Targeting the MAPK-RAS-RAF signaling pathway in cancer therapy

Targeted Therapy: Attacking Cancer with Molecular and Immunological Targeted Agents

Today, personalized cancer therapy with targeted agents has taken center stage, and offers individualized treatment to many. As the mysteries of the genes in a cell's DNA and their specific proteins are defined, advances in the understanding of cancer gene mutations and how cancer evades the immune system have been made. This article provides a basic and simplified understanding of the available (Food and Drug Administration- approved) molecularly and immunologically targeted agents in the USA. Other agents may be available in Asia, and throughout the USA and the world, many more agents are being studied. Nursing implications for drug classes are reviewed.

Annurca Apple Nutraceutical Formulation Enhances Keratin Expression in a Human Model of Skin and Promotes Hair Growth and Tropism in a Randomized Clinical Trial

Several pharmaceutical products have been formulated over the past decades for the treatment of male and female alopecia, and pattern baldness, but relatively few metadata on their efficacy have been published. For these reasons, the pharmaceutical and medical attention has recently focused on the discovery of new and safer remedies. Particularly, great interest has been attracted by oligomeric procyanidin bioactivity, able to promote hair epithelial cell growth as well as to induce the anagen phase. Specifically, the procyanidin B2, a dimeric derivative extracted from apples, has demonstrated to be one of the most effective and safest natural compounds in promoting hair growth, both in vitro and in humans by topical applications. By evaluating the polyphenolic content of different apple varieties, we have recently found in the apple fruits of cv Annurca (AFA), native to Southern Italy, one of the highest contents of oligomeric procyanidins, and, specifically, of procyanidin B2. Thus, in the present work we explored the in vitro bioactivity of AFA polyphenolic extract as a nutraceutical formulation, named AppleMets (AMS), highlighting its effects on the cellular keratin expression in a human experimental model of adult skin. Successively, testing the effects of AMS on hair growth and tropism in healthy subjects, we observed significant results in terms of increased hair growth, density, and keratin content, already after 2 months. This study proves for the first time the impact of apple procyanidin B2 on keratin biosynthesis in vitro, and highlights its effect as a nutraceutical on human hair growth and tropism.

Extracting Fitness Relationships and Oncogenic Patterns among Driver Genes in Cancer

Driver mutation provides fitness advantage to cancer cells, the accumulation of which increases the fitness of cancer cells and accelerates cancer progression. This work seeks to extract patterns accumulated by driver genes (“fitness relationships”) in tumorigenesis. We introduce a network-based method for extracting the fitness relationships of driver genes by modeling the network properties of the “fitness” of cancer cells. Colon adenocarcinoma (COAD) and skin cutaneous malignant melanoma (SKCM) are employed as case studies. Consistent results derived from different background networks suggest the reliability of the identified fitness relationships. Additionally co-occurrence analysis and pathway analysis reveal the functional significance of the fitness relationships with signaling transduction. In addition, a subset of driver genes called the “fitness core” is recognized for each case. Further analyses indicate the functional importance of the fitness core in carcinogenesis, and provide potential therapeutic opportunities in medicinal intervention. Fitness relationships characterize the functional continuity among driver genes in carcinogenesis, and suggest new insights in understanding the oncogenic mechanisms of cancers, as well as providing guiding information for medicinal intervention.

Detection of EGFR and BRAF mutations by competitive allele-specific TaqMan polymerase chain reaction in lung adenocarcinoma

Epithelial growth factor receptor (EGFR)-tyrosine kinase inhibitors are the standard first-line treatment for patients with metastatic non-small cell lung cancer (NSCLC) expressing sensitive EGFR-mutants. Other drugs target different driver mutants, including the serine/threonine-protein kinase B-raf (BRAF) inhibitor dabrafenib, which has exhibited promising efficacy for treating patients with metastatic BRAF-mutated NSCLC. Therefore, identifying patients carrying mutations that may be treated using targeted therapies is important. However, the methods of molecular detection presently applied in clinical practice, particularly detection of BRAF in NSCLC patients, require further investigation. Therefore, more sensitive and economic methods are required. The present study applied the competitive allele-specific TaqMan polymerase chain reaction (CastPCR) technology to the molecular detection of EGFR (del2235-2249, del2236-2250, T790M, L858R) and BRAF (V600E, G469A, D594G) mutations in 144 treatment-naive patients with lung adenocarcinoma, and analyzed the association between the mutation rates and patients' clinicopathological features. 51.4% (74/144) cases were identified harboring EGFR mutations. A total of 40.3% (58/144) patients carried sensitizing mutations (exon 19 deletion or L858R) and 14.6% (21/144) carried T790M mutations. 6.9% (10/144) mutation-positive patients were double-mutated. Total EGFR mutation rate was significantly increased in female compared with that of males (60.9 vs. 43.8%, P<0.05), in non-smokers compared with that of smokers (62.8 vs. 34.5%, P<0.05). In total, 8.3% (12/144) patients were identified with BRAF mutations. 16.7% were V600E (2/12) and 83.3% (10/12) were non-V600E mutants. Among the 10 non-V600E mutations, D594G accounted for 90.0% (9/10) and G469A accounted for 10.0% (1/10). Statistical analysis demonstrated that the BRAF mutation rate was not associated with any of the following clinicopathological features: Sex, age, smoking history, clinical stages, distant metastasis, differentiation degree, tumor size and regional lymph node metastasis (P≥0.05). CastPCR technology is a robust method with high sensitivity for the molecular detection of EGFR and BRAF mutations in clinical formalin-fixed paraffin-embedded samples.

Oncogenic pathways as the basis of primary immune ignorance

The success of immune checkpoint inhibitor therapies (ICTs) to bring about durable clinical responses in a subset of patients with different cancer histologies is transforming cancer care. However, many patients do not benefit from single-agent ICT, including patients with melanoma and non-small cell lung cancer, which are often considered to be immunogenic tumor types. In addition, several other common solid tumors, such as breast, colon, and prostate cancers, have reported very low response rates. A growing body of evidence suggests that the majority of tumors may be categorized as being primary immune-ignorant tumors, hence precluding response to single-agent ICTs. The molecular mechanisms that govern the immune-ignorant phenotype are under intense investigation. This review focuses on how oncogenic pathways can promote the development of a primary immune-ignorant tumor.

Integrator orchestrates RAS/ERK1/2 signaling transcriptional programs

In this study, Yue et al. describe a new role for the RNAPII-associated complex Integrator in MAPK signaling. They show that Integrator mediates the transcriptional responsiveness following growth factor signaling, that depletion of Integrator can suppress MAPK signaling to the nucleus, and that Integrator could be targeted in MAPK-driven cancers that are resistant to conventional inhibitors of the MAPK pathway.

