Intrinsic or acquired drug resistance and metastasis: are they linked phenotypes?

The role of histone H1.2 in pancreatic cancer metastasis and chemoresistance

AIMS

Pancreatic cancer (PC) is a highly metastatic malignant tumor of the digestive system. Drug resistance frequently occurs during cancer treatment process. This study aimed to explore the link between chemoresistance and tumor metastasis in PC and its possible molecular and cellular mechanisms.

METHODS

A Metastasis and Chemoresistance Signature (MCS) scoring system was built and validated based on metastasis- and chemoresistance-related genes using gene expression data of PC, and the model was applied to single-cell RNA sequencing data. The influence of linker histone H1.2 (H1-2) on PC was explored through in vitro and in vivo experiments including proliferation, invasion, migration, drug sensitivity, rescue experiments and immunohistochemistry, emphasizing its regulation with c-MYC signaling pathway.

RESULTS

A novel MCS scoring system accurately predicted PC patient survival and was linked to chemoresistance and epithelial-mesenchymal transition (EMT) in PC single-cell RNA sequencing data. H1-2 emerged as a significant prognostic factor, with its high expression indicating increased chemoresistance and EMT. This upregulation was mediated by c-MYC, which was also found to be highly expressed in PC tissues.

CONCLUSION

The MCS scoring system offers insights into PC chemoresistance and metastasis potential. Targeting H1-2 could enhance therapeutic strategies and improve PC patient outcomes.

Role of exosomes in the development, diagnosis, prognosis and treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer. It is characterized by occult onset resulting in most patients being diagnosed at advanced stages and with poor prognosis. Exosomes are nanoscale vesicles with a lipid bilayer envelope released by various cells under physiological and pathological conditions, which play an important role in the biological information transfer between cells. There is growing evidence that HCC cell-derived exosomes may contribute to the establishment of a favorable microenvironment that supports cancer cell proliferation, invasion, and metastasis. These exosomes not only provide a versatile platform for diagnosis but also serve as a vehicle for drug delivery. In this paper, we review the role of exosomes involved in the proliferation, migration, and metastasis of HCC and describe their application in HCC diagnosis and treatment. We also discuss the prospects of exosome application in HCC and the research challenges.

BIN1 in cancer: biomarker and therapeutic target

BACKGROUND

The bridging integrator 1 (BIN1) protein was originally identified as a pro-apoptotic tumor suppressor that binds to and inhibits oncogenic MYC transcription factors. BIN1 has complex physiological functions participating in endocytosis, membrane cycling, cytoskeletal regulation, DNA repair deficiency, cell-cycle arrest, and apoptosis. The expression of BIN1 is closely related to the development of various diseases such as cancer, Alzheimer's disease, myopathy, heart failure, and inflammation.

PURPOSE

Because BIN1 is commonly expressed in terminally differentiated normal tissues and is usually undetectable in refractory or metastatic cancer tissues, this differential expression has led us to focus on human cancers associated with BIN1. In this review, we discuss the potential pathological mechanisms of BIN1 during cancer development and its feasibility as a prognostic marker and therapeutic target for related diseases based on recent findings on its molecular, cellular, and physiological roles.

CONCLUSION

BIN1 is a tumor suppressor that regulates cancer development through a series of signals in tumor progression and microenvironment. It also makes BIN1 a feasible early diagnostic or prognostic marker for cancer.

Docosahexaenoic Acid, a Key Compound for Enhancing Sensitization to Drug in Doxorubicin-Resistant MCF-7 Cell Line

Drug resistance is a well-known and significant obstacle in the battle against cancer, rendering chemotherapy treatments often ineffective. To improve the effectiveness of chemotherapy, researchers are exploring the use of natural molecules that can enhance its ability to kill cancer cells and limit their spread. Docosahexaenoic acid (DHA), a lipid found in marine fish, has been shown to enhance the cytotoxicity of various anti-cancer drugs in vitro and in vivo. While the combined use of chemotherapeutic drugs with DHA demonstrated promising preliminary results in clinical trials, there is still a significant amount of information to be discovered regarding the precise mechanism of action of DHA. As the biological pathways involved in the chemosensitization of already chemoresistant MCF-7 cells are still not entirely unraveled, in this study, we aimed to investigate whether DHA co-treatment could enhance the ability of the chemotherapy drug doxorubicin to inhibit the growth and invasion of MCF-7 breast cancer cells (MCF-7/Dox) that had become resistant to the drug. Upon treating MCF-7/Dox cells with DHA or DHA-doxorubicin, it was observed that the DHA-doxorubicin combination effectively enhanced cancer cell death by impeding in vitro propagation and invasive ability. In addition, it led to an increase in doxorubicin accumulation and triggered apoptosis by arresting the cell cycle at the G2/M phase. Other observed effects included a decrease in the multi-drug resistance (MDR) carrier P-glycoprotein (P-gp) and TG2, a tumor survival factor. Augmented quantities of molecules promoting apoptosis such as Bak1 and caspase-3 and enhanced lipid peroxidation were also detected. Our findings in the cell model suggest that DHA can be further investigated as a natural compound to be used alongside doxorubicin in the treatment of breast cancer that is unresponsive to chemotherapy.

Paracrine secretion of IL8 by breast cancer stem cells promotes therapeutic resistance and metastasis of the bulk tumor cells

BACKGROUND

Breast tumors consist of heterogeneous cellular subpopulations that differ in molecular properties and functional attributes. Cancer stem cells (CSCs) play pivotal roles in cancer therapeutic failure and metastasis. However, it remains indeterminate how CSCs determine the progression of the bulk cancer cell population.

METHODS

Co-culture systems in vitro and co-implantation systems in vivo were designed to characterize the interactions between breast cancer stem cells (BCSCs) and bulk cancer cells. RNA sequencing was performed to study the functional and mechanistic implications of the BCSC secretome on bulk cancer cells. A cytokine antibody array was employed to screen the differentially secreted cytokines in the BCSC secretome. Tail vein injection metastatic models and orthotopic xenograft models were applied to study the therapeutic potential of targeting IL8.

RESULTS

We identified that the BCSC secretome potentiated estrogen receptor (ER) activity in the bulk cancer cell population. The BCSC secretome rendered the bulk cancer cell population resistant to anti-estrogen and CDK4/6 inhibitor therapy; as well as increased the metastatic burden attributable to bulk cancer cells. Screening of the BCSC secretome identified IL8 as a pivotal factor that potentiated ERα activity, endowed tamoxifen resistance and enhanced metastatic burden by regulation of bulk cancer cell behavior. Pharmacological inhibition of IL8 increased the efficacy of fulvestrant and/or palbociclib by reversing tamoxifen resistance and abrogated metastatic burden.

CONCLUSION

Taken together, this study delineates the mechanism by which BCSCs determine the therapeutic response and metastasis of bulk cancer cells; and thereby suggests potential therapeutic strategies to ameliorate breast cancer outcomes. Video Abstract.

Overcoming drug resistance with a docetaxel and disulfiram loaded pH-sensitive nanoparticle

Previous studies have demonstrated that breast cancer cells deploy a myriad array of strategies to thwart the activity of anticancer drugs like docetaxel (DTX), including acquired drug resistance due to overexpression of drug-efflux pumps like P-glycoprotein (P-gp) and innate drug resistance by cancer stem cells (CSCs). As disulfiram (DSF) can inhibit both P-gp and CSCs, we hypothesized that co-treatment of DTX and DSF could sensitize the drug-resistant breast cancer cells. To deliver a fixed dose ratio of DTX and DSF targeted to the tumor, a tumor extracellular pH-responsive nanoparticle (NP) was developed using a histidine-conjugated star-shaped PLGA with TPGS surface decoration ([DD]NpH-T). By releasing the encapsulated drugs in the tumor microenvironment, pH-sensitive NPs can overcome the tumor stroma-based resistance against nanomedicines. In in-vitro studies, [DD]NpH-T exhibited increased drug release at pH 6.8, improved penetration in a 3D tumor spheroid, reduced serum protein adsorption, and enhanced cytotoxic efficacy against both innate and acquired DTX-resistant breast cancer cells. In in-vivo studies, a significant increase in plasma AUC and tumor drug delivery was observed with [DD]NpH-T, which resulted in an enhanced in-vivo anti-tumor efficacy against a mouse orthotopic breast cancer, with a significantly increased intratumoral ROS and apoptosis, while decreasing P-gp expression and prevention of lung metastasis. Altogether, the current study demonstrated that the DTX and DSF combination could effectively target multiple drug-resistance pathways in-vitro, and the in-vivo delivery of this drug combination using TPGS-decorated pH-sensitive NPs could increase tumor accumulation, resulting in improved anti-tumor efficacy.

