inhibitors can improve the pharmacological effects of the above-mentioned therapies and reduce treatment resistance. This review provides an overview of the use of combination therapy with HSP90 inhibitors and other anti-cancer therapies in clinical and preclinical studies reported in the past decade and summarises design strategies and prospects for these combination therapies. Altogether, this review provides a theoretical basis for further research and application of these combination therapies in the treatment of cancer.

Heat Shock Proteins, a Double-Edged Sword: Significance in Cancer Progression, Chemotherapy Resistance and Novel Therapeutic Perspectives

Heat shock proteins (Hsps) are involved in one of the adaptive mechanisms protecting cells against environmental and metabolic stress. Moreover, the large role of these proteins in the carcinogenesis process, as well as in chemoresistance, was noticed. This review aims to draw attention to the possibilities of using Hsps in developing new cancer therapy methods, as well as to indicate directions for future research on this topic. In order to discuss this matter, a thorough review of the latest scientific literature was carried out, taking into account the importance of selected proteins from the Hsp family, including Hsp27, Hsp40, Hsp60, Hsp70, Hsp90 and Hsp110. One of the more characteristic features of all Hsps is that they play a multifaceted role in cancer progression, which makes them an obvious target for modern anticancer therapy. Some researchers emphasize the importance of directly inhibiting the action of these proteins. In turn, others point to their possible use in the design of cancer vaccines, which would work by inducing an immune response in various types of cancer. Due to these possibilities, it is believed that the use of Hsps may contribute to the progress of oncoimmunology, and thus help in the development of modern anticancer therapies, which would be characterized by higher effectiveness and lower toxicity to the patients.

The therapeutic effects of exosomes the first time isolated from pancreatic islet-derived progenitor cells in the treatment of pancreatic cancer

Insulinoma is an excessive insulin-released beta cell tumor. Pancreas cancer is one of the deadliest malignant neoplasms. Exosomes are secreted cell membrane vesicles containing a large number of proteins, lipids, and nucleic acids. The aim of this study is to investigate the effects of exosomes on two cell lines of benign and malignant character. For the first time, exosomes were isolated from pancreatic island-derived progenitor cells (PID-PCs) and applied to INS-1 and MiaPaCa-2 cells. In addition, exosomes isolated from PID-PC, MiaPaca-2, and INS-1 cells were characterized in order to compare their sizes with other previously isolated exosomes. Alix, TSG101, CD9, and CD81 were analyzed. The size and concentration of exosomes and the cell viability were detected. The cells were marked with HSP90, HSF-1, Kaspaz-8, Active-Kaspaz-3, Beclin, and p-Bcl-2. The cell cytotoxicity and insulin levels kit were measured. Alix in all exosomes, and PID-PC, MiaPaca-2 cell lysates; TSG101 in PID-PC and MiaPaca-2 cell lysates; CD9 in INS-1 exosomes were detected. The dimensions of isolated exosomes were 103.6 ± 28.6 nm, 100.7 ± 10 nm, and 147.2 ± 12.3 nm for PID-PCs, MiaPaca-2, and INS-1 cells. The cell viability decreased and HSP90 increased in the MiaPaca-2 cells. The HSF-1 was higher in the control MiaPaca-2 cell compared to the control INS-1 cell, and the exosome-treated MiaPaca-2 cell compared to the exosome-treated INS-1 cell. Beclin and p-Bcl-2 were decreased in the exosome-treated MiaPaca-2 cells. The insulin level in the cell lysates increased compared to cell secretion in INS-1 cells. In conclusion, exosomes isolated from the PID-PC caused cell death in the MiaPaca-2 cells in a time- and dose-dependent manner. The IC50 value determined for MiaPaca-2 cells has no effect on cell viability in INS-1 cells, which best mimics pancreatic beta cells and can be used instead of healthy pancreatic beta cells. Isolated exosomes can kill cancer cells without damaging healthy cells.

Vav1-dependent Rac1 activation mediates hypoxia-induced gemcitabine resistance in pancreatic ductal adenocarcinoma cells through upregulation of HIF-1α expression

Hypoxia has been shown to induce gemcitabine (GEM) resistance in pancreatic ductal adenocarcinoma (PDAC) cells, however, the underlying mechanisms remain to be clarified. In the present study, we investigated whether activation of Vav1/Rac1/HIF-1α axis is responsible for hypoxia-induced GEM resistance in PDAC cells. Our results showed that Rac1 activation contributed to hypoxia-induced GEM resistance in PANC-1 cells. Hypoxia treatment led to an increased expression level of Vav1, which was responsible for Rac1 activation and GEM resistance in PDAC cells. Furthermore, Rac1 mediated hypoxia-induced GEM resistance by upregulating HIF-1α in PDAC cells. Taken together, these findings suggest that hypoxia induces GEM resistance in PDAC cells by activating the Vav1/Rac1/HIF-1α signaling pathway.

Pancreatic Ductal Adenocarcinoma: The Characteristics of Contrast-Enhanced Ultrasound Are Correlated with the Hypoxic Microenvironment

A hypoxic microenvironment is associated with an increased risk of metastasis, treatment resistance and poor prognosis of pancreatic ductal adenocarcinoma (PDAC). This study aimed to identify contrast-enhanced ultrasound (CEUS) characteristics that could predict the hypoxic microenvironment of PDAC. A total of 102 patients with surgically resected PDAC who underwent CEUS were included. CEUS qualitative and quantitative characteristics were analyzed. The expression of hypoxia-inducible factor-1α (HIF-1) and glucose transporter-1 (GLUT1) were demonstrated by immunohistochemistry. The associations between CEUS characteristics and the HIF-1α and GLUT1 expression of PDACs were evaluated. We found that HIF-1α-high PDACs and GLUT1-high PDACs had a larger tumor size and were more prone to lymph node metastasis. There was a significant positive linear correlation between the expression of HIF-1α and GLUT1. CEUS qualitative characteristics including completeness of enhancement and peak enhancement degree (PED) were related to the expression of HIF-1α and GLUT1. A logistic regression analysis showed that tumor size, lymph node metastasis, incomplete enhancement and iso-enhancement of PED were independent predictors for HIF-1α-high PDACs and GLUT1-high PDACs. As for quantitative characteristics, HIF-1α-high PDACs and GLUT1-high PDACs showed higher peak enhancement (PE) and wash-in rate (WIR). CEUS can effectively reflect the hypoxia microenvironment of PDAC, which may become a noninvasive imaging biomarker for prognosis prediction and individualized treatment.