Activating mutations in the mitogen-activated protein kinase (MAPK) cascade, also known as the RAS–MEK–extracellular signal-related kinase (ERK1/2) pathway, are an underlying cause of >70% of human cancers. While great strides have been made toward elucidating the cytoplasmic components of MAPK signaling, the key downstream coactivators that coordinate the transcriptional response have not been fully illustrated. Here, we demonstrate that the MAPK transcriptional response in human cells is funneled through Integrator, an RNA polymerase II-associated complex. Integrator depletion diminishes ERK1/2 transcriptional responsiveness and cellular growth in human cancers harboring activating mutations in MAPK signaling. Pharmacological inhibition of the MAPK pathway abrogates the stimulus-dependent recruitment of Integrator at immediate early genes and their enhancers. Following epidermal growth factor (EGF) stimulation, activated ERK1/2 is recruited to immediate early genes and phosphorylates INTS11, the catalytic subunit of Integrator. Importantly, in contrast to the broad effects of Integrator knockdown on MAPK responsiveness, depletion of a number of critical subunits of the coactivator complex Mediator alters only a few MAPK-responsive genes. Finally, human cancers with activating mutations in the MAPK cascade, rendered resistant to targeted therapies, display diminished growth following depletion of Integrator. We propose Integrator as a crucial transcriptional coactivator in MAPK signaling, which could serve as a downstream therapeutic target for cancer treatment.

Identification of a New Potent Inhibitor Targeting KRAS in Non-small Cell Lung Cancer Cells

KRAS (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) is an oncogenic driver with mutations in 30% of non-small cell lung cancer (NSCLC). However, there is no effective clinical drug even though it has been identified as an oncogene for 30 years. In this study, we identified a small molecule inhibitor compound 0375-0604 targeting KRAS by using molecular docking based virtual screening approach. Compound 0375-0604 had a good binding affinity to KRAS in vitro and exhibited cytotoxicity in oncogenic KRAS expressing NSCLC cell lines. Further mechanism study showed that compound 0375-0604 can block the formation of the complex of guanosine triphosphate (GTP) and KRAS in vitro. In addition, compound 0375-0604 inhibited KRAS downstream signaling pathway RAF/MEK/ERK and RAF/PI3K/AKT. Finally, we also found that this compound can inhibit the cell growth through G2/M cell cycle arrest and induce apoptosis on the NSCLC cell lines harboring KRAS mutation. Therefore, compound 0375-0604 may be considered as a potential KRAS inhibitor for treatment of NSCLC carrying KRAS oncogene.

A miR-20a/MAPK1/c-Myc regulatory feedback loop regulates breast carcinogenesis and chemoresistance

Chemoresistance often leads to the failure of breast cancer treatment. MicroRNAs (miRNAs) play an important role in the progression and chemoresistance of cancer. However, because of the complexity of the mechanisms of chemoresistance and the specificity of miRNA regulation in different cell types, the function of miR-20a in breast cancer chemoresistance is still unclear. Here, by using miRNA microarray and high-content screening techniques, we found that miR-20a/b were significantly downregulated in breast cancer tissues compared with normal breast tissues, and low miR-20a/b expression was correlated with poor survival in breast cancer patients. Ectopic overexpression of miR-20a sensitized breast cancer cells to a broad spectrum of chemotherapy drugs and suppress their proliferation both in vitro and in vivo. Further study demonstrated that miR-20a directly targeted the 3'untranslated region of MAPK1, and thus downregulated the expression of P-gp and c-Myc by inhibiting the MAPK/ERK signaling pathway, whereas c-Myc can bind to the promoter region of the miR-20a gene to promote the expression of miR-20a. Together, our study identified a novel miR-20a/MAPK1/c-Myc feedback loop that regulates breast cancer growth and chemoresistance. These findings suggest that miR-20a synergizing with anticancer drugs will be a promising treatment strategy, especially for chemoresistant patients.

Inhibition of HSP90 sensitizes a novel Raf/ERK dual inhibitor CY-9d in triple-negative breast cancer cells

Raf and extracellular signal-regulated kinases (ERK) are both important therapeutic targets in the mitogen-activated protein kinase (MAPK) pathway, and play crucial roles in the apoptosis resistance of breast cancer cells. In the present study, cytotoxic and apoptosis-inducing activities of the Raf/ERK dual inhibitor CY-9d were found to be restricted in triple negative breast cancer (TNBC) cells compared with ER/PR-positive cells. Based on the analysis of differentially expressed proteins using a quantitative proteomic iTRAQ method and bioinformatics analysis, HSP90 was found to identify as a potential mediator between Raf and ERK in TNBC cells. Western blotting and RNA interference suggested that down-regulated IQGAP1 can attenuate the routine Raf/MEK/ERK cascade and recruit HSP90 as a bypass pathway. Simultaneous treatment with the HSP90 inhibitor and CY-9d at sub-therapeutic doses was found to produce synergistic therapeutic and apoptosis-inducing effects in TNBC cells. Moreover, CY-9d was also found to suppress breast cancer growth, inhibit the activation of Raf/ERK, and induce mitochondrial apoptosis in vivo without remarkable toxicity. These results support the combination of HSP90 and Raf/ERK inhibitors as a potential target therapeutic strategy with enhanced tumor growth suppression, downstream pathway blockade, and greater induction of apoptosis.

Inferring gene and protein interactions using PubMed citations and consensus Bayesian networks

The PubMed database offers an extensive set of publication data that can be useful, yet inherently complex to use without automated computational techniques. Data repositories such as the Genomic Data Commons (GDC) and the Gene Expression Omnibus (GEO) offer experimental data storage and retrieval as well as curated gene expression profiles. Genetic interaction databases, including Reactome and Ingenuity Pathway Analysis, offer pathway and experiment data analysis using data curated from these publications and data repositories. We have created a method to generate and analyze consensus networks, inferring potential gene interactions, using large numbers of Bayesian networks generated by data mining publications in the PubMed database. Through the concept of network resolution, these consensus networks can be tailored to represent possible genetic interactions. We designed a set of experiments to confirm that our method is stable across variation in both sample and topological input sizes. Using gene product interactions from the KEGG pathway database and data mining PubMed publication abstracts, we verify that regardless of the network resolution or the inferred consensus network, our method is capable of inferring meaningful gene interactions through consensus Bayesian network generation with multiple, randomized topological orderings. Our method can not only confirm the existence of currently accepted interactions, but has the potential to hypothesize new ones as well. We show our method confirms the existence of known gene interactions such as JAK-STAT-PI3K-AKT-mTOR, infers novel gene interactions such as RAS- Bcl-2 and RAS-AKT, and found significant pathway-pathway interactions between the JAK-STAT signaling and Cardiac Muscle Contraction KEGG pathways.

