Epidermal growth factor regulates Mcl-1 expression through the MAPK-Elk-1 signalling pathway contributing to cell survival in breast cancer. Oncogene. 2011;30:2367-2378. [PMID: 21258408 PMCID: PMC3145838 DOI: 10.1038/onc.2010.616]

Antitumor activity of afatinib in EGFR T790M-negative human oral cancer therapeutically targets mTOR/Mcl-1 signaling axis

PURPOSE

This study investigates the role and effectiveness of the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) in oral cancer, focusing on the clinical relevance of EGFR and myeloid cell leukemia-1 (Mcl-1) in head and neck cancers (HNCs). It aims to explore the molecular mechanism of afatinib, a TKI, in treating human oral cancer.

METHODS

We conducted an in silico analysis using databases like The Cancer Genome Atlas, Gene Expression Omnibus, and Clinical Proteomic Tumor Analysis Consortium, along with immunohistochemistry staining, to study EGFR and Mcl-1 expression in HNCs. For investigating afatinib's anticancer properties, we performed various in vitro and in vivo analyses, including trypan blue exclusion assay, Western blotting, 4'-6-diamidino-2-phenylindole staining, flow cytometry, quantitative real-time PCR, Mitochondrial membrane potential assay, overexpression vector construction, transient transfection, and a tumor xenograft model.

RESULTS

Higher expression levels of EGFR and Mcl-1 were observed in HNC patient tissues compared to normal tissues, with their co-expression significantly linked to poor prognosis. There was a strong correlation between EGFR and Mcl-1 expressions in oral cancer patients. Afatinib treatment induced apoptosis and suppressed Mcl-1 in oral cancer cell lines without the EGFR T790M mutation. The mechanism of afatinib-induced apoptosis involved the EGFR/mTOR/Mcl-1 axis, as shown by the effects of mTOR activator MHY1485 and inhibitor rapamycin. Afatinib also increased Bim expression, mitochondrial membrane permeabilization, and cytochrome c release. It significantly lowered tumor volume without affecting body, liver, and kidney weights.

CONCLUSION

Afatinib, targeting the EGFR/mTOR/Mcl-1 axis, shows promise as a therapeutic strategy for oral cancer, especially in patients with high EGFR and Mcl-1 expressions.

Characterization of BCL-X L , MCL-1, and BAX Protein Expression in Response to Neoadjuvant Chemotherapy in Breast Cancer

The use of chemotherapy has improved the overall treatment of breast cancer, which is frequently administered in the form of neoadjuvant chemotherapy (NAC). Apoptosis is an established cell stress response to NAC in preclinical models; however, there is limited understanding of its role in clinical cancer, specifically, its contribution to favorable pathologic responses in breast cancer therapy. Here, we aimed to characterize the change in protein expression of 3 apoptosis-associated biomarkers, namely, BCL-X L , MCL-1, and BAX in breast cancer in response to NAC. For this, we utilized a set of 68 matched invasive breast cancer FFPE samples that were collected before (pre) and after (post) the exposure to NAC therapy that were characterized by incomplete pathologic response. Immunohistochemistry (IHC) analysis suggested that most of the samples show a decrease in the protein expression of all 3 markers following exposure to NAC as 90%, 69%, and 76% of the matched samples exhibited a decrease in expression for BCL-X L , MCL-1, and BAX, respectively. The median H-score of BCL-X L post-NAC was 150/300 compared with 225/300 pre-NAC ( P value <0.0001). The median H-score of MCL-1 declined from 200 pre-NAC to 160 post-NAC ( P value <0.0001). The median H-score of BAX protein expression decreased from 260 pre-NAC to 190 post-NAC ( P value <0.0001). There was no statistically significant association between the expression of these markers and stage, grade, and hormone receptor profiling (luminal status). Collectively, our data indicate that the expression of apoptosis regulatory proteins changes following exposure to NAC in breast cancer tissue, developing a partial pathologic response.

Role of the ubiquitin-proteasome system on macrophages in the tumor microenvironment

Tumor-associated macrophages (TAMs) are key components of the tumor microenvironment, and their different polarization states play multiple roles in tumors by secreting cytokines, chemokines, and so on, which are closely related to tumor development. In addition, the enrichment of TAMs is often associated with poor prognosis of tumors. Thus, targeting TAMs is a potential tumor treatment strategy, in which therapeutic approaches such as reducing TAMs numbers, remodeling TAMs phenotypes, and altering their functions are being extensively investigated. Meanwhile, the ubiquitin-proteasome system (UPS), an important mechanism of protein hydrolysis in eukaryotic cells, participates in cellular processes by regulating the activity and stability of key proteins. Interestingly, UPS plays a dual role in the process of tumor development, and its role in TAMs deserve to be investigated in depth. This review builds on this foundation to further explore the multiple roles of UPS on TAMs and identifies a promising approach to treat tumors by targeting TAMs with UPS.

Protease-activated receptor 2 attenuates doxorubicin-induced apoptosis in colon cancer cells

Drug resistance represents a major problem in cancer treatment. Doxorubicin (adriamycin) is an injectable DNA intercalating drug that halts cancer cell growth by inhibiting topoisomerase 2, but its long-term effectiveness is compromised by onset of resistance. This study demonstrates that expression of the PAR2 gene in human colon adenocarcinoma tissue samples was the highest among 32 different cancer types (n = 10,989), and higher in colon adenocarcinoma tissues (n = 331) than normal colon tissues (n = 308), revealing an association between PAR2 expression and human colon cancer. HT29 cells are a human colorectal adenocarcinoma cell line that is sensitive to the chemotherapeutic drug doxorubicin and also expresses PAR2. We find that PAR2 activation in HT29 cells, either by an endogenous protease agonist (trypsin) or an exogenous peptide agonist (2f-LIGRL-NH2), significantly reduces doxorubicin-induced cell death, reactive oxygen species production, caspase 3/7 activity and cleavage of caspase-8 and caspase-3. Moreover, PAR2-mediated MEK1/2-ERK1/2 pathway induced by 2f-LIGRL-NH2 leads to upregulated anti-apoptotic MCL-1 and Bcl-xL proteins that promote cellular survival. These findings suggest that activation of PAR2 compromises efficacy of doxorubicin in colon cancer. Further support for this conclusion came from experiments with human colon cancer HT29 cells, either with the PAR2 gene deleted or in the presence of a pharmacological antagonist of PAR2, which showed full restoration of all doxorubicin-mediated effects. Together, these findings reveal a strong link between PAR2 activation and signalling in human colon cancer cells and increased survival against doxorubicin-induced cell death. They support PAR2 antagonism as a possible new strategy for enhancing doxorubicin therapy.

YAP mediates resistance to EGF-induced apoptosis in EGFR-mutated non-small cell lung cancer cells

Mechanisms underlying the growth and survival of non-small cell lung cancer (NSCLC) cells positive for activating mutations of the epidermal growth factor receptor gene (EGFR) have remained unclear. We here examined the functional relation between such mutant forms of EGFR and Yes-associated protein (YAP), a transcriptional coactivator of the Hippo signaling pathway that regulates cell proliferation and survival. Under the condition of serum deprivation, epidermal growth factor (EGF) induced activation of YAP in NSCLC cell lines positive for mutated EGFR but not in those wild type (WT) for EGFR. Similar EGF-induced activation of YAP was apparent in A549 lung cancer cells forcibly expressing mutant EGFR but not in those overexpressing the WT receptor. Furthermore, EGF induced apoptotic cell death in serum-deprived A549 cells overexpressing the WT form of EGFR but not in those expressing mutant EGFR, and knockdown of YAP rendered the latter cells sensitive to this effect of EGF. Our results thus suggest that activation of YAP mediates resistance of EGFR-mutated NSCLC cells to EGF-induced apoptosis and thereby contributes specifically to the survival of such cells.

Dual-Targeted Therapy in HER2-Overexpressing Breast Cancer with Trastuzumab and Novel Cholesterol-Based Nioplexes Silencing Mcl-1

The challenge in HER2-overexpressing breast cancer therapy lies in creating an effective target therapy to overcome treatment resistance. Monoclonal antibodies and target gene silencing by siRNA are two potential strategies that have been widely developed for treating HER2-positive breast cancer. The siRNA delivery system is a crucial factor that influences siRNA therapy's success. In this study, lipid-based nanoparticles (cationic niosomes) composed of different cholesterol-based cationic lipids were formulated and characterized for delivering siRNA into HER2-overexpressing breast cancer cells. Niosomes containing a trimethylammonium headgroup showed the highest siRNA delivery efficiency with low toxicity. The myeloid cell leukemia-1 (Mcl-1) siRNA nioplex treatment significantly decreased mRNA expression and breast cancer cell growth. Dual-targeted therapy, consisting of treatment with an Mcl-1 siRNA nioplex and trastuzumab (TZ) solution, noticeably promoted cell-growth inhibition and apoptosis. The synergistic effect of dual therapy was also demonstrated by computer modeling software (CompuSyn version 1.0). These findings suggest that the developed cationic niosomes were effective nanocarriers for siRNA delivery in breast cancer cells. Furthermore, the Mcl-1 nioplex/TZ dual treatment establishes a synergistic outcome that may have the potential to treat HER2-overexpressing breast cancer.

