The molecular biology of lung cancer brain metastasis: an overview of current comprehensions and future perspectives

Brain metastases and lung cancer: molecular biology, natural history, prediction of response and efficacy of immunotherapy

Brain metastases stemming from lung cancer represent a common and challenging complication that significantly impacts patients' overall health. The migration of these cancerous cells from lung lesions to the central nervous system is facilitated by diverse molecular changes and a specific environment that supports their affinity for neural tissues. The advent of immunotherapy and its varied combinations in non-small cell lung cancer has notably improved patient survival rates, even in cases involving brain metastases. These therapies exhibit enhanced penetration into the central nervous system compared to traditional chemotherapy. This review outlines the molecular mechanisms underlying the development of brain metastases in lung cancer and explores the efficacy of novel immunotherapy approaches and their combinations.

Efficacy of PP121 in primary and metastatic non‑small cell lung cancers

Tyrosine kinase inhibitors are a clinically standard treatment option for non-small cell lung cancers (NSCLCs), the leading cause of cancer-related deaths in the US. These targeted agents include first, second and third generation tyrosine kinase inhibitors; however, these lack clinical efficacy in the treatment of NSCLC due to intrinsic and acquired resistance. This resistance may be a result of genetic aberrations in oncogenic signaling mediators of divergent pathways. The present study aimed to investigate a novel dual tyrosine kinase and PI3K inhibitor, PP121, as a targeted agent in NSCLC cell lines. The present study co-cultured PP121 with healthy human astrocytes, a prevalent cell type located in the brain of NSCLC brain metastases. To date, few preclinical studies have examined the efficacy of PP121 as an anticancer agent, and to the best of my knowledge, no previous studies have previously evaluated its therapeutic potential in the treatment of NSCLC. To investigate the clinical heterogeneity of NSCLC, patient-derived adenocarcinoma (ADC) and squamous cell carcinoma (SCC) xenograft models were used, which exhibited epidermal growth factor receptor (EGFR) mutations and mesenchymal-epithelial transition (MET) factor amplifications. Notably, both EGFR and MET are known contributors to tyrosine kinase inhibitor resistance; thus, the aforementioned mutations and amplifications enabled the effects of PP121 to be evaluated in these solid tumors. In addition, a co-cultured model system using both NSCLC cells and astrocytes was employed to assess the effects of PP121 on the invasion of ADC and SCC cells in a multicellular environment. Results of the present study demonstrated that PP121 exerted an antitumorigenic effect in the aforementioned model systems via downregulation of pharmacodynamic targets.

The Journey of Cancer Cells to the Brain: Challenges and Opportunities

Cancer metastases into the brain constitute one of the most severe, but not uncommon, manifestations of cancer progression. Several factors control how cancer cells interact with the brain to establish metastasis. These factors include mediators of signaling pathways participating in migration, infiltration of the blood-brain barrier, interaction with host cells (e.g., neurons, astrocytes), and the immune system. Development of novel therapies offers a glimpse of hope for increasing the diminutive life expectancy currently forecasted for patients suffering from brain metastasis. However, applying these treatment strategies has not been sufficiently effective. Therefore, there is a need for a better understanding of the metastasis process to uncover novel therapeutic targets. In this review, we follow the journey of various cancer cells from their primary location through the diverse processes that they undergo to colonize the brain. These processes include EMT, intravasation, extravasation, and infiltration of the blood-brain barrier, ending up with colonization and angiogenesis. In each phase, we focus on the pathways engaging molecules that potentially could be drug target candidates.

WDR5 is a prognostic biomarker of brain metastasis from non-small cell lung cancer

Background

Lung cancer (LC) is the most frequent caner type and causes the most cancer-related death. Brain metastases (BM) are the deadliest complications of lung cancer, and the prognostic biomarkers of BM are urgently needed.

Materials and methods

In our study, we established an inception cohort including 122 patients with asynchronous BM from NSCLC, and further selected 70 patients who received surgical resection, which compromised the validation cohort. With immunohistochemistry, we investigated the expression of WDR5 in the cohort. By chi-square method, the correlations between WDR5 and clinicopathological factors were analyzed. The prognostic indicators were analyzed with the univariate analysis, and independent prognostic factors were identified by multivariate analysis with Cox-regression model.

Results

WDR5 is frequently expressed in the cytoplasm of BM from NSCLC. Patients with low or high expression of WDR5 account for 60% and 40% respectively. High expression of WDR5 indicates poor prognosis of BM from NSCLC (P=0.001). In addition to WDR5, KPS is also a prognostic factor of BM, and high KPS predicts favorable prognosis (P=0.006). WDR5 is an independent prognostic biomarker for poor prognosis of BM from NSCLC, with the cancer-related odds as 2.48.

Conclusions

High expression of WDR5 can predict the poor prognosis of BM, and WDR5 is an independent prognostic biomarker of BM from NSCLC. Patients with WDR5 overexpression are more high-risk to suffer BM-related death and should receive more intense post-operational supervision.

Central nervous systemic efficacy of immune checkpoint inhibitors and concordance between intra/extracranial response in non-small cell lung cancer patients with brain metastasis

PURPOSE

Immune checkpoint inhibitors (ICIs) markedly improve the clinical outcomes of advanced non-small-cell lung cancer (NSCLC). However, the intracranial efficacy of ICI is not well elucidated, and previous studies showed discordant outcomes of ICI between intracranial and extracranial diseases. We aimed to evaluate the clinical outcomes and the intracranial and extracranial response of patients with NSCLC and brain metastasis who were treated with ICI in the real-world setting.

