Metformin shows anti-neoplastic properties by inhibition of oxidative phosphorylation and glycolysis in epidermolysis bullosa-associated aggressive cutaneous squamous cell carcinoma

BACKGROUND

While most cutaneous squamous cell carcinomas (cSCCs) are treatable, certain high-risk cSCCs, such as those in recessive dystrophic epidermolysis bullosa (RDEB) patients, are particularly aggressive. Owing to repeated wounding, inflammation and unproductive healing, RDEB patients have a 68% cumulative risk of developing life-threatening cSCCs by the age of 35, and a 70% risk of death by the age of 45. Despite aggressive treatment, cSCC represents the leading cause of premature mortality in these patients, highlighting an unmet clinical need. Increasing evidence points to a role of altered metabolism in the initiation and maintenance of cSCC, making metabolism a potential therapeutic target.

OBJECTIVES

We sought to determine the feasibility of targeting tumour cell energetics as a strategy to selectively hinder the growth advantage of aggressive cSCC.

METHODS

We evaluated the cell energetics profiles of RDEB-SCC cells by analysing available gene expression data against multiple gene signatures and single-gene targets linked to metabolic reprogramming. Additionally, we employed real-time metabolic profiling to measure glycolysis and respiration in these cells. Furthermore, we investigated the anti-neoplastic properties of the metformin against human and murine high-risk cSCCs in vitro and in vivo.

RESULTS

Gene expression analyses highlighted a divergence in cell energetics profiles between RDEB-SCC and non-malignant RDEB keratinocytes, with tumour cells demonstrating enhanced respiration and glycolysis scores. Real-time metabolic profiling supported these data and additionally highlighted a metabolic plasticity of RDEB-SCC cells. Against this background, metformin exerted an anti-neoplastic potential by hampering both respiration and glycolysis, and by inhibiting proliferation in vitro. Metformin treatment in an analogous model of fast-growing murine cSCC resulted in delayed tumour onset and slower tumour growth, translating to a 29% increase in median overall survival.

CONCLUSIONS

Our data indicate that metformin exerts anti-neoplastic properties in aggressive cSCCs that exhibit high-risk features by interfering with respiration and glycolytic processes.

An ex vivo RNA trans-splicing strategy to correct human generalized severe epidermolysis bullosa simplex

Background

Generalized severe epidermolysis bullosa simplex (EBS‐gen sev) is a genetic blistering skin disease in which autosomal dominant mutations in either the keratin KRT5 or KRT14 genes lead to impaired function of the intermediate filament cytoskeleton in the basal epidermis. Here we present an ex vivo RNA trans‐splicing‐based therapeutic approach to correct the phenotype.

Objectives

To correct a mutation within exon 1 of the KRT14 gene, using a 5′‐trans‐splicing approach, where any mutation within the first seven exons could be replaced by a single therapeutic molecule.

Methods

A therapeutic RNA trans‐splicing molecule containing wild‐type exons 1–7 was stably transduced into an EBS patient‐derived keratinocyte line. Trans‐splicing was confirmed via reverse‐transcriptase polymerase chain reaction, Western blotting and immunofluorescence microscopy. Skin equivalents generated from corrected keratinocytes were grafted onto nude mice and analysed about 8 weeks post‐transplantation for regular epidermal stratification, trans‐splicing‐induced green fluorescent protein expression and blistering.

Results

Transplanted skin equivalents generated from trans‐splicing‐corrected patient keratinocytes showed a stable and blister‐free epidermis. KRT14 correction disrupted EBS‐gen sev‐associated proinflammatory signalling, as shown at the mRNA and protein levels. Disruption of the pathogenic feedback loop in addition to overall downregulation of KRT14 expression highlighted the effect of KRT14 correction on the EBS pathomechanism.

Conclusions

Our data demonstrate that trans‐splicing‐mediated mRNA therapy is an effective method for the correction of dominantly inherited KRT14 mutations at the transcriptional level. This results in the rescue of the EBS‐gen sev phenotype and stabilization of the epidermis in a xenograft mouse model.