The Tumorigenic Effect of the High Expression of Ladinin-1 in Lung Adenocarcinoma and Its Potential as a Therapeutic Target

The oncogenic role of Ladinin-1 (LAD1), an anchoring filament protein, is largely unknown. In this study, we conducted a series of studies on the oncogenic role of LAD1 in lung adenocarcinoma (LUAD). Firstly, we analyzed the aberrant expression of LAD1 in LUAD and its correlation with patient survival, tumor immune infiltration, and the activation of cancer signaling pathways. Furthermore, the relationship between LAD1 expression and K-Ras and EGF signaling activation, tumor cell proliferation, migration, and colony formation was studied by gene knockout/knockout methods. We found that LAD1 was frequently overexpressed in LUAD, and high LAD1 expression predicts a poor prognosis. LAD1 exhibits promoter hypomethylation in LUAD, which may contribute to its mRNA upregulation. Single-sample gene set enrichment analysis (ssGSEA) showed that acquired immunity was negatively correlated with LAD1 expression, which was verified by the downregulated GO terms of "Immunoglobulin receptor binding" and "Immunoglobulin complex circulating" in the LAD1 high-expression group through Gene Set Variation Analysis (GSVA). Notably, the Ras-dependent signature was the most activated signaling in the LAD1 high-expression group, and the phosphorylation of downstream effectors, such as ERK and c-jun, was strongly inhibited by LAD1 deficiency. Moreover, we demonstrated that LAD1 depletion significantly inhibited the proliferation, migration, and cell-cycle progression of LUAD cells and promoted sensitivity to Gefitinib, K-Ras inhibitor, and paclitaxel treatments. We also confirmed that LAD1 deficiency remarkably retarded tumor growth in the xenograft model. Conclusively, LAD1 is a critical prognostic biomarker for LUAD and has potential as an intervention target.

Mechanisms of EGFR-TKI-Induced Apoptosis and Strategies Targeting Apoptosis in EGFR-Mutated Non-Small Cell Lung Cancer

Homeostasis is achieved by balancing cell survival and death. In cancer cells, especially those carrying driver mutations, the processes and signals that promote apoptosis are inhibited, facilitating the survival and proliferation of these dysregulated cells. Apoptosis induction is an important mechanism underlying the therapeutic efficacy of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) for EGFR-mutated non-small cell lung cancer (NSCLC). However, the mechanisms by which EGFR-TKIs induce apoptosis have not been fully elucidated. A deeper understanding of the apoptotic pathways induced by EGFR-TKIs is essential for the developing novel strategies to overcome resistance to EGFR-TKIs or to enhance the initial efficacy through therapeutic synergistic combinations. Recently, therapeutic strategies targeting apoptosis have been developed for cancer. Here, we review the state of knowledge on EGFR-TKI-induced apoptotic pathways and discuss the therapeutic strategies for enhancing EGFR-TKI efficiency. We highlight the great progress achieved with third-generation EGFR-TKIs. In particular, combination therapies of EGFR-TKIs with anti-vascular endothelial growth factor/receptor inhibitors or chemotherapy have emerged as promising therapeutic strategies for patients with EGFR-mutated NSCLC. Nevertheless, further breakthroughs are needed to yield an appropriate standard care for patients with EGFR-mutated NSCLC, which requires gaining a deeper understanding of cancer cell dynamics in response to EGFR-TKIs.

Sensitization effect of kaempferol from persimmon leaves on HepG2 hepatoma cells with ABT-199 resistance and its molecular mechanisms

ABT-199 (venetoclax) is the first-in-class selective B-cell lymphoma 2 (BCL2) inhibitor, which is known to be ineffective towards liver cancer cells. Here, we investigated the efficacy and the underlying molecular processes of the sensitization effect of kaempferol isolated from persimmon leaves (KPL) on the ABT-199-resistant HepG2 cells. The effects of various doses of KPL coupled with ABT-199 on the proliferation of HepG2 cells and on the H22 liver tumor-bearing mouse model were examined, as well as the underlying mechanisms. Our findings showed that ABT-199 alone, in contrast to KPL, had no significant impact on hepatoma cell growth, both in vitro and in vivo. Interestingly, the combination therapy showed significantly higher anti-hepatoma efficacy. Mechanistic studies revealed that combining KPL and ABT-199 may promote both early and late apoptosis, as well as decrease the mitochondrial membrane potential in HepG2 cells. Western blot analysis showed that combination of KPL and ABT-199 significantly reduced the expression of the anti-apoptotic proteins Bcl-2, Bcl-xL, and Mcl-1, raised the expression of Bax and cleaved caspase 3, and enhanced cytochrome C release and Bax translocation. Therefore, KPL combined with ABT-199 has a potential application prospect in the treatment of hepatocellular carcinoma.

Understanding MCL1: from cellular function and regulation to pharmacological inhibition

Myeloid cell leukemia-1 (MCL1), an antiapoptotic member of the BCL2 family characterized by a short half-life, functions as a rapid sensor that regulates cell death and other relevant processes that include cell cycle progression and mitochondrial homeostasis. In cancer, MCL1 overexpression contributes to cell survival and resistance to diverse chemotherapeutic agents; for this reason, several MCL1 inhibitors are currently under preclinical and clinical development for cancer treatment. However, the nonapoptotic functions of MCL1 may influence their therapeutic potential. Overall, the complexity of MCL1 regulation and function represent challenges to the clinical application of MCL1 inhibitors. We now summarize the current knowledge regarding MCL1 structure, regulation, and function that could impact the clinical success of MCL1 inhibitors.

Transcriptional signatures of the BCL2 family for individualized acute myeloid leukaemia treatment

Background

Although anti-apoptotic proteins of the B-cell lymphoma-2 (BCL2) family have been utilized as therapeutic targets in acute myeloid leukaemia (AML), their complicated regulatory networks make individualized therapy difficult. This study aimed to discover the transcriptional signatures of BCL2 family genes that reflect regulatory dynamics, which can guide individualized therapeutic strategies.

Methods

From three AML RNA-seq cohorts (BeatAML, LeuceGene, and TCGA; n = 451, 437, and 179, respectively), we constructed the BCL2 family signatures (BFSigs) by applying an innovative gene-set selection method reflecting biological knowledge followed by non-negative matrix factorization (NMF). To demonstrate the significance of the BFSigs, we conducted modelling to predict response to BCL2 family inhibitors, clustering, and functional enrichment analysis. Cross-platform validity of BFSigs was also confirmed using NanoString technology in a separate cohort of 47 patients.

Results

We established BFSigs labeled as the BCL2, MCL1/BCL2, and BFL1/MCL1 signatures that identify key anti-apoptotic proteins. Unsupervised clustering based on BFSig information consistently classified AML patients into three robust subtypes across different AML cohorts, implying the existence of biological entities revealed by the BFSig approach. Interestingly, each subtype has distinct enrichment patterns of major cancer pathways, including MAPK and mTORC1, which propose subtype-specific combination treatment with apoptosis modulating drugs. The BFSig-based classifier also predicted response to venetoclax with remarkable performance (area under the ROC curve, AUROC = 0.874), which was well-validated in an independent cohort (AUROC = 0.950). Lastly, we successfully confirmed the validity of BFSigs using NanoString technology.

Conclusions

This study proposes BFSigs as a biomarker for the effective selection of apoptosis targeting treatments and cancer pathways to co-target in AML.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-022-01115-w.

Asprosin inhibits macrophage lipid accumulation and reduces atherosclerotic burden by up-regulating ABCA1 and ABCG1 expression via the p38/Elk-1 pathway

Background

Asprosin, a newly discovered adipokine, is a C-terminal cleavage product of profibrillin. Asprosin has been reported to participate in lipid metabolism and cardiovascular disease, but its role in atherogenesis remains elusive.

Methods

Asprosin was overexpressed in THP-1 macrophage-derived foam cells and apoE^−/− mice using the lentiviral vector. The expression of relevant molecules was determined by qRT-PCR and/or western blot. The intracellular lipid accumulation was evaluated by high-performance liquid chromatography and Oil red O staining. HE and Oil red O staining was employed to assess plaque burden in vivo. Reverse cholesterol transport (RCT) efficiency was measured using [³H]-labeled cholesterol.

Results

Exposure of THP-1 macrophages to oxidized low-density lipoprotein down-regulated asprosin expression. Lentivirus-mediated overexpression of asprosin promoted cholesterol efflux and inhibited lipid accumulation in THP-1 macrophage-derived foam cells. Mechanistic analysis revealed that asprosin overexpression activated p38 and stimulated the phosphorylation of ETS-like transcription factor (Elk-1) at Ser383, leading to Elk-1 nuclear translocation and the transcriptional activation of ATP binding cassette transporters A1 (ABCA1) and ABCG1. Injection of lentiviral vector expressing asprosin diminished atherosclerotic lesion area, increased plaque stability, improved plasma lipid profiles and facilitated RCT in apoE^−/− mice. Asprosin overexpression also increased the phosphorylation of p38 and Elk-1 as well as up-regulated the expression of ABCA1 and ABCG1 in the aortas.

