Age-related properties of the tumour vasculature in renal cell carcinoma

Differentiation of Clear Cell and Non-clear-cell Renal Cell Carcinoma through CT-based Radiomics Models and Nomogram

PURPOSE

The aim of the study was to investigate the feasibility of discriminating between clear-cell renal cell carcinoma (ccRCC) and non-clear-cell renal cell carcinoma (non-ccRCC) via radiomics models and nomogram.

METHODS

The retrospective study included 147 patients (ccRCC=100, non-ccRCC=47) who underwent enhanced CT before surgery. CT images of the corticomedullary phase (CMP) were collected and features from the images were extracted. The data were randomly grouped into training and validation sets according to 7:3, and then the training set was normalized to extract the normalization rule for the training set, and then the rule was applied to the validation set. First, the T-test, T'-test or Wilcoxon rank-sum test were executed in the training set data to keep the statistically different parameters, and then the optimal features were picked based on the least absolute shrinkage and selection operator (LASSO) algorithm. Five machine learning (ML) models were trained to differentiate ccRCC from noccRCC, rad+cli nomogram was constructed based on clinical factors and radscore (radiomics score), and the performance of the classifier was mainly measured by area under the curve (AUC), accuracy, sensitivity, specificity, and F1. Finally, the ROC curves and radar plots were plotted according to the five performance parameters.

RESULTS

1130 radiomics features were extracted, there were 736 radiomics features with statistical differences were obtained, and 4 features were finally selected after the LASSO algorithm. In the validation set of this study, three of the five ML models (logistic regression, random forest and support vector machine) had excellent performance (AUC 0.9-1.0) and two models (adaptive boosting and decision tree) had good performance (AUC 0.7-0.9), all with accuracy ≥ 0.800. The rad+cli nomogram performance was found excellent in both the training set (AUC = 0.982,0.963-1.000, accuracy=0.941) and the validation set (AUC = 0.949,0.885-1.000, accuracy=0.911). The random forest model with perfect performance (AUC = 1, accuracy=1) was found superior compared to the model performance in the training set. The rad+cli nomogram model prevailed in the comparison of the model's performance in the validation set.

CONCLUSION

The ML models and nomogram can be used to identify the relatively common pathological subtypes in clinic and provide some reference for clinicians.

Prognosis of clear cell renal cell carcinoma patients stratified by age: A research relied on SEER database

Objective

Clear cell renal cell carcinoma may affect patients of any age. To date, there are only a limited number of large data studies on renal clear cell carcinoma in different age groups. This study assessed CCRCC risk factors in different age groups using the Surveillance Epidemiology and End Results (SEER) database.

Methods

We selected 58372 cases from the SEER database. These patients were divided into seven different age groups. Cox regression models were used to find independent risk factors for the survival of CCRCC patients. Based on independent risk factors, a nomogram was drawn with R software. Kaplan-Meier method for survival analysis and X-tile software were used to find the optimal age group for diagnosis.

Results

Univariate analysis revealed that patients’ age, sex, race, marital status, grade, TNM (tumor, node, metastasis) stage, surgery, WHO/ISUP grade were correlated with survival (P<0.01). Age was an independent risk factor for survival in patients with CCRCC according to multivariate Cox regression analysis (p<0.01). All-cause mortality and tumor-specific mortality increased according to the increasing age of the patients. The optimal cut-off values for age were defined as 58 and 76 years and 51 and 76 years, respectively, according to overall survival (OS) and cause-specific survival (CSS).

Conclusion

There is a negative correlation between age and survival of CCRCC patients. The difference in prognosis of patients in different age groups has important implications for clinical treatment. Therefore, the diagnosis and treatment plan should be based on more detailed age grouping, which is more beneficial to improving the prognosis and survival of patients.

Nomograms for Predicting Overall Survival and Cancer-Specific Survival of Patients With Renal Cell Carcinoma and Venous Tumor Thrombus: A Population-Based Study

Background

To provide better prognostic information for patients with renal cell carcinoma (RCC) combined with venous tumor thrombus (VTT). In turn, guide patients’ families and doctors to formulate plans for follow-up treatment and follow-up. We developed nomograms to predict cancer-specific survival (CSS) and overall survival (OS).

Methods

A total of 2961 cases were included in this study. Through univariate and multivariate Cox proportional hazard regression analysis, independent risk factors affecting CSS and OS were screened out, and then a nomogram was drawn based on the screened variables.