METHODS

A total of 55 patients (median age, 63 years [range 42-80]; male, 78%) who had NSCLC with brain metastasis and treated with ICI monotherapy were retrospectively analyzed. We separately assessed the response rates of brain lesions and systemic lesions, and estimated the overall survival (OS) and progression-free survival (PFS).

RESULTS

The median OS and overall PFS were 17.0 months (95% CI 10.3-25.6) and 3.19 months (95% CI 2.24-5.03), respectively. The intracranial objective response rate and disease control rate of ICI were 36 and 54%, respectively. Among the 44 patients who showed disease progression, only 32% (n = 14) showed concordant outcomes and 9 patients (20%) showed opposing discordant outcomes. Eight patients continued ICI with local brain therapy after intracranial progression, and their median extracranial PFS and OS were 15 months (95% CI 5.0-not assessed [NA]) and 23.8 months (95% CI 14.7-NA), respectively.

CONCLUSIONS

ICI monotherapy had a clinically meaningful intracranial efficacy in NSCLC patients with brain metastasis. Watchful waiting and close monitoring without local radiotherapy might be feasible in NSCLC patients with asymptomatic active brain metastasis.

The Significance of MicroRNAs in the Molecular Pathology of Brain Metastases

Brain metastases are the most frequent intracranial tumors in adults and the cause of death in almost one-fourth of cases. The incidence of brain metastases is steadily increasing. The main reason for this increase could be the introduction of new and more efficient therapeutic strategies that lead to longer survival but, at the same time, cause a higher risk of brain parenchyma infiltration. In addition, the advances in imaging methodology, which provide earlier identification of brain metastases, may also be a reason for the higher recorded number of patients with these tumors. Metastasis is a complex biological process that is still largely unexplored, influenced by many factors and involving many molecules. A deeper understanding of the process will allow the discovery of more effective diagnostic and therapeutic approaches that could improve the quality and length of patient survival. Recent studies have shown that microRNAs (miRNAs) are essential molecules that are involved in specific steps of the metastatic cascade. MiRNAs are endogenously expressed small non-coding RNAs that act as post-transcriptional regulators of gene expression and thus regulate most cellular processes. The dysregulation of these molecules has been implicated in many cancers, including brain metastases. Therefore, miRNAs represent promising diagnostic molecules and therapeutic targets in brain metastases. This review summarizes the current knowledge on the importance of miRNAs in brain metastasis, focusing on their involvement in the metastatic cascade and their potential clinical implications.

Correlation Analysis between Retention of Gd-DTPA in the Cystic Area of Brain Metastasis and MRI Signs

Objective

The aim of this study is to investigate gadolinium-diethylenetriaminepentacetate (Gd-DTPA) retention in the cystic area of brain metastasis and its correlation with MRI signs.

Methods

Clinical and MRI data of 76 patients with brain metastasis in the cystic area were collected. The contrast signal intensity (CSI) of the cystic area and edema area in the plain scan, enhanced scan, and plain scan after enhancement within 1 month (hereafter referred to as “enhanced plain scan”) were analyzed to determine whether Gd-DTPA was retained in these areas. The lesions with higher CSI values on the enhanced plain scan were classified as the Gd-DTPA retention group and the remaining lesions as the Gd-DTPA-free group. The two groups were compared to determine significant differences in primary lesion type, tumor size, tumor location, capsule wall thickness and morphology, peritumoral edema, and renal function.

Results

A total of 123 lesions were detected. The CSI of the enhanced plain scan exceeded that of the plain scan and enhanced scan in the cystic area (P < 0.05). There were 54 lesions (43.9%) with Gd-DTPA retention in the cystic area and 69 lesions (56.1%) without Gd-DTPA retention. Significant differences were observed in tumor size and cystic wall thickness between the two groups (P < 0.05), while no significant differences in primary lesion type, cystic wall shape, peritumoral edema, or function were observed.

Conclusion

The retention of Gd-DTPA was found in the cystic area of some brain metastases, which was correlated with tumor size and cystic wall thickness.

Prognosis of lung cancer with simple brain metastasis patients and establishment of survival prediction models: a study based on real events

Objectives

The aim of this study was to explore risk factors for the prognosis of lung cancer with simple brain metastasis (LCSBM) patients and to establish a prognostic predictive nomogram for LCSBM patients.

Materials and methods

Three thousand eight hundred and six cases of LCSBM were extracted from the Surveillance, Epidemiology, and End Results (SEER) database from 2010 to 2015 using SEER Stat 8.3.5. Lung cancer patients only had brain metastasis with no other organ metastasis were defined as LCSBM patients. Prognostic factors of LCSBM were analyzed with log-rank method and Cox proportional hazards model. Independent risk and protective prognostic factors were used to construct nomogram with accelerated failure time model. C-index was used to evaluate the prediction effect of nomogram.

Results and conclusion

The younger patients (18–65 years old) accounted for 54.41%, while patients aged over 65 accounted for 45.59%.The ratio of male: female was 1:1. Lung cancer in the main bronchus, upper lobe, middle lobe and lower lobe were accounted for 4.91%, 62.80%, 4.47% and 27.82% respectively; and adenocarcinoma accounted for 57.83% of all lung cancer types. The overall median survival time was 12.2 months. Survival rates for 1-, 3- and 5-years were 28.2%, 8.7% and 4.7% respectively. We found female (HR = 0.81, 95% CI 0.75–0.87), the married (HR = 0.80; 95% CI 0.75–0.86), the White (HR = 0.90, 95% CI 0.84–0.95) and primary site (HR = 0.45, 95% CI 0.39–0.52) were independent protective factors while higher age (HR = 1.51, 95% CI 1.40–1.62), advanced grade (HR = 1.19, 95% CI 1.12–1.25) and advanced T stage (HR = 1.09, 95% CI 1.05–1.13) were independent risk prognostic factors affecting the survival of LCSBM patients. We constructed the nomogram with above independent factors, and the C-index value was 0.634 (95% CI 0.622–0.646). We developed a nomogram with seven significant LCSBM independent prognostic factors to provide prognosis prediction.

