LKB1 loss cooperating with BRAF V600E promotes melanoma cell invasion and migration by up-regulation MMP-2 via PI3K/Akt/mTOR pathway

LKB1 Loss Correlates with STING Loss and, in Cooperation with β-Catenin Membranous Loss, Indicates Poor Prognosis in Patients with Operable Non-Small Cell Lung Cancer

To investigate the incidence and prognostically significant correlations and cooperations of LKB1 loss of expression in non-small cell lung cancer (NSCLC), surgical specimens from 188 metastatic and 60 non-metastatic operable stage I-IIIA NSCLC patients were analyzed to evaluate their expression of LKB1 and pAMPK proteins in relation to various processes. The investigated factors included antitumor immunity response regulators STING and PD-L1; pro-angiogenic, EMT and cell cycle targets, as well as metastasis-related (VEGFC, PDGFRα, PDGFRβ, p53, p16, Cyclin D1, ZEB1, CD24) targets; and cell adhesion (β-catenin) molecules. The protein expression levels were evaluated via immunohistochemistry; the RNA levels of LKB1 and NEDD9 were evaluated via PCR, while KRAS exon 2 and BRAFV600E mutations were evaluated by Sanger sequencing. Overall, loss of LKB1 protein expression was observed in 21% (51/248) patients and correlated significantly with histotype (p < 0.001), KRAS mutations (p < 0.001), KC status (concomitant KRAS mutation and p16 downregulation) (p < 0.001), STING loss (p < 0.001), and high CD24 expression (p < 0.001). STING loss also correlated significantly with loss of LKB1 expression in the metastatic setting both overall (p = 0.014) and in lung adenocarcinomas (LUACs) (p = 0.005). Additionally, LKB1 loss correlated significantly with a lack of or low β-catenin membranous expression exclusively in LUACs, both independently of the metastatic status (p = 0.019) and in the metastatic setting (p = 0.007). Patients with tumors yielding LKB1 loss and concomitant nonexistent or low β-catenin membrane expression experienced significantly inferior median overall survival of 20.50 vs. 52.99 months; p < 0.001 as well as significantly greater risk of death (HR: 3.32, 95% c.i.: 1.71-6.43; p <0.001). Our findings underscore the impact of the synergy of LKB1 with STING and β-catenin in NSCLC, in prognosis.

Multidrug resistance in the standardized treatment of colon cancer harboring a rare fibrosarcoma B-type (BRAF) p.N581I mutation: a case report

BRAF non-V600 mutations are a distinct molecular subset of colorectal cancer (CRC) that has little to no clinical similarity to the BRAF V600 mutations. It is generally considered that the BRAF non-V600 mutations correlate with better survival of CRC patients. In this report, we present an unusual case of that a midlife female patient who was initially diagnosed with stage IIIC colon cancer, and multiple metastases were found 25 months after radical surgery. Next-generation sequencing (NGS) revealed the BRAF p.N581I (c.1742A>T) mutation. She received chemotherapy, targeted therapy, and immunotherapy. However, the disease progressed rapidly with rare metastasis of the bone and cerebellum. This case highlights that the BRAF non-V600 mutations, such as BRAF p.N581I mutant, may lead to resistance to epidermal growth factor receptor (EGFR) inhibitors and result in a rapid course in colorectal cancer. The role of BRAF p.N581I mutation in colorectal cancer demands more attention.

MicroRNA-150-5p inhibits the proliferation and invasion of human larynx epidermiod cancer cells though regulating peptidyl-prolyl cis/trans isomerase

OBJECTIVE

This study aimed to investigate the molecular mechanism of miR-150-5p regulating the malignant biological behavior of Human Epidermoid cancer cell (HEp-2) by targeting peptidyl-prolyl cis/trans isomerase NIMA-Interacting-1 (PIN1).

METHODS

Firstly, qRT-PCR and Western blot were adopted to detect the expression levels of miR-150-5p and PIN1 in cancer tissue and paracancerous tissues of patients with LSCC, and those in human bronchial epithelial cells (16 HBE) and HEp-2. Next, the targeted relationship between miR-150-5p and PIN1 was assessed by bioinformatics website and dual-luciferase reporter assay, followed by their correlation analysis. Besides, after interfering with miR-150-5p or PIN1 expression in HEp-2 cells, CCK-8, cell colony formation assay, and transwell assay were utilized to detect the proliferation, viability, and invasion of cells, respectively. Subsequently, the protein levels of MMP-2, MMP-9, and EMT-related proteins in HEp-2 cells were checked by Western blot.