Conclusion

Asprosin inhibits lipid accumulation in macrophages and decreases atherosclerotic burden in apoE^−/− mice by up-regulating ABCA1 and ABCG1 expression via activation of the p38/Elk-1 signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03542-0.

MCL-1 is a clinically targetable vulnerability in breast cancer

Pro-survival members of the BCL-2 family, including MCL-1, are emerging as important proteins during the development and therapeutic response of solid tumors. Notably, high levels of MCL-1 occur in breast cancer, where functional dependency has been demonstrated using cell lines and mouse models. The utility of restoring apoptosis in cancer cells through inhibition of pro-survival BCL-2 proteins has been realized in the clinic, where the first specific inhibitor of BCL-2 is approved for use in leukemia. A variety of MCL-1 inhibitors are now undergoing clinical trials for blood cancer treatment and application of this new class of drugs is also being tested in solid cancers. On-target compounds specific to MCL-1 have demonstrated promising efficacy in preclinical models of breast cancer and show potential to enhance the anti-tumor effect of conventional therapies. Taken together, this makes MCL-1 an extremely attractive target for clinical evaluation in the context of breast cancer.Abbreviations: ADC (antibody-drug conjugate); AML (Acute myeloid leukemia); APAF1 (apoptotic protease activating factor 1); bCAFs (breast cancer associated fibroblasts); BCL-2 (B-cell lymphoma 2); BH (BCL-2 homology); CLL (chronic lymphocytic leukemia); EGF (epidermal growth factor); EMT (epithelial to mesenchymal transition); ER (estrogen receptor); FDA (food and drug administration); GEMM (genetically engineered mouse model); HER2 (human epidermal growth factor 2); IL6 (interleukin 6); IMM (inner mitochondrial membrane); IMS (intermembrane space); MCL-1 (myeloid cell leukemia-1); MOMP (mitochondrial outer membrane permeabilisation); MM (multiple myeloma); PDX (patient-derived xenograft); OMM (outer mitochondrial membrane); PROTAC (proteolysis-targeting chimeras) TNBC (triple negative breast cancer); UPS (ubiquitin mediated proteolysis system).

Biallelic mutations in MOS cause female infertility characterized by human early embryonic arrest and fragmentation

Early embryonic arrest and fragmentation (EEAF) is a common phenomenon leading to female infertility, but the genetic determinants remain largely unknown. The Moloney sarcoma oncogene (MOS) encodes a serine/threonine kinase that activates the ERK signaling cascade during oocyte maturation in vertebrates. Here, we identified four rare variants of MOS in three infertile female individuals with EEAF that followed a recessive inheritance pattern. These MOS variants encoded proteins that resulted in decreased phosphorylated ERK1/2 level in cells and oocytes, and displayed attenuated rescuing effects on cortical F-actin assembly. Using oocyte-specific Erk1/2 knockout mice, we verified that MOS-ERK signal pathway inactivation in oocytes caused EEAF as human. The RNA sequencing data revealed that maternal mRNA clearance was disrupted in human mature oocytes either with MOS homozygous variant or with U0126 treatment, especially genes relative to mitochondrial function. Mitochondrial dysfunction was observed in oocytes with ERK1/2 deficiency or inactivation. In conclusion, this study not only uncovers biallelic MOS variants causes EEAF but also demonstrates that MOS-ERK signaling pathway drives human oocyte cytoplasmic maturation to prevent EEAF.

Targeting the BCL-2-regulated apoptotic pathway for the treatment of solid cancers

The deregulation of apoptosis is a key contributor to tumourigenesis as it can lead to the unwanted survival of rogue cells. Drugs known as the BH3-mimetics targeting the pro-survival members of the BCL-2 protein family to induce apoptosis in cancer cells have achieved clinical success for the treatment of haematological malignancies. However, despite our increasing knowledge of the pro-survival factors mediating the unwanted survival of solid tumour cells, and our growing BH3-mimetics armamentarium, the application of BH3-mimetic therapy in solid cancers has not reached its full potential. This is mainly attributed to the need to identify clinically safe, yet effective, combination strategies to target the multiple pro-survival proteins that typically mediate the survival of solid tumours. In this review, we discuss current and exciting new developments in the field that has the potential to unleash the full power of BH3-mimetic therapy to treat currently recalcitrant solid malignancies.

Characterizing therapeutic signatures of transcription factors in cancer by incorporating profiles in compound treated cells

MOTIVATION

Cancers are promoted by abnormal alterations in biological processes, such as cell cycle and apoptosis. An immediate reason for those aberrant processes is the deregulation of their involved transcription factors (TFs). Thus, the deregulated TFs in cancer have been experimented as successful therapeutic targets, such as RARA and RUNX1. This therapeutic strategy can be accelerated by characterizing new potential TF targets.

RESULTS

Two kinds of therapeutic signatures of TFs in A375 (skin) and HT29 (colon) cancer cells were characterized by analyzing TF activities under effective and ineffective compounds to cancer. First, the therapeutic TFs (TTs) were identified as the TFs that are significantly activated or repressed under effective compared to ineffective compounds. Second, the therapeutically correlated TF pairs (TCPs) were determined as the TF pairs whose activity correlations show substantial discrepancy between the effective and ineffective compounds. It was facilitated by incorporating (i)compound-induced gene expressions (LINCS), (ii) compound-induced cell viabilities (GDSC) and (iii) TF-target interactions (TRUST2). As a result, among 627 TFs, the 35 TTs (such as MYCN and TP53) and the 214 TCPs (such as FOXO3 and POU2F2 pair) were identified. The TTs and the proteins on the paths between TCPs were compared with the known therapeutic targets, tumor suppressors, oncogenes and CRISPR-Cas9 knockout screening, which yielded significant consequences. We expect that the results provide good candidates for therapeutic TF targets in cancer.

AVAILABILITY AND IMPLEMENTATION

The data and Python implementations are available at https://github.com/jmjung83/TT_and_TCP.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

CRISPR screens identify a novel combination treatment targeting BCL-XL and WNT signaling for KRAS/BRAF-mutated colorectal cancers

Metastatic or recurrent colorectal cancer (CRC) patients require systemic chemotherapy, but the therapeutic options of targeted agents remain limited. CRC patients with KRAS or BRAF gene mutations exhibit a worse prognosis and are resistant to anti-EGFR treatment. Previous studies have shown that the expression of anti-apoptotic protein BCL-X_L is increased in CRC patients with KRAS/BRAF mutations, suggesting BCL-X_L as a therapeutic target for this subgroup. Here, we performed genome-wide CRISPR/Cas9 screens of cell lines with KRAS mutations to investigate the factors required for sensitivity to BCL-X_L inhibitor ABT-263 using single-guide RNAs (sgRNAs) that induce loss-of-function mutations. In the presence of ABT-263, sgRNAs targeting negative regulators of WNT signaling (resulting in WNT activation) were enriched, whereas sgRNAs targeting positive regulators of WNT signaling (resulting in WNT inhibition) were depleted in ABT-263-resistant cells. The activation of WNT signaling was highly associated with an increased expression ratio of anti- to pro-apoptotic BCL-2 family genes in CRC samples. Genetic and pharmacologic inhibition of WNT signaling using β-catenin short hairpin RNA or TNIK inhibitor NCB-0846, respectively, augmented ABT-263-induced cell death in KRAS/BRAF-mutated cells. Inhibition of WNT signaling resulted in transcriptional repression of the anti-apoptotic BCL-2 family member, MCL1, via the functional inhibition of the β-catenin-containing complex at the MCL1 promoter. In addition, the combination of ABT-263 and NCB-0846 exhibited synergistic effects in in vivo patient-derived xenograft (PDX) models with KRAS mutations. Our data provide a novel targeted combination treatment strategy for the CRC patient subgroup with KRAS or BRAF mutations.

Curcuma amarissima Extract Activates Growth and Survival Signal Transduction Networks to Stimulate Proliferation of Human Keratinocyte

Simple Summary

Like many plants in the family of Zingiberaceae, Curcuma amarissima has been traditionally used to induce healing and tissue regeneration. However, there is no scientific evidence to explain how Curcuma amarissima works to accelerate wound healing. Our data clearly proved that Curcuma amarissima extract could potentially accelerate the closure of scratch wounds of human keratinocytes by stimulating cell proliferation. The potential mechanisms underlying these effects were defined to be associated with the activated signal transduction pathways relevant to cell proliferation and survival. This strongly suggests the ability of Curcuma amarissima to enhance the process of keratinocyte reepithelization during wound healing. Our current study provides convincing evidence that supports the possibility to develop an effective wound-healing promoting agent from this plant.