MicroRNAs in melanoma development and resistance to target therapy

microRNAs constitute a complex class of pleiotropic post-transcriptional regulators of gene expression involved in the control of several physiologic and pathologic processes. Their mechanism of action is primarily based on the imperfect matching of a seed region located at the 5′ end of a 21-23 nt sequence with a partially complementary sequence located in the 3′ untranslated region of target mRNAs. This leads to inhibition of mRNA translation and eventually to its degradation. Individual miRNAs are capable of binding to several mRNAs and several miRNAs are capable of influencing the function of the same mRNAs. In recent years networks of miRNAs are emerging as capable of controlling key signaling pathways responsible for the growth and propagation of cancer cells. Furthermore several examples have been provided which highlight the involvement of miRNAs in the development of resistance to targeted drug therapies. In this review we provide an updated overview of the role of miRNAs in the development of melanoma and the identification of the main downstream pathways controlled by these miRNAs. Furthermore we discuss a group of miRNAs capable to influence through their respective up- or down-modulation the development of resistance to BRAF and MEK inhibitors.

An individualized gene expression signature for prediction of lung adenocarcinoma metastases

Our laboratory previously reported an individual‐level signature consisting of nine gene pairs, named 9‐GPS. This signature was developed by training on microarray expression data and validated using three independent integrated microarray data sets, with samples of stage I non‐small‐cell lung cancer after complete surgical resection. In this study, we first validated the cross‐platform robustness of 9‐GPS by demonstrating that 9‐GPS could significantly stratify the overall survival of 213 stage I lung adenocarcinoma (LUAD) patients detected with RNA‐sequencing platform in The Cancer Genome Atlas (TCGA; log‐rank P = 0.0318, C‐index = 0.55). Applying 9‐GPS to all the 423 stage I‐IV LUAD samples in TCGA, the predicted high‐risk samples were significantly enriched with clinically diagnosed metastatic samples (Fisher's exact test, P = 0.0015). We further modified the voting rule of 9‐GPS and found that the modified 9‐GPS had a better performance in predicting metastasis states (Fisher's exact test, P < 0.0001). With the aid of the modified 9‐GPS for reclassifying the metastasis states of patients with LUAD, the reclassified metastatic samples presented clearer transcriptional and genomic characteristics compared to the reclassified nonmetastatic samples. Finally, regulator network analysis identified TP53 and IRF1 with frequent genomic aberrations in the reclassified metastatic samples, indicating their key roles in driving tumor metastasis. In conclusion, 9‐GPS is a robust signature for identifying early‐stage LUAD patients with potential occult metastasis. This occult metastasis prediction was associated with clear transcriptional and genomic characteristics as well as the clinical diagnoses.

Interactions between the tumor and the blood systemic response of breast cancer patients

Although systemic immunity is critical to the process of tumor rejection, cancer research has largely focused on immune cells in the tumor microenvironment. To understand molecular changes in the patient systemic response (SR) to the presence of BC, we profiled RNA in blood and matched tumor from 173 patients. We designed a system (MIxT, Matched Interactions Across Tissues) to systematically explore and link molecular processes expressed in each tissue. MIxT confirmed that processes active in the patient SR are especially relevant to BC immunogenicity. The nature of interactions across tissues (i.e. which biological processes are associated and their patterns of expression) varies highly with tumor subtype. For example, aspects of the immune SR are underexpressed proportionally to the level of expression of defined molecular processes specific to basal tumors. The catalog of subtype-specific interactions across tissues from BC patients provides promising new ways to tackle or monitor the disease by exploiting the patient SR.

We present a novel system (MIxT) to identify genes and pathways in the primary tumor that are tightly linked to genes and pathways in the patient systemic response (SR). These results suggest new ways to tackle and monitor the disease by looking outside the tumor and exploiting the patient SR.

Harness the synergy between targeted therapy and immunotherapy: what have we learned and where are we headed?

Since the introduction of imatinib for the treatment of chronic myelogenous leukemia, several oncogenic mutations have been identified in various malignancies that can serve as targets for therapy. More recently, a deeper insight into the mechanism of antitumor immunity and tumor immunoevasion have facilitated the development of novel immunotherapy agents. Certain targeted agents have the ability of inhibiting tumor growth without causing severe lymphocytopenia and amplifying antitumor immune response by increasing tumor antigenicity, enhancing intratumoral T cell infiltration, and altering the tumor immune microenvironment, which provides a rationale for combining targeted therapy with immunotherapy. Targeted therapy can elicit dramatic responses in selected patients by interfering with the tumor-intrinsic driver mutations. But in most cases, resistance will occur over a relatively short period of time. In contrast, immunotherapy can yield durable, albeit generally mild, responses in several tumor types via unleashing host antitumor immunity. Thus, combination approaches might be able to induce a rapid tumor regression and a prolonged duration of response. We examine the available evidence regarding immune effects of targeted therapy, and review preclinical and clinical studies on the combination of targeted therapy and immunotherapy for cancer treatment. Furthermore, we discuss challenges of the combined therapy and highlight the need for continued translational research.

Two common variants of human papillomavirus type 16 E6 differentially deregulate sugar metabolism and hypoxia signalling in permissive human keratinocytes

Human papillomavirus type 16 (HPV16) is responsible for most cancers attributable to HPV infection and naturally occurring variants of the HPV16 E6 oncoprotein predispose individuals to varying risk for developing cancer. Population studies by us and others have demonstrated that the common Asian-American E6 (AAE6) variant is a higher risk factor for cervical cancer than the E6 of another common variant, the European prototype (EPE6). However, a complete understanding of the molecular processes fundamental to these epidemiological findings is still lacking. Our previously published functional studies of these two E6 variants showed that AAE6 had a higher immortalization and transformation potential than EPE6. Proteomic analysis revealed markedly different protein patterns between these variants, especially with respect to key cellular metabolic enzymes. Here, we tested the Warburg effect and hypoxia signalling (hallmarks of cancer development) as plausible mechanisms underlying these observations. Lactate and glucose production were enhanced in AAE6-transduced keratinocytes, likely due to raised levels of metabolic enzymes, but independent of hypoxia-inducible factor 1 alpha (HIF-1α) activity. The HIF-1α protein level and activity were elevated by AAE6 in hypoxic conditions, leading to a hypoxia-tolerant phenotype with enhanced migratory potential. The deregulation of HIF-1α was caused by the AAE6 variant's ability to augment mitogen-activated protein kinase/extracellular related kinase signalling. The present study reveals prominent underlying mechanisms of the AAE6's enhanced oncogenic potential.

Thiol-reducing agents prevent sulforaphane-induced growth inhibition in ovarian cancer cells

The inhibitory potential of sulforaphane against cancer has been suggested for different types of cancer, including ovarian cancer. We examined whether this effect is mediated by mitogen-activated protein kinase (MAPK) and reactive oxygen species (ROS), important signaling molecules related to cell survival and proliferation, in ovarian cancer cells. Sulforaphane at a concentration of 10 μM effectively inhibited the growth of cancer cells. Use of specific inhibitors revealed that activation of MAPK pathways by sulforaphane is unlikely to mediate sulforaphane-induced growth inhibition. Sulforaphane did not generate significant levels of intracellular ROS. Pretreatment with thiol reducers, but not ROS scavengers, prevented sulforaphane-induced growth inhibition. Furthermore, diamide, a thiol-oxidizing agent, enhanced both growth inhibition and cell death induced by sulforaphane, suggesting that the effect of sulforaphane on cell growth may be related to oxidation of protein thiols or change in cellular redox status. Our data indicate that supplementation with thiol-reducing agents should be avoided when sulforaphane is used to treat cancer.