Metabolomics by NMR Combined with Machine Learning to Predict Neoadjuvant Chemotherapy Response for Breast Cancer

Simple Summary

Neoadjuvant chemotherapy (NACT) is offered to breast cancer (BC) patients to downstage the disease. However, some patients may not respond to NACT, being resistant. We used the serum metabolic profile by Nuclear Magnetic Resonance (NMR) combined with disease characteristics to differentiate between sensitive and resistant BC patients. We obtained accuracy above 80% for the response prediction and showcased how NMR can substantially enhance the prediction of response to NACT.

Abstract

Neoadjuvant chemotherapy (NACT) is offered to patients with operable or inoperable breast cancer (BC) to downstage the disease. Clinical responses to NACT may vary depending on a few known clinical and biological features, but the diversity of responses to NACT is not fully understood. In this study, 80 women had their metabolite profiles of pre-treatment sera analyzed for potential NACT response biomarker candidates in combination with immunohistochemical parameters using Nuclear Magnetic Resonance (NMR). Sixty-four percent of the patients were resistant to chemotherapy. NMR, hormonal receptors (HR), human epidermal growth factor receptor 2 (HER2), and the nuclear protein Ki67 were combined through machine learning (ML) to predict the response to NACT. Metabolites such as leucine, formate, valine, and proline, along with hormone receptor status, were discriminants of response to NACT. The glyoxylate and dicarboxylate metabolism was found to be involved in the resistance to NACT. We obtained an accuracy in excess of 80% for the prediction of response to NACT combining metabolomic and tumor profile data. Our results suggest that NMR data can substantially enhance the prediction of response to NACT when used in combination with already known response prediction factors.

Exosome-mediated transfer of circHIPK3 promotes trastuzumab chemoresistance in breast cancer

Breast cancer (BC) remains a public health dilemma in the world and it is one of the leading causes of death among women. Trastuzumab is a kind of commonly-used drugs in the treatment of BC, which especially can provide substantial benefits for HER2-positive BC. However, its long-time usage results in the emergence of resistance, which cuts down its efficacy in BC and leads to a poorer overall survival rate. Hence, the attempt of this study was to investigate how the drug resistance was enhanced. It has been identified that circHIPK3 could act as an oncogene in BC and promoted cell development through and a series of function assays. However, the underlying regulatory mechanism of circHIPK3 is not well established in trastuzumab resistance to date. Furthermore, we found the functional role of exosomes in trastuzumab chemoresistance and discovered that exosomes derived from trastuzumab-resistant cells could enhance the drug resistance of trastuzumab-sensitive cells. In last decades, competing endogenous RNA (ceRNA) has been a hot topic to investigate potential mechanism in cells. We subsequently performed mechanism experiments and rescue assays to verify circHIPK3 acted as a ceRNA in BC cells. In conclusion, we uncovered the regulatory mechanism by which exosome-transmitted circHIPK3 could promote trastuzumab chemoresistance of drug-sensitive BC cells.

Overexpression of NF-kB as a predictor of neoadjuvant chemotherapy response in breast cancer

BACKGROUND

Cancer cells can defend themselves against apoptosis by activating NF-κB. Nuclear factor-kappa B (NF-κB) activity has also been associated with chemotherapy resistance.

OBJECTIVE

We aimed to investigate the relationship between NF-κB expression and intrinsic subtypes and anthracycline-based neoadjuvant chemotherapy responses in patients with locally advanced breast cancer.

METHODS

This prospective cohort study examined NF-κB expression and intrinsic subtypes of breast cancer tissue using immunohistochemistry (IHC). We conducted descriptive statistical analyses as well as survival analyses.

RESULTS

 The study sample was 63 patients, of which 21 cases (33.33%) were responsive to neoadjuvant chemotherapy, and 42 cases (66.7%) were non-responsive. There is a significant relationship between negative ER, negative PR, grading, and high Ki67 expression with NF-κB overexpression (p < 0.05). No significant relationship was found between intrinsic subtypes and HER2 with NF-κB expression (p > 0.05). A significant relationship was found between NF-κB expression and responsive chemotherapy results (p < 0.01).

CONCLUSION

In locally advanced breast cancer, there is a correlation between NF-B expression and response to anthracycline-based neoadjuvant chemotherapy. Patients who express NF-KB have a better response to chemotherapy than those who overexpress NF-kB.

High FAS expression correlates with a better prognosis and efficacy of taxanes and target regents in breast cancer

BACKGROUND

FAS can serve as both an oncogene and a suppresser in different malignancies, and the prognostic value of FAS remains controversial.

METHODS

The Oncomine database, KM-Plotter and bc-GenExMiner platform were adopted to analyze the prognostic value of FAS in breast cancer. Breast cancer tissue microarrays were further used to verify these data. The Cell Miner Tool was used to predict the value of FAS mRNA expression in predicting the efficacies of clinical drugs.

RESULTS

We found that both FAS mRNA and protein expression level significantly reduced in breast carcinoma. In addition, high FAS expression indicates a better metastatic relapse-free survival. Interestingly, FAS was associated with a better prognosis in different subtypes of breast cancer patients, namely, only in grade II and III, lymph nodal positive or p53 wild-type patients. The data from the Cell Miner Tool revealed that FAS mRNA expression was correlated with the efficacy of the first-line chemotherapeutic taxane agents and target drugs including olaparib and everolimus.

CONCLUSIONS

FAS expression correlates with a better prognosis in breast cancer and may provide an effective clinical strategy to predict the sensitivity of taxanes and targeted drugs.

Emerging strategies for treating metastasis

The systemic spread of tumor cells is the ultimate cause of the majority of deaths from cancer, yet few successful therapeutic strategies have emerged to specifically target metastasis. Here we discuss recent advances in our understanding of tumor-intrinsic pathways driving metastatic colonization and therapeutic resistance, as well as immune activating strategies to target metastatic disease. We focus on therapeutically exploitable mechanisms, promising strategies in preclinical and clinical development, and emerging areas with potential to become innovative treatments.

The relationship between NFKB, HER2, ER expression and anthracycline -based neoadjuvan chemotherapy response in local advanced stadium breast cancer: A cohort study in Eastern Indonesia

Introduction

Neoadjuvant chemotherapy has become the standard form of treatment for locally advanced breast cancer. Chemoresistence is a problem that limits the effectiveness of chemotherapy. Therefore, predictive biomarkers are needed to choose the appropriate chemotherapy to the right patient. The role of NF-кb expression as a predictive biomarker of neoadjuvant chemotherapy response needs to be investigated in patients with locally advanced breast cancer who are treated with a regimen of cyclophosphamide-doxorubicin-5FU (CAF).

Methods

This observational study used the prospective cohort method to examine 62 samples. CAF was administered at 3-week intervals for 3 cycles of chemotherapy. The data utilized in this study include the positive and negative expression of NF-κB, ER, and HER2 overexpression. The cases were divided into groups that were responsive and non-responsive to the neoadjuvant chemotherapy.

Results

The average age in the youngest group was 26 years, and that in the oldest was 66 years. The highest age group was subjects in their 50s, which had 26 cases (41.9%). The majority of the cases were moderate grade with 38 cases (61.3%). The percentage of responsive subjects was higher in the groups with negative NF-κB expression (82.5%), positive HER2 status (85.7%), and negative ER status (71.9%). It was found that 37 cases (59.7%) were responsive to CAF, while 25 cases (40.3%) were non-responsive. There was a significant relationship between NF-κB expression and chemotherapy response (p < 0.05), and the percentage of responsive subjects was higher among those with negative NF-κB expression (82.5%) than positive NF-κB expression (18.2%).