Results

Independent risk factors affecting CSS include: tumor size (HR = 1.05), histology (HR = 1.75), grade (HR = 1.94), N staging (HR = 2.06), and M staging (HR = 2.87). The median survival time for CSS was 106 months. Independent risk factors for OS include age (HR = 1.60), tumor size (HR = 1.04), histology (HR = 1.60), grade (HR = 1.68), N staging (HR-1.99), M staging (HR = 2.45). The median survival time for OS is 67 months.

Conclusions

The nomogram based on independent risk factors affecting CSS and OS can well predict the prognosis of renal cell carcinoma with venous tumor thrombus.

53 years old is a reasonable cut-off value to define young and old patients in clear cell renal cell carcinoma: a study based on TCGA and SEER database

Background

The objectives of this study were to screen out cut-off age value and age-related differentially expressed genes (DEGs) in clear cell renal cell carcinoma (CCRCC) from Surveillance Epidemiology and End Results (SEER) database and The Cancer Genome Atlas (TCGA) database.

Methods

We selected 45,974 CCRCC patients from SEER and 530 RNA-seq data from TCGA database. The age cut-off value was defined using the X-tile program. Propensity score matching (PSM) was used to balance the differences between young and old groups. Hazard ratio (HR) was applied to evaluate prognostic risk of age in different subgroups. Age-related DEGs were identified via RNA-seq data. Survival analysis was used to assess the relationship between DEGs and prognosis.

Results

In this study, we divided the patients into young (n = 14,276) and old (n = 31,698) subgroups according to cut-off value (age = 53). Age > 53 years was indicated as independent risk factor for overall survival (OS) and cancer specific survival (CSS) of CCRCC before and after PSM. The prognosis of old group was worse than that in young group. Eleven gene were differential expression between the younger and older groups in CCRCC. The expression levels of PLA2G2A and SIX2 were related to prognosis of the elderly.

Conclusion

Fifty-three years old was cut-off value in CCRCC. The prognosis of the elderly was worse than young people. It remind clinicians that more attention and better treatment should be given to CCRCC patients who are over 53 years old. PLA2G2A and SIX2 were age-related differential genes which might play an important role in the poor prognosis of elderly CCRCC patients.

Assessing Outcomes and Prognostic Factors for First-Line Therapy in Elderly Patients With Metastatic Renal Cell Carcinoma: Real-Life Data From a Single United Kingdom Institution

BACKGROUND

Elderly metastatic renal cell carcinoma (mRCC) patients are under-represented in clinical trials, whose results are therefore difficult to translate into routine management of older patients. We aimed at exploring treatment outcomes and prognostic factors in our real-life elderly mRCC cohort receiving first-line tyrosine kinase inhibitor (TKI) monotherapy.

PATIENTS AND METHODS

We retrospectively analyzed demographic and clinicopathological characteristics, and treatment data of elderly (≥ 70 years old at first-line start) mRCC patients starting either pazopanib or sunitinib as first-line treatment in our institution between March 2012 and April 2018. Baseline characteristics included age-adjusted Charlson comorbidity index (CCI).

RESULTS

In total, the records of 35 elderly mRCC patients were identified and retrospectively analyzed. Overall response rate, median progression-free survival, and median overall survival were 20%, 9.7 months, and 21.6 months, respectively. Karnofsky performance status ≤ 70%, sarcomatoid features, absolute neutrophil count greater than upper limit of normal, and treatment-related Grade 3 arterial hypertension were independently associated with survival after multivariate analysis. Age-adjusted CCI was significantly associated with survival in univariate analysis only. The overall incidence of Grade 3 to 5 toxicities was 74%. Seven patients (20%) received early crossover to either sunitinib or pazopanib because of toxicity. Dose reduction was applied in 24 (73%) of the 33 patients who completed at least 1 cycle.

CONCLUSION

First-line TKI monotherapy provided clinical benefit in our elderly mRCC cohort. Relatively frequent dose reductions helped to maintain an acceptable tolerability profile. Further research is warranted to explore the significance of prognostic factors in elderly mRCC patients.

Age-related variations in gene expression patterns of renal cell carcinoma

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is known to occur across the adult lifetime traversing the spectrum of age-related organismal changes. Little is known as to how the aging process may affect the course of renal cell carcinoma (RCC) and the repertoire of genes involved.

