VEGF blockade enhances the antitumor effect of BRAFV600E inhibition

BRAF Inhibitors in Metastatic Colorectal Cancer and Mechanisms of Resistance: A Review of the Literature

Metastatic colorectal cancer (mCRC) with mutated BRAF exhibits distinct biological and molecular features that set it apart from other subtypes of CRC. Current standard treatment for these tumors involves a combination of chemotherapy (CT) and VEGF inhibitors. Recently, targeted therapy against BRAF and immunotherapy (IT) for cases with microsatellite instability (MSI) have been integrated into clinical practice. While targeted therapy has shown promising results, resistance to treatment eventually develops in a significant portion of responsive patients. This article aims to review the available literature on mechanisms of resistance to BRAF inhibitors (BRAFis) and potential therapeutic strategies to overcome them.

Design, Synthesis, and Biological Evaluation of Indole-2-carboxamides as Potential Multi-Target Antiproliferative Agents

A small set of indole-based derivatives, IV and Va-I, was designed and synthesized. Compounds Va-i demonstrated promising antiproliferative activity, with GI₅₀ values ranging from 26 nM to 86 nM compared to erlotinib's 33 nM. The most potent antiproliferative derivatives-Va, Ve, Vf, Vg, and Vh-were tested for EGFR inhibitory activity. Compound Va demonstrated the highest inhibitory activity against EGFR with an IC₅₀ value of 71 ± 06 nM, which is higher than the reference erlotinib (IC₅₀ = 80 ± 05 nM). Compounds Va, Ve, Vf, Vg, and Vh were further tested for BRAF^V600E inhibitory activity. The tested compounds inhibited BRAF^V600E with IC₅₀ values ranging from 77 nM to 107 nM compared to erlotinib's IC₅₀ value of 60 nM. The inhibitory activity of compounds Va, Ve, Vf, Vg, and Vh against VEGFR-2 was also determined. Finally, in silico docking experiments attempted to investigate the binding mode of compounds within the active sites of EGFR, BRAF^V600E, and VEGFR-2.

Treatment of BRAF-V600E mutant metastatic colorectal cancer: new insights and biomarkers

INTRODUCTION

The presence of a BRAF-V600E mutation in metastatic colorectal cancer (mCRC) is observed in approximately 12% of cases and is associated with poor prognosis and aggressive disease. Unlike melanoma, the development of successful BRAF blockade in colorectal cancer has been complex. The phase III BEACON trial made significant progress in the development of BRAF inhibitors by establishing encorafenib-cetuximab as the new standard of care for patients with mCRC who have progressed to one or two previous lines of treatment. Nonetheless, not all patients respond to encorafenib-based combinations, and some responses are short-lived. Identifying new strategies to boost antitumor activity and improve survival is paramount.

AREAS COVERED

The development of targeted therapy for BRAF-V600E mCRC starting with BRAF inhibitors as monotherapy through novel combinations with anti-VEGF or anti-PD1 agents to enhance antitumor activity is reviewed, with a particular focus on the development of predictive and prognostic biomarkers.

EXPERT OPINION

There is a crucial need to better understand tumor biology and develop accurate and reliable biomarkers to enhance the antitumor activity of encorafenib-based combinations. The RNF43 mutation is an accurate and reliable predictive biomarker of response, and combinations that target crosstalk between the MAPK pathway, the immune system, and WNT pathways seem promising.

Kinetics of RTK activation determine ERK reactivation and resistance to dual BRAF/MEK inhibition in melanoma

The combination of BRAF and MEK inhibitors (BRAFi/MEKi) has shown promising response rates in treating BRAF-mutant melanoma by inhibiting ERK activation. However, treatment efficacy is limited by the emergence of drug-tolerant persister cells (persisters). Here, we show that the magnitude and duration of receptor tyrosine kinase (RTK) activation determine ERK reactivation and persister development. Our single-cell analysis reveals that only a small subset of melanoma cells exhibits effective RTK and ERK activation and develops persisters, despite uniform external stimuli. The kinetics of RTK activation directly influence ERK signaling dynamics and persister development. These initially rare persisters form major resistant clones through effective RTK-mediated ERK activation. Consequently, limiting RTK signaling suppresses ERK activation and cell proliferation in drug-resistant cells. Our findings provide non-genetic mechanistic insights into the role of heterogeneity in RTK activation kinetics in ERK reactivation and BRAFi/MEKi resistance, suggesting potential strategies for overcoming drug resistance in BRAF-mutant melanoma.