Conclusion

NF-κB expression, ER status, and HER2 have a significant relationship with the response to anthracycline-based neoadjuvant chemotherapy for local advanced breast cancer, and NF-κB expression has the most significant relationship with the chemotherapy response. Therefore, NF-κB expression should be considered as a predictive biomarker for the response to CAF regimens.

Breaking the barrier: an osmium photosensitizer with unprecedented hypoxic phototoxicity for real world photodynamic therapy

Hypoxia presents a two-fold challenge in the treatment of cancer, as low oxygen conditions induce biological changes that make malignant tissues simultaneously more aggressive and less susceptible to standard chemotherapy. This paper reports the first metal-based photosensitizer that approaches the ideal properties for a phototherapy agent. The Os(phen)2-based scaffold was combined with a series of IP-nT ligands, where phen = 1,10-phenanthroline and IP-nT = imidazo[4,5-f][1,10]phenanthroline tethered to n = 0-4 thiophene rings. Os-4T (n = 4) emerged as the most promising complex in the series, with picomolar activity and a phototherapeutic index (PI) exceeding 106 in normoxia. The photosensitizer exhibited an unprecedented PI > 90 (EC50 = 0.651 μM) in hypoxia (1% O2) with visible and green light, and a PI > 70 with red light. Os-4T was also active with 733 nm near-infrared light (EC50 = 0.803 μM, PI = 77) under normoxia. Both computation and spectroscopic studies confirmed a switch in the nature of the lowest-lying triplet excited state from triplet metal-to-ligand charge transfer (3MLCT) to intraligand charge transfer (3ILCT) at n = 3, with a lower energy and longer lifetime for n = 4. All compounds in the series were relatively nontoxic in the dark but became increasingly phototoxic with additional thiophenes. These normoxic and hypoxic activities are the largest reported to date, demonstrating the utility of osmium for phototherapy applications. Moreover, Os-4T had a maximum tolerated dose (MTD) in mice that was >200 mg kg-1, which positions this photosensitizer as an excellent candidate for in vivo applications.

Transcription Factors in Cancer Development and Therapy

Cancer is a multi-step process and requires constitutive expression/activation of transcription factors (TFs) for growth and survival. Many of the TFs reported so far are critical for carcinogenesis. These include pro-inflammatory TFs, hypoxia-inducible factors (HIFs), cell proliferation and epithelial-mesenchymal transition (EMT)-controlling TFs, pluripotency TFs upregulated in cancer stem-like cells, and the nuclear receptors (NRs). Some of those, including HIFs, Myc, ETS-1, and β-catenin, are multifunctional and may regulate multiple other TFs involved in various pro-oncogenic events, including proliferation, survival, metabolism, invasion, and metastasis. High expression of some TFs is also correlated with poor prognosis and chemoresistance, constituting a significant challenge in cancer treatment. Considering the pivotal role of TFs in cancer, there is an urgent need to develop strategies targeting them. Targeting TFs, in combination with other chemotherapeutics, could emerge as a better strategy to target cancer. So far, targeting NRs have shown promising results in improving survival. In this review, we provide a comprehensive overview of the TFs that play a central role in cancer progression, which could be potential therapeutic candidates for developing specific inhibitors. Here, we also discuss the efforts made to target some of those TFs, including NRs.

Transcription Factors in Cancer Development and Therapy

Cancer is a multi-step process and requires constitutive expression/activation of transcription factors (TFs) for growth and survival. Many of the TFs reported so far are critical for carcinogenesis. These include pro-inflammatory TFs, hypoxia-inducible factors (HIFs), cell proliferation and epithelial-mesenchymal transition (EMT)-controlling TFs, pluripotency TFs upregulated in cancer stem-like cells, and the nuclear receptors (NRs). Some of those, including HIFs, Myc, ETS-1, and β-catenin, are multifunctional and may regulate multiple other TFs involved in various pro-oncogenic events, including proliferation, survival, metabolism, invasion, and metastasis. High expression of some TFs is also correlated with poor prognosis and chemoresistance, constituting a significant challenge in cancer treatment. Considering the pivotal role of TFs in cancer, there is an urgent need to develop strategies targeting them. Targeting TFs, in combination with other chemotherapeutics, could emerge as a better strategy to target cancer. So far, targeting NRs have shown promising results in improving survival. In this review, we provide a comprehensive overview of the TFs that play a central role in cancer progression, which could be potential therapeutic candidates for developing specific inhibitors. Here, we also discuss the efforts made to target some of those TFs, including NRs.

The matrix metalloproteinase 7 (MMP7) links Hsp90 chaperone with acquired drug resistance and tumor metastasis

BACKGROUND

Cancer emergence is associated with a series of cellular transformations that include acquired drug resistance followed by tumor metastasis. Matrix metalloproteinases (MMPs) and Hsp90 chaperone are implicated in tumor progression, however, they are not studied in the context of drug resistance.

AIMS

In the present study, we aimed at understanding the cross-talk between acquired drug resistance and tumor progression, linking MMP7 and Hsp90.

METHODS AND RESULTS

We have developed an in vitro model system for acquired drug resistance and studied the correlation between MMP7 and Hsp90. We demonstrate that enhanced drug efflux activity correlates with the induced expression and activity of MMP7, and enhanced metastatic potential of cells, however, in Hsp90-dependent manner. The MMP7 overexpression alone could enhance the drug efflux activity marginally, and metastasis significantly. However, challenging these cells with 17AAG has significantly increased the drug efflux activity and, in contrast, decreased the metastatic potential. Evaluating our in vitro findings in mice xenografts revealed that MMP7 overexpression facilitates altered homing properties. However, these cells, in response to 17AAG treatment, exhibited increased localized tumor growth but decreased tumor metastasis.

CONCLUSION

We demonstrated a cross-talk between Hsp90 and MMP7 in regulating the acquired drug resistance and tumor progression. Our findings provide novel insights on targeting drug resistant-tumors.

Hsp90 facilitates acquired drug resistance of tumor cells through cholesterol modulation however independent of tumor progression

Acquired multidrug resistance of cancer cells challenges the chemotherapeutic interventions. To understand the role of molecular chaperone, Hsp90 in drug adapted tumor cells, we have used in vitro drug adapted epidermoid tumor cells as a model system. We found that chemotherapeutic drug adaptation of tumor cells is mediated by induced activities of both Hsp90 and P-glycoprotein (P-gp). Although the high-affinity conformation of Hsp90 has correlated with the enhanced drug efflux activity, we did not observe a direct interaction between P-gp and Hsp90. The enrichment of P-gp and Hsp90 at the cholesterol-rich membrane microdomains is found obligatory for enhanced drug efflux activity. Since inhibition of cholesterol biosynthesis is not interfering with the drug efflux activity, it is presumed that the net cholesterol redistribution mediated by Hsp90 regulates the enhanced drug efflux activity. Our in vitro cholesterol and Hsp90 interaction studies have furthered our presumption that Hsp90 facilitates cholesterol redistribution. The drug adapted cells though exhibited anti-proliferative and anti-tumor effects in response to 17AAG treatment, drug treatment has also enhanced the drug efflux activity. Our findings suggest that drug efflux activity and metastatic potential of tumor cells are independently regulated by Hsp90 by distinct mechanisms. We expose the limitations imposed by Hsp90 inhibitors against multidrug resistant tumor cells.

Emerging Roles of C-Myc in Cancer Stem Cell-Related Signaling and Resistance to Cancer Chemotherapy: A Potential Therapeutic Target Against Colorectal Cancer

Myc is a nuclear transcription factor that mainly regulates cell growth, cell cycle, metabolism, and survival. Myc family proteins contain c-Myc, n-Myc, and l-Myc. Among them, c-Myc can become a promising therapeutic target molecule in cancer. Cancer stem cells (CSCs) are known to be responsible for the therapeutic resistance. In the previous study, we demonstrated that c-Myc mediates drug resistance of colorectal CSCs using a patient-derived primary three-dimensional (3D) organoid culture. In this review, we mainly focus on the roles of c-Myc-related signaling in the regulation of CSCs, chemotherapy resistance, and colorectal cancer organoids. Finally, we introduce the various types of c-Myc inhibitors and propose the possibility of c-Myc as a therapeutic target against colorectal cancer.

