HSP90 inhibition downregulates thymidylate synthase and sensitizes colorectal cancer cell lines to the effect of 5FU-based chemotherapy

Integrated analysis reveals a novel 5-fluorouracil resistance-based prognostic signature with promising implications for predicting the efficacy of chemotherapy and immunotherapy in patients with colorectal cancer

BACKGROUND

5-Fluorouracil (5-FU) has been used as a standard first-line treatment for colorectal cancer (CRC) patients. Although 5-FU-based chemotherapy and immune checkpoint blockade (ICB) have achieved success in treating CRC, drug resistance and low response rates remain substantial limitations. Thus, it is necessary to construct a 5-FU resistance-related signature (5-FRSig) to predict patient prognosis and identify ideal patients for chemotherapy and immunotherapy.

METHODS

Using bulk and single-cell RNA sequencing data, we established and validated a novel 5-FRSig model using stepwise regression and multiple CRC cohorts and evaluated its associations with the prognosis, clinical features, immune status, immunotherapy, neoadjuvant therapy, and drug sensitivity of CRC patients through various bioinformatics algorithms. Unsupervised consensus clustering was performed to categorize the 5-FU resistance-related molecular subtypes of CRC. The expression levels of 5-FRSig, immune checkpoints, and immunoregulators were determined using quantitative real-time polymerase chain reaction (RT‒qPCR). Potential small-molecule agents were identified via Connectivity Map (CMap) and molecular docking.

RESULTS

The 5-FRSig and cluster were confirmed as independent prognostic factors in CRC, as patients in the low-risk group and Cluster 1 had a better prognosis. Notably, 5-FRSig was significantly associated with 5-FU sensitivity, chemotherapy response, immune cell infiltration, immunoreactivity phenotype, immunotherapy efficiency, and drug selection. We predicted 10 potential compounds that bind to the core targets of 5-FRSig with the highest affinity.

CONCLUSION

We developed a valid 5-FRSig to predict the prognosis, chemotherapeutic response, and immune status of CRC patients, thus optimizing the therapeutic benefits of chemotherapy combined with immunotherapy, which can facilitate the development of personalized treatments and novel molecular targeted therapies for patients with CRC.

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.

Competitive endogenous RNA networks: Decoding the role of long non-coding RNAs and circular RNAs in colorectal cancer chemoresistance

Colorectal cancer (CRC) is recognized as one of the most common gastrointestinal malignancies across the globe. Despite significant progress in designing novel treatments for CRC, there is a pressing need for more effective therapeutic approaches. Unfortunately, many patients undergoing chemotherapy develop drug resistance, posing a significant challenge for cancer treatment. Non-coding RNAs (ncRNAs) have been found to play crucial roles in CRC development and its response to chemotherapy. However, there are still gaps in our understanding of interactions among various ncRNAs, such as long non-coding RNAs (lncRNAs), circular RNAs (circRNAs) and microRNAs (miRNAs). These ncRNAs can act as either oncogenes or tumour suppressors, affecting numerous biological functions in different cancers including CRC. A class of ncRNA molecules known as competitive endogenous RNAs (ceRNAs) has emerged as a key player in various cellular processes. These molecules form networks through lncRNA/miRNA/mRNA and circRNA/miRNA/mRNA interactions. In CRC, dysregulation of ceRNA networks has been observed across various cellular processes, including proliferation, apoptosis and angiogenesis. These dysregulations are believed to play a significant role in the progression of CRC and, in certain instances, may contribute to the development of chemoresistance. Enriching our knowledge of these dysregulations holds promise for advancing the field of diagnostic and therapeutic modalities for CRC. In this review, we discuss lncRNA- and circRNA-associated ceRNA networks implicated in the emergence and advancement of drug resistance in colorectal carcinogenesis.

LncRNA NNT-AS1/hsa-miR-485-5p/HSP90 axis in-silico and clinical prospect correlated-to histologic grades-based CRC stratification: A step toward ncRNA Precision

The oncogenic effects of long non-coding RNA (lncRNA) Nicotinamide Nucleotide Transhydrogenase-antisense RNA1 (NNT-AS1) role in colorectal cancer (CRC) hasn't been sufficiently inspected in relation to the Homo sapiens (hsa)-microRNA (miR)- 485-5p/ heat shock protein 90 (HSP90) axis, clinically. qRT-PCR was performed to detect lncRNA NNT-AS1 and hsa-miR-485-5p expression levels in 60 Egyptian patients' sera. HSP90 serum level was quantified using Enzyme-linked immunosorbent assay (ELISA). The relative expression level of the studied non-coding RNAs as well as the HSP90 ELISA concentration were correlated with patients clinicopathological characteristics and correlated to each other. The axis diagnostic utility in comparison with carbohydrate antigen 19-9 (CA19-9) and carcinoembryonic antigen (CEA) tumor markers (TMs) was studied by receiver operating characteristic (ROC) curve analysis. The relative lncRNA NNT-AS1 expression level fold change 56.7 (13.5-112) and HSP90 protein ELISA level 6.68 (5.14-8.77) (ng/mL) were elevated, while, for hsa-miR-485-5p 0.0474 (0.0236-0.135) expression fold change was repressed in CRC Egyptian patients' cohort sera, being compared to 28 apparently healthy control subjects. LncRNA NNT-AS1 specificity is 96.4% and a sensitivity of 91.7%, hsa-miR-485-5p showed 96.4% specificity, 90% sensitivity, and for HSP90 89.3%, 70% specificity and sensitivity, respectively. Those specificities and sensitivities were superior to the classical CRC TMs. A significant negative correlation was found between hsa-miR-485-5p with lncRNA NNT-AS1 (r = -0.933) expression fold change or with HSP90 protein blood level (r = -0.997), but, significant positive correlation was there between lncRNA NNT-AS1 and HSP90 (r = 0.927). LncRNA NNT-AS1/hsa-miR-485-5p/HSP90 axis could be a prospect for CRC development as well as diagnosis. Being correlated and related to CRC histologic grades 1-3, therefore, lncRNA NNT-AS1/hsa-miR-485-5p/HSP90 axis (not individually) expression approved clinically and in silico, could aid treatment precision.

Role of Ganetespib, an HSP90 Inhibitor, in Cancer Therapy: From Molecular Mechanisms to Clinical Practice

Heat-shock proteins are upregulated in cancer and protect several client proteins from degradation. Therefore, they contribute to tumorigenesis and cancer metastasis by reducing apoptosis and enhancing cell survival and proliferation. These client proteins include the estrogen receptor (ER), epidermal growth factor receptor (EGFR), insulin-like growth factor-1 receptor (IGF-1R), human epidermal growth factor receptor 2 (HER-2), and cytokine receptors. The diminution of the degradation of these client proteins activates different signaling pathways, such as the PI3K/Akt/NF-κB, Raf/MEK/ERK, and JAK/STAT3 pathways. These pathways contribute to hallmarks of cancer, such as self-sufficiency in growth signaling, an insensitivity to anti-growth signals, the evasion of apoptosis, persistent angiogenesis, tissue invasion and metastasis, and an unbounded capacity for replication. However, the inhibition of HSP90 activity by ganetespib is believed to be a promising strategy in the treatment of cancer because of its low adverse effects compared to other HSP90 inhibitors. Ganetespib is a potential cancer therapy that has shown promise in preclinical tests against various cancers, including lung cancer, prostate cancer, and leukemia. It has also shown strong activity toward breast cancer, non-small cell lung cancer, gastric cancer, and acute myeloid leukemia. Ganetespib has been found to cause apoptosis and growth arrest in these cancer cells, and it is being tested in phase II clinical trials as a first-line therapy for metastatic breast cancer. In this review, we will highlight the mechanism of action of ganetespib and its role in treating cancer based on recent studies.

