Modulation of septin and molecular motor recruitment in the microtubule environment of the Taxol-resistant human breast cancer cell line MDA-MB-231

The Actin Motor Protein Myosin 6 Contributes to Cell Migration and Expression of GIPC1 and Septins in Breast Cancer Cells

Introduction

Breast cancer is highly metastatic. One protein that may participate in breast cancer cell migration is the actin motor protein myosin 6 (MYO6), which is likely regulated by the GIPC1 protein. Additionally, septins (SEPTs) appear to participate in breast cancer motility. Here, we investigated the effects of loss of MYO6 on cell morphology, migration, and expression of GIPC1, SEPT2, and SEPT7 in two breast cancer cell lines.

Material and Methods

The research material consisted of two breast cancer cell lines, MCF-7 and MDA-MB-231, in which the level of MYO6 was reduced and the effect of knockdown on the migration potential and the expression of GIPC1, SEPT2 and SEPT7 was determined. The levels of these proteins were also analyzed in silico.

Results

siRNA-mediated knock down of MYO6 altered the morphology of MCF-7 cells and reduced the expression of GIPC1 and SEPT7 in both MCF-7 and MDA-MB-231 cells. In in silico data, GIPC1, SEPT2, and SEPT7 were all overexpressed in breast cancer tissue samples from patients. Finally, MYO6 knock down impaired migration and adhesion in both MCF-7 and MDA-MB-231 cells.

Conclusion

Our study substantiates that downregulation of MYO6 diminishes the migratory abilities of breast cancer cell lines with varying invasiveness. Furthermore, we have demonstrated that decreased MYO6 protein leads to reduced expression of GIPC1, SEPT2, and SEPT7 in breast cancer cells. These findings contribute to a more comprehensive understanding of the pathways influencing breast cancer cell migration, a critical aspect of metastasis.

Septin-coated microtubules promote maturation of multivesicular bodies by inhibiting their motility

The microtubule cytoskeleton consists of microtubule subsets with distinct compositions of microtubule-associated proteins, which instruct the position and traffic of subcellular organelles. In the endocytic pathway, these microtubule-associated cues are poorly understood. Here, we report that in MDCK cells, endosomes with multivesicular body (MVB) and late endosome (LE) markers localize preferentially to microtubules coated with septin GTPases. Compared with early endosomes, CD63-containing MVBs/LEs are largely immotile on septin-coated microtubules. In vitro reconstitution assays revealed that the motility of isolated GFP-CD63 endosomes is directly inhibited by microtubule-associated septins. Quantification of CD63-positive endosomes containing the early endosome antigen (EEA1), the Rab7 effector and dynein adaptor RILP or Rab27a, showed that intermediary EEA1- and RILP-positive GFP-CD63 preferentially associate with septin-coated microtubules. Septin knockdown enhanced GFP-CD63 motility and decreased the percentage of CD63-positive MVBs/LEs with lysobiphosphatidic acid without impacting the fraction of EEA1-positive CD63. These results suggest that MVB maturation involves immobilization on septin-coated microtubules, which may facilitate multivesiculation and/or organelle-organelle contacts.

Proteomic profiling of the oncogenic septin 9 reveals isoform-specific interactions in breast cancer cells

Septins are a family of multimeric GTP-binding proteins, which are abnormally expressed in cancer. Septin 9 (SEPT9) is an essential and ubiquitously expressed septin with multiple isoforms, which have differential expression patterns and effects in breast cancer cells. It is unknown, however, if SEPT9 isoforms associate with different molecular networks and functions. Here, we performed a proteomic screen in MCF-7 breast cancer cells to identify the interactome of GFP-SEPT9 isoforms 1, 4 and 5, which vary significantly in their N-terminal extensions. While all three isoforms associated with SEPT2 and SEPT7, the truncated SEPT9_i4 and SEPT9_i5 interacted with septins of the SEPT6 group more promiscuously than SEPT9_i1, which bound predominately SEPT8. Spatial mapping and functional clustering of non-septin partners showed isoform-specific differences in interactions with proteins of distinct subcellular organelles (e.g., nuclei, centrosomes, cilia) and functions such as cell signalling and ubiquitination. The interactome of the full length SEPT9_i1 was more enriched in cytoskeletal regulators, while the truncated SEPT9_i4 and SEPT9_i5 exhibited preferential and isoform-specific interactions with nuclear, signalling, and ubiquitinating proteins. These data provide evidence for isoform-specific interactions, which arise from truncations in the N-terminal extensions of SEPT9, and point to novel roles in the pathogenesis of breast cancer.