Abstract

Many medicinal plants have been used to treat wounds. Here, we revealed the potential wound healing effects of Curcuma amarissima (CA). Our cell viability assay showed that CA extract increased the viability of HaCaT cells that were cultured in the absence of serum. This increase in cell viability was proved to be associated with the pharmacological activities of CA extract in inducing cell proliferation. To further define possible molecular mechanisms of action, we performed Western blot analysis and immunofluorescence study, and our data demonstrated that CA extract rapidly induced ERK1/2 and Akt activation. Consistently, CA extract accelerated cell migration, resulting in rapid healing of wounded human keratinocyte monolayer. Specifically, the CA-induced increase of cell monolayer wound healing was blocked by the MEK inhibitor (U0126) or the PI3K inhibitor (LY294002). Moreover, CA extract induced the expression of Mcl-1, which is an anti-apoptotic protein, supporting that CA extract enhances human keratinocyte survival. Taken together, our study provided convincing evidence that Curcuma amarissima can promote proliferation and survival of human keratinocyte through stimulating the MAPK and PI3K/Akt signaling cascades. These promising data emphasize the possibility to develop this plant as a wound healing agent for the potential application in regenerative medicine.

Anticancer Activity of the Acetylenic Derivative of Betulin Phosphate Involves Induction of Necrotic-Like Death in Breast Cancer Cells In Vitro

Betulin (BT) is a natural pentacyclic lupane-type triterpene exhibiting anticancer activity. Betulin derivatives bearing propynoyloxy and phosphate groups were prepared in an effort to improve the availability and efficacy of the drug. In this study, a comparative assessment of the in vitro anticancer activity of betulin and its four derivatives was carried out using two human breast cancer cell lines: SK-BR-3 and MCF-7. In both studied cell lines, 30-diethoxyphosphoryl-28-propynoylbetulin (compound 4) turned out to be the most powerful inhibitor of growth and inducer of cellular death. Detailed examination of that derivative pertained to the mechanisms underlying its anticancer action. Treatment with compound 4 decreased DNA synthesis and up-regulated p21^WAF1/Cip1 mRNA and protein levels in both cell lines. On the other hand, that derivative caused a significant increase in cell death, as evidenced by increased lactate dehydrogenase (LDH) release and ethidium homodimer uptake. Shortly after the compound addition, an increased generation of reactive oxygen species and loss of mitochondrial membrane potential were detected. The activation of caspase-3 and fragmentation of genomic DNA suggested an apoptotic type of cell death. However, analysis of cellular morphology did not reveal any nuclear features typical of apoptosis. Despite necrosis-like morphology, dead cells exhibited activation of the cascade of caspases. These observations have led to the conclusion that compound 4 pushed cells to undergo a form of necrotic-like regulated cell demise.

Resistance of osteosarcoma cells to the proapoptotic effects of carfilzomib involves activation of mitogen activated protein kinase pathways

NEW FINDINGS

What is the central question of this study? Carfilzomib, a second-generation proteasome inhibitor approved for the treatment of multiple myeloma, shows efficacy against osteosarcoma. However, drug resistance remains a major challenge. What is the role of carfilzomib-induced changes in mitogen-activated protein kinase (MAPK) pathways in the sensitivity of osteosarcoma cells to the proapoptotic effects of the drug? What is the main finding and its importance? The dose-dependent antiapoptotic effects in osteosarcoma are associated with activation of MAPK signalling. Combinational targeting of MAPK signalling pathways can synergistically enhance carfilzomib-induced cell apoptosis, suggesting that MAPK inhibitors in combination with proteasome inhibitors can serve as a novel therapeutic tool for osteosarcoma.

ABSTRACT

Osteosarcoma is the most common primary bone malignancy. Despite efforts to improve outcomes, the overall survival rates for osteosarcoma have remained unchanged over the past three decades. In this study, we assessed the proapoptotic effects of the second-generation proteasome inhibitor carfilzomib on osteosarcoma and investigated the potential mechanisms underlying the synergistic proapoptotic action when combined with mitogen-activated protein kinase (MAPK) inhibitors. We found that carfilzomib alone significantly inhibited cell proliferation and induced apoptosis in a dose-dependent manner, characterized by the induction of cleaved caspase 3 and poly (ADP-ribose) polymerase. More importantly, focusing on the changes of antiapoptotic B-cell lymphoma 2 (Bcl-2) family members and signalling pathways, we found a striking induction of myeloid cell leukaemia 1 (Mcl-1) and the activation of MAPK pathways. Furthermore, we observed that combinational targeting of the MAPK pathways using the specific inhibitors U0126, SP600125 or SB203580 synergistically enhanced carfilzomib-induced cell apoptosis. Notably, we found that the combinational inhibition of extracellular signal-regulated kinase or c-Jun N-terminal kinase MAPK pathways significantly decreased the expression of the three antiapoptotic Bcl-2 family proteins, and in particular this reversed induction of Mcl-1 by carfilzomib. Collectively, our findings show that activation of the MAPK pathways contributes to the mechanisms of drug resistance to carfilzomib. In addition, the synergistic proapoptotic action of MAPK and proteasome inhibitors in osteosarcoma cells suggests that combinational therapy with both drug types may serve as a novel strategy for the clinical management of osteosarcoma.

Allele-Specific Role of ERBB2 in the Oncogenic Function of EGFR L861Q in EGFR-Mutant Lung Cancers

INTRODUCTION

Unlike common EGFR mutations, many less common EGFR mutations remain poorly characterized in terms of oncogenic function and drug sensitivity. Here, we characterize the subset of lung adenocarcinoma harboring EGFR L861Q through both preclinical and clinical investigations.

METHODS

We reviewed clinical and genomic data from patients with EGFR-mutant lung cancer. We established cells expressing EGFR mutations and performed functional analysis of L861Q in comparison with common EGFR mutations.

RESULTS

Among the patients with lung cancer, 3.4% (47 of 1367) possess an EGFR L861Q mutation. Of the patients with L861Q, 23.4% (11 of 47) had a concurrent exon 18 mutation (typically involving G719). In vitro studies revealed that the oncogenic activity of L861Q is dependent on asymmetric dimerization. Cells expressing L861Q were less sensitive to EGFR-specific inhibitors compared with cells expressing L858R but were similarly sensitive to pan-ERBB inhibitors. In cells expressing L861Q, ERBB2 phosphorylation was markedly higher compared with cells expressing L858R, and an enhanced interaction between EGFR and ERBB2 was observed in coimmunoprecipitation studies. In addition, treatment with osimertinib enhanced expression of the antiapoptotic protein MCL1, and knockdown of ERBB2 suppressed the expression of MCL1 in L861Q, raising the possibility of differential allele-specific cross-phosphorylation of ERBB2. Moreover, compared with EGFR-specific inhibitors, pan-ERBB inhibitors exerted superior growth inhibitory effects on cells expressing compound L861Q/G719X mutations.

CONCLUSIONS

Our results suggest that ERBB2 plays a previously unrecognized role in EGFR L861Q-driven tumorigenesis, and pan-ERBB inhibitors are likely to be more effective than selective EGFR tyrosine kinase inhibitors in this setting.

The FBW7-MCL-1 axis is key in M1 and M2 macrophage-related colon cancer cell progression: validating the immunotherapeutic value of targeting PI3Kγ

Colorectal cancer is a devastating disease with a low 5-year survival rate. Recently, many researchers have studied the mechanisms of tumor progression related to the tumor microenvironment. Here, we addressed the prognostic value of tumor-associated macrophages (TAMs) using a total of 232 CRC patient tissue samples and investigated the mechanisms underlying TAM-related colon cancer progression with respect to PI3Kγ regulation using in vitro, in vivo, and ex vivo approaches. Patients with M2/M1 < 3 had significantly improved progression-free survival and overall survival compared with patients with M2/M1 > 3. M1 and M2 macrophages elicited opposite effects on colon cancer progression via the FBW7-MCL-1 axis. Blocking macrophage PI3Kγ had cytotoxic effects on colon cancer cells and inhibited epithelial–mesenchymal transition features by regulating the FBW7-MCL-1 axis. The results of this study suggest that macrophage PI3Kγ may be a promising target for immunotherapy in colon cancer.

Drugs that target a specific subset of immune cells could render colorectal tumors more susceptible to immunological destruction by the host. The cellular composition of a tumor profoundly affects the odds of progression or survival, and some immune cell types can stall the antitumor response rather than strengthening it. Researchers led by Yong Beom Cho of Sungkyunkwan University, Seoul, South Korea, explored the impact of various subpopulations of macrophages, cells that help coordinate the immune counterattack against cancer. The researchers learned that the relative balance between M2 and M1 subtypes of macrophages correlates with colorectal cancer outcomes, patients with less M2 and more M1 activity generally faring better. They also uncovered a strategy for inhibiting M2 activity, which unleashes a more-aggressive response against the tumor and could thus offer a useful therapeutic approach.

Formononetin inhibits tumor growth by suppression of EGFR-Akt-Mcl-1 axis in non-small cell lung cancer

Background

Epidermal growth factor receptor (EGFR) activating mutations play crucial roles in the tumorigenesis of human non-small cell lung cancer (NSCLC). The mechanism regarding how EGFR signaling regulates myeloid cell leukemia sequence 1 (Mcl-1) protein stability and ubiquitination remains undefined.

Methods

MTS assay was used for natural product library screening. The effect of formononetin (Formo) on NSCLC cells was determined by MTS assay and soft agar assay. Molecular modeling was performed to analyze the potential different binding modes between Formo and EGFR WT or mutants. Mcl-1 protein level and the inhibitory effect of Formo on EGFR signaling were examined by immunoblot, in vitro kinase assay, in vitro pulldown and ATP competition assays, co-immunoprecipitation assay, ubiquitination analysis, in vivo xenograft model, and immunohistochemical staining.