Long noncoding RNA (lncRNA) HOTAIR: Pathogenic roles and therapeutic opportunities in gastric cancer

Gastric cancer is one of the first malignant cancers in the world and a large number of people die every year due to this disease. Many genetic and epigenetic risk factors have been identified that play a major role in gastric cancer. HOTAIR is an effective epigenetic agent known as long noncoding RNA (lncRNA). HOTAIR has been described to have biological functions in biochemical and cellular processes through interactions with many factors, leading to genomic stability, proliferation, survival, invasion, migration, metastasis, and drug resistance. In the present article, we reviewed the prognostic value of the molecular mechanisms underlying the HOTAIR regulation and its function in the development of Gastric Cancer, whereas elucidation of HOTAIR–protein and HOTAIR–DNA interactions can be helpful in the identification of cancer processes, leading to the development of potential therapeutic strategies.

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.

Coptidis Rhizoma Suppresses Metastatic Behavior by Inhibiting TGF-β-Mediated Epithelial-Mesenchymal Transition in 5-FU-Resistant HCT116 Cells

Colorectal cancer (CRC) is the second most lethal malignancy worldwide. The high mortality rate of CRC is largely due to cancer metastasis. Recently, suppressing epithelial-to-mesenchymal transition (EMT) has been considered a promising strategy for treating metastatic cancer, especially drug-resistant metastatic cancer. The present study aimed to evaluate the antimetastatic effect of Coptidis Rhizoma, as well as the potential underlying mechanisms, using a 5-fluorouracil-resistant colon tumor cell model (HCT116/R). Coptidis Rhizoma 30% ethanol extract (CRE) significantly inhibited HCT116/R cells migration and invasion. CRE effectively inhibited EMT in HCT116/R cells by upregulating the expression of an epithelial marker (E-cadherin) and downregulating the expression of mesenchymal markers (vimentin, Snail, and ZEB2) at both the protein and gene levels. Immunofluorescence assays also confirmed consistent patterns in the levels of E-cadherin and vimentin. In addition, the anti-EMT activity of CRE and its related effects were associated with the CRE-mediated suppression of the TGF-β pathway, as shown by changes in the levels of downstream molecules (phosphorylated Akt and p38), and inhibition of migration, invasion, and protein expression of TGF-β after treatment/cotreatment with a TGF-β inhibitor (SB431542). In conclusion, Coptidis Rhizoma exerts an antimetastatic effect, especially in the treatment of drug-resistant cancer, and the possible mechanisms are associated with inhibiting EMT via TGF-β signaling. Thus, Coptidis Rhizoma will likely become a potential therapeutic candidate for simultaneously mitigating drug resistance and metastasis in CRC.

The Effect of Dynamic, In Vivo-like Oxaliplatin on HCT116 Spheroids in a Cancer-on-Chip Model Is Representative of the Response in Xenografts

The cancer xenograft model in which human cancer cells are implanted in a mouse is one of the most used preclinical models to test the efficacy of novel cancer drugs. However, the model is imperfect; animal models are ethically burdened, and the imperfect efficacy predictions contribute to high clinical attrition of novel drugs. If microfluidic cancer-on-chip models could recapitulate key elements of the xenograft model, then these models could substitute the xenograft model and subsequently surpass the xenograft model by reducing variation, increasing sensitivity and scale, and adding human factors. Here, we exposed HCT116 colorectal cancer spheroids to dynamic, in vivo-like, concentrations of oxaliplatin, including a 5 day drug-free period, on-chip. Growth inhibition on-chip was comparable to existing xenograft studies. Furthermore, immunohistochemistry showed a similar response in proliferation and apoptosis markers. While small volume changes in xenografts are hard to detect, in the chip-system, we could observe a temporary growth delay. Lastly, histopathology and a pharmacodynamic model showed that the cancer spheroid-on-chip was representative of the proliferating outer part of a HCT116 xenograft, thereby capturing the major driver of the drug response of the xenograft. Hence, the cancer-on-chip model recapitulated the response of HCT116 xenografts to oxaliplatin and provided additional drug efficacy information.

Epigenetic Approaches to Overcome Fluoropyrimidines Resistance in Solid Tumors

Simple Summary

Fluoropyrimidines represent the backbone of many combination chemotherapy regimens for the treatment of solid cancers but are still associated with toxicity and mechanisms of resistance. In this review, we focused on the epigenetic modifiers histone deacetylase inhibitors (HDACis) and on their ability to regulate specific genes and proteins involved in the fluoropyrimidine metabolism and resistance mechanisms. We presented emerging preclinical and clinical studies, highlighting the mechanisms by which HDACis can prevent/overcome the resistance and/or enhance the therapeutic efficacy of fluoropyrimidines, potentially reducing their toxicity, and ultimately improving the overall survival of cancer patients.

Abstract

Although fluoropyrimidines were introduced as anticancer agents over 60 years ago, they are still the backbone of many combination chemotherapy regimens for the treatment of solid cancers. Like other chemotherapeutic agents, the therapeutic efficacy of fluoropyrimidines can be affected by drug resistance and severe toxicities; thus, novel therapeutic approaches are required to potentiate their efficacy and overcome drug resistance. In the last 20 years, the deregulation of epigenetic mechanisms has been shown to contribute to cancer hallmarks. Histone modifications play an important role in directing the transcriptional machinery and therefore represent interesting druggable targets. In this review, we focused on histone deacetylase inhibitors (HDACis) that can increase antitumor efficacy and overcome resistance to fluoropyrimidines by targeting specific genes or proteins. Our preclinical data showed a strong synergistic interaction between HDACi and fluoropyrimidines in different cancer models, but the clinical studies did not seem to confirm these observations. Most likely, the introduction of increasingly complex preclinical models, both in vitro and in vivo, cannot recapitulate human complexity; however, our analysis of clinical studies revealed that most of them were designed without a mechanistic approach and, importantly, without careful patient selection.

Ins and Outs of Heat Shock Proteins in Colorectal Carcinoma: Its Role in Carcinogenesis and Therapeutic Perspectives

Cancer cells can reprogram their metabolic activities and undergo uncontrolled proliferation by utilizing the power of heat shock proteins (HSPs). HSPs are highly conserved chaperones that facilitate the folding of intracellular proteins under stress. Constitutively, HSPs are expressed at low levels, but their expression upregulates in response to a wide variety of insults, including anticancer drugs, allowing cancer cells to develop chemoresistance. In recent years, several researchers have reported that HSPs could be an important therapeutic target in difficult-to-treat cancers such as colorectal carcinoma (CRC). Worldwide, CRC is the second most common type of cancer and the second leading cause of cancer-related deaths. The molecular complexity of CRC and the coexisting inflammatory conditions present a significant obstacle to developing effective treatment. Recently, considerable progress has been made in enhancing our understanding of the role of HSPs in CRC pathogenesis. Moreover, novel therapeutic strategies targeting HSPs, either alone or in combination with other anticancer agents, have been reported. Herein, we present an overview of the functional mechanisms and the diagnostic and prognostic potential of HSPs in CRC. We also discuss emerging anti-CRC strategies based on targeting HSPs.

Recent advances in heat shock proteins in cancer diagnosis, prognosis, metabolism and treatment

Heat shock proteins (HSPs) are a group of proteins, also known as molecular chaperones, which participate in protein folding and maturation in response to stresses or high temperature. According to their molecular weights, mammalian HSPs are classified into HSP27, HSP40, HSP60, HSP70, HSP90, and large HSPs. Previous studies have revealed that HSPs play important roles in oncogenesis and malignant progression because they can modulate all six hallmark traits of cancer. Because of this, HSPs have been propelled into the spotlight as biomarkers for cancer diagnosis and prognosis, as well as an exciting anticancer drug target. However, the relationship between the expression level of HSPs and their activity and cancer diagnosis, prognosis, metabolism and treatment is not clear and has not been completely established. Herein, this review summarizes and discusses recent advances and perspectives in major HSPs as biomarkers for cancer diagnosis, as regulators for cancer metabolism or as therapeutic targets for cancer therapy, which may provide new directions to improve the accuracy of cancer diagnosis and develop more effective and safer anticancer therapeutics.