What's already known about this topic?

RTM163, described in this study, was previously used in a transient in vitro transfection system, where the ability to correct KRT14 at the mRNA level was demonstrated.

What does this study add?

In this study, we stably transduced RTM163 in a second patient‐derived keratinocyte line.

Successful trans‐splicing was confirmed in this cell line.

The expression of disease‐related marker genes, which are characteristically deregulated in epidermolysis bullosa simplex, were analysed.

For the first time this study showed that RNA trans‐splicing molecule‐transduced patient keratinocytes can differentiate into a phenotypically normal and blister‐free epidermis in a xenograft mouse model.

What is the translational message?

This study shows the feasibility of using spliceosome‐mediated RNA trans‐splicing to generate a stable and blister‐free epidermis in vivo.

Combined with pre‐existing ex vivo gene therapeutic methods, this might be a valid option for future treatments of dominantly inherited genodermatoses.

Linked Comment: Bremer and van den Akker. Br J Dermatol 2019; 180:17–19.

Klinische, ultrasonographische, röntgenologische und endoskopische Befunde sowie Therapiemaßnahmen bei 16 Rindern mit retropharyngealen Abszessen

Ziel dieser retrospektiven Arbeit war, die klinischen, ultrasonographischen, röntgenologischen und endoskopischen Befunde sowie die Behandlung von 16 Rindern mit retropharyngealen Abszessen zu beschreiben. Ergebnisse: Klinisch ließen sich Stenosegeräusche, Umfangsvermehrungen im kranialen Halsbereich, Dyspnoe sowie Husten feststellen. Die ultrasonographische Untersuchung zeigte bei allen Tieren die für Abszesse charakteristischen rundlichen Strukturen mit echogenem Inhalt. Röntgenologisch konnte bei allen Rindern eine Verschattung im Bereich des Pharynxdaches und fallweise eine Gasansammlung über einem Flüssigkeitsspiegel dargestellt werden. Mit dem Endoskop waren bei 13 von 15 untersuchten Tieren Schwellungen im Pharynxdach, bei dreien auch Fistelkanäle zu sehen. Drei der 16 Rinder wurden wegen zusätzlicher Erkrankungen ohne Therapieversuch geschlachtet. Bei 9 Tieren erfolgte eine Operation, bei 4 Tieren eine konservative Behandlung. Insgesamt 12 Tiere konnten langfristig geheilt werden. Schlussfolgerung und klinische Relevanz: Die Arbeit zeigt die Bedeutung der sorgfältigen diagnostischen Abklärung solcher Fälle hinsichtlich des Heilungserfolges. Wird die Diagnose früh und korrekt gestellt, ergibt sich bei Behandlung retropharyngealer Abszesse eine gute Prognose.

A tissue engineering approach to meniscus regeneration in a sheep model

OBJECTIVE

Regeneration of the meniscal tissue occurs to a limited extent, and the loss of meniscal tissue leads to osteoarthritis. A new biomaterial consisting of hyaluronic acid and polycaprolactone was used as a meniscus substitute in sheep to evaluate the properties of the implant material with regard to size, biomechanical stability, tissue ingrowth, and integration.

METHODS

Eight sheep (right stifle joints) were treated with three total and three partial meniscus replacements while two meniscectomies served as empty controls. The animals were euthanized after 6 weeks. The specimens were assessed by gross inspection and histology, and compared with the nonoperated left joints.

RESULTS

The surgical technique was found to be feasible. The implants remained in position, did not tear, and showed excellent tissue ingrowth to the capsule. Tissue integration was also observed between the original meniscus and the implant. However, graft compression and extrusion occurred. The histological investigation revealed tissue formation, cellular infiltration and vascularization. Cartilage degeneration was more severe in the operated joints.

CONCLUSION

The present study shows promising results concerning the qualities of this biomaterial with regard to implantation technique, stability and tissue ingrowth.

