Myoferlin regulates cellular lipid metabolism and promotes metastases in triple-negative breast cancer.

Myoferlin is a multiple C2-domain-containing protein that regulates membrane repair, tyrosine kinase receptor function and endocytosis in myoblasts and endothelial cells. Recently it has been reported as overexpressed in several cancers and shown to contribute to proliferation, migration and invasion of cancer cells. We have previously demonstrated that myoferlin regulates epidermal growth factor receptor activity in breast cancer. In the current study, we report a consistent overexpression of myoferlin in triple-negative breast cancer cells (TNBC) over cells originating from other breast cancer subtypes. Using a combination of proteomics, metabolomics and electron microscopy, we demonstrate that myoferlin depletion results in marked alteration of endosomal system and metabolism. Mechanistically, myoferlin depletion caused impaired vesicle traffic that led to a misbalance of saturated/unsaturated fatty acids. This provoked mitochondrial dysfunction in TNBC cells. As a consequence of the major metabolic stress, TNBC cells rapidly triggered AMP activated protein kinase-mediated metabolic reprogramming to glycolysis. This reduced their ability to balance between oxidative phosphorylation and glycolysis, rendering TNBC cells metabolically inflexible, and more sensitive to metabolic drug targeting in vitro. In line with this, our in vivo findings demonstrated a significantly reduced capacity of myoferlin-deficient TNBC cells to metastasise to lungs. The significance of this observation was further supported by clinical data, showing that TNBC patients whose tumors overexpress myoferlin have worst distant metastasis-free and overall survivals. This novel insight into myoferlin function establishes an important link between vesicle traffic, cancer metabolism and progression, offering new diagnostic and therapeutic concepts to develop treatments for TNBC patients.

Mucolytic Agents Can Enhance HER2 Receptor Accessibility for [(89)Zr]Trastuzumab, Improving HER2 Imaging in a Mucin-Overexpressing Breast Cancer Xenograft Mouse Model.

PURPOSE: Binding of trastuzumab to HER2 receptors can be impaired by steric hindrance caused by mucin MUC4. As mucolytic drugs can breakdown disulfide bonds of mucoproteins, we checked if this approach could positively affect zirconium-89-labeled trastuzumab ([(89)Zr]T) binding/uptake. PROCEDURES: The effect of N-acetylcysteine (NAC) and MUC4 knockdown/stimulation on [(89)Zr]T binding/uptake were evaluated in MCF7(HER2-), BT474 and SKBr3(HER2+/MUC4-), and JIMT1(HER2+/MUC4+) cell lines. The results were then validated in SKBR3 and JIMT1 tumor-bearing nude mice with a microPET-CT and ex vivo analysis. RESULTS: Significant increases in [(89)Zr]T binding/uptake were observed in JIMT1 cells following MUC4 knockdown (62.4 ± 6.5%) and exposure to NAC (62.8 ± 19.4%). Compared to controls, mice treated with NAC showed a significant increase in [(89)Zr]T uptake in MUC4 tumors on microPET-CT (SUVmean (18.3 ± 4.7%), SUVmax (41.7 ± 8.4%)) and individual organ counting (37.3 ± 18.3%). In contrast, no significant differences were observed in SKBr3. CONCLUSION: NAC can enhance [(89)Zr]T accumulation and improve the HER2 imaging of MUC4-overexpressing tumors. The potential positive impact on trastuzumab-based treatment deserves further investigation.

Antagonism by exifone, a new cognitive enhancing agent, of the amnesias induced by four benzodiazepines in mice.

Exifone is a novel compound proposed for treating cognitive decline associated with age and shows corrective effects in animal models of memory dysfunction. The present experiments examined the antagonism by exifone of the amnesias induced in mice in a passive avoidance test by four benzodiazepines: bromazepam, diazepam, lorazepam and triazolam. Subsequent experiments investigated the specificity of exifone's antagonism of benzodiazepine-induced amnesia by examining its interaction with the effects of the benzodiazepines in the staircase test (anxiolytic/sedative activity) and the electroshock test (anticonvulsant activity). The results indicated that exifone clearly antagonised the amnesias induced by the four benzodiazepines, but was without intrinsic effects in the staircase or electroshock test and did not antagonise the effects of the benzodiazepines in these two tests. These results suggest that exifone might be useful for decreasing the amnesias induced by commonly used benzodiazepines without affecting their anxiolytic or anticonvulsant activity.

The effects of exifone, a new agent for senile memory disorder, on two models of memory in the mouse.

The effects of exifone (ADLONE), hexahydro-2,3,4,3',4',5'-benzophenone, were tested in two models of memory in the mouse: habituation of exploratory activity and antagonism of amnesia induced by scopolamine in a passive avoidance task. In the first model, mice which had received exifone (128 and 256 mg/kg IP) 30 minutes before a 3 minute exposure to a staircase exploratory test showed a more marked decrease in exploratory activity in the same apparatus 24 hours later (habituation) than a control group indicating improved memory. Similar results were obtained with piracetam (512 mg/kg, IP). In the second model exifone (512 mg/kg PO), administered 60 minutes before both the learning and retention trials of a standard step-through passive avoidance, task partially antagonized the amnesia induced by 10 mg/kg scopolamine IP administered immediately after the learning trial. Similar results were obtained with piracetam (800 mg/kg PO). Taken together these results suggest that exifone facilitates memory function in simple rodent models in a manner consistent with its supposed therapeutic effects in man.

Determination of exifone in human plasma and urine by high-performance liquid chromatography with electrochemical detection.

A high-performance liquid chromatographic method with electrochemical detection was developed for the determination of exifone in human plasma and urine. Exifone was extracted from acidified plasma or neutralized urine with diethyl ether and the evaporated extracts were analysed on a C18 reversed-phase column. The compound was eluted in about 8 min with acetonitrile-0.3 M orthophosphoric acid (15:85, v/v) at a flow-rate of 0.9 ml/min. This method gave accurate and reproducible results; the calibration graphs were linear (r greater than 0.99) over the range of 2.8-360 nmol/l for plasma and 0.18-36 mumol/l for urine, and concentrations as low as 1 nmol/l in plasma could be quantified. These results allowed this assay to be used for determinations in single-dose pharmacokinetic studies.

Psychopharmacological profile of the new cognition enhancing agent exifone in the mouse.

Hexahydro-2,3,4,3',4',5'-benzophenone (exifone, Adlone), a novel compound proposed for treating cognitive dysfunction in geriatric patients, was tested in a battery of standard psychopharmacological tests in the mouse. The results indicated that the compound was non-toxic and induced no signs of overt stimulation or sedation after acute administration of oral doses up to 1024 mg/kg. The compound was devoid of anxiolytic, anticonvulsant or classical neuroleptic activity and did not antagonize the effects of reserpine or a high dose of apomorphine, two tests indicative of classical antidepressant activity. On the other hand, exifone clearly decreased the duration of immobility in the tail suspension test and antagonized the hypothermia induced by a low dose of apomorphine. The compound shortened the duration of barbital induced sleep without affecting the duration of sleep induced by pentobarbital. The effects observed suggest that exifone is not devoid of psychotropic activity and might possess some properties of an atypical antidepressant.