Sustained release hydrogel for durable locoregional chemoimmunotherapy for BRAF-mutated melanoma

The wide prevalence of BRAF mutations in diagnosed melanomas drove the clinical advancement of BRAF inhibitors in combination with immune checkpoint blockade for treatment of advanced disease. However, deficits in therapeutic potencies and safety profiles motivate the development of more effective strategies that improve the combination therapy's therapeutic index. Herein, we demonstrate the benefits of a locoregional chemoimmunotherapy delivery system, a novel thermosensitive hydrogel comprised of gelatin and Pluronic® F127 components already widely used in humans in both commercial and clinical products, for the co-delivery of a small molecule BRAF inhibitor with immune checkpoint blockade antibody for the treatment of BRAF-mutated melanoma. In vivo evaluation of administration route and immune checkpoint target effects revealed intratumoral administration of antagonistic programmed cell death protein 1 antibody (aPD-1) lead to potent antitumor therapy in combination with BRAF inhibitor vemurafenib. The thermosensitive F127-g-Gelatin hydrogel that was evaluated in multiple murine models of BRAF-mutated melanoma that facilitated prolonged local drug release within the tumor (>1 week) substantially improved local immunomodulation, tumor control, rates of tumor response, and animal survival. Thermosensitive F127-g-Gelatin hydrogels thus improve upon the clinical benefits of vemurafenib and aPD-1 in a locoregional chemoimmunotherapy approach for the treatment of BRAF-mutated melanoma.

Chemical Factory-Guaranteed Enhanced Chemodynamic Therapy for Orthotopic Liver Cancer

In the field of nanomedicine, there is a tendency of matching designed nanomaterials with a suitable type of orthotopic cancer model, not just a casual subcutaneous one. Under this condition, knowing the specific features of the chosen cancer model is the priority, then introducing a proper therapy strategy using designed nanomaterials. Here, the Fenton chemistry is combined with zinc peroxide nanoparticles in the treatment of orthotopic liver cancer which has a "chemical factory" including that liver is the main place for iron storage, metabolism, and also the main metabolic sites for the majority of ingested substances, guaranteeing customized and enhanced chemodynamic therapy and normal liver cells protection as well. The good results in vitro and in vivo can set an inspiring example for exploring and utilizing suitable nanomaterials in corresponding cancer models, ensuring well-fitness of nanomaterials for disease and satisfactory therapeutic effect.

BAMM (BRAF Autophagy and MEK Inhibition in Melanoma): A Phase I/II Trial of Dabrafenib, Trametinib, and Hydroxychloroquine in Advanced BRAFV600-mutant Melanoma

PURPOSE

Autophagy is a resistance mechanism to BRAF/MEK inhibition in BRAFV600-mutant melanoma. Here we used hydroxychloroquine (HCQ) to inhibit autophagy in combination with dabrafenib 150 mg twice daily and trametinib 2 mg every day (D+T).

PATIENTS AND METHODS

We conducted a phase I/II clinical trial in four centers of HCQ + D+T in patients with advanced BRAFV600-mutant melanoma. The primary objectives were the recommended phase II dose (RP2D) and the one-year progression-free survival (PFS) rate of >53%.

RESULTS

Thirty-four patients were evaluable for one-year PFS rate. Patient demographics were as follows: elevated lactate dehydrogenase: 47%; stage IV M1c/M1d: 52%; prior immunotherapy: 50%. In phase I, there was no dose-limiting toxicity. HCQ 600 mg orally twice daily with D+T was the RP2D. The one-year PFS rate was 48.2% [95% confidence interval (CI), 31.0%-65.5%], median PFS was 11.2 months (95% CI, 5.4-16.9 months), and response rate (RR) was 85% (95% CI, 64%-95%). The complete RR was 41% and median overall survival (OS) was 26.5 months. In a patient with elevated LDH (n = 16), the RR was 88% and median PFS and OS were 7.3 and 22 months, respectively.

CONCLUSIONS

HCQ + D+T was well tolerated and produced a high RR but did not meet criteria for success for the one-year PFS rate. There was a high proportion of patients with pretreated and elevated LDH, an increasingly common demographic in patients receiving targeted therapy. In this difficult-to-treat population, the RR and PFS were encouraging. A randomized trial of D+T + HCQ or placebo in patients with BRAFV600-mutant melanoma with elevated LDH and previous immunotherapy is being conducted.

