Enhanced drug resistance in cells coexpressing ErbB2 with EGF receptor or ErbB3

miRNAs as biomarkers of therapeutic response to HER2-targeted treatment in breast cancer: A systematic review

Breast cancer is the most common type of lethal cancer in women globally. Women have a 1 in 8 chance of developing breast cancer in their lifetime. Among the four primary molecular subtypes (luminal A, luminal B, HER2+, and triple-negative), HER2+ accounts for 20-25 % of all breast cancer and is rather aggressive. Although the treatment outcome of HER2+ breast cancer patients has been significantly improved with anti-HER2 agents, primary and acquired drug resistance present substantial clinical issues, limiting the benefits of HER2-targeted treatment. MicroRNAs (miRNAs) play a central role in regulating acquired drug resistance. miRNA are single-stranded, non-coding RNAs of around 20-25 nucleotides, known for essential roles in regulating gene expression at the post-transcriptional level. Increasing evidence has demonstrated that miRNA-mediated alteration of gene expression is associated with tumorigenesis, metastasis, and tumor response to treatment. Comprehensive knowledge of miRNAs as potential markers of drug response can help provide valuable guidance for treatment prognosis and personalized medicine for breast cancer patients.

Curcumin: A Novel Way to Improve Quality of Life for Colorectal Cancer Patients?

Colorectal cancer (CRC) is the third most common cancer in men and the second most common in women. Treatment of metastatic CRC consists of highly toxic chemotherapeutic drug combinations that often negatively affect patient quality of life (QoL). Moreover, chemotherapy-induced toxicity and chemotherapy resistance are among the most important factors limiting cancer treatment and can lead to the interruption or discontinuation of potentially effective therapy. Several preclinical studies have demonstrated that curcumin acts through multiple cellular pathways and possesses both anti-cancer properties against CRC and the capacity to mitigate chemotherapy-related side effects and overcome drug resistance. In this review article, we suggest that the addition of curcumin to the standard chemotherapeutic treatment for metastatic CRC could reduce associated side-effects and overcome chemotherapy resistance, thereby improving patient QoL.

Epiregulin increases stemness-associated genes expression and promotes chemoresistance of non-small cell lung cancer via ERK signaling

Background

Chemoresistance often causes the failure of treatment and death of patients with advanced non-small-cell lung cancer. However, there is still no resistance genes signature and available enriched signaling derived from a comprehensive RNA-Seq data analysis of lung cancer patients that could act as a therapeutic target to re-sensitize the acquired resistant cancer cells to chemo-drugs. Hence, in this study, we aimed to identify the resistance signature for clinical lung cancer patients and explore the regulatory mechanism.

Method

Analysis of RNA-Seq data from clinical lung cancer patients was conducted in R studio to identify the resistance signature. The resistance signature was validated by survival time of lung cancer patients and qPCR in chemo-resistant cells. Cytokine application, small-interfering RNA and pharmacological inhibition approaches were applied to characterize the function and molecular mechanism of EREG and downstream signaling in chemoresistance regulation via stemness.

Results

The RTK and vitamin D signaling were enriched among resistance genes, where 6 genes were validated as resistance signature and associated with poor survival in patients. EREG/ERK signaling was activated by chemo-drugs in NSCLC cells. EREG protein promoted the NSCLC resistance to chemo-drugs by increasing stemness genes expression. Additionally, inhibition of EREG/ErbB had downregulated ERK signaling, resulting in decreased expression of stemness-associated genes and subsequently re-sensitized the resistant NSCLC cells and spheres to chemo-drugs.

Conclusions

These findings revealed 6 resistance genes signature and proved that EREG/ErbB regulated the stemness to maintain chemoresistance of NSCLC via ERK signaling. Therefore, targeting EREG/ErbB might significantly and effectively resolve the chemoresistance issue.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02859-3.

A CGA/EGFR/GATA2 positive feedback circuit confers chemoresistance in gastric cancer

De novo and acquired resistance are major impediments to the efficacy of conventional and targeted cancer therapy. In unselected gastric cancer (GC) patients with advanced disease, trials combining chemotherapy and an anti-EGFR monoclonal antibody have been largely unsuccessful. In an effort to identify biomarkers of resistance so as to better select patients for such trials, we screened the secretome of chemotherapy-treated human GC cell lines. We found that levels of CGA, the α-subunit of glycoprotein hormones, were markedly increased in the conditioned media of chemoresistant GC cells, and CGA immunoreactivity was enhanced in GC tissues that progressed on chemotherapy. CGA levels in plasma increased in GC patients who received chemotherapy, and this increase was correlated with reduced responsiveness to chemotherapy and poor survival. Mechanistically, secreted CGA was found to bind to EGFR and activate EGFR signaling, thereby conferring a survival advantage to GC cells. N-glycosylation of CGA at Asn52 and Asn78 is required for its stability, secretion, and interaction with EGFR. GATA2 was found to activate CGA transcription, whose increase, in turn, induced the expression and phosphorylation of GATA2 in an EGFR-dependent manner, forming a positive feedback circuit that was initiated by GATA2 autoregulation upon sublethal exposure to chemotherapy. Based on this circuit, combination strategies involving anti-EGFR therapies or targeting CGA with microRNAs (miR-708-3p and miR-761) restored chemotherapy sensitivity. These findings identify a clinically actionable CGA/EGFR/GATA2 circuit and highlight CGA as a predictive biomarker and therapeutic target in chemoresistant GC.

Bortezomib induces methylation changes in neuroblastoma cells that appear to play a significant role in resistance development to this compound

The anticancer activity of bortezomib (BTZ) has been increasingly studied in a number of indications and promising results for the use of this treatment have been shown in neuroblastoma. As BTZ treatment is usually administered in cycles, the development of resistance and side effects in patients undergoing therapy with BTZ remains a major challenge for the clinical usage of this compound. Common resistance development also means that certain cells are able to survive BTZ treatment and bypass molecular mechanisms that render BTZ anticancer activity. We studied the methylome of neuroblastoma cells that survived BTZ treatment. Our results indicate that BTZ induces pronounced genome wide methylation changes in cells which recovered from the treatment. Functional analyses of identified methylation changes demonstrated they were involved in key cancer pathology pathways. These changes may allow the cells to bypass the primary anticancer activity of BTZ and develop a treatment resistant and proliferative phenotype. To study whether cells surviving BTZ treatment acquire a proliferative phenotype, we repeatedly treated cells which recovered from the first round of BTZ treatment. The repetitive treatment led to induction of the extraordinary proliferative potential of the cells, that increased with subsequent treatments. As we did not observe similar effects in cells that survived treatment with lenalidomide, and non-treated cells cultured under the same experimental conditions, this phenomenon seems to be BTZ specific. Overall, our results indicate that methylation changes may play major role in the development of BTZ resistance.

Curcumin: A therapeutic strategy for colorectal cancer?

Colorectal cancer (CRC) is the second cause of cancer death worldwide. The metastatic disease is mainly treated with aggressive therapies consisting on combinations of cytotoxic chemotherapy plus anti-EGFR or anti-VEGF drugs. In spite of the improvements in clinical outcomes achieved in the last decade, these are the result of multiple new combinations using the existing therapeutic options and the introduction of regorafenib and TAS-102 in second or later lines of treatment. As immunotherapies are limited to less than 5% of CRC patients harboring tumors with deficient mismatch repair, there is an urgent need of finding new drugs to increase our patients' survival opportunities. Among all the natural products that are candidates to be used for the treatment of CRC cancer, curcumin (the golden spice) is in the spotlight. Used for centuries in the Ayurveda medicine, its demonstrated anticancer properties and low toxicity profile made it the focus of hundreds of preclinical and clinical investigations. So far we know that it can be combined with most of the aforementioned drugs in a safe and synergistic way. Regretfully, its poor bioavailability has been one of the main issues for its successful introduction in the clinic. Nevertheless, a plethora of new formulations with a huge increase in bioavailability are under study with promising results. In this review we discuss the possibility of incorporating curcumin in the treatment of CRC; specifically, we review preclinical and clinical data supporting its possible combination with current therapies as well as new formulations under clinical study. It is time for the golden spice revolution.