Gemcitabine effects on tumor microenvironment of pancreatic ductal adenocarcinoma: Special focus on resistance mechanisms and metronomic therapies

Pancreatic ductal adenocarcinoma (PDAC) is considered one of the deadliest malignancies, with dismal survival rates and extremely prevalent chemoresistance. Gemcitabine is one of the primary treatments used in treating PDACs, but its benefits are limited due to chemoresistance, which could be attributed to interactions between the tumor microenvironment (TME) and intracellular processes. In preclinical models, certain schedules of administration of gemcitabine modulate the TME in a manner that does not promote resistance. Metronomic therapy constitutes a promising strategy to overcome some barriers associated with current PDAC treatments. This review will focus on gemcitabine's mechanism in treating PDAC, combination therapies, gemcitabine's interactions with the TME, and gemcitabine in metronomic therapies.

Role of SIRT1 in Chemoresistant Leukemia

Leukemias of the AML, CML, and CLL types are the most common blood cancers worldwide, making them a major global public health problem. Furthermore, less than 24% of patients treated with conventional chemotherapy (low-risk patients) and 10-15% of patients ineligible for conventional chemotherapy (high-risk patients) survive five years. The low levels of survival are mainly due to toxicity and resistance to chemotherapy or other medication, the latter leading to relapse of the disease, which is the main obstacle to the treatment of leukemia. Drug resistance may include different molecular mechanisms, among which epigenetic regulators are involved. Silent information regulator 2 homolog 1 (SIRT1) is an epigenetic factor belonging to the sirtuin (SIRT) family known to regulate aspects of chromatin biology, genome stability, and metabolism, both in homeostasis processes and in different diseases, including cancer. The regulatory functions of SIRT1 in different biological processes and molecular pathways are dependent on the type and stage of the neoplasia; thus, it may act as both an oncogenic and tumor suppressor factor and may also participate in drug resistance. In this review, we explore the role of SIRT1 in drug-resistant leukemia and its potential as a therapeutic target.

Functional roles of SRC signaling in pancreatic cancer: Recent insights provide novel therapeutic opportunities

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignant disease with a 5-year survival rate of <10%. Aberrant activation or elevated expression of the tyrosine kinase c-SRC (SRC) is frequently observed in PDAC and is associated with a poor prognosis. Preclinical studies have revealed a multifaceted role for SRC activation in PDAC, including promoting chronic inflammation, tumor cell proliferation and survival, cancer cell stemness, desmoplasia, hypoxia, angiogenesis, invasion, metastasis, and drug resistance. Strategies to inhibit SRC signaling include suppressing its catalytic activity, inhibiting protein stability, or by interfering with signaling components of the SRC signaling pathway including suppressing protein interactions of SRC. In this review, we discuss the molecular and immunological mechanisms by which aberrant SRC activity promotes PDAC tumorigenesis. We also provide a comprehensive update of SRC inhibitors in the clinic, and discuss the clinical challenges associated with targeting SRC in pancreatic cancer.

Smart Nanofiber Mesh with Locally Sustained Drug Release Enabled Synergistic Combination Therapy for Glioblastoma

This study aims to propose a new treatment model for glioblastoma (GBM). The combination of chemotherapy, molecular targeted therapy and radiotherapy has been achieved in a highly simultaneous manner through the application of a safe, non-toxic, locally sustained drug-releasing composite Nanofiber mesh (NFM). The NFM consisted of biodegradable poly(ε-caprolactone) with temozolomide (TMZ) and 17-allylamino-17-demethoxygeldanamycin (17AAG), which was used in radiation treatment. TMZ and 17AAG combination showed a synergistic cytotoxicity effect in the T98G cell model. TMZ and 17AAG induced a radiation-sensitization effect, respectively. The NFM containing 17AAG or TMZ, known as 17AAG-NFM and TMZ-NFM, enabled cumulative drug release of 34.1% and 39.7% within 35 days. Moreover, 17AAG+TMZ-NFM containing both drugs revealed a synergistic effect in relation to the NFM of a single agent. When combined with radiation, 17AAG+TMZ-NFM induced in an extremely powerful cytotoxic effect. These results confirmed the application of NFM can simultaneously allow multiple treatments to T98G cells. Each modality achieved a significant synergistic effect with the other, leading to a cascading amplification of the therapeutic effect. Due to the superior advantage of sustained drug release over a long period of time, NFM has the promise of clinically addressing the challenge of high recurrence of GBM post-operatively.

FOXO3a-dependent up-regulation of HSP90 alleviates cisplatin-induced apoptosis by activating FUNDC1-mediated mitophagy in hypoxic osteosarcoma cells

Hypoxia-induced decrease in cisplatin (CDDP) sensitivity in human osteosarcoma (OS) is a significant obstacle to effective chemotherapy. Recently, mitophagy has been shown to be associated with CDDP sensitivity. However, whether it regulates hypoxia-induced decreases in CDDP sensitivity in OS and the underlying mechanisms remain unknown. In this study, we found that hypoxia activated mitophagy and suppressed mitophagy with specific inhibitors, mitochondrial division inhibitor-1 (Mdivi-1) or lysosome inhibitor chloroquine (CQ), which inhibited CDDP-induced apoptosis in hypoxic U-2OS and MG-63 cells. In addition, hypoxia upregulated the phosphorylation level of FUN14 domain-containing protein 1 (FUNDC1), whereas the activation of mitophagy and decreased CDDP sensitivity were inhibited by transfection with FUNDC1 small interfering RNA (siRNA). Hypoxia treatment also led to the up-regulation of heat shock protein 90 (HSP90), whereas HSP90 siRNA inhibited FUNDC1-mediated activation of mitophagy and decreased CDDP sensitivity. Furthermore, activation of Unc-51 like autophagy activating kinase 1 (Ulk1) was found in U-2OS and MG-63 cells after induction of hypoxia. Overexpression of Ulk1 prevented the inhibitory effect of HSP90 siRNA on the activation of FUNDC1 and mitophagy and decreased CDDP sensitivity in hypoxic U-2OS and MG-63 cells. Finally, hypoxia induced the activation of forkhead box transcription factor 3a (FOXO3a), whereas FOXO3a siRNA inhibited hypoxia-induced HSP90 up-regulation, Ulk1 activation, and FUNDC1-mediated activation of mitophagy, and decreased CDDP sensitivity in U-2OS and MG-63 cells. Using a chromatin immunoprecipitation (ChIP) assay, we confirmed that FOXO3a binds to the HSP90 promoter region. In conclusion, our findings suggest that hypoxia alleviates CDDP-induced apoptosis by activating mitophagy through the FOXO3a/HSP90/Ulk1/FUNDC1 signaling pathway in OS cells.