BRAF inhibitors and their immunological effects in malignant melanoma

INTRODUCTION

The treatment of cutaneous melanoma has been revolutionised by the development of small molecule inhibitors targeting the MAPK pathway, including inhibitors of BRAF (BRAFi) and MEK (MEKi), and immune checkpoint blockade antibodies, occurring in tandem. Despite these advances, the 5-year survival rate for patients with advanced melanoma remains only around 50%. Although not designed to alter immune responses within the tumour microenvironment (TME), MAPK pathway inhibitors (MAPKi) exert a range of effects on the host immune compartment which may offer opportunities for therapeutic interventions.

AREAS COVERED

We review the effects of MAPKi especially BRAFi, on the TME, focussing on alterations in inflammatory cytokine secretion, the recruitment of immune cells and their functions, both during response to BRAFi treatment and as resistance develops. We outline potential combinations of MAPKi with established and experimental treatments.

EXPERT OPINION

MAPKi in combination or in sequence with established treatments such as checkpoint inhibitors, anti-angiogenic agents, or new therapies such as adoptive cell therapies, may augment their immunological effects, reverse tumour-associated immune suppression and offer the prospect of longer-lived clinical responses. Refining therapeutic tools at our disposal and embracing "old friends" in the melanoma treatment arsenal, alongside new target identification, may improve the chances of therapeutic success.

The evolution of acquired resistance to BRAF inhibitor is sustained by IGF1-driven tumor vascular remodeling

As hallmark of cancer, angiogenesis plays a pivotal role in carcinogenesis. The correlation between angiogenesis and evolution of BRAF inhibitor acquired resistance is, however, still poorly understood. Here, we reported that the molecular signatures of angiogenesis were enriched in early on-treated biopsies but not in disease progressed biopsies. The process of drug resistance development was accompanied by remodeling of vascular morphology, which was potentially manipulated by tumor-secreted pro-angiogenic factors. Further transcriptomic dissection indicated that tumor-secreted IGF1 drove the vascular remodeling through activating IGF1/IGF1R axis on endothelial cells, and sustained the prompt re-growth of resistant tumor. Blockade of IGF1R with small molecules at early stage of response disrupted vascular reconstruction, and subsequently delayed tumor relapse. Our findings not only demonstrated the correlation between IGF1-mediated tumor vascular remodeling and the development of acquired resistance to BRAFi but also provided a potential therapeutic strategy for the prevention of tumor relapse in clinical application.

Using proteomic and transcriptomic data to assess activation of intracellular molecular pathways

Analysis of molecular pathway activation is the recent instrument that helps to quantize activities of various intracellular signaling, structural, DNA synthesis and repair, and biochemical processes. This may have a deep impact in fundamental research, bioindustry, and medicine. Unlike gene ontology analyses and numerous qualitative methods that can establish whether a pathway is affected in principle, the quantitative approach has the advantage of exactly measuring the extent of a pathway up/downregulation. This results in emergence of a new generation of molecular biomarkers-pathway activation levels, which reflect concentration changes of all measurable pathway components. The input data can be the high-throughput proteomic or transcriptomic profiles, and the output numbers take both positive and negative values and positively reflect overall pathway activation. Due to their nature, the pathway activation levels are more robust biomarkers compared to the individual gene products/protein levels. Here, we review the current knowledge of the quantitative gene expression interrogation methods and their applications for the molecular pathway quantization. We consider enclosed bioinformatic algorithms and their applications for solving real-world problems. Besides a plethora of applications in basic life sciences, the quantitative pathway analysis can improve molecular design and clinical investigations in pharmaceutical industry, can help finding new active biotechnological components and can significantly contribute to the progressive evolution of personalized medicine. In addition to the theoretical principles and concepts, we also propose publicly available software for the use of large-scale protein/RNA expression data to assess the human pathway activation levels.

Design and synthesis of 4-anilinoquinazolines as Raf kinase inhibitors. Part 1. Selective B-Raf/B-RafV600E and potent EGFR/VEGFR2 inhibitory 4-(3-hydroxyanilino)-6-(1H-1,2,3-triazol-4-yl)quinazolines