Differential gene expression analysis of HNSCC tumors deciphered tobacco dependent and independent molecular signatures

Head and neck cancer is the sixth most common cancer worldwide, with tobacco as the leading cause. However, it is increasing in non-tobacco users also, hence limiting our understanding of its underlying molecular mechanisms. RNA-seq analysis of cancers has proven as effective tool in understanding disease etiology. In the present study, RNA-Seq of 86 matched Tumor/Normal pairs, of tobacco smoking (TOB) and non-smokers (N-TOB) HNSCC samples analyzed, followed by validation on 375 similar datasets. Total 2194 and 2073 differentially expressed genes were identified in TOB and N-TOB tumors, respectively. GO analysis found muscle contraction as the most enriched biological process in both TOB and N-TOB tumors. Pathway analysis identified muscle contraction and salivary secretion pathways enriched in both categories, whereas calcium signaling and neuroactive ligand-receptor pathway was more enriched in TOB and N-TOB tumors respectively. Network analysis identified muscle development related genes as hub node i. e. ACTN2, MYL2 and TTN in both TOB and N-TOB tumors, whereas EGFR and MYH6, depicts specific role in TOB and N-TOB tumors. Additionally, we found enriched gene networks possibly be regulated by tumor suppressor miRNAs such as hsa-miR-29/a/b/c, hsa-miR-26b-5p etc., suggestive to be key riboswitches in regulatory cascade of HNSCC. Interestingly, three genes PKLR, CST1 and C17orf77 found to show opposite regulation in each category, hence suggested to be key genes in separating TOB from N-TOB tumors. Our investigation identified key genes involved in important pathways implicated in tobacco dependent and independent carcinogenesis hence may help in designing precise HNSCC diagnostics and therapeutics strategies.

Stapled EGFR peptide reduces inflammatory breast cancer and inhibits additional HER-driven models of cancer

Background

The human epidermal growth factor receptor (HER) family of transmembrane tyrosine kinases is overexpressed and correlates with poor prognosis and decreased survival in many cancers. The receptor family has been therapeutically targeted, yet tyrosine kinase inhibitors (TKIs) do not inhibit kinase-independent functions and antibody-based targeting does not affect internalized receptors. We have previously demonstrated that a peptide mimicking the internal juxtamembrane domain of HER1 (EGFR; EJ1) promotes the formation of non-functional HER dimers that inhibit kinase-dependent and kinase-independent functions of HER1 (ERBB1/EGFR), HER2 (ERBB2) and HER3 (ERBB3). Despite inducing rapid HER-dependent cell death in vitro, EJ1 peptides are rapidly cleared in vivo, limiting their efficacy.

Method

To stabilize EJ1 activity, hydrocarbon staples (SAH) were added to the active peptide (SAH-EJ1), resulting in a 7.2-fold increase in efficacy and decreased in vivo clearance. Viability assays were performed across HER1 and HER2 expressing cell lines, therapeutic-resistant breast cancer cells, clinically relevant HER1-mutated lung cancer cells, and patient-derived glioblastoma cells, in all cases demonstrating improved efficacy over standard of care pan-HER therapeutics. Tumor burden studies were also performed in lung, glioblastoma, and inflammatory breast cancer mouse models, evaluating tumor growth and overall survival.

Results

When injected into mouse models of basal-like and inflammatory breast cancers, EGFRvIII-driven glioblastoma, and lung adenocarcinoma with Erlotinib resistance, tumor growth is inhibited and overall survival is extended. Studies evaluating the toxicity of SAH-EJ1 also demonstrate a broad therapeutic window.

Conclusions

Taken together, these data indicate that SAH-EJ1 may be an effective therapeutic for HER-driven cancers with the potential to eliminate triple negative inflammatory breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1939-7) contains supplementary material, which is available to authorized users.

Cationic block amphiphiles show anti-mitochondrial activity in multi-drug resistant breast cancer cells

Currently, there are limited treatment options for multi-drug resistant breast cancer. Lipid-modified cationic peptides have the potential to reach the mitochondria, which are attractive targets for the treatment of multi-drug resistant (MDR) breast cancer; yet, little is known about their mitochondrial targeting and anti-cancer activity. Interestingly, lipid-modified cationic peptides, typically used as gene transfection agents, exhibit similar structural features to mitochondrial targeted peptides. Using octahistidine-octaarginine (H₈R₈) as a model cationic peptide for cell penetration and endosomal escape, we explored the anti-cancer potential of lipid-modified cationic peptides as a function of amphiphilicity, biodegradability and lipid structure. We found that cationic peptides modified with a lipid that is at least 12 carbons in length exhibit potent anti-cancer activity in the low micromolar range in both EMT6/P and EMT6/AR-1 breast cancer cells. Comparing degradable and non-degradable linkers, as well as L- and D-amino acid sequences, we found that the anti-cancer activity is mostly independent of the biodegradation of the lipid-modified cationic peptides. Two candidates, stearyl-H₈R₈ (Str-H₈R₈) and vitamin E succinate-H₈R₈ (VES-H₈R₈) were cytotoxic to cancer cells by mitochondria depolarization. We observed increased reactive oxygen species (ROS) production, reduced cell bioenergetics and drug efflux, triggering apoptosis and G1 cell cycle arrest. Compared to Str-H₈R₈, VES-H₈R₈ showed enhanced cancer cell selectivity and drug efflux inhibition, thereby serving as a potential novel therapeutic agent. This study deepens our understanding of lipid-modified cationic peptides and uncovers their potential in multi-drug resistant breast cancer.

Functional genomic characterization of a synthetic anti-HER3 antibody reveals a role for ubiquitination by RNF41 in the anti-proliferative response

Dysregulation of the ErbB family of receptor tyrosine kinases is involved in the progression of many cancers. Antibodies targeting the dimerization domains of family members EGFR and HER2 are approved cancer therapeutics, but efficacy is restricted to a subset of tumors and resistance often develops in response to treatment. A third family member, HER3, heterodimerizes with both EGFR and HER2 and has also been implicated in cancer. Consequently, there is strong interest in developing antibodies that target HER3, but to date, no therapeutics have been approved. To aid the development of anti-HER3 antibodies as cancer therapeutics, we combined antibody engineering and functional genomics screens to identify putative mechanisms of resistance or synthetic lethality with antibody-mediated anti-proliferative effects. We developed a synthetic antibody called IgG 95, which binds to HER3 and promotes ubiquitination, internalization, and receptor down-regulation. Using an shRNA library targeting enzymes in the ubiquitin proteasome system, we screened for genes that effect response to IgG 95 and uncovered the E3 ubiquitin ligase RNF41 as a driver of IgG 95 anti-proliferative activity. RNF41 has been shown previously to regulate HER3 levels under normal conditions and we now show that it is also responsible for down-regulation of HER3 upon treatment with IgG 95. Moreover, our findings suggest that down-regulation of RNF41 itself may be a mechanism for acquired resistance to treatment with IgG 95 and perhaps other anti-HER3 antibodies. Our work deepens our understanding of HER3 signaling by uncovering the mechanistic basis for the anti-proliferative effects of potential anti-HER3 antibody therapeutics.

RANKL/RANK/OPG system beyond bone remodeling: involvement in breast cancer and clinical perspectives

RANKL/RANK/OPG system consists of three essential signaling molecules: i) the receptor activator of nuclear factor (NF)-kB-ligand (RANKL), ii) the receptor activator of NF-kB (RANK), and iii) the soluble decoy receptor osteoprotegerin (OPG). Although this system is critical for the regulation of osteoclast differentiation/activation and calcium release from the skeleton, different studies have elucidated its specific role in mammary gland physiology and hormone-driven epithelial proliferation during pregnancy. Of note, several data suggest that progesterone induces mammary RANKL expression in mice and humans. In turn, RANKL controls cell proliferation in breast epithelium under physiological conditions typically associated with higher serum progesterone levels, such as luteal phase of the menstrual cycle and pregnancy. Hence, RANKL/RANK system can be regarded as a major downstream mediator of progesterone-driven mammary epithelial cells proliferation, potentially contributing to breast cancer initiation and progression. Expression of RANKL, RANK, and OPG has been detected in breast cancer cell lines and in human primary breast cancers. To date, dysregulation of RANKL/RANK/OPG system at the skeletal level has been widely documented in the context of metastatic bone disease. In fact, RANKL inhibition through the RANKL-blocking human monoclonal antibody denosumab represents a well-established therapeutic option to prevent skeletal-related events in metastatic bone disease and adjuvant therapy-induced bone loss in breast cancer. On the other hand, the exact role of OPG in breast tumorigenesis is still unclear. This review focuses on molecular mechanisms linking RANKL/RANK/OPG system to mammary tumorigenesis, highlighting pre-clinical and clinical evidence for the potential efficacy of RANKL inhibition as a prevention strategy and adjuvant therapy in breast cancer settings.

