Cellular spartans at the pass: Emerging intricacies of cell competition in early and late tumorigenesis

Cell competition is a mechanism for cellular quality control based on cell-cell comparisons of fitness. Recent studies have unveiled a central and complex role for cell competition in cancer. Early tumors exploit cell competition to replace neighboring normal epithelial cells. Intestinal adenomas, for example, use cell competition to outcompete wild-type epithelial cells. However, oncogenic mutations do not always confer an advantage: wild-type cells can identify mutant cells and enforce their extrusion through cell competition, a process termed "epithelial defense against cancer". A particularly interesting situation emerges in metastasis: supercompetitive tumor cells encounter heterotypic partners and engage in reciprocal competition with diverging outcomes. This article sheds light on the emerging complexity of cell competition by highlighting recent studies that unveil its context dependency. Finally, we propose that tissue histomorphology implies a crucial role for cell competition at tumor invasion fronts particularly in metastases, warranting increased attention in future studies.

An idiosyncratic zonated stroma encapsulates desmoplastic liver metastases and originates from injured liver

A perimetastatic capsule is a strong positive prognostic factor in liver metastases, but its origin remains unclear. Here, we systematically quantify the capsule's extent and cellular composition in 263 patients with colorectal cancer liver metastases to investigate its clinical significance and origin. We show that survival improves proportionally with increasing encapsulation and decreasing tumor-hepatocyte contact. Immunostaining reveals the gradual zonation of the capsule, transitioning from benign-like NGFRhigh stroma at the liver edge to FAPhigh stroma towards the tumor. Encapsulation correlates with decreased tumor viability and preoperative chemotherapy. In mice, chemotherapy and tumor cell ablation induce capsule formation. Our results suggest that encapsulation develops where tumor invasion into the liver plates stalls, representing a reparative process rather than tumor-induced desmoplasia. We propose a model of metastases growth, where the efficient tumor colonization of the liver parenchyma and a reparative liver injury reaction are opposing determinants of metastasis aggressiveness.

Histopathological growth patterns of liver metastasis: updated consensus guidelines for pattern scoring, perspectives and recent mechanistic insights

The first consensus guidelines for scoring the histopathological growth patterns (HGPs) of liver metastases were established in 2017. Since then, numerous studies have applied these guidelines, have further substantiated the potential clinical value of the HGPs in patients with liver metastases from various tumour types and are starting to shed light on the biology of the distinct HGPs. In the present guidelines, we give an overview of these studies, discuss novel strategies for predicting the HGPs of liver metastases, such as deep-learning algorithms for whole-slide histopathology images and medical imaging, and highlight liver metastasis animal models that exhibit features of the different HGPs. Based on a pooled analysis of large cohorts of patients with liver-metastatic colorectal cancer, we propose a new cut-off to categorise patients according to the HGPs. An up-to-date standard method for HGP assessment within liver metastases is also presented with the aim of incorporating HGPs into the decision-making processes surrounding the treatment of patients with liver-metastatic cancer. Finally, we propose hypotheses on the cellular and molecular mechanisms that drive the biology of the different HGPs, opening some exciting preclinical and clinical research perspectives.

Stabilization of the classical phenotype upon integration of pancreatic cancer cells into the duodenal epithelium

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PDAC cells in the duodenal epithelium mimic intestinal cells and co-opt the basement membrane.

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Intramucosal PDAC location is strongly coupled to the classical phenotype and to intestinal traits.

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Intratumoral heterogeneity is linked to specific tissue compartments, which shape phenotype plasticity of PDAC cells.

Introduction

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive solid tumors. Based on transcriptomic classifiers, basal-like and classical PDAC subtypes have been defined that differ in prognosis. Cells of both subtypes can coexist in individual tumors; however, the contribution of either clonal heterogeneity or microenvironmental cues to subtype heterogeneity is unclear. Here, we report the spatial tumor phenotype dynamics in a cohort of patients in whom PDAC infiltrated the duodenal wall, and identify the duodenal epithelium as a distinct PDAC microniche.

