Signaling via beta1 integrins and mitogen-activated protein kinase determines human epidermal stem cell fate in vitro

Human epidermal stem cells express higher levels of beta1 integrins and are more adhesive than keratinocytes that are destined to differentiate. To investigate whether high beta1 integrin expression and adhesiveness are essential for maintaining keratinocytes in the stem cell compartment, we introduced a dominant-negative beta1 integrin mutant, CD8beta1, into cultured human keratinocytes, thereby interfering with beta1 integrin function. Surface beta1 integrin levels, adhesiveness, and mitogen-activated protein (MAP) kinase activation on fibronectin were reduced, and exit from the stem cell compartment was stimulated. Adhesiveness and proliferative potential were restored by overexpressing wild-type beta1 integrin or by constitutive MAP kinase activation. Conversely, a dominant-negative MAP kinase kinase 1 mutant decreased adhesiveness and stem cell number in the absence of CD8beta1. MAP kinase activation by alpha6beta4-mediated adhesion and mitogens was normal in CD8beta1 cells, and constitutive MAP kinase activation did not affect adhesion and proliferation of control keratinocytes. We conclude that beta1 integrins and MAP kinase cooperate to maintain the epidermal stem cell compartment in vitro.

beta-catenin signalling modulates proliferative potential of human epidermal keratinocytes independently of intercellular adhesion

We found that cultured human keratinocytes with high proliferative potential, the putative epidermal stem cells, expressed a higher level of noncadherin-associated beta-catenin than populations enriched for keratinocytes of lower proliferative potential. To investigate the physiological significance of this, a series of beta-catenin constructs was introduced into keratinocytes via retroviral infection. Full-length beta-catenin and a mutant containing only nine armadillo repeats had little effect on proliferative potential in culture, the full-length protein being rapidly degraded. However, expression of stabilised, N-terminally truncated beta-catenin increased the proportion of putative stem cells to almost 90% of the proliferative population in vitro without inducing malignant transformation, and relieved the differentiation stimulatory effect of overexpressing the E-cadherin cytoplasmic domain. Conversely, beta-catenin lacking armadillo repeats acted as a dominant negative mutant and stimulated exit from the stem cell compartment in culture. The positive and negative effects of the beta-catenin mutants on proliferative potential were independent of effects on cell-cycle kinetics, overt terminal differentiation or intercellular adhesion, and correlated with stimulation or inhibition of transactivation of a TCF/LEF reporter in basal keratinocytes. We conclude that the elevated level of cytoplasmic beta-catenin in those keratinocytes with characteristics of epidermal stem cells contributes to their high proliferative potential.

Expression of a dominant negative cadherin mutant inhibits proliferation and stimulates terminal differentiation of human epidermal keratinocytes

Cell adhesion molecules are not only required for maintenance of tissue integrity, but also regulate many aspects of cell behaviour, including growth and differentiation. While the regulatory functions of integrin extracellular matrix receptors in keratinocytes are well established, such functions have not been investigated for the primary receptors that mediate keratinocyte intercellular adhesion, the cadherins. To examine cadherin function in normal human epidermal keratinocytes we used a retroviral vector to introduce a dominant negative E-cadherin mutant, consisting of the extracellular domain of H-2Kd and the transmembrane and cytoplasmic domains of E-cadherin. As a control a vector containing the same construct, but with the catenin binding site destroyed, was prepared. High levels of expression of the constructs were achieved; the dominant negative mutant, but not the control, formed complexes with alpha-, beta- and gamma-catenin. In cells expressing the dominant negative mutant there was a 5-fold decrease in the level of endogenous cadherins and a 3-fold increase in the level of beta-catenin. Cell-cell adhesion and stratification were inhibited by the dominant negative mutant and desmosome formation was reduced. Expression of the mutant resulted in reduced levels of the alpha 2 beta 1 and alpha 3 beta 1 integrins and increased cell motility, providing further evidence for cross-talk between cadherins and the beta 1 integrins. In view of the widely documented loss of E-cadherin in keratinocyte tumours it was surprising that the dominant negative mutant had an inhibitory effect on keratinocyte proliferation and stimulated terminal differentiation even under conditions in which intercellular adhesion was prevented. These results establish a role for cadherins in regulating keratinocyte growth and differentiation and raise interesting questions as to the relative importance of cell adhesion-dependent and -independent mechanisms.

