Heparin-binding EGF-like growth factor shows transient left–right asymmetrical expression in mouse myotome pairs

Evaluating the Effects of Cryopreservation on the Viability and Gene Expression of Porcine-Ear-Skin Fibroblasts

Owing to the inherent heterogeneity and plasticity of fibroblasts, they are considered as the conventional biological resources for basic and clinical medical research. Thus, it is essential to generate knowledge about the establishment of fibroblast cultures and the effects of cryopreservation processes on their biological characteristics. Since the pig (Sus scrofa) possesses numerous genetic, physiological, and anatomical similarities with humans, porcine fibroblasts are naturally regarded as useful analogues of human fibroblasts. Nonetheless, less attention has been given to the alterations in viability and gene expression of cryopreserved porcine fibroblasts. In this study, we aimed to obtain fibroblasts from porcine ear skin and evaluate the effects of cryopreservation on the cell survival, proliferation, and gene expression profiles of the fibroblasts by trypan-blue-staining assay, Cell Counting kit-8 (CCK-8) assay, and RNA-sequencing analysis, respectively. Our results suggested that morphologically stable fibroblast cultures can be constructed from pig-ear skin. The post-thaw survival rate of the cryopreserved fibroblasts at 0 h and 24 h was over 90%. The proliferative activity of the cryopreserved fibroblasts was similar to that of the non-cryopreserved fibroblasts after 7 days of in vitro culture, which suggested that cryopreservation did not influence the viability. The RNA-sequencing analysis indicated that this should be attributed to the 867 differentially expressed genes (DGEs) identified, which are involved in molecular process related to cell recovery and survival after cryo-stimulation. In addition, eight important DEGs BMP2, GDF15, EREG, AREG, HBEGF, LIF, IL-6, and HOX-7 could potentially be applied to improve the efficiency of fibroblast cryopreservation, but comprehensive and systematic studies on understanding the underlying mechanisms responsible for their modulatory roles are urgently needed.

Clinicopathological features and prognosis associated with breast cancer laterality: a nationwide study from the Korean Breast Cancer Society

Purpose

Although breast cancer is known to show a left predominance, the clinical characteristics and causes underlying this finding remain unclear. In addition, no related studies on breast cancer laterality have been conducted in patients with breast cancer in Korea. Therefore, we aimed to analyze differences in breast cancer laterality and the associated clinicopathological characteristics and prognosis among Korean patients with breast cancer.

Methods

We conducted a retrospective analysis using large-scale data on clinicopathological factors and prognosis differences related to breast cancer laterality from the Korean Breast Cancer Society Registration system. The left-to-right ratio (LRR) of breast cancer was calculated through binomial distribution, and factors related to breast cancer laterality were identified through logistic regression analysis. In addition, the differences in the survival rates for left and right breast cancers were analyzed using the Kaplan-Meier method and Cox proportional hazards model.

Results

In 171,500 patients, the LRR was 1.031 (95% confidence interval, 1.022-1.041; P < 0.001). Multivariate analysis showed that the ratio of left breast cancer was related to age, body mass index (BMI), location, and human epidermal growth factor receptor 2 (HER2) status. The survival rate of patients with left and right breast cancers showed no significant difference.

Conclusion

A large-scale analysis revealed a left predominance in breast cancer laterality in Korean patients. Over time, this predominance gradually decreased. Age, BMI, location, and HER2 status affected breast cancer laterality. However, while left breast cancer showed relatively aggressive characteristics, it was not associated with a difference in the survival rate.

Divergent Impact of Breast Cancer Laterality on Clinicopathological, Angiogenic, and Hemostatic Profiles: A Potential Role of Tumor Localization in Future Outcomes

To date, lateral differences of invasive breast cancer (IBrC) with respect to the angiogenic and hemostatic profiles were never studied. Here, we aimed to determine the relationship of tumor laterality with various clinical and pathological parameters including angiogenic and hemostatic profiles. A total of 92 women that were initially non-metastatic and treated by surgery were included in this single-center prospective study. Patients were grouped according to tumor localization. A four-year follow-up was accomplished in all patients with a 15.22% recurrence rate. An immunoassay of selected angiogenic and hemostatic parameters, as well as immunohistochemistry of estrogen and progesterone receptors, human epidermal growth factor receptor 2 (HER2), and Ki67, was comparatively performed in groups with right- and left-sided IBrC. The same analysis was carried out in a subgroup of patients with luminal A molecular subtype of cancer. Patients with right-sided tumors free of nodal involvement had a significantly longer overall survival compared to their left-sided counterparts (p = 0.0491). Additionally, right-sided tumors had a higher predisposition to be a luminal-A subtype of IBrC (p = 0.0016). Furthermore, 10% of left-sided tumors exhibited an overexpression of HER2, while only 2% patients suffering right-sided tumors displayed a positive score (p = 0.0357). Our findings revealed a significantly higher concentration of vascular endothelial growth factor (VEGF)-A (p = 0.0136), lower anti-angiogenic ratios (sVEGFR1/VEGF-A (p = 0.0208) and sVEGFR2/VEGF-A (p = 0.0068)), and elevated plasminogen activator inhibitor type 1 (PAI-1) (p = 0.0229) in patients with breast cancer localized in the left breast, regardless of the molecular subtype of IBrC. Our study showed that left-sided breast tumors without lymph node metastases demonstrate worse overall survival. Laterality of IBrC is associated with pro-angiogenic and pro-thrombotic conditions. We propose to consider laterality as a prognostic factor of IBrC.