An Update on the Potential Roles of E2F Family Members in Colorectal Cancer

Colorectal cancer (CRC) is a major health burden worldwide, and thus, optimised diagnosis and treatments are imperative. E2F transcription factors (E2Fs) are a family of transcription factors consisting of eight genes, contributing to the oncogenesis and development of CRC. Importantly, E2Fs control not only the cell cycle but also apoptosis, senescence, DNA damage response, and drug resistance by interacting with multiple signaling pathways. However, the specific functions and intricate machinery of these eight E2Fs in human CRC remain unclear in many respects. Evidence on E2Fs and CRC has been scattered on the related regulatory genes, microRNAs (miRNAs), and competing endogenous RNAs (ceRNAs). Accordingly, some drugs targeting E2Fs have been transferred from preclinical to clinical application. Herein, we have systemically reviewed the current literature on the roles of various E2Fs in CRC with the purpose of providing possible clinical implications for patient diagnosis and prognosis and future treatment strategy design, thereby furthering the understanding of the E2Fs.

Capsaicin Acts Through Reducing P38 MAPK-Dependent Thymidylate Synthase Expression to Enhance 5-Fluorouracil-Induced Cytotoxicity in Human Lung Cancer Cells

Capsaicin, an ingredient of green and red bell peppers, shows anticancer activity in several malignant cell lines. Thymidylate synthase (TS) is a well-validated anticancer drug target in non-small cell lung cancer (NSCLC) cells. However, whether capsaicin and 5-fluorouracil (5-FU) induce synergistic cytotoxicity in NSCLC cells by regulating TS expression is unclear. This study investigated the cytotoxicity of capsaicin and 5-FU co-treatment on two hoursuman lung adenocarcinoma cell lines, H520 and H1703, and the underlying mechanisms. Capsaicin decreased TS expression in a p38 mitogen-activated protein kinase (MAPK) inactivation–dependent manner in H520 and H1703 cells. Enhancement of p38 MAPK activity by transfection with constitutive active mitogen-activated protein kinase kinase six vectors increased TS expression and cell survival. In addition, capsaicin and 5-FU co-treatment enhanced synergistic cytotoxicity and inhibited cell growth associated with TS downregulation and p38 MAPK inactivation in H520 and H1703 cells. Capsaicin and 5-FU co-treatment did not affect the cellular content of capsaicin. These results show that capsaicin may be combined with 5-FU to treat NSCLC.

5-Fluorouracil (5-FU) resistance and the new strategy to enhance the sensitivity against cancer: Implication of DNA repair inhibition

5-Fluorouracil (5-FU) has been an important anti-cancer drug to date. With an increase in the knowledge of its mechanism of action, various treatment modalities have been developed over the past few decades to increase its anti-cancer activity. But drug resistance has greatly affected the clinical use of 5-FU. Overcoming this chemoresistance is a challenge due to the presence of cancer stem cells like cells, cancer recurrence, metastasis, and angiogenesis. In this review, we have systematically discussed the mechanism of 5-FU resistance and advent strategies to increase the sensitivity of 5-FU therapy including resistance reversal. Special emphasis has been given to the cancer stem cells (CSCs) mediated 5-FU chemoresistance and its reversal process by different approaches including the DNA repair inhibition process.

Controlled pharmacokinetic anti-cancer drug concentration profiles lead to growth inhibition of colorectal cancer cells in a microfluidic device

We present a microfluidic device to expose cancer cells to a dynamic, in vivo-like concentration profile of a drug, and quantify efficacy on-chip. About 30% of cancer patients receive drug therapy. In conventional cell culture experiments drug efficacy is tested under static concentrations, e.g. 1 μM for 48 hours, whereas in vivo, drug concentration follows a pharmacokinetic profile with an initial peak and a decline over time. With the rise of microfluidic cell culture models, including organs-on-chips, there are opportunities to more realistically mimic in vivo-like concentrations. Our microfluidic device contains a cell culture chamber and a drug-dosing channel separated by a transparent membrane, to allow for shear stress-free drug exposure and label-free growth quantification. Dynamic drug concentration profiles in the cell culture chamber were controlled by continuously flowing controlled concentrations of drug in the dosing channel. The control over drug concentrations in the cell culture chambers was validated with fluorescence experiments and numerical simulations. Exposure of HCT116 colorectal cancer cells to static concentrations of the clinically used drug oxaliplatin resulted in a sensible dose-effect curve. Dynamic, in vivo-like drug exposure also led to statistically significant lower growth compared to untreated control. Continuous exposure to the average concentration of the in vivo-like exposure seems more effective than exposure to the peak concentration (Cmax) only. We expect that our microfluidic system will improve efficacy prediction of in vitro models, including organs-on-chips, and may lead to future clinical optimization of drug administration schedules.

Thrombomodulin alfa prevents oxaliplatin-induced neuropathic symptoms through activation of thrombin-activatable fibrinolysis inhibitor and protein C without affecting anti-tumor activity

Oxaliplatin, a platinum-based chemotherapeutic agent, is widely used to treat colorectal cancer, but it induces peripheral neuropathy as a serious dose-limiting side effect. Recently, thrombomodulin alfa, a recombinant human soluble thrombomodulin, was reported to prevent oxaliplatin-induced peripheral neuropathy in a clinical phase 2 study. Here we conducted preclinical pharmacology studies. Rats were given oxaliplatin (6 mg/kg) intravenously to induce mechanical hyperalgesia associated with peripheral neuropathy. Single intravenous administration of thrombomodulin alfa (0.1, 0.3, 1 mg/kg) dose dependently prevented the development of oxaliplatin-induced mechanical hyperalgesia, with no sex difference in the efficacy. The preventative effect of thrombomodulin alfa on mechanical hyperalgesia was attenuated by antithrombin or carboxypeptidase inhibitor. In addition, carboxypeptidase B, a homolog of activated thrombin-activatable fibrinolysis inhibitor (TAFI) and human-derived activated protein C, prevented mechanical hyperalgesia, whereas antithrombin or other anti-coagulants did not. These results suggest that thrombomodulin alfa prevents sensory symptoms of oxaliplatin-induced peripheral neuropathy through the activation of TAFI and protein C by modulating thrombin activity, but the effects are independent of an anticoagulant effect. On the other hand, thrombomodulin alfa did not affect the anti-cancer activity of oxaliplatin on human colon cancer cell lines or mice transplanted with HCT116 cells. These results indicate that thrombomodulin alfa prevents sensory symptoms of oxaliplatin-induced peripheral neuropathy without affecting the anti-tumor activity of oxaliplatin. Therefore, thrombomodulin alfa is a promising drug to prevent the symptoms of oxaliplatin-induced peripheral neuropathy.

A comprehensive review of the roles of E2F1 in colon cancer

E2F transcription factor 1 (E2F1) is a member of the E2F family of transcription factors. E2F1 binds to DNA with dimerization partner (DP) proteins through an E2 recognition site. The dissociation of E2F1 from retinoblastoma (Rb) protein recovers its transcriptional activity, which drives the cell cycle from the G1 to S phase. E2F1 has been shown to be involved in cellular proliferation, differentiation, and apoptosis in colon cancer. It was recently found that E2F1 also participates in the metastasis and chemoresistance of colon cancer. There are abundant experimental data regarding the actions of E2F1, which can be grouped as either pro-tumorigenic or pro-apoptotic. Despite a growing interest and plentiful data, there is currently no review that focuses on the role of E2F1 in colon cancer. Research on E2F1 and colon cancer has been scattered over various genes and microRNAs (miRNAs) that affect E2F1 expression. Here, we provide the first review that aims to consider and dissect all of the elucidated complex behaviors of E2F1 in colon cancer. This review also provides an analysis and conclusion regarding the current understanding of E2F1 in colon cancer in order to facilitate the direction of future research.

Combination of Anti-Cancer Drugs with Molecular Chaperone Inhibitors

Most molecular chaperones belonging to heat shock protein (HSP) families are known to protect cancer cells from pathologic, environmental and pharmacological stress factors and thereby can hamper anti-cancer therapies. In this review, we present data on inhibitors of the heat shock response (particularly mediated by the chaperones HSP90, HSP70, and HSP27) either as a single treatment or in combination with currently available anti-cancer therapeutic approaches. An overview of the current literature reveals that the co-administration of chaperone inhibitors and targeting drugs results in proteotoxic stress and violates the tumor cell physiology. An optimal drug combination should simultaneously target cytoprotective mechanisms and trigger the imbalance of the tumor cell physiology.