Biochemische Parameter und Vitaminstatus von Milchkühen während des Heilungsverlaufs von Sohlengeschwüren

Bei 24 Kühen mit leichtgradigen Rusterholz-Sohlengeschwüren wurde unter kontrollierten Bedingungen über einen Zeitraum von 50 Tagen der Heilungsverlauf überprüft. Während der Heilungsphase kam es bei 14 Tieren zu einer mikroskopisch sichtbaren Verbesserung der Hornstruktur (Gruppe A). Bei 10 Tieren konnte keine Verbesserung und zum Teil sogar eine Verschlechterung der Hornqualität nachgewiesen werden (Gruppe B). Die Resultate der blutchemischen Untersuchungen am Tag 0, 10, 20, 30, 40 und 50 wurden zwischen Gruppe A und B verglichen.

Die durchschnittlichen Serumenzymaktivitäten der GLDH, ALT, AP, γ-GT und LDH lagen bei den Kühen der Gruppe B zu jedem Messpunkt höher als bei den Tieren der Gruppe A. Bei der AP und der GLDH war der Unterschied signifikant. Die Tiere mit einer Verschlechterung der Hornqualität (Gruppe B) zeigten durchschnittlich signifikant niedrigere Vitamin-A-Konzentrationen als diejenigen mit einer Verbesserung (Gruppe A). Die Ergebnisse bestätigen den bekannten Einfluss von Vitamin A auf die Wundheilung. Der unterschiedliche Verlauf der zur Diagnose von Parenchymschäden der Leber verwendeten Enzyme GLDH, ALT, AP, γ-GT und LDH weist darauf hin, dass eine subklinische Einschränkung der Leberfunktion bei Kühen zu einer Beeinträchtigung der Heilung von Sohlengeschwüren beitragen kann.

Ultrasonographic findings in cows with dilatation, torsion and retroflexion of the caecum

Thirty cows with caecal dilatation underwent clinical and ultrasonographic examinations, followed by a right flank laparotomy and surgical correction. The intraoperative findings were compared with the results of the ultrasonographic examination. The appearance, position, dimensions, diameter and nature of the contents of the caecum and proximal and spiral ansa of the colon were determined with a 3.5 MHz linear transducer. The wall of the proximal ansa of the colon and of the dilated caecum closest to the abdominal wall was visible in all the cows and appeared as an echogenic semicircular line immediately adjacent to the peritoneum. The contents of the caecum and of the proximal and spiral ansa of the colon were not visible in 21, 25 and 25 cows, respectively, owing to gas. In the remaining cows, the contents were hypoechogenic to echogenic in appearance. In all of the cows, the dilated caecum was imaged from the right abdominal wall at the level of the tuber coxae. The caecum was imaged from the 12th, 11th and 10th intercostal spaces in 11, five and three cows, respectively. The caecum and proximal ansa of the colon were situated immediately adjacent to the right abdominal wall in 28 cows, but in the other two cows parts of these structures were pushed away from the abdominal wall by the liver or gall bladder. The diameter of the caecum, measured at various sites varied from 7.0 to 25.0 cm. Caecal dilatation was diagnosed on the basis of the results of rectal examinations in 28 of the cows, but in all 30 cows on the basis of the results of the ultrasonographic examinations. Dilatation and caudal displacement of the caecum were diagnosed in 18 cows; dilatation and cranioventral retroflexion of the caecum were diagnosed in six cows, and dilatation and craniodorsal retroflexion of the caecum were diagnosed in two cows. In the four other cows, the direction of the retroflexed caecum could not be determined. The diagnosis of caecal dilatation based on the ultrasonographic findings was confirmed in all the cows during exploratory laparotomy. The results of ultrasonography and exploratory surgery with regard to the position of the dilated and sometimes retroflexed or twisted caecum were in complete agreement in 18 cases, in partial agreement in eight cases, but in four cases did not agree.