Combined targeting of Arf1 and Ras potentiates anticancer activity for prostate cancer therapeutics

Background

Although major improvements have been made in surgical management, chemotherapeutic, and radiotherapeutic of prostate cancer, many prostate cancers remain refractory to treatment with standard agents. Therefore, the identification of new molecular targets in cancer progression and development of novel therapeutic strategies to target them are very necessary for achieving better survival for patients with prostate cancer. Activation of small GTPases such as Ras and Arf1 is a critical component of the signaling pathways for most of the receptors shown to be upregulated in advanced prostate cancer.

Methods

The drug effects on cell proliferation were measured by CellTiter 96® AQueous One Solution Cell Proliferation Assay. The drug effects on cell migration and invasion were determined by Radius™ 24-well and Matrigel-coated Boyden chambers. The drug effects on apoptosis were assessed by FITC Annexin V Apoptosis Detection Kit with 7-AAD and Western blot with antibodies against cleaved PARP and Caspase 3. A NOD/SCID mouse model generated by subcutaneous injection was used to assess the in vivo drug efficacy in tumor growth. ERK activation and tumor cell proliferation in xenografts were examined by immunohistochemistry.

Results

We show that Exo2, a small-molecule inhibitor that reduces Arf1 activation, effectively suppresses prostate cancer cell proliferation by blocking ERK1/2 activation. Exo2 also has other effects, inhibiting migration and invasion of PCa cells and inducing apoptosis. The Ras inhibitor salirasib augments Exo2-induced cytotoxicity in prostate cancer cells partially by enhancing the suppression of ERK1/2 phosphorylation. In a xenograft mouse model of prostate cancer, Exo2 reduces prostate tumor burden and inhibits ERK1/2 activation at a dose of 20 mg/kg. Synergistic treatment of salirasib and Exo2 exhibits a superior inhibitory effect on prostate tumor growth compared with either drug alone, which may be attributed to the more efficient inhibition of ERK1/2 phosphorylation.

Conclusion

This study suggests that simultaneous blockade of Arf1 and Ras activation in prostate cancer cells is a potential targeted therapeutic strategy for preventing prostate cancer development.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0583-4) contains supplementary material, which is available to authorized users.

The MEK inhibitor selumetinib complements CTLA-4 blockade by reprogramming the tumor immune microenvironment

Background

T-cell checkpoint blockade and MEK inhibitor combinations are under clinical investigation. Despite progress elucidating the immuno-modulatory effects of MEK inhibitors as standalone therapies, the impact of MEK inhibition on the activity of T-cell checkpoint inhibitors remains incompletely understood. Here we sought to characterize the combined effects of MEK inhibition and anti-CTLA-4 mAb (anti-CTLA-4) therapy, examining effects on both T-cells and tumor microenvironment (TME).

Methods

In mice, the effects of MEK inhibition, via selumetinib, and anti-CTLA-4 on immune responses to keyhole limpet haemocyanin (KLH) immunization were monitored using ex vivo functional assays with splenocytes. In a KRAS-mutant CT26 mouse colorectal cancer model, the impact on the tumor microenvironment (TME) and the spleen were evaluated by flow cytometry. The TME was further examined by gene expression and immunohistochemical analyses. The combination and sequencing of selumetinib and anti-CTLA-4 were also evaluated in efficacy studies using the CT26 mouse syngeneic model.

Results

Anti-CTLA-4 enhanced the generation of KLH specific immunity following KLH immunization in vivo; selumetinib was found to reduce, but did not prevent, this enhancement of immune response by anti-CTLA-4 in vivo. In the CT26 mouse model, anti-CTLA-4 treatment led to higher expression levels of the immunosuppressive mediators, Cox-2 and Arg1 in the TME. Combination of anti-CTLA-4 with selumetinib negated this up-regulation of Cox-2 and Arg1, reduced the frequency of CD11⁺ Ly6G⁺ myeloid cells, and led to the accumulation of differentiating monocytes at the Ly6C⁺ MHC⁺ intermediate state in the tumor. We also report that MEK inhibition had limited impact on anti-CTLA-4-mediated increases in T-cell infiltration and T-cell activation in CT26 tumors. Finally, we show that pre-treatment, but not concurrent treatment, with selumetinib enhanced the anti-tumor activity of anti-CTLA-4 in the CT26 model.

Conclusion

These data provide evidence that MEK inhibition can lead to changes in myeloid cells and immunosuppressive factors in the tumor, thus potentially conditioning the TME to facilitate improved response to anti-CTLA-4 treatment. In summary, the use of MEK inhibitors to alter the TME as an approach to enhance the activities of immune checkpoint inhibitors warrants further investigation in clinical trials.

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-017-0268-8) contains supplementary material, which is available to authorized users.

Influence and mechanism of 5-aminolevulinic acid-photodynamic therapy on the metastasis of esophageal carcinoma

BACKGROUD

Photodynamic therapy (PDT) for the treatment of esophageal cancer was more and more popularly used since it was approved for the treatment of advanced esophageal cancer in 1996. It has been reported to influence the tumor growth and metastasis via a variety of signaling pathways, but its mechanism remains to be further studied. This research studied the effects of ALA-PDT on esophageal carcinoma in vitro and in vivo, discovering its molecular regulating mechanism and the way to enhence the PDT effect.

METHODS

Eca-109 cells were incubated with a medium containing EGFR tyrphostin AG1478 or PI3K inhibitor LY294002, then with ALA, and the cells were irradiated with the laser 6h later. The cell viability was measured with MTT assay, and the migration ability was detected by transwell experiments 24h post-ALA-PDT. The gene and protein expression on EGFR/PI3K/AKT signaling pathway was analyzed by realtime PCR and Western blotting respectively. Then, RFP-Eca-109 burdened nude mice model was constructed, and were treated with ALA-PDT when the tumor volume reached 150-350mm³. The gene and protein expression were analyzed 24h and 50days post-ALA-PDT.

RESULTS

Our study showed that ALA-PDT respectively combined with AG1478, LY294002 could synergistically reduce the growth and migration ability of the Eca-109 cells in vitro and significantly down-regulate the protein expression of EGFR/PI3K and PI3K/AKT, meanwhile, significantly down-regulate the gene expression of EGFR when combining with AG1478. Forthermore, ALA-PDT could significantly decrease the tumor growth and metastasis and down-regulate the gene expression of EGFR and the protein expression of EGFR and PI3K in the tumor of mice.