Obatoclax, a BH3 Mimetic, Enhances Cisplatin-Induced Apoptosis and Decreases the Clonogenicity of Muscle Invasive Bladder Cancer Cells via Mechanisms That Involve the Inhibition of Pro-Survival Molecules as Well as Cell Cycle Regulators

Several studies by our group and others have determined that expression levels of Bcl-2 and/or Bcl-xL, pro-survival molecules which are associated with chemoresistance, are elevated in patients with muscle invasive bladder cancer (MI-BC). The goal of this study was to determine whether combining Obatoclax, a BH3 mimetic which inhibits pro-survival Bcl-2 family members, can improve responses to cisplatin chemotherapy, the standard of care treatment for MI-BC. Three MI-BC cell lines (T24, TCCSuP, 5637) were treated with Obatoclax alone or in combination with cisplatin and/or pre-miR-34a, a molecule which we have previously shown to inhibit MI-BC cell proliferation via decreasing Cdk6 expression. Proliferation, clonogenic, and apoptosis assays confirmed that Obatoclax can decrease cell proliferation and promote apoptosis in a dose-dependent manner. Combination treatment experiments identified Obatoclax + cisplatin as the most effective treatment. Immunoprecipitation and Western analyses indicate that, in addition to being able to inhibit Bcl-2 and Bcl-xL, Obatoclax can also decrease cyclin D1 and Cdk4/6 expression levels. This has not previously been reported. The combined data demonstrate that Obatoclax can inhibit cell proliferation, promote apoptosis, and significantly enhance the effectiveness of cisplatin in MI-BC cells via mechanisms that likely involve the inhibition of both pro-survival molecules and cell cycle regulators.

Aiding and Abetting: How the Tumor Microenvironment Protects Cancer from Chemotherapy

Disease recurrence following cancer therapy remains an intractable clinical problem and represents a major impediment to reducing the mortality attributable to malignant tumors. While research has traditionally focused on the cell-intrinsic mechanisms and mutations that render tumors refractory to both classical chemotherapeutics and targeted therapies, recent studies have begun to uncover myriad roles for the tumor microenvironment (TME) in modulating therapeutic efficacy. This work suggests that drug resistance is as much ecological as it is evolutionary. Specifically, cancers resident in organs throughout the body do not develop in isolation. Instead, tumor cells arise in the context of nonmalignant cellular components of a tissue. While the roles of these cell-extrinsic factors in cancer initiation and progression are well established, our understanding of the TME's influence on therapeutic outcome is in its infancy. Here, we focus on mechanisms by which neoplastic cells co-opt preexisting or treatment-induced signaling networks to survive chemotherapy.

Trefoil factors peptide-3 is associated with residual invasive breast carcinoma following neoadjuvant chemotherapy

Background

Breast carcinoma is the commonest cancer among UAE population and the most common cancer among females. Examination of the 5′ promoter regions of trefoil factor 3 (TFF3) gene has identified putative estrogen and progesterone receptor–DNA binding domains as direct response elements to estrogen and progesterone that are linked to breast functions or steroid regulation. The study was designed to determine the role of TFF3 in breast cancer chemoresistance with the aim of establishing TFF3 expression as a biomarker for drug resistance.

Methods

In total, 133 cases of breast carcinoma treated with neo-adjuvant therapy were collected. Tissue samples from pre-neoadjuvant therapy as well as tissues from post-neo-adjuvant therapy of those cases were collected and stained with immunohistochemistry for TFF3, Bcl2, BAX, cleaved caspase-3, AKT-1, NF kappa B and Ki-67.

Results

There was increased expression of TFF3 in residual invasive carcinoma cells. There was a significant correlation between the expression of TFF3 in breast carcinoma cells and response to neoadjuvant chemotherapy (p = 0.0165). There was significant co-expression of TFF3 with AKT1 (p = 0.0365), BCl2 (p = 0.0152), and NF Kappa-B (p = 0.0243) in breast carcinoma cases with residual carcinoma following neoadjuvant therapy which support the role of TFF3 in chemoresistance.

Conclusion

The expression of TFF3 is significantly associated with residual breast carcinoma following neoadjuvant chemotherapy suggesting its expression is associated with increased resistance to chemotherapy. This is supported by its co-expression with antiapoptotic proteins; BCl2, AKT1 and NF Kappa-B in residual breast carcinoma cells and very low proliferating index and apoptotic bodies in residual tumors.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5316-y) contains supplementary material, which is available to authorized users.

Development and evaluation of a CEACAM6-targeting theranostic nanomedicine for photoacoustic-based diagnosis and chemotherapy of metastatic cancer

Metastasis is the leading cause of cancer-related deaths. A number of chemotherapeutic and early diagnosis strategies, including nanomedicine, have been developed to target metastatic tumor cells. However, simultaneous inhibition and imaging of metastasis is yet to be fully achieved. Methods: To overcome this limitation, we have developed human serum albumin-based nanoparticles (tHSA-NPs) with photoacoustic imaging capability, which target carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6). CEACAM6 is highly expressed in metastatic anoikis-resistant tumor cells. Results:In vitro, the CEACAM6-targeting tHSA-NPs efficiently targeted CEACAM6-overexpressing metastatic anoikis-resistant tumor cells. In vivo, CEACAM6-targeting tHSA-NPs administered intravenously to BALB/c nude mice efficiently inhibited lung metastasis in circulating anoikis-resistant tumor cells compared to the controls. In addition, anoikis-resistant tumor cells can be successfully detected by photoacoustic imaging, both in vitro and in vivo, using the intrinsic indocyanine green-binding affinity of albumin. Conclusion: In summary, the CEACAM6-targeting albumin-based nanoparticles allowed the delivery of drugs and photoacoustic imaging to metastatic anoikis-resistant tumor cells in vitro and in vivo. Based on the expression of CEACAM6 in a variety of tumors, CEACAM6-targeting nanomedicine might be used to target various types of metastatic tumor cells.

Editor’s Pick: Pyruvate Kinase and Gastric Cancer: A Potential Marker

Gastric cancer is the second most common cause of cancer-related deaths worldwide, and the 5-year overall survival rate for advanced gastric cancer is ≤25%. Metabolism is a critical process for maintaining growth and other functions in cancer cells; in these cells, the metabolic process shifts from oxidative phosphorylation to aerobic glycolysis and the expression of pyruvate kinase (PK) splice isoform M2 (PKM2) is upregulated. A PubMed search focussing on PK in gastric cancer was conducted and 32 articles were initially collected; 12 articles were subsequently excluded from this review. PKM2 is responsible for tumour growth and invasion and correlates with short survival times and cancer differentiation. Pyruvate dehydrogenase kinase 1 is associated with cell proliferation, lymph node metastasis, and invasion. Measurement of PKM2 or pyruvate dehydrogenase kinase 1 in the blood or stools could be a good marker for gastric cancer in combination with the glycoprotein CA72-4. The review arose from the need for new biomarkers in the management of gastric cancer and had the primary objective of determining whether PK could be used as a marker to diagnose and monitor gastric cancer.

A Metabolomic Approach to Predict Breast Cancer Behavior and Chemotherapy Response

Although the classification of breast carcinomas into molecular or immunohistochemical subtypes has contributed to a better categorization of women into different therapeutic regimens, breast cancer nevertheless still progresses or recurs in a remarkable number of patients. Identifying women who would benefit from chemotherapy could potentially increase treatment effectiveness, which has important implications for long-term survival. Metabolomic analyses of fluids and tissues from cancer patients improve our knowledge of the reprogramming of metabolic pathways involved in resistance to chemotherapy. This review evaluates how recent metabolomic approaches have contributed to understanding the relationship between breast cancer and the acquisition of resistance. We focus on the advantages and challenges of cancer treatment and the use of new strategies in clinical care, which helps us comprehend drug resistance and predict responses to treatment.