Oligonucleotide aptamers against tyrosine kinase receptors: Prospect for anticancer applications

Transmembrane receptor tyrosine kinases (RTKs) play crucial roles in cancer cell proliferation, survival, migration and differentiation. Area of intense research is searching for effective anticancer therapies targeting these receptors and, to date, several monoclonal antibodies and small-molecule tyrosine kinase inhibitors have entered the clinic. However, some of these drugs show limited efficacy and give rise to acquired resistance. Emerging highly selective compounds for anticancer therapy are oligonucleotide aptamers that interact with their targets by recognizing a specific three-dimensional structure. Because of their nucleic acid nature, the rational design of advanced strategies to manipulate aptamers for both diagnostic and therapeutic applications is greatly simplified over antibodies. In this manuscript, we will provide a comprehensive overview of oligonucleotide aptamers as next generation strategies to efficiently target RTKs in human cancers.

Functional miRNAs in breast cancer drug resistance

Owing to improved early surveillance and advanced therapy strategies, the current death rate due to breast cancer has decreased; nevertheless, drug resistance and relapse remain obstacles on the path to successful systematic treatment. Multiple mechanisms responsible for drug resistance have been elucidated, and miRNAs seem to play a major part in almost every aspect of cancer progression, including tumorigenesis, metastasis, and drug resistance. In recent years, exosomes have emerged as novel modes of intercellular signaling vehicles, initiating cell–cell communication through their fusion with target cell membranes, delivering functional molecules including miRNAs and proteins. This review particularly focuses on enumerating functional miRNAs involved in breast cancer drug resistance as well as their targets and related mechanisms. Subsequently, we discuss the prospects and challenges of miRNA function in drug resistance and highlight valuable approaches for the investigation of the role of exosomal miRNAs in breast cancer progression and drug resistance.

Noncanonical SQSTM1/p62-Nrf2 pathway activation mediates proteasome inhibitor resistance in multiple myeloma cells via redox, metabolic and translational reprogramming

Multiple Myeloma (MM) is a B-cell malignancy characterized by the accumulation of clonal plasma cells in the bone marrow, with drug resistance being a major cause of therapeutic failure. We established a carfilzomib-resistant derivative of the LP-1 MM cell line (LP-1/Cfz) and found that the transcription factor NF-E2 p45-related factor 2 (Nrf2; gene symbol NFE2L2) contributes to carfilzomib resistance. The mechanism of Nrf2 activation involved enhanced translation of Nrf2 as well as its positive regulator, the autophagy receptor sequestosome 1 (SQSTM1)/p62. The eukaryotic translation initiation factor gene EIF4E3 was among the Nrf2 target genes upregulated in LP-1/Cfz cells, suggesting existence of a positive feedback loop. In line with this, we found that siRNA knockdown of eIF4E3 decreased Nrf2 protein levels. On the other hand, elevated SQSTM1/p62 levels were due at least in part to activation of the PERK-eIF2α pathway. LP-1/Cfz cells had decreased levels of reactive oxygen species as well as elevated levels of fatty acid oxidation and prosurvival autophagy. Genetic and pharmacologic inhibition of the Nrf2-EIF4E3 axis or the PERK-eIF2α pathway, disruption of redox homeostasis or inhibition of fatty acid oxidation or autophagy conferred sensitivity to carfilzomib. Our findings were supported by clinical data where increased EIF4E3 expression was predictive of Nrf2 target gene upregulation in a subgroup of patients with chemoresistant minimal residual disease and relapsed/refractory MM. Thus, our data offer a preclinical rationale for including inhibitors of the SQSTM1/p62-Nrf2 pathway to the treatment regimens for certain advanced stage MM patients.

Surrogate Predictive Biomarkers for Response to Anti-EGFR Agents: State of the Art and Challenges

The epidermal growth factor receptor (EGFR) plays a key role in cancer development and progression in several human malignancies including non-small cell lung cancer (NSCLC). Several strategies aimed at inhibiting the EGFR have been investigated in the last years, including the use of small tyrosine kinase inhibitors (TKIs) directed against the intracellular domain of the receptor and monoclonal antibodies targeting its extracellular portion. Subgroups of patients who are more likely to respond to TKIs have been identified based on both clincal and biological features. Never-smoking history has emerged as the most relevant clinical characteristic predictive of response to TKIs in NSCLC, while presence of drug-sensitive EGFR mutations and EGFR gene gain represent critical biological variables associated with an improved outcome for patients exposed to these agents. Recent studies have highlighted the existence of biological factors involved in intrinsic and acquired resistance to TKIs, including k-ras, HER-2 and EGFR exon 20 mutations. Increasing knowledge of EGFR biology and drug-receptor interactions will allow to identify individuals who are likely to derive a clinical benefit from the proposed targeted therapy, sparing refractory patients expensive and potentially toxic treatment.

Nucleolin and ErbB2 inhibition reduces tumorigenicity of ErbB2-positive breast cancer

ErbB2, a member of the ErbB family of receptor tyrosine kinases, is an essential player in the cell's growth and proliferation signaling pathways. Amplification or overexpression of ErbB2 is observed in ∼30% of breast cancer patients, and often drives cellular transformation and cancer development. Recently, we have shown that ErbB2 interacts with the nuclear-cytoplasmic shuttling protein nucleolin, an interaction which enhances cell transformation in vitro, and increases mortality risk and disease progression rate in human breast cancer patients. Given these results, and since acquired resistance to anti-ErbB2-targeted therapy is a major obstacle in treatment of breast cancer, we have examined the therapeutic potential of targeting the ErbB2-nucleolin complex. The effect of the nucleolin-specific inhibitor GroA (AS1411) on ErbB2-positive breast cancer was tested in vivo, in a mouse xenograft model for breast cancer; as well as in vitro, alone and in combination with the ErbB2 kinase-inhibitor tyrphostin AG-825. Here, we show that in vivo treatment of ErbB2-positive breast tumor xenografts with GroA reduces tumor size and leads to decreased ErbB2-mediated signaling. Moreover, we found that co-treatment of breast cancer cell lines with GroA and the ErbB2 kinase-inhibitor tyrphostin AG-825 enhances the anti-cancer effects exerted by GroA alone in terms of cell viability, mortality, migration, and invasiveness. We, therefore, suggest a novel therapeutic approach, consisting of combined inhibition of ErbB2 and nucleolin, which has the potential to improve breast cancer treatment efficacy.

The combination of curcumin and 5-fluorouracil in cancer therapy

5-Fluorouracil (5-FU) alone or in combination with other therapeutic drugs has been widely used for clinical treatment of various cancers. However, 5-FU-based chemotherapy has limited anticancer efficacy in clinic due to multidrug resistance and dose-limiting cytotoxicity. Some molecules and genes in cancer cells, such as nuclear factor kappa B, insulin-like growth factor-1 receptor, epidermal growth factor receptor, cyclooxygenase-2, signal transducer and activator of transcription 3, phosphatase and tensin homolog deleted on chromosome ten and Bcl-2 etc. are related to the chemoresistance and sensitivity of cancer cells to 5-FU. The activation of these molecules and genes expressions in cancer cells will be increased or decreased with long-term exposure of 5-FU. Curcumin has been found to be able to negatively regulate these processes. In order to overcome the problems of 5-FU, curcumin has been used to combine with 5-FU in cancer therapy.