BTN3A1 promotes tumor progression and radiation resistance in esophageal squamous cell carcinoma by regulating ULK1-mediated autophagy

Radiotherapy is one of the most effective treatments for esophageal squamous cell carcinoma (ESCC); however, radioresistance is a clinical problem that must urgently be solved. Here, we found that butyrophilin subfamily 3 member A1 (BTN3A1) is upregulated in ESCC tumor tissues compared with nontumor tissues. We also evaluated BTN3A1 expression in patients with ESCC receiving adjuvant radiotherapy. The results demonstrated that BTN3A1 upregulation predicts a poor prognosis for ESCC patients. BTN3A1 overexpression promotes ESCC cell proliferation in vitro and in vivo. Moreover, BTN3A1 knockdown sensitized ESCC cells to radiation. We further explored the mode of death involved in BTN3A1-mediated radioresistance. Previous studies have shown that apoptosis, autophagy, necrosis, pyroptosis and ferroptosis are important for the survival of ESCC cells. We performed an RT-PCR array and western blotting (WB) to identify the mode of death and revealed for the first time that BTN3A1 promotes cell radioresistance by activating autophagy. In addition, by performing immunoprecipitation and mass spectrometry analyses, we found that BTN3A1 regulated the expression of UNC-51-like autophagy activating kinase 1(ULK1) and promoted its phosphorylation to subsequently initiate autophagy. Chromatin immunoprecipitation (ChIP) and luciferase reporter assay results indicated that BTN3A1 is a novel direct target of hypoxia inducible factor-1α (HIF-1α). HIF-1α, a transcription factor, promotes BTN3A1 transcription upon irradiation. Overall, the present study is the first to show that BTN3A1 plays a key role in radioresistance and that targeting BTN3A1 might be a promising strategy to improve radiotherapy efficacy in patients with ESCC.

Evaluation of the Heat Shock Protein 90 Inhibitor Ganetespib as a Sensitizer to Hyperthermia-Based Cancer Treatments

Simple Summary

Hyperthermia boosts the effects of radio- and chemotherapy regimens, but its clinical potential is hindered by the ability of (cancer) cells to activate a protective mechanism known as the heat stress response. Strategies that inhibit its activation or functions have the potential, therefore, to improve the overall efficacy of hyperthermia-based treatments. In this study, we evaluated the efficacy of the HSP90 inhibitor ganetespib in promoting the effects of radiotherapy or cisplatin combined with hyperthermia in vitro and in a cervix cancer mouse model.

Abstract

Hyperthermia is being used as a radio- and chemotherapy sensitizer for a growing range of tumor subtypes in the clinic. Its potential is limited, however, by the ability of cancer cells to activate a protective mechanism known as the heat stress response (HSR). The HSR is marked by the rapid overexpression of molecular chaperones, and recent advances in drug development make their inhibition an attractive option to improve the efficacy of hyperthermia-based therapies. Our previous in vitro work showed that a single, short co-treatment with a HSR (HSP90) inhibitor ganetespib prolongs and potentiates the effects of hyperthermia on DNA repair, enhances hyperthermic sensitization to radio- and chemotherapeutic agents, and reduces thermotolerance. In the current study, we first validated these results using an extended panel of cell lines and more robust methodology. Next, we examined the effects of hyperthermia and ganetespib on global proteome changes. Finally, we evaluated the potential of ganetespib to boost the efficacy of thermo-chemotherapy and thermo-radiotherapy in a xenograft murine model of cervix cancer. Our results revealed new insights into the effects of HSR inhibition on cellular responses to heat and show that ganetespib could be employed to increase the efficacy of hyperthermia when combined with radiation.

Targeting Heat-Shock Protein 90 in Cancer: An Update on Combination Therapy

Heat-shock protein 90 (HSP90) is an important molecule chaperone associated with tumorigenesis and malignancy. HSP90 is involved in the folding and maturation of a wide range of oncogenic clients, including diverse kinases, transcription factors and oncogenic fusion proteins. Therefore, it could be argued that HSP90 facilitates the malignant behaviors of cancer cells, such as uncontrolled proliferation, chemo/radiotherapy resistance and immune evasion. The extensive associations between HSP90 and tumorigenesis indicate substantial therapeutic potential, and many HSP90 inhibitors have been developed. However, due to HSP90 inhibitor toxicity and limited efficiency, none have been approved for clinical use as single agents. Recent results suggest that combining HSP90 inhibitors with other anticancer therapies might be a more advisable strategy. This review illustrates the role of HSP90 in cancer biology and discusses the therapeutic value of Hsp90 inhibitors as complements to current anticancer therapies.

Relationship between heat shock proteins and cellular resistance to drugs and ageing

BACKGROUND AND AIMS

Ageing is a multifactorial degenerative process which causes a decrease in the cellular capacity for repair and adaptation to external stressors. In this way, it is important to maintain the proper balance of the proteome. Heat shock proteins (HSP) will intervene in this balance, which are responsible for the correct assembly, folding and translocation of other proteins when cells are subjected to stressors. This type of protein is overexpressed in human tumor cells, while its deficit, both in function and quantity, contributes to ageing processes. The present work aims to analyze the response of cells from studies carried out in normal and tumor cells that are subjected to stressors.

METHODS AND RESULTS

A PubMed search was performed using the keywords "cell ageing, cell longevity, resistance, HSP, heat shock proteins, thermal shock proteins". This search generated 212 articles. Subsequently, a series of inclusion and exclusion criteria were applied to select the articles of interest to be evaluated. Normal cells subjected to external stressors at low doses increase the number of HSP, causing them to become more resistant. In addition, tumor cells expressing high levels of HSP show greater resistance to treatment and increased cell replication. HSP intervene in the cellular resistance of both normal and tumor cells.

CONCLUSIONS

In the case of normal cells, the increase in HSP levels makes them respond effectively to an external stressor, increasing their resistance and not causing cell death. In the case of tumor cells, there is an increase in resistance to treatment.

Neoadjuvant Therapy for Pancreatic Ductal Adenocarcinoma: Where Do We Go?

The incidence of pancreatic ductal adenocarcinoma (PDAC) has been on the rise in recent years; however, its clinical diagnosis and treatment remain challenging. Although surgical resection remains the only chance for long-term patient survival, the likelihood of initial resectability is no higher than 20%. Neoadjuvant therapy (NAT) in PDAC aims to transform the proportion of inoperable PDACs into operable cases and reduce the likelihood of recurrence to improve overall survival. Ongoing phase 3 clinical trial aims to validate the role of NAT in PDAC therapy, including prolongation of survival, increased R0 resection, and a higher proportion of negative lymph nodes. Controversies surrounding the role of NAT in PDAC treatment include applicability to different stages of PDAC, chemotherapy regimens, radiation, duration of treatment, and assessment of effect. This review aims to summarize the current progress and controversies of NAT in PDAC.

Exploration of the System-Level Mechanisms of the Herbal Drug FDY003 for Pancreatic Cancer Treatment: A Network Pharmacological Investigation

Pancreatic cancer (PC) is the most lethal cancer with the lowest survival rate globally. Although the prescription of herbal drugs against PC is gaining increasing attention, their polypharmacological therapeutic mechanisms are yet to be fully understood. Based on network pharmacology, we explored the anti-PC properties and system-level mechanisms of the herbal drug FDY003. FDY003 decreased the viability of human PC cells and strengthened their chemosensitivity. Network pharmacological analysis of FDY003 indicated the presence of 16 active phytochemical components and 123 PC-related pharmacological targets. Functional enrichment analysis revealed that the PC-related targets of FDY003 participate in the regulation of cell growth and proliferation, cell cycle process, cell survival, and cell death. In addition, FDY003 was shown to target diverse key pathways associated with PC pathophysiology, namely, the PIK3-Akt, MAPK, FoxO, focal adhesion, TNF, p53, HIF-1, and Ras pathways. Our network pharmacological findings advance the mechanistic understanding of the anti-PC properties of FDY003 from a system perspective.