Results

Formo was identified as an EGFR inhibitor by a 98 commercially available natural product screening. Formo suppresses WT and mutant EGFR kinases activity in vitro, ex vivo, and in vivo. Molecular modeling indicates that Formo docks into the ATP-binding pocket of both WT and mutant EGFR. Formo inhibits EGFR-Akt signaling, which in turn activates GSK3β and promotes Mcl-1 phosphorylation in NSCLC cells. Treatment with Formo enhances the interaction between Mcl-1 and SCF^Fbw7, which eventually promotes Mcl-1 ubiquitination and degradation. Depletion of either GSK3β or SCF^Fbw7 compromised Formo-induced Mcl-1 downregulation. Finally, Formo inhibits the in vivo tumor growth in a xenograft mouse model.

Conclusion

This study highlights the importance of promoting ubiquitination-dependent Mcl-1 turnover might be an alternative strategy to enhance the anti-tumor efficacy of EGFR-TKI.

PCNA-associated factor KIAA0101 transcriptionally induced by ELK1 controls cell proliferation and apoptosis in nasopharyngeal carcinoma: an integrated bioinformatics and experimental study

KIAA0101, previously identified as PCNA-associated factor, is overexpressed among almost majority of human cancers and has emerged as an important regulator of cancer progression; however, its function in human nasopharyngeal carcinoma (NPC) remain unknown. Integrated bioinformatics approaches were employed to determine the KIAA0101 expressions in the NPC samples. Lentiviral vectors carrying KIAA0101 shRNA were constructed and stable transfected cells were validated by qRT-PCR and western blot. Cellular functions were then evaluated by MTT, colony formation, Brdu staining, and flow cytometry. Mechanistic studies were systematically investigated by UCSC Genome Browser, GEO, UALCAN, QIAGEN, PROMO and JASPAR, ChIP, and the cBioPortal, et al. The results showed that KIAA0101 ranked top overexpressed gene lists in GSE6631 dataset. KIAA0101 was highly expressed in NPC tissues and cell lines. Furthermore, knockdown of KIAA0101 significantly inhibited cell proliferation and DNA replication, promoted apoptosis and cell cycle arrest in vitro. Meanwhile, the mechanistic study revealed that MAP kinase phosphorylation-dependent activation of ELK1 may enhance neighbor gene expressions of KIAA0101 and TRIP4 by binding both promotor regions in the NPC cells. Taken together, our findings indicate that overexpression of KIAA0101 activated by MAP kinase phosphorylation-dependent activation of ELK1 may play an important role in NPC progression.

Signal Transduction Pathways in Breast Cancer: The Important Role of PI3K/Akt/mTOR

Breast cancer is the cancer with the highest prevalence in women and is the number-one cause of cancer mortality worldwide. Cell transduction is a fundamental process in the development and progression of cancer. Modifications in various cell signalling pathways promote tumour cell proliferation, progression, and survival. The PI3K/Akt/mTOR pathway is an example of that, and it is involved in growth, proliferation, survival, motility, metabolism, and immune response regulation. Activation of this pathway is one of the main causes of cancer cell resistance to antitumour therapies. This makes PI3K/Akt/mTOR signalling a crucial object of study for understanding the development and progression of this disease. Thus, this pathway may have a role as a potential therapeutic target, as well as prognostic and diagnostic value, in patients with breast cancer. Despite the existence of selective PI3K/Akt/mTOR pathway inhibitors and current clinical trials, the cellular mechanisms are not yet known. The present review aims to understand the current state of this important disease and the paths that must be forged.

Deguelin suppresses non-small cell lung cancer by inhibiting EGFR signaling and promoting GSK3β/FBW7-mediated Mcl-1 destabilization

Activating mutations of epidermal growth factor receptor (EGFR) play crucial roles in the oncogenesis of human non-small cell lung cancer (NSCLC). By screening 79 commercially available natural products, we found that the natural compound deguelin exhibited a profound anti-tumor effect on NSCLC via directly down-regulating of EGFR-signaling pathway. Deguelin potently inhibited in vitro EGFR kinase activity of wild type (WT), exon 19 deletion, and L858R/T790M-mutated EGFR. The in silico docking study indicated that deguelin was docked into the ATP-binding pocket of EGFRs. By suppression of EGFR signaling, deguelin inhibited anchorage-dependent, and independent growth of NSCLC cell lines, and significantly delayed tumorigenesis in vivo. Further study showed that deguelin inhibited EGFR and downstream kinase Akt, which resulted in the activation of GSK3β and eventually enhanced Mcl-1 phosphorylation at S159. Moreover, deguelin promoted the interaction between Mcl-1 and E3 ligase SCF^FBW7, which enhanced FBW7-mediated Mcl-1 ubiquitination and degradation. Additionally, phosphorylation of Mcl-1 by GSK3β is a prerequisite for FBW7-mediated Mcl-1 destruction. Depletion or pharmacological inactivation of GSK3β compromised deguelin-induced Mcl-1 ubiquitination and reduction. Taken together, our data indicate that enhancement of ubiquitination-dependent Mcl-1 turnover might be a promising approach for cancer treatment.

Enabling Combinatorial siRNA Delivery against Apoptosis-Related Proteins with Linoleic Acid and α-Linoleic Acid Substituted Low Molecular Weight Polyethylenimines

PURPOSE

Short interfering RNA (siRNA) therapy promises a new era in treatment of breast cancers but effective delivery systems are needed for clinical use. Since silencing complementary targets may offer improved efficacy, this study was undertaken to identify non-viral carriers for combinatorial siRNA delivery for more effective therapy.

METHODS

A library of lipid-substituted polymers from low molecular weight polyethyleneimine (PEI), linoleic acid (LA) and α-linoleic acid (αLA) with amide or thioester linkages was prepared and investigated for delivering Mcl-1, survivin and STAT5A siRNAs in breast cancer cells.

RESULTS

The effective polymers formed 80-190 nm particles with similar zeta-potentials, but the serum stability was greater for complexes formed with amide-linked lipid conjugates. The LA and αLA substitutions, with the low molecular weight PEI (1.2 kDa and 2.0 kDa) were able to deliver siRNA effectively to cells and retarded the growth of breast cancer cells. The amide-linked lipid substituents showed higher cellular delivery of siRNA as compared to thioester linkages. Upon combinational delivery of siRNAs, growth of MCF-7 cells was inhibited to a greater extent with 2.0PEI-LA9 mediated delivery of Mcl-1 combined survivin siRNAs as compared to individual siRNAs. The qRT-PCR analysis confirmed the decrease in mRNA levels of target genes with specific siRNAs and 2.0PEI-LA9 was the most effective polymer for delivering siRNAs (either single or in combination).

CONCLUSIONS

This study yielded effective siRNA carriers for combinational delivery of siRNAs. Careful choice of siRNA combinations will be critical since targeting individual genes might alter the expression of other critical mediators.

MCL-1 antagonism enhances the anti-invasive effects of dasatinib in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest malignancies. It is phenotypically heterogeneous with a highly unstable genome and provides few common therapeutic targets. We found that MCL1, Cofilin1 (CFL1) and SRC mRNA were highly expressed by a wide range of these cancers, suggesting that a strategy of dual MCL-1 and SRC inhibition might be efficacious for many patients. Immunohistochemistry revealed that MCL-1 protein was present at high levels in 94.7% of patients in a cohort of PDACs from Australian Pancreatic Genome Initiative (APGI). High MCL1 and Cofilin1 mRNA expression was also strongly predictive of poor outcome in the TCGA dataset and in the APGI cohort. In culture, MCL-1 antagonism reduced the level of the cytoskeletal remodeling protein Cofilin1 and phosphorylated SRC on the active Y416 residue, suggestive of reduced invasive capacity. The MCL-1 antagonist S63845 synergized with the SRC kinase inhibitor dasatinib to reduce cell viability and invasiveness through 3D-organotypic matrices. In preclinical murine models, this combination reduced primary tumor growth and liver metastasis of pancreatic cancer xenografts. These data suggest that MCL-1 antagonism, while reducing cell viability, may have an additional benefit in increasing the antimetastatic efficacy of dasatinib for the treatment of PDAC.

Saga of Mcl-1: regulation from transcription to degradation

The members of the Bcl-2 family are the central regulators of various cell death modalities. Some of these proteins contribute to apoptosis, while others counteract this type of programmed cell death, thus balancing cell demise and survival. A disruption of this balance leads to the development of various diseases, including cancer. Therefore, understanding the mechanisms that underlie the regulation of proteins of the Bcl-2 family is of great importance for biomedical research. Among the members of the Bcl-2 family, antiapoptotic protein Mcl-1 is characterized by a short half-life, which renders this protein highly sensitive to changes in its synthesis or degradation. Hence, the regulation of Mcl-1 is of particular scientific interest, and the study of Mcl-1 modulators could aid in the understanding of the mechanisms of disease development and the ways of their treatment. Here, we summarize the present knowledge regarding the regulation of Mcl-1, from transcription to degradation, focusing on aspects that have not yet been described in detail.