RESULTS

Expression of miR-150-5p was down-regulated in LSCC tissues and HEp-2 cells. Moreover, miR-150-5p suppressed proliferation and invasion of HEp-2 cells, affected protein expression related to MMP and EMT, thereby inhibiting development of cancer. The expression of PIN1 was significantly increased in cancer tissues and HEp-2 cells, and there was a targeted relationship and negative correlation between miR-150-5p and PIN1 in cancer tissue. However, overexpression of PIN1 could reverse the effect of miR-150-5p on the proliferation and invasion of HEp-2 cells.

CONCLUSION

In a nutshell, there is a targeted relationship between PIN1 and miR-150-5p. Besides, miR-150-5p can inhibit the proliferation and invasion of HEp-2 cells by regulating the expression of PIN1.

LEVEL OF EVIDENCE: 3

Role of STK11 in ALK‑positive non‑small cell lung cancer (Review)

Anaplastic lymphoma kinase (ALK) inhibitors have been shown to be effective in treating patients with ALK-positive non-small cell lung cancer (NSCLC), and crizotinib, ceritinib and alectinib have been approved as clinical first-line therapeutic agents. The availability of these inhibitors has also largely changed the treatment strategy for advanced ALK-positive NSCLC. However, patients still inevitably develop resistance to ALK inhibitors, leading to tumor recurrence or metastasis. The most critical issues that need to be addressed in the current treatment of ALK-positive NSCLC include the high cost of targeted inhibitors and the potential for increased toxicity and resistance to combination therapy. Recently, it has been suggested that the serine/threonine kinase 11 (STK11) mutation may serve as one of the biomarkers for immunotherapy in NSCLC. Therefore, the main purpose of this review was to summarize the role of STK11 in ALK-positive NSCLC. The present review also summarizes the treatment and drug resistance studies in ALK-positive NSCLC and the current status of STK11 research in NSCLC.

STK11/LKB1 Modulation of the Immune Response in Lung Cancer: From Biology to Therapeutic Impact

The STK11/LKB1 gene codes for liver kinase B1 (STK11/LKB1), a highly conserved serine/threonine kinase involved in many energy-related cellular processes. The canonical tumor-suppressive role for STK11/LKB1 involves the activation of AMPK-related kinases, a master regulator of cell survival during stress conditions. In pre-clinical models, inactivation of STK11/LKB1 leads to the progression of lung cancer with the acquisition of metastatic properties. Moreover, preclinical and clinical data have shown that inactivation of STK11/LKB1 is associated with an inert tumor immune microenvironment, with a reduced density of infiltrating cytotoxic CD8⁺ T lymphocytes, a lower expression of PD-(L)1, and a neutrophil-enriched tumor microenvironment. In this review, we first describe the biological function of STK11/LKB1 and the role of its inactivation in cancer cells. We report descriptive epidemiology, co-occurring genomic alterations, and prognostic impact for lung cancer patients. Finally, we discuss recent data based on pre-clinical models and lung cancer cohorts analyzing the results of STK11/LKB1 alterations on the immune system and response or resistance to immune checkpoint inhibitors.

Molecular Signature Expands the Landscape of Driver Negative Thyroid Cancers

Thyroid cancer is the most common endocrine malignancy. However, the cytological diagnosis of follicular thyroid carcinoma (FTC), Hürthle cell carcinoma (HCC), and follicular variant of papillary thyroid carcinoma (FVPTC) and their benign counterparts is a challenge for preoperative diagnosis. Nearly 20-30% of biopsied thyroid nodules are classified as having indeterminate risk of malignancy and incur costs to the health care system. Based on that, 120 patients were screened for the main driver mutations previously described in thyroid cancer. Subsequently, 14 mutation-negative cases that are the main source of diagnostic errors (FTC, HCC, or FVPTC) underwent RNA-Sequencing analysis. Somatic variants in candidate driver genes (ECD, NUP98,LRP1B, NCOR1, ATM, SOS1, and SPOP) and fusions were described. NCOR1 and SPOP variants underwent validation. Moreover, expression profiling of driver-negative samples was compared to 16 BRAF V600E, RAS, or PAX8-PPARg positive samples. Negative samples were separated in two clusters, following the expression pattern of the RAS/PAX8-PPARg or BRAF V600E positive samples. Both negative groups showed distinct BRS, ERK, and TDS scores, tumor mutation burden, signaling pathways and immune cell profile. Altogether, here we report novel gene variants and describe cancer-related pathways that might impact preoperative diagnosis and provide insights into thyroid tumor biology.