Relationship between HSP90 protein expression and overall survival and clinicopathological outcomes in gastric cancer patients

Aim Gastric cancer is a highly prevalent public health problem with high morbidity and mortality. İt’s primary treatment is surgery. Recently studies involving biological parameters and genetics in gastric cancer are emerging but with many blind spots Our study aims to investigate the clinicopathological and prognostic significance of heat shock proteins (HSP90) expression in patients with resectable gastric cancer. Methods One center retrospective clinical study conducted at general surgery clinic at in a local training and research hospital. Our study involves 54 patients who had curative surgery for gastric cancer between 2011 and 2014. Results Pathological specimens fixed in formaline and parafin were re-evaluated with HSP90 stain and expression of HSP90 was evaluated. It was seen that only 39 (72.2%) patients had HSP90 expression. Seventeen (31.5%) of these had mild, 13 (24.1%) had moderate, 9 (10.5%) severe expression. Conclusion There are various reports in literature about HSP90 expression in gastric cancer which state that it is a prognosticator while some studies say it is not. There are a number of shortcomings of our study as we did not include metastatic tumors, study involves only our patients, low number of patients, single pathologist involvement. This is the first study done in our population on this subject. Further studies could be done to delineate this particular relationship in an effort to possibly identify novel treatments in gastric cancer.

Identify potential prognostic indicators and tumor-infiltrating immune cells in pancreatic adenocarcinoma

Background: Pancreatic adenocarcinoma (PAAD) is a kind of highly malignant tumor and lacks early diagnosis method and effective treatment. Tumor microenvironment (TME) is of great importance for the occurrence and development of PAAD. Thus, a comprehensive overview of genes and tumor-infiltrating immune cells (TICs) related to TME dynamic changes conduce to develop novel therapeutic targets and prognostic indicators.

Methods: We used MAlignant Tumors using Expression data (ESTIMATE) algorithm to analyze the transcriptome RNA-seq data of 182 PAAD cases on The Cancer Genome Atlas (TCGA) platform. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), protein–protein interaction (PPI) network, COX regression analysis and gene set enrichment analysis (GSEA) were carried out to get the hub genes related to the prognosis of PAAD patients. These core genes were validated in GEPIA. CXCL10 expression as a poor prognostic indicator was validated in GEO database. Finally, CIBERSORT algorithm was applied to understand the status of TICs.

Results: A total of 715 up-regulated differential expression genes (DEGs) and 57 down-regulated DEGs were found simultaneously in stromal and immune groups. These DEGs were mainly enriched in immune recognition, activation and response processes. CD4, CXCL12, CXCL10, CCL5 and CXCL9 were the top five core genes. Then, the validation of these genes showed that CD4, CXCL10, CXCL5, CXCL9 were up-regulated in PAAD. Among the core genes, CXCL10 had a negative correlation with the survival time of PAAD patients. CD8+ T cells, CD4+ T cells memory activated, macrophages M1 had positive correlation of CXCL10 expression, whereas regulatory T cells (Tregs), macrophages M0 and B cells memory had negative correlation.

Conclusion: We generated a series of genes related to TME with prognostic implications and TICs in PAAD, which have the potential to be novel immunotherapy targets and prognostic markers. The data showed that CXCL10 was favorable as a poor prognostic indicator in PAAD patients.

HSP90 promotes radioresistance of cervical cancer cells via reducing FBXO6 mediated CD147 polyubiquitination

HSP90 inhibition might be a promising strategy to overcome the radioresistance of some cancers. In the current study, we further explored the mechanisms of HSP90 in regulating the radiosensitivity of cervical cancer cells. Bioinformatic analysis was performed based on data from TCGA‐CESC. Cellular and molecular studies were conducted using CaSki and SiHa and the derived radioresistant (RR) subclones. Through a proteomics screen, we identified HSP90 chaperones (both HSP90α and HSP90β) as CD147‐binding partners supporting its stabilization. Targeting HSP90 sensitized CaSki‐RR and SiHa‐RR cancer cells to irradiation partially through CD147 destabilization. Mechanistically, HSP90 interacts with FBXO6 and reduces FBXO6‐mediated proteasomal degradation of CD147. Enforced FBXO6 overexpression also sensitized CaSki‐RR and SiHa‐RR cancer cells to irradiation. These effects were enhanced using 17‐AAG treatment but were weakened by CD147 overexpression. Survival analysis further confirmed the association between high FBXO6 expression and favorable progression‐free survival among patients with cervical cancer. In conclusion, this study showed that HSP90 promotes radioresistance of cervical cancer cells partially via reducing FBXO6 mediated CD147 polyubiquitination. These findings help to explain why HSP90 inhibitor exerts radio‐sensitizing effects in cervical cancer.

Enhancing the Therapeutic Efficacy of KRASG12C Inhibitors in Lung Adenocarcinoma Cell Models by Cotargeting the MAPK Pathway or HSP90

Background

KRAS^G12C inhibitors have shown promising efficacy in early clinical trials, but drug resistance compromises their long-term benefits. Therefore, it is critical to understand the mechanisms of drug resistance and to design appropriate combinatory treatments to improve efficacy.

Methods

To understand the comprehensive mechanisms of drug resistance, we treated lung cancer cells with KRAS^G12C inhibitors for different periods and performed transcriptional profiling and signaling analysis to identify critical factors and pathways that drive drug tolerance and resistance. We also evaluated several drug combinations in vitro and in vivo to identify potentially effective therapeutics.

Results

We found that the feedback activation of multiple receptor tyrosine kinases (RTKs) may have cooperatively induced intrinsic and adaptive resistance to KRAS^G12C inhibitors. Notably, continuous KRAS inhibition induced a multidrug-resistant phenotype, implying that upfront combinatory treatment might be required to treat this group of patients. We also demonstrated that concurrently targeting multiple nodes in the RTK/RAS/RAF/MEK/ERK axis improved the efficacy of KRAS^G12C inhibitors, mainly by suppressing the reactivation of the mitogen-activated protein kinase (MAPK) pathway. Moreover, the combined use of HSP90 and KRAS^G12C inhibitors effectively induced tumor regression in lung adenocarcinoma models in vitro and in vivo.

Conclusion

Together, our findings revealed mechanisms underlying KRAS^G12C inhibitors resistance and provided novel candidate combinatory strategies to improve their anticancer activity.

