LEF1 supports metastatic brain colonization by regulating glutathione metabolism and increasing ROS resistance in breast cancer.

More than half of all brain metastases show infiltrating rather than displacing growth at the macro-metastasis/organ parenchyma interface (MMPI), a finding associated with shorter survival. The lymphoid enhancer-binding factor-1 (LEF1) is an epithelial-mesenchymal transition (EMT) transcription factor that is commonly overexpressed in brain-colonizing cancer cells. Here, we overexpressed LEF1 in an in vivo breast cancer brain colonization model. It shortened survival, albeit without engaging EMT at the MMPI. By differential proteome analysis, we identified a novel function of LEF1 as a regulator of the glutathione (GSH) system, the principal cellular redox buffer. LEF1 overexpression also conferred resistance against therapeutic GSH depletion during brain colonization and improved management of intracellular ROS. We conclude that besides EMT, LEF1 facilitates metastasis by improving the antioxidative capacity of epithelial breast cancer cells, in particular during colonization of the brain parenchyma.

PI3K: A master regulator of brain metastasis-promoting macrophages/microglia.

Mutations and activation of the PI3K signaling pathway in breast cancer cells have been linked to brain metastases. However, here we describe that in some breast cancer brain metastases samples the protein expression of PI3K signaling components is restricted to the metastatic microenvironment. In contrast to the therapeutic effects of PI3K inhibition on the breast cancer cells, the reaction of the brain microenvironment is less understood. Therefore we aimed to quantify the PI3K pathway activity in breast cancer brain metastasis and investigate the effects of PI3K inhibition on the central nervous system (CNS) microenvironment. First, to systematically quantify the PI3K pathway activity in breast cancer brain metastases, we performed a prospective biomarker study using a reverse phase protein array (RPPA). The majority, namely 30 out of 48 (62.5%) brain metastatic tissues examined, revealed high PI3K signaling activity that was associated with a median overall survival (OS) of 9.41 months, while that of patients, whose brain metastases showed only moderate or low PI3K activity, amounted to only 1.93 and 6.71 months, respectively. Second, we identified PI3K as a master regulator of metastasis-promoting macrophages/microglia during CNS colonization; and treatment with buparlisib (BKM120), a pan-PI3K Class I inhibitor with a good blood-brain-barrier penetrance, reduced their metastasis-promoting features. In conclusion, PI3K signaling is active in the majority of breast cancer brain metastases. Since PI3K inhibition does not only affect the metastatic cells but also re-educates the metastasis-promoting macrophages/microglia, PI3K inhibition may hold considerable promise in the treatment of brain metastasis and the respective microenvironment.

Carcinoma cells misuse the host tissue damage response to invade the brain.

The metastatic colonization of the brain by carcinoma cells is still barely understood, in particular when considering interactions with the host tissue. The colonization comes with a substantial destruction of the surrounding host tissue. This leads to activation of damage responses by resident innate immune cells to protect, repair, and organize the wound healing, but may distract from tumoricidal actions. We recently demonstrated that microglia, innate immune cells of the CNS, assist carcinoma cell invasion. Here we report that this is a fatal side effect of a physiological damage response of the brain tissue. In a brain slice coculture model, contact with both benign and malignant epithelial cells induced a response by microglia and astrocytes comparable to that seen at the interface of human cerebral metastases. While the glial damage response intended to protect the brain from intrusion of benign epithelial cells by inducing apoptosis, it proved ineffective against various malignant cell types. They did not undergo apoptosis and actually exploited the local tissue reaction to invade instead. Gene expression and functional analyses revealed that the C-X-C chemokine receptor type 4 (CXCR4) and WNT signaling were involved in this process. Furthermore, CXCR4-regulated microglia were recruited to sites of brain injury in a zebrafish model and CXCR4 was expressed in human stroke patients, suggesting a conserved role in damage responses to various types of brain injuries. Together, our findings point to a detrimental misuse of the glial damage response program by carcinoma cells resistant to glia-induced apoptosis.