Epidermal growth factor receptor-targeted therapy for the treatment of non-small cell lung cancer: A review of phase II and III trials

INTRODUCTION

EGFR is one of the most common driver gene mutations in lung cancer. EGFR-TKI monotherapy and EGFR-TKI combined with chemotherapy or anti-angiogenesis drugs have significantly prolonged the survival of patients with EGFR-mutant NSCLC. However, disease progression caused by acquired resistance to EGFR-TKIs is inevitable. And patients with EGFR exon 20ins showed limited efficacy to EGFR-TKIs.

AREAS COVERED

In this review, we initially evaluated the efficacy of existing treatments for EGFR-mutant NSCLC. Second, we reviewed the ongoing phase II and III clinical trials, provide the latest results, discuss the scientific rationale of these trials and the potential development issues.

EXPERT OPINION

The application of EGFR-TKIs has greatly changed the therapeutic strategies for advanced and resected NSCLC with EGFR mutations, and the 5-year OS rate for advanced NSCLC was close to 40%. The current research direction for the treatment of patients with EGFR mutations focuses on the following three aspects: uncommon EGFR mutation subtypes NSCLC, brain metastases, and EGFR TKI-based combination therapy. Future studies on EGFR-mutant NSCLC therapy will focus on overcoming EGFR-TKI-related resistance, preventing drug resistance in advance, and developing bispecific antibody drugs. ADCs may be the promising strategy for patients with acquired resistance to EGFR-TKIs.

Perifosine, a Bioavailable Alkylphospholipid Akt Inhibitor, Exhibits Antitumor Activity in Murine Models of Cancer Brain Metastasis Through Favorable Tumor Exposure

Metastatic brain tumors are regarded as the most advanced stage of certain types of cancer; however, chemotherapy has played a limited role in the treatment of brain metastases. Here, we established murine models of brain metastasis using cell lines derived from human brain metastatic tumors, and aimed to explore the antitumor efficacy of perifosine, an orally active allosteric Akt inhibitor. We evaluated the effectiveness of perifosine by using it as a single agent in ectopic and orthotopic models created by injecting the DU 145 and NCI-H1915 cell lines into mice. Initially, the injected cells formed distant multifocal lesions in the brains of NCI-H1915 mice, making surgical resection impractical in clinical settings. We determined that perifosine could distribute into the brain and remain localized in that region for a long period. Perifosine significantly prolonged the survival of DU 145 and NCI-H1915 orthotopic brain tumor mice; additionally, complete tumor regression was observed in the NCI-H1915 model. Perifosine also elicited much stronger antitumor responses against subcutaneous NCI-H1915 growth; a similar trend of sensitivity to perifosine was also observed in the orthotopic models. Moreover, the degree of suppression of NCI-H1915 tumor growth was associated with long-term exposure to a high level of perifosine at the tumor site and the resultant blockage of the PI3K/Akt signaling pathway, a decrease in tumor cell proliferation, and increased apoptosis. The results presented here provide a promising approach for the future treatment of patients with metastatic brain cancers and emphasize the importance of enriching a patient population that has a higher probability of responding to perifosine.

The value of DTI: achieving high diagnostic performance for brain metastasis

BACKGROUND

The evaluation of brain metastases generally requires post-contrast MRI exam, but some patients have contraindication to contrast medium administration.

PURPOSE

To investigate the value of the MRI diffusion tensor imaging (DTI) for detection of metastatic brain tumor.

MATERIALS AND METHODS

We retrospectively analyzed the MRI data from 23 patients (13 males and 10 females) with brain metastases. The MRI protocol consisted in T1WI, T2WI, post-contrast 3DT1WI and DTI images (b = 1000) sequences. The brain metastatic lesions were counted in each of these sequences. We compared the advantages and limitations of different sequences in the brain metastases detection. The number of metastatic lesions identified on the contrast-enhanced 3DT1WI image is used as the reference. FA values were measured in the intratumoral, adjacent peritumoral and distant peritumoral edema area (PTEA) of brain metastasis, and the differences were statistically analyzed.

RESULTS

DTI can detect more brain metastatic lesions rather than T1WI and T2WI. The number of brain metastases on DTI is similar to post-contrast 3D T1WI. There is no statistical difference in the FA value change between the adjacent and distant PTEA.

CONCLUSION

The DTI original image can be used as an alternative examination for patients with contraindications to contrast-enhanced MRI. It has high sensitivity to intratumoral hemorrhage, which has advantage to detect brain metastatic lesions as compared with T1WI or T2WI images.

Efficacy and safety of bevacizumab combined with chemotherapy in symptomatic brain metastases from lung adenocarcinoma: a retrospective analysis

Background

Currently, the treatment of symptomatic brain metastases from lung adenocarcinoma has remained difficult. Bevacizumab combined with chemotherapy is one of the standard treatments of lung adenocarcinoma. This study was designed to investigate the efficacy and safety of bevacizumab combined with chemotherapy in symptomatic brain metastases from lung adenocarcinoma that are not suitable for local treatments, and to explore the predictive value of baseline serum vascular endothelial growth factor (VEGF) for the treatment.

Methods

We retrospectively reviewed 14 consecutive patients, between Jan 2015 and Jul 2017, with brain metastases from lung adenocarcinoma who received bevacizumab and chemotherapy to determine efficacy and toxicity. Kaplan-Meier method was used to estimate survival curves, and univariate and multivariate analyses were performed by Cox proportional hazard model. The primary endpoints were objective response rate (ORR) and intracranial ORR (iORR). The secondary endpoints were progression-free survival (PFS), intracranial PFS (iPFS), overall survival (OS) and disease control rate (DCR).