Bcl-2 Antiapoptotic Family Proteins and Chemoresistance in Cancer

Cancer is a daunting global problem confronting the world's population. The most frequent therapeutic approaches include surgery, chemotherapy, radiotherapy, and more recently immunotherapy. In the case of chemotherapy, patients ultimately develop resistance to both single and multiple chemotherapeutic agents, which can culminate in metastatic disease which is a major cause of patient death from solid tumors. Chemoresistance, a primary cause of treatment failure, is attributed to multiple factors including decreased drug accumulation, reduced drug-target interactions, increased populations of cancer stem cells, enhanced autophagy activity, and reduced apoptosis in cancer cells. Reprogramming tumor cells to undergo drug-induced apoptosis provides a promising and powerful strategy for treating resistant and recurrent neoplastic diseases. This can be achieved by downregulating dysregulated antiapoptotic factors or activation of proapoptotic factors in tumor cells. A major target of dysregulation in cancer cells that can occur during chemoresistance involves altered expression of Bcl-2 family members. Bcl-2 antiapoptotic molecules (Bcl-2, Bcl-xL, and Mcl-1) are frequently upregulated in acquired chemoresistant cancer cells, which block drug-induced apoptosis. We presently overview the potential role of Bcl-2 antiapoptotic proteins in the development of cancer chemoresistance and overview the clinical approaches that use Bcl-2 inhibitors to restore cell death in chemoresistant and recurrent tumors.

Histone code and long non-coding RNAs (lncRNAs) aberrations in lung cancer: implications in the therapy response

Respiratory diseases hold several genome, epigenome, and transcriptional aberrations as a cause of the accumulated damage promoted by, among others, environmental risk factors. Such aberrations can also come about as an adaptive response when faced with therapeutic oncological drugs. In epigenetic terms, aberrations in DNA methylation patterns, histone code marks balance, and/or chromatin-remodeling complexes recruitment, among Polycomb Repressive Complex-2 (PRC2) versus Trithorax (TRX) Activator Complex, have been proposed to be affected by several previously characterized functional long non-coding RNAs (lncRNAs). Such molecules are involved in modulating and/or controlling lung cancer epigenome and genome expression, as well as in malignancy and clinical progression in lung cancer. Several recent reports have described diverse epigenetic modifications in lung cancer cells and solid tumors, among others genomic DNA methylation and post-translational modifications (PTMs) on histone tails, as well as lncRNAs patterns and levels of expression. However, few systematic approaches have attempted to demonstrate a biological function and clinical association, aiming to improve therapeutic decisions in basic research and lung clinical oncology. A widely used example is the lncRNA HOTAIR and its functional histone mark H3K27me3, which is directly associated to the PRC2; however, few systematic pieces of solid evidence have been experimentally performed, conducted and/or validated to predict lung oncological therapeutic efficacy. Recent evidence suggests that chromatin-remodeling complexes accompanied by lncRNAs profiles are involved in several comprehensive lung carcinoma clinical parameters, including histopathology progression, prognosis, and/or responsiveness to unique or combined oncological therapies. The present manuscript offers a systematic revision of the current knowledge about the major epigenetic aberrations represented by changes in histone PTMs and lncRNAs expression levels and patterns in human lung carcinomas in cancer drug-based treatments, as an important comprehensive knowledge focusing on better oncological therapies. In addition, a new future direction must be refocusing on several gene target therapies, mainly on pharmaceutical EGFR-TKIs compounds, widely applied in lung cancer, currently the leading cause of death by malignant diseases.

Chemoresistance in cancer cells: exosomes as potential regulators of therapeutic tumor heterogeneity

Drug resistance in cancer cells remains a fundamental challenge. Be it nontargeted or targeted drugs, the presence of intrinsic or acquired cancer cell resistance remains a great obstacle in chemotherapy. Conventionally, a spectrum of cellular mechanisms defines drug resistance including overexpression of antiapoptotic proteins and drug efflux pumps, mutations in target and synergistic activation of prosurvival pathways in tumor cells. In addition to these well-studied routes, exosome-induced chemoresistance is emerging as a novel mechanism. Mechanistically, exosomes impart resistance by direct drug export, transport of drug efflux pumps and miRNAs exchange among cells. Moreover, exosome signaling creates ‘therapeutic tumor heterogeneity’ and favorably condition tumor microenvironment. Here, we discuss exosomes’ role in chemoresistance and possibilities of developing novel therapeutic strategies.

The Dual Roles of MYC in Genomic Instability and Cancer Chemoresistance

Cancer is associated with genomic instability and aging. Genomic instability stimulates tumorigenesis, whereas deregulation of oncogenes accelerates DNA replication and increases genomic instability. It is therefore reasonable to assume a positive feedback loop between genomic instability and oncogenic stress. Consistent with this premise, overexpression of the MYC transcription factor increases the phosphorylation of serine 139 in histone H2AX (member X of the core histone H2A family), which forms so-called γH2AX, the most widely recognized surrogate biomarker of double-stranded DNA breaks (DSBs). Paradoxically, oncogenic MYC can also promote the resistance of cancer cells to chemotherapeutic DNA-damaging agents such as cisplatin, clearly implying an antagonistic role of MYC in genomic instability. In this review, we summarize the underlying mechanisms of the conflicting functions of MYC in genomic instability and discuss when and how the oncoprotein exerts the contradictory roles in induction of DSBs and protection of cancer-cell genomes.

Regulation of Mucin 1 and multidrug resistance protein 1 by honokiol enhances the efficacy of doxorubicin-mediated growth suppression in mammary carcinoma cells

Understanding the link between chemoresistance and cancer progression may identify future targeted therapy for breast cancer. One of the mechanisms by which chemoresistance is attained in cancer cells is mediated through the expression of multidrug resistance proteins (MRPs). Acquiring drug resistance has been correlated to the emergence of metastasis, accounting for the progression of the disease. One of the diagnostic markers of metastatic progression is the overexpression of a transmembrane protein called Mucin 1 (MUC1) which has been implicated in reduced survival rate. The objective of this study was to understand the relationship between MUC1 and MRP1 using natural phenolic compound isolated from Magnolia grandiflora, honokiol, in mammary carcinoma cells. We provide evidence that honokiol suppresses the expression level of MUC1 and MRP1 in mammary carcinoma cells. In a time-dependent manner, honokiol-mediated reduction of MUC1 is followed by a reduction of MRP1 expression in the breast cancer cells. Additionally, silencing MUC1 suppresses the expression level of MRP1 and enhances the efficacy of doxorubicin, an MRP1 substrate. Taken together, these findings suggest MUC1 regulates the expression of MRP1 and provides a direct link between cancer progression and chemoresistance in mammary carcinoma cells.

Combining ABCG2 Inhibitors with IMMU-132, an Anti-Trop-2 Antibody Conjugate of SN-38, Overcomes Resistance to SN-38 in Breast and Gastric Cancers

Sacituzumab govitecan (IMMU-132), an SN-38-conjugated antibody-drug conjugate, is showing promising therapeutic results in a phase I/II trial of patients with advanced Trop-2-expressing, metastatic, solid cancers. As members of the ATP-binding cassette (ABC) transporters confer chemotherapy resistance by active drug efflux, which is a frequent cause of treatment failure, we explored the use of known inhibitors of ABC transporters for improving the therapeutic efficacy of IMMU-132 by overcoming SN-38 resistance. Two human tumor cell lines made resistant to SN-38, MDA-MB-231-S120 (human breast cancer) and NCI-N87-S120 (human gastric cancer), were established by continuous exposure of the parental cells to stepwise increased concentrations of SN-38 and analyzed by flow cytometry for functional activities of ABCG2 and ABCB1, immunoblotting and qRT-PCR for the expression of ABCG2 at both protein and mRNA levels, and MTS assays for the potency of SN-38 alone or in combination with a modulator of ABC transporters. MDA-MB-231-S120 and NCI-N87-S120 displayed reduced sensitivity to SN-38 in vitro, with IC50 values approximately 50-fold higher than parental MDA-MB-231 and NCI-N87 cells. The increase in drug resistance of both S120 cell populations is associated with the expression of functional ABCG2, but not ABCB1. Importantly, treatment of both S120 sublines with known ABCG2 inhibitors (fumitremorgin C, Ko143, and YHO-13351) restored toxicity of SN-38, and the combination of YHO-13351 with IMMU-132 increased the median survival of mice bearing NCI-N87-S120 xenografts. These results provide a rationale for combination therapy of IMMU-132 and inhibitors of ABC transporters, such as YHO-13351. Mol Cancer Ther; 15(8); 1910-9. ©2016 AACR.