The protein kinase LKB1 promotes self-renewal and blocks invasiveness in glioblastoma

The role of liver kinase B1 (LKB1) in glioblastoma (GBM) development remains poorly understood. LKB1 may regulate GBM cell metabolism and has been suggested to promote glioma invasiveness. After analyzing LKB1 expression in GBM patient mRNA databases and in tumor tissue via multiparametric immunohistochemistry, we observed that LKB1 was localized and enriched in GBM tumor cells that co-expressed SOX2 and NESTIN stemness markers. Thus, LKB1-specific immunohistochemistry can potentially reveal subpopulations of stem-like cells, advancing GBM patient molecular pathology. We further analyzed the functions of LKB1 in patient-derived GBM cultures under defined serum-free conditions. Silencing of endogenous LKB1 impaired 3D-gliomasphere frequency and promoted GBM cell invasion in vitro and in the zebrafish collagenous tail after extravasation of circulating GBM cells. Moreover, loss of LKB1 function revealed mitochondrial dysfunction resulting in decreased ATP levels. Treatment with the clinically used drug metformin impaired 3D-gliomasphere formation and enhanced cytotoxicity induced by temozolomide, the primary chemotherapeutic drug against GBM. The IC₅₀ of temozolomide in the GBM cultures was significantly decreased in the presence of metformin. This combinatorial effect was further enhanced after LKB1 silencing, which at least partially, was due to increased apoptosis. The expression of genes involved in the maintenance of tumor stemness, such as growth factors and their receptors, including members of the platelet-derived growth factor (PDGF) family, was suppressed after LKB1 silencing. The defect in gliomasphere growth caused by LKB1 silencing was bypassed after supplementing the cells with exogenous PFDGF-BB. Our data support the parallel roles of LKB1 in maintaining mitochondrial homeostasis, 3D-gliomasphere survival, and hindering migration in GBM. Thus, the natural loss of, or pharmacological interference with LKB1 function, may be associated with benefits in patient survival but could result in tumor spread.

V600EBRAF Inhibition Induces Cytoprotective Autophagy through AMPK in Thyroid Cancer Cells

The dysregulation of autophagy is important in the development of many cancers, including thyroid cancer, where ^V600EBRAF is a main oncogene. Here, we analyse the effect of ^V600EBRAF inhibition on autophagy, the mechanisms involved in this regulation and the role of autophagy in cell survival of thyroid cancer cells. We reveal that the inhibition of ^V600EBRAF activity with its specific inhibitor PLX4720 or the depletion of its expression by siRNA induces autophagy in thyroid tumour cells. We show that ^V600EBRAF downregulation increases LKB1-AMPK signalling and decreases mTOR activity through a MEK/ERK-dependent mechanism. Moreover, we demonstrate that PLX4720 activates ULK1 and increases autophagy through the activation of the AMPK-ULK1 pathway, but not by the inhibition of mTOR. In addition, we find that autophagy blockade decreases cell viability and sensitize thyroid cancer cells to ^V600EBRAF inhibition by PLX4720 treatment. Finally, we generate a thyroid xenograft model to demonstrate that autophagy inhibition synergistically enhances the anti-proliferative and pro-apoptotic effects of ^V600EBRAF inhibition in vivo. Collectively, we uncover a new role of AMPK in mediating the induction of cytoprotective autophagy by ^V600EBRAF inhibition. In addition, these data establish a rationale for designing an integrated therapy targeting ^V600EBRAF and the LKB1-AMPK-ULK1-autophagy axis for the treatment of ^V600EBRAF-positive thyroid tumours.

Analysis of candidate genes expected to be essential for melanoma surviving

Introduction

Cancers may be treated by selective targeting of the genes vital for their survival. A number of attempts have led to discovery of several genes essential for surviving of tumor cells of different types. In this work, we tried to analyze genes that were previously predicted to be essential for melanoma surviving. Here we present the results of transient siRNA-mediated knockdown of the four of such genes, namely, UNC45A, STK11IP, RHPN2 and ZNFX1, in melanoma cell line A375, then assayed the cells for their viability, proliferation and ability to migrate in vitro. In our study, the knockdown of the genes predicted as essential for melanoma survival does not lead to statistically significant changes in cell viability. On the other hand, for each of the studied genes, mobility assays showed that the knockdown of each of the target genes accelerates the speed of cells migrating. Possible explanation for such counterintuitive results may include insufficiency of the predicting computational models or the necessity of a multiplex knockdown of the genes.