This paper presents the design and synthesis of 4-(3-hydroxyanilino)-6-(1H-1,2,3-triazol-4-yl)quinazolines of scaffold 9 as selective B-Raf/B-Raf^V600E and potent EGFR/VEGFR2 kinase inhibitors. Total 14 compounds of scaffold 9 having different side chains at the triazolyl group with/without fluoro substituents at the anilino group were synthesized and investigated. Among them, 9m with a 2-carbamoylethyl side chain and C-4'/C-6' difluoro substituents was the most potent, which selectively inhibited B-Raf (IC₅₀: 57 nM) and B-Raf^V600E (IC₅₀: 51 nM) over C-Raf (IC₅₀: 1.0 μM). Compound 9m also actively inhibited EGFR (IC₅₀: 73 nM) and VEGFR2 (IC₅₀: 7.0 nM) but not EGFR^T790M and PDGFR-β (IC₅₀: >10 μM). Despite having good potency for B-Raf and B-Raf^V600E in the enzymatic assays, 9m was less active to inhibit melanoma A375 cells which proliferate due to constitutively activated B-Raf^600E. The inferior activity of 9m for A375 was similar to that of sorafenib (6), suggesting that 9m might bind to the inactive conformations of B-Raf and B-Raf^V600E. Docking simulations could thus be performed to reveal the binding poses of 9m in B-Raf, B-Raf^V600E, and VEGFR2 kinases.

A regularized functional regression model enabling transcriptome-wide dosage-dependent association study of cancer drug response

Cancer treatments can be highly toxic and frequently only a subset of the patient population will benefit from a given treatment. Tumour genetic makeup plays an important role in cancer drug sensitivity. We suspect that gene expression markers could be used as a decision aid for treatment selection or dosage tuning. Using in vitro cancer cell line dose-response and gene expression data from the Genomics of Drug Sensitivity in Cancer (GDSC) project, we build a dose-varying regression model. Unlike existing approaches, this allows us to estimate dosage-dependent associations with gene expression. We include the transcriptomic profiles as dose-invariant covariates into the regression model and assume that their effect varies smoothly over the dosage levels. A two-stage variable selection algorithm (variable screening followed by penalized regression) is used to identify genetic factors that are associated with drug response over the varying dosages. We evaluate the effectiveness of our method using simulation studies focusing on the choice of tuning parameters and cross-validation for predictive accuracy assessment. We further apply the model to data from five BRAF targeted compounds applied to different cancer cell lines under different dosage levels. We highlight the dosage-dependent dynamics of the associations between the selected genes and drug response, and we perform pathway enrichment analysis to show that the selected genes play an important role in pathways related to tumorigenesis and DNA damage response.

Reevaluation of metanephric stromal tumor two decades after it was named: A narrative review

OBJECTIVE

The aim of this narrative review is to provide an overview and update of metanephric stromal tumor (MST).

MATERIALS AND METHODS

All English language studies published from January 1, 2000 to December 31, 2019 in PubMed, EBSCO, Elsevier ScienceDirect, Springer Link and Taylor & Francis databases were searched with the search terms "metanephric stromal tumor" for this review.

RESULTS

Seventeen eligible case reports representing 47 patients according to inclusion and exclusion criteria were included in this study. The average age of the patients was under 4 years (range from 2 d to 56 y) and over half of the cases (52.1%, 25/47) are were diagnosed as MST by accident or during examinations for other diseases. Morphologically, tumor specimens of almost all cases presented concentric "onion-skin cuffing" or characteristic collarettes around renal tubules under low power. There were 79.2% (18/25) of patients exhibited BRAF V600E mutations. Immunohistochemistry (IHC) is characterized by CD34 (+), Vimentin (+), Desmin (-), S-100 (-), SMA (-). Most patients underwent surgeries, and no metastasis or recurrence was found except for one case.

CONCLUSION

MST is a rare benign pediatric renal tumor with surgical treatment as the first choice. CT examinations and ultrasonography are two widely accepted techniques for the diagnosis of MST. Percutaneous renal biopsy (PRB) is an effective and accurate way of preoperative diagnosis, however, it is not recommended for children under 10 years or with a cystic mass in CT images. The relationship between BRAF V600E mutations and mild clinical manifestations of MST is in need of further verification by biological experiments and clinical studies.

Differential association of CD68+ and CD163+ macrophages with macrophage enzymes, whole tumour gene expression and overall survival in advanced melanoma

Background

The density and phenotype of tumour-associated macrophages have been linked with prognosis in a range of solid tumours. While there is strong preclinical evidence that tumour-associated macrophages promote aspects of tumour progression, it can be challenging to infer clinical activity from surface markers and ex vivo behaviour. We investigated the association of macrophage infiltration with prognosis and functional changes in the tumour microenvironment in primary human melanoma.

Methods

Fifty-seven formalin-fixed, paraffin-embedded primary melanomas were analysed by immunohistochemical analysis of CD68, CD163, inducible nitric oxide synthase (iNOS) and arginase expression. RNA sequencing was performed on serial sections of 20 of the stained tumours to determine the influence of macrophage infiltration on gene expression.