METHODS

Using The Cancer Genome Atlas (n = 436) and Cancer Genomics of the Kidney (n = 89) datasets, we applied regression analysis to examine associations between patient age and gene expression profiles in ccRCC tumors and normal kidney tissues. Pathway enrichment analysis was performed to identify cellular process that is affected by aging in ccRCC. Moreover, connectivity mapping analysis was used to predict age-dependent response to drug treatments.

RESULTS

Our analysis revealed different age-dependent gene expression spectra in ccRCC and normal kidney tissues. These findings were significant and independently reproducible in both datasets examined. Age up-regulated genes, showing higher expression in older patients, were significantly enriched (false discovery rate <0.05) in normal tissues for pathways associated with immune response and extracellular matrix organization, whereas age up-regulated genes in tumors were enriched for metabolism and oxidation pathways. Strikingly, age down-regulated genes in normal cells were also enriched for metabolism and oxidation, while those in tumors were enriched for extracellular matrix organization. Further in silico analysis of potential drug targets predicted preferential efficacy of Phosphoinositide 3-kinase inhibitor or immunotherapy in association with age.

CONCLUSION

We report on previously unrecognized associations between age and molecular underpinnings of RCC, including age-associated expression of genes implicated in RCC development or treatment.

Efficacy and safety of sunitinib in elderly patients with advanced renal cell carcinoma

Elderly individuals represent a consistent proportion of all cancer patients. However, they are under-represented in clinical trials. The present study evaluated the actual tolerability of sunitinib in elderly Japanese patients with advanced renal cell carcinoma (RCC). A total of 56 consecutive patients with advanced RCC treated with sunitinib were enrolled. Patients were divided into two groups according to their age at the time of sunitinib initiation: i) elderly cohort (≥70 years); and ii) younger cohort (<70 years). Disease control rate, progression-free survival, overall survival and relative dose intensity (RDI) were compared between the two cohorts. The elderly cohort comprised of 14 patients (25.0%), and the younger cohort included 42 patients (75.0%). The elderly cohort had a significantly higher Charlson comorbidity index than the younger cohort (mean, 9.7 vs. 7.9; P<0.0001). Disease control rate, progression-free survival, and overall survival were not significantly different. The elderly cohort had a significantly lower RDI than the younger cohort (mean, 51.7 vs. 65.0%; P=0.0340). Thus, treatment with sunitinib is feasible and effective in elderly Japanese patients with advanced RCC. However, the RDI of elderly patients was significantly lower, and a relatively low dose of sunitinib provided optimal therapeutic efficacy.

Understanding angiogenesis during aging: opportunities for discoveries and new models

Microvascular network growth and remodeling are common denominators for most age-related pathologies. For multiple pathologies (myocardial infarction, stroke, hypertension), promoting microvascular growth, termed angiogenesis, would be beneficial. For others (cancer, retinopathies, rheumatoid arthritis), blocking angiogenesis would be desirable. Most therapeutic strategies, however, are motivated based on studies using adult animal models. This approach is problematic and does not account for the impaired angiogenesis or the inherent network structure changes that might result from age. Considering the common conception that angiogenesis is impaired with age, a need exists to identify the causes and mechanisms of angiogenesis in aged scenarios and for new tools to enable comparison of aged versus adult responses to therapy. The objective of this article is to introduce opportunities for advancing our understanding of angiogenesis in aging through the discovery of novel cell changes along aged microvascular networks and the development of novel ex vivo models.

Resistance to metronomic chemotherapy and ways to overcome it

Therapeutic resistance is amongst the major determinants of cancer mortality. Contrary to initial expectations, antivascular therapies are equally prone to inherent or acquired resistance as other cancer treatment modalities. However, studies into resistance to vascular endothelial growth factor pathway inhibitors revealed distinct mechanisms of resistance compared to conventional cytotoxic therapy. While some of these novel mechanisms of resistance also appear to be functional regarding metronomic chemotherapy, herein we summarize available evidence for mechanisms of resistance specifically described in the context of metronomic chemotherapy. Numerous preclinically identified molecular targets and pathways represent promising avenues to overcome resistance and enhance the benefits achieved with metronomic chemotherapy eventually. However, there are considerable challenges to clinically translate the preclinical findings.