National Cancer Institute (NCI) state of the science: Targeted radiosensitizers in colorectal cancer

Colorectal cancer (CRC) represents a major public health problem as the second leading cause of cancer-related mortality in the United States. Of an estimated 140,000 newly diagnosed CRC cases in 2018, roughly one-third of these patients will have a primary tumor located in the distal large bowel or rectum. The current standard-of-care approach includes curative-intent surgery, often after preoperative (neoadjuvant) radiotherapy (RT), to increase rates of tumor down-staging, clinical and pathologic response, as well as improving surgical resection quality. However, despite advancements in surgical techniques, as well as sharpened precision of dosimetry offered by contemporary RT delivery platforms, the oncology community continues to face challenges related to disease relapse. Ongoing investigations are aimed at testing novel radiosensitizing agents and treatments that might exploit the systemic antitumor effects of RT using immunotherapies. If successful, these treatments may usher in a new curative paradigm for rectal cancers, such that surgical interventions may be avoided. Importantly, this disease offers an opportunity to correlate matched paired biopsies, radiographic response, and molecular mechanisms of treatment sensitivity and resistance with clinical outcomes. Herein, the authors highlight the available evidence from preclinical models and early-phase studies, with an emphasis on promising developmental therapeutics undergoing prospective validation in larger scale clinical trials. This review by the National Cancer Institute's Radiation Research Program Colorectal Cancer Working Group provides an updated, comprehensive examination of the continuously evolving state of the science regarding radiosensitizer drug development in the curative treatment of CRC.

Synergistic effect of kaempferol and 5‑fluorouracil on the growth of colorectal cancer cells by regulating the PI3K/Akt signaling pathway

Combination chemotherapy with chemosensitizers can exert synergistic therapeutic effects, reduce toxicity, and delay the induction of drug resistance. In the present study, the antitumor effects were investigated, and the possible underlying mechanisms of kaempferol combined with 5‑fluorouracil (5‑FU) in colorectal cancer cells were explored. HCT‑8 or HCT‑116 cells were treated with various concentrations of kaempferol and/or 5‑FU for the indicated time‑points. An MTT assay was used to determine cell viability, whereas the synergistic effects were assessed by calculating the combination indices of kaempferol and 5‑FU. Annexin V analysis and Hoechst staining were used to determine cell apoptosis. q‑PCR and western blotting were performed to determine the expression levels of Bax, Bcl‑2, thymidylate synthase (TS), PTEN, PI3K, AKT, and p‑AKT. The combination of kaempferol and 5‑FU was determined to be more effective in inhibiting cell viability than either of the agents alone. The inhibition of tumors in response to kaempferol and 5‑FU was associated with the reduction in proliferation ability and stimulation of apoptosis. The protein results indicated that kaempferol and 5‑FU could significantly upregulate the expression levels of Bax and downregulate the expression levels of Bcl‑2 and TS. Furthermore, the combination treatment greatly inhibited the activation of the PI3K/Akt pathway, suggesting the involvement of this pathway in the synergistic effects. The present study demonstrated that kaempferol has a synergistic effect with 5‑FU by inhibiting cell proliferation and inducing apoptosis in colorectal cancer cells via suppression of TS or attenuation of p‑Akt activation. The combination of kaempferol and 5‑FU may be used as an effective therapeutic strategy for colorectal cancer.

Luminespib plus pemetrexed in patients with non-squamous non-small cell lung cancer

BACKGROUND

Luminespib (AUY922) is a second-generation heat shock protein 90 (HSP90) inhibitor with demonstrated activity in non-small cell lung cancer (NSCLC). Since luminespib reduces levels of dihydrofolate reductase (DHFR), a key enzymatic target of pemetrexed, we assessed the safety and tolerability of luminespib in combination with pemetrexed in patients with previously treated metastatic non-squamous non-small cell lung cancer (NSCLC). We also sought to study the pharmacokinetics and correlate tumor dihydrofolate reductase (DHFR) expression with clinical response.

METHODS

Patients received weekly luminespib at either 40 mg/m², 55 mg/m², or 70 mg/m² according to a standard 3 + 3 dose-escalation design along with pemetrexed at 500 mg/m² followed by an expansion at the maximum tolerated dose (MTD).

RESULTS

Two-dose limiting toxicities (DLTs) were experienced in the 70 mg/m2 cohort, therefore the MTD was determined to be 55 mg/m². 69% (N = 9) of patients experienced ophthalmologic toxicity related to luminespib. Maximum serum concentration (Cmax) of luminespib was associated with increased grade 2 drug related adverse events (DRAEs) (r_s = 0.74, P <  0.01), with volume of distribution (V_D) inversely associated with the number of DRAEs (r_s = - 0.81, P =  0.004) and ophthalmologic related DRAEs (r_s = - 0.65, P =  0.04). The best response was partial response in one patient for 20 months, prior to expiration of all luminespib. Amongst patients treated at the MTD, the objective response rate was 14%.

CONCLUSION

In patients with previously treated metastatic NSCLC, the MTD of luminespib in combination with pemetrexed was 55 mg/m² per week. The combination of luminespib and pemetrexed demonstrated clinical activity. Tolerability of luminespib with pemetrexed is limited by ocular toxicity.

Xanthium strumarium´s xanthatins induces mitotic arrest and apoptosis in CT26WT colon carcinoma cells

BACKGROUND

Colorectal cancer is one of the most common malignancies worldwide and is associated with high mortality rates. We previously reported that Xanthium strumarium L. induces mitotic arrest in proliferating cells, a process mediated by xanthatins.

HYPOTHESIS/AIM

The aim of this work is to study if xanthatins, isolated from X. strumarium total extract, affect the proliferative capacity of CT26WT colon cancer cells and, in consequence, if tumor growth and proliferation of (lung) metastatic sites can also be arrested in vivo.

STUDY DESIGN

This study consisted of both in vitro and in vivo experiments involving the CT26WT cell line and a subcutaneous mouse model of colon cancer. In vitro cell cycle progression, in vivo tumoral growth and anti-metastatic activity were analyzed to investigate whether xanthatins of X. strumarium induce mitotic arrest in proliferating colorectal carcinoma.

RESULTS

Our in vitro results show that X. strumarium, mediated by xanthatins, induces G₂/M arrest and impair anaphase entrance. This leads to a significant induction of apoptotic and necrotic in CT26WT cells, demonstrating their significant anti-proliferative activity through interfering with the mitotic apparatus. Furthermore, our in vivoresults reveal that X. strumarium inhibits both tumor growth and metastasis progression.

CONCLUSION

X. strumarium antitumor activities are mainly mediated by xanthatins through inhibition of tumor growth and metastasis, inducing mitotic arrest and apoptosis in colon carcinoma cells. These findings further confirm the therapeutic potential of X. strumarium in colorectal cancer.

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

Resistance of pancreatic ductal adenocarcinoma (PDAC) to radiotherapy and chemotherapy represents a significant clinical issue. Although the mechanisms of resistance are multi-faceted, client proteins of heat shock protein 90 (HSP90) such as hypoxia induced factor-1α (HIF-1α) have a central role in this process. The purpose of this investigation was to evaluate inhibition of HSP90 as a therapeutic strategy for radiosensitization in pancreatic cancer. Ganetespib, a selective inhibitor of HSP90, was evaluated as a radio-sensitizer in setting of PDAC. Inhibition of HSP90 by ganetespib potentiated the ability of radiation therapy to limit cell proliferation and colony formation in vitro. HIF-1α expression was upregulated by irradiation and HIF-1α-overexpressing stable cell lines were resistant to radiation. Inhibition of HSP90 with ganetespib reversed the effects of HIF-1α overexpression, by reducing signaling via proliferative, angiogenic and anti-apoptotic pathways. The potentiation of the antitumor effects of chemoradiotherapy by ganetespib and modulation of key pathways (e.g. HIF-1α, STAT3, and AKT) was confirmed in vivo in nude mice bearing HPAC xenograft tumors. These novel data highlight HIF-1α-mediated mechanisms of HSP90 inhibition that sensitize PDAC cells to chemoradiotherapy. This pathway and its pleiotropic effects warrant further evaluation in concert with conventional therapy in pancreatic cancer clinical trials.

