HERC5 downregulation in non-small cell lung cancer is associated with altered energy metabolism and metastasis

BACKGROUND

Metastasis is the leading cause of cancer-related death in non-small cell lung cancer (NSCLC) patients. We previously showed that low HERC5 expression predicts early tumor dissemination and a dismal prognosis in NSCLC patients. Here, we performed functional studies to unravel the mechanism underlying the "metastasis-suppressor" effect of HERC5, with a focus on mitochondrial metabolism pathways.

METHODS

We assessed cell proliferation, colony formation potential, anchorage-independent growth, migration, and wound healing in NSCLC cell line models with HERC5 overexpression (OE) or knockout (KO). To study early tumor cell dissemination, we used these cell line models in zebrafish experiments and performed intracardial injections in nude mice. Mass spectrometry (MS) was used to analyze protein changes in whole-cell extracts. Furthermore, electron microscopy (EM) imaging, cellular respiration, glycolytic activity, and lactate production were used to investigate the relationships with mitochondrial energy metabolism pathways.

RESULTS

Using different in vitro NSCLC cell line models, we showed that NSCLC cells with low HERC5 expression had increased malignant and invasive properties. Furthermore, two different in vivo models in zebrafish and a xenograft mouse model showed increased dissemination and metastasis formation (in particular in the brain). Functional enrichment clustering of MS data revealed an increase in mitochondrial proteins in vitro when HERC5 levels were high. Loss of HERC5 leads to an increased Warburg effect, leading to improved adaptation and survival under prolonged inhibition of oxidative phosphorylation.

CONCLUSIONS

Taken together, these results indicate that low HERC5 expression increases the metastatic potential of NSCLC in vitro and in vivo. Furthermore, HERC5-induced proteomic changes influence mitochondrial pathways, ultimately leading to alterations in energy metabolism and demonstrating its role as a new potential metastasis suppressor gene.

Clonality of circulating tumor cells in breast cancer brain metastasis patients

Background

The incidence of brain metastases in breast cancer (BCBM) patients is increasing. These patients have a very poor prognosis, and therefore, identification of blood-based biomarkers, such as circulating tumor cells (CTCs), and understanding the genomic heterogeneity could help to personalize treatment options.

Methods

Both EpCAM-dependent (CellSearch® System) and EpCAM-independent Ficoll-based density centrifugation methods were used to detect CTCs from 57 BCBM patients. DNA from individual CTCs and corresponding primary tumors and brain metastases were analyzed by next-generation sequencing (NGS) in order to evaluate copy number aberrations and single nucleotide variations (SNVs).

Results

CTCs were detected after EpCAM-dependent enrichment in 47.7% of the patients (≥ 5 CTCs/7.5 ml blood in 20.5%). The CTC count was associated with ERBB2 status (p = 0.029) of the primary tumor as well as with the prevalence of bone metastases (p = 0.021). EpCAM-independent enrichment revealed CTCs in 32.6% of the patients, especially among triple-negative breast cancer (TNBC) patients (70.0%). A positive CTC status after enrichment of either method was significantly associated with decreased overall survival time (p < 0.05). Combining the results of both enrichment methods, 63.6% of the patients were classified as CTC positive. In three patients, the matched tumor tissue and single CTCs were analyzed by NGS showing chromosomal aberrations with a high genomic clonality and mutations in pathways potentially important in brain metastasis formation.

Conclusion

The detection of CTCs, regardless of the enrichment method, is of prognostic relevance in BCBM patients and in combination with molecular analysis of CTCs can help defining patients with higher risk of early relapse and suitability for targeted treatment.

Electronic supplementary material

The online version of this article (10.1186/s13058-019-1184-2) contains supplementary material, which is available to authorized users.

Frequency of Circulating Tumor Cells (CTC) in Patients with Brain Metastases: Implications as a Risk Assessment Marker in Oligo-Metastatic Disease

Forty percent of non-small cell lung cancer (NSCLC) patients develop brain metastases, resulting in a dismal prognosis. However, patients in an oligo-metastatic brain disease setting seem to have better outcomes. Here, we investigate the possibility of using circulating tumor cells (CTCs) as biomarkers to differentiate oligo-metastatic patients for better risk assessment. Using the CellSearch® system, few CTCs were detected among NSCLC patients with brain metastases (n = 52, 12.5% ≥ two and 8.9% ≥ five CTC/7.5 mL blood) and especially oligo-metastatic brain patients (n = 34, 5.9%, and 2.9%). Still, thresholds of both ≥ two and ≥ five CTCs were independent prognostic indicators for shorter overall survival time among all of the NSCLC patients (n = 90, two CTC ≥ HR: 1.629, p = 0.024, 95% CI: 1.137⁻6.465 and five CTC ≥ HR: 2.846, p = 0.0304, CI: 1.104⁻7.339), as well as among patients with brain metastases (two CTC ≥ HR: 4.694, p = 0.004, CI: 1.650⁻13.354, and five CTC ≥ HR: 4.963, p = 0.003, CI: 1.752⁻14.061). Also, oligo-brain NSCLC metastatic patients with CTCs had a very poor prognosis (p = 0.019). Similarly, in other tumor entities, only 9.6% of patients with brain metastases (n = 52) had detectable CTCs. Our data indicate that although patients with brain metastases more seldom harbor CTCs, they are still predictive for overall survival, and CTCs might be a useful biomarker to identify oligo-metastatic NSCLC patients who might benefit from a more intense therapy.