Efficacy and safety of axitinib in elderly patients with metastatic renal cell carcinoma

The objective of this study was to analyze the impact of age on clinical outcomes of metastatic renal cell carcinoma (mRCC) patients receiving axitinib. This study included 144 consecutive mRCC patients who received axitinib for at least 12 weeks as second-line therapy in a routine clinical setting. The efficacy, safety and quality of life (QOL) were compared between patients aged <75 (n = 116) and ≥75 (n = 28) years. No significant differences in the clinicopathological characteristics were noted between younger and older patients. There was no significant difference in the response rate, clinical benefit rate or proportion of patients going on to receive third-line therapy between these two groups. In addition, the progression-free and overall survivals in older patients were similar to those in younger patients. There were no significant differences in the incidences of adverse events between these two groups, except for that of fatigue, which was significantly more frequent in older than younger patients. There was no significant difference in the incidence of the discontinuation of axitinib due to adverse events between the two groups. QOL assessment at 12 weeks after the introduction of axitinib using the Medical Outcomes Study 36-Item Short Form showed no significant differences in any of the eight scale scores between the two groups. Taken together, it might be possible to achieve clinical outcomes in older patients receiving axitinib comparable to those in younger patients, suggesting that advanced age should not be a contraindication to treatment with axitinib as a second-line setting in mRCC patients.

Treatment of elderly patients with metastatic renal cell carcinoma

The risk of developing renal cell carcinoma (RCC) increases with age, and given the constant gain in life expectancy of the general population, both localized RCC and metastatic RCC (mRCC) are more frequently observed in the elderly population. The elderly are a heterogeneous group of patients often characterized by the presence of comorbidities, different compliance to treatment and polypharmacy. Here we review the available data with the aim to analyze the safety and efficacy of new targeted therapies (TTs) in elderly mRCC patients. TTs seem to be effective in both older and younger patients, but elderly patients appear to show reduced tolerance to treatments compared to younger patients. Prospective trials are needed to better understand how to manage mRCC in elderly patients.

Studies on the Tumor Vasculature and Coagulant Microenvironment

Angiogenesis represents one aspect in the complex process that leads to the generation of the vascular tumor stroma. The related functional constituents include responses of endothelial, mural, bone marrow-derived, and resident inflammatory cells as well as activation of coagulation and fibrinolytic systems in blood. Multiple molecular and cellular effectors participate in these events, often in a tumor-specific manner and with changes enforced through the microenvironment, genetic evolution, and responses to anticancer therapies. To capture various elements of these interactions several surrogate assays have been devised, which can be mechanistically useful and are amenable to quantification, but are individually insufficient to describe the underlying complexity and are best used in a targeted and combinatorial manner. Below, we present a survey of angiogenesis assays and experimental approaches to analyze vascular events in cancer. We also provided specific examples of validated protocols, which are less described, but enable the straightforward analysis of vascular structures and coagulant properties of cancer cells in vivo and in vitro.

Clinical outcome of advanced and metastatic renal cell carcinoma treated with targeted therapy: is there a difference between young and old patients?

Background

To assess whether the clinical outcome of advanced and metastatic renal cell carcinoma (mRCC) treated with targeted therapy differs between young and old patients.

Patients and methods

A total of 327 patients with advanced renal cell carcinoma and mRCC who received targeted therapy in two Chinese clinical centers were analyzed retrospectively. The patients were stratified into three groups: young (aged <45 years), middle-aged (aged 45–64 years), and old (aged ≥65 years). Overall survival (OS) and progression-free survival (PFS) curves were drawn using the Kaplan–Meier method, and Cox’s proportional hazard regression model was used to compare OS and PFS within age groups.

Results

There were no significant differences among young, middle-aged, and old groups in terms of OS (P=0.087), whereas PFS in the old group was significantly better than in the young and middle-aged groups (P=0.043). Both OS and PFS in the younger groups (aged <65 years) were significantly worse than in the old group (age ≥65 years; median OS, 28.1 vs 28.7 months [P=0.029]; median PFS, 11.4 vs 14 months [P=0.015]). No difference in OS or PFS was found between the young and middle-aged groups. After adjusting for sex, body mass index, smoking status, hypertension, diabetes mellitus, Eastern Cooperative Oncology Group score, history of cytokines, and Fuhrman grade, old age was an independent favorable prognostic factor for OS and PFS compared with younger age (<65 years) (OS, hazard ratio, 0.552 [95% confidence interval, 0.329–0.828; P=0.006]; PFS, hazard ratio, 0.584 [95% confidence interval, 0.401–0.850; P=0.005]).