Cdc42 and its BORG2 and BORG3 effectors control the subcellular localization of septins between actin stress fibers and microtubules

Cell resistance to taxanes involves several complementary mechanisms, among which septin relocalization from actin stress fibers to microtubules plays an early role. By investigating the molecular mechanism underlying this relocalization, we found that acute paclitaxel treatment triggers the release from stress fibers and subsequent proteasome-mediated degradation of binder of Rho GTPases 2 (BORG2)/Cdc42 effector protein 3 (Cdc42EP3) and to a lesser extent of BORG3/Cdc42EP5, two Cdc42 effectors that link septins to actin in interphase cells. BORG2 or BORG3 silencing not only caused septin detachment from stress fibers but also mimicked the effects of paclitaxel by triggering both septin relocalization to microtubules and significant drug resistance. Conversely, BORG2 or BORG3 overexpression retained septins on actin fibers even after paclitaxel treatment, without affecting paclitaxel sensitivity. We found that drug-induced inhibition of Cdc42 resulted in a drop in BORG2 level and in the relocalization of septins to microtubules. Accordingly, although septins relocalized when overexpressing an inactive mutant of Cdc42, the expression of a constitutively active mutant acted locally at actin stress fibers to prevent septin release, even after paclitaxel treatment. These findings reveal the role of Cdc42 upstream of BORG2 and BORG3 in controlling the interplay between septins, actin fibers, and microtubules in basal condition and in response to taxanes.

Spatial regulation of microtubule-dependent transport by septin GTPases

The intracellular long-range transport of membrane vesicles and organelles is mediated by microtubule motors (kinesins, dynein) which move cargo with spatiotemporal accuracy and efficiency. How motors navigate the microtubule network and coordinate their activity on membrane cargo are fundamental but poorly understood questions. New studies show that microtubule-dependent membrane traffic is spatially controlled by septins - a unique family of multimerizing GTPases that associate with microtubules and membrane organelles. We review how septins selectively regulate motor interactions with microtubules and membrane cargo. We posit that septins provide a novel traffic code that specifies the movement and directionality of select motor-cargo complexes on distinct microtubule tracks.

The LncRNA FGD5-AS1/miR-497-5p axis regulates septin 2 (SEPT2) to accelerate cancer progression and increase cisplatin-resistance in laryngeal squamous cell carcinoma

Aberrant expression or mutation of the Septin gene family is closely associated with cancer progression, and septin 2 (SEPT2) exerts its tumor-promoting effects in multiple cancers, but its role in regulating laryngeal squamous cell carcinoma (LSCC) progression and drug resistance has not been investigated. Based on the published data, the present study identified that SEPT2 promoted cancer progression and increased cisplatin-resistance in LSCC, and a novel LncRNA FGD5-AS1/miR-497-5p axis was crucial for this process. Mechanistically, SEPT2 tended to be enriched in LSCC tissues and cells, and knock-down of SEPT2 inhibited cell proliferation, viability, migration, and tumorigenesis in LSCC cells in vitro and in vivo. Aside from that, SEPT2 overexpression increased cisplatin resistance in LSCC cells. Next, by conducting the dual-luciferase reporter gene system assay, we identified that the LncRNA FGD5-AS1/miR-497-5p axis regulated SEPT2 in LSCC. Specifically, LncRNA FGD5-AS1 sponged miR-497-5p to upregulate SEPT2 in LSCC cells in a competing endogenous RNA (ceRNA) mechanisms-dependent manner. Interestingly, upregulated LncRNA FGD5-AS1 and downregulated miR-497-5p were observed in LSCC tissues and cells, and LncRNA FGD5-AS1 ablation inhibited cancer progression. Also, LncRNA FGD5-AS1 overexpression increased cisplatin-resistance in LSCC by modulating the miR-497-5p/SEPT2 axis. Collectively, we conclude that targeting the LncRNA FGD5-AS1/miR-497-5p/SEPT2 signaling cascade may be an alternative strategy to treat LSCC in the clinic.