Optimised retroviral infection of human epidermal keratinocytes: long-term expression of transduced integrin gene following grafting on to SCID mice

Previous attempts to achieve long-term gene expression in retrovirally transduced human epidermal keratinocytes in vivo have been largely unsuccessful. This has been variously attributed to a failure to target epidermal stem cells, suboptimal grafting conditions or inactivation of the retroviral vector. In an attempt to overcome these problems we expressed the chick beta 1 integrin subunit in primary human epidermal keratinocytes, which allowed us to monitor retroviral gene expression on a cell-by-cell basis. We describe optimised methods for selecting high-titre amphotropic packaging cells and for infecting keratinocytes in culture. When transduced cells were grafted into mice, graft survival was comparable in nude and SCID mice, but it was essential to combine the keratinocytes with a dermal substrate. Using these methods the majority of keratinocytes expressed the chick beta 1 integrin subunit for at least 16 weeks after grafting. We conclude that epidermal keratinocytes are attractive recipient cells for gene therapy.

Functional interaction between E-cadherin and alphav-containing integrins in carcinoma cells

We have demonstrated the possibility of cross-talk between E-cadherin and alphav integrins in breast carcinoma cells. Using the function-blocking anti-alphav monoclonal antibody 17E6, applied to monolayer cultures of breast cancer lines, it was found that treatment of cells possessing detergent-insoluble (implying attachment to the actin cytoskeleton) E-cadherin resulted in the adoption of a spheroid configuration of cell growth. This effect was dependent upon not just alphav occupancy but also receptor aggregation. Thus in vitro alphav-dependent adhesion suppresses E-cadherin-mediated morphological changes. To investigate whether manipulation of E-cadherin would, conversely, modulate integrin activity we introduced a dominant-negative E-cadherin construct into one of the lines, ZR75-1, giving rise to the cell line ZR-E2R1. Surface expression of endogenous E-cadherin was downregulated (by around 25%), whereas beta-catenin levels were increased two- to threefold in ZR-E2R1 cells. There was also a highly significant increase in migration of ZR-E2R1 cells (relative to control cells) toward vitronectin (P<0.001), but not toward collagen type I, fibronectin or laminin. Such increased migration could be abrogated totally by antibody blockade of alphavbeta5 and alphavbeta1 integrins. There was no detectable change in alphav integrin levels. These data suggest that the introduction of a dominant-negative E-cadherin mutant into ZR75-1, in addition to a loss of cohesion, generates a signal (or signals) which increases migration towards vitronectin through increased activity of alphav integrins.

Predicting Therapeutic Antibody Delivery into Human Head and Neck Cancers

PURPOSE

The efficacy of antibody-based therapeutics depends on successful drug delivery into solid tumors; therefore, there is a clinical need to measure intratumoral antibody distribution. This study aims to develop and validate an imaging and computation platform to directly quantify and predict antibody delivery into human head and neck cancers in a clinical study.

EXPERIMENTAL DESIGN

Twenty-four patients received systemic infusion of a near-infrared fluorescence-labeled therapeutic antibody followed by surgical tumor resection. A computational platform was developed to quantify the extent of heterogeneity of intratumoral antibody distribution. Both univariate and multivariate regression analyses were used to select the most predictive tumor biological factors for antibody delivery. Quantitative image features from the pretreatment MRI were extracted and correlated with fluorescence imaging of antibody delivery.

RESULTS

This study not only confirmed heterogeneous intratumoral antibody distribution in-line with many preclinical reports, but also quantified the extent of interpatient, intertumor, and intratumor heterogeneity of antibody delivery. This study demonstrated the strong predictive value of tumor size for intratumoral antibody accumulation and its significant impact on antibody distribution in both primary tumor and lymph node metastasis. Furthermore, this study established the feasibility of using contrast-enhanced MRI to predict antibody delivery.