Design, Synthesis, and Antitumor Activity of Novel Quinazoline Derivatives

In an attempt to explore a new class of epidermal growth factor receptor (EGFR) inhibitors, novel 4-stilbenylamino quinazoline derivatives were synthesized through a Dimorth rearrangement reaction and characterized via IR, ¹H-NMR, ¹³C-NMR, and HRMS. Methoxyl, methyl, halogen, and trifluoromethyl groups on stilbeneamino were detected. These synthesized compounds were evaluated for antitumor activity in vitro against eight human tumor cell lines with an MTS assay. Most synthesized compounds exhibited more potent activity (IC₅₀ = ~2.0 μM) than gefitinib (IC₅₀ > 10.0 μM) against the A431, A549, and BGC-823 cell lines. Docking methodology of compound 6c and 6i binding into the ATP site of EGFR was carried out. The results showed that fluorine and trifluoromethyl played an important role in efficient cell activity.

Sensitivity of docetaxel-resistant MCF-7 breast cancer cells to microtubule-destabilizing agents including vinca alkaloids and colchicine-site binding agents

Introduction

One of the main reasons for disease recurrence in the curative breast cancer treatment setting is the development of drug resistance. Microtubule targeted agents (MTAs) are among the most commonly used drugs for the treatment of breaset cancer and therefore overcoming taxane resistance is of primary clinical importance. Our group has previously demonstrated that the microtubule dynamics of docetaxel-resistant MCF-7_TXT cells are insensitivity to docetaxel due to the distinct expression profiles of β-tubulin isotypes in addition to the high expression of p-glycoprotein (ABCB1). In the present investigation we examined whether taxane-resistant breast cancer cells are more sensitive to microtubule destabilizing agents including vinca alkaloids and colchicine-site binding agents (CSBAs) than the non-resistant cells.

Methods

Two isogenic MCF-7 breast cancer cell lines were selected for resistance to docetaxel (MCF-7_TXT) and the wild type parental cell line (MCF-7_CC) to examine if taxane-resistant breast cancer cells are sensitive to microtubule-destabilizing agents including vinca alkaloids and CSBAs. Cytotoxicity assays, immunoblotting, indirect immunofluorescence and live imaging were used to study drug resistance, apoptosis, mitotic arrest, microtubule formation, and microtubule dynamics.

Results

MCF-7_TXT cells were demonstrated to be cross resistant to vinca alkaloids, but were more sensitive to treatment with colchicine compared to parental non-resistant MCF-7_CC cells. Cytotoxicity assays indicated that the IC₅₀ of MCF-7_TXT cell to vinorelbine and vinblastine was more than 6 and 3 times higher, respectively, than that of MCF-7_CC cells. By contrast, the IC₅₀ of MCF-7_TXT cell for colchincine was 4 times lower than that of MCF-7_CC cells. Indirect immunofluorescence showed that all MTAs induced the disorganization of microtubules and the chromatin morphology and interestingly each with a unique pattern. In terms of microtubule and chromain morphology, MCF-7_TXT cells were more resistant to vinorelbine and vinblastine, but more sensitive to colchicine compared to MCF-7_CC cells. PARP cleavage assay further demonstrated that all of the MTAs induced apoptosis of the MCF-7 cells. However, again, MCF-7_TXT cells were more resistant to vinorelbine and vinblastine, and more sensitive to colchicine compared to MCF-7_CC cells. Live imaging demonstrated that the microtubule dynamics of MCF-7_TXT cells were less sensitive to vinca alkaloids, and more sensitive to colchicine. MCF-7_TXT cells were also noted to be more sensitive to other CSBAs including 2MeOE₂, ABT-751 and phosphorylated combretastatin A-4 (CA-4P).

Conclusion

Docetaxel-resistant MCF-7_TXT cells have demonstrated cross-resistance to vinca alkaloids, but appear to be more sensitive to CSBAs (colchicine, 2MeOE₂, ABT-751 and CA-4P) compared to non-resistant MCF-7_CC cells. Taken together these results suggest that CSBAs should be evaluated further in the treatment of taxane resistant breast cancer.

RANK and EGFR in invasive breast carcinoma

Breast cancer is the most common malignancy, affecting one in eight women in North America and Europe. The human epidermal growth factor receptor (EGFR) protein comprises a major determinant of normal development but also cancer. RANK receptor (Receptor Activator of Nuclear factor-κB) is a tumor necrosis superfamily member and a binding partner for RANKL, which was recently implicated in breast cancer initiation, progression and metastasis. Here we provide preliminary evidence of a possible interplay between RANK and EGFR signaling in breast cancer. TCGA (cancergenome.nih.gov) publicly available data for EGFR and TNFRSF11A (RANK) genes from breast cancer patients and breast cancer cell lines were retrieved and analyzed. RANK mRNA showed a statistically significant positive correlation (p <0.001) with the mRNA and protein expression of EGFR, but not with ERBB2/3/4. Further analyses of survival data of a group of breast cancer patients (n = 248) from TCGA, revealed an EGFR^hi/RANK^hi subpopulation that showed a statistically significant (p = 0.001) reduced overall survival when compared to EGFR^low/RANK^low group of patients. Finally, EGFR and RANK combinatorial in vitro analyses revealed a significant upregulation of AKT and ERK signaling after EGF stimulation in cell lines and also an increase of breast cancer cell invasiveness.

Phenformin inhibits growth and epithelial-mesenchymal transition of ErbB2-overexpressing breast cancer cells through targeting the IGF1R pathway

Reports suggest that metformin, a popular anti-diabetes drug, prevents breast cancer through various systemic effects, including insulin-like growth factor receptor (IGFR) regulation. Although the anti-cancer properties of metformin have been well-studied, reports on a more bioavailable/potent biguanide, phenformin, remain sparse. Phenformin exerts similar functional activity to metformin and has been reported to impede mammary carcinogenesis in rats. Since the effects of phenformin on specific breast cancer subtypes have not been fully explored, we used ErbB2-overexpressing breast cancer cell and animal models to test the anti-cancer potential of phenformin. We report that phenformin (25-75 μM) decreased cell proliferation and impaired cell cycle progression in SKBR3 and 78617 breast cancer cells. Reduced tumor size after phenformin treatment (30 mg/kg/day) was demonstrated in an MMTV-ErbB2 transgenic mouse syngeneic tumor model. Phenformin also blocked epithelial-mesenchymal transition, decreased the invasive phenotype, and suppressed receptor tyrosine kinase signaling, including insulin receptor substrate 1 and IGF1R, in ErbB2-overexpressing breast cancer cells and mouse mammary tumor-derived tissues. Moreover, phenformin suppressed IGF1-stimulated proliferation, receptor tyrosine kinase signaling, and epithelial-mesenchymal transition markers in vitro. Together, our study implicates phenformin-mediated IGF1/IGF1R regulation as a potential anti-cancer mechanism and supports the development of phenformin and other biguanides as breast cancer therapeutics.

The potential of combi-molecules with DNA-damaging function as anticancer agents

DNA-damaging agents, such as methylating agents, chloroethylating agents and platinum-based agents, have been extensively used as anticancer drugs. However, the side effects, high toxicity, lack of selectivity and resistance severely limit their clinical applications. In recent years, a strategy combining a DNA-damaging agent with a bioactive molecule (e.g., enzyme inhibitors) or carrier (e.g., steroid hormone and DNA intercalators) to produce a new 'combi-molecule' with improved efficacy or selectivity has been attempted to overcome these drawbacks. The combi-molecule simultaneously acts on two targets and is expected to possess better potency than the parent compounds. Many studies have shown DNA-damaging combi-molecules exhibiting excellent anticancer activity in vitro and in vivo. This review focuses on the development of combi-molecules, which possess increased DNA-damaging potency, anticancer efficacy and tumor selectivity and reduced side reactions than the parent compounds. The future opportunities and challenges in the discovery of combi-molecules were also discussed.