Deficiency of mitochondrial modulator MCJ promotes chemoresistance in breast cancer

Despite major advances in early detection and prognosis, chemotherapy resistance is a major hurdle in the battle against breast cancer. Identifying predictive markers and understanding the mechanisms are key steps to overcoming chemoresistance. Methylation-controlled J protein (MCJ, also known as DNAJC15) is a negative regulator of mitochondrial respiration and has been associated with chemotherapeutic drug sensitivity in cancer cell lines. Here we show, in a retrospective study of a large cohort of breast cancer patients, that low MCJ expression in breast tumors predicts high risk of relapse in patients treated with chemotherapy; however, MCJ expression does not correlate with response to endocrine therapy. In a prospective study in breast cancer patients undergoing neoadjuvant therapy, low MCJ expression also correlates with poor clinical response to chemotherapy and decreased disease-free survival. Using MCJ-deficient mice, we demonstrate that lack of MCJ is sufficient to induce mammary tumor chemoresistance in vivo. Thus, loss of expression of this endogenous mitochondrial modulator in breast cancer promotes the development of chemoresistance.

Up-regulation of HB-EGF by the COX-2/PGE2 signaling associates with the cisplatin resistance and tumor recurrence of advanced HNSCC

OBJECTIVES

When treating advanced HNSCC, a cisplatin-based systemic regimen benefit patient survival. However, chemoresistance will greatly reduce the effectiveness of this approach. The identification of molecules that contribute to cisplatin resistance may potentially improve the survival. Both HB-EGF and COX-2 have been reported to increase cisplatin-resistance. Here, we have focused on the regulation of HB-EGF/COX-2 and their roles in cisplatin resistance.

MATERIALS AND METHODS

IHC staining was used to measure the expression levels of HB-EGF and COX-2 on the tissue microarray from 43 tissue samples of patients with advanced HNSCC. siRNA, western blot and qRT-PCR were used to dissect the regulation between EGF, Akt, COX-2, PGE2, and cisplatin sensitivity. The correlation between HB-EGF, COX2 and HNSCC progression was analyzed by the receiver operating characteristic (ROC) curve and Kaplan-Meier disease free survival.

RESULTS

Patients of advanced HNSCC patients with increased HB-EGF and COX-2 expression have higher tumor recurrent rates that was related to cisplatin resistance. The resistance was mediated via an increased expression of HB-EGF and COX-2. The activation of Akt by either EGF or areca nut extract were able to upregulate COX-2, which would increase the expression of HB-EGF in a PGE2 dependent manner. Inhibition and knockdown of COX-2 resulted in a decrease in HB-EGF. In the tissue samples from HNSCC patients, there was a significant positive correlation between the expression of COX-2 and HB-EGF.

CONCLUSION

Our results suggested that COX-2 and HB-EGF are important in development of HNSCC cisplatin resistance. These findings may help the development of new strategies for overcoming cisplatin resistance.

Oncogenic MicroRNAs: Key Players in Malignant Transformation

MicroRNAs (miRNAs) represent a class of non-coding RNAs that exert pivotal roles in the regulation of gene expression at the post-transcriptional level. MiRNAs are involved in many biological processes and slight modulations in their expression have been correlated with the occurrence of different diseases. In particular, alterations in the expression of miRNAs with oncogenic or tumor suppressor functions have been associated with carcinogenesis, malignant transformation, metastasis and response to anticancer treatments. This review will mainly focus on oncogenic miRNAs whose aberrant expression leads to malignancy.

NDRG1 promotes the multidrug resistance of neuroblastoma cells with upregulated expression of drug resistant proteins

BACKGROUND

Resistance to chemotherapeutic drugs and recurrence are two major causes of poor prognosis in many tumors including neuroblastoma. This study aimed to investigate the effect of the elevated intracellular NDRG1 expression on drug resistance of human neuroblastoma cells to chemotherapy, for exploring novel approaches for biotherapy of neuroblastoma.

METHODS

Human neuroblastoma KP-N-Ns cell lines were transfected with the lentivirus vector containing human NDRG1 cDNA, with empty vector-transfected or blank cells as controls. Transfection status was confirmed under fluorescence microscope, while PCR assay and western blot analysis were performed to determine the expression changes. MTT and TUNEL assays were used to detect the resistance of the cells to anticancer drugs, including vincristine, cyclophosphamide and so on. Additionally, the expression of drug resistant proteins was detected.

RESULTS

Stable lentiviral transfection cell line was successfully established with significantly upregulated NDRG1 expression. MTT assay revealed greater cell growth under NDRG1 overexpression with drugs stimulation, as compared to controls. TUNEL assay also showed less apoptosis of NDRG1 overexpressing cells than those of controls when exposed to these drugs, suggesting the increasing drug resistance through NDRG1 overexpression. Besides, the expression of MDR, LRP-1 and MRP-1 was also increased in NDRG1 overexpressing cells, implying NDRG1-mediated pathways in multidrug resistance of neuroblastoma.

CONCLUSION

NDRG1 could increase the resistance of neuroblastoma cells to chemotherapeutic drugs, with its positive regulation on drug resistant proteins. This study provided new insights for exploring the mechanism of the resistance to chemotherapeutic drugs and also novel approach for biotherapy in neuroblastoma.

Aldehyde dehydrogenase as a marker and functional mediator of metastasis in solid tumors

There is accumulating evidence indicating that aldehyde dehydrogenase (ALDH) activity selects for cancer cells with increased aggressiveness, capacity for sustained proliferation, and plasticity in primary tumors. However, emerging data also suggests an important mechanistic role for the ALDH family of isoenzymes in the metastatic activity of tumor cells. Recent studies indicate that ALDH correlates with either increased or decreased metastatic capacity in a cellular context-dependent manner. Importantly, it appears that different ALDH isoforms support increased metastatic capacity in different tumor types. This review assesses the potential of ALDH as biological marker and mechanistic mediator of metastasis in solid tumors. In many malignancies, most notably in breast cancer, ALDH activity and expression appears to be a promising marker and potential therapeutic target for treating metastasis in the clinical setting.

Mechanism study of peptide GMBP1 and its receptor GRP78 in modulating gastric cancer MDR by iTRAQ-based proteomic analysis

Background

Multidrug resistance (MDR) is a major obstacle to the treatment of gastric cancer (GC). Using a phage display approach, we previously obtained the peptide GMBP1, which specifically binds to the surface of MDR gastric cancer cells and is subsequently internalized. Furthermore, GMBP1 was shown to have the potential to reverse the MDR phenotype of gastric cancer cells, and GRP78 was identified as the receptor for this peptide. The present study aimed to investigate the mechanism of peptide GMBP1 and its receptor GRP78 in modulating gastric cancer MDR.

Methods

Fluorescence-activated cell sorting (FACS) and immunofluorescence staining were used to investigate the subcellular location and mechanism of GMBP1 internalization. iTRAQ was used to identify the MDR-associated downstream targets of GMBP1. Differentially expressed proteins were identified in GMBP1-treated compared to untreated SGC7901/ADR and SGC7901/VCR cells. GO and KEGG pathway analyses of the differentially expressed proteins revealed the interconnection of these proteins, the majority of which are involved in MDR. Two differentially expressed proteins were selected and validated by western blotting.