Short-term impact of the COVID-19 pandemic on patients with a chronic pain disorder.

ABSTRACT: The current Covid-19 pandemic has already had a definite impact on the daily life of many people worldwide. It has been proposed that people with preexisting medical conditions will be harder hit by the pandemic and the subsequent measures to contain the spread of the disease. In this questionnaire-based, observational study, we aimed to assess the impact of the pandemic on patients with a chronic pain disorder, who are treated at a tertiary multidisciplinary pain center.Participants rated the impact of the pandemic on their chronic pain disorder using a self-designed questionnaire. Also, participants filled out the regular follow-up questionnaire to assess a chronic pain disorder measuring among other parameters pain intensity, symptoms of depression, anxiety, stress, and pain-related quality of life.Of 136 eligible patients who presented to our pain center between May 5th and July 17th, 112 agreed to participate in the study (82.4%). Eighty two participants (73.2%) reported a deterioration of the pain disorder using the self-designed questionnaire. The more robust parameters of the regular follow-up questionnaire showed no relevant changes compared to data collected before the pandemic. We were not able to detect any demographic and medical parameters that were clinically relevantly associated with a higher impact of the pandemic.We conclude that a chronic pain disorder is a relatively stable disease that does not change significantly due to external factors, like the Covid-19 pandemic, even if the subjective impact is perceived to be high.

Microglia promote colonization of brain tissue by breast cancer cells in a Wnt-dependent way.

Although there is increasing evidence that blood-derived macrophages support tumor progression, it is still unclear whether specialized resident macrophages, such as brain microglia, also play a prominent role in metastasis formation. Here, we show that microglia enhance invasion and colonization of brain tissue by breast cancer cells, serving both as active transporters and guiding rails. This is antagonized by inactivation of microglia as well as by the Wnt inhibitor Dickkopf-2. Proinvasive microglia demonstrate altered morphology, but neither upregulation of M2-like cytokines nor differential gene expression. Bacterial lipopolysacharide shifts tumor-educated microglia into a classical M1 phenotype, reduces their proinvasive function, and unmasks inflammatory and Wnt signaling as the most strongly regulated pathways. Histological findings in human brain metastases underline the significance of these results. In conclusion, microglia are critical for the successful colonization of the brain by epithelial cancer cells, suggesting inhibition of proinvasive microglia as a promising antimetastatic strategy.

Intra-osseous ultrasound for pedicle screw positioning in the subaxial cervical spine: an experimental study.

BACKGROUND: In contrast to other regions of the human spine, dorsal fixation with rods and pedicle screws is comparatively rarely performed in the cervical spine. Although this technique provides a higher mechanical strength than the more frequently used lateral mass screws, many surgeons fear the relatively high rate of misplacements. This higher incidence is mainly due to the complex vertebral anatomy in this spinal segment. For correct screw placement, the availability of an immediate and efficient intra-operative imaging tool to ascertain the accuracy of the pedicle screw hole position would be beneficial. We have previously investigated the usefulness of an intraspinal, specifically, intra-osseous ultrasound technique in the lumbar spine. In this study its accuracy as a means of controlling intrapedicular screw hole positioning has been evaluated in the cervical spine. METHODS: An endovascular ultrasound transducer was used for the intra-luminal scanning of 54 pedicle screw holes in cadaveric human spine specimens. Twenty-three of these had been intentionally misplaced (cortex breached). The resulting image files were assessed by three investigators blinded to both the procedure and the corresponding CT findings. FINDINGS: The investigators differentiated correctly between adequately and poorly placed pedicle screw holes in 96% of cases. False negatives and false positives both occurred in no more than 1.8% of cases. CONCLUSIONS: Intrapedicular ultrasonography of pedicle screw holes in the cervical spine is a promising technique for the intra-operative assessment of bore hole placement and may increase operative safety and postoperative outcome in posterior cervical fusion surgery.

5-Aminolevulinic Acid Fluorescence Indicates Perilesional Brain Infiltration in Brain Metastases.