Cellular functions of actin- and microtubule-associated septins

Septins are an integral component of the cytoskeleton, assembling into higher-order oligomers and filamentous polymers that associate with actin filaments, microtubules and membranes. Here, we review septin interactions with actin and microtubules, and septin-mediated regulation of the organization and dynamics of these cytoskeletal networks, which is critical for cellular morphogenesis. We discuss how actomyosin-associated septins function in cytokinesis, cell migration and host defense against pathogens. We highlight newly emerged roles of septins at the interface of microtubules and membranes with molecular motors, which point to a 'septin code' for the regulation of membrane traffic. Additionally, we revisit the functions of microtubule-associated septins in mitosis and meiosis. In sum, septins comprise a unique module of cytoskeletal regulators that are spatially and functionally specialized and have properties of bona fide actin-binding and microtubule-associated proteins. With many questions still outstanding, the study of septins will continue to provide new insights into fundamental problems of cytoskeletal organization and function.

Structure and function of Septin 9 and its role in human malignant tumors

The treatment and prognosis of malignant tumors are closely related to the time when the tumors are diagnosed; the earlier the diagnosis of the tumor, the better the prognosis. However, most tumors are not detected in the early stages of screening and diagnosis. It is of great clinical significance to study the correlation between multiple pathogeneses of tumors and explore simple, safe, specific, and sensitive molecular indicators for early screening, diagnosis, and prognosis. The Septin 9 (SEPT9) gene has been found to be associated with a variety of human diseases, and it plays a role in the development of tumors. SEPT9 is a member of the conserved family of cytoskeletal GTPase, which consists of a P-loop-based GTP-binding domain flanked by a variable N-terminal region and a C-terminal region. SEPT9 is involved in many biological processes such as cytokinesis, polarization, vesicle trafficking, membrane reconstruction, deoxyribonucleic acid repair, cell migration, and apoptosis. Several studies have shown that SEPT9 may serve as a marker for early screening, diagnosis, and prognosis of some malignant tumors, and have the potential to become a new target for anti-cancer therapy. This article reviews the progress in research on the SEPT9 gene in early screening, diagnosis, and prognosis of tumors.

Overexpression of kinesin superfamily members as prognostic biomarkers of breast cancer

BACKGROUND

Kinesin superfamily (KIFs) has a long-reported significant influence on the initiation, development, and progress of breast cancer. However, the prognostic value of whole family members was poorly done. Our study intends to demonstrate the value of kinesin superfamily members as prognostic biomarkers as well as a therapeutic target of breast cancer.

METHODS

Comprehensive bioinformatics analyses were done using data from TCGA, GEO, METABRIC, and GTEx. LASSO regression was done to select tumor-related members. Nomogram was constructed to predict the overall survival (OS) of breast cancer patients. Expression profiles were testified by quantitative RT-PCR and immunohistochemistry. Transcription factor, GO and KEGG enrichments were done to explore regulatory mechanism and functions.

RESULTS

A total of 20 differentially expressed KIFs were identified between breast cancer and normal tissue with 4 (KIF17, KIF26A, KIF7, KIFC3) downregulated and 16 (KIF10, KIF11, KIF14, KIF15, KIF18A, KIF18B, KIF20A, KIF20B, KIF22, KIF23, KIF24, KIF26B, KIF2C, KIF3B, KIF4A, KIFC1) overexpressed. Among which, 11 overexpressed KIFs (KIF10, KIF11, KIF14, KIF15, KIF18A, KIF18B, KIF20A, KIF23, KIF2C, KIF4A, KIFC1) significantly correlated with worse OS, relapse-free survival (RFS) and distant metastasis-free survival (DMFS) of breast cancer. A 6-KIFs-based risk score (KIF10, KIF15, KIF18A, KIF18B, KIF20A, KIF4A) was generated by LASSO regression with a nomogram validated an accurate predictive efficacy. Both mRNA and protein expression of KIFs are experimentally demonstrated upregulated in breast cancer patients. Msh Homeobox 1 (MSX1) was identified as transcription factors of KIFs in breast cancer. GO and KEGG enrichments revealed functions and pathways affected in breast cancer.