Materials and methods

We used serial multiplex quantitative immunohistochemistry (smq-IHC) for 24 proteins to phenotypically chart PDAC tumor cells in patients whose tumors infiltrated the duodenal epithelium. Additionally, we used a genetically engineered mouse model to study the PDAC cell phenotype in the small intestinal epithelium in a controlled genetic background.

Result

We show that pancreatic cancer cells revert to non-destructive growth upon integration into the duodenal epithelium, where they adopt traits of intestinal cell differentiation, associated with phenotypical stabilization of the classical subtype. The integrated tumor cells replace epithelial cells in an adenoma-like manner, as opposed to invasive growth in the submucosa. Finally, we show that this phenomenon is shared between species, by confirming duodenal integration and phenotypic switching in a genetic PDAC mouse model.

Discussion

Our results identify the duodenal epithelium as a distinct PDAC microniche and tightly link microenvironmental cue to cancer transcriptional subtypes. The phenomenon of “intestinal mimicry” provides a unique opportunity for the systematic investigation of microenvironmental influences on pancreatic cancer plasticity.

Hedgehog Signaling in Colorectal Cancer: All in the Stroma?

Hedgehog (Hh) signaling regulates intestinal development and homeostasis. The role of Hh signaling in cancer has been studied for many years; however, its role in colorectal cancer (CRC) remains controversial. It has become increasingly clear that the “canonical” Hh pathway, in which ligand binding to the receptor PTCH1 initiates a signaling cascade that culminates in the activation of the GLI transcription factors, is mainly organized in a paracrine manner, both in the healthy colon and in CRC. Such canonical Hh signals largely act as tumor suppressors. In addition, stromal Hh signaling has complex immunomodulatory effects in the intestine with a potential impact on carcinogenesis. In contrast, non-canonical Hh activation may have tumor-promoting roles in a subset of CRC tumor cells. In this review, we attempt to summarize the current knowledge of the Hh pathway in CRC, with a focus on the tumor-suppressive role of canonical Hh signaling in the stroma. Despite discouraging results from clinical trials using Hh inhibitors in CRC and other solid cancers, we argue that a more granular understanding of Hh signaling might allow the exploitation of this key morphogenic pathway for cancer therapy in the future.

Different Response of Ptch Mutant and Ptch Wildtype Rhabdomyosarcoma Toward SMO and PI3K Inhibitors

Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma with poor prognosis. RMS frequently show Hedgehog (HH) pathway activity, which is predominantly seen in the embryonal subtype (ERMS). They also show activation of Phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) signaling. Here we compared the therapeutic effectiveness and the impact on HH target gene expression of Smoothened (SMO) antagonists with those of the PI3K inhibitor pictilisib in ERMS with and without mutations in the HH receptor Patched1 (PTCH). Our data demonstrate that growth of ERMS showing canonical Hh signaling activity due to Ptch germline mutations is efficiently reduced by SMO antagonists. This goes along with strong downregulation of the Hh target Gli1. Likewise Ptch mutant tumors are highly responsive toward the PI3K inhibitor pictilisib, which involves modulation of AKT and caspase activity. Pictilisib also modulates Hh target gene expression, which, however, is rather not correlated with its antitumoral effects. In contrast, sporadic ERMS, which usually express HH target genes without having PTCH mutation, apparently lack canonical HH signaling activity. Thus, stimulation by Sonic HE (SHH) or SAG (Smoothened agonist) or inhibition by SMO antagonists do not modulate HH target gene expression. In addition, SMO antagonists do not provoke efficient anticancer effects and rather exert off-target effects. In contrast, pictilisib and other PI3K/AKT/mTOR inhibitors potently inhibit cellular growth. They also efficiently inhibit HH target gene expression. However, of whether this is correlated with their antitumoral effects it is not clear. Together, these data suggest that PI3K inhibitors are a good and reliable therapeutic option for all ERMS, whereas SMO inhibitors might only be beneficial for ERMS driven by PTCH mutations.