Results

The efficacy of 12 patient was evaluated. Overall ORR was 25% (3/12) and the iORR of brain lesions was 33.3% (4/12). DCR was 75% (9/12). The median OS was 18.3 months, the median PFS was 6.7 months, and the median iPFS was 12 months. After 2 cycles of bevacizumab, 10 patients showed improved symptoms of central nervous system (CNS), and the symptom control rate was 83.3% (10/12). Head MRI showed that edema in the brain was greatly reduced in 6 patients, resulting in the lessened usage of dexamethasone. iPFS was significantly shorter in high VEGF group (3.6 vs. 8.0 m, P=0.02), and multivariate analysis showed a significant correlation between iPFS and serum baseline VEGF level (P=0.023). The most commonly adverse events of bevacizumab included leukopenia [5 (35.7%)], fatigue [3 (21.4%)], thrombocytopenia [3 (21.4%)], anemia [2 (14.3%)], which were mostly degree I and II.

Conclusions

This study showed bevacizumab combined with chemotherapy could effectively control intracranial lesions, relieve symptoms, and improve the quality of life and survival of patients with brain metastases from lung adenocarcinoma. Serum baseline VEGF may be a predictor of efficacy of bevacizumab plus chemotherapy in the treatment of brain metastases from lung adenocarcinoma.

AKR1B10 (Aldo-keto reductase family 1 B10) promotes brain metastasis of lung cancer cells in a multi-organ microfluidic chip model

Brain metastasis (BM) is a leading cause of mortality in patients with non-small cell lung cancer (NSCLC). However, the molecular mechanisms underlying BM of NSCLC remain largely unknown because of the lack of models to accurately investigate such a dynamic and complex process. Here we developed a multi-organ microfluidic chip as a new methodological platform to study BM. The chip consisted of two bionic organ units - an upstream "lung" and a downstream "brain" characterized by a functional "blood-brain barrier (BBB)" structure, allowing real-time visual monitoring of the entire BM process, from the growth of primary tumor to its breaking through the BBB, and finally reaching the brain parenchyma. The chip was verified by lung cancer cell lines with differing metastatic abilities and then applied for the BM research where we first demonstrated that the protein expression of Aldo-keto reductase family 1 B10 (AKR1B10) was significantly elevated in lung cancer BM. Silencing AKR1B10 in brain metastatic tumor cells suppressed their extravasation through the BBB in the in vitro Transwell model, in our ex vivo microfluidic chip, as well as the in vivo model of brain metastasis in nude mice. Moreover, AKR1B10 downregulated the expression of matrix metalloproteinase (MMP)-2 and MMP-9 via MEK/ERK signaling in metastatic lung cancers. These data suggest that our multi-organ microfluidic chip is a practical alternative to study BM pathogenesis, and AKR1B10 is a diagnostic biomarker and a prospective therapeutic target for NSCLC BM. STATEMENT OF SIGNIFICANCE: Brain metastasis (BM) of non-small cell lung cancer (NSCLC) is a complex cascade, and in particular, the process of lung cancer cells penetrating the blood-brain barrier (BBB) is very unique. However, due to the lack of reliable models that can faithfully mimic the dynamic process of BBB breaking, its molecular mechanisms have not well elucidated so far. In addition, although Aldo-keto reductase family 1 B10 (AKR1B10) has been implicated to the tumor development of liver cancer and many other cancers, little is known on its roles in the BM. Here, we established a multi-organ microfluidic bionic chip platform to recapitulate the entire BM process, and applied it to the BM pathology research, especially BBB extravasation. By using the chip and traditional models synergistically, we first demonstrated that AKR1B10 was significantly elevated in lung cancer BM, and defined the value of AKR1B10 as a diagnostic serum biomarker for lung cancer patients suffering from BM. Further, we investigated the role and mechanisms of AKR1B10 in BM that it promotes the extravasation of cancer cells through the BBB.

A Novel mTORC1/2 Inhibitor (MTI-31) Inhibits Tumor Growth, Epithelial-Mesenchymal Transition, Metastases, and Improves Antitumor Immunity in Preclinical Models of Lung Cancer

PURPOSE

We aimed to investigate efficacy and mechanism of MTI-31 (LXI-15029), a novel mTORC1/mTORC2 inhibitor currently in human trial (NCT03125746), in non-small cell lung cancer (NSCLC) models of multiple driver mutations and tyrosine kinase inhibitor (TKI)-resistance.

EXPERIMENTAL DESIGN

Gene depletion, inhibitor treatment, immunological, flow cytometry, cellular, and animal studies were performed to determine in vitro and in vivo efficacy in NSCLC models of driver mutations and elucidate roles by mTOR complexes in regulating migration, epithelial-mesenchymal transition (EMT), metastasis, intracranial tumor growth, and immune-escape.

RESULTS

MTI-31 potently inhibited cell proliferation (IC₅₀ <1 μmol/L) and in vivo tumor growth in multiple NSCLC models of EGFR/T790M, EML4-ALK, c-Met, or KRAS (MED <10 mg/kg). In EGFR-mutant and/or EML4-ALK-driven NSCLC, MTI-31 or disruption of mTORC2 reduced cell migration, hematogenous metastasis to the lung, and abrogated morphological and functional traits of EMT. Disruption of mTORC2 inhibited EGFR/T790M-positive tumor growth in mouse brain and prolonged animal survival correlating a diminished tumor angiogenesis and recruitment of IBA1+ microglia/macrophages in tumor microenvironment. MTI-31 also suppressed programmed death ligand 1 (PD-L1) in EGFR- and ALK-driven NSCLC, mediated in part by mTORC2/AKT/GSK3β-dependent proteasomal degradation. Depletion of mTOR protein or disruption of mTOR complexes profoundly downregulated PD-L1 and alleviated apoptosis in Jurkat T and primary human T cells in a tumor-T cell coculture system.