Extracellular vesicles and immunogenic stress in cancer

Tumor progression requires bidirectional cell-to-cell communication within a complex tumor microenvironment (TME). Extracellular vesicles (EVs) as carriers have the capacity to shuttle regulatory molecules, including nucleic acids, proteins, and lipids, between cancer cells and multiple stromal cells, inducing remarkable phenotypic alterations in the TME. Recently proposed the concept “immunogenic stress”, which means in some stressed microenvironment, cancer cells can release EVs containing specific immunoregulatory mediators, depending on the initiating stress-associated pathway, thereby provoking the changes of immune status in the TME. Considerable evidence has revealed that the intracellular mechanisms underlying the response to diverse stresses are mainly autophagy, endoplasmic reticulum (ER) stress reactions and the DNA damage response (DDR). In addition, the activation of immunogenic stress responses endows hosts with immune surveillance capacity; in contrast, several cargoes in EVs under immunogenic stress trigger a passive immune response by mediating the function of immune cells. This review discusses the current understanding of the immunogenic stress pathways in cancer and describes the interrelation between EVs and immunogenic stress to propose potential treatment strategies and biomarkers.

Contemporary Perspectives on the Warburg Effect Inhibition in Cancer Therapy

In the 1920s, Otto Warburg observed the phenomenon of altered glucose metabolism in cancer cells. Although the initial hypothesis suggested that the alteration resulted from mitochondrial damage, multiple studies of the subject revealed a precise, multistage process rather than a random pattern. The phenomenon of aerobic glycolysis emerges not only from mitochondrial abnormalities common in cancer cells, but also results from metabolic reprogramming beneficial for their sustenance. The Warburg effect enables metabolic adaptation of cancer cells to grow and proliferate, simultaneously enabling their survival in hypoxic conditions. Altered glucose metabolism of cancer cells includes, inter alia, qualitative and quantitative changes within glucose transporters, enzymes of the glycolytic pathway, such as hexokinases and pyruvate kinase, hypoxia-inducible factor, monocarboxylate transporters, and lactate dehydrogenase. This review summarizes the current state of knowledge regarding inhibitors of cancer glucose metabolism with a focus on their clinical potential. The altered metabolic phenotype of cancer cells allows for targeting of specific mechanisms, which might improve conventional methods in anti-cancer therapy. However, several problems such as drug bioavailability, specificity, toxicity, the plasticity of cancer cells, and heterogeneity of cells in tumors have to be overcome when designing therapies based on compounds targeted in cancer cell energy metabolism.

Therapeutic targeting of STAT3 pathways in pancreatic adenocarcinoma: A systematic review of clinical and preclinical literature

BACKGROUND/OBJECTIVES

Pancreatic ductal adenocarcinoma is a highly lethal disease with increasing incidence. Due to high resistance, chemo/radiotherapy has limited success in pancreatic cancer and only marginally prolongs patient survival. Therefore, novel biomarkers and therapeutic targets are needed. In the present review, we performed a comprehensive summary of therapeutic approaches targeting the GP130/JAK/STAT3 pathway.

METHODS

We systematically reviewed the PubMed and Embase databases for preclinical and clinical studies, from inception to October 4, 2020, on drugs targeting the GP130/JAK/STAT3 pathway. Bias assessments and qualitative analyses were performed.

RESULTS

Twenty-five preclinical and nine clinical trials were included in the review. All preclinical studies reported a favorable outcome in terms of pancreatic ductal adenocarcinoma progression. Futhermore, drugs targeting the GP130/JAK/STAT3 pathway were shown to be efficient chemosensitizers. However, high publication bias was assumed. In the clinical setting, bazedoxifene and itacitinib improved patient outcomes.

CONCLUSION

Preclinical studies strongly suggest significant efficacy of drugs targeting GP130/JAK/STAT3 in the treatment of pancreatic ductal adenocarcinoma and that these molecules are effective chemosensitizers. Though only a few trials have shown the efficacy in a clinical setting, the STAT3 pathway remains a promising drug target for future treatment of pancreatic ductal adenocarcinoma and may help overcome chemotherapy resistance.

Heat Shock Protein 90 Inhibitor Effects on Pancreatic Cancer Cell Cultures

OBJECTIVES

Pancreatic ductal adenocarcinoma is one of the deadliest cancers for which few curative therapies are available to date. Heat shock protein 90 (Hsp90) inhibitors have shown activity against numerous cancers in vitro; therefore, we tested whether they could be used to target pancreatic ductal adenocarcinoma.

METHODS

Inhibitors of Hsp90 ATPase activity were applied on low-passage pancreatic cell line cultures (Panc10.05, Panc215, A6L) in a dose-response manner, and the inhibitor in vitro effect on cell growth was evaluated. Seven of novel Hsp90 inhibitors based on resorcinol fragment and 5 commercially available Hsp90 inhibitors (17-AAG, AT-13387, AUY-922, ganetespib, and rifabutin) as well as control compound triptolide were tested yielding IC50 values in 2- and 3-dimensional assays.

RESULTS

The novel Hsp90 inhibitors exhibited strong effects on all 3 tested pancreatic cell line cultures (Panc10.05, Panc215, A6L) reaching the IC50 of 300 to 600 nM in 2- and 3-dimensional assays.

CONCLUSIONS

Novel Hsp90 inhibitors can be developed as antipancreatic cancer agents. Their chemical structures are simpler, and they are likely to exhibit lower side effects than the much more complex inhibitors used as controls.

Single-cell RNA sequencing reveals that targeting HSP90 suppresses PDAC progression by restraining mitochondrial bioenergetics

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers, which lacks effective treatment strategies. There is an urgent need for the development of new strategies for PDAC therapy. The genetic and phenotypic heterogeneity of PDAC cancer cell populations poses further challenges in the clinical management of PDAC. In this study, we performed single-cell RNA sequencing to characterize PDAC tumors from KPC mice. Functional studies and clinical analysis showed that PDAC cluster 2 cells with highly Hsp90 expression is much more aggressive than the other clusters. Genetic and pharmacologic inhibition of Hsp90 impaired tumor cell growth both in vitro and in vivo. Further mechanistic study revealed that HSP90 inhibition disrupted the interaction between HSP90 and OPA1, leading to a reduction in mitochondrial cristae amount and mitochondrial energy production. Collectively, our study reveals that HSP90 might be a potential therapeutic target for PDAC.