Combination therapies with HSP90 inhibitors against colorectal cancer

Oncogene stability and homeostasis mediated by the HSP90 chaperone is a crucial protection trait of cancer cells. Therefore, HSP90 represents an attractive therapeutic target for many cancers, including colorectal cancer. Although monotherapy has limited clinical efficacy, preclinical and early-phase clinical studies indicate improved antitumor activity when HSP90 inhibitors are combined with chemotherapies or targeted agents. This may be further improved with a biomarker-guided approach based on oncogenic HSP90 clients, or stratification based on the consensus molecular subtypes of colorectal cancer, suggesting a synergistic activity with 5-fluorouracil in preclinical models of the chemorefractory mesenchymal subtype. Furthermore, HSP90 inhibition may activate mechanisms to turn non-immunogenic tumors hot and improve their recognition by the immune system, suggesting synergy with immune checkpoint blockade.

Prognostic significance of periostin in colorectal cancer

Accumulating evidence suggests that periostin is frequently upregulated in tissue injury, inflammation, fibrosis and tumor progression. Periostin expression in cancer cells can promote metastatic potential of colorectal cancer (CRC) via activating PI3K/Akt signaling pathway. Moreover, periostin is observed mainly in tumor stroma and cytoplasm of cancer cells, which may facilitate aggressiveness of CRC. In this review, we summarize information regarding periostin to emphasize its role as a prognostic marker of CRC.

Manuka honey synergistically enhances the chemopreventive effect of 5-fluorouracil on human colon cancer cells by inducing oxidative stress and apoptosis, altering metabolic phenotypes and suppressing metastasis ability

The development of chemo-sensitizers is urgently needed to overcome 5-fluorouracil (5-FU) therapeutic resistance and adverse toxicity in colorectal cancer. This work aims to evaluate the synergic effects of 5-FU and Manuka honey (MH), a rich source of bioactive compounds, in enhancing the anticancer effects of this drug on human colon cancer HCT-116 and LoVo cells. Compared to 5-FU alone, MH synergistically enhanced the chemotherapeutic effects of 5-FU, by reducing cell proliferation through the suppression of EGFR, HER2, p-Akt and p-mTOR expression, and promoting apoptosis by the modulation pro-apoptotic (p53, Bax, Cyto c, FasL caspase-3, -8, -9 and cleave-PARP) and anti-apoptotic (Bcl-2) markers. The activations of p-p38MAPK and p-Erk1/2 pathways and ROS production were also involved in this process. Downregulation of transcription factor (NF-κB and Nrf2) and antioxidant enzyme activity (SOD, catalase, glutathione peroxidase and glutathione reductase) and expression (SOD, catalase and HO-1) were more evident after the combined treatment, leading to more cell death by oxidative stress. Moreover, additive effects were also observed by increasing lipid and protein oxidation and arresting cell cycle. All the parameters of mitochondrial respiration and glycolysis function decreased and both cells entered the quiescent stage after the combined treatments. MH also influenced the anti-metastasis effects of 5-FU by decreasing migration ability, suppressing the expression of MMP-2, MMP-9 and increasing N-cadherin and E-cadherin. In conclusion, MH could be a useful preventive or adjuvant agent in the treatment of colorectal cancer with 5-FU.

A novel HSP90 inhibitor with reduced hepatotoxicity synergizes with radiotherapy to induce apoptosis, abrogate clonogenic survival, and improve tumor control in models of colorectal cancer

The chaperone heat shock protein 90 (HSP90) crucially supports the maturation, folding, and stability of a variety of client proteins which are of pivotal importance for the survival and proliferation of cancer cells. Consequently, targeting of HSP90 has emerged as an attractive strategy of anti-cancer therapy, and it appears to be particularly effective in the context of molecular sensitization towards radiotherapy as has been proven in preclinical models of different cancer entities. However, so far the clinical translation has largely been hampered by suboptimal pharmacological properties and serious hepatotoxicity of first- and second-generation HSP90 inhibitors. Here, we report on NW457, a novel radicicol-derived member of the pochoxime family with reduced hepatotoxicity, how it inhibits the DNA damage response and how it synergizes with ionizing irradiation to induce apoptosis, abrogate clonogenic survival, and improve tumor control in models of colorectal cancer in vitro and in vivo.

Colorectal Cancer Consensus Molecular Subtypes Translated to Preclinical Models Uncover Potentially Targetable Cancer Cell Dependencies

Purpose: Response to standard oncologic treatment is limited in colorectal cancer. The gene expression-based consensus molecular subtypes (CMS) provide a new paradigm for stratified treatment and drug repurposing; however, drug discovery is currently limited by the lack of translation of CMS to preclinical models.Experimental Design: We analyzed CMS in primary colorectal cancers, cell lines, and patient-derived xenografts (PDX). For classification of preclinical models, we developed an optimized classifier enriched for cancer cell-intrinsic gene expression signals, and performed high-throughput in vitro drug screening (n = 459 drugs) to analyze subtype-specific drug sensitivities.Results: The distinct molecular and clinicopathologic characteristics of each CMS group were validated in a single-hospital series of 409 primary colorectal cancers. The new, cancer cell-adapted classifier was found to perform well in primary tumors, and applied to a panel of 148 cell lines and 32 PDXs, these colorectal cancer models were shown to recapitulate the biology of the CMS groups. Drug screening of 33 cell lines demonstrated subtype-dependent response profiles, confirming strong response to EGFR and HER2 inhibitors in the CMS2 epithelial/canonical group, and revealing strong sensitivity to HSP90 inhibitors in cells with the CMS1 microsatellite instability/immune and CMS4 mesenchymal phenotypes. This association was validated in vitro in additional CMS-predicted cell lines. Combination treatment with 5-fluorouracil and luminespib showed potential to alleviate chemoresistance in a CMS4 PDX model, an effect not seen in a chemosensitive CMS2 PDX model.Conclusions: We provide translation of CMS classification to preclinical models and uncover a potential for targeted treatment repurposing in the chemoresistant CMS4 group. Clin Cancer Res; 24(4); 794-806. ©2017 AACR.

Boosting the effects of hyperthermia-based anticancer treatments by HSP90 inhibition

Hyperthermia - application of supra-physiological temperatures to cells, tissues or organs - is a pleiotropic treatment that affects most aspects of cellular metabolism, but its effects on DNA are of special interest in the context of cancer research and treatment. Hyperthermia inhibits repair of various DNA lesions, including double-strand breaks (DSBs), making it a powerful radio- and chemosensitizer, with proven clinical efficacy in therapy of various types of cancer, including tumors of head and neck, bladder, breast and cervix. Among the challenges for hyperthermia-based therapies are the transient character of its effects, the technical difficulties in maintaining uniformly elevated tumor temperature and the acquisition of thermotolerance. Approaches to reduce or eliminate these challenges could simplify the application of hyperthermia, boost its efficacy and improve treatment outcomes. Here we show that a single, short treatment with a relatively low dose of HSP90 inhibitor Ganetespib potentiates cytotoxic as well as radio- and chemosensitizing effects of hyperthermia and reduces thermotolerance in cervix cancer cell lines. Ganetespib alone, applied at this low dose, has virtually no effect on survival of non-heated cells. Our results thus suggest that HSP90 inhibition can be a safe, simple and efficient approach to improving hyperthermia treatment efficacy and reducing thermotolerance, paving the way for in vivo studies.

Therapeutic potency of heat-shock protein-90 pharmacological inhibitors in the treatment of gastrointestinal cancer, current status and perspectives

Objectives

Heat-shock protein-90 (HSP90) chaperone machinery is critical to the folding, stability and activity of several client proteins including many responsible for tumour initiation, progression and metastasis. Overexpression of HSP90 is correlated with poor prognosis of GI cancer.