Aims

To examine the hypothesis of essentiality of hypomutated genes for melanoma surviving we have performed knockdown of several genes in melanoma cell line and analyzed cell viability and their ability to migrate.

Methods

Knockdown was performed by siRNAs transfected by Metafectene PRO. The levels of mRNAs before and after knockdown were evaluated by RT-qPCR analysis. Cell viability and proliferation were assessed by MTT assay. Cell migration was assessed by wound healing assay.

Results

The knockdown of the genes predicted as essential for melanoma survival does not lead to statistically significant changes in cell viability. On the other hand, for each of the studied genes, mobility assays showed that the knockdown of each of the target genes accelerates the speed of cells migrating.

Conclusion

Our results do not confirm initial hypothesis that the genes predicted essential for melanoma survival as a matter of fact support the survival of melanoma cells.

HPV16 E6/E7 promote the translocation and glucose uptake of GLUT1 by PI3K/AKT pathway via relieving miR-451 inhibitory effect on CAB39 in lung cancer cells

Background

HPV16 E6/E7 proteins are the main oncogenes and only long-term persistent infection causes lung cancer. Our previous studies have shown that HPV16 E6/E7 protein up-regulates the expression of GLUT1 in lung cancer cells. However, whether E6 and E7 protein can promote the glucose uptake of GLUT1 and its molecular mechanism are unclear.

Methods

The regulatory relationships of E6 or E7, miR-451, CAB39, PI3K/AKT, and GLUT1 were detected by double directional genetic manipulations in lung cancer cell lines. Immunofluorescence and flow cytometry were used to detect the effect of CAB39 on promoting the translocation to the plasma membrane of GLUT1. Flow cytometry and confocal microscopy were performed to detect the glucose uptake levels of GLUT1.

Results

The overexpression both E6 and E7 proteins significantly down-regulated the expression level of miR-451, and the loss of miR-451 further up-regulated the expression of its target gene CAB39 at both protein and mRNA levels. Subsequently, CAB39 up-regulated the expression of GLUT1 at both protein and mRNA levels. Our results demonstrated that HPV16 E6/E7 up-regulated the expression and activation of GLUT1 through the HPV-miR-451-CAB39-GLUT1 axis. More interestingly, we found that CAB39 prompted GLUT1 translocation to the plasma membrane and glucose uptake, and this promotion depended on the PI3K/AKT pathway.

Conclusion

Our findings provide new evidence to support the critical roles of miR-451 and CAB39 in the pathogenesis of HPV-related lung cancer.

Loss of Spry1 reduces growth of BRAFV600-mutant cutaneous melanoma and improves response to targeted therapy

Mitogen-activated protein kinase (MAPK) pathway activation is a central step in BRAF^V600-mutant cutaneous melanoma (CM) pathogenesis. In the last years, Spry1 has been frequently described as an upstream regulator of MAPK signaling pathway. However, its specific role in BRAF^V600-mutant CM is still poorly defined. Here, we report that Spry1 knockdown (Spry1^KO) in three BRAF^V600-mutant CM cell lines markedly induced cell cycle arrest and apoptosis, repressed cell proliferation in vitro, and impaired tumor growth in vivo. Furthermore, our findings indicated that Spry1^KO reduced the expression of several markers of epithelial–mesenchymal transition, such as MMP-2 both in vitro and in vivo. These effects were associated with a sustained and deleterious phosphorylation of ERK1/2. In addition, p38 activation along with an increase in basal ROS levels were found in Spry1^KO clones compared to parental CM cell lines, suggesting that BRAF^V600-mutant CM may restrain the activity of Spry1 to avoid oncogenic stress and to enable tumor growth. Consistent with this hypothesis, treatment with the BRAF inhibitor (BRAFi) vemurafenib down-regulated Spry1 levels in parental CM cell lines, indicating that Spry1 expression is sustained by the MAPK/ERK signaling pathway in a positive feedback loop that safeguards cells from the potentially toxic effects of ERK1/2 hyperactivation. Disruption of this feedback loop rendered Spry1^KO cells more susceptible to apoptosis and markedly improved response to BRAFi both in vitro and in vivo, as a consequence of the detrimental effect of ERK1/2 hyperactivation observed upon Spry1 abrogation. Therefore, targeting Spry1 might offer a treatment strategy for BRAF^V600-mutant CM by inducing the toxic effects of ERK-mediated signaling.