CONCLUSION

Overexpression of tumor-related KIFs correlate with worse outcomes of breast cancer patients and can work as potential prognostic biomarkers.

[10]-Gingerol Affects Multiple Metastatic Processes and Induces Apoptosis in MDAMB- 231 Breast Tumor Cells

Background:

Triple Negative Breast Cancer (TNBC) represents the approximately 15% of breast cancers that lack expression of Estrogen (ER) and Progesterone Receptors (PR) and do not exhibit amplification of the human epidermal growth factor receptor 2 (HER2) gene, imposing difficulties to treatment. Interactions between tumor cells and their microenvironment facilitate tumor cell invasion in the surrounding tissues, intravasation through newly formed vessels, and dissemination to form metastasis. To treat metastasis from breast and many other cancer types, chemotherapy is one of the most extensively used methods. However, its efficacy and safety remain a primary concern, as well as its toxicity and other side effects. Thus, there is increasing interest in natural antitumor agents. In a previous work, we have demonstrated that [10]-gingerol is able to revert malignant phenotype in breast cancer cells in 3D culture and, moreover, to inhibit the dissemination of TNBC to multiple organs including lung, bone and brain, in spontaneous and experimental in vivo metastasis assays in mouse model.

Objective:

This work aims to investigate the in vitro effects of [10]-gingerol, using human MDA-MB-231TNBC cells, in comparison to non-tumor MCF-10A breast cells, in order to understand the antitumor and antimetastatic effects found in vivo and in a 3D environment.

Methods:

We investigated different steps of the metastatic process in vitro, such as cell migration, invasion, adhesion and MMP activity. In addition, we analyzed the anti-apoptotic and genotoxic effects of [10]-gingerol using PEAnnexin, DNA fragmentation, TUNEL and comet assays, respectively.

Results:

[10]-gingerol was able to inhibit cell adhesion, migration, invasion and to induce apoptosis more effectively in TNBC cells, when compared to non-tumor cells, demonstrating that these mechanisms can be involved in the antitumor and antimetastatic effects of [10]-gingerol, found both in 3D culture and in vivo.

Conclusion:

Taken together, results found here are complementary to previous studies of our group and others and demonstrate that additional mechanisms, besides apoptotic cell death, is used by [10]-gingerol to accomplish its antitumor and antimetastatic effects. Our results indicate a potential for this natural compound as an antitumor molecule or as an adjuvant for chemotherapeutics already used in the clinic.

Septin filament coalignment with microtubules depends on SEPT9_i1 and tubulin polyglutamylation, and is an early feature of acquired cell resistance to paclitaxel

Cancer cell resistance to taxanes is a complex, multifactorial process, which results from the combination of several molecular and cellular changes. In breast cancer cells adapted to long-term paclitaxel treatment, we previously identified a new adaptive mechanism that contributes to resistance and involves high levels of tubulin tyrosination and long-chain polyglutamylation coupled with high levels of septin expression, especially that of SEPT9_i1. This in turn led to higher CLIP-170 and MCAK recruitment to microtubules to enhance microtubule dynamics and therefore counteract the stabilizing effects of taxanes. Here, we explored to which extent this new mechanism alone could trigger taxane resistance. We show that coupling septins (including SEPT9_i1) overexpression together with long-chain tubulin polyglutamylation induce significant paclitaxel resistance in several naive (taxane-sensitive) cell lines and accordingly stimulate the binding of CLIP-170 and MCAK to microtubules. Strikingly, such resistance was paralleled by a systematic relocalization of septin filaments from actin fibers to microtubules. We further show that this relocalization resulted from the overexpression of septins in a context of enhanced tubulin polyglutamylation and reveal that it could also be promoted by an acute treatment with paclitaxel of sensitve cell displaying a high basal level of SEPT9_i1. These findings point out the functional importance and the complex cellular dynamics of septins in the onset of cell resistance to death caused by microtubule-targeting antimitotic drugs of the taxane family.