Canonical WNT/β-Catenin Signaling Plays a Subordinate Role in Rhabdomyosarcomas

The development of skeletal muscle from immature precursors is partially driven by canonical WNT/β-catenin signaling. Rhabdomyosarcomas (RMS) are immature skeletal muscle-like, highly lethal cancers with a variably pronounced blockade of muscle differentiation. To investigate whether canonical β-catenin signaling in RMS is involved in differentiation and aggressiveness of RMS, we analyzed the effects of WNT3A and of a siRNA-mediated or pharmacologically induced β-catenin knock-down on proliferation, apoptosis and differentiation of embryonal and alveolar RMS cell lines. While the canonical WNT pathway was maintained in all cell lines as shown by WNT3A induced AXIN expression, more distal steps including transcriptional activation of its key target genes were consistently impaired. In addition, activation or inhibition of canonical WNT/β-catenin only moderately affected proliferation, apoptosis or myodifferentiation of the RMS tumor cells and a conditional knockout of β-catenin in RMS of Ptch ^del/+ mice did not alter RMS incidence or multiplicity. Together our data indicates a subordinary role of the canonical WNT/β-catenin signaling for RMS proliferation, apoptosis or differentiation and thus aggressiveness of this malignant childhood tumor.

Metal-assisted electrochemical etching of silicon

In this paper the metal-assisted electrochemical etching of silicon is introduced. By electrochemical measurement and sequent simulation, it is revealed that the potential of the valence band maximum at the silicon/metal interface is more negative than that of the silicon/electrolyte interface. Accordingly, holes injected from the back contact are driven preferentially to the silicon/metal interface. Consequently, silicon below metal is electrochemically etched much faster than a naked silicon surface without metal coverage. Metals such as Ag and Cu have been utilized to catalyze the electrochemical etching. Feature sizes as small as 30 nm can be achieved by metal-assisted electrochemical etching. Meanwhile, the metal-assisted electrochemical etching method enables convenient control over the etching direction of non-(100) substrates, and facilitates the fabrication of orientation-modulated silicon nanostructures.

Contributing to the ICNPR: validating the term 'informal settlement'

AIM

The specific aims of this study were to propose a definition of the term informal settlement, validate the term informal settlement, and submit a term and definition for international utilization to the International Council of Nurses (ICN) for consideration for inclusion in the International Classification of Nursing Practice (ICNP).

BACKGROUND

South Africa was one of four African countries (Botswana, South Africa, Swaziland and Zimbabwe) funded by the WK Kellogg Foundation to participate in the ICNP project. South Africa had two research groups. One of the research groups identified the term informal settlement to define.

METHODS

This was a qualitative study where a philosophical perspective was used to explore, explain and describe nursing practice. The combined method proposed by the ICN was utilized to define and validate the term informal settlement.

FINDINGS

Validation and literature review provided sufficient support for the defined characteristics and the term was finally defined and submitted to ICN on 12 April 2001 as informal settlement is a type of residential development with the specific characteristics--temporary residential structures, erected with limited or no formal infrastructure, densely populated, no secure tenure for occupants, no property demarcations, often associated with overcrowding/limited or no privacy, and low standard of living, being situated in high risk areas with an increased risk for disease and disasters.

CONCLUSION

The ICNP Evaluation Committee recommended inclusion in the ICNP with minor changes in February 2003.

Contributing to the ICNP: validating the term cultural diversity

AIM

The specific aims of this study were to: Propose a definition of the term cultural diversity; Validate the term cultural diversity; and Submit a term and definition for international utilisation to the International Council of Nurses (ICN) for consideration for inclusion in the ICNP.

BACKGROUND

South Africa was one of four African countries (Botswana, South Africa, Swaziland, and Zimbabwe) funded by the WK Kellogg Foundation to participate in the ICNP project. South Africa had 2 research groups. One of the research groups identified the term cultural diversity to define.