lncRNA MIAT promotes cell invasion and migration in esophageal cancer

Long non-coding RNAs (lncRNAs) serve crucial roles in carcinogenesis. Myocardial infarction-associated transcript (MIAT), originally isolated as a candidate gene for myocardial infarction, has been revealed to serve as an oncogene in chronic lymphocytic leukaemias and neuroendocrine prostate cancer. However, little is known about its expression pattern, biological function and underlying mechanism in esophageal cancer. Cell lines of esophageal cancer were used in the current study. The results of the present study revealed that MIAT knockdown decreased cell viability, migration, invasion and cell cycle arrest in the G1 phase. Mechanistic assessment revealed that MIAT interacts with histone methyltransferase mixed-lineage leukemia (MLL). The relative proteins expressions were measured by western blotting assay. MIAT knockdown suppressed cell invasion and migration by regulation MMP-2/9 protein expressions. The results of the current study indicated that MIAT expression was associated with esophageal cancer and may serve as a critical target in the progression and metastasis in esophageal cancer.

Matrix metalloproteinases MMP-1, MMP-2, and MMP-13 are overexpressed in primary nodular melanoma

BACKGROUND

The spread and invasion of malignant melanoma cells involve degradation and reorganization of the extracellular matrix by the activation of several matrix metalloproteinases (MMPs). This study analyzed the expression of MMP-1, MMP-2, and MMP-13 proteins in primary nodular melanoma (NM) and dysplastic nevi (DN) as a significant risk factor for melanoma development. The secondary goal was to analyze the correlation of MMPs protein expression in NM with tumor invasion, BRAF V600 mutation status, and overall survival.

METHODS

Immunohistochemistry for MMP-1, MMP-2, and MMP-13 was performed on nodular melanoma (n = 52) and dysplastic nevi (n = 28) on tissue microarray (TMA). BRAF V600 mutation analysis on NM samples was performed by the Sanger sequencing method.

RESULTS

A high level of MMPs expression in NM samples (>30%) compared with DN (<8%) was statistically significant (P < 0.001). BRAF V600 mutations were detected in 15 of 39 (38.5%) NM samples. This study revealed an interesting finding that MMP-1 and MMP-13 protein expression in the BRAF V600 mutated melanomas were significantly lower than in the BRAF V600 wild type (P < 0.05).

CONCLUSION

Cox analysis revealed that Clark categories, Breslow thickness, and MMP-1 high protein expression are predictive factors for shorter overall survival (P < 0.05).

The Chemosensory Function of Primary Cilia Regulates Cholangiocyte Migration, Invasion, and Tumor Growth

Cholangiocytes, the epithelial cells lining the biliary tree in the liver, express primary cilia that can detect several kinds of environmental signals and then transmit this information into the cell. We have reported that cilia are significantly reduced in cholangiocarcinoma (CCA) and that the experimental deciliation of normal cells induces a malignant-like phenotype with increased proliferation, anchorage-independent growth, invasion, and migration. Here, we tested the hypothesis that the chemosensory function of cholangiocyte primary cilia acts as a mechanism for tumor suppression. We found that in the presence of extracellular nucleotides cilia-dependent chemosensation of the nucleotides inhibited migration and invasion in normal ciliated cholangiocytes through a P2Y11 receptor and liver kinase B1 (LKB1)-phosphatase and tensin homolog-AKT-dependent mechanism. In contrast, in normal deciliated cholangiocytes and CCA cells, the nucleotides induced the opposite effects, i.e., increased migration and invasion. As activation of LKB1 through a cilia-dependent mechanism was required for the nucleotide-mediated inhibitory effects on migration and invasion, we attempted to activate LKB1 directly, independent of ciliary expression, using the compound hesperidin methyl chalcone (HMC). We found that HMC induced activation of LKB1 in both ciliated and deciliated cells in vitro, resulting in the inhibition of migration and proliferation. Furthermore, using a rat syngeneic orthotopic CCA model, we found that HMC inhibited tumor growth in vivo. Conclusion: These findings highlight the importance of the chemosensory function of primary cilia for the control of migration and invasion and suggest that, by directly activating LKB1 and bypassing the need for primary cilia, it is possible to emulate this chemosensory function in CCA cells; these data warrant further studies evaluating the possibility of using HMC as therapy for CCA.