Repression of Septin9 and Septin2 suppresses tumor growth of human glioblastoma cells

Glioblastoma (GBM) is the most common primary malignancy of the central nervous system (CNS) with <10% 5-year survival rate. The growth and invasion of GBM cells into normal brain make the resection and treatment difficult. A better understanding of the biology of GBM cells is crucial to the targeted therapies for the disease. In this study, we identified Septin9 (SEPT9) and Septin2 (SEPT2) as GBM-related genes through integrated multi-omics analysis across independent transcriptomic and proteomic studies. Further studies revealed that expression of SEPT9 and SEPT2 was elevated in glioma tissues and cell lines (A172, U87-MG). Knockdown of SEPT9 and SEPT2 in A172/U87-MG was able to inhibit GBM cell proliferation and arrest cell cycle progression in the S phase in a synergistic mechanism. Moreover, suppression of SEPT9 and SEPT2 decreased the GBM cell invasive capability and significantly impaired the growth of glioma xenografts in nude mice. Furthermore, the decrease in GBM cell growth caused by SEPT9 and SEPT2 RNAi appears to involve two parallel signaling pathway including the p53/p21 axis and MEK/ERK activation. Together, our integration of multi-omics analysis has revealed previously unrecognized synergistic role of SEPT9 and SEPT2 in GBM, and provided novel insights into the targeted therapy of GBM.

The requirement of SEPT2 and SEPT7 for migration and invasion in human breast cancer via MEK/ERK activation

Septins are a novel class of GTP-binding cytoskeletal proteins evolutionarily conserved from yeast to mammals and have now been found to play a contributing role in a broad range of tumor types. However, their functional importance in breast cancer remains largely unclear. Here, we demonstrated that pharmaceutical inhibition of global septin dynamics would greatly suppress proliferation, migration and invasiveness in breast cancer cell lines. We then examined the expression and subcellular distribution of the selected septins SEPT2 and SEPT7 in breast cancer cells, revealing a rather variable localization of the two proteins with cell cycle progression. To determine the role of both septins in mediating malignant behavior of cancer cells, we used RNA silencing to specifically deplete endogenous SEPT2 or SEPT7 in highly invasive breast cancer cell line MDA-MB-231. Our findings showed that SEPT2/7 depletion had virtually identical inhibitory effects on cellular proliferation, apoptosis, migration and invasion. Moreover, the opposite performance in migration and invasion was observed after enforced expression of SEPT2/7 in the same cell line. We further demonstrated MEK/ERK activation, but not other MAPKs and AKT, was positively correlated with the protein levels of SEPT2 and SEPT7. Additionally, in SEPT2/7-overexpressing cells, the MEK specific inhibitor U0126 was able to correct the high active status of MEK/ERK while normalizing the increased invasive behaviors of these cells. Taken together, these results strongly suggest that SEPT2 and SEPT7 are involved in breast carcinogenesis and may serve as valuable therapeutic targets for breast cancer.

Proteomic analysis of the soil filamentous fungus Aspergillus nidulans exposed to a Roundup formulation at a dose causing no macroscopic effect: a functional study

Roundup® is a glyphosate-based herbicide (GBH) used worldwide both in agriculture and private gardens. Thus, it constitutes a substantial source of environmental contaminations, especially for water and soil, and may impact a number of non-target organisms essential for ecosystem balance. The soil filamentous fungus Aspergillus nidulans has been shown to be highly affected by a commercial formulation of Roundup® (R450), containing 450 g/L of glyphosate (GLY), at doses far below recommended agricultural application rate. In the present study, we used two-dimensional gel electrophoresis combined to mass spectrometry to analyze proteomic pattern changes in A. nidulans exposed to R450 at a dose corresponding to the no-observed-adverse-effect level (NOAEL) for macroscopic parameters (31.5 mg/L GLY among adjuvants). Comparative analysis revealed a total of 82 differentially expressed proteins between control and R450-treated samples, and 85% of them (70) were unambiguously identified. Their molecular functions were mainly assigned to cell detoxification and stress response (16%), protein synthesis (14%), amino acid metabolism (13%), glycolysis/gluconeogenesis/glycerol metabolism/pentose phosphate pathway (13%) and Krebs TCA cycle/acetyl-CoA synthesis/ATP metabolism (10%). These results bring new insights into the understanding of the toxicity induced by higher doses of this herbicide in the soil model organism A. nidulans. To our knowledge, this study represents the first evidence of protein expression modulation and, thus, possible metabolic disturbance, in response to an herbicide treatment at a dose that does not cause any visible effect. These data are likely to challenge the concept of "substantial equivalence" when applied to herbicide-tolerant plants.