Improved Risk Stratification by Circulating Tumor Cell Counts in Pancreatic Cancer

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Characterization of different CTC subpopulations in non-small cell lung cancer

Circulating tumour cells (CTCs) serve as valuable biomarkers. However, EpCAM positive CTCs are less frequently detected in NSCLC patients compared to other epithelial tumours. First, EpCAM protein expression was analysed in primary and metastatic lung cancer tissue. In both groups 21% of the samples were EpCAM negative. Second, the CellSearch system identified 15% of patients (n = 48) as CTC positive whereas a multiplex RT-PCR for PIK3CA, AKT2, TWIST, and ALDH1 following EGFR, HER2 and EpCAM based enrichment detected CTCs in 29% of the patients. Interestingly, 86% of CTC positive patients were found to express ALDH1. Only 11% of the patients were CTC-positive by both techniques. CTC positivity was associated with patient disease state when assessed by the multiplex RT-PCR assay (p = 0.015). Patients harbouring tumours with an altered EGFR genotype were more frequently CTC-positive compared to patients with EGFR wildtype tumours. In subsets of patients, CTCs were found to express genes involved in resistance to therapy such as HER3 and MET. In conclusion, using multiple targets for CTC capture and identification increases the sensitivity of CTC detection in NSCLC patients, which can be explained by the presence of different CTC subtypes with distinct molecular features.

Detection of Circulating Tumor Cells in Non-Small Cell Lung Cancer

Lung cancer is the most common cause of cancer-related deaths that frequently metastasizes prior to disease diagnosis. Circulating tumor cells (CTCs) are found in many different types of epithelial tumors and are of great clinical interest in terms of prognosis and therapy intervention. Here, we present and discuss epithelial cell adhesion molecule-dependent and -independent capture of CTCs in non-small cell lung cancer (NSCLC) and the clinical relevance of CTC detection and characterization. Taking blood samples and analyzing CTCs as "liquid biopsy" might be a far less invasive diagnostic strategy than biopsies of lung tumors or metastases. Moreover, sequential blood sampling allows to study the dynamic changes of tumor cells during therapy, in particular the development of resistant tumor cell clones.

Histological Evaluation of Acute Covering of an Experimental Neural Tube Defect with Biomatrices in Fetal Sheep

OBJECTIVE

The aim of the study was to determine the histological effect on the neural tissue of in utero covering of an experimental neural tube defect in fetal lambs, with the use of two different biomatrices.

MATERIALS AND METHODS

In 23 fetal sheep, surgery was performed at 79 days' gestation. In 19 of these, a neural tube defect was created, while 4 fetuses served as sham-operated controls. In 7 of the 19 operated fetuses the defect was left uncovered. In the remaining 12 animals the defect was covered either with a collagen biomatrix (4 animals), skin (3 animals), or small intestinal submucosa biomatrix (5 animals). The lambs were sacrificed at 1 week of age and histological examination was performed.

RESULTS

All lambs with an uncovered neural tube defect showed histological damage of the spinal cord. In lambs in which the neural tube defect was covered, one half showed a normal architecture of the spinal cord while minor histological damage was present in the other half. Between the three groups in which the defect was covered, the histological outcome was comparable.

CONCLUSIONS

Acute covering of an experimental neural tube defect in fetal lambs prevents severe histological damage to the spinal cord independent of the two biomatrices used in this study.

In utero Repair of an Experimental Neural Tube Defect in a Chronic Sheep Model Using Biomatrices

OBJECTIVE

Persistent exposure of the unprotected spinal cord to amniotic fluid and the uterine wall can lead to progressive damage of neural tissue in case of a myelomeningocele (two-hit hypothesis). The aim of this study was to evaluate whether in utero repair of an experimental neural tube defect in a fetal lamb could protect neural tissue from secondary injury and save neurologic functions after birth.

