Caveolin-1 and breast cancer: a new clinical perspective

Integrated meta-analyses of genome-wide effects of PM2.5 in human cells identifies widespread dysregulation of genes and pathways associated with cancer progression and patient survival

Epidemiological studies have consistently shown a positive association between exposure to ambient PM2.5, a major component of air pollution, and various types of cancer. Previous biological research has primarily focused on the association between PM2.5 and lung cancer, with limited investigation into other cancer types. In this study, we conducted a meta-analysis on multiple PM2.5-treated normal human cell lines to identify potential molecular targets and pathways of PM2.5. Our analysis revealed 310 common differentially expressed genes (DEGs) that exhibited significant dysregulation upon exposure to PM2.5. These dysregulated genes covered a diverse range of functional categories, including oncogenes, tumor suppressor genes, and immune-related genes, which collectively contribute to PM2.5-induced carcinogenesis. Pathway enrichment analysis revealed the up-regulation of pathways associated with HIF-1, VEGF, and MAPK signalling, all of which have been implicated in various cancers. Induction in the levels of HIF pathway genes (HIF1⍺, HIF2⍺, VEGFA, BNIP3, EPO and PGK1) upon PM2.5 treatment was also confirmed by qRT-PCR. Furthermore, the construction of a protein-protein interaction (PPI) network unveiled hub genes, such as NQO1 and PDGFRB, that are known to be dysregulated and significantly correlated with overall survival in lung and breast cancer patients, suggesting their potential clinical significance. This study provides a deep insight into how PM2.5-mediated dysregulation of oncogenes or tumor suppressor genes across various human tissues may play an important role in PM2.5-induced carcinogenesis. Further exploration of these dysregulated molecular targets may enhance our understanding of the biological effects of PM2.5 and facilitate the development of preventive strategies and targeted therapies for PM2.5-associated cancers.

The Metabolic Landscape of Breast Cancer and Its Therapeutic Implications

Breast cancer is the most common malignant tumor globally as of 2020 and remains the second leading cause of cancer-related death among female individuals worldwide. Metabolic reprogramming is well recognized as a hallmark of malignancy owing to the rewiring of multiple biological processes, notably, glycolysis, oxidative phosphorylation, pentose phosphate pathway, as well as lipid metabolism, which support the demands for the relentless growth of tumor cells and allows distant metastasis of cancer cells. Breast cancer cells are well documented to reprogram their metabolism via mutations or inactivation of intrinsic factors such as c-Myc, TP53, hypoxia-inducible factor, and the PI3K/AKT/mTOR pathway or crosstalk with the surrounding tumor microenvironments, including hypoxia, extracellular acidification and interaction with immune cells, cancer-associated fibroblasts, and adipocytes. Furthermore, altered metabolism contributes to acquired or inherent therapeutic resistance. Therefore, there is an urgent need to understand the metabolic plasticity underlying breast cancer progression as well as to dictate metabolic reprogramming that accounts for the resistance to standard of care. This review aims to illustrate the altered metabolism in breast cancer and its underlying mechanisms, as well as metabolic interventions in breast cancer treatment, with the intention to provide strategies for developing novel therapeutic treatments for breast cancer.

Cholesterol-enriched membrane micro-domaindeficiency induces doxorubicin resistancevia promoting autophagy in breast cancer

Drug resistance has become one of the largest challenges for cancer chemotherapies. Under certain conditions, cancer cells hijack autophagy to cope with therapeutic stress, which largely undermines the chemo-therapeutic efficacy. Currently, biomarkers indicative of autophagy-derived drug resistance remain largely inclusive. Here, we report a novel role of lipid rafts/cholesterol-enriched membrane micro-domains (CEMMs) in autophagosome biogenesis and doxorubicin resistance in breast tumors. We showed that CEMMs are required for the interaction of VAMP3 with syntaxin 6 (STX6, a cholesterol-binding SNARE protein). Upon disruption of CEMM, VAMP3 is released from STX6, resulting in the trafficking of ATG16L1-containing vesicles to recycling endosomes and subsequent autophagosome biogenesis. Furthermore, we found that CEMM marker CAV1 is decreased in breast cancer patients and that the CEMM deficiency-induced autophagy is related to doxorubicin resistance, which is overcome by autophagy inhibition. Taken together, we propose a novel model whereby CEMMs in recycling endosomes support the VAMP3 and STX6 interaction and function as barriers to limit the activity of VAMP3 in autophagic vesicle fusion, thus CEMM deficiency promotes autophagosome biogenesis and doxorubicin resistance in breast tumors.