METHOD

This was a qualitative study where a philosophical perspective was used to explore, explain and describe nursing practice. The combined method proposed by the International Council of Nurses (ICN) was utilised to define and validate the term cultural diversity.

FINDINGS

Validation and literature review provided sufficient support for the defined characteristics and the term was finally defined and submitted to ICN in November 2002 as: CULTURAL DIVERSITY is a type of CULTURE with the specific characteristics: co-existence of different groups, e.g. ethnic, religious, linguistic and other groups each with their own values and belief systems, traditions and different lifestyles.

CONCLUSION

The research group was informed in December 2003 of the ICNP Evaluation Committee recommendation that the term cultural diversity will be included in the ICNP.

Enabling legislation in diagnosis and prescribing of medicine by nurses/health practitioners

The South African health system has undergone major changes over the last 5-10 years. These rapid changes have not only significantly increased the visibility of the nurse practitioner in South Africa, but are also posing challenges to the profession and health care services that need to be addressed. In its Health Policies the Government has indicated that the nursing/midwifery profession, as the biggest group of health care professionals, should be the practitioners to provide primary health care services to the communities. But to do this, they require enabling legislation. The "permit system" has been in place for non-pharmacists and institutions other than hospitals and pharmacies to acquire, possess, use and supply medication for a number of years. This system has been fraught with problems mainly due to a lack of clarity on exactly how the system works and the system had been abused. The purpose of this article is to explore the current situation with the aim to analyze the legal framework that exists within which the primary health care services, and specifically the diagnosing and prescribing of medication, could be performed. The conclusion is made that health legislation has not kept up with the rapid changes in service delivery and are not adequate to empower the nurse to deliver health services. Some recommendations are made for the way forward.

[X-rays taken by nurses]

Medical technology makes use of ionising radiation in many ways to diagnose and treat disease. One of these is X-rays. In rural areas there are hospitals where the services of a radiographer are not available and nurses take over this task. No formal training is available for these nurses in order to equip them with the necessary knowledge and skills to take X-rays. This article looks into the nature of this phenomenon.

Rolipram in major depressive disorder: results of a double-blind comparative study with imipramine

Rolipram improves signal transmission in central noradrenergic neurones at a pre- and postsynaptic level, and is thus a novel approach in antidepressant therapy. In order to prove efficacy, tolerance, and safety, several controlled studies are underway. Results of a randomized double-blind comparative trial versus imipramine involving 64 in-patients with Major Depressive Disorder (DSM III) in six independent centers will be presented and discussed. The chosen biometric model provided evidence that towards the end of the study imipramine was superior to Rolipram. The particular clinical relevance of this difference is discussed. As regards tolerance, nausea emerged as the typical side-effect of Rolipram, whereas imipramine precipitated mainly anticholinergic side-effects.

[Preliminary physiological and psychological results under various electroclimatic conditions (author's transl)]

Before the start of a research project which was to stretch over a period of several years, characteristics of the control space were to be defined. Therefore the influence of spherics and 50 Hz-alternating fields in the unscreened control space were studied.--Pupils (Foster children) were the test subjects. Each test subject was subjected to the conditions of the control space as well as the testing space.--Two classes of parameters were studied. Blood sugar, blood pressure and pulse rate were recorded as physiological dimensions. Short-term memory, powers of concentration as well as the subjective well-being were the psychological parameters.--As to the parameters examined, no significant difference between testing and control space conditions was recorded. In order to examine whether the climatic factors of the control space have an antagonistic effect on the variables in question, their influence was studied separately in two further investigations. In order to clarify this problem, spherics-impulses in the 10 Khz range were given in screened space ("Vorversuch 2"/preliminary experiment 2), then--in, "Vorversuch 3"/preliminary experiment 3 - a 50 Hz-alternating field was applied. For each of the climatic factors under examination the influence on each single parameter was negative. The assumption of an antagonistic effect which would hinder the definition of standard spatial conditions was thereby shown to be incorrect.