Delivery of Cas13a/crRNA by self-degradable black phosphorus nanosheets to specifically inhibit Mcl-1 for breast cancer therapy

The constructed Cas13a/crRNA complex is delivered into cytoplasm by PBP via endocytosis, followed by endosomal escape based on biodegradation of the PBP, and efficiently knocked down Mcl-1 at transcriptional level for breast cancer therapy.

The heart of a hibernator: EGFR and MAPK signaling in cardiac muscle during the hibernation of thirteen-lined ground squirrels, Ictidomys tridecemlineatus

Background

Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) experience dramatic changes in physiological and molecular parameters during winter hibernation. Notably, these animals experience reduced blood circulation during torpor, which can put numerous stresses on their hearts. The present study evaluates the role played by the epidermal growth factor receptor (EGFR) in signal transduction during hibernation at low body temperature to evaluate signaling mechanisms. By investigating the regulation of intracellular mitogen activated protein kinase (MAPK) pathway responses, anti-apoptosis signals, downstream transcription factors, and heat shock proteins in cardiac muscle we aim to determine the correlation between upstream tyrosine phosphorylation events and downstream outcomes.

Methods

Protein abundance of phosphorylated EGFR, MAPKs and downstream effector proteins were quantified using immunoblotting and Luminex^® multiplex assays.

Results

Monitoring five time points over the torpor/arousal cycle, EGFR phosphorylation on T654, Y1068, Y1086 was found to increase significantly compared with euthermic control values particularly during the arousal process from torpor, whereas phosphorylation at Y1045 was reduced during torpor. Phosphorylation of intracellular MAPK targets (p-ERK 1/2, p-JNK, p-p38) also increased strongly during the early arousal stage with p-p38 levels also rising during prolonged torpor. However, of downstream MAPK effector kinases that were measured, only p-Elk-1 levels changed showing a decrease during interbout arousal (IA). Apoptosis markers revealed a strong reduction of the pro-apoptotic p-BAD protein during entrance into torpor that remained suppressed through torpor and IA. However, active caspase-9 protein rose strongly during IA. Levels of p-AKT were suppressed during the transition phases into and out of torpor. Of four heat shock proteins assessed, only HSP27 protein levels changed significantly (a 40% decrease) during torpor.

Conclusion

We show evidence of EGFR phosphorylation correlating to activation of MAPK signaling and downstream p-ELK1 suppression during hibernation. We also demonstrate a reduction in p-BAD mediated pro-apoptotic signaling during hibernation with active caspase-9 protein levels increasing only during IA. I. tridecemlineatus has natural mechanisms of tissue protection during hibernation that is largely due to cellular regulation through phosphorylation-mediated signaling cascade. We identify a possible link between EGFR and MAPK signaling via p-ERK, p-p38, and p-JNK in the cardiac muscle of these hibernating mammals that correlates with an apparent reduction in caspase-9 apoptotic signaling. This reveals a piece of the mechanism behind how these mammals are resilient to cardiac stresses during hibernation that would otherwise be damaging.

Kaempferia parviflora Extract Inhibits STAT3 Activation and Interleukin-6 Production in HeLa Cervical Cancer Cells

Kaempferia parviflora (KP) has been reported to have anti-cancer activities. We previously reported its effects against cervical cancer cells and continued to elucidate the effects of KP on inhibiting the production and secretion of interleukin (IL)-6, as well as its relevant signaling pathways involved in cervical tumorigenesis. We discovered that KP suppressed epidermal growth factor (EGF)-induced IL-6 secretion in HeLa cells, and it was associated with a reduced level of Glycoprotein 130 (GP130), phosphorylated signal transducers and activators of transcription 3 (STAT3), and Mcl-1. Our data clearly showed that KP has no effect on nuclear factor kappa B (NF-κB) localization status. However, we found that KP inhibited EGF-stimulated phosphorylation of tyrosine 1045 and tyrosine 1068 of EGF receptor (EGFR) without affecting its expression level. The inhibition of EGFR activation was verified by the observation that KP significantly suppressed a major downstream MAP kinase, ERK1/2. Consistently, KP reduced the expression of Ki-67 protein, which is a cellular marker for proliferation. Moreover, KP potently inhibited phosphorylation of STAT3, Akt, and the expression of Mcl-1 in response to exogenous IL-6 stimulation. These data suggest that KP suppresses EGF-induced production of IL-6 and inhibits its autocrine IL-6/STAT3 signaling critical for maintaining cancer cell progression. We believe that KP may be a potential alternative anti-cancer agent for suppressing cervical tumorigenesis.

3-Chloroplumbagin Induces Cell Death in Breast Cancer Cells Through MAPK-Mediated Mcl-1 Inhibition

Resistance acquired toward anti-cancer agents is a significant drawback in breast cancer therapy. A key factor contributing to drug resistance is apoptosis suppression associated with the upregulation of anti-apoptotic Bcl-2 family proteins. Specifically, the anti-apoptotic Mcl-1 protein has been shown to play a significant role in drug resistance, making it an important therapeutic target. The present study aimed at determining the antiproliferative activity of 3-chloroplumbagin (ChPL), a naphthoquinone derived from a Dionaea sp., toward breast cancer cells and examining the involvement of Mcl-1 inhibition in ChPL-induced cell death. The results showed that ChPL inhibited breast cancer cell proliferation and induced apoptosis through the intrinsic pathway through down-regulation of anti-apoptotic Bcl-2 family proteins. The induction of apoptosis by ChPL was found to be mediated through MAP kinase signaling inhibition. ChPL inhibited the phosphorylation of MEK and ERK proteins in breast cancer cells, and increased apoptosis induction in cells with reduced ERK expression. Furthermore, ERK silencing decreased the expression of Mcl-1 in ChPL-treated cells. The results of this research indicate that ChPL induces apoptosis in breast cancer cells through MAPK-mediated Mcl-1 inhibition, suggesting further research into its potential in breast cancer treatment.

Mechanosensitive ion channel Piezo1 promotes prostate cancer development through the activation of the Akt/mTOR pathway and acceleration of cell cycle

Prostate cancer is one of the most common types of cancer affecting men worldwide; however, its etiology and pathological mechanisms remain poorly understood. Mechanical stimulation plays a key role in prostate cancer development. Piezo type mechanosensitive ion channel component 1 (Piezo1), which functions as a cell sensor and transducer of mechanical stimuli, may have a crucial role in the development of prostate cancer. In the present study, the expression of the Piezo1 channel was demonstrated to be significantly elevated in prostate cancer cell lines and in human prostate malignant tumor tissues. Downregulation of Piezo1 significantly suppressed the viability, proliferation and migration of prostate cancer cells in vitro, and inhibited prostate tumor growth in vivo. The activation of the Akt/mTOR pathway or acceleration of cell cycle progression from G₀/G₁ to S phase may downstream consequences of Piezo 1 signal pathway activation. Downregulation of Piezo1 considerably suppressed Ca²⁺ signal increments, inhibited the phosphorylation of Akt and mTOR and arrested the cell cycle of prostate cancer cells at G₀/G₁ phase in while inhibiting the activation of CDK4 and cyclin D1. Taken together, these findings suggest that Piezo1 channels have a crucial role in prostate cancer development and may, therefore, be a novel therapeutic target in the treatment of prostate cancer.

EGFR mutations and AKT phosphorylation are markers for sensitivity to combined MCL-1 and BCL-2/xL inhibition in non-small cell lung cancer

Lung cancer is among the common and deadly cancers. Although the treatment options for late-stage cancer patients have continued to increase in numbers, the overall survival rates for these patients have not shown significant improvement. This highlights the need for new targets and drugs to more effectively treat lung cancer patients. In this study, we characterize the MCL-1 inhibitor maritoclax alone or in combination with a BCL-2/xL inhibitor in a panel of lung cancer cell lines. BCL-2 family proteins, phosphorylated proteins, and apoptosis were monitored following the treatments. We found that maritoclax was effective at inhibiting growth in these lung cancer cells. We also establish that cell lines with EGFR mutations were most sensitive to the combined inhibition of MCL-1 and BCL-2/xL. In addition, a high level of phosphorylated AKT (S473) was identified as a marker for sensitivity to the combination treatment. This work has defined EGFR mutations and AKT phosphorylation as markers for sensitivity to combined MCL-1 and BCL-2/xL targeted therapy and establishes a rationale to explore multiple BCL-2 family members in patients who are refractory to EGFR inhibitor treatment. Our data support the design of a clinical trial that aims to employ inhibitors of the BCL-2 family of proteins in lung cancer patients.