Left-right analysis of mammary gland development in retinoid X receptor-α+/- mice

Left-right (L-R) differences in mammographic parenchymal patterns are an early predictor of breast cancer risk; however, the basis for this asymmetry is unknown. Here, we use retinoid X receptor alpha heterozygous null (RXRα^+/-) mice to propose a developmental origin: perturbation of coordinated anterior-posterior (A-P) and L-R axial body patterning. We hypothesized that by analogy to somitogenesis-in which retinoic acid (RA) attenuation causes anterior somite pairs to develop L-R asynchronously-that RA pathway perturbation would likewise result in asymmetric mammary development. To test this, mammary glands of RXRα^+/- mice were quantitatively assessed to compare left- versus right-side ductal epithelial networks. Unlike wild-type controls, half of the RXRα^+/- thoracic mammary gland (TMG) pairs exhibited significant L-R asymmetry, with left-side reduction in network size. In RXRα^+/- TMGs in which symmetry was maintained, networks had bilaterally increased size, with left networks showing greater variability in area and pattern. Reminiscent of posterior somites, whose bilateral symmetry is refractory to RA attenuation, inguinal mammary glands (IMGs) also had bilaterally increased network size, but no loss of symmetry. Together, these results demonstrate that mammary glands exhibit differential A-P sensitivity to RXRα heterozygosity, with ductal network symmetry markedly compromised in anterior but not posterior glands. As TMGs more closely model human breast development than IMGs, these findings raise the possibility that for some women, breast cancer risk may initiate with subtle axial patterning defects that result in L-R asymmetric growth and pattern of the mammary ductal epithelium.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.

Mammary glands exhibit molecular laterality and undergo left-right asymmetric ductal epithelial growth in MMTV-cNeu mice

Significant left-right (L-R) differences in tumor incidence and disease outcome occur for cancers of paired organs, including the breasts; however, the basis for this laterality is unknown. Here, we show that despite their morphologic symmetry, left versus right mammary glands in wild-type mice have baseline differences in gene expression that are L-R independently regulated during pubertal development, including genes that regulate luminal progenitor cell renewal, luminal cell differentiation, mammary tumorigenesis, tamoxifen sensitivity and chemotherapeutic resistance. In MMTV-cNeu(Tg/Tg) mice, which model HER2/Neu-amplified breast cancer, baseline L-R differences in mammary gene expression are amplified, sustained or inverted in a gene-specific manner and the mammary ductal epithelium undergoes L-R asymmetric growth and patterning. Comparative genomic analysis of mouse L-R mammary gene expression profiles with gene expression profiles of human breast tumors revealed significant linkage between right-sided gene expression and decreased breast cancer patient survival. Collectively, these findings are the first to demonstrate that mammary glands are lateralized organs, and, moreover, that mammary glands have L-R differential susceptibility to HER2/Neu oncogene-mediated effects on ductal epithelial growth and differentiation. We propose that intrinsic molecular laterality may have a role in L-R asymmetric breast tumor incidence and, furthermore, that interplay between the L-R molecular landscape and oncogene activity may contribute to the differential disease progression and patient outcome that are associated with tumor situs.

Positional variations in mammary gland development and cancer

Most mammals develop their mammary glands in pairs of which the two counterparts are symmetrically displaced away from the ventral midline. Based on this symmetry and the same functional outcome as a milk-producing organ, the mammary glands are easily presumed to be mere copies of one another. Based on our analysis of published data with inclusion of new results related to mammary development and pathology in mice, we argue that this presumption is incorrect: Between and within pairs, mammary glands differ from one another, and tumor incidence and biology depend on the position along the anterior-posterior and the left-right axis as well. This insight has implications for experimental designs with mouse models and for data extrapolation between mammary glands within and between species. We suggest that improved documentation of location-specific mammary gland features will lead to more insights into the molecular mechanisms of mammary gland development and cancer biology in both mice and humans.