CONCLUSION

This study revealed a molecular mechanism of ALA-PDT and developed a new modality application of therapy, by combining ALA-PDT with small molecular inhibitors, for better effect in the clinical practice of esophageal carcinoma.

Somatic Host Cell Alterations in HPV Carcinogenesis

High-risk human papilloma virus (HPV) infections cause cancers in different organ sites, most commonly cervical and head and neck cancers. While carcinogenesis is initiated by two viral oncoproteins, E6 and E7, increasing evidence shows the importance of specific somatic events in host cells for malignant transformation. HPV-driven cancers share characteristic somatic changes, including apolipoprotein B mRNA editing catalytic polypeptide-like (APOBEC)-driven mutations and genomic instability leading to copy number variations and large chromosomal rearrangements. HPV-associated cancers have recurrent somatic mutations in phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and phosphatase and tensin homolog (PTEN), human leukocyte antigen A and B (HLA-A and HLA-B)-A/B, and the transforming growth factor beta (TGFβ) pathway, and rarely have mutations in the tumor protein p53 (TP53) and RB transcriptional corepressor 1 (RB1) tumor suppressor genes. There are some variations by tumor site, such as NOTCH1 mutations which are primarily found in head and neck cancers. Understanding the somatic events following HPV infection and persistence can aid the development of early detection biomarkers, particularly when mutations in precancers are characterized. Somatic mutations may also influence prognosis and treatment decisions.

Synergistic anti-tumor effect of 17AAG with the PI3K/mTOR inhibitor NVP-BEZ235 on human melanoma

Drug resistance by MAPK signaling recovery or activation of alternative signaling pathways, such as PI3K/AKT/mTOR, is an important factor that limits the long-term efficacy of targeted therapies in melanoma patients. In the present study, we investigated the phospho-proteomic profile of RTKs and its correlation with downstream signaling pathways in human melanoma. We found that tyrosine kinase receptors expression correlated with the expression of pivotal downstream components of the RAS/RAF/MAPK and PI3K/AKT/mTOR pathways in melanoma cell lines and tumors. We also found high expression of HSP90 and the PI3K/AKT/mTOR pathway proteins, 4EBP1 and AKT compared with healthy tissue and this correlated with poor overall survival of melanoma patients. The combination of the HSP90 inhibitor 17AAG with the PI3K/mTOR inhibitor NVP-BEZ235 showed a synergistic activity decreasing melanoma cell growth, inducing apoptosis and targeting simultaneously the MAPK and PI3K/AKT/mTOR pathways. These results demonstrate that the combination of HSP90 and PI3K/mTOR inhibitors could be an effective therapeutic strategy that target the main survival pathways in melanoma and must be considered to overcome resistance to BRAF inhibitors in melanoma patients.

Altered Protein Interactions of the Endogenous Interactome of PTPIP51 towards MAPK Signaling

Protein-protein interactions play a pivotal role in normal cellular functions as well as in carcinogenesis. The protein-protein interactions form functional clusters during signal transduction. To elucidate the fine calibration of the protein-protein interactions of protein tyrosine phosphatase interacting protein 51 (PTPIP51) a small molecule drug, namely LDC-3, directly targeting PTPIP51 is now available. Therefore, LDC-3 allows for the studying of the regulation of the endogenous interactome by modulating PTPIP51 binding capacity. Small interfering ribonucleic acid (siRNA) experiments show that the modification in PTPIP51 binding capacity is induced by LDC-3. Application of LDC-3 annuls the known regulatory phosphorylation mechanisms for PTPIP51 and consequently, significantly alters the assembly of the PTPIP51 associated protein complexes. The treatment of human keratinocytes (HaCaT cells) with LDC-3 induces an altered protein-protein interaction profile of the endogenous interactome of PTPIP51. In addition, LDC-3 stabilizes PTPIP51 within a mitogen activated protein kinase (MAPK) complex composed of Raf-1 and the scaffold protein 14-3-3, independent of the phosphorylation status of PTPIP51. Of note, under LDC-3 treatment the regulatory function of the PTP1B on PTPIP51 fails to impact the PTPIP51 interaction characteristics, as reported for the HaCaT cell line. In summary, LDC-3 gives the unique opportunity to directly modulate PTPIP51 in malignant cells, thus targeting potential dysregulated signal transduction pathways such as the MAPK cascade. The provided data give critical insights in the therapeutic potential of PTPIP51 protein interactions and thus are basic for possible targeted therapy regimens.

Genetics of Short Stature

Short stature is a common and heterogeneous condition that is often genetic in etiology. For most children with genetic short stature, the specific molecular causes remain unknown; but with advances in exome/genome sequencing and bioinformatics approaches, new genetic causes of growth disorders have been identified, contributing to the understanding of the underlying molecular mechanisms of longitudinal bone growth and growth failure. Identifying new genetic causes of growth disorders has the potential to improve diagnosis, prognostic accuracy, and individualized management, and help avoid unnecessary testing for endocrine and other disorders.

Dysregulation of angiogenesis-specific signalling in adult testis results in xenograft degeneration

Ectopic xenografting of testis is a feasible option for preservation of male fertility and angiogenesis plays a pivotal role in xenograft survival and functionality. When compared to immature testis, the adult testis is unable to establish functional xenografts due to potentially lower efficiency to induce angiogenesis. The precise molecular mechanism, however, remains elusive. In the present study, we compared adult and immature testis xenografts for survival, maturation and germ cell differentiation. Further, we evaluated differential expression of angiogenesis signalling-specific proteins in adult and immature testis and their xenografts. Results showed that adult testis xenografts degenerated whereas immature testis xenografts survived and established spermatogenesis with the production of haploid germ cells. Protein expression analysis demonstrated that immature testis xenografts were able to establish angiogenesis either through eNOS activation via VEGF and PI3K/AKT or through EGFR-mediated STAT3 pathway. The role of ERK/MAPK pathway in xenograft angiogenesis was ruled out. The absence or reduced expression of angiogenesis-specific proteins in adult testis and its xenografts possibly resulted in poor angiogenesis and in their subsequent degeneration. This study provides insight into angiogenesis mechanism that can be utilized to augment testis xenografting efficiency.

mTOR activation is increased in pilocytic astrocytomas from older adults compared with children

BACKGROUND

Recent studies suggest that the behavior and biology of WHO grade I pilocytic astrocytomas (PAs) in adults is different than that associated with grade I PAs in children.

METHODS

We evaluated Ki-67 labeling, BRAF abnormalities, isocitrate dehydrogenase R132 immunoreactivity phosphorylation (activation) of p44/42 mitogen activated protein kinase (MAPK), and mammalian target of rapamycin (mTOR) in formalin-fixed tissue from 21 adult (18 years or older, mean age 37 years) and 10 children (mean age 9.4 years) WHO grade I PAs.