Results

CD68⁺ cells are a functionally active subset of macrophages that are associated with increased iNOS and arginase staining and altered gene expression. In comparison, while there is a greater accumulation of CD163⁺ macrophages in larger tumours, these cells are comparatively inactive, with no association with the level of iNOS or arginase staining, and no effect on gene expression within the tumour. The infiltration of either subset of macrophages did not correlate to overall survival.

Conclusions

Thus, melanomas contain distinct macrophage populations with diverse phenotypes, but with no observable prognostic role.

A Driver Never Works Alone-Interplay Networks of Mutant p53, MYC, RAS, and Other Universal Oncogenic Drivers in Human Cancer

The knowledge accumulating on the occurrence and mechanisms of the activation of oncogenes in human neoplasia necessitates an increasingly detailed understanding of their systemic interactions. None of the known oncogenic drivers work in isolation from the other oncogenic pathways. The cooperation between these pathways is an indispensable element of a multistep carcinogenesis, which apart from inactivation of tumor suppressors, always includes the activation of two or more proto-oncogenes. In this review we focus on representative examples of the interaction of major oncogenic drivers with one another. The drivers are selected according to the following criteria: (1) the highest frequency of known activation in human neoplasia (by mutations or otherwise), (2) activation in a wide range of neoplasia types (universality) and (3) as a part of a distinguishable pathway, (4) being a known cause of phenotypic addiction of neoplastic cells and thus a promising therapeutic target. Each of these universal oncogenic factors—mutant p53, KRAS and CMYC proteins, telomerase ribonucleoprotein, proteasome machinery, HSP molecular chaperones, NF-κB and WNT pathways, AP-1 and YAP/TAZ transcription factors and non-coding RNAs—has a vast network of molecular interrelations and common partners. Understanding this network allows for the hunt for novel therapeutic targets and protocols to counteract drug resistance in a clinical neoplasia treatment.

Dual Inhibition of MAPK and JAK2/STAT3 Pathways Is Critical for the Treatment of BRAF Mutant Melanoma

BRAF and MEK inhibitors significantly prolong progression-free survival in patients with BRAF mutant melanoma. However, most patients quickly develop drug resistance. The mechanism of drug resistance is complicated and remains to be further explored. Here, we found that inhibition of the MAPK pathway activates the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway, whereas JAK2 inhibitors that inhibit the JAK2/STAT3 pathway activate the MAPK pathway, suggesting a crosstalk between these two pathways in BRAF mutant melanoma cells. Reactivation of the MAPK pathway occurs in most drug-resistant patients with BRAF mutations. Therefore, dual inhibition of the MAPK and JAK2/STAT3 pathways is critical for the treatment of BRAF mutant melanoma. However, we found that the combination of BRAF, MEK inhibitors, and JAK2 or STAT3 inhibitors could not simultaneously inhibit the MAPK and JAK2/STAT3 pathways in BRAF mutant melanoma cells. Subsequently, we found that a combination of all three MAPK pathway inhibitors—BRAF, MEK, and ERK inhibitors—with JAK2 or STAT3 inhibitors can dually inhibit the MAPK and JAK2/STAT3 pathways, showing a significant inhibition of the growth of BRAF mutant melanoma cells compared with either treatment alone. Therefore, dual inhibition of MAPK and JAK2/STAT3 pathways may be a novel strategy for the treatment of BRAF mutant tumors.

Effect and Molecular Mechanisms of Traditional Chinese Medicine on Tumor Targeting Tumor-Associated Macrophages

Traditional Chinese medicine (TCM) has been used as a significant cancer treatment method for many years in China. It has been demonstrated that TCM could assist in inhibiting the growth of tumors and prolonging the survival rates of cancer patients. Although the mechanism of TCM are still not clear, accumulating evidence has shown that they may be related to the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) play a significant role in TME and are polarized to two phenotypes, M1 (classically activated) and M2 (alternatively activated) TAMs. The two different phenotypes of TAMs play converse roles in the TME and M2-polarized tumor-associated macrophages (M2-TAMs) always lead to poor prognosis in cancer patients compared to M1-polarized tumor-associated macrophages (M1-TAMs). In this review, the potential correlation between TCM and TAMs (especially the M2 phenotype) in tumor progression and promising TCM strategies targeting TAMs in cancer are discussed.