Kinesin superfamily: roles in breast cancer, patient prognosis and therapeutics

Breast cancer pathobiology is known to be influenced by the differential expression of a group of proteins called the kinesin superfamily (KIFs), which is instrumental in the intracellular transport of chromosomes along microtubules during mitosis. During cellular division, kinesins are strictly regulated through temporal synthesis so that they are present only when needed. However, their misregulation may contribute to uncontrolled cell growth owing to premature sister chromatid separation, highlighting their importance in cancer. This review covers the functions of kinesins in normal and breast cancer cells, the use of kinesins for breast cancer patient prognosis, and the targeting of these molecules for therapeutics. A better understanding of KIF proteins may be pivotal to improved disease outcomes for breast cancer patients.

Septin Mutations in Human Cancers

Septins are GTP-binding proteins that are evolutionarily and structurally related to the RAS oncogenes. Septin expression levels are altered in many cancers and new advances point to how abnormal septin expression may contribute to the progression of cancer. In contrast to the RAS GTPases, which are frequently mutated and actively promote tumorigenesis, little is known about the occurrence and role of septin mutations in human cancers. Here, we review septin missense mutations that are currently in the Catalog of Somatic Mutations in Cancer (COSMIC) database. The majority of septin mutations occur in tumors of the large intestine, skin, endometrium and stomach. Over 25% of the annotated mutations in SEPT2, SEPT4, and SEPT9 belong to large intestine tumors. From all septins, SEPT9 and SEPT14 exhibit the highest mutation frequencies in skin, stomach and large intestine cancers. While septin mutations occur with frequencies lower than 3%, recurring mutations in several invariant and highly conserved amino acids are found across different septin paralogs and tumor types. Interestingly, a significant number of these mutations occur in the GTP-binding pocket and septin dimerization interfaces. Future studies may determine how these somatic mutations affect septin structure and function, whether they contribute to the progression of specific cancers and if they could serve as tumor-specific biomarkers.

Cancer-Related Functions and Subcellular Localizations of Septins

Since the initial discovery of septin family GTPases, the understanding of their molecular organization and cellular roles keeps being refined. Septins have been involved in many physiological processes and the misregulation of specific septin gene expression has been implicated in diverse human pathologies, including neurological disorders and cancer. In this minireview, we focus on the importance of the subunit composition and subcellular localization of septins relevant to tumor initiation, progression, and metastasis. We especially underline the importance of septin polymer composition and of their association with the plasma membrane, actin, or microtubules in cell functions involved in cancer and in resistance to cancer therapies. Through their scaffolding role, their function in membrane compartmentalization or through their protective function against protein degradation, septins also emerge as critical organizers of membrane-associated proteins and of signaling pathways implicated in cancer-associated angiogenesis, apoptosis, polarity, migration, proliferation, and in metastasis. Also, the question as to which of the free monomers, hetero-oligomers, or filaments is the functional form of mammalian septins is raised and the control over their spatial and temporal localization is discussed. The increasing amount of crosstalks identified between septins and cellular signaling mediators reinforces the exciting possibility that septins could be new targets in anti-cancer therapies or in therapeutic strategies to limit drug resistance.

Septin cooperation with tubulin polyglutamylation contributes to cancer cell adaptation to taxanes

The mechanisms of cancer cell adaptation to the anti-microtubule agents of the taxane family are multifaceted and still poorly understood. Here, in a model of breast cancer cells which display amplified microtubule dynamics to resist Taxol^®, we provide evidence that septin filaments containing high levels of SEPT9_i1 bind to microtubules in a way that requires tubulin long chain polyglutamylation. Reciprocally, septin filaments provide a scaffold for elongating and trimming polyglutamylation enzymes to finely tune the glutamate side-chain length on microtubules to an optimal level. We also demonstrate that tubulin retyrosination and/or a high level of tyrosinated tubulin is crucial to allow the interplay between septins and polyglutamylation on microtubules and that together, these modifications result in an enhanced CLIP-170 and MCAK recruitment to microtubules. Finally, the inhibition of tubulin retyrosination, septins, tubulin long chain polyglutamylation or of both CLIP-170 and MCAK allows the restoration of cell sensitivity to taxanes, providing evidence for a new integrated mechanism of resistance.