CONCLUSIONS

Our results highlight mTOR as a multifaceted regulator of tumor growth, metastasis, and immune-escape in EGFR/ALK-mutant and TKI-resistant NSCLC cells. The newly characterized mechanisms mediated by the rapamycin-resistant mTORC2 warrant clinical investigation of mTORC1/mTORC2 inhibitors in patients with lung cancer.

ZWINT is the next potential target for lung cancer therapy

PURPOSE

We aimed to analyze the expression of ZWINT, NUSAP1, DLGAP5, and PRC1 in tumor tissues and adjacent tissues with public data.

METHODS

The expression patterns of four genes were detected in cancer tissues and adjacent tissues by qRT-PCR. The overall survival analysis was used to explore these genes in lung adenocarcinoma and squamous cell carcinoma patients. Knockdown assays were used to select the most suitable gene among these four genes. Cell function assays with the knockdown gene were conducted in A549 and NCL H226 cells. The role of the knockdown gene in lung cancer was dissected in a mice tumor model. Transcriptome sequencing analyses with the knockdown gene were analyzed.

RESULTS

Overexpression of these genes was significantly detected in cancer tissues (P < 0.01). Overall survival revealed that high expression of these genes is closely related with poor prognosis of lung adenocarcinoma patients (P < 0.05). Knockdown of ZWINT reduced proliferation in NCI H226 and A549 cells (P < 0.05). Knockdown also inhibited cell migration, invasion, apoptosis, and colony formation (P < 0.05). ZWINT knockdown reduced tumor volume (P < 0.05). Transcriptome sequencing of ZWINT knockdown-treated A549 and NCI H226 cells indicated that 100 and 426 differentially expressed genes were obtained, respectively. Gene ontology analysis suggested that binding, biological regulation, and multicellular organismal processes were the most enriched. KEGG analysis revealed that TNF, P53, and PI3K signal networks would be the most potential ZWINT-related pathways and were identified by Western blot analysis.

CONCLUSIONS

ZWINT may be a novel target for lung cancer therapy.

Predictive value of microRNA let-7a expression for efficacy and prognosis of radiotherapy in patients with lung cancer brain metastasis: A case-control study

BACKGROUND

As a well-known cancer with high mortality, lung cancer has been implied to be closely associated with brain metastasis. Despite notable advances, effective treatment methods are still in urgent need. This study aims to investigate the value of serum microRNA-let-7a (miR-let-7a) expression in predicting efficacy and prognosis of radiotherapy in patients with lung cancer brain metastasis.

METHODS

To begin with, reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed for better understand of the correlation between miR-let-7a and lung cancer. Afterwards, the relationship between serum miR-let-7a expression and radiotherapy efficacy was analyzed by receiver operating characteristic curve analysis. Following successful transfection, RT-qPCR and Western blot assay were utilized for evaluating the involvement of miR-let-7a in regulation of DICER1 expression in lung cancer cell line. Then, whether miR-let-7a was implicated in proliferation and cell cycle distribution of lung cancer cells were confirmed by cell counting kit-8 assay and flow cytometry respectively.

RESULTS

Initially, it was revealed that serum miR-let-7a expression was decreased in lung cancer. Later, we found that decreased miR-let-7a displayed an unfavorable role in radiotherapy efficacy and overall survival rate of patients with lung cancer brain metastasis. After the successful transfection, the inverse relationship between miR-let-7a and DICER1 expression was uncovered. Meanwhile, biological behaviors of lung cancer cells were presented to be limited after transfection of overexpressed miR-let-7a.

CONCLUSION

Our findings demonstrated that the lower expression of miR-let-7a in patients with lung cancer brain metastasis was closely related to unfavorable efficacy and prognosis of radiotherapy, and it may be an important predictive biomarker by regulation of DICER1.

Toosendanin, a natural product, inhibited TGF-β1-induced epithelial-mesenchymal transition through ERK/Snail pathway

Epithelial-mesenchymal transition (EMT) plays important roles in the metastasis of solid tumors. In this study, the effect of toosendanin (TSN), a natural insecticide extracted from Melia toosendan Sieb et Zucc, on transforming growth factor-β1 (TGF-β1)-induced EMT was investigated. EMT was induced by TGF-β1 in A549 and H1975 lung cancer cells. The morphological alterations were observed with a microscopy. The protein expression and localization of EMT biomarkers were determined by Western blotting and immunofluorescence. The migration, invasion, and adhesion were determined by wound-healing, transwell, and adhesion assays. TGF-β1 treatment induced spindle-shaped alterations of cells, upregulation of N-cadherin, Vimentin, p-ERK1/2, and downregulation of E-cadherin. The abilities of migration, invasion, and adhesion were also enhanced. These effects were significantly reversed by TSN at very low concentration (<10 nM). Furthermore, silence Snail significantly reversed TGF-β1-induced EMT biomarkers. In addition, TGF-β1-induced phosphorylation of ERK1/2 without affecting p38 mitogen-activated protein kinases and Jun N-terminal kinase. PD98059 and U0126, inhibitors of ERK1/2, showed similar inhibitory effect to that of TSN. In summary, TSN significantly inhibited TGF-β1-induced EMT and migration, invasion, and adhesion through ERK/Snail pathway in lung cancer cells. This study provides novel anticancer effects and molecular mechanisms for TSN.