Conclusion

Younger patients with advanced renal cell carcinoma and mRCC receiving targeted therapy have a poorer prognosis compared with old patients. These results remain to be examined in prospective cohorts.

Ageing-related responses to antiangiogenic effects of sunitinib in atherosclerosis-prone mice

Antiangiogenic therapies in cancer exert their effects in the context of age-related comorbidities, which affect the entirety of the vascular system. Among those conditions, the impact of atherosclerosis is especially prevalent, but poorly understood, and not reflected in mouse models routinely used for testing antiangiogenic therapeutics. Our earlier work suggested that these obstacles can be overcome with the use of atherosclerosis-prone ApoE-/- mice harbouring syngeneic transplantable Lewis Lung Carcinoma (LLC). Here we report that, sunitinib, the clinically approved, antiangiogenic inhibitor impedes global tumor growth to a greater extent in aged then in young mice. This activity was coupled with changes in the tumor microenvironment, which in aged mice was characterized by pronounced hypoxia, reduction in microvascular density (MVD) and lower pericyte coverage, relative to young controls. We also detected soluble VEGR2 in plasma of sunitinib treated mice. Interestingly, sunitinib modulated tumor infiltration with bone marrow-derived cells (CD45+), recruitment of M2-like macrophages (CD163+) and activation of inflammatory pathways (phospho-STAT3) in a manner that was age-dependent. We suggest that age and atherosclerosis may alter the effects of sunitinib on the tumor microenvironment, and that these considerations may also apply more broadly to other forms of antiangiogenic treatment in cancer.

Efficacy and safety of sunitinib in elderly patients with metastatic renal cell carcinoma

Background:

We retrospectively analyzed sunitinib outcome as a function of age in metastatic renal cell carcinoma (mRCC) patients.

Methods:

Data were pooled from 1059 patients in six trials. Kaplan–Meier estimates of progression-free survival (PFS) and overall survival (OS) were compared by log-rank test between patients aged <70 (n=857; 81%) and ⩾70 (n=202; 19%) years.

Results:

In first-line patients, median PFS was comparable in younger and older patients, 9.9 vs 11.0 months, respectively (HR, 0.89; 95% CI: 0.73–1.09; P=0.2629), as was median OS, 23.6 vs 25.6 months (HR, 0.93; 95% CI: 0.74–1.18; P=0.5442). Similarly, in cytokine-refractory patients, median PFS was 8.1 vs 8.4 months (HR, 0.79; 95% CI: 0.49–1.28; P=0.3350), while median OS was 20.2 vs 15.8 months (HR, 1.14; 95% CI: 0.73–1.79; P=0.5657). Some treatment-emergent adverse events were significantly less common in younger vs older patients, including fatigue (60% vs 69%), cough (20% vs 29%), peripheral edema (17% vs 27%), anemia (18% vs 25%), decreased appetite (13% vs 29%), and thrombocytopenia (16% vs 25% all P<0.05). Hand–foot syndrome was more common in younger patients (32% vs 24%).

Conclusions:

Advanced age should not be a deterrent to sunitinib therapy and elderly patients may achieve additional clinical benefit.

Expression of follicle-stimulating hormone receptor by the vascular endothelium in tumor metastases

Background

The Follicle Stimulating Hormone receptor (FSHR) is expressed by the vascular endothelium in a wide range of human tumors. It was not determined however if FSHR is present in metastases which are responsible for the terminal illness.

Methods

We used immunohistochemistry based on a highly FSHR-specific monoclonal antibody to detect FSHR in cancer metastases from 6 major tumor types (lung, breast, prostate, colon, kidney, and leiomyosarcoma ) to 6 frequent locations (bone, liver, lymph node, brain, lung, and pleura) of 209 patients.

Results

In 166 patients examined (79%), FSHR was expressed by blood vessels associated with metastatic tissue. FSHR-positive vessels were present in the interior of the tumors and some few millimeters outside, in the normally appearing tissue. In the interior of the metastases, the density of the FSHR-positive vessels was constant up to 7 mm, the maximum depth available in the analyzed sections. No significant differences were noticed between the density of FSHR-positive vessels inside vs. outside tumors for metastases from lung, breast, colon, and kidney cancers. In contrast, for prostate cancer metastases, the density of FSHR-positive vessels was about 3-fold higher at the exterior of the tumor compared to the interior. Among brain metastases, the density of FSHR-positive vessels was highest in lung and kidney cancer, and lowest in prostate and colon cancer. In metastases of breast cancer to the lung pleura, the percentage of blood vessels expressing FSHR was positively correlated with the progesterone receptor level, but not with either HER-2 or estrogen receptors. In normal tissues corresponding to the host organs for the analyzed metastases, obtained from patients not known to have cancer, FSHR staining was absent, with the exception of approx. 1% of the vessels in non tumoral temporal lobe epilepsy samples.