Key findings

Pharmacological inhibitors of HSP90 suppress tumorigenic effects of HSP90 by suppressing angiogenesis, survival, metastasis and drug resistance in GI cancer. This review summarizes the role of HSP90 inhibitors in the treatment of GI cancer.

Summary

We have presented different antitumour mechanisms of HSP90 inhibitors in cancer treatment. Suppression of HSP90 signalling via specific and novel pharmacological inhibitors is a potentially novel therapeutic approach for patients with GI cancer for a better understanding and hence a better management of this disease.

Epigenetic effects of inhibition of heat shock protein 90 (HSP90) in human pancreatic and colon cancer

Silencing of tumor suppressor and DNA repair genes through methylation plays a role in cancer development, growth and response to therapy in colorectal and pancreatic cancers. Heat shock protein 90 (HSP90) regulates transcription of DNA methyltransferase enzymes (DNMT). In addition, DNMTs are client proteins of HSP90. The aim of this study is to evaluate the effects of HSP90 inhibition on DNA methylation in colorectal and pancreatic cancer cell lines. Our data shows that inhibition of HSP90 using ganetespib resulted in downregulation of mRNA and protein expression of DNMT1, DNMT3A, and DNMT3B in HT-29 and MIA PaCa-2 cell lines. This in turn was associated with a drop in the fraction of methylated cytosine residues and re-expression of silenced genes including MLH-1, P16 and SPARC. These effects were validated in HT-29 tumors implanted subcutaneously in mice following in vivo administration of ganetespib. This work demonstrates the effectiveness of ganetespib, an HSP90 inhibitor in modulating DNA methylation through downregulation of DNMT expression.

Inhibiting heat shock protein 90 and the ubiquitin-proteasome pathway impairs metabolic homeostasis and leads to cell death in human pancreatic cancer cells

BACKGROUND

Heat shock protein 90 (HSP90) and the ubiquitin-proteasome pathway play crucial roles in the homeostasis of pancreatic cancer cells. This study combined for the first time the HSP90 inhibitor ganetespib (Gan) and the proteasome inhibitor carfilzomib (Carf) to target key mechanisms of homeostasis in pancreatic cancer. It was hypothesized that Gan plus Carf would elicit potent antitumor activity by modulating complementary homeostatic processes.

METHODS

In vitro and in vivo effects of this combination on mechanisms of cell growth and viability were evaluated with human pancreatic cancer cell lines (MIA PaCa-2 and HPAC).

RESULTS

Combined treatment with Gan and Carf significantly decreased cell viability. The mechanism varied by cell line and involved G₂ -M cell-cycle arrest accompanied by a consistent reduction in key cell-cycle regulatory proteins and concomitant upregulation of p27. Further studies revealed increased autophagy markers, including the upregulation of autophagy related 7 and light chain 3 cleavage, and evidence of apoptosis (increased Bax expression and processing of caspase 3). Immunoblot analyses confirmed the modulation of other pathways that influence cell viability, including phosphoinositide 3-kinase/Akt and nuclear factor κB. Finally, the treatment of athymic mice bearing HPAC tumors with Gan and Carf significantly reduced tumor growth in vivo. An immunoblot analysis of freshly isolated tumors from animals at the end of the study confirmed in vivo modulation of key signaling pathways.

CONCLUSIONS

The results reveal Gan plus Carf to be a promising combination with synergistic antiproliferative, apoptotic, and pro-autophagy effects in preclinical studies of pancreatic cancer and will further the exploration of the utility of this treatment combination in clinical trials. Cancer 2017;123:4924-33. © 2017 American Cancer Society.

lncRNA HOTAIR Contributes to 5FU Resistance through Suppressing miR-218 and Activating NF-κB/TS Signaling in Colorectal Cancer

One major reason for the failure of advanced colorectal cancer (CRC) treatment is the occurrence of chemoresistance to fluoropyrimidine (FU)-based chemotherapy. Long non-coding RNA HOTAIR has been considered as a pro-oncogene in multiple cancers. However, the precise functional mechanism of HOTAIR in chemoresistance is not well known. In this study, we investigated the biological and clinical role of HOTAIR in 5FU resistance in CRC. Our results showed that HOTAIR negatively regulated miR-218 expression in CRC through an EZH2-targeting miR-218-2 promoter regulatory axis. HOTAIR knockdown dramatically inhibited cell viability and induced G1-phase arrest by promoting miR-218 expression. VOPP1 was shown to be a functional target of miR-218, and the main downstream signaling, NF-κB, was inactivated by HOTAIR through the suppression of miR-218 expression. Additionally, HOTAIR knockdown partially reversed 5FU resistance through promoting miR-218 and inactivating NF-κB signaling. Furthermore, HOTAIR restrained 5FU-induced cytotoxicity on CRC cells through promotion of thymidylate synthase expression. More importantly, high HOTAIR expression was associated with poor response to 5FU treatment. In conclusion, we demonstrated that HOTAIR contributes to 5FU resistance through suppressing miR-218 and activating NF-κB signaling in CRC. Thus, HOTAIR may serve as a promising therapeutic target for CRC patients.

Cytotoxic effects of the newly-developed chemotherapeutic agents 17-AAG in combination with oxaliplatin and capecitabine in colorectal cancer cell lines

The use of heat shock protein 90 inhibitors like 17-allylamino-17-demethoxy-geldanamycin (17-AAG) has been recently introduced as an attractive anticancer therapy. It has been shown that 17-AAG may potentiate the inhibitory effects of some classical anticolorectal cancer (CRC) agents. In this study, two panels of colorectal carcinoma cell lines were used to evaluate the effects of 17-AAG in combination with capecitabine and oxaliplatin as double and triple combination therapies on the proliferation of CRC cell lines. HT-29 and all HCT-116 cell lines were seeded in culture media in the presence of different doses of the mentioned drugs in single, double, and triple combinations. Water-soluble tetrazolium-1 (WST-1) assay was used to investigate cell proliferation 24 h after treatments. Then, dose-response curves were plotted using WST-1outputs, and IC₅₀ values were determined. For double and triple combinations respectively 0.5 × IC₅₀ and 0.25 × IC₅₀ were used. Data was analyzed with the software CompuSyn. Drug interactions were analyzed using Chou-Talalay method to calculate the combination index (CI).The data revealed that 17-AAG shows a potent synergistic interaction (CI < 1) with oxaliplatin and capecitabine in double combinations (0.5 × IC₅₀) in both cell lines. In the case of triple combinations, the findings showed an antagonistic interaction (CI > 1) in HT-29 and a synergistic effect (CI < 1) in HCT-116 (0.25 × IC₅₀) cell lines. It was concluded that double combinations of 17-AAG with oxaliplatin or capecitabine might be effective against HCT-116 and HT-29 cell lines. However, in triple combinations, positive results were seen only against HCT-116. Further investigation is suggested to confirm the effectiveness of these combinations in clinical trials.

Periostin expression in intra-tumoral stromal cells is prognostic and predictive for colorectal carcinoma via creating a cancer-supportive niche

Periostin (POSTN) expression in cancer cells and circulation has been related to poor prognosis of colorectal carcinoma (CRC). However, the role of POSTN expressed in intra-tumoral stroma on CRC progression remains largely unknown. This study enrolled 1098 CRC patients who received surgical treatment in Shanghai and Guangzhou, Mainland China. In Shanghai cohort, immunohistochemistry score of stromal POSTN expression increased consecutively from adjacent mucosa, primary CRC tissues, to metastatic CRC tissues (P < 0.001), while medium- and high-stromal POSTN expression, rather than epithelial POSTN expression, independently predicted unfavorable prognoses of CRC, adjusted for covariates including TNM stage and postoperative chemotherapy in multivariate Cox models. The results in Shanghai cohort were faithfully replicated in Guangzhou cohort. Stromal POSTN expression dose-dependently predicted an unfavorable prognosis of stage III CRC patients with postoperative chemotherapy in both cohorts. POSTN derived from colonic fibroblasts or recombinant POSTN significantly promoted proliferation, anchorage independent growth, invasion, and chemo-resistance of CRC cells; whereas these effects were counteracted via targeting to PI3K/Akt or Wnt/β-catenin signaling pathway. CRC cell RKO-derived factor(s) significantly induced POSTN production in colonic fibroblasts and autocrine POSTN promoted proliferation, migration, and anchorage independent growth of fibroblasts. Conclusively, stromal POSTN is prognostic and predictive for CRC via creating a niche to facilitate cancer progression. Targeting POSTN-induced signaling pathways may be therapeutic options for metastatic or chemoresistant CRC.