RESULTS

The mean Ki-67 labeling was 4.8% in adults and 3.8% in children. There was no significant difference between Ki-67 labeling in children and adults or either subgroups of adults. No differences were found in phospho p44/42MAPK in adult subgroups (18-33 years and 34 and older) compared to children. Activation/phosphorylation of mTOR was biphasic in adults being significantly lower than children in young adults but significantly higher than children in older adults (age 34 and older).

CONCLUSIONS

Identifying mTOR phosphorylation/activation may represent a difference in biology and a new marker to guide chemotherapy with recently approved mTOR inhibitors.

hrHPV E5 oncoprotein: immune evasion and related immunotherapies

The immune response is a key factor in the fight against HPV infection and related cancers, and thus, HPV is able to promote immune evasion through the expression of oncogenes. In particular, the E5 oncogene is responsible for modulation of several immune mechanisms, including antigen presentation and inflammatory pathways. Moreover, E5 was suggested as a promising therapeutic target, since there is still no effective medical therapy for the treatment of HPV-related pre-neoplasia and cancer. Indeed, several studies have shown good prospective for E5 immunotherapy, suggesting that it could be applied for the treatment of pre-cancerous lesions. Thus, insofar as the majority of cervical, oropharyngeal and anal cancers are caused by high-risk HPV (hrHPV), mainly by HPV16, the aim of this review is to discuss the immune pathways interfered by E5 oncoprotein of hrHPV highlighting the various aspects of the potential immunotherapeutic approaches.

Inhibition of the PI3K/AKT/mTOR pathway activates autophagy and compensatory Ras/Raf/MEK/ERK signalling in prostate cancer

The PI3K/AKT/mTOR pathway is frequently activated in advanced prostate cancer, due to loss of the tumour suppressor PTEN, and is an important axis for drug development. We have assessed the molecular and functional consequences of pathway blockade by inhibiting AKT and mTOR kinases either in combination or as individual drug treatments. In established prostate cancer cell lines, a decrease in cell viability and in phospho-biomarker expression was observed. Although apoptosis was not induced, a G1 growth arrest was observed in PTEN null LNCaP cells, but not in BPH1 or PC3 cells. In contrast, when the AKT inhibitor AZD7328 was applied to patient-derived prostate cultures that retained expression of PTEN, activation of a compensatory Ras/MEK/ERK pathway was observed. Moreover, whilst autophagy was induced following treatment with AZD7328, cell viability was less affected in the patient-derived cultures than in cell lines. Surprisingly, treatment with a combination of both AZD7328 and two separate MEK1/2 inhibitors further enhanced phosphorylation of ERK1/2 in primary prostate cultures. However, it also induced irreversible growth arrest and senescence.

Ex vivo treatment of a patient-derived xenograft (PDX) of prostate cancer with a combination of AZD7328 and the mTOR inhibitor KU-0063794, significantly reduced tumour frequency upon re-engraftment of tumour cells.

The results demonstrate that single agent targeting of the PI3K/AKT/mTOR pathway triggers activation of the Ras/MEK/ERK compensatory pathway in near-patient samples. Therefore, blockade of one pathway is insufficient to treat prostate cancer in man.

AKT is critically involved in the antagonism of BRAF inhibitor sorafenib against dabrafenib in colorectal cancer cells harboring both wild-type and mutant (V600E) BRAF genes

BRAF, one of the key factors in mitogen-activated protein kinase (MAPK) signaling pathway, plays an important role in cell functions including growth and proliferation. Inhibition of BRAF represents a promising antitumor strategy. Dabrafenib, a type I inhibitor of BRAF interrupting RAF/MEK interaction, has been approved by FDA as a single agent or combined with MEK inhibitor trametinib for the treatment of patients with BRAF V600E mutation-positive advanced melanoma. In the present study, we investigated the feasibility of combined treatment with dabrafenib and sorafenib, type I and type II BRAF inhibitor respectively, on colorectal cancer cells with BRAF V600E mutation. Unexpectedly, sorafenib significantly antagonized the inhibition effect of dabrafenib on the proliferation of colorectal cancer HT-29 and Colo205 cells. The antagonism relied on co-existence of wild-type and mutant (V600E) BRAF, for no antagonism was observed in tumor cells expressing homozygous wild-type or mutant (V600E) BRAF. BRAF, but not CRAF, was required for this antagonism. Moreover, we found that sorafenib reversed dabrafenib inhibition of AKT in HT-29 cells, and phosphatidylinositol-3-kinase (PI3K) inhibitor GDC0941 significantly restored this antagonistic effect when combined with dabrafenib and sorafenib, indicating that AKT is critically involved in this antagonism. Collectively, we found that significant antagonism was observed when dabrafenib was combined with sorafenib in colorectal cancer cells harboring heterozygous genotype of BRAF and AKT is critically involved in this antagonism. We suggest that BRAF inhibitor dabrafenib and sorafenib should not be combined in clinic.

Peripheral blood mononuclear cells from rat model of pleurisy: The effects of hesperidin on ectoenzymes activity, apoptosis, cell cycle and reactive oxygen species production

The present study investigates the effect of hesperidin; a flavonone commonly found in citrus fruits, on the ectoenzymes (ectonucleotidase and ecto-adenosine deaminase) activity, cell viability, apoptosis, cell cycle arrest and reactive oxygen species production in peripheral blood mononuclear cells (PBMCs) from rat model of pleurisy. Wistar rats were pretreated with either saline or hesperidin (80mg/kg) by oral gavage for 21days and injected intrapleurally with 2% carrageenan or saline on the 22nd day. PBMCs were subsequently prepared after 4h of carrageenan induction. The results revealed that hesperidin may exhibit its anti-inflammatory effects through possible modulation of ectonucleotidase (E-NTPDase) and ecto-adenosine deaminase (E-ADA) activities, reduction of intracellular reactive oxygen species, prevention of DNA damage and modulation of apoptosis as well as activation of cell cycle arrest. This study suggests some possible underlying anti-inflammatory mechanisms of hesperidin on PBMCs in acute inflammatory condition. Furthermore, hesperidin may minimize oxidative injury mediated pleurisy in rat.

Autism spectrum disorder and other neurobehavioural comorbidities in rare disorders of the Ras/MAPK pathway

AIM

To investigate the cognitive and behavioural phenotype in rare disorders of the Ras/MAPK pathway, namely Noonan, cardiofaciocutaneous (CFC), and Costello syndromes, particularly prevalence of autism spectrum disorder (ASD) and attention-deficit-hyperactivity disorder (ADHD).

METHOD

Fifty children were recruited over 10 months through the regional genetics service and advertisements. A range of parent, child, and observational measures were administered including Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Scale.

RESULTS

Using the Collaborative Programme for Excellence in Autism criteria, 12 out of 40 children with Noonan syndrome (30%) showed ASD, and 12 out of 40 (30%) with partial ASD features and 16 out of 40 (40%) showed non-ASD. The Noonan syndrome ASD group showed male dominance in a ratio of 5:1. In the CFC group, eight out of nine children met the criteria for ASD, with equal sex distribution. Additionally 19 out of 40 (48%) of the Noonan syndrome group and eight out of nine (88.9%) of the CFC group scored met clinical criteria for ADHD. Only one child was in the Costello syndrome group.