Localized controlled release of bevacizumab and doxorubicin by thermo-sensitive hydrogel for normalization of tumor vasculature and to enhance the efficacy of chemotherapy

In a malignant tumor, overexpression of pro-angiogenic factors like vascular endothelial growth factor (VEGF) provokes the production of pathologic vascular networks characterized by leaky, chaotically organized, immature, thin-walled, and ill-perfused. As a result, hostile tumor environment would be developed and profoundly hinders anti-cancer drug activities and fuels tumor progression. In this study, we develop a strategy of sequential sustain release of anti-angiogenic drug, Bevacizumab (BVZ), and anti-cancer drug, Doxorubicin (DOX), using poly (d, l-Lactide)- Poly (ethylene glycol) -Poly (d, l-Lactide) (PDLLA-PEG-PDLLA) hydrogel as a local delivery system. The release profiles of the drugs from the hydrogel were investigated in vitro which confirmed that relatively rapid release of BVZ (73.56 ± 1.39%) followed by Dox (61.21 ± 0.62%) at pH 6.5 for prolonged period. The in vitro cytotoxicity test revealed that the copolymer exhibited negligible cytotoxicity up to 2.5 mg ml^-1 concentration on HaCaT and HeLa cells. Likeways, the in vitro degradation of the copolymer showed 41.63 ± 2.62% and 73.25 ± 4.36% weight loss within 6 weeks at pH 7.4 and 6.5, respectively. After a single intratumoral injection of the drug-encapsulated hydrogel on Hela xenograft nude, hydrogel co-loaded with BVZ and Dox displayed the highest tumor suppression efficacy for up to 36 days with no noticeable damage on vital organs. Therefore, localized co-delivery of anti-angiogenic drug and anti-cancer drug by hydrogel system may be a promising approach for enhanced chemotherapeutic efficacy in cancer treatment.

RNA sequencing for research and diagnostics in clinical oncology

Molecular diagnostics is becoming one of the major drivers of personalized oncology. With hundreds of different approved anticancer drugs and regimens of their administration, selecting the proper treatment for a patient is at least nontrivial task. This is especially sound for the cases of recurrent and metastatic cancers where the standard lines of therapy failed. Recent trials demonstrated that mutation assays have a strong limitation in personalized selection of therapeutics, consequently, most of the drugs cannot be ranked and only a small percentage of patients can benefit from the screening. Other approaches are, therefore, needed to address a problem of finding proper targeted therapies. The analysis of RNA expression (transcriptomic) profiles presents a reasonable solution because transcriptomics stands a few steps closer to tumor phenotype than the genome analysis. Several recent studies pioneered using transcriptomics for practical oncology and showed truly encouraging clinical results. The possibility of directly measuring of expression levels of molecular drugs' targets and profiling activation of the relevant molecular pathways enables personalized prioritizing for all types of molecular-targeted therapies. RNA sequencing is the most robust tool for the high throughput quantitative transcriptomics. Its use, potentials, and limitations for the clinical oncology will be reviewed here along with the technical aspects such as optimal types of biosamples, RNA sequencing profile normalization, quality controls and several levels of data analysis.

miR-126-3p down-regulation contributes to dabrafenib acquired resistance in melanoma by up-regulating ADAM9 and VEGF-A

Background

Development of resistance to inhibitors of BRAF (BRAFi) and MEK (MEKi) remains a great challenge for targeted therapy in patients with BRAF-mutant melanoma. Here, we explored the role of miRNAs in melanoma acquired resistance to BRAFi.

Methods

miRNA expression in two BRAF-mutant melanoma cell lines and their dabrafenib-resistant sublines was determined using Affymetrix GeneChip® miRNA 3.1 microarrays and/or qRT-PCR. The effects of miR-126-3p re-expression on proliferation, apoptosis, cell cycle, ERK1/2 and AKT phosphorylation, dabrafenib sensitivity, invasiveness and VEGF-A secretion were evaluated in the dabrafenib-resistant sublines using MTT assays, flow cytometry, immunoblotting, invasion assays in Boyden chambers and ELISA. ADAM9, PIK3R2, MMP7 and CXCR4 expression in the sensitive and dabrafenib-resistant cells was determined by immunoblotting. Small RNA interference was performed to investigate the consequence of VEGFA or ADAM9 silencing on proliferation, invasiveness or dabrafenib sensitivity of the resistant sublines. Long-term proliferation assays were carried out in dabrafenib-sensitive cells to assess the effects of enforced miR-126-3p expression or ADAM9 silencing on resistance development. VEGF-A serum levels in melanoma patients treated with BRAFi or BRAFi+MEKi were evaluated at baseline (T0), after two months of treatment (T2) and at progression (TP) by ELISA.