Identifying candidates for gamma knife radiosurgery among elderly patients with brain metastases

We investigated the outcomes of gamma knife radiosurgery (GKRS) for elderly patients (≥ 65 years) with brain metastases, and identified survival-associated factors. We retrospectively analyzed data from 115 patients treated with GKRS for 1-15 brain metastases. The median patient age was 72 years; most primary tumors were pulmonary (n = 83). The mean lesion volume was 2.1 ± 4.8 mL. A mean dose of 19.3 Gy was delivered to the mean 63.9% isodose line. The median overall survival (OS) was 5.3 months (95% confidence interval [CI] 3.5-7.1). During follow-up (median, 5.1 months), 91 patients died of primary cancer progression while 1 died of unknown causes. The 6- and 12-month local control rates were 94.9 and 88.1%, respectively. On multivariate analysis, female sex (p = 0.005, hazard ratio [HR] 0.533, 95% CI 0.343-0.827) and a controlled primary tumor (p < 0.001, HR 0.328, 95% CI 0.180-0.596) were significantly favorable prognostic factors. Of non-small cell lung cancer patients with EGFR mutations, 76.5% were women (p = 0.005). The median OS of EGFR-mutant and EGFR-wildtype patients were 19.1 and 4.7 months, respectively (p = 0.080). Brain metastases < 3 mL showed better local control rates after GKRS (p = 0.005). GKRS produces favorable outcomes in women with brain metastases who are ≥ 65 years and have controlled primary tumors. Such patients are therefore suitable candidates for GKRS.

Lung cancer-associated brain metastasis: Molecular mechanisms and therapeutic options

BACKGROUND

Lung cancer is the most common cause of cancer-related mortality in humans. There are several reasons for this high rate of mortality, including metastasis to several organs, especially the brain. In fact, lung cancer is responsible for approximately 50% of all brain metastases, which are very difficult to manage. Understanding the cellular and molecular mechanisms underlying lung cancer-associated brain metastasis brings up novel therapeutic promises with the hope to ameliorate the severity of the disease. Here, we provide an overview of the molecular mechanisms underlying the pathogenesis of lung cancer dissemination and metastasis to the brain, as well as promising horizons for impeding lung cancer brain metastasis, including the role of cancer stem cells, the blood-brain barrier, interactions of lung cancer cells with the brain microenvironment and lung cancer-driven systemic processes, as well as the role of growth factor/receptor tyrosine kinases, cell adhesion molecules and non-coding RNAs. In addition, we provide an overview of current and novel therapeutic approaches, including radiotherapy, surgery and stereotactic radiosurgery, chemotherapy, as also targeted cancer stem cell and epithelial-mesenchymal transition (EMT)-based therapies, micro-RNA-based therapies and other small molecule or antibody-based therapies. We will also discuss the daunting potential of some combined therapies.

CONCLUSIONS

The identification of molecular mechanisms underlying lung cancer metastasis has opened up new avenues towards their eradication and provides interesting opportunities for future research aimed at the development of novel targeted therapies.

Advantage of High b Value Diffusion-Weighted Imaging for Differentiation of Hemangioblastoma from Brain Metastases in Posterior Fossa

OBJECTIVE

It is sometimes difficult to make a differential diagnosis between brain metastases and hemangioblastomas in the posterior fossa. We assessed whether high b value diffusion-weighted image (DWI) at b = 4000 could differentiate these tumors.

METHODS

We acquired DWI at 3-T magnetic resonance imaging with b = 1000 and b = 4000 seconds/mm² in histologically confirmed 12 patients of hemangioblastoma without von Hippel-Lindau disease and 16 patients with brain metastases originating at the posterior fossa. Apparent diffusion coefficient (ADC) values were measured by manually placing regions of interest on ADC maps at the site of enhanced tumor confirmed on contrast-enhanced T1- weighed image. ADC was expressed as the minimum (ADC_MIN), mean (ADC_MEAN), and maximum (ADC_MAX) values.

RESULTS

All the ADC values of hemangioblastomas were statistically higher than those of metastatic tumor in both b = 1000 and b = 4000 (P < 0.0001 in ADC_MIN, ADC_MEAN, and ADC_MAX; Mann-Whitney U test). With the cutoff value at 0.6 × 10^-3 mm²/second, the positive predictive value of ADC_MIN at b = 4000 was higher than that of ADC_MIN at b = 1000 (100% vs. 89.3%, logistic analysis) to differentiate hemangioblastomas from brain metastases. Moreover, we studied the pathologic subtype of hemangioblastoma and confirmed that ADCs (b = 4000_MIN) of cellular subtype were statistically lower than those of reticular subtype (P = 0.03; Mann-Whitney U test).

CONCLUSIONS

High b value DWI reflects diffusion more accurately than does regular b value. Our results showed that ADC calculation by high b value (b = 4000) DWI at 3-T magnetic resonance imaging is clinically useful for differentiating hemangioblastomas from brain metastases.