INTERPRETATION

This is the first systematic study to suggest a high prevalence of ASD in Noonan and CFC syndromes, and thus offers crucial evidence to support the importance of the Ras/MAPK pathway in the aetiology of ASD. Limitations include the inevitable possibility of a sampling bias in a rare disorder study of this kind.

mTORC1 senses stresses: Coupling stress to proteostasis

Beyond protein synthesis and autophagy, emerging evidence has implicated mTORC1 in regulating protein folding and proteasomal degradation as well, highlighting its prominent role in cellular proteome homeostasis or proteostasis. In addition to growth signals, mTORC1 senses and responds to a wide array of stresses, including energetic/metabolic stress, genotoxic stress, oxidative stress, osmotic stress, ER stress, proteotoxic stress, and psychological stress. Whereas growth signals unanimously stimulate mTORC1, stresses exert complex impacts on mTORC1, most of which are repressive. mTORC1 suppression, as a generic adaptive strategy, empowers cell survival under various stressful conditions. In this essay, we provide an overview of the emerging role of mTORC1 in proteostasis, the distinct molecular mechanisms through which mTORC1 reacts to diverse stresses, and the schemes exploited by cancer cells to circumvent stress-induced mTORC1 suppression. Hence, acting as a stress sensor, mTORC1 intimately couples stresses to cellular proteostasis.

Epidermal growth factor receptor (EGFR)-MAPK-nuclear factor(NF)-κB-IL8: A possible mechanism of particulate matter(PM) 2.5-induced lung toxicity

Airway inflammation plays a central role in the pathophysiology of diverse pulmonary diseases. In this study, we investigated whether exposure to particulate matter (PM) 2.5, a PM with an aerodynamic diameter of less than 2.5 µm, enhances inflammation-related toxicity in the human respiratory system through activation of the epidermal growth factor receptor (EGFR) signaling pathway. Through cytokine antibody array analysis of two extracts of PM_2.5 [water (W-PM_2.5 ) and organic (O-PM_2.5 ) soluble extracts] exposed to A549 (human alveolar epithelial cell), we identified eight cytokines changed their expression with W-PM_2.5 and three cytokines with O-PM_2.5 . Among them, epidermal growth factor (EGF) was commonly up-regulated by W-PM_2.5 and O-PM_2.5 . Then, in both groups, we can identify the increase in EGF receptor protein levels. Likewise, increases in the phosphorylation of ERK1/2 MAP kinase and acetylation of nuclear factor(NF)-κB were detected. We also detected an increase in IL-8 that was related to inflammatory response. And using the erlotinib as an inhibitor of EGFR, we identified the erlotinib impaired the phosphorylation of EGFR, ERK1/2, acetylation of NF-κB proteins and decreased IL-8. Furthermore, at in vivo model, we were able to identify similar patterns. These results suggest that PM_2.5 may contribute to an abnormality in the human respiratory system through EGFR, MAP kinase, NF-κB, and IL-8 induced toxicity signaling. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1628-1636, 2017.

mTORC1 senses stresses: Coupling stress to proteostasis

Beyond protein synthesis and autophagy, emerging evidence has implicated mTORC1 in regulating protein folding and proteasomal degradation as well, highlighting its prominent role in cellular proteome homeostasis or proteostasis. In addition to growth signals, mTORC1 senses and responds to a wide array of stresses, including energetic/metabolic stress, genotoxic stress, oxidative stress, osmotic stress, ER stress, proteotoxic stress, and psychological stress. Whereas growth signals unanimously stimulate mTORC1, stresses exert complex impacts on mTORC1, most of which are repressive. mTORC1 suppression, as a generic adaptive strategy, empowers cell survival under various stressful conditions. In this essay, we provide an overview of the emerging role of mTORC1 in proteostasis, the distinct molecular mechanisms through which mTORC1 reacts to diverse stresses, and the schemes exploited by cancer cells to circumvent stress-induced mTORC1 suppression. Hence, acting as a stress sensor, mTORC1 intimately couples stresses to cellular proteostasis.

Reduction-oxidation pathways involved in cancer development: a systematic review of literature reviews

Oxidative stress results from an imbalance of the reactive oxygen species/reactive nitrogen species (ROS/RNS) production and the oxidants defense system. Extensive research during the last decades has revealed that oxidative stress can mediate cancer initiation and development by leading not only to molecular damage but also to a disruption of reduction-oxidation (redox) signaling. In order to provide a global overview of the redox signaling pathways, which play a role in cancer formation, we conducted a systematic literature search in PubMed and ISI Web of Science and identified 185 relevant reviews published in the last 10 years. The 20 most frequently described pathways were selected to be presented in this systematic review and could be categorized into 3 groups: Intracellular ROS/RNS generating organelles and enzymes, signal transduction cascades kinases/phosphatases and transcription factors. Intracellular ROS/RNS generation organelles are mitochondria, endoplasmic reticulum and peroxisomes. Enzymes, including NOX, COX, LOX and NOS, are the most prominent enzymes generating ROS/RNS. ROS/RNS act as redox messengers of transmembrane receptors and trigger the activation or inhibition of signal transduction kinases/phosphatases, such as the family members of protein tyrosine kinases and protein tyrosine phosphatases. Furthermore, these reactions activate downstream signaling pathways including protein kinase of the MAPK cascade, PI3K and PKC. The kinases and phosphatases regulate the phosphorylation status of transcription factors including APE1/Ref-1, HIF-1α, AP-1, Nrf2, NF-κB, p53, FOXO, STAT, and β-catenin. Finally, we briefly discuss cancer prevention and treatment opportunities, which address redox pathways and further research needs.

Evaluation of the use of therapeutic peptides for cancer treatment

Cancer along with cardiovascular disease are the main causes of death in the industrialised countries around the World. Conventional cancer treatments are losing their therapeutic uses due to drug resistance, lack of tumour selectivity and solubility and as such there is a need to develop new therapeutic agents. Therapeutic peptides are a promising and a novel approach to treat many diseases including cancer. They have several advantages over proteins or antibodies: as they are (a) easy to synthesise, (b) have a high target specificity and selectivity and (c) have low toxicity. Therapeutic peptides do have some significant drawbacks related to their stability and short half-life. In this review, strategies used to overcome peptide limitations and to enhance their therapeutic effect will be compared. The use of short cell permeable peptides that interfere and inhibit protein-protein interactions will also be evaluated.

Metastatic BRAF K601E-mutated melanoma reaches complete response to MEK inhibitor trametinib administered for over 36 months

BACKGROUND

The BRAF K601E mutation occurs in 5% of patients with melanoma, and is the third most common type of BRAF mutation. However, treatment with BRAF and mitogen-activated extracellular signal-regulated kinase (MEK) inhibitors is only approved in patients with BRAF V600-positive melanoma, and patients with K601E-mutated melanoma do not have access to such drugs.