Methylation of the SEPT9_v2 promoter as a novel marker for the detection of circulating tumor DNA in breast cancer patients

The aim of the present study was to evaluate the promoter methylation status of SEPT9_v2 in breast cancer and to detect this methylated gene in circulating tumor DNA (ctDNA) in plasma. Bisulfite sequencing was performed with a next generation sequencer. Methylation of the SEPT9_v2 promoter was found in 67% (8/12) of breast cancer cell lines and 53% (10/19) of breast tumor tissue, but not in normal breast tissue (0/19). A clear inverse correlation was observed between the expression of SEPT9_v2 mRNA and the methylation index (MI) both in cell lines and breast cancer tissues. The MI of SEPT9_v2 was significantly higher in non-basal subtype of breast cancer (13.0%, n=84) than in basal subtype (3.0%, n=23) (P<0.0001). Methylated SEPT9_v2 ctDNA in plasma was detected in 11% (9/82) of primary breast cancer patients and 52% (26/50) of metastatic breast cancer patients, but not in the healthy controls (0/51). These results indicate that SEPT9_v2 promoter hypermethylation, which silences the expression of SEPT9_v2 mRNA, is observed in a significant proportion of breast tumors, and that methylated SEPT9_v2 may serve as a novel tumor marker for breast cancer.

Alterations of the cytoskeleton in human cells in space proved by life-cell imaging

Microgravity induces changes in the cytoskeleton. This might have an impact on cells and organs of humans in space. Unfortunately, studies of cytoskeletal changes in microgravity reported so far are obligatorily based on the analysis of fixed cells exposed to microgravity during a parabolic flight campaign (PFC). This study focuses on the development of a compact fluorescence microscope (FLUMIAS) for fast live-cell imaging under real microgravity. It demonstrates the application of the instrument for on-board analysis of cytoskeletal changes in FTC-133 cancer cells expressing the Lifeact-GFP marker protein for the visualization of F-actin during the 24^th DLR PFC and TEXUS 52 rocket mission. Although vibration is an inevitable part of parabolic flight maneuvers, we successfully for the first time report life-cell cytoskeleton imaging during microgravity, and gene expression analysis after the 31^st parabola showing a clear up-regulation of cytoskeletal genes. Notably, during the rocket flight the FLUMIAS microscope reveals significant alterations of the cytoskeleton related to microgravity. Our findings clearly demonstrate the applicability of the FLUMIAS microscope for life-cell imaging during microgravity, rendering it an important technological advance in live-cell imaging when dissecting protein localization.

Copper (II) and 2,2'-bipyridine complexation improves chemopreventive effects of naringenin against breast tumor cells

Cancer is the second leading cause of death worldwide and there is epidemiological evidence that demonstrates this tendency is emerging. Naringenin (NGEN) is a trihydroxyflavanone that shows various biological effects such as antioxidant, anticancer, anti-inflammatory, and antiviral activities. It belongs to flavanone class, which represents flavonoids with a C6-C3-C6 skeleton. Flavonoids do not exhibit sufficient activity to be used for chemotherapy, however they can be chemically modified by complexation with metals such as copper (Cu) (II) for instance, in order to be applied for adjuvant therapy. This study investigated the effects of Cu(II) and 2,2′-bipyridine complexation with naringenin on MDA-MB-231 cells. We demonstrated that naringenin complexed with Cu(II) and 2,2′-bipyridine (NGENCuB) was more efficient inhibiting colony formation, proliferation and migration of MDA-MB-231 tumor cells, than naringenin (NGEN) itself. Furthermore, we verified that NGENCuB was more effective than NGEN inhibiting pro-MMP9 activity by zymography assays. Finally, through flow cytometry, we showed that NGENCuB is more efficient than NGEN inducing apoptosis in MDA-MB-231 cells. These results were confirmed by gene expression analysis in real time PCR. We observed that NGENCuB upregulated the expression of pro-apoptotic gene caspase-9, but did not change the expression of caspase-8 or anti-apoptotic gene Bcl-2. There are only few works investigating the effects of Cu(II) complexation with naringenin on tumor cells. To the best of our knowledge, this is the first work describing the effects of Cu(II) complexation of a flavonoid on MDA-MB-231 breast tumor cells.