Osthole inhibited TGF β-induced epithelial-mesenchymal transition (EMT) by suppressing NF-κB mediated Snail activation in lung cancer A549 cells

Epithelial-mesenchymal transition (EMT), the transdifferentiation of epithelial cells into mesenchymal cells, has been implicated in the metastasis and provides novel strategies for cancer therapy. Osthole (OST), a dominant active constituent of Chinese herb Cnidium monnieri, has been reported to inhibit cancer metastasis while the mechanisms remains unclear. Here, we studied the inhibitory effect and mechanisms of OST on TGF-β1-induced EMT in A549 cells. Cells were treated with TGF-β1 in the absence and presence of OST. The morphological alterations were observed with a microscopy. The protein and mRNA expressions were determined by Western blotting and real-time PCR. The protein localization was detected with immunofluorescence. The adhesion, migration, and invasion were determined by Matrigel, wound-healing, and Transwell assays. TGF-β1 treatment induced spindle-shaped alterations of cells, upregulation of N-cadherin, Vimentin, NF-κB p65, and downregulation of E-cadherin. Dysregulated membrane expression and mRNA expression of E-cadherin and N-cadherin were observed after TGF-β1 treatment. TGF-β1 increased abilities of migration and invasion and triggered the nuclear translocation of NF-κB p65. These alterations were dramatically inhibited by OST. Furthermore, PDTC, a NF-κB inhibitor, showed similar effects. In addition, TGF-β1-induced expression of Snail was significantly inhibited by OST and silenced Snail partially reversed TGF-β1-induced EMT biomarkers without affecting NF-κB p-65. In conclusion, OST inhibited TGF-β1-induced EMT, adhesion, migration, and invasion through inactivation of NF-κB-Snail pathways in A549 cells. This study provides novel molecular mechanisms for the anti-metastatic effect of OST.

EGFR and KRAS Mutations Predict the Incidence and Outcome of Brain Metastases in Non-Small Cell Lung Cancer

Background: Lung cancer is the leading cause of brain metastases (BM). The identification of driver oncogenes and matched targeted therapies has improved outcome in non-small cell lung cancer (NSCLC) patients; however, a better understanding of BM molecular biology is needed to further drive the process in this field. Methods: In this observational study, stage IV NSCLC patients tested for EGFR and KRAS mutations were selected, and BM incidence, recurrence and patients’ outcome were assessed. Results: A total of 144 patients (142 Caucasian and two Asian) were selected, including 11.27% with EGFR-mutant and 33.10% with KRAS-mutant tumors, and 57.04% patients had developed BM. BM incidence was more frequent in patients with EGFR mutation according to multivariate analyses (MVA) (Odds ratio OR = 8.745 [1.743–43.881], p = 0.008). Among patients with treated BM, recurrence after local treatment was less frequent in patients with KRAS mutation (OR = 0.234 [0.078–0.699], p = 0.009). Among patients with untreated BM, overall survival (OS) was shorter for patients with KRAS mutation according to univariate analysis (OR = 7.130 [1.240–41.012], p = 0.028), but not MVA. Conclusions: EGFR and KRAS mutations have a predictive role on BM incidence, recurrence and outcome in Caucasian NSCLC patients. These results may impact the routine management of disease in these patients. Further studies are required to assess the influence of other biomarkers on NSCLC BM.

Orchestration of the crosstalk between astrocytes and cancer cells affects the treatment and prognosis of lung cancer sufferers with brain metastasis

Brain metastasis is an inauspicious consequence of lung cancer. However, the majority of cancer cells that seep into the brain died of unknown causes, only a few survived and developed into metastatic brain tumor. Communication between cancer cells and host tissue is viewed as an essential event during metastasis, but little is known about the accurate control of this processes. Within the lesion of brain metastasis, abundant activated astrocytes are observed with lung cancer cells. Previous studies have demonstrated that the astrocyte network served a protective role in the central nervous system (CNS) and most malignant cells that seep into the brain perish were rejected by astrocytes. Reactive astrocytes generated protease plasmin and cytotoxic cytokines as a defense against metastatic invasion. But recently, other investigators argued that tumor cells interactions with astrocytes promote the progression of brain metastases and protect them from the cytotoxic effects of chemotherapy. In this article, we review the architecture between astrocytes and infiltrated cancer cells, and raise a future perspective on therapeutic potential of targeting crosstalk modulators against brain metastasis.

[Advances in Bevacizumab Therapy for Non-small Cell Lung Cancer with Brain Metastases]

Brain metastases are frequently encountered in patients with non-small cell lung cancer (NSCLC) and are a significant cause of morbidity and mortality. Antiangiogenesis therapy plays a major role in the management of brain metastases in lung cancer. Bevacizumab have become the novel method for the treatment of lung cancer with brain metastases beyond the whole brain radiation therapy, stereotactic radiosurgery and chemotherapy. Recently, more and more studies and trials laid emphasis on the bevacizumab for NSCLC with brain metastases treatment. The key point is the efficacy and safety. In this review, bevacizumab therapy of NSCLC with brain metastases were summarized.

Erlotinib plus concurrent whole-brain radiation therapy for non-small cell lung cancers patients with multiple brain metastases

Sequencing of the epidermal growth factor receptor (EGFR) gene to identify mutations in lung adenocarcinomas is routine in clinical practice. The use of tyrosine kinase inhibitors (TKIs) has transformed the management of patients with brain metastases harboring EGFR mutations, with improved response rates (RR) and survival. We evaluate the role of concurrent TKI therapy and radiotherapy in this group of patients, considering this data in the context of emerging concepts in this advancing field.

Blood-brain Barrier Remodeling during Brain Metastasis Formation

Our understanding of the process of metastatic progression has improved markedly over the past decades, yet metastasis remains the most enigmatic component of cancer pathogenesis. This lack of knowledge has serious health-related implications, since metastasis is responsible for 90% of all cancer-related mortalities. The brain is considered a sanctuary site for metastatic tumor growth, where the blood-brain barrier (BBB) and other components of the brain microenvironment, provide protection to the tumor cells from immune surveillance, chemotherapeutics and other potentially harmful substances. The interactions between tumor cells and the brain microenvironment, principally brain vascular endothelium, are the critical determinants in their progression toward metastasis, dormancy, or clearance. This review discusses current knowledge of the biology of metastatic progression, with a particular focus on the tumor cell migration and colonization in the brain.