CASE PRESENTATION

A female patient was diagnosed with high tumor burden metastatic melanoma harboring the BRAF K601E mutation. After chemotherapy failure, she underwent compassionate treatment with trametinib. Trametinib showed good activity and efficacy, with 48% shrinkage of a metastatic lymphadenopathy after 4 months' treatment. However, the patient reported treatment-related skin toxicity that required dosage reduction and a personalized intermittent trametinib dosing schedule. After over 36 months from the first trametinib administration, and resection of a metastatic lymphadenopathy, the patient experienced complete response.

CONCLUSIONS

This case report shows that trametinib could be a valid therapeutic option in patients with metastatic melanoma harboring the rare BRAF K601E mutation.

Strategies for Overcoming Resistance in Tumours Harboring BRAF Mutations

The development of resistance to previously effective treatments has been a challenge for health care providers and a fear for patients undergoing cancer therapy. This is an unfortunately frequent occurrence for patients undergoing targeted therapy for tumours harboring the activating V600E mutation of the BRAF gene. Since the initial identification of the BRAF mutation in 2002, a series of small molecular inhibitors that target the BRAFV600E have been developed, but intrinsic and acquired resistance to these drugs has presented an ongoing challenge. More recently, improvements in therapy have been achieved by combining the use of BRAF inhibitors with other drugs, such as inhibitors of the downstream effector mitogen activated protein kinase (MAPK)/extracellular-signal regulated kinase (ERK) kinase (MEK). Despite improved success in response rates and in delaying resistance using combination therapy, ultimately, the acquisition of resistance remains a concern. Recent research articles have shed light on some of the underlying mechanisms of this resistance and have proposed numerous strategies that might be employed to overcome or avoid resistance to targeted therapies. This review will explore some of the resistance mechanisms, compare what is known in melanoma cancer to colorectal cancer, and discuss strategies under development to manage the development of resistance.

Study of the expression and function of ACY1 in patients with colorectal cancer

Aminoacylase 1 (ACY1) is important for regulating the proliferation of numerous types of cancer. However, the expression and mechanisms underlying the function of ACY1 in colorectal cancer remain unclear. In order to investigate the expression and function of ACY1 in colorectal cancer, tumor tissue and blood samples were collected for analysis from 132 patients diagnosed with colorectal cancer. Reverse transcription-quantitative polymerase chain reaction analysis and western blotting identified significantly increased expression of ACY1 mRNA in colorectal tumor tissue (P<0.05 vs. adjacent normal tissue) and notably increased ACY1 protein levels. This ACY1 mRNA expression was found to be positively correlated with tumor stage. In addition, plasma ACY1 concentration was increased in patients with colorectal cancer compared with healthy controls. Furthermore, in vitro knockdown of ACY1 in human colorectal cancer HT-29 cells was shown to inhibit proliferation and increase apoptosis. This effect was found to be associated with the activation of ERK1 and TGF-β1 signaling. In conclusion, the results of the present study suggest that ACY1 promotes tumor progression, and thus may be a potential target for the diagnosis and treatment of colorectal cancer.

miR182 activates the Ras-MEK-ERK pathway in human oral cavity squamous cell carcinoma by suppressing RASA1 and SPRED1

Purpose

The constitutive activation of the Ras–MEK–ERK signaling pathway in oral cavity squamous cell carcinoma (OSCC) has been found to be tightly controlled at multiple levels under physiological conditions. RASA1 and SPRED1 are two important negative regulators of this pathway, but the exact regulating mechanism remains unclear. In this study, we aimed to explore the potential regulating mechanisms involved in the Ras–MEK–ERK signaling pathway in OSCC.

Materials and methods

MicroRNA (miRNA) expression was detected by quantitative reverse-transcription polymerase chain reaction. The protein levels of RASA1, SPRED1, and signaling proteins were detected by Western blot. Cell growth was determined using CCK-8 reagent, colony formation was stained by crystal violet, and cell invasion was tested using transwell chambers. Cell apoptosis and the cell cycle were then analyzed by flow cytometry. The binding of miR182 with RASA1 or SPRED1 was evaluated by luciferase reporter assays on a dual-luciferase reporter system.

Results

The expression of miR182 was found to be upregulated significantly in malignant oral carcinoma tissues compared with the adjacent nonmalignant tissues, and was inversely correlated with protein levels of RASA1 and SPRED1. Overexpression of miR182 in OSCC cell lines sustained Ras–MEK–ERK signaling-pathway activation, and promoted cell proliferation, cell-cycle progression, colony formation, and invasion capacity, whereas miR182 downregulation alleviated these properties significantly in vitro. Furthermore, we demonstrated that miR182 exerted its oncogenic role in OSCC by directly targeting and suppressing RASA1 and SPRED1.

Conclusion

Our results bring new insights into the important role of miR182 in the activation of the Ras–MEK–ERK signaling pathway, and suggest that miR182 may be used as a potential target for treatment of OSCC, prompting further investigation into miRNA antisense oligonucleotides for cancer therapy.

Circular RNA ciRS-7-A Promising Prognostic Biomarker and a Potential Therapeutic Target in Colorectal Cancer

Purpose: Colorectal cancer is one of the most common malignancies worldwide. Recently, a novel circular RNA, ciRS-7, was proposed to be a potential miR-7 sponge. As miR-7, a putative tumor-suppressor, regulates the expression of several important drivers of colorectal cancer, we analyzed the clinical significance of ciRS-7 in colorectal cancer patients.Experimental Design: Initially, we evaluated the expression levels of ciRS-7 in a training cohort comprising of 153 primary colorectal cancer tissues and 44 matched normal mucosae. We subsequently confirmed its clinical relevance in an independent validation cohort (n = 165), and evaluated the effect of ciRS-7 on miR-7, and its target genes EGFR and RAF1. Functional analyses were performed in cell lines and an animal model to support clinical findings.Results: Our data revealed that ciRS-7 was significantly upregulated in colorectal cancer tissues compared with matched normal mucosae (P = 0.0018), and its overexpression was associated with poor patient survival (P = 0.0224 and 0.0061 in the training and validation cohorts, respectively). Multivariate survival analysis revealed that ciRS-7 emerged as an independent risk factor for overall survival (P = 0.0656 and 0.0324 in the training and validation cohorts, respectively). Overexpression of ciRS-7 in HCT116 and HT29 cells led to the blocking of miR-7 and resulted in a more aggressive oncogenic phenotype, and ciRS-7 overexpression permitted the inhibition of miR-7 and subsequent activation of EGFR and RAF1 oncogenes.Conclusions: CiRS-7 is a promising prognostic biomarker in colorectal cancer patients and may serve as a therapeutic target for reducing EGFR-RAF1 activity in colorectal cancer patients. Clin Cancer Res; 23(14); 3918-28. ©2017 AACR.