Results

GMBP1 and its receptor GRP78 were found to be localized in the cytoplasm of GC cells, and GRP78 can mediate the internalization of GMBP1 into MDR cells through the transferrin-related pathway. In total, 3,752 and 3,749 proteins were affected in GMBP1-treated SGC7901/ADR and SGC7901/VCR cells, respectively, involving 38 and 79 KEGG pathways. Two differentially expressed proteins, CTBP2 and EIF4E, were selected and validated by western blotting.

Conclusion

This study explored the role and downstream mechanism of GMBP1 in GC MDR, providing insight into the role of endoplasmic reticulum stress protein GRP78 in the MDR of cancer cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1361-3) contains supplementary material, which is available to authorized users.

Identification of miRNAs contributing to neuroblastoma chemoresistance

BACKGROUND

The emergence of the role of microRNAs (miRNAs) in exacerbating drug resistance of tumours is recently being highlighted as a crucial research field for future clinical management of drug resistant tumours. The purpose of this study was to identify dys-regulations in expression of individual and/or networks of miRNAs that may have direct effect on neuroblastoma (NB) drug resistance.

METHODS

Individual subcultures of chemosensitive SH-SY5Y and UKF-NB-3 cells were rendered chemoresistant to doxorubicin (SH-SY5Y, UKF-NB-3) or etoposide (SH-SY5Y). In each validated chemoresistance model, the parental and subcultured cell lines were analysed for miRNA expression profiling, using a high-throughput quantitative polymerase chain reaction (RT-qPCR) miRNA profiling platform for a total of 668 miRNAs.

RESULTS

A unique expression signature of miRNAs was found to be differentially expressed (higher than 2-fold change) within all three NB chemoresistance models. Four miRNAs were upregulated in the subcultured chemoresistant cell line. Three miRNAs were found to be downregulated in the chemoresistant cell lines for all models.

CONCLUSIONS

Based on the initial miRNA findings, this study elucidates the dys-regulation of four miRNAs in three separate NB chemoresistant cell line models, spanning two cell lines (SH-SY5Y and UKF-NB-3) and two chemotherapeutic agents (doxorubicin and etoposide). These miRNAs may thus be possibly linked to chemoresistance induction in NB. Such miRNAs are good candidates to be novel drug targets for future miRNA based therapies against aggressive tumours that are not responding to conventional chemotherapy.

Spatial heterogeneity in drug concentrations can facilitate the emergence of resistance to cancer therapy

Acquired resistance is one of the major barriers to successful cancer therapy. The development of resistance is commonly attributed to genetic heterogeneity. However, heterogeneity of drug penetration of the tumor microenvironment both on the microscopic level within solid tumors as well as on the macroscopic level across metastases may also contribute to acquired drug resistance. Here we use mathematical models to investigate the effect of drug heterogeneity on the probability of escape from treatment and the time to resistance. Specifically we address scenarios with sufficiently potent therapies that suppress growth of all preexisting genetic variants in the compartment with the highest possible drug concentration. To study the joint effect of drug heterogeneity, growth rate, and evolution of resistance, we analyze a multi-type stochastic branching process describing growth of cancer cells in multiple compartments with different drug concentrations and limited migration between compartments. We show that resistance is likely to arise first in the sanctuary compartment with poor drug penetrations and from there populate non-sanctuary compartments with high drug concentrations. Moreover, we show that only below a threshold rate of cell migration does spatial heterogeneity accelerate resistance evolution, otherwise deterring drug resistance with excessively high migration rates. Our results provide new insights into understanding why cancers tend to quickly become resistant, and that cell migration and the presence of sanctuary sites with little drug exposure are essential to this end.

Failure of cancer therapy is commonly attributed to the outgrowth of pre-existing resistant mutants already present prior to treatment, yet there is increasing evidence that the tumor microenvironment influences cell sensitivity to drugs and thus mediates the evolution of resistance during treatment. Here, we take into consideration important aspects of the tumor microenvironment, including spatial drug gradients and differential rates of cell proliferation. We show that the dependence of fitness on space together with cell migration facilitates the emergence of acquired resistance. Our analysis indicates that resistant cells that are selected for in compartments with high concentrations are likely to disseminate from sanctuary sites where they first acquire resistance preceding migration. The results suggest that it would be helpful to improve clinical outcomes by combining targeted therapy with anti-metastatic treatment aimed at constraining cell motility as well as by enhancing drug transportation and distribution throughout all metastatic compartments.

Paris saponin VII from trillium tschonoskii reverses multidrug resistance of adriamycin-resistant MCF-7/ADR cells via P-glycoprotein inhibition and apoptosis augmentation

ETHNOPHARMACOLOGICAL RELEVANCE

Saponins of several herbs are known to induce apoptosis in some cancer cells and are proposed to be promising modulators of drug resistance. In the present study, we extracted Paris saponin VII (PS VII), a kind of saponin, from Trillium tschonoskii Maxim. and observed its effect on adriamycin-resistant breast cancer cells.

MATERIALS AND METHODS

An adriamycin-resistant human breast cancer cell line, MCF-7/ADR cells were exposed to different concentrations of PS VII (0-100 μmol/L). Then, flow cytometric assays and a human apoptosis array were used to detect apoptotic cells and apoptosis related protein expression. P-glycoprotein levels and intracellular rhodamine 123 (RH-123) accumulations were measured to evaluate the expression and activity of P-glycoprotein.

RESULTS

PS VII dose dependently suppressed cell viability as well as triggered apoptosis and modulated drug resistance of MCF-7/ADR cells. Further results showed that PS VII treatment in MCF-7/ADR cells led to increased TNFR1, TRAIL R1/DR4, TRAIL R2/DR5, and FADD expression, and activation of PARP, caspase-8, and 3. In parallel to the alterations, P-glycoprotein expression and activity were also reduced.

CONCLUSION

These findings showed that PS VII might be an effective tumouristatic agent for the treatment of MDR breast cancer.

The paradigm of mutant p53-expressing cancer stem cells and drug resistance

It is well accepted that expression of mutant p53 involves the gain of oncogenic-specific activities accentuating the malignant phenotype. Depending on the specific cancer type, mutant p53 can contribute to either the early or the late events of the multiphase process underlying the transformation of a normal cell into a cancerous one. This multifactorial system is evident in ~50% of human cancers. Mutant p53 was shown to interfere with a variety of cellular functions that lead to augmented cell survival, cellular plasticity, aberration of DNA repair machinery and other effects. All these effects culminate in the acquisition of drug resistance often seen in cancer cells. Interestingly, drug resistance has also been suggested to be associated with cancer stem cells (CSCs), which reside within growing tumors. The notion that p53 plays a regulatory role in the life of stem cells, coupled with the observations that p53 mutations may contribute to the evolvement of CSCs makes it challenging to speculate that drug resistance and cancer recurrence are mediated by CSCs expressing mutant p53.

NFκB mediates cisplatin resistance through histone modifications in head and neck squamous cell carcinoma (HNSCC)

Cisplatin-based chemotherapy is the standard treatment of choice for head and neck squamous cell carcinoma (HNSCC). The efficiency of platinum-based therapies is directly influenced by the development of tumor resistance. Multiple signaling pathways have been linked to tumor resistance, including activation of nuclear factor kappa B (NFκB). We explore a novel mechanism by which NFκB drives HNSCC resistance through histone modifications. Post-translational modification of histones alters chromatin structure, facilitating the binding of nuclear factors that mediate DNA repair, transcription, and other processes. We found that chemoresistant HNSCC cells with active NFκB signaling respond to chemotherapy by reducing nuclear BRCA1 levels and by promoting histone deacetylation (chromatin compaction). Activation of this molecular signature resulted in impaired DNA damage repair, prolonged accumulation of histone γH2AX and increased genomic instability. We found that pharmacological induction of histone acetylation using HDAC inhibitors prevented NFκB-induced cisplatin resistance. Furthermore, silencing NFκB in HNSCC induced acetylation of tumor histones, resulting in reduced chemoresistance and increased cytotoxicity following cisplatin treatment. Collectively, these findings suggest that epigenetic modifications of HNSCC resulting from NFκB-induced histone modifications constitute a novel molecular mechanism responsible for chemoresistance in HNSCC. Therefore, targeted inhibition of HDAC may be used as a viable therapeutic strategy for disrupting tumor resistance caused by NFκB.