Short-term early exposure to lapatinib confers lifelong protection from mammary tumor development in MMTV-erbB-2 transgenic mice

BACKGROUND

Although chemopreventative agents targeting the estrogen/estrogen receptor (ER) pathway have been effective for ER⁺ breast cancers, prevention of hormone receptor-negative breast cancers, such as Her2/erbB-2⁺ breast cancers, remains a significant issue. Previous studies have demonstrated that administration of EGFR/erbB-2-targeting lapatinib to MMTV-erbB-2 transgenic mice inhibited mammary tumor development. The prevention, however, was achieved by prolonged high dose exposure. The tolerance to high dose/long-term drug administration may hinder its potential in clinical settings. Therefore, we aimed to test a novel, short-term chemopreventative strategy using lapatinib during the premalignant risk window in MMTV-erbB-2 mice.

METHODS

We initially treated cultured cells with lapatinib to explore the anti-proliferative effects of lapatinib in vitro. We used a syngeneic tumor graft model to begin exploring the in vivo anti-tumorigenic effects of lapatinib in MMTV-erbB-2 mice. Then, we tested the efficacy of brief exposure to lapatinib (100 mg/kg/day for 8 weeks), beginning at 16 weeks of age, in the prevention of mammary tumor development in MMTV-erbB-2 mice.

RESULTS

In the syngeneic tumor transplant model, we determined that lapatinib significantly inhibited tumor cell proliferation. Furthermore, we demonstrated that short-term lapatinib exposure resulted in life-long protective effects, as supported by increased tumor latency in lapatinib-treated mice compared to the control mice. We further established that delayed tumor development in the treated mice was preceded by decreased BrdU nuclear incorporation and inhibited mammary morphogenesis. Molecular analysis indicated that lapatinib inhibited phosphorylation and expression of EGFR, erbB-3, erbB-2, Akt1, and Erk1/2 in premalignant mammary tissues. Also, lapatinib drastically inhibited the phosphorylation and expression of ERα and the transcription of ER target genes in premalignant mammary tissues. We also determined that lapatinib suppressed the stemness of breast cancer cell lines, as evidenced by decreased tumorsphere formation and ALDH⁺ cell populations.

CONCLUSIONS

Taken together, these data demonstrate that brief treatment with EGFR/erbB-2-targeting agents before the onset of tumors may provide lifelong protection from mammary tumors, through the concurrent inhibition of erbB-2 and ER signaling pathways and consequential reprogramming. Our findings support further clinical testing to explore the benefit of shorter lapatinib exposure in the prevention of erbB-2-mediated carcinogenesis.

Nucleolin-binding by ErbB2 enhances tumorigenicity of ErbB2-positive breast cancer

ErbB2 is an important member of the ErbB family, which activates growth and proliferation signaling pathways. ErbB2 is often overexpressed in various malignancies, especially in breast cancer, and is a common target for anti-cancer drugs. Breast cancer is currently one of the leading mortality causes in women, and acquired resistance to ErbB2-targeted therapies is a major obstacle in its treatment. Thus, understanding ErbB2-mediated signaling is crucial for further development of anti-cancer therapeutics and disease treatment. Previously, we have reported that the ErbB receptors interact with the major nucleolar protein nucleolin. In addition to its function in the nucleoli of cells, nucleolin participates in various cellular processes at the cytoplasm and cell-surface. Deregulated nucleolin is frequently overexpressed on the membrane of cancer cells. Here, we show that nucleolin increases colony formation and anchorage-independent growth of ErbB2-overexpressing cells. Importantly, this enhanced tumorigenicity also occurs in human ErbB2-positive breast cancer patients; namely, nucleolin overexpression in these patients is associated with reduced patient survival rates and increased disease-risk. ErbB2-nucleolin complexes are formed endogenously in both normal and cancer cells, and their effect on tumorigenicity is mediated through activation of ErbB2 signaling. Accordingly, nucleolin inhibition reduces cell viability and ErbB2 activation in ErbB2-positive cancer cells.

Synergistic Inhibitory Effects of Cetuximab and Cisplatin on Human Colon Cancer Cell Growth via Inhibition of the ERK-Dependent EGF Receptor Signaling Pathway

The purpose of this study was to evaluate the anticancer efficacy of cetuximab combined with cisplatin (combination treatment) on colon cancer growth, as well as its underlying action mechanism. Combination treatment synergistically potentiated the effect of cetuximab on cell growth inhibition and apoptosis induction in HCT116 and SW480 cells. Combination treatment further suppressed the expression of the activated form of epidermal growth factor receptor (EGFR) and MAP kinase (p-ERK and p-p38) and also significantly inhibited the activity of activator protein-1 (AP-1) and nuclear factor kappa B (NF-κB). Additionally, the expression of cyclooxygenase-2 (COX-2) and interleukin-8 (IL-8) mRNA was significantly reduced by the combination treatment as compared to the expression seen for treatment with cetuximab or cisplatin alone. We found that the synergistic inhibitory effects of cetuximab and cisplatin on AP-1 and NF-κB activation, as well as on cell viability, were reversed by pretreatment with an ERK inhibitor. Results demonstrate that combined treatment with cetuximab and cisplatin exerts synergistic anticancer effects on colon cancer cells and also suggest that the ERK pathway plays a critical role in these effects via the suppression of the EGFR signaling pathway, along with the inhibition of COX-2, IL-8, and AP-1 and NF-κB.

MicroRNA signatures in chemotherapy resistant esophageal cancer cell lines

AIM: To investigate expression of microRNA (miRNA) and potential targets in chemotherapy resistant esophageal cancer cell lines.

METHODS: An in-vitro model of acquired chemotherapy resistance in esophageal adeno- (EAC) and squamous cell carcinoma (ESCC) cells was used, and microRNA expression profiles for cisplatin or 5-fluorouracil (5-FU) resistant variants vs chemotherapy sensitive controls were compared using microarray and quantitative real-time polymerase chain reaction (PCR). The expression of chemotherapy-relevant genes potentially targeted by the dysregulated microRNAs in the chemotherapy resistant variants was also evaluated.

RESULTS: Chemotherapy resistant sublines were found to have specific miRNA signatures, and these miRNA signatures were different for the cisplatin vs 5-FU resistant cells from the same tumor cell line, and also for EAC vs ESCC cells with resistance to the same specific chemotherapy agent. Amongst others, miR-27b-3p, miR-193b-3p, miR-192-5p, miR-378 a-3p, miR-125a-5p and miR-18a-3p were dysregulated, consistent with negative posttranscriptional control of KRAS, TYMS, ABCC3, CBL-B and ERBB2 expression via these miRNAs.

CONCLUSION: The current study supports the hypothesis that microRNA expression has an impact on chemotherapy resistance in esophageal cancer.

Gene signatures of drug resistance predict patient survival in colorectal cancer

Different combinations of 5-fluorouracil (5-FU), oxaliplatin, irinotecan and other newly developed agents have been used to treat colorectal cancer. Despite the advent of new treatment regimens, the 5-year survival rate for metastatic colorectal cancer remains low (~10%). Knowing the drug sensitivity of a given tumor for a particular agent could significantly impact decision making and treatment planning. Biomarkers are proven to be successful in characterizing patients into different response groups. Using survival prediction analysis, we have identified three independent gene signatures, which are associated with sensitivity of colorectal cancer cells to 5-FU, oxaliplatin or irinotecan. On the basis of the three gene signatures, three score systems were developed to stratify patients from sensitive to resistance. These score systems exhibited robustness in stratify patients in two independent clinical studies. Patients with high scores in all three drugs exhibited the lowest survival.

Genetically encoded immunophotosensitizer 4D5scFv-miniSOG is a highly selective agent for targeted photokilling of tumor cells in vitro

Tumor-targeted delivery of cytotoxins presents considerable advantages over their passive transport. Chemical conjugation of cytotoxic module to antibody is limited due to insufficient reproducibility of synthesis, and recombinant immunotoxins are aimed to overcome this disadvantage. We obtained genetically encoded immunophotosensitizer 4D5scFv-miniSOG and evaluated its photocytotoxic effect in vitro. A single-chain variable fragment (scFv) of humanized 4D5 antibody was used as a targeting vehicle for selective recognition of the extracellular domain of human epidermal growth factor receptor 2 (HER2/neu) overexpressed in many human carcinomas. As a phototoxic module we used a recently described photoactivated fluorescent flavoprotein miniSOG. We found that recombinant protein 4D5scFv-miniSOG exerts a highly specific photo-induced cytotoxic effect on HER2/neu-positive human breast adenocarcinoma SK-BR-3 cells (IC₅₀= 160 nM). We demonstrated that the 4D5scFv-miniSOG specifically binds to HER2-positive cells and internalizes via receptor-mediated endocytosis. Co-treatment of breast cancer cells with 4D5scFv-miniSOG and Taxol or junction opener protein JO-1 produced remarkable additive effects.