Neurally Derived Tissues in Xenopus laevis Embryos Exhibit a Consistent Bioelectrical Left-Right Asymmetry

Consistent left-right asymmetry in organ morphogenesis is a fascinating aspect of bilaterian development. Although embryonic patterning of asymmetric viscera, heart, and brain is beginning to be understood, less is known about possible subtle asymmetries present in anatomically identical paired structures. We investigated two important developmental events: physiological controls of eye development and specification of neural crest derivatives, in Xenopus laevis embryos. We found that the striking hyperpolarization of transmembrane potential (V_mem) demarcating eye induction usually occurs in the right eye field first. This asymmetry is randomized by perturbing visceral left-right patterning, suggesting that eye asymmetry is linked to mechanisms establishing primary laterality. Bilateral misexpression of a depolarizing channel mRNA affects primarily the right eye, revealing an additional functional asymmetry in the control of eye patterning by V_mem. The ATP-sensitive K⁺ channel subunit transcript, SUR1, is asymmetrically expressed in the eye primordia, thus being a good candidate for the observed physiological asymmetries. Such subtle asymmetries are not only seen in the eye: consistent asymmetry was also observed in the migration of differentiated melanocytes on the left and right sides. These data suggest that even anatomically symmetrical structures may possess subtle but consistent laterality and interact with other developmental left-right patterning pathways.

Acute vascular endothelial growth factor expression during hypertrophy is muscle phenotype specific and localizes as a striated pattern within fibres

Skeletal muscle hypertrophy requires the co-ordinated expression of locally acting growth factors that promote myofibre growth and concurrent adaptive changes in the microvasculature. These studies tested the hypothesis that vascular endothelial growth factor (VEGF) and heparin-binding epidermal growth factor (HB-EGF) expression are upregulated during the early stages of compensatory muscle growth induced by chronic functional overload (FO). Bilateral FO of the plantaris and soleus muscles was induced for 3 or 7 days in the hindlimbs of adult female Sprague-Dawley rats (n = 5 per group) and compared with control (non-FO) rats. Relative muscle mass (in mg (kg body weight)(-1)) increased by 18 and 24% after 3 days and by 20 and 33% after 7 days in the plantaris and soleus muscles, respectively. No differences in HB-EGF mRNA or protein were observed in either muscle of FO rats relative to control muscles. The VEGF mRNA was similar in the soleus muscles of FO and control rats, whereas a significant elevation occurred at 3 and 7 days of FO in the plantaris muscle. However, VEGF protein expression after 3 days of FO exhibited a differential response; expression in the soleus muscle decreased 1.6-fold, whereas that in the plantaris muscle increased 1.8-fold compared with the control muscle. After 7 days of FO, VEGF protein remained elevated within the plantaris muscle, but returned to basal levels in the soleus. Robust basal HB-EGF and VEGF protein expression was consistently seen in control muscles. In all groups, immunohistochemistry for VEGF protein displayed a distinct striated expression pattern within myofibres, with considerably less labelling in extracellular spaces. Constitutive expression of HB-EGF and VEGF in control myofibres is consistent with housekeeping roles for these growth factors in skeletal muscle tissue. However, the specific patterns of VEGF expression in these muscles during FO may reflect the chronic changes in neural recruitment between muscles and the co-ordination of angiogenic and/or other hypertrophic responses.

Muscle stem cells

Despite being mainly composed of highly differentiated contractile fibers, the adult skeletal muscle possesses the remarkable ability to regenerate, following injury. The cells that are responsible for this capacity are the satellite cells, a small population of adult stem cells positioned under the basal lamina of muscle fibers and that can give rise to both differentiated myogenic cells while maintaining a stem cell pool by a self-renewal mechanism. We will discuss here recent publications on the developmental origin of muscle stem cells, on the signaling pathways that affect their proliferation and differentiation, with reference to works on skeletal muscle formation in the embryo as well as the adult, using the mouse and chick as reference models.

What's left in asymmetry?

Left-right patterning is a fascinating problem of morphogenesis, linking evolutionary and cellular signaling mechanisms across many levels of organization. In the past 15 years, enormous progress has been made in elucidating the molecular details of this process in embryos of several model species. While many outside the field seem to believe that the fundamental aspects of this pathway are now solved, workers on asymmetry are faced with considerable uncertainties over the details of specific mechanisms, a lack of conceptual unity of mechanisms across phyla, and important questions that are not being pursued in any of the popular model systems. Here, we suggest that data from clinical syndromes, cryptic asymmetries, and bilateral gynandromorphs, while not figuring prominently in the mainstream work on LR asymmetry, point to crucial and fundamental gaps of knowledge about asymmetry. We identify 12 big questions that provide exciting opportunities for fundamental new advances in this field.