The crosstalk between HIFs and mitochondrial dysfunctions in cancer development

Mitochondria are essential cellular organelles that are involved in regulating cellular energy, metabolism, survival, and proliferation. To some extent, cancer is a genetic and metabolic disease that is closely associated with mitochondrial dysfunction. Hypoxia-inducible factors (HIFs), which are major molecules that respond to hypoxia, play important roles in cancer development by participating in multiple processes, such as metabolism, proliferation, and angiogenesis. The Warburg phenomenon reflects a pseudo-hypoxic state that activates HIF-1α. In addition, a product of the Warburg effect, lactate, also induces HIF-1α. However, Warburg proposed that aerobic glycolysis occurs due to a defect in mitochondria. Moreover, both HIFs and mitochondrial dysfunction can lead to complex reprogramming of energy metabolism, including reduced mitochondrial oxidative metabolism, increased glucose uptake, and enhanced anaerobic glycolysis. Thus, there may be a connection between HIFs and mitochondrial dysfunction. In this review, we systematically discuss the crosstalk between HIFs and mitochondrial dysfunctions in cancer development. Above all, the stability and activity of HIFs are closely influenced by mitochondrial dysfunction related to tricarboxylic acid cycle, electron transport chain components, mitochondrial respiration, and mitochondrial-related proteins. Furthermore, activation of HIFs can lead to mitochondrial dysfunction by affecting multiple mitochondrial functions, including mitochondrial oxidative capacity, biogenesis, apoptosis, fission, and autophagy. In general, the regulation of tumorigenesis and development by HIFs and mitochondrial dysfunction are part of an extensive and cooperative network.

The PI3K/Akt/mTOR signaling pathway in gastric cancer; from oncogenic variations to the possibilities for pharmacologic interventions

Genetic and epigenetic alterations have been under concentrated investigations for many years in order to unearth the molecules regulating human cancer pathogenesis. However, the identification of a wide range of dysregulated genes and their protein products has raised a question regarding how the results of this large collection of alterations could converge into a formation of one malignancy. The answer may be found in the signaling cascades that regulate the survival and metabolism of the cells. Aberrancies of each participant molecule of such cascades may well result in augmented viability and unlimited proliferation of cancer cells. Among various signaling pathways, the phosphatidylinositol-3-kinase (PI3K) axis has been shown to be activated in about one-third of human cancers. One of the malignancies that is mostly affected by this axis is gastric cancer (GC), one of the most fatal cancers worldwide. In the present review, we aimed to illustrate the significance of the PI3K/Akt/mTOR axis in the pathogenesis of GC and also provided a wide perspective about the application of the inhibitors of this axis in the therapeutic strategies of this malignancy.

Targeting hypoxic tumor microenvironment in pancreatic cancer

Attributable to its late diagnosis, early metastasis, and poor prognosis, pancreatic cancer remains one of the most lethal diseases worldwide. Unlike other solid tumors, pancreatic cancer harbors ample stromal cells and abundant extracellular matrix but lacks vascularization, resulting in persistent and severe hypoxia within the tumor. Hypoxic microenvironment has extensive effects on biological behaviors or malignant phenotypes of pancreatic cancer, including metabolic reprogramming, cancer stemness, invasion and metastasis, and pathological angiogenesis, which synergistically contribute to development and therapeutic resistance of pancreatic cancer. Through various mechanisms including but not confined to maintenance of redox homeostasis, activation of autophagy, epigenetic regulation, and those induced by hypoxia-inducible factors, intratumoral hypoxia drives the above biological processes in pancreatic cancer. Recognizing the pivotal roles of hypoxia in pancreatic cancer progression and therapies, hypoxia-based antitumoral strategies have been continuously developed over the recent years, some of which have been applied in clinical trials to evaluate their efficacy and safety in combinatory therapies for patients with pancreatic cancer. In this review, we discuss the molecular mechanisms underlying hypoxia-induced aggressive and therapeutically resistant phenotypes in both pancreatic cancerous and stromal cells. Additionally, we focus more on innovative therapies targeting the tumor hypoxic microenvironment itself, which hold great potential to overcome the resistance to chemotherapy and radiotherapy and to enhance antitumor efficacy and reduce toxicity to normal tissues.

Heat Shock Protein-90 Inhibition Alters Activation of Pancreatic Stellate Cells and Enhances the Efficacy of PD-1 Blockade in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) has a prominent fibrotic stroma, which is a result of interactions between tumor, immune and pancreatic stellate cells (PSC), or cancer-associated fibroblasts (CAF). Targeting inflammatory pathways present within the stroma may improve access of effector immune cells to PDAC and response to immunotherapy. Heat shock protein-90 (Hsp90) is a chaperone protein and a versatile target in pancreatic cancer. Hsp90 regulates a diverse array of cellular processes of relevance to both the tumor and the immune system. However, to date the role of Hsp90 in PSC/CAF has not been explored in detail. We hypothesized that Hsp90 inhibition would limit inflammatory signals, thereby reprogramming the PDAC tumor microenvironment to enhance sensitivity to PD-1 blockade. Treatment of immortalized and primary patient PSC/CAF with the Hsp90 inhibitor XL888 decreased IL6, a key cytokine that orchestrates immune changes in PDAC at the transcript and protein level in vitro XL888 directly limited PSC/CAF growth and reduced Jak/STAT and MAPK signaling intermediates and alpha-SMA expression as determined via immunoblot. Combined therapy with XL888 and anti-PD-1 was efficacious in C57BL/6 mice bearing syngeneic subcutaneous (Panc02) or orthotopic (KPC-Luc) tumors. Tumors from mice treated with both XL888 and anti-PD-1 had a significantly increased CD8+ and CD4+ T-cell infiltrate and a unique transcriptional profile characterized by upregulation of genes associated with immune response and chemotaxis. These data demonstrate that Hsp90 inhibition directly affects PSC/CAF in vitro and enhances the efficacy of anti-PD-1 blockade in vivo.

Unbiased in vivo preclinical evaluation of anticancer drugs identifies effective therapy for the treatment of pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is typically diagnosed at an advanced stage, which limits surgical options and portends a dismal prognosis. Current oncologic PDAC therapies confer marginal benefit and, thus, a significant unmet clinical need exists for new therapeutic strategies. To identify effective PDAC therapies, we leveraged a syngeneic orthotopic PDAC transplant mouse model to perform a large-scale, in vivo screen of 16 single-agent and 41 two-drug targeted therapy combinations in mice. Among 57 drug conditions screened, combined inhibition of heat shock protein (Hsp)-90 and MEK was found to produce robust suppression of tumor growth, leading to an 80% increase in the survival of PDAC-bearing mice with no significant toxicity. Mechanistically, we observed that single-agent MEK inhibition led to compensatory activation of resistance pathways, including components of the PI3K/AKT/mTOR signaling axis, which was overcome with the addition of HSP90 inhibition. The combination of HSP90(i) + MEK(i) was also active in vitro in established human PDAC cell lines and in vivo in patient-derived organoid PDAC transplant models. These findings encourage the clinical development of HSP90(i) + MEK(i) combination therapy and highlight the power of clinically relevant in vivo model systems for identifying cancer therapies.

Therapeutic resistance of pancreatic cancer: Roadmap to its reversal

Pancreatic cancer is a lethal disease with limited opportunity for resectable surgery as the first choice for cure due to its late diagnosis and early metastasis. The desmoplastic stroma and cellular genetic or epigenetic alterations of pancreatic cancer impose physical and biological barriers to effective therapies, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy. Here, we review the current therapeutic options for pancreatic cancer, and underlying mechanisms and potential reversal of therapeutic resistance, a hallmark of this deadly disease.