BACKGROUND: In glioma surgery, 5-aminolevulinic acid (5-ALA) fluorescence reflects tumor infiltration, and fluorescence-assisted resection correlates with higher removal rates and improved progression-free survival. Recent studies report that a sizable proportion of brain metastases exhibit peritumoral infiltration on the cellular level. There is little information regarding whether 5-ALA is useful to guide surgery in the peritumoral zone in metastases. The aim of this study was to assess histologically whether 5-ALA fluorescence accurately reflects metastatic brain infiltration. METHODS AND MATERIALS: Fluorescence-assisted tumor resection was performed in 27 patients with brain metastases. Patients received 20 mg/kg 5-ALA 3 hours before anesthesia. After resection, biopsy specimens of the surrounding parenchyma were analyzed for 5-ALA fluorescence and histologic evidence of infiltrating tumor cells. The correlation between 5-ALA positivity and immunohistochemical evidence of tumor in the peritumoral zone was also assessed. RESULTS: Of 27 metastases, 23 (85%) were 5-ALA positive. For qualitative tissue analysis, 110 of 125 samples were collected. Metastatic infiltration was present in 49 samples with faint or red fluorescence; 33 samples without fluorescence were tumor-free. The presence of metastatic infiltration correlated with fluorescence (P < 0.001). Tumor infiltration correlated with fluorescence (blue fluorescence 0.09% ± 0.04% and red or faint fluorescence 3.26%; P = 0.003). CONCLUSIONS: Infiltration of surrounding brain tissue is a common finding in brain metastases in selected primary tumors. 5-ALA fluorescence correlates with tumor cell infiltration and might guide more radical resection.

Effect of rosiglitazone treatment on soluble CD40L in patients with type 2 diabetes and coronary artery disease.

BACKGROUND: Interaction of CD40L with its receptor CD40 is critically involved in inflammatory cell activation in atherogenesis. In addition, serum levels of soluble CD40L are elevated in acute coronary syndromes and have been associated with increased cardiovascular risk in healthy subjects, thus making sCD40L an intriguing target to modulate the inflammatory response in the vasculature. PPARgamma-activating thiazolidinediones, novel insulin-sensitizing antidiabetic agents, have recently been shown to exhibit antiinflammatory effects in the vessel wall. To examine whether thiazolidinedione treatment might modulate serum levels of sCD40L in high-risk patients, we performed a randomized, placebo-controlled, single-blinded trial to assess the effect of rosiglitazone on sCD40L levels in patients with type 2 diabetes and coronary artery disease (CAD). METHODS AND RESULTS: Thirty-nine patients with diabetes and angiographically proven CAD were randomized to receive rosiglitazone (4 mg BID) or placebo for 12 weeks. Baseline parameters did not significantly differ between groups. Rosiglitazone treatment, but not placebo, significantly reduced sCD40L serum levels within the first 2 weeks by 8.1% (17.1 to -32.7) (median percentage [interquartile range]; P<0.05 compared with baseline), further decreasing it by 18.4% (-5.0 to -33.1) after 6 weeks (P<0.05 compared with baseline), and by 27.5% (8.2 to -70.5) after 12 weeks (P<0.05 compared with baseline and with 2 weeks of treatment). CONCLUSIONS: Treatment with the PPARgamma-activating thiazolidinedione rosiglitazone reduces sCD40L serum levels in patients with type 2 diabetes and CAD. These data support an antiinflammatory and potentially antiatherogenic effect of thiazolidinediones.

Antidiabetic PPAR gamma-activator rosiglitazone reduces MMP-9 serum levels in type 2 diabetic patients with coronary artery disease.