Cetuximab inhibits oral squamous cell carcinoma invasion and metastasis via degradation of epidermal growth factor receptor

Cetuximab (Erbitux, C225) is a chimeric monoclonal antibody that binds to the extracellular domain of epidermal growth factor receptor (EGFR), inhibiting tumor growth, invasion, angiogenesis and metastasis. However, the mechanisms underlying the effect of Cetuximab in human oral squamous cell carcinoma (OSCC) remain unclear. Here, we report that Cetuximab modulates EGFR protein stability through the ubiquitin/proteasome pathway, resulting in the inhibition of human OSCC growth. Cetuximab significantly inhibited the migration and invasion of human OSCC cells by blocking epithelial/mesenchymal transition (EMT) and the AKT and ERK pathways. Furthermore, Cetuximab-inhibited cell growth by modulating the expression of integrin β5. Taken together, these results provide novel insights into the mechanism of Cetuximab action and suggest potential therapeutic strategies for OSCC.

Emerging targeted combinations in the management of breast cancer

The number of targeted treatments has risen exponentially over the last few years and is an important concept in the fight against cancer. This review will concentrate on some of the main treatments targeting aberrant pathways which have been tested mainly in the Phase I/II setting. These include human epidermal growth factor receptor 2 inhibitors, drug-antibody conjugates, epidermal growth factor receptor inhibitors, vascular endothelial growth factor inhibitors, reticular activating system, mammalian target of rapamycin and multi-kinase inhibitors. Further knowledge of these pathways and the predictors of response to them will enable personalized medicine to become a reality.

Increased expression of epidermal growth factor receptor (EGF-R) in patients with different forms of lung fibrosis

Introduction. Emerging evidence supports the role of epidermal growth factor-receptor (EGFR) in fibrogenesis. The aim of our study was to investigate the expression profiles of EGFR in three forms of IIPs, including idiopathic pulmonary fibrosis (IPF), cryptogenic organizing pneumonia (COP), and nonspecific interstitial pneumonia (NSIP). Patients and Methods. Twenty newly diagnosed patients with IPF, 15 with COP, and 15 with NSIP (cellular, n = 4 and fibrotic, n = 11) were investigated. Fifteen paraffin blocks obtained from the normal part of lungs removed for benign lesions were used as controls. Immunohistochemistry was carried out using specific monoclonal antibody. Results were verified by qRT-PCR. Results. A significant EGFR upregulation, both in protein and mRNA level, was observed in IPF, COP, and fibrotic NSIP samples compared to controls. EGFR was primarily localized in the hyperplastic alveolar epithelium surrounding areas of fibrosis in IPF, COP, and fibrotic NSIP samples, as assessed by double immunohistochemistry analysis with surfactant protein-A. EGFR mRNA levels were positively associated with indicators of lung fibrosis (type 1 collagen mRNA levels) and negatively correlated with functional prognostic parameters. Conclusions. We conclude that EGFR is upregulated in the hyperplastic alveolar epithelium in all three fibrotic forms of IIPs indicating a potential role during abnormal reepithelization.

Chronic morphine treatment attenuates cell growth of human BT474 breast cancer cells by rearrangement of the ErbB signalling network

Background

There is increasing evidence that opioid analgesics may interfere with tumour growth. It is currently thought that these effects are mediated by transactivation of receptor tyrosine kinase (RTK)-controlled ERK1/2 and Akt signalling. The growth of many breast cancer cells is dependent on hyperactive ErbB receptor networks and one of the most successful approaches in antineoplastic therapy during the last decade was the development of ErbB-targeted therapies. However, the response rates of single therapies are often poor and resistance mechanisms evolve rapidly. To date there is no information about the ability of opioid analgesics to interfere with the growth of ErbB-driven cancers.

Methods and Principal Findings

Here we demonstrate that ErbB2 overexpressing BT474 human breast cancer cells carry fully functional endogenous µ-opioid receptors. Most interestingly, the acute opioid effects on basal and Heregulin-stimulated ERK1/2 and Akt phosphorylation changed considerably during chronic Morphine treatment. Investigation of the underlying mechanism by the use of protein kinase inhibitors and co-immunoprecipitation studies revealed that chronic Morphine treatment results in rearrangement of the ErbB signalling network leading to dissociation of ERK1/2 from Akt signalling and a switch from ErbB1/ErbB3 to ErbB1/ErbB2-dependent cell growth. In chronically Morphine-treated cells Heregulin-stimulated ERK1/2 signalling is redirected via a newly established PI3K- and metalloproteinase-dependent feedback loop. Together, these alterations result in apoptosis of BT474 cells. A similar switch in Heregulin-stimulated ERK1/2 signalling from an ErbB2-independent to an ErbB2-, PI3K- and metalloproteinase-dependent mechanism was also observed in κ-opioid receptor expressing SKBR3 human mammary adenocarcinoma cells.

Conclusions and Significance

The present data demonstrate that the ErbB receptor network of human breast cancer cells represents a target for chronic Morphine treatment. Rearrangement of ErbB signalling by chronic Morphine may provide a promising strategy to enhance the sensitivity of breast cancer cells to ErbB-directed therapies and to prevent the development of escape mechanisms.

Combinatorial treatment of mammospheres with trastuzumab and salinomycin efficiently targets HER2-positive cancer cells and cancer stem cells

A major obstacle in the successful treatment of cancer is the occurrence of chemoresistance. Cancer cells surviving chemotherapy and giving rise to a recurrence of the tumor are termed cancer stem cells and can be identified by elevated levels of certain stem cell markers. Eradication of this cell population is a priority objective in cancer therapy. Here, we report elevated levels of stem cell markers in MCF-7 mammospheres. Likewise, an upregulation of HER2 and its differential expression within individual cells of mammospheres was observed. Sorting for HER2(high) and HER2(low) cells revealed an upregulation of stem cell markers NANOG, OCT4 and SOX2 in the HER2(low) cell fraction. Accordingly, HER2(low) cells also showed reduced proliferation, ductal-like outgrowths and an increased number of colonies in matrigel. Xenografts from subcutaneously injected HER2(low) sorted cells exihibited earlier onset but slower growth of tumors and an increase in stem cell markers compared to tumors developed from the HER2(high) fraction. Treatment of mammospheres with salinomycin reduced the expression of SOX2 indicating a selective targeting of cancer stem cells. Trastuzumab however, did not reduce the expression of SOX2 in mammospheres. Furthermore, a combinatorial treatment of mammospheres with trastuzumab and salinomycin was superior to single treatment with each drug. Thus, targeting HER2 expressing tumors with anti-HER2 therapies will not necessarily eliminate cancer stem cells and may lead to a more aggressive cancer cell phenotype. Our study demonstrates efficient killing of both HER2 positive cells and cancer stem cells, hence opening a possibility for a new combinatorial treatment strategy.