Specific protein 1, c-Abl and ERK1/2 form a regulatory loop

The tyrosine kinase c-Abl participates in the regulation of various cellular functions including cell proliferation, adhesion, migration, smooth muscle contraction and cancer progression. However, knowledge regarding transcriptional regulation of c-Abl is surprisingly limited. Sp1 is a founding member of the Sp1 transcription factor family that has been implicated in housekeeping gene expression, tumor cell proliferation and differentiation. Here, we show that knockdown and rescue of Sp1 affected growth factor-mediated c-Abl expression in cells. c-Abl promoter activity was also affected by Sp1 knockdown. This is the first evidence to suggest that Sp1 is an important transcription factor to regulate c-Abl expression. In addition, Sp1 phosphorylation at Thr-453 and Thr-739 has been proposed to regulate its activity in Drosophila cells. We unexpectedly found that growth factors did not induce Sp1 phosphorylation at these two residues. In contrast, growth factor stimulation upregulated Sp1 expression. Intriguingly, inhibition of ERK1 and ERK2 (ERK1/2, also known as MAPK3 and MAPK1, respectively) reduced expression of Sp1 and c-Abl. Furthermore, c-Abl knockdown diminished ERK1/2 phosphorylation and Sp1 expression. Taken together, these studies suggest that Sp1 can modulate c-Abl expression at transcription level. Conversely, c-Abl affects ERK1/2 activation and Sp1 expression in cells.

Rationally derived drug combinations with the novel Mcl-1 inhibitor EU-5346 in breast cancer

PURPOSE

Recent studies have emphasized a key role for the anti-apoptotic Bcl-2 family member Mcl-1 in conferring tumor cell survival and drug resistance in breast cancer (BC). Mcl-1 inhibitors, such as the BH3-mimetic EU-5346, therefore represent an exciting new class of targeting agents and are a current focus of widespread cancer-drug development efforts.

METHODS

ONCOMINE analysis was utilized to compare expression profiles of Bcl-2 family members across all major BC subgroups. Potential toxicities of EU-5346 were evaluated using iPS-generated cardiomyocytes, blood cells and astrocytes. The anti-BC cell activity of EU-5346-based therapies was evaluated using [³H]-thymidine uptake and spheroid-forming assays as well as immunoblotting and the Chou-Talalay method. Protein level-based activity of EU-5346, the specific anti-Bcl-2 inhibitor ABT-199 and the specific anti-Bcl-x_L inhibitor WEHI-539 was verified in Mcl-1^Δ/null versus Mcl-1^wt/wt MEFs.

RESULTS

We previously demonstrated significant anti-tumor activity of EU-5346 in all BC subtypes. Our present results go further and suggest that EU-5346 may induce limited adverse events such as cardiotoxicity, hematotoxicity, and neurotoxicity, frequently observed with other BH3 mimetics. As demonstrated by our mathematical scoring model, the prediction of EU-5643-induced IC₅₀ not only relies on the protein level of Mcl-1 but also on Bak, Bim, and Noxa. Synergistic anti-BC activity of low-dose EU-5346 with the BH3 mimetics ABT-199 or WEHI-539 was observed only in those BC cells expressing Bcl-2 or Bcl-x_L, respectively. Similarly, when combined with tamoxifen or trastuzumab, low-dose EU-5346 induced significant anti-BC activity in hormone receptor positive or Her2-positive BC cells, respectively. Finally, EU-5346 in combination with paclitaxel induced synergistic anti-BC activity in both paclitaxel-sensitive and paclitaxel-resistant TNBC cells.

CONCLUSION

These data strongly support the further clinical development of EU-5346 to improve BC patient survival.

Targeting Mcl-1 and other Bcl-2 family member proteins in cancer therapy

Regulation of both the extrinsic and the mitochondria-dependent intrinsic apoptotic pathways plays a key role in the development of the hematopoietic system, for sustaining cell survival during generation of various cell types, in eliminating cells with dual identities such as CD4/CD8 double-positive cells (Hettmann, Didonato, Karin, & Leiden, 1999; Ogasawara, Suda, & Nagata, 1995), for sustaining cells during the rapid clonal expansion phase (Schirmer, Vallejo, Weyand, & Gronzy, 1998), as well as eliminating cells during the contraction phase (Yajima et al., 2006). The anti-apoptotic protein Mcl-1 is necessary for sustaining hematopoietic stem cells (HPS) (Akashi et al., 2003; Akashi, Traver, Miyamoto, & Weissman, 2000). The anti-apoptotic factors Mcl-1, Bcl-2, and Bcl-xL were also found to be over-expressed in acute myeloid leukemia (AML) (Kaufmann et al., 2016) and acute lymphocytic leukemia (ALL) (Findley, Gu, Yeager, & Zhou, 1997), suggesting that dis-regulated apoptotic processes could be a factor in the instigation of leukemia and/or its relapse. Molecules targeting these proteins were used as single agents to treat leukemia. However, by using a set of recently developed specific molecule inhibitors targeting anti-apoptotic proteins, distinct roles are being discovered for these anti-apoptotic proteins during hematopoietic and tumor development. Furthermore, using these inhibitors in proper combinations can effectively induce apoptosis in various solid tumors, even though each agent on its own cannot induce apoptosis in them. These new findings suggest that inhibiting anti-apoptotic elements can induce apoptosis without external stimuli in most cells, but it comes with a risk that some combinations could also trigger apoptosis in healthy cells. One way to address the safety issue is by limiting exposure to all the agents to only cancer cells, thus making the combination safe and effective. In this article, we review this rapidly developing idea in cancer research.

Extracellular vesicles from triple-negative breast cancer cells promote proliferation and drug resistance in non-tumorigenic breast cells

Purpose

Triple-negative breast cancer (TNBC), an aggressive breast cancer subtype, is genetically heterogeneous which challenges the identification of clinically effective molecular makers. Extracellular vesicles (EVs) are key players in the intercellular signaling communication and have been shown to be involved in tumorigenesis. The main goal of this study was to evaluate the role and mechanisms of EVs derived from TNBC cells in modulating proliferation and cytotoxicity to chemotherapeutic agents in non-tumorigenic breast cells (MCF10A).

Methods

EVs were isolated from TNBC cell lines and characterized by nanoparticle tracking analysis, Western blot, and transmission electron microscopy. MCF10A cells were treated with the isolated EVs and evaluated for cell proliferation and cytotoxicity to Docetaxel and Doxorubicin by the MTT and MTS assays, respectively. Gene and miRNA expression profiling was performed in the treated cells to determine expression changes that may be caused by EVs treatment.

Results

MCF10A cells treated with HCC1806-EVs (MCF10A/HCC1806-EVs) showed a significant increase in cell proliferation and resistance to the therapeutic agents tested. No significant effects were observed in the MCF10A cells treated with EVs derived from MDA-MB-231 cells. Gene and miRNA expression profiling revealed 138 genes and 70 miRNAs significantly differentially expressed among the MCF10A/HCC1806-EVs and the untreated MCF10A cells, affecting mostly the PI3K/AKT, MAPK, and HIF1A pathways.

Conclusion

EVs isolated from the HCC1806 TNBC cells are capable of inducing proliferation and drug resistance on the non-tumorigenic MCF10A breast cells, potentially mediated by changes in genes and miRNAs expression associated with cell proliferation, apoptosis, invasion, and migration.

Electronic supplementary material

The online version of this article (10.1007/s10549-018-4925-5) contains supplementary material, which is available to authorized users.

High Myc expression and transcription activity underlies intra-tumoral heterogeneity in triple-negative breast cancer

We have previously identified a novel intra-tumoral dichotomy in triple-negative breast cancer (TNBC) based on the differential responsiveness to a reporter containing the Sox2 regulatory region-2 (SRR2), with reporter responsive (RR) cells being more stem-like than reporter unresponsive (RU) cells. Using bioinformatics, we profiled the protein-DNA binding motifs of SRR2 and identified Myc as one of the potential transcription factors driving SRR2 activity. In support of its role, Myc was found to be highly expressed in RR cells as compared to RU cells. Enforced expression of MYC in RU cells resulted in a significant increase in SRR2 activity, Myc-DNA binding, proportion of cellsexpressing CD44+/CD24-, chemoresistance and mammosphere formation. Knockdown of Myc using siRNA in RR cells led to the opposite effects. We also found evidence that the relatively high ERK activation in RR cells contributes to their high expression of Myc and stem-like features. Using confocal microscopy and patient samples, we found a co-localization between Myc and CD44 in the same cell population. Lastly, a high proportion of Myc-positive cells in tumors significantly correlated with a short patient survival. In conclusion, inhibition of the MAPK/ERK/Myc axis may be an effective approach in eliminating stem-like cells in TNBC.

NRAS-Mutated Rhabdomyosarcoma Cells Are Vulnerable to Mitochondrial Apoptosis Induced by Coinhibition of MEK and PI3K

Sequencing studies have revealed recurrent mutations in the RAS pathway in rhabdomyosarcoma (RMS). However, RAS effector pathways in RMS are poorly defined. Here, we report that coinhibition of NRAS or MEK plus PI3Kα triggers widespread apoptosis in NRAS-mutated RMS cells. Subtoxic concentrations of the MEK inhibitor MEK162 and the PI3Kα-specific inhibitor BYL719 synergized to trigger apoptosis in NRAS-mutated RMS cells in vitro and in vivoNRAS- or HRAS-mutated cell lines were more vulnerable to MEK162/BYL719 cotreatment than RAS wild-type cell lines, and MEK162/BYL719 cotreatment was more effective to trigger apoptosis in NRAS-mutated than RAS wild-type RMS tumors in vivo We identified BCL-2-modifying factor (BMF) as an inhibitory target of oncogenic NRAS, with either NRAS silencing or MEK inhibition upregulating BMF mRNA and protein levels, which BYL719 further increased. BMF silencing ablated MEK162/BYL719-induced apoptosis. Mechanistic investigations implicated a proapoptotic rebalancing of BCL-2 family members and suppression of cap-dependent translation in apoptotic sensitivity upon MEK162/BYL719 cotreatment. Our results offer a rationale for combining MEK- and PI3Kα-specific inhibitors in clinical treatment of RAS-mutated RMS.Significance: These findings offer a mechanistic rationale for combining MEK- and PI3Kα-specific inhibitors in the clinical treatment of RAS-mutated forms of often untreatable rhabdomyosarcomas. Cancer Res; 78(8); 2000-13. ©2018 AACR.