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Chemoresistant HNSCC cells have deacetylation of histones and active NFκB signaling.

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Histone deacetylation reduces BRCA1 levels and enhances genomic instability.

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Histone deacetylase (HDAC) inhibitors sensitize HNSCC to chemotherapy.

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NFκB signaling drives HNSCC chemoresistance by inducing histone deacetylation.

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NFκB inhibition results in histone acetylation and sensitizes HNSCC to chemotherapy.

Molecular Insights on Post-chemotherapy Retinoblastoma by Microarray Gene Expression Analysis

PURPOSE

Management of Retinoblastoma (RB), a pediatric ocular cancer is limited by drug-resistance and drug-dosage related side effects during chemotherapy. Molecular de-regulation in post-chemotherapy RB tumors was investigated.

MATERIALS AND METHODS

cDNA microarray analysis of two post-chemotherapy and one pre-chemotherapy RB tumor tissues was performed, followed by Principle Component Analysis, Gene ontology, Pathway Enrichment analysis and Biological Analysis Network (BAN) modeling. The drug modulation role of two significantly up-regulated genes (p≤0.05) - Ect2 (Epithelial-cell-transforming-sequence-2), and PRAME (preferentially-expressed-Antigen-in-Melanoma) was assessed by qRT-PCR, immunohistochemistry and cell viability assays.

RESULTS

Differential up-regulation of 1672 genes and down-regulation of 2538 genes was observed in RB tissues (relative to normal adult retina), while 1419 genes were commonly de-regulated between pre-chemotherapy and post- chemotherapy RB. Twenty one key gene ontology categories, pathways, biomarkers and phenotype groups harboring 250 differentially expressed genes were dys-regulated (EZH2, NCoR1, MYBL2, RB1, STAMN1, SYK, JAK1/2, STAT1/2, PLK2/4, BIRC5, LAMN1, Ect2, PRAME and ABCC4). Differential molecular expressions of PRAME and Ect2 in RB tumors with and without chemotherapy were analyzed. There was neither up- regulation of MRP1, nor any significant shift in chemotherapeutic IC50, in PRAME over-expressed versus non-transfected RB cells.

CONCLUSION

Cell cycle regulatory genes were dys-regulated post-chemotherapy. Ect2 gene was expressed in response to chemotherapy-induced stress. PRAME does not contribute to drug resistance in RB, yet its nuclear localization and BAN information, points to its possible regulatory role in RB.

The radio-sensitizing effect of xanthohumol is mediated by STAT3 and EGFR suppression in doxorubicin-resistant MCF-7 human breast cancer cells

BACKGROUND

Chemotherapeutic drug resistance remains a clinical obstacle in cancer management. Drug-resistant cancer cells usually exhibit cross-resistance to ionizing radiation, which has devastating consequences for patients. With a better understanding of the molecular mechanisms, it will be possible to develop strategies to overcome this cross-resistance and to increase therapeutic sensitivity.

METHODS

Natural and synthetic flavonoid compounds including xanthohumol, the principal flavonoid in hops, were investigated for its radio-sensitizing activity on human breast cancer MCF-7 and adriamycin-resistant MCF-7 (MCF-7/ADR) cells. Chemo-sensitizing or radio-sensitizing effect was analyzed by tetrazolium-based colorimetric assay and flow cytometry. Western blot analysis, confocal microscopy, gene silencing with siRNA transfection and luciferase reporter gene assay were performed to examine signaling molecule activation.

RESULTS

Among the tested flavonoid compounds, pretreatment of the cells with xanthohumol significantly sensitized MCF-7/ADR cells to the radiation treatment by inducing apoptosis. In MCF-7/ADR cells, treatment with xanthohumol alone or with gamma-rays significantly decreased levels of anti-apoptotic proteins. Multi-drug resistance 1 (MDR1), epidermal growth factor receptor (EGFR) and signal transducer and activator of transcription 3 (STAT3) expression levels in MCF-7/ADR cells were suppressed by xanthohumol treatment. In addition, xanthohumol treatment increased death receptor (DR)-4 and DR5 expression. The xanthohumol-induced changes of these resistance-related molecules in MCF-7/ADR cells were synergistically increased by gamma-ray treatment.

CONCLUSIONS

Xanthohumol restored sensitivity of MCF-7/ADR cells to doxorubicin and radiation therapies.

GENERAL SIGNIFICANCE

Our results suggest that xanthohumol may be a potent chemo- and radio-sensitizer, and its actions are mediated through STAT3 and EGFR inhibition.

Utilisation of nanoparticle technology in cancer chemoresistance

The implementation of cytotoxic chemotherapeutic drugs in the fight against cancer has played an invariably essential role for minimizing the extent of tumour progression and/or metastases in the patient and thus allowing for longer event free survival periods following chemotherapy. However, such therapeutics are nonspecific and bring with them dose-dependent cumulative adverse effects which can severely exacerbate patient suffering. In addition, the emergence of innate and/or acquired chemoresistance to the exposed cytotoxic agents undoubtedly serves to thwart effective clinical efficacy of chemotherapy in the cancer patient. The advent of nanotechnology has led to the development of a myriad of nanoparticle-based strategies with the specific goal to overcome such therapeutic hurdles in multiple cancer conditions. This paper aims to provide a brief overview and recollection of all the latest advances in the last few years concerning the application of nanoparticle technology to enhance the safe and effective delivery of chemotherapeutic agents to the tumour site, together with providing possible solutions to circumvent cancer chemoresistance in the clinical setting.

Treatment-induced secretion of WNT16B promotes tumor growth and acquired resistance to chemotherapy: implications for potential use of inhibitors in cancer treatment

Innate or acquired resistance to chemotherapy presents an important and predictable challenge in cancer therapy. Malignant tumors consist of both neoplastic and benign cells such as stromal fibroblasts, which can influence the tumor's response to cytotoxic therapy. In a recent article in Nature Medicine, Sun et al. show that increased expression of Wnt family member wingless-type MMTV integration site family member 16B (WNT16B) by the tumor microenvironment in response to cytotoxic damage and signals through the canonical Wnt pathway to promote tumor growth and chemotherapy resistance. Such findings outline a mechanism by which cytotoxic therapies given in cyclical doses can actually augment later treatment resistance and may open the door to new areas of research and to the development of new therapeutic targets that block the DNA damage response program.

The roles of Galectin-3 in autoimmunity and tumor progression

Galectin-3, a unique chimera-type member of the β-galactoside-binding soluble lectin family, is widely expressed in numerous cells. Here, we discuss the role of Galectin-3 in T-cell-mediated inflammatory (auto) immunity and tumor rejection by using Galectin-3-deficient mice and four disease models of human pathology: experimental autoimmune encephalomyelitis (EAE), Con-A-induced hepatitis, multiple low-dose streptozotocin-induced diabetes (MLD-STZ diabetes) and metastatic melanoma. We present evidence which suggest that Galectin-3 plays an important pro-inflammatory role in Con-A-induced hepatitis by promoting the activation of T lymphocytes, NKT cells and DCs, cytokine secretion, prevention of M2 macrophage polarization and apoptosis of mononuclear cells, and it leads to severe liver injury. In addition, experiments in Galectin-3-"knock-out" mice indicate that Galectin-3 is also involved in immune-mediated β-cell damage and is required for diabetogenesis in MLD-STZ model by promoting the expression of IFN-gamma, TNF-alpha, IL-17 and iNOS in immune and accessory effector cells. Next, our data demonstrated that Galectin-3 plays an important disease-exacerbating role in EAE through its multifunctional roles in preventing cell apoptosis and increasing IL-17 and IFN-gamma synthesis, but decreasing IL-10 production. Finally, based on our findings, we postulated that expression of Galectin-3 in the host may also facilitate melanoma metastasis by affecting tumor cell adhesion and modulating anti-melanoma immune response, in particular innate antitumor immunity. Taken together, we discuss the evidence of pro-inflammatory and antitumor activities of Galectin-3 and suggest that Galectin-3 may be an important therapeutic target.