Conclusion

FSHR is expressed by the endothelium of blood vessels in the majority of metastatic tumors.

Impact of host ageing on the metastatic phenotype

Ageing impacts multiple host mechanisms involved in cancer progression. Here we show that poorly metastatic Lewis lung carcinoma (LLC) cells form less bulky metastatic deposits in aged mice (>52 weeks) relative to their young (4-6 weeks) counterparts. Serial selection of LLC cells for increased metastatic capability in either young or old mice led in both cases to exaggerated growth of pulmonary nodules after only 5 cycles of in vivo passage. The respective metastatic cellular variants established in young (Y-series) or old (O-series) mice differed in cell morphology and constitutive activity of growth factor receptors, especially phospho-PDGFRa and phospho-EPHA7. These cell lines also exhibited marked differences in their time dependent profiles of cellular impedance (CI), which reflects their physical properties, such as cell shape, adhesion and interactions with substrata. In confluent monolayer culture Y-series cell lines generated high and increasing CI values, while these values remained low and constant in the O-series of cell lines. These observations suggest that the selective pressure of the metastatic microenvironment in young versus old hosts is sufficiently different to results in the enrichment of distinct, age-related metastatic phenotypes of cancer cells. Thus, age could inform therapeutic approaches to metastatic cancers.

Tumor endothelial marker 7 (TEM-7): a novel target for antiangiogenic therapy

Antiangiogenesis has been validated as a therapeutic strategy to treat cancer, however, a need remains to identify new targets and therapies for specific diseases and to improve clinical benefit from antiangiogenic agents. Tumor endothelial marker 7 (TEM-7) was investigated as a possible target for therapeutic antiangiogenic intervention in cancer. TEM-7 expression was assessed by in situ hybridization or by immunohistochemistry (IHC) in 130 formalin-fixed paraffin-embedded (FFPE) and 410 frozen human clinical specimens of cancer plus 301 normal tissue samples. In vitro TEM-7 expression was evaluated in 4 human endothelial cell models and in 32 human cancer cell lines by RT-PCR and flow cytometry. An anti-TEM-7 antibody was tested in vitro on human SKOV3 ovarian and MDA-MB-231 breast carcinoma cells that expressed TEM-7 in antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis assays. In frozen tumor tissues, TEM-7 mRNA and protein was detected in all but one of the cancer types tested and was infrequently expressed in normal frozen tissues. In FFPE tumor tissues, TEM-7 protein was detected by IHC in colon, breast, lung, bladder, ovarian and endometrial cancers and in sarcomas. TEM-7 protein was not detected in head and neck, prostate or liver cancers. TEM-7 expression was restricted to the vasculature and was absent from tumor cells. In vitro, TEM-7 was not detected in human microvascular endothelial cells (HMVEC) or human umbilical vein endothelial cells (HUVEC) but was induced in endothelial precursor/progenitor cells (EPC) in the presence of the mitogen phorbol ester PMA. An anti-TEM-7 antibody mediated ADCC and phagocytosis in SKOV3 and MDA-MB-231 cell lines infected with an adenovirus expressing TEM-7. These data demonstrate that TEM-7 is a vascular protein associated with angiogenic states. TEM-7 is a novel and attractive target for antiangiogenic therapy.

Notch in the kidney: development and disease

Notch signalling is a highly conserved cell-cell communication mechanism that regulates development, tissue homeostasis, and repair. Within the kidney, Notch has an important function in orchestrating kidney development. Recent studies indicate that Notch plays a key role in establishing proximal epithelial fate during nephron segmentation as well as the differentiation of principal cells in the renal collecting system. Notch signalling is markedly reduced in the adult kidney; however, increased Notch signalling has been noted in both acute and chronic kidney injury. Increased glomerular epithelial Notch signalling has been associated with albuminuria and glomerulosclerosis, while tubular epithelial Notch activation caused fibrosis development most likely inducing an improper epithelial repair pathway. Recent studies thereby indicate that Notch is a key regulator of kidney development, repair, and injury.