Results

miR-126-3p was significantly down-regulated in the dabrafenib-resistant sublines as compared with their parental counterparts. miR-126-3p replacement in the drug-resistant cells inhibited proliferation, cell cycle progression, phosphorylation of ERK1/2 and/or AKT, invasiveness, VEGF-A and ADAM9 expression, and increased dabrafenib sensitivity. VEGFA or ADAM9 silencing impaired proliferation and invasiveness of the drug-resistant sublines. ADAM9 knock-down in the resistant cells increased dabrafenib sensitivity, whereas miR-126-3p enforced expression or ADAM9 silencing in the drug-sensitive cells delayed the development of resistance. At T0 and T2, statistically significant differences were observed in VEGF-A serum levels between patients who responded to therapy and patients who did not. In responder patients, a significant increase of VEGF-A levels was observed at TP versus T2.

Conclusions

Strategies restoring miR-126-3p expression or targeting VEGF-A or ADAM9 could restrain growth and metastasis of dabrafenib-resistant melanomas and increase their drug sensitivity. Circulating VEGF-A is a promising biomarker for predicting patients’ response to BRAFi or BRAFi+MEKi and for monitoring the onset of resistance.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1238-4) contains supplementary material, which is available to authorized users.

Reprogramming miRNAs global expression orchestrates development of drug resistance in BRAF mutated melanoma

Drug resistance imposes severe limitations to the efficacy of targeted therapy in BRAF-mutated metastatic melanoma. Although this issue has been mitigated by the development of combination therapies with BRAF plus MEK inhibitors, drug resistance inevitably occurs with time and results in clinical recurrences and untreatable disease. Hence, there is strong need of developing new combination therapies and non-invasive diagnostics for the early identification of drug-resistant patients. We report here that the development of drug resistance to BRAFi is dominated by a dynamic deregulation of a large population of miRNAs, leading to the alteration of cell intrinsic proliferation and survival pathways, as well as of proinflammatory and proangiogenic cues, where a prominent role is played by the miR-199b-5p/VEGF axis. Significant alterations of miRNA expression levels are detectable in tumor biopsies and plasma from patients after disease recurrence. Targeting these alterations blunts the development of drug resistance.

[Research Progress of Targeted Therapy for BRAF Mutation in Advanced Non-small Cell Lung Cancer]

靶向治疗是驱动基因阳性晚期非小细胞肺癌（non-small cell lung cancer, NSCLC）的重要治疗手段之一。鼠类肉瘤病毒癌基因同源物B1（v-raf murine sar-coma viral oncogene homolog B1, BRAF）基因是继表皮生长因子受体（epidermal growth factor receptor, EGFR）基因突变、间变性淋巴瘤激酶（anaplastic lymphoma kinase, ALK）基因融合和ROS1基因重排之后，NSCLC又一个重要的驱动基因。BRAF V600E突变占BRAF基因突变的一半以上，是晚期NSCLC的潜在治疗靶点，本文主要对BRAF基因突变类型及相关靶向研究进展进行综述。。

Linking drug target and pathway activation for effective therapy using multi-task learning

Despite the abundance of large-scale molecular and drug-response data, the insights gained about the mechanisms underlying treatment efficacy in cancer has been in general limited. Machine learning algorithms applied to those datasets most often are used to provide predictions without interpretation, or reveal single drug-gene association and fail to derive robust insights. We propose to use Macau, a bayesian multitask multi-relational algorithm to generalize from individual drugs and genes and explore the interactions between the drug targets and signaling pathways' activation. A typical insight would be: "Activation of pathway Y will confer sensitivity to any drug targeting protein X". We applied our methodology to the Genomics of Drug Sensitivity in Cancer (GDSC) screening, using gene expression of 990 cancer cell lines, activity scores of 11 signaling pathways derived from the tool PROGENy as cell line input and 228 nominal targets for 265 drugs as drug input. These interactions can guide a tissue-specific combination treatment strategy, for example suggesting to modulate a certain pathway to maximize the drug response for a given tissue. We confirmed in literature drug combination strategies derived from our result for brain, skin and stomach tissues. Such an analysis of interactions across tissues might help target discovery, drug repurposing and patient stratification strategies.