CONCLUSIONS

This study provides a clinically translatable platform to measure antibody delivery into solid tumors and yields valuable insight into clinically relevant antibody tumor penetration, with implications in the selection of patients amenable to antibody therapy and the design of more effective dosing strategies.

Lack of intrinsic polarity in the ligand-binding ability of keratinocyte beta1 integrins

Within the basal layer of the epidermis the beta1 integrins have a pericellular distribution. Two monoclonal antibodies, 15/7 and 12G10, that detect a conformation of the beta1 integrin subunit that is induced following cation or ligand occupancy selectively recognized beta1 integrins at the basement membrane zone in vivo and in focal adhesions of cultured keratinocytes; they did not recognize integrins on the apical and upper lateral membranes of basal keratinocytes nor integrins on the suprabasal keratinocytes of hyperproliferative epidermis. Inhibition of intercellular adhesion did not induce the 15/7 epitope on the lateral and apical membrane domains. The surface distribution of the epitopes was consistent with the antibodies acting as reporters of ligand-binding; in addition, the 15/7 epitope was exposed on unglycosylated, immature beta1 integrins. Although the apical membrane of basal keratinocytes is not normally in contact with extracellular matrix proteins, we found that it was capable of binding fibronectin-coated beads and that the 15/7 epitope was exposed on plasma membrane in contact with the beads. When a chimeric molecule consisting of the extracellular domain of CD8 and the cytoplasmic domain of the beta1 integrin subunit, used to mimic a constitutively active beta1 heterodimer, was introduced into keratinocytes it localized to the basal, lateral and apical membrane domains. We conclude that although the conformation of the keratinocyte beta1 integrins differs between the basal and the lateral/apical membrane domains there is no intrinsic polarity in the ligand binding potential of the receptors.

[An investigation of the fertility needs of young patients with breast cancer]

Objective: To investigate the fertility needs and outcome of pregnancy in patients with young breast cancer in China. Methods: A retrospective cross-sectional investigation was conducted on 374 young breast cancer women from Cancer Hospital, Chinese Academy of Medical Sciences. Young patients with breast cancer were defined as patients who got initial diagnosis of breast cancer at age no more than 40 years old. We conducted a questionnaire survey and collected clinical data from medical chart. Logistic regression model was used to analyze the possible factors influencing patients' fertility intention. Results: 308 young women with breast cancer completed questionnaires, and the response rate was 82.4%. 81 patients (26.3%) had fertility needs after diagnosis. Of them, 6 cases took active measures to preserve fertility. 72 patients (23.4%) received fertility counseling during treatment. 7 patients were successfully pregnant, including four cases who delivered normally. Multivariate logistic regression analysis showed that patients under 35 years old (OR=4.81), bachelor degree or above (OR=3.26), receiving breast-conserving surgery (OR=2.15) and childless patients (OR=3.03) were more likely to have fertility needs after diagnosis of breast cancer (all P<0.05). Conclusions: The fertility needs of young breast cancer women in China are gradually increasing. Healthcare providers associated with tumor patients should actively offer corresponding fertility consultation and individualized diagnosis and therapy plans for patients with fertility needs.

High-Resolution Profiling of Human Vocal Fold Cellular Landscapes With Single-Nuclei RNA Sequencing

INTRODUCTION

The function of the vocal folds (VFs) is determined by the phenotype, abundance, and distribution of differentiated cells within specific microenvironments. Identifying this histologic framework is crucial in understanding laryngeal disease. A paucity of studies investigating VF cellular heterogeneity has been undertaken. Here, we examined the cellular landscape of human VFs by utilizing single-nuclei RNA-sequencing.

METHODS

Normal true VF tissue was excised from five patients undergoing pitch elevation surgery. Tissue was snap frozen in liquid nitrogen and subjected to cellular digestion and nuclear extraction. Nuclei were processed for single-nucleus sequencing using the 10X Genomics Chromium platform. Sequencing reads were assembled using cellranger and analyzed with the scanpy package in python.

RESULTS

RNA sequencing revealed 18 global cell clusters. While many were of epithelial origin, expected cell types, such as fibroblasts, immune cells, muscle cells, and endothelial cells were present. Subcluster analysis defined unique epithelial, immune, and fibroblast subpopulations.