Too much to handle - how gaining chromosomes destabilizes the genome

Most eukaryotic organisms are diploid, with 2 chromosome sets in their nuclei. Whole chromosomal aneuploidy, a deviation from multiples of the haploid chromosome number, arises from chromosome segregation errors and often has detrimental consequences for cells. In humans, numerical aneuploidy severely impairs embryonic development and the rare survivors develop disorders characterized by multiple pathologies. Moreover, as many as 75 % of malignant tumors display aneuploidy. Although the exact contribution of aneuploidy to tumorigenesis remains unclear, previous studies have suggested that aneuploidy may affect the maintenance of genome integrity. We found that human cells with extra chromosomes showed phenotypes suggestive of replication defects, a phenomenon which we went on to characterize as being due to the aneuploidy-driven downregulation of replication factors, in particular of the replicative helicase MCM2-7. Thus, missegregation of even a single chromosome can further promote genomic instability and thereby contribute to tumor development. In this review we will examine the possible causes of downregulation of replicative factors and discuss the consequences of genomic instability in aneuploid cells.

Astaxanthin enhances pemetrexed-induced cytotoxicity by downregulation of thymidylate synthase expression in human lung cancer cells

Pemetrexed, a multitargeted antifolate agent, has demonstrated clinical activity in non-small cell lung cancer (NSCLC) cells. Increased expression of thymidylate synthase (TS) is thought to be associated with resistance to pemetrexed. Astaxanthin exhibits a wide range of beneficial effects including anti-cancer and anti-inflammatory properties. In this study, we showed that down-regulating of TS expression in two NSCLC cell lines, human lung adenocarcinoma H1650 and squamous cell carcinoma H1703 cells, with astaxanthin were associated with decreased MKK1/2-ERK1/2 activity. Enforced expression of constitutively active MKK1 (MKK1-CA) vector significantly rescued the decreased TS mRNA and protein levels in astaxanthin-treated NSCLC cells. Combined treatment with a MKK1/2 inhibitor (U0126 or PD98059) further decreased the TS expression in astaxanthin-exposed NSCLC cells. Knockdown of TS using small interfering RNA (siRNA) or inhibiting ERK1/2 activity enhanced the cytotoxicity and cell growth inhibition of astaxanthin. Combination of pemetrexed and astaxanthin resulted in synergistic enhancing cytotoxicity and cell growth inhibition in NSCLC cells, accompanied with reduced activation of phospho-MKK1/2, phopho-ERK1/2, and TS expression. Overexpression of MKK1/2-CA reversed the astaxanthin and pemetrexed-induced synergistic cytotoxicity. Our findings suggested that the down-regulation of MKK1/2-ERK1/2-mediated TS expression by astaxanthin is an important regulator of enhancing the pemetrexed-induced cytotoxicity in NSCLC cells.

JD enhances the anti-tumour effects of low-dose paclitaxel on gastric cancer MKN45 cells both in vitro and in vivo

BACKGROUND

Gastric cancer is the third most common cause of cancer mortality worldwide, and paclitaxel (PTX) is one of the most widely used traditional drugs in gastric cancer therapy. However, the response to traditional therapy is limited by acquired chemo-resistance and side effects. Here, we establish a newly designed combination therapy consisting of a compound that is a structural variant of oridonin, i.e. Jesridonin (JD), and low-dose PTX for gastric cancer cells (MKN45) to investigate whether the anti-tumour activity of low-dose PTX could be enhanced when combined with JD.

METHODS

The interaction of JD and low-dose PTX was detected in MKN45 cells using the median-effect analysis method. The synergistic effect on cell viability and apoptosis was measured by MTT assay, colony formation assay, transient transfection, flow cytometry and Western blotting. The synergistic in vivo effect of JD plus low-dose PTX was evaluated in nude mouse xenograft models using H&E and TUNEL staining and Western blotting.

RESULTS

JD plus low-dose PTX showed a synergistic effect, as the combination indexes were less than 1. Additionally, a synergistic anti-proliferative and pro-apoptotic effect was detected for the combination of JD and low-dose PTX. The apoptotic mechanism induced by JD plus PTX revealed that the combination therapy synergistically activated the mitochondrial pathway.

CONCLUSION

Our findings suggest that JD enhances the anti-tumour effect of low-dose PTX on gastric carcinoma cancer cells in both vitro and in vivo, accompanied by activation of the mitochondrial pathway, which may present a more effective therapeutic strategy in gastric cancer treatment.

The novel HSP90 inhibitor AT13387 potentiates radiation effects in squamous cell carcinoma and adenocarcinoma cells

Overexpression of heat shock protein 90 (HSP90) is associated with increased tumor cell survival and radioresistance. In this study we explored the efficacy of the novel HSP90 inhibitor AT13387 and examined its radiosensitizing effects in combination with gamma-radiation in 2D and 3D structures as well as mice-xenografts. AT13387 induced effective cytotoxic activity and radiosensitized cancer cells in monolayer and tumor spheroid models, where low drug doses triggered significant synergistic effects on cell survival together with radiation. Furthermore, AT13387 treatment resulted in G2/M-phase arrest and significantly reduced the migration capacity. The expression of selected client proteins involved in DNA repair, cell-signaling and cell growth was downregulated in vitro, though the expression of most investigated proteins recurred after 8–24 h. These results were confirmed in vivo where AT13387 treated tumors displayed effective downregulation of HSP90 and its oncogenic client proteins.

In conclusion, our results demonstrate that AT13387 is a potent new cancer drug and effective radiosensitizer in vitro with an excellent in vivo efficacy. AT13387 treatment has the potential to improve external beam therapy and radionuclide therapy outcomes and restore treatment efficacy in cancers that are resistant to initial therapeutic regimes.

Acquired resistance to 5-fluorouracil via HSP90/Src-mediated increase in thymidylate synthase expression in colon cancer

5-fluorouracil (5-FU), one of the first-line chemotherapeutic agents for the treatment of gastrointestinal malignancies, has shown limited efficacy. The expression of thymidylate synthase (TYMS) has been reported to be associated with the resistance to 5-FU. Here, we demonstrate that the enhanced HSP90 function and subsequent activation of Src induce expression of TYMS and acquired resistance to 5-FU in colon cancer. We show that the persistent 5-FU treatment granted 5-FU-sensitive HCT116 colon cancer cells morphologic, molecular, and behavioral characteristic of the epithelial-mesenchymal transition (EMT), contributing to emergence of acquired resistance to 5-FU. HCT116/R, a HCT116 colon cancer cell subline carrying acquired resistance to 5-FU, showed increased expression and activation of HSP90's client proteins and transcriptional up-regulation of TYMS. Forced overexpression of HSP90 or constitutive active Src in HCT116 cells increased TYMS expression. Conversely, pharmacological blockade of HSP90 or Src in HCT116/R cells effectively suppressed the changes involved in 5-FU resistance in vitro and xenograft tumor growth, hematogenous spread, and metastatic tumor development in vivo. This study suggests a novel function of HSP90-Src pathway in regulation of TYMS expression and acquisition of 5-FU resistance. Thus, therapeutics targeting this pathway may be an effective clinical strategy to overcome 5-FU resistance in colon cancer.