METHODS

In 19 fetal lambs, a neural tube defect was created at 79 days' gestation. In 12 lambs the defect was covered either with a novel, molecular defined collagen-based biocompatible and biodegradable matrix (UMC) or with a small intestinal submucosa (SIS) biomatrix (Cook) or by closing the skin over the defect.

RESULTS

All lambs with the defect covered showed no or minor neurologic morbidity in contrast to the lambs with the defect uncovered in which major neurologic morbidity was seen.

CONCLUSIONS

These results demonstrate that long-term exposure of the open spinal cord to the intrauterine environment can lead to damage of neural tissue and, consequently loss of neurologic functions and that coverage of the defect can lead to a better neurologic outcome. Furthermore, we could show that a UMC biomatrix and an SIS biomatrix are useful for in utero coverage of a surgically created neural tube defect in our model.

A rabbit model to tissue engineer the bladder

A rabbit model was used for the evaluation of a collagen-based biomatrix of small intestinal submucosa (SIS, COOK) in comparison to a biochemically reconstructed biomatrix for bladder tissue regeneration. Rabbits underwent partial cystectomy and cystoplasty with SIS patch graft or with a biochemically defined collagen biomatrix. The grafts of the regenerated bladder wall were harvested at different intervals and tissue regeneration was evaluated. The results of the SIS and biochemically defined biomatrix grafts were comparable. At harvesting, we found five bladder stones and encrustation of the biomatrix in 21/56 animals. No stone formation was observed in the control group. The results of the molecularly defined biomatrix are thus far comparable to SIS. Both matrices show good epithelialization and ingrowth of smooth muscle cells. Both biomatrices show considerable encrustation, which appears to disappear in time. The rabbit model is suitable for bladder tissue engineering studies as it is an easy model to use. In this model, besides tissue regeneration, also some of the clinical problems are seen such as encrustation of foreign body material in the bladder. These aspects are subject for further pre-clinical studies in this animal model.

Rabbit urethra replacement with a defined biomatrix or small intestinal submucosa

OBJECTIVE

The evaluation of collagen-based biomatrix (SIS COOK((R))) in comparison to a biochemically reconstructed biomatrix for replacement of the urethra in a rabbit model as a preclinical model.

MATERIAL AND METHODS

Rabbits underwent partial urethra replacement (resection of 0.5 to 1.0 cm segment of the urethra), which was replaced with 1 or 4 layers Small Intestinal Submucosa (SIS COOK) patch grafts or with a biochemically defined collagen biomatrix, partly sutured with unresolvable sutures for future reference. Six animals underwent a sham control operation. The grafts of regenerated urethras were harvested at 1, 3 and 9 months after implantation. Urethrography was performed pre-operatively and before sacrificing. The animals were evaluated macroscopically and by routine histology and immunohistochemistry.

RESULTS

At 1 month after implantation, the biomatrices (1 layer, 4 layers and our biochemically defined biomatrix) were well distinguishable from the normal surrounding tissues and showed blood vessels at the periphery. Macroscopically, the unresolvable reference sutures were easy to find at all time points. At 3 months the graft was still distinguishable in the 4 layers SIS group. In the 1 layer and the defined biomatrix group a good regeneration of the urethra within the graft was seen with some central fibrosis. Histological and immunohistochemical evaluation showed urothelium regeneration on the 1 layer and on biochemically defined biomatrix with decreasing number of inflammatory cells from 1 month on. In the group treated with 4 layers SIS the urothelium was completely regenerated at 3 months. Histologically, the regeneration of muscle cells in the three biomatrices was comparable. The smooth muscle cells regenerated very slowly as 1 month after implantation no muscle cells were detectable within the grafts. At 3 months a few muscle cells were present in the graft, but cell density did not increase in the following 6 months. Strictures were not observed on control urethrography pre-operatively in the animals. In one case slight narrowing of the urethra on urethrography was seen, but apparently without causing voiding problems. One rabbit developed a fistula near the operation site.

CONCLUSION

The biomatrices investigated are feasible scaffolds to repair urethral lesions. The results with our biochemically defined biomatrix are comparable to one layer Small Intestinal Submucosa. Almost no smooth muscle cells population was observed after nine months for the three biomatrices. We conclude that an improved molecularly defined biomatrix focussed on stimulation of smooth muscle cell growth may be necessary to obtain optimal cellular grafting results.

Metrical information load of lines and angles in line patterns

Acute angles and long lines are more complex than obtuse angles and short lines. This source of complexity is called metrical information, for which a measure was proposed by Leeuwenberg (1982). According to this measure, the metrical information of a static pattern is specified as the sum of the mechanical impulses necessary to move an object according to this pattern. The perceptual relevance of this metrical load was tested in an experiment in which judged complexities were gathered for a number of simple line patterns.