CONCLUSION

This study evaluated the cellular heterogeneity of normal human VFs by utilizing single-nuclei RNA-sequencing. With further confirmation through additional spatial sequencing and microscopic imaging, a novel cellular map of the VFs may provide insight into new cellular targets for VF disease.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:3193-3200, 2024.

genomeSidekick: A user-friendly epigenomics data analysis tool

Recent advances in epigenomics measurements have resulted in a preponderance of genomic sequencing datasets that require focused analyses to discover mechanisms governing biological processes. In addition, multiple epigenomics experiments are typically performed within the same study, thereby increasing the complexity and difficulty of making meaningful inferences from large datasets. One gap in the sequencing data analysis pipeline is the availability of tools to efficiently browse genomic data for scientists that do not have bioinformatics training. To bridge this gap, we developed genomeSidekick, a graphical user interface written in R that allows researchers to perform bespoke analyses on their transcriptomic and chromatin accessibility or chromatin immunoprecipitation data without the need for command line tools. Importantly, genomeSidekick outputs lists of up- and downregulated genes or chromatin features with differential accessibility or occupancy; visualizes omics data using interactive volcano plots; performs Gene Ontology analyses locally; and queries PubMed for selected gene candidates for further evaluation. Outputs can be saved using the user interface and the code underlying genomeSidekick can be edited for custom analyses. In summary, genomeSidekick brings wet lab scientists and bioinformaticians into a shared fluency with the end goal of driving mechanistic discovery.

[Evaluation of the predictive effect of PD-L1 expression on survival in early triple-negative breast cancer]

Objectives: To find the prognostic factors related to early triple-negative breast cancer to optimize the therapeutic strategies, and explore the influence of programmed cell death ligand-1(PD-L1)expression in early triple-negative breast cancer on its prognosis, so as to provide support for clinical treatment decisions. Methods: Early triple-negative breast cancer patients treated at the National Cancer Center, National Clinical Research Center for Cancer, Cancer Hospital, Chinese Academy of Medical Sciences during 1st June, 2009 and 31st Oct, 2015 were enrolled in this study. All the clinicopathological data of patients were collected, and the paraffin sections of the surgical specimens were stained with estrogen receptor, progesterone receptor, human epidermal growth factor receptor-2, secreted protein acidic and rich in cysteine (SPARC), androgen receptor, PD-L1 and other antibodies by the immunohistochemical method. Kaplan-Meier survival and Cox regression curves were used for survival analysis of relevant clinical and pathological results and nomogram survival prediction models were established to explore the influence of relevant factors on the prognosis. Results: A total of 205 patients with triple-negative breast cancer were enrolled. Ninety patients (43.9%) were PD-L1 positive. The median follow-up time was 63 months. Thirty-seven patients were relapsed or recurrent and 16 patients were dead. The 5-year disease-free survival (DFS) rate and overall survival (OS) rate were 86.1% (95% CI: 81.4%-90.8%) and 93.6% (95% CI: 91.0%-97.6%), respectively, in the general population. Univariate Cox regression analysis showed that PD-L1 expression and lymph node metastasis were correlated with DFS and OS (P<0.05). In multivariate analysis, PD-L1 expression was an independent influencing factor of DFS, with PD-L1 positive patients possessing a significant survival benefit in DFS (HR=0.31, 95% CI: 0.13-0.73). Lymph node metastasis was an independent influencing factor of OS, and OS was significantly shortened in patients with positive lymph node metastasis (HR=3.24, 95% CI: 1.15-9.17). PD-L1, lymph node metastasis, menopausal status, Ki-67 index and adjuvant chemotherapy regimen were included to establish the 1- and 3-year DFS and OS nomogram prediction models, resulting in C indices of 0.698 and 0.748, respectively. Conclusions: PD-L1 expression is a predictive biomarker of good prognostic factor in triple-negative breast cancer patients. DFS is significantly prolonged in PD-L1 positive patients and OS also shows a prolongation trend. The nomogram prognosis prediction models have reference values for adjuvant chemotherapy in this patient group.