Modulation the crosstalk between tumor-associated macrophages and non-small cell lung cancer to inhibit tumor migration and invasion by ginsenoside Rh2

Background

Tumor-associated macrophages (TAMs) play a critical role in modulating the tumor microenvironment and promote tumor metastases. Our studies have demonstrated that ginsenoside Rh2 (G-Rh2), a monomeric compound extracted from ginseng, is a promising anti-tumor agent in lung cancer cells. However, it remains unclear whetherG-Rh2 can modulate the differentiation of TAMs and its interaction with tumor microenvironment. In this study, we investigated how G-Rh2 regulates the phenotype of macrophages and affects the migration of non-small cell lung cancer (NSCLC) cells.

Methods

Murine macrophage-like RAW264.7 cells and human THP-1 monocyte were differentiated into M1 and M2 subsets of macrophages with different cytokines combination, which were further identified by flow cytometry with specific biomarkers. M2 macrophages were sorted out to co-culture with NSCLC cell lines, A549 and H1299. Wound healing assay was performed to examine the cell migration. Expression levels of matrix metalloproteinases 2 and 9 (MMP-2, − 9) and vascular endothelial growth factor-C (VEGF-C) were measured by RT-qPCR and western blot, and the release of VEGF in the supernatant was measured by a VEGF ELISA kit. Finally, modulation of TAMs phenotype and VEGF expression by G-Rh2 was examined in vivo.

Results

We demonstrated that M2 subset of macrophages alternatively differentiated from RAW264.7 or THP-1cells promote migration of NSCLC cells. Further examinations revealed that NSCLC significantly increased the release of VEGF to the media and elevated the expression levels of VEGF at mRNA and protein levels after being co-cultured with M2 macrophages. Similar alterations in MMP-2 and MMP-9 were observed in NSCLC after being co-cultured. Of note,G-Rh2 had a potential to effectively convert M2 phenotype to M1 subset of macrophages. Importantly, G-Rh2 had a preference to decrease the expression levels of VEGF, MMP2, and MMP9 in co-cultured lung cancer cells, over than those in lung cancer cells without co-culturing. Consistently, G-Rh2 reduced M2 macrophage marker CD206 and VEGF expression levels in vivo.

Conclusions

All of these results suggested that M2 subset macrophages drive lung cancer cells with more aggressive phenotypes. G-Rh2 has a potential to convert TAMs from M2 subset to M1 in the microenvironment and prevents lung cancer cell migration, suggesting the therapeutic effects of G-Rh2onlung cancer.

Therapy for Cancer: Strategy of Combining Anti-Angiogenic and Target Therapies

The concept that blood supply is required and necessary for cancer growth and spreading is intuitive and was firstly formalized by Judah Folkman in 1971, when he demonstrated that cancer cells release molecules able to promote the proliferation of endothelial cells and the formation of new vessels. This seminal result has initiated one of the most fascinating story of the medicine, which is offering a window of opportunity for cancer treatment based on the use of molecules inhibiting tumor angiogenesis and in particular vascular-endothelial growth factor (VEGF), which is the master gene in vasculature formation and is the commonest target of anti-angiogenic regimens. However, the clinical results are far from the remarkable successes obtained in pre-clinical models. The reasons of this discrepancy have been partially understood and well addressed in many reviews (Bergers and Hanahan, 2008; Bottsford-Miller et al., 2012; El-Kenawi and El-Remessy, 2013; Wang et al., 2015; Jayson et al., 2016). At present anti-angiogenic regimens are not used as single treatments but associated with standard chemotherapies. Based on emerging knowledge of the biology of VEGF, here we sustain the hypothesis of the efficacy of a dual approach based on targeting pro-angiogenic pathways and other druggable targets such as mutated oncogenes or the immune system.

VEGF blockade enhances the antitumor effect of BRAFV600E inhibition

The development of resistance remains a major obstacle to long‐term disease control in cancer patients treated with targeted therapies. In BRAF‐mutant mouse models, we demonstrate that although targeted inhibition of either BRAF or VEGF initially suppresses the growth of BRAF‐mutant tumors, combined inhibition of both pathways results in apoptosis, long‐lasting tumor responses, reduction in lung colonization, and delayed onset of acquired resistance to the BRAF inhibitor PLX4720. As well as inducing tumor vascular normalization and ameliorating hypoxia, this approach induces remodeling of the extracellular matrix, infiltration of macrophages with an M1‐like phenotype, and reduction in cancer‐associated fibroblasts. At the molecular level, this therapeutic regimen results in a de novo transcriptional signature, which sustains and explains the observed efficacy with regard to cancer progression. Collectively, our findings offer new biological rationales for the management of clinical resistance to BRAF inhibitors based on the combination between BRAF^V600E inhibitors with anti‐angiogenic regimens.