EGFR kinase promotes acquisition of stem cell-like properties: a potential therapeutic target in head and neck squamous cell carcinoma stem cells

Members of the EGFR/ErbB family of tyrosine kinases are found to be highly expressed and deregulated in many cancers, including head and neck squamous cell carcinoma (HNSCC). The ErbB family, including EGFR, has been demonstrated to play key roles in metastasis, tumorigenesis, cell proliferation, and drug resistance. Recently, these characteristics have been linked to a small subpopulation of cells classified as cancer stem cells (CSCs) which are believed to be responsible for tumor initiation and maintenance. In this study, we investigated the possible role of EGFR as a regulator of "stemness" in HNSCC cells. Activation of EGFR by the addition of EGF ligand or ectopic expression of EGFR in two established HNSCC cell lines (UMSCC-22B and HN-1) resulted in the induction of CD44, BMI-1, Oct-4, NANOG, CXCR4, and SDF-1. Activation of EGFR also resulted in increased tumorsphere formation, a characteristic ability of cancer stem cells. Conversely, treatment with the EGFR kinase inhibitor, Gefinitib (Iressa), resulted in decreased expression of the aforementioned genes, and loss of tumorsphere-forming ability. Similar trends were observed in a 99.9% CD44 positive stem cell culture derived from a fresh HNSCC tumor, confirming our findings for the cell lines. Additionally, we found that these putative cancer stem cells, when treated with Gefitinib, possessed a lower capacity to invade and became more sensitive to cisplatin-induced death in vitro. These results suggest that EGFR plays critical roles in the survival, maintenance, and function of cancer stem cells. Drugs that target EGFR, perhaps administered in combination with conventional chemotherapy, might be an effective treatment for HNSCC.

Modeling of miRNA and drug action in the EGFR signaling pathway

MicroRNAs have gained significant interest due to their widespread occurrence and diverse functions as regulatory molecules, which are essential for cell division, growth, development and apoptosis in eukaryotes. The epidermal growth factor receptor (EGFR) signaling pathway is one of the best investigated cellular signaling pathways regulating important cellular processes and its deregulation is associated with severe diseases, such as cancer. In this study, we introduce a systems biological model of the EGFR signaling pathway integrating validated miRNA-target information according to diverse studies, in order to demonstrate essential roles of miRNA within this pathway. The model consists of 1241 reactions and contains 241 miRNAs. We analyze the impact of 100 specific miRNA inhibitors (anit-miRNAs) on this pathway and propose that the embedded miRNA-network can help to identify new drug targets of the EGFR signaling pathway and thereby support the development of new therapeutic strategies against cancer.

The combination of gefitinib and RAD001 inhibits growth of HER2 overexpressing breast cancer cells and tumors irrespective of trastuzumab sensitivity

Background

HER2-positive breast cancers exhibit high rates of innate and acquired resistance to trastuzumab (TZ), a HER2-directed antibody used as a first line treatment for this disease. TZ resistance may in part be mediated by frequent co-expression of EGFR and by sustained activation of the mammalian target of rapamycin (mTOR) pathway. Here, we assessed feasibility of combining the EGFR inhibitor gefitinib and the mTOR inhibitor everolimus (RAD001) for treating HER2 overexpressing breast cancers with different sensitivity to TZ.

Methods

The gefitinib and RAD001 combination was broadly evaluated in TZ sensitive (SKBR3 and MCF7-HER2) and TZ resistant (JIMT-1) breast cancer models. The effects on cell growth were measured in cell based assays using the fixed molar ratio design and the median effect principle. In vivo studies were performed in Rag2M mice bearing established tumors. Analysis of cell cycle, changes in targeted signaling pathways and tumor characteristics were conducted to assess gefitinib and RAD001 interactions.

Results

The gefitinib and RAD001 combination inhibited cell growth in vitro in a synergistic fashion as defined by the Chou and Talalay median effect principle and increased tumor xenograft growth delay. The improvement in therapeutic efficacy by the combination was associated in vitro with cell line dependent increases in cytotoxicity and cytostasis while treatment in vivo promoted cytostasis. The most striking and consistent therapeutic effect of the combination was increased inhibition of the mTOR pathway (in vitro and in vivo) and EGFR signaling in vivo relative to the single drugs.

Conclusions

The gefitinib and RAD001 combination provides effective control over growth of HER2 overexpressing cells and tumors irrespective of the TZ sensitivity status.

Chemosensitization of tumors by resveratrol

Because tumors develop resistance to chemotherapeutic agents, the cancer research community continues to search for effective chemosensitizers. One promising possibility is to use dietary agents that sensitize tumors to the chemotherapeutics. In this review, we discuss that the use of resveratrol can sensitize tumor cells to chemotherapeutic agents. The tumors shown to be sensitized by resveratrol include lung carcinoma, acute myeloid leukemia, promyelocytic leukemia, multiple myeloma, prostate cancer, oral epidermoid carcinoma, and pancreatic cancer. The chemotherapeutic agents include vincristine, adriamycin, paclitaxel, doxorubicin, cisplatin, gefitinib, 5-fluorouracil, velcade, and gemcitabine. The chemosensitization of tumor cells by resveratrol appears to be mediated through its ability to modulate multiple cell-signaling molecules, including drug transporters, cell survival proteins, cell proliferative proteins, and members of the NF-κB and STAT3 signaling pathways. Interestingly, this nutraceutical has also been reported to suppress apoptosis induced by paclitaxel, vincristine, and daunorubicin in some tumor cells. The potential mechanisms underlying this dual effect are discussed. Overall, studies suggest that resveratrol can be used to sensitize tumors to standard cancer chemotherapeutics.

EGFR(s) in aging and carcinogenesis of the gastrointestinal tract

Cells of the gastrointestinal (GI) mucosa are subject to a constant process of renewal which, in normal adults, reflects a balance between the rates of cell production and cell loss. Detailed knowledge of these events is, therefore, essential for a better understanding of the normal aging processes as well as many GI diseases, particularly malignancy, that represent disorders of tissue growth. In general, many GI dysfunctions, including malignancy, increase with advancing age, and aging itself is associated with alterations in structural and functional integrity of the GI tract. Although the regulatory mechanisms for age-related increase in the incidence of GI-cancers are yet to be fully delineated, recent evidence suggests a role for epidermal growth family receptors and its family members {referred to as EGFR(s)} in the development and progression of carcinogenesis during aging. The present communication discusses the involvement of EGFR(s) in regulating events of GI cancers during advancing age and summarizes the current available therapeutics targeting these receptors. The current review also describes the effectiveness of ErbB inhibitors as well as combination therapies. Additionally, the involvement of GI stem cells in the development of the age-related rise in GI cancers is emphasized.

Polymorphism in epidermal growth factor receptor intron 1 predicts prognosis of patients with esophageal cancer after chemoradiation and surgery

BACKGROUND

The EGFR gene has been demonstrated to be an important factor influencing treatment response for various cancers, and its expression has been shown to be modified by the polymorphic CA repeat length at the 5'-regulatory sequence in intron 1. We investigated whether this EGFR polymorphism is associated with prognosis in patients with esophageal cancer after concurrent chemoradiotherapy (CCRT) and esophagectomy.

METHODS

A cohort of 148 patients with esophageal cancer received cisplatin-based CCRT (concurrently combined with 40 Gy irradiation) and subsequent esophagectomy. Their EGFR genotypes were determined by polymerase chain reaction from leukocyte DNA, which was obtained before treatment and was correlated with patient survival.

RESULTS

Patients with the homozygous short allele (<20 CA) of the EGFR gene in intron 1 were more likely to have a shorter duration of survival after CCRT and surgery than those with the homozygous long allele [adjusted hazard ratio (HR) (95% confidence interval [CI]) of death: 1.88 (1.02-3.49); P = 0.045]. This unfavorable prognostic effect of EGFR homozygous short CA repeat was mainly manifested in patients with good response to CCRT [adjusted HR (95% CI) of death 3.40 (1.06-10.89); P = 0.039]; it was less evident in those with poor response to CCRT [adjusted HR (95% CI) 1.40 (0.65-3.02); P = 0.384].

CONCLUSIONS

The EGFR CA repeat genetic polymorphism may act as a valuable molecular predictor of clinical outcome of esophageal cancer after CCRT and esophagectomy, especially in those with good response to CCRT.