Caveolin-1: A promising therapeutic target for diverse diseases

The plasma membrane of eukaryotic cells contains small flask-shaped invaginations known as caveolae that are involved in the regulation of cellular signaling. Caveolin-1 is a 21-24kDa protein localized in the caveolar membrane. Caveolin-1 (Cav-1) has been considered as a master regulator among the various signaling molecules. It has been emerging as a chief protein regulating cellular events associated with homeostasis, caveolae formation, and caveolae trafficking. In addition to the physiological role of cav-1, it has a complex role in the progression of various diseases. Caveolin-1 has been identified as a prognosticator in patients with cancer and has a dual role in tumorigenesis. The expression of Cav-1 in hippocampal neurons and synapses is related to neurodegeneration, cognitive decline, and aging. Despite the ubiquitous association of caveolin-1 in various pathological processes, the mechanisms associated with these events are still unclear. Caveolin-1 has a significant role in various events of the viral cycle, such as viral entry. This review will summarize the role of cav-1 in the development of cancer, neurodegeneration, glaucoma, cardiovascular diseases, and infectious diseases. The therapeutic perspectives involving clinical applications of Caveolin-1 have also been discussed. The understanding of the involvement of caveolin-1 in various diseased states provides insights into how it can be explored as a novel therapeutic target.

Essential role of STAT5a in DCIS formation and invasion following estrogen treatment

Ductal carcinoma in situ (DCIS) is one of the earliest stages of breast cancer (BCa). The mechanisms by which DCIS lesions progress to an invasive state while others remain indolent are yet to be fully characterized and both diagnosis and treatment of this pre-invasive disease could benefit from better understanding the pathways involved. While a decreased expression of Caveolin-1 (Cav-1) in the tumor microenvironment of patients with DCIS breast cancer was linked to progression to invasive breast cancer (IBC), the downstream effector(s) contributing to this process remain elusive. The current report shows elevated expression of Signal Transducer and Activator of Transcription 5a (STAT5a) within the DCIS-like lesions in Cav-1 KO mice following estrogen treatment and inhibition of STAT5a expression prevented the formation of these mammary lesions. In addition, STAT5a overexpression in a human DCIS cell line (MCF10DCIS.com) promoted their invasion, a process accelerated by estrogen treatment and associated with increased levels of the matrix metalloproteinase-9 (MMP-9) precursor. In sum, our results demonstrate a novel regulatory axis (Cav-1♦STAT5a♦MMP-9) in DCIS that is fully activated by the presence of estrogen. Our sudies suggest to further study phosphorylated STAT5a (Y694) as a potential biomarker to guide and predict outcome of DCIS patient population.

Apolipoprotein-mediated regulation of lipid metabolism induces distinctive effects in different types of breast cancer cells

BACKGROUND

The highest incidence of breast cancer is in the Western world. Several aspects of the Western lifestyle are known risk factors for breast cancer. In particular, previous studies have shown that cholesterol levels can play an important role in the regulation of tumor progression.

METHODS

In the present study, we modulated cholesterol metabolism in the human breast cancer cell lines MCF-7 and MDA-MB-231 using a genetic approach. Apolipoprotein A-I (apoA-I) and apolipoprotein E (apoE) were expressed in these cell lines to modulate cholesterol metabolism. The effects of these apolipoproteins on cancer cell properties were examined.

RESULTS

Our results show that both apolipoproteins can regulate cholesterol metabolism and can control the epithelial-to-mesenchymal transition process. However, these effects were different depending on the cell type. We show that expressing apoA-I or apoE stimulates proliferation, migration, and tumor growth of MCF-7 cells. However, apoA-I or apoE reduces proliferation and migration of MDA-MB-231 cells.

CONCLUSIONS

These data suggest that modulating sterol metabolism may be most effective at limiting tumor progression in models of triple-negative cancers.

Association of CAV1 polymorphisms with the risks of breast cancer: A systematic review and meta-analysis

BACKGROUND

Caveolin-1 (CAV1) polymorphisms have been shown to correlated with breast cancer risk in previous studies. However, the role of CAV1 polymorphisms still remained indecisive, and dual functions of CAV1 was demonstrated in breast cancer development. Consequently, a meta-analysis to evaluate and summarize the association of the CAV1 polymorphisms with breast cancer