Different gene expressions on the left and the right: a genotype/phenotype mismatch in need of attention

Discordance in monozygotic twins has traditionally been explained in terms of environmental influences. A recent investigation has found a difference in epigenetic markers in older but not in younger twins. However, phenotypic differences that depend on an individual's postnatal life style do not address the problem of discordance in congenital malformations, or the reason why malformations are frequently unilateral, often with a preference for one or the other side. One such condition, cleft lip with or without cleft palate, which is preferentially expressed on the left, is a multifactorial condition, that is caused by a failure of the critical timing necessary for different groups of cells to meet and develop into a normal face. This process is dependent on cell proliferation and migration, which are energy-dependent, while the additional requirement for apoptosis to allow cell fusion suggests the involvement of mitochondria. Recent progress in two separate areas of research could lead to a better understanding of the problem of facial clefts: (1) the recognition of an interaction between gene products and mitochondria in the aetiology of neurodegenerative diseases and (2) the discovery of an increasing number of genes, including transcription factors, growth factors and members of the TGF-beta signalling family, that are differentially expressed on the left and right side, thus pointing to a difference in their micro-environment. These findings emphasize the importance of investigating the activity of candidate genes for complex developmental processes separately on the left and right sides. Data presented in this review suggest that differential growth rates may lead to an inversion of laterality. A method is described to test for a possible mitochondrial difference between left and right sides, using a mouse model with cleft lip.

Cellular heterogeneity during vertebrate skeletal muscle development

Although skeletal muscles appear superficially alike at different anatomical locations, in reality there is considerably more diversity than previously anticipated. Heterogeneity is not only restricted to completely developed fibers, but is clearly apparent during development at the molecular, cellular and anatomical level. Multiple waves of muscle precursors with different features appear before birth and contribute to muscular diversification. Recent cell lineage and gene expression studies have expanded our knowledge on how skeletal muscle is formed and how its heterogeneity is generated. This review will present a comprehensive view of relevant findings in this field.

Cornichon-like protein facilitates secretion of HB-EGF and regulates proper development of cranial nerves

During their migration to the periphery, cranial neural crest cells (NCCs) are repulsed by an ErbB4-dependent cue(s) in the mesenchyme adjoining rhombomeres (r) 3 and 5, which are segmented hindbrain neuromeres. ErbB4 has many ligands, but which ligand functions in the above system has not yet been clearly determined. Here we found that a cornichon-like protein/cornichon homolog 2 (CNIL/CNIH2) gene was expressed in the developing chick r3 and r5. In a cell culture system, its product facilitated the secretion of heparin-binding epidermal growth factor-like growth factor (HB-EGF), one of the ligands of ErbB4. When CNIL function was perturbed in chick embryos by forced expression of a truncated form of CNIL, the distribution of NCCs was affected, which resulted in abnormal nerve fiber connections among the cranial sensory ganglia. Also, knockdown of CNIL or HB-EGF with siRNAs yielded a similar phenotype. This phenotype closely resembled that of ErbB4 knockout mouse embryos. Because HB-EGF was uniformly expressed in the embryonic hindbrain, CNIL seems to confine the site of HB-EGF action to r3 and r5 in concert with ErbB4.

Is the early left-right axis like a plant, a kidney, or a neuron? The integration of physiological signals in embryonic asymmetry

Embryonic morphogenesis occurs along three orthogonal axes. While the patterning of the anterior-posterior and dorsal-ventral axes has been increasingly well-characterized, the left-right (LR) axis has only relatively recently begun to be understood at the molecular level. The mechanisms that ensure invariant LR asymmetry of the heart, viscera, and brain involve fundamental aspects of cell biology, biophysics, and evolutionary biology, and are important not only for basic science but also for the biomedicine of a wide range of birth defects and human genetic syndromes. The LR axis links biomolecular chirality to embryonic development and ultimately to behavior and cognition, revealing feedback loops and conserved functional modules occurring as widely as plants and mammals. This review focuses on the unique and fascinating physiological aspects of LR patterning in a number of vertebrate and invertebrate species, discusses several profound mechanistic analogies between biological regulation in diverse systems (specifically proposing a nonciliary parallel between kidney cells and the LR axis based on subcellular regulation of ion transporter targeting), highlights the possible importance of early, highly-conserved intracellular events that are magnified to embryo-wide scales, and lays out the most important open questions about the function, evolutionary origin, and conservation of mechanisms underlying embryonic asymmetry.