Time-resolved fluorescence resonance energy transfer (TR-FRET) to analyze the disruption of EGFR/HER2 dimers: a new method to evaluate the efficiency of targeted therapy using monoclonal antibodies

In oncology, simultaneous inhibition of epidermal growth factor receptor (EGFR) and HER2 by monoclonal antibodies (mAbs) is an efficient therapeutic strategy but the underlying mechanisms are not fully understood. Here, we describe a time-resolved fluorescence resonance energy transfer (TR-FRET) method to quantify EGFR/HER2 heterodimers on cell surface to shed some light on the mechanism of such therapies. First, we tested this antibody-based TR-FRET assay in NIH/3T3 cell lines that express EGFR and/or HER2 and in various tumor cell lines. Then, we used the antibody-based TR-FRET assay to evaluate in vitro the effect of different targeted therapies on EGFR/HER2 heterodimers in the ovarian carcinoma cell line SKOV-3. A simultaneous incubation with Cetuximab (anti-EGFR) and Trastuzumab (anti-HER2) disturbed EGFR/HER2 heterodimers resulting in a 72% reduction. Cetuximab, Trastuzumab or Pertuzumab (anti-HER2) alone induced a 48, 44, or 24% reduction, respectively. In contrast, the tyrosine kinase inhibitors Erlotinib and Lapatinib had very little effect on EGFR/HER2 dimers concentration. In vivo, the combination of Cetuximab and Trastuzumab showed a better therapeutic effect (median survival and percentage of tumor-free mice) than the single mAbs. These results suggest a correlation between the extent of the mAb-induced EGFR/HER2 heterodimer reduction and the efficacy of such mAbs in targeted therapies. In conclusion, quantifying EGFR/HER2 heterodimers using our antibody-based TR-FRET assay may represent a useful method to predict the efficacy and explain the mechanisms of action of therapeutic mAbs, in addition to other commonly used techniques that focus on antibody-dependent cellular cytotoxicity, phosphorylation, and cell proliferation.

Time-resolved fluorescence resonance energy transfer (TR-FRET) to analyze the disruption of EGFR/HER2 dimers: a new method to evaluate the efficiency of targeted therapy using monoclonal antibodies

In oncology, simultaneous inhibition of epidermal growth factor receptor (EGFR) and HER2 by monoclonal antibodies (mAbs) is an efficient therapeutic strategy but the underlying mechanisms are not fully understood. Here, we describe a time-resolved fluorescence resonance energy transfer (TR-FRET) method to quantify EGFR/HER2 heterodimers on cell surface to shed some light on the mechanism of such therapies. First, we tested this antibody-based TR-FRET assay in NIH/3T3 cell lines that express EGFR and/or HER2 and in various tumor cell lines. Then, we used the antibody-based TR-FRET assay to evaluate in vitro the effect of different targeted therapies on EGFR/HER2 heterodimers in the ovarian carcinoma cell line SKOV-3. A simultaneous incubation with Cetuximab (anti-EGFR) and Trastuzumab (anti-HER2) disturbed EGFR/HER2 heterodimers resulting in a 72% reduction. Cetuximab, Trastuzumab or Pertuzumab (anti-HER2) alone induced a 48, 44, or 24% reduction, respectively. In contrast, the tyrosine kinase inhibitors Erlotinib and Lapatinib had very little effect on EGFR/HER2 dimers concentration. In vivo, the combination of Cetuximab and Trastuzumab showed a better therapeutic effect (median survival and percentage of tumor-free mice) than the single mAbs. These results suggest a correlation between the extent of the mAb-induced EGFR/HER2 heterodimer reduction and the efficacy of such mAbs in targeted therapies. In conclusion, quantifying EGFR/HER2 heterodimers using our antibody-based TR-FRET assay may represent a useful method to predict the efficacy and explain the mechanisms of action of therapeutic mAbs, in addition to other commonly used techniques that focus on antibody-dependent cellular cytotoxicity, phosphorylation, and cell proliferation.

Curcumin enhances dasatinib-induced inhibition of growth and transformation of colon cancer cells

Colorectal cancer is the third most common form of malignancy, behind prostate and lung cancers. Despite recent advances in medicine, mortality from colorectal cancer remains high, highlighting the need for improved therapies. Numerous studies have demonstrated increased activation of EGFR and its family members (EGFRs), IGF-1R as well as c-Src in colorectal cancer. The current study was undertaken to examine the effectiveness of combination therapy of dasatinib (BMS-354825; Bristol-Myers Squibb), a highly specific inhibitor of Src family kinases (SFK) and a nontoxic dietary agent; curcumin (diferuloylmethane), in colorectal cancer in in vitro and in vivo experimental models. For the latter, we utilized C57BL/6 APC(Min+/-) mice. Initial in vitro studies revealed synergistic interactions between the two agents. Additionally, we have observed that combination treatment causes a much greater inhibition of the following metastatic processes than either agent alone: (i) colony formation, (ii) invasion through extracellular matrix and (iii) tubule formation by endothelial cells. Dasatinib affects the cell adhesion phenotype of colon cancer HCT-116 cells whereas the combination therapy enhances this effect to a greater extent. Preclinical investigation revealed that the combination therapy to be highly effective causing an over 95% regression of intestinal adenomas in Apc(Min+/-) mice, which could be attributed to decreased proliferation and increased apoptosis. In conclusion, our data suggest that combination treatment of dasatinib and curcumin could be a potential therapeutic strategy for colorectal cancer.

Human TGFalpha-derived peptide TGFalphaL3 fused with superantigen for immunotherapy of EGFR-expressing tumours

Background

Monoclonal antibodies have been employed as targeting molecules of superantigen for the preclinical treatment of a variety of tumours. However, other targeting molecules, such as tumour-related ligands or peptides, are less exploited. Here, we tested other targeting molecules by genetically fusing the third loop of transforming growth factor alpha (TGFalphaL3) to mutant staphylococcal enterotoxin A (SEA_D227A).

Results

The resultant fusion proteins were expressed in E. coli and purified to homogeneity through a Ni-NTA affinity column. Fusion protein TGFalphaL3SEA_D227A can promote splenocyte proliferation to a level comparable to recombinant SEA (rSEA) and bind to EGFR-expressing tumour cells in an EGFR-dependent way. Consistent with these observations, TGFalphaL3SEA_D227A exerted an inhibitory effect on the growth of EGFR-expressing tumour cells both in vitro and in vivo. Notably, significant infiltrations of CD8⁺ and CD4⁺ T cells were detected in the tumour tissues of these C57BL/6 mice treated with TGFalphaL3SEA_D227A, suggesting the involvement of T cells in this tumour-inhibitory process.

Conclusions

The data here showed that TGFαL3 is capable of targeting superantigen to tumours and exerting an inhibitory effect on tumour growth, which enables TGFαL3SEA_D227A to be an attractive candidate for the immunotherapy of EGFR-expressing tumours.

S100A11, a dual growth regulator of epidermal keratinocytes

S100A11, a member of the family of S100 proteins, is a dimmer, each monomer of which has two EF-hands. Expression of S100A11 is ubiquitous in various tissues at different levels, with a high expression level in the skin. We have analyzed functions of S100A11 mainly in normal human keratinocytes (NHK) as a model cell system of human epithelial cells. High Ca(2+) and transforming growth factor-β (TGF-β), two representative growth suppressors for NHK, need a common S100A11-mediated pathway in addition to unique pathways (NFAT1-mediated pathway for high Ca(2+) and Smad-mediated pathway for TGF-β) for exhibiting a growth inhibitory effect. S100A11 has another action point for growth suppression in NHK. Annexin A1 (ANXA1) complexed with S100A11 efficiently binds to and inhibits cytosolic phospholipase A2 (cPLA2), the activity of which is needed for the growth of NHK. On exposure of NHK to epidermal growth factor (EGF), ANXA1 is cleaved at 12Trp, and this truncated ANXA1 loses binding capacity to S100A11, resulting in maintenance of an active state of cPLA2. On the other hand, we found that S100A11 is actively secreted by NHK. Extracellular S100A11 acts on NHK to enhance the production of EGF family proteins, resulting in growth stimulation. These findings indicate that S100A11 plays a dual role in growth regulation, being suppressive in cells and being promotive from outside of cells.

EGFR(S) inhibitors in the treatment of gastro-intestinal cancers: what's new?

In the past 10 to 15 years, a considerable progress has been made in the treatment of gastrointestinal (GI) related malignancies, as number of agents expanded from only one in 1995 to seven in 2006. Current review describes the recent role of targeted therapies, specifically EGFR inhibitors in the treatment of GI cancers. Importance of dietary agents in the treatment and prevention of GI cancers is also reviewed.