Control of cell death and mitochondrial fission by ERK1/2 MAP kinase signalling

The ERK1/2 signalling pathway is best known for its role in connecting activated growth factor receptors to changes in gene expression due to activated ERK1/2 entering the nucleus and phosphorylating transcription factors. However, active ERK1/2 also translocate to a variety of other organelles including the endoplasmic reticulum, endosomes, golgi and mitochondria to access specific substrates and influence cell physiology. In this article, we review two aspects of ERK1/2 signalling at the mitochondria that are involved in regulating cell fate decisions. First, we describe the prominent role of ERK1/2 in controlling the BCL2-regulated, cell-intrinsic apoptotic pathway. In most cases ERK1/2 signalling promotes cell survival by activating prosurvival BCL2 proteins (BCL2, BCL-xL and MCL1) and repressing prodeath proteins (BAD, BIM, BMF and PUMA). This prosurvival signalling is co-opted by oncogenes to confer cancer cell-specific survival advantages and we describe how this information has been used to develop new drug combinations. However, ERK1/2 can also drive the expression of the prodeath protein NOXA to control 'autophagy or apoptosis' decisions during nutrient starvation. We also describe recent studies demonstrating a link between ERK1/2 signalling, DRP1 and the mitochondrial fission machinery and how this may influence metabolic reprogramming during tumorigenesis and stem cell reprogramming. With advances in subcellular proteomics it is likely that new roles for ERK1/2, and new substrates, remain to be discovered at the mitochondria and other organelles.

miR-596 Modulates Melanoma Growth by Regulating Cell Survival and Death

Tumors grow because cancer cells lack the ability to balance cell survival and death signaling pathways. miR-596, a microRNA located at the 8p23.3 locus, has been shown by the TCGA-Assembler to be deleted in a significant number of melanoma samples. Here, we also validated the low levels of miR-596 in melanoma compared to tissue nevi, and Kaplan-Meier curve analysis revealed that low miR-596 expression was associated with worse overall survival. Moreover, we showed that miR-596 overexpression effectively inhibited MAPK/ERK signaling, cell proliferation, migration, and invasion and increased the cell apoptosis of melanoma cells. In addition, we found that miR-596 directly targets MEK1 and two apoptotic proteins, MCL1, and BCL2L1, in melanoma cells. Our findings indicated that miR-596 is an important miRNA that both negatively regulates the MAPK/ERK signaling pathway by targeting MEK1 and modulates the apoptosis pathway by targeting MCL1 and BCL2L1, suggesting that miR-596 could be a therapeutic candidate for treating melanoma, and a prognostic factor for melanoma patients.

Recent Advances in Comprehending the Signaling Pathways Involved in the Progression of Breast Cancer

This review describes recent advances in the comprehension of signaling pathways involved in breast cancer progression. Calcium sensing receptor (CaSR), caveolae signaling, signaling referred to hypoxia-inducing factors and disturbances in the apoptotic machinery are related to more general biological mechanisms and are considered first. The others refer to signaling pathways of more specific biological mechanisms, namely the heparin/heparin-sulfate interactome, over-expression of miRNA-378a-5p, restriction of luminal and basal epithelial cells, fatty-acid synthesis, molecular pathways related to epithelial to mesenchimal transition (EMT), HER-2/neu gene amplification and protein expression, and the expression of other members of the epithelial growth factor receptor family. This progress in basic research is fundamental to foster the ongoing efforts that use the new genotyping technologies, and aim at defining new prognostic and predictive biomarkers for a better personalized management of breast cancer disease.

Bioinformatics analysis of gene expression data for the identification of critical genes in breast invasive carcinoma

Gene expression data were analyzed in order to identify critical genes in breast invasive carcinoma (BRCA). Data from 1,073 BRCA samples and 99 normal samples were analyzed, which were obtained from The Cancer Genome Atlas. Differentially expressed genes (DEGs) were identified using the significance analysis of microarrays method and a functional enrichment analysis was performed using the Database for Annotation, Visualization and Integrated Discovery. Relevant microRNAs (miRNAs), transcription factors (TFs) and associated small molecule drugs were revealed by Fisher's exact test. Furthermore, protein-protein interaction (PPI) information was downloaded from the Human Protein Reference Database. Interactions with a Pearson's correlation coefficient >0.5 were identified and PPI networks were subsequently constructed. A survival analysis was also conducted according to the Kaplan-Meier method. Initially, the 1,073 BRCA samples were clustered into seven groups, and 5,394 DEGs that were identified in ≥4 groups were selected. These DEGs were involved in the cell cycle, ubiquitin-mediated proteolysis, oxidative phosphorylation and human immunodeficiency virus infection. In addition, TFs, including Sp1 transcription factor, DAN domain BMP antagonist family member 5, MYCN proto-oncogene, bHLH transcription factor and cAMP responsive element binding protein (CREB)1, were identified in the BRCA groups. Seven PPI networks were subsequently constructed and the top 10 hub genes were acquired, including RB transcriptional corepressor 1, inhibitor of nuclear factor (NF)-κB kinase subunit γ, NF-κB subunit 2, transporter 1, ATP binding cassette subfamily B member, CREB binding protein and proteasome subunit α3. A significant difference in survival was observed between the two combined groups (groups-2, −4 and −5 vs. groups-1, −3, −6 and −7). In conclusion, numerous critical genes were detected in BRCA, and relevant miRNAs, TFs and small molecule drugs were identified. These findings may advance understanding regarding the pathogenesis of BRCA.

ERK1/2 signalling protects against apoptosis following endoplasmic reticulum stress but cannot provide long-term protection against BAX/BAK-independent cell death

Disruption of protein folding in the endoplasmic reticulum (ER) causes ER stress. Activation of the unfolded protein response (UPR) acts to restore protein homeostasis or, if ER stress is severe or persistent, drive apoptosis, which is thought to proceed through the cell intrinsic, mitochondrial pathway. Indeed, cells that lack the key executioner proteins BAX and BAK are protected from ER stress-induced apoptosis. Here we show that chronic ER stress causes the progressive inhibition of the extracellular signal-regulated kinase (ERK1/2) signalling pathway. This is causally related to ER stress since reactivation of ERK1/2 can protect cells from ER stress-induced apoptosis whilst ERK1/2 pathway inhibition sensitises cells to ER stress. Furthermore, cancer cell lines harbouring constitutively active BRAFV600E are addicted to ERK1/2 signalling for protection against ER stress-induced cell death. ERK1/2 signalling normally represses the pro-death proteins BIM, BMF and PUMA and it has been proposed that ER stress induces BIM-dependent cell death. We found no evidence that ER stress increased the expression of these proteins; furthermore, BIM was not required for ER stress-induced death. Rather, ER stress caused the PERK-dependent inhibition of cap-dependent mRNA translation and the progressive loss of pro-survival proteins including BCL2, BCLXL and MCL1. Despite these observations, neither ERK1/2 activation nor loss of BAX/BAK could confer long-term clonogenic survival to cells exposed to ER stress. Thus, ER stress induces cell death by at least two biochemically and genetically distinct pathways: a classical BAX/BAK-dependent apoptotic response that can be inhibited by ERK1/2 signalling and an alternative ERK1/2- and BAX/BAK-independent cell death pathway.

Geraniin suppresses ovarian cancer growth through inhibition of NF-κB activation and downregulation of Mcl-1 expression

This study investigated the anticancer effects of geraniin on ovarian cancer cells and the signaling pathways involved. Ovarian cancer cells were treated with different concentrations of geraniin for 48 h and examined for viability, apoptosis, mitochondrial membrane depolarization, and gene expression. Xenograft tumor studies were performed to determine the anticancer activity of geraniin in vivo. Geraniin significantly decreased cancer cell viability in a concentration-dependent fashion. Geraniin significantly triggered apoptosis, which was accompanied by loss of mitochondrial membrane potential and increased cytochrome c release and caspsase-3 activity. Mechanistically, geraniin significantly downregulated Mcl-1 and impaired NF-κB p65 binding to the mcl-1 promoter. Overexpression of Mcl-1 significantly reversed geraniin-induced apoptosis in OVCAR3 cells. In addition, geraniin retarded ovarian cancer growth and reduced expression of phospho-p65 and Mcl-1. Collectively, geraniin elicits growth suppression in ovarian cancer through inhibition of NF-κB and Mcl-1 and may provide therapeutic benefits for this malignancy.