Novel synthetic curcumin analogs as potent antiangiogenic agents in colorectal cancer

The transcription factor NF-κB plays a central role in angiogenesis in colorectal cancer (CRC). Curcumin is a natural dietary product that inhibits NF-κB. The objective of this study is to evaluate the antiangiogenic effects of curcumin and two potent synthetic analogues (EF31 and UBS109) in CRC. IC₅₀ values for curcumin, EF31, and UBS109 were determined in the HCT116 and HT-29 cell lines. HUVEC tube formation, egg CAM assay, and matrigel plug assays revealed decreased angiogenesis in cell lines treated with curcumin, EF31, or UBS109. Curcumin and its analogues significantly inhibited VEGF-A synthesis and secretion in both cell lines in association with loss of HIF-1α, COX-2, and p-STAT-3 expression. Nuclear NF-κB expression was inhibited by curcumin, EF31, and UBS109. Transfection of p65-NF-κB in HCT116 and HT-29 cells resulted in increased expression of HIF-1α, COX-2, STAT-3, and VEGF-A. Treatment with curcumin, EF31, or UBS109 inhibited these effects in transfected cell lines. In mice carrying HCT116 and HT-29 cell xenografts, EF31 and UBS109 inhibited subcutaneous tumor growth and potentiated the effects of oxaliplatin and 5-FU. Tumors from treated animals revealed inhibition of HIF-1α, COX-2, p-STAT-3, and VEGF expression. Our findings suggest that inhibition of NF-κB leading to decreased transcription and expression of HIF-1α, COX-2, STAT-3, and VEGF is a rational approach for antiangiogenic therapy in CRC. The distinctive properties of EF31 and UBS109 make them promising therapeutic agents for development in CRC as single agents or as part of combination chemotherapy regimens. © 2016 Wiley Periodicals, Inc.

Heat shock protein 90 is involved in the regulation of HMGA2-driven growth and epithelial-to-mesenchymal transition of colorectal cancer cells

High Mobility Group AT-hook 2 (HMGA2) is a nonhistone chromatin-binding protein which acts as a transcriptional regulating factor involved in gene transcription. In particular, overexpression of HMGA2 has been demonstrated to associate with neoplastic transformation and tumor progression in Colorectal Cancer (CRC). Thus, HMGA2 is a potential therapeutic target in cancer therapy. Heat Shock Protein 90 (Hsp90) is a chaperone protein required for the stability and function for a number of proteins that promote the growth, mobility, and survival of cancer cells. Moreover, it has shown strong positive connections were observed between Hsp90 inhibitors and CRC, which indicated their potential for use in CRC treatment by using combination of data mining and experimental designs. However, little is known about the effect of Hsp90 inhibition on HMGA2 protein expression in CRC. In this study, we tested the hypothesis that Hsp90 may regulate HMGA2 expression and investigated the relationship between Hsp90 and HMGA2 signaling. The use of the second-generation Hsp90 inhibitor, NVP-AUY922, considerably knocked down HMGA2 expression, and the effects of Hsp90 and HMGA2 knockdown were similar. In addition, Hsp90 knockdown abrogates colocalization of Hsp90 and HMGA2 in CRC cells. Moreover, the suppression of HMGA2 protein expression in response to NVP-AUY922 treatment resulted in ubiquitination and subsequent proteasome-dependant degradation of HMGA2. Furthermore, RNAi-mediated silencing of HMGA2 reduced the survival of CRC cells and increased the sensitivity of these cells to chemotherapy. Finally, we found that the NVP-AUY922-dependent mitigation of HMGA2 signaling occurred also through indirect reactivation of the tumor suppressor microRNA (miRNA), let-7a, or the inhibition of ERK-regulated HMGA2 involved in regulating the growth of CRC cells. Collectively, our studies identify the crucial role for the Hsp90-HMGA2 interaction in maintaining CRC cell survival and migration. These findings have significant implications for inhibition HMGA2-dependent tumorigenesis by clinically available Hsp90 inhibitors.

B7-H3 increases thymidylate synthase expression via the PI3k-Akt pathway

B7-H3, a member of the B7 family, has been reported to be highly expressed in colorectal cancer and is associated with poor prognosis and overall survival. In this study, we found that overexpression of B7-H3 protected SW80 and HCT8 cells from 5-fluorouracil (5-FU) using CCK-8 assays by inducing resistance to 5-FU chemotherapy. Further investigation has revealed elevated expression of thymidylate synthase (TS) and upregulation of the PI3-kinase (PI3K)/Akt pathway in B7-H3 overexpressing cells. The effects of B7-H3 on activation of the PI3K/Akt pathway and elevation of TS expression could be blocked by LY294002, a specific inhibitor of the PI3K signaling pathway. These results implied that B7-H3 can induce colorectal cancer cell resistance to 5-FU by increasing TS expression and PI3K/Akt/TS signaling and plays an important role during these processes. This study provides more proof concerning the non-immunology effect of B7 molecules, a reminder that both co-stimulatory or inhibitory effects and non-immunology effects should be devoted equal attention.

Targeting the Janus-activated kinase-2-STAT3 signalling pathway in pancreatic cancer using the HSP90 inhibitor ganetespib

BACKGROUND

Pancreatic cancer (PC) is an aggressive malignancy characterised by chemoresistance. HSP90 is important for stabilisation of proteins, cell signalling and malignant growth. We hypothesised that ganetespib, an HSP90 inhibitor, can inhibit PC cell growth by interfering with multiple signalling cascades, including the Janus-activated kinase (JAK)-STAT pathway, and act synergistically with chemotherapeutic drugs.

METHODS

The effects of ganetespib were evaluated in ASPC-1, HPAC, MIA PaCA-2 and PANC-1 cell lines using a cell proliferation assay. Effects on the expression of phosphoinositide 3-kinase (PI3K)/AKT, mitogen-activated protein kinase (MAPK) and JAK-STAT pathways were examined by Western blot. JAK2 and STAT3 were knocked down by transient transfection with JAK2 or STAT3 small interfering RNA. ASPC-1 and HPAC cell lines were tested for sensitivity to ganetespib, 5-fluorouracil/oxaliplatin, and gemcitabine/paclitaxel, alone and in combination, using an in vivo tumour xenograft model.

RESULTS

Ganetespib significantly decreased cell proliferation in all tested PC cell lines. Ganetespib decreased the activation of extracellular signal-related kinase (ERK), PI3K/AKT, and c-Jun NH2-terminal kinase (JNK) signalling molecules and diminished the activation of STAT3 in an additive manner with isolated downregulation of JAK2 expression. In animal models, ganetespib potentiated the effects of 5-fluouracil/oxaliplatin and gemcitabine/paclitaxel, as measured by tumour volume. Western blot analysis from tumours removed from animals confirmed the effects of ganetespib on PI3K/AKT, ERK and JNK pathways.

CONCLUSIONS

Ganetespib inhibits the growth of PC cells, an effect associated with downregulation of signalling through the JAK2-STAT3, PI3K/AKT and MAPK pathways. This provides preclinical proof-of-principle that ganetespib enhances the activity of chemotherapeutic agents and warrants further evaluation in PC clinical trials.

5-Fluoruracil blocked giant cell tumor progression by suppressing osteoclastogenesis through NF-kappaB signals and blocking angiogenesis

Giant cell tumor of bone (GCTB) is a bone destroying tumor comprised of spindle-like stromal cells and monocytes of myeloid lineage that are differentiated into osteoclast-like multinucleated giant cells. Nuclear factor-Kappa B (NF-κB) has been identified to be essential for GCT progression. Herein, we found that 5-Fluorouracil (5-FU), a widely used chemotherapeutics, is a promising anticancer agent for GCT both targeting spindle-like stromal cells and osteoclast giant cells through NF-κB pathway. In this study, in vitro 5-FU not only directly blocked both stromal cell- and RANKL-induced osteoclastogenesis through NF-κB pathway, but also indirectly inhibited osteoclast formation and angiogenesis by suppressing the expression of osteoclast-activating factors including IL-1β, MCP-1 and tumor angiogenesis factor VEGF in stromal cells. In vivo, we found that 5-FU blocked GCT progression through NF-κB pathway by utilizing our chick embryo chorioallantoic membrane (CAM) model. Taken together, our results suggest that 5-FU can inhibit GCT development by suppressing osteoclast formation through NF-κB pathway and blocking angiogenesis, and may serve as a novel agent in the treatment of GCT.