Combined RNAi targeting human Stat3 and ADAM9 as gene therapy for non-small cell lung cancer

Previous studies have demonstrated that human signal transducer and activator of transcription 3 (Stat3) and disintegrin and metalloproteinase 9 (ADAM9) are promising targets for RNA interference (RNAi)-based gene therapy for human non-small cell lung cancer (NSCLC). Thus, in the present study, the recombinant lentiviral (Lv) small hairpin (sh)RNA expression plasmids Lv/sh-Stat3 and Lv/sh-ADAM9, which targeted Stat3 and ADAM9, respectively, were constructed and subsequently infected into the A549 human NSCLC cell line. Cell proliferation, migration, invasion and apoptosis were determined in vitro in A549 cells following treatment with Lv/sh-Stat3 or Lv/sh-ADAM9 alone or in combination. In addition, the combined effect of Lv/sh-Stat3 and Lv/sh-ADAM9 gene therapy was evaluated in vivo using A549 xenograft models in nude mice. The in vitro experiments demonstrated that A549 cells treated with a combination of Lv/sh-Stat3 and Lv/sh-ADAM9 exhibited a significant additive effect in their cell proliferation, migration, invasion and apoptosis abilities, compared with A549 cells treated with Lv/sh-Stat3 or Lv/sh-ADAM9 alone. The in vivo experiments conducted in A549 xenograft tumor mouse models revealed that the combined treatment with Lv/sh-Stat3 and Lv/sh-ADAM9 exerted an additive effect on tumor growth inhibition, compared with the treatment with Lv/sh-Stat3 or Lv/sh-ADAM9 alone. These results suggested that combined RNAi gene therapy targeting human Stat3 and ADAM9 may be a novel and promising strategy for the treatment of NSCLC.

Low expression of dendritic cell-specific intercellular adhesion molecule-grabbing nonintegrin-related protein in lung cancer and significant correlations with brain metastasis and natural killer cells

Dendritic cell-specific intercellular adhesion molecule-grabbing nonintegrin-related protein (DC-SIGNR) is a type II transmembrane protein which has been reported to bind a variety of pathogens as well as participate in immunoregulation. But the association between the level of DC-SIGNR and lung cancer is unknown. To investigate the clinical diagnostic significance of DC-SIGNR in lung cancer, we investigated serum DC-SIGNR levels in 173 lung cancer patients and 134 healthy individuals using enzyme-linked immunosorbent assay (ELISA). Results showed that serum DC-SIGNR levels in lung cancer patients were lower than that in healthy controls (P = 0.0003). A cut-off value of 3.8998 ng/L for DC-SIGNR predicted the presence of lung cancer with 78.03% sensitivity and 49.25% specificity (area under the curve = 0.6212, P = 0.0003). Strikingly, serum DC-SIGNR levels were significantly higher in lung cancer patients with brain metastasis compared to those without metastasis (P = 0.0283). Moreover, the serum concentrations of DC-SIGNR in lung cancer patients also correlated significantly with serum natural killer cells percentage (P = 0.0017). In addition, immunohistochemistry assay demonstrated that the expression of DC-SIGNR in lung tissues of 31 lung cancer patients and 13 tuberculosis patients was significantly lower than that in 18 normal lung tissues (P = 0.0418, 0.0289), and there is no significant difference between tuberculosis tissues and lung cancer tissues (P = 0.2696). These results suggest that DC-SIGNR maybe a promising biological molecule that has the potential for clinical research of lung cancer, whereas its underlying roles are needed to be investigated in further studies.

Significance of Trask protein interactions in brain metastatic cohorts of lung cancers

A class of adhesion protein that occurs in the membrane with both extracellular and intracellular domain and play vital role in maintaining multicellularity is TRASK, also called CUB-domain containing protein1, CD318 (CDCP1). Specifically, in the current study, documented aggressive grades of lung cancers and distant metastatic tissues were examined for protein interactions of Trask and compared with lung cancer variants in situ. The intracellular domain of Trask has the ability to undergo tyrosine phosphorylation and thereafter undergo increased genomic expression, as well as interact with cytoskeletal proteins in the cell periphery and other local signal transduction machinery to induce invadopodia formation and distant metastasis. We incorporated proximity ligation assay to examine protein interactions of Trask in metastatic lung cancer tissues and compare with advanced and low-grade lung cancers restricted to the primary site of origins. Here, we provide direct evidence that activated Trask, which is a phosphorylated form, binds with cytoskeletal proteins actin and spectrin. These interactions were not seen in locally growing lung cancer and cancer in situ. These interactions may be responsible for invadopodia formation and breaking free from a multicellular environment. Functional studies demonstrated interaction between Trask and the STOCs Orai1 and Stim1. Calcium release from internal stores was highest in metastatic lung cancers, suggesting this mechanism as an initial stimulus for the cells to respond chaotically to external growth factor stimulation, especially in aggressive metastatic variants of lung cancers. Recently, inhibitors of STOCs have been identified, and preclinical evidence may be obtained whether these drugs may be of benefit in preventing the deadly consequences of lung cancer.

An active treatment of lung adenocarcinoma cancer with brain metastases: icotinib

Lung cancer has the highest mortality rate of all cancers worldwide. A total of 70%-75% of all lung cancers are non-small cell lung cancer (NSCLC) with two-thirds presenting with locally advanced or metastatic disease at diagnosis. Brain metastasis is one of the most common problems in the management of NSCLC, worsening the prognosis and quality of life of NSCLC patients. The epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) gefitinib and erlotinib have been tested in patients with NSCLC and brain metastasis. Icotinib is a new type of oral EGFR-TKI. In this report, we describe a patient with lung adenocarcinoma cancer with brain metastases who received icotinib treatment and kept satisfactory health-related quality of life for 1 year.