Immunization using GroEL decreases Clostridium difficile intestinal colonization

Clostridium difficile is a pathogen which is responsible for diarrhea and colitis, particularly after treatment with antibiotics. Clinical signs are mainly due to two toxins, TcdA and TcdB. However, the first step of pathogenesis is the colonization process. We evaluated C. difficile surface proteins as vaccine antigens in the hamster model to prevent intestinal colonization. This vaccination induced a partial protection of hamsters against death after a C. difficile challenge. A proteomic analysis of animal sera allowed us to identify proteins which could be responsible for the protection observed. Among these proteins, we identified the GroEL heat shock protein. To confirm the role of the specific GroEL antibodies in the delayed C. difficile colonization of hamsters, we performed an immunization assay in a mouse model. After intranasal immunization with the recombinant protein GroEL, we observed a lower C. difficile intestinal colonization in the immunized group as compared to the control group.

High throughput screening of natural products for anti-mitotic effects in MDA-MB-231 human breast carcinoma cells

Some of the most effective anti-mitotic microtubule-binding agents, such as paclitaxel (Taxus brevifolia) were originally discovered through robust National Cancer Institute botanical screenings. In this study, a high-through put microarray format was utilized to screen 897 aqueous extracts of commonly used natural products (0.00015-0.5 mg/mL) relative to paclitaxel for anti-mitotic effects (independent of toxicity) on proliferation of MDA-MB-231 cells. The data obtained showed that less than 1.34 % of the extracts tested showed inhibitory growth (IG50 ) properties <0.0183 mg/mL. The most potent anti-mitotics (independent of toxicity) were Mandrake root (Podophyllum peltatum), Truja twigs (Thuja occidentalis), Colorado desert mistletoe (Phoradendron flavescens), Tou Gu Cao [symbol: see text] Speranskia herb (Speranskia tuberculata), Bentonite clay, Bunge root (Pulsatilla chinensis), Brucea fruit (Brucea javanica), Madder root (Rubia tinctorum), Gallnut of Chinese Sumac (Melaphis chinensis), Elecampane root (Inula Helenium), Yuan Zhi [symbol: see text] root (Polygala tenuifolia), Pagoda Tree fruit (Melia Toosendan), Stone root (Collinsonia Canadensis), and others such as American Witchhazel, Arjun, and Bladderwrack. The strongest tumoricidal herbs identified from amongst the subset evaluated for anti-mitotic properties were wild yam (Dioscorea villosa), beth root (Trillium Pendulum), and alkanet root (Lithospermum canescens). Additional data was obtained on a lesser-recognized herb: (S. tuberculata), which showed growth inhibition on BT-474 (human ductal breast carcinoma) and Ishikawa (human endometrial adenocarcinoma) cells with ability to block replicative DNA synthesis, leading to G2 arrest in MDA-MB-231 cells. In conclusion, these findings present relative potency of anti-mitotic natural plants that are effective against human breast carcinoma MDA-MB-231 cell division.

Purification and differential biological effects of ginger-derived substances on normal and tumor cell lines

This study describes an optimization of [6]-, [8]- and [10]-gingerol isolation and purification in semi-preparative HPLC scale and their anti-proliferative activity. The gingerols purification was carried out in HPLC system using a Luna-C₁₈ and the best mobile phase evaluated was MeOH/H₂O (75:25, v/v). This new methodology for the gingerols isolation was very effective, since considerable amounts (in the range of milligrams) with a good purity degree (∼98%) were achieved in 30 min of chromatographic run. [6]-, [8]- and [10]-Gingerol purified by this methodology inhibited the proliferation of MDA-MB-231 tumor cell line with IC₅₀ of 666.2±134.6 μM, 135.6±22.6 μM and 12.1±0.3 μM, respectively. These substances also inhibited human fibroblasts (HF) cell proliferation, however in concentrations starting from 500 μM. In conclusion, our results demonstrate an optimization of gingerols isolation and their specific anti-proliferative activities against tumor cells, suggesting their use as important models for drug design in an attempt to develop new compounds with fewer side effects when compared to conventional chemotherapy.