Effect of therapeutic dietary biotin on the healing of uncomplicated sole ulcers in dairy cattle--a double blinded controlled study

The objective of this study was to investigate the influence of orally administered biotin on the healing of uncomplicated sole ulcers in dairy cattle. In a double-blind controlled study, 24 dairy cows with a mild, uncomplicated sole ulcer on a lateral hind claw were given either 40 mg biotin per day or a placebo feed over a period of 50 days. An orthopaedic shoe was fitted to the medial claw of the affected foot. The healing process was assessed clinically and by histological examination of horn samples. In the biotin-treated animals, the newly formed epidermis covering the sole ulcers was found to be of significantly better histological quality after 50 days than at the start of the study. The significant improvement in histological horn quality found in the biotin-treated animals suggests that biotin exerts a positive influence on the healing of sole ulcers, however the study period of 50 days appears to have been too short to permit macroscopic detection of the improvement in horn quality.

[Implantation of synthetic mesh for the closing of abdominal wall ruptures in the ventral flank of cows: a retrospective study of 16 cases]

In this paper the technique and long-term results for abdominal wall ruptures in the ventral flank are described in 16 cows that underwent surgery between January 1990 and October 1999. Most injuries were caused by a horn of another cow. In three cases the rupture was repaired longer than 6 weeks after traumatic injury. The other defects were treated surgically 6.4 (0-25) days after they occurred. The muscle defects were closed layer by layer with simple continuous sutures (polyglactin 910, 6 metric) under general anesthesia in lateral recumbency and the sutured defect was reinforced with a synthetic mesh (polyester or polyglactin 910) fixed to the outside of the external oblique abdominal muscle. The most frequent postoperative complication was subcutaneous seroma. It was treated successfully by incision and drainage. All patients were released 11.6 +/- 5.5 (6-23) days after surgery. A telephone survey 53 +/- 26 (7-106) months after surgery revealed that the patients had an average survival time of 30 (2-104) months, had born one to seven calves without any complications and that only one cow had had an unsatisfactory milk yield. One cow had to be slaughtered 2 months after surgery because of a relapse. Synthetic mesh was used successfully to close the defect in 15 animals. The functional as well as the cosmetic result of the described operation was good to excellent.

Strangulation of the duodenum by the uterus during late pregnancy in two cows

Two Swiss Braunvieh cows in late pregnancy underwent surgery because of a rare form of ileus due to strangulation of the duodenum at its caudal flexure by the gravid uterus. The whole uterus had passed through a gap between the mesoduodenum and duodenum and with increasing weight had led to strangulation of the duodenum. This was possible since the mesoduodenum and both walls of the greater omentum adjacent to its caudal edge were not connected with the duodenum, probably due to a congenital inhibitory malformation. A transsection and an end-to-end anastomosis of the duodenum were necessary in both cases since it was impossible to retract the gravid uterus through the defect. Postoperative recovering was uneventful in both cows, which were discharged after seven and five days respectively and calved normally about two months later.

Imaging findings in a cow with a retropharyngeally displaced magnet

This report describes the ultrasonographic and radiographic findings and the treatment of a Swiss Brown cow with a retropharyngeal abscess caused by improper administration of a magnet.

In vitro tests overestimate in vivo neutralizing capacity of antacids in presence of food

The neutralizing capacity of two antacids (Alucol = A, Syntrogel = S), differing both in their composition and theoretical neutralizing capacity, was evaluated in vitro and in vivo. In vitro at pH 3.5, 1 ml of A or S neutralizes 3.9 and 1.6 meq of acid, respectively, in an aqueous solution. When tested in vivo in the absence of food during near maximal acid secretion, induced by impromidine, 60 ml of either A or S reduced the 4-hr mean H+ activity by 83% and 65%, respectively. In contrast, the reduction of the 12-hr H+ activity observed after repeated administration of 30-60 ml of A or S at the end of the postprandial hour failed to reach significance with both preparations. This suggests that interaction with food produces a considerable loss of in vivo antacid neutralizing capacity, not quantitatively predictable from in vitro tests.