BACKGROUND: Matrix metalloproteinases (MMPs) are critically involved in the development of unstable plaques. Although arteriosclerotic lesions in patients with diabetes mellitus are more unstable than those of nondiabetic subjects, nothing is known about serum levels of MMPs in these patients or about mechanisms to modulate MMP levels. We investigated MMP levels in diabetic and nondiabetic coronary artery disease (CAD) patients and performed a clinical trial to assess the effect of the PPARgamma-activating, antidiabetic thiazolidinedione rosiglitazone on MMP levels in diabetic CAD patients. METHODS AND RESULTS: In CAD patients, MMP-2, -8, and -9 serum levels were significantly higher in type 2 diabetic subjects compared with age-, sex-, and body mass index-matched nondiabetics. Thirty-nine diabetic patients with CAD were randomized to receive rosiglitazone 4 mg (twice daily) or placebo for 12 weeks. Rosiglitazone treatment, but not placebo, significantly reduced MMP-9 levels already after 2 weeks by -19.6% (-38.3% to 8.6%, P<0.05), and levels remained suppressed until the end of the study. In addition, rosiglitazone significantly decreased serum amyloid A (SAA) and tumor necrosis factor-alpha levels. CONCLUSION: MMP-9 levels are increased in type 2 diabetic patients with CAD, and treatment of these patients with the antidiabetic PPARgamma-activator rosiglitazone significantly reduces MMP-9, tumor necrosis factor-alpha, and SAA serum levels. These data support anti-inflammatory and potential antiatherogenic effects of thiazolidinediones.

Tumor-derived microvesicles mediate human breast cancer invasion through differentially glycosylated EMMPRIN.

Tumor cells secrete not only a variety of soluble factors, but also extracellular vesicles that are known to support the establishment of a favorable tumor niche by influencing the surrounding stroma cells. Here we show that tumor-derived microvesicles (T-MV) also directly influence the tumor cells by enhancing their invasion in a both autologous and heterologous manner. Neither the respective vesicle-free supernatant nor MV from benign mammary cells mediate invasion. Uptake of T-MV is essential for the proinvasive effect. We further identify the highly glycosylated form of the extracellular matrix metalloproteinase inducer (EMMPRIN) as a marker for proinvasive MV. EMMPRIN is also present at high levels on MV from metastatic breast cancer patients in vivo. Anti-EMMPRIN strategies, such as MV deglycosylation, gene knockdown, and specific blocking peptides, inhibit MV-induced invasion. Interestingly, the effect of EMMPRIN-bearing MV is not mediated by matrix metalloproteinases but by activation of the p38/MAPK signaling pathway in the tumor cells. In conclusion, T-MV stimulate cancer cell invasion via a direct feedback mechanism dependent on highly glycosylated EMMPRIN.

The metastatic infiltration at the metastasis/brain parenchyma-interface is very heterogeneous and has a significant impact on survival in a prospective study.

UNLABELLED: The current approach to brain metastases resection is macroscopic removal of metastasis until reaching the glial pseudo-capsule (gross total resection (GTR)). However, autopsy studies demonstrated infiltrating metastatic cells into the parenchyma at the metastasis/brain parenchyma (M/BP)-interface. AIMS/METHODS: To analyze the astrocyte reaction and metastatic infiltration pattern at the M/BP-interface with an organotypic brain slice coculture system. Secondly, to evaluate the significance of infiltrating metastatic tumor cells in a prospective biopsy study. Therefore, after GTR, biopsies were obtained from the brain parenchyma beyond the glial pseudo-capsule and analyzed histomorphologically. RESULTS: The coculture revealed three types of cancer cell infiltration. Interestingly, the astrocyte reaction was significantly different in the coculture with a benign, neuroectodermal-derived cell line. In the prospective biopsy study 58/167 (34.7%) samples revealed infiltrating metastatic cells. Altogether, 25/39 patients (64.1%) had proven to exhibit infiltration in at least one biopsy specimen with significant impact on survival (OS) (3.4 HR; p = 0.009; 2-year OS was 6.6% versus 43.5%). Exceptionally, in the non-infiltrating cohort three patients were long-term survivors. CONCLUSIONS: Metastatic infiltration has a significant impact on prognosis. Secondly, the astrocyte reaction at the M/BP-interface is heterogeneous and supports our previous concept of the organ-specific defense against metastatic (organ-foreign) cells.