HIF-1α and RKIP: a computational approach for pancreatic cancer therapy

Protein-protein interactions (PPIs) are important biochemical processes that represent a major challenge in modern biology. Current approaches, which include high-throughput screening and computer aided ligand design, have limitations regarding the identification of hit matter. This current investigation focuses on computational study for protein-protein docking of hypoxia inducible factor-1α (HIF-1α), a tumor inducible factor, and Raf-1 kinase inhibitory protein (RKIP), a tumor metastasis suppressor. These are individually crystallized structures of interacting proteins, which interact to generate a conformational space. HIF activity in pancreatic tumors is determined by hypoxia and HIF-1α subunit availability. RKIP can be used as a prognostic indicator in a number of tumors. The interaction of RKIP with HIF-1α protects against pancreatic cancer (PC) metastasis by inhibiting its hypoxia function. We have explored the binding affinity between both the proteins with the HADDOCK (high ambiguity driven protein-protein docking) server, which determined that 158 structures in 11 clusters represent 79.0% of water-refined models. Of the best 10 clusters, the structures of cluster 2 were found to be better, as they had the lowest Z-score. Further supporting HIF-1α-RKIP interaction, pulldown assay has shown dissociation of RKIP from HIF-1α after CoCl2 treatment in both PC cell lines.

Priming of Anti-tumor Immune Mechanisms by Radiotherapy Is Augmented by Inhibition of Heat Shock Protein 90

Radiotherapy is an essential part of multi-modal cancer therapy. Nevertheless, for certain cancer entities such as colorectal cancer (CRC) the indications of radiotherapy are limited due to anatomical peculiarities and high radiosensitivity of the surrounding normal tissue. The development of molecularly targeted, combined modality approaches may help to overcome these limitations. Preferably, such strategies should not only enhance radiation-induced tumor cell killing and the abrogation of tumor cell clonogenicity, but should also support the stimulation of anti-tumor immune mechanisms – a phenomenon which moved into the center of interest of preclinical and clinical research in radiation oncology within the last decade. The present study focuses on inhibition of heat shock protein 90 (HSP90) whose combination with radiotherapy has previously been reported to exhibit convincing therapeutic synergism in different preclinical cancer models. By employing in vitro and in vivo analyses, we examined if this therapeutic synergism also applies to the priming of anti-tumor immune mechanisms in model systems of CRC. Our results indicate that the combination of HSP90 inhibitor treatment and ionizing irradiation induced apoptosis in colorectal cancer cells with accelerated transit into secondary necrosis in a hyperactive Kras-dependent manner. During secondary necrosis, dying cancer cells released different classes of damage-associated molecular patterns (DAMPs) that stimulated migration and recruitment of monocytic cells in vitro and in vivo. Additionally, these dying cancer cell-derived DAMPs enforced the differentiation of a monocyte-derived antigen presenting cell (APC) phenotype which potently triggered the priming of allogeneic T cell responses in vitro. In summary, HSP90 inhibition – apart from its radiosensitizing potential – obviously enables and supports the initial steps of anti-tumor immune priming upon radiotherapy and thus represents a promising partner for combined modality approaches. The therapeutic performance of such strategies requires further in-depth analyses, especially for but not only limited to CRC.

Hypoxia: Friend or Foe for drug delivery in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal solid tumors with an overall five-year survival rate of that has only just reached 10%. The tumor microenvironment of PDAC is characterized by desmoplasia, which consist of dense stroma of fibroblasts and inflammatory cells, resulting in a hypoxic environment due to limited oxygen diffusion through the tumor. Hypoxia contributes to the aggressive tumor biology by promoting tumor progression, malignancy, and promoting resistance to conventional and targeted therapeutic agents. In depth research in the area has identified that hypoxia modulates the tumor biology through hypoxia inducible factors (HIFs), which not only are the key determinant of pancreatic malignancy but also an important target for therapy. In this review, we summarize the recent advances in understanding hypoxia driven phenotypes, which are responsible for the highly aggressive and metastatic characteristics of pancreatic cancer, and how hypoxia can be exploited as a target for drug delivery.

PTEN, a Barrier for Proliferation and Metastasis of Gastric Cancer Cells: From Molecular Pathways to Targeting and Regulation

Cancer is one of the life-threatening disorders that, in spite of excellent advances in medicine and technology, there is no effective cure for. Surgery, chemotherapy, and radiotherapy are extensively applied in cancer therapy, but their efficacy in eradication of cancer cells, suppressing metastasis, and improving overall survival of patients is low. This is due to uncontrolled proliferation of cancer cells and their high migratory ability. Finding molecular pathways involved in malignant behavior of cancer cells can pave the road to effective cancer therapy. In the present review, we focus on phosphatase and tensin homolog (PTEN) signaling as a tumor-suppressor molecular pathway in gastric cancer (GC). PTEN inhibits the PI3K/Akt pathway from interfering with the migration and growth of GC cells. Its activation leads to better survival of patients with GC. Different upstream mediators of PTEN in GC have been identified that can regulate PTEN in suppressing growth and invasion of GC cells, such as microRNAs, long non-coding RNAs, and circular RNAs. It seems that antitumor agents enhance the expression of PTEN in overcoming GC. This review focuses on aforementioned topics to provide a new insight into involvement of PTEN and its downstream and upstream mediators in GC. This will direct further studies for evaluation of novel signaling networks and their targeting for suppressing GC progression.

Hypoxia: a barricade to conquer the pancreatic cancer

Pancreatic cancer (PC) remains one of the most extremely lethal malignancies worldwide due to late diagnosis and early metastasis, with a 1-year overall survival rate of approximately 20%. The hypoxic microenvironment, induced by intratumoral hypoxia, promotes tumor invasion and progression, leading to chemotherapy or radiotherapy resistance and eventual mortality after treatment of PC. However, the role of the hypoxic microenvironment in PC is complicated and requires further investigation. In this article, we review recent advances regarding the regulation of malignant behaviors in PC, which provide insight into the potential of hypoxic microenvironment activation therapy for the therapeutic agents.

Melatonin as a Radio-Sensitizer in Cancer

Radiotherapy is one of the treatments of choice in many types of cancer. Adjuvant treatments to radiotherapy try, on one hand, to enhance the response of tumor cells to radiation and, on the other hand, to reduce the side effects to normal cells. Radiosensitizers are agents that increase the effect of radiation in tumor cells by trying not to increase side effects in normal tissues. Melatonin is a hormone produced mainly by the pineal gland which has an important role in the regulation of cancer growth, especially in hormone-dependent mammary tumors. Different studies have showed that melatonin administered with radiotherapy is able to enhance its therapeutic effects and can protect normal cells against side effects of this treatment. Several mechanisms are involved in the radiosensitization induced by melatonin: increase of reactive oxygen species production, modulation of proteins involved in estrogen biosynthesis, impairment of tumor cells to DNA repair, modulation of angiogenesis, abolition of inflammation, induction of apoptosis, stimulation of preadipocytes differentiation and modulation of metabolism. At this moment, there are very few clinical trials that study the therapeutic usefulness to associate melatonin and radiotherapy in humans. All findings point to melatonin as an effective adjuvant molecule to radiotherapy in cancer treatment.

Implications of HIF-1α in the tumorigenesis and progression of pancreatic cancer

Pancreatic cancer is one of the leading causes of cancer-related deaths worldwide and is characterized by highly hypoxic tumor microenvironment. Hypoxia-inducible factor-1 alpha (HIF-1α) is a major regulator of cellular response to changes in oxygen concentration, supporting the adaptation of tumor cells to hypoxia in an oxygen-deficient tumor microenvironment. Numerous studies revealed the central role of HIF-1α in the carcinogenesis and progression of pancreatic cancer. This article reviewed the molecular mechanisms of how HIF-1α regulated tumorigenesis and progression of pancreatic cancer and suggested that targeting HIF-1α and its signaling pathways could be promising therapeutics for pancreatic cancer.

The HSP90 inhibitor Onalespib exerts synergistic anti-cancer effects when combined with radiotherapy: an in vitro and in vivo approach

Oncogenic client-proteins of the chaperone Heat shock protein 90 (HSP90) insure unlimited tumor growth and are involved in resistance to chemo- and radiotherapy. The HSP90 inhibitor Onalespib initiates the degradation of oncoproteins, and might also act as a radiosensitizer. The aim of this study was therefore to evaluate the efficacy of Onalespib in combination with external beam radiotherapy in an in vitro and in vivo approach. Onalespib downregulated client proteins, lead to increased apoptosis and caused DNA-double-strands. Monotherapy and combination with radiotherapy reduced colony formation, proliferation and migration assessed in radiosensitive HCT116 and radioresistant A431 cells. In vivo, a minimal treatment regimen for 3 consecutive days of Onalespib (3 × 10 mg/kg) doubled survival, whereas Onalespib with radiotherapy (3 × 2 Gy) caused a substantial delay in tumor growth and prolonged the survival by a factor of 3 compared to the HCT116 xenografted control group. Our results demonstrate that Onalespib exerts synergistic anti-cancer effects when combined with radiotherapy, most prominent in the radiosensitive cell models. We speculate that the depletion and downregulation of client proteins involved in signalling, migration and DNA repair mechanisms is the cause. Thus, individually, or in combination with radiotherapy Onalespib inhibits tumor growth and has the potential to improve radiotherapy outcomes, prolonging the overall survival of cancer patients.

EFNB2 facilitates cell proliferation, migration, and invasion in pancreatic ductal adenocarcinoma via the p53/p21 pathway and EMT

Ephrin-2 (EFNB2) is expressed at abnormally high levels in some neoplasms, such as squamous cell carcinoma of the head and neck and colorectal cancer. Its overexpression is associated with the malignant progression of tumors. However, the expression of EFNB2 in pancreatic ductal adenocarcinoma (PDAC) has not been thoroughly studied. EFNB2 expression was evaluated by quantitative real-time PCR, immunohistochemistry, and western blotting. Furthermore, the association between its expression levels and the clinicopathological features of PDAC patients was explored. To determine the underlying mechanisms of EFNB2, we transfected PDAC cells with small interfering RNA and performed in vitro and in vivo experiments. EFNB2 expression levels were significantly increased in cancer tissues and were associated with PDAC clinical stage and Ki67 expression. The down-regulation of EFNB2 inhibited cell proliferation by up-regulating p53/p21-mediated G0/G1 phase blockade. Knockdown of EFNB2 decreased the migration and invasion of PDAC cells by blocking epithelial-mesenchymal transition. These results suggested that EFNB2 may participate in the development of PDAC by promoting cell proliferation, migration, and invasion. Thus, EFNB2 is a potential target for the diagnosis and treatment of PDAC.

Heat Shock Proteins: Agents of Cancer Development and Therapeutic Targets in Anti-Cancer Therapy

Heat shock proteins (HSPs) constitute a large family of molecular chaperones classified by their molecular weights, and they include HSP27, HSP40, HSP60, HSP70, and HSP90. HSPs function in diverse physiological and protective processes to assist in maintaining cellular homeostasis. In particular, HSPs participate in protein folding and maturation processes under diverse stressors such as heat shock, hypoxia, and degradation. Notably, HSPs also play essential roles across cancers as they are implicated in a variety of cancer-related activities such as cell proliferation, metastasis, and anti-cancer drug resistance. In this review, we comprehensively discuss the functions of HSPs in association with cancer initiation, progression, and metastasis and anti-cancer therapy resistance. Moreover, the potential utilization of HSPs to enhance the effects of chemo-, radio-, and immunotherapy is explored. Taken together, HSPs have multiple clinical usages as biomarkers for cancer diagnosis and prognosis as well as the potential therapeutic targets for anti-cancer treatment.

PADI3 plays an antitumor role via the Hsp90/CKS1 pathway in colon cancer

BACKGROUND

CKS1 is highly expressed in colon cancer tissues, and is essential for cancer cell proliferation. The downstream molecular mechanism of CKS1 has been fully studied, but the upstream regulatory mechanism of it is still unclear. Earlier research found that PADI3 plays its anti-tumor roles via suppress cell proliferation, in this study, we found that the expression pattern of PADI3 and CKS1 are negatively correlated in colon cancer tissues, and overexpression of PADI3 can partly reverse CKS1 induced cancer cell proliferation. However, the regulatory mechanism of PADI3 and CKS1 in the tumorigenesis of colon cancer is still unclear and need to do further research.

METHODS

Western blot and real-time PCR were used to detect the expression levels of genes. CCK-8 and colony formation assays were used to examine cell proliferation and colony formation ability. Overexpression and rescue experiments were used to study the molecular mechanism of CKS1 in colon cancer cells, BALB/c nude mice were used to study the function of CKS1 in vivo.

RESULTS

CKS1 is highly expressed in colon cancer tissues, and the overexpression of CKS1 promotes cell proliferation and colony formation in both HCT116 (originating from primary colon cancer) and SW620 (originating from metastatic tumor nodules of colon cancer) cells. CKS1-expressing HCT116 cells produced larger tumors than the control cells. The expression pattern of PADI3 and CKS1 are negatively correlation in clinical samples of colon cancer, further study indicates that PADI3 can significantly decrease Hsp90 and CKS1 expression, and Hsp90 is essential for PADI3 to downregulate CKS1expression in colon cancer cells.

CONCLUSIONS

PADI3 exerts its antitumor activity by inhibiting Hsp90 and CKS1 expression, and Hsp90 is essential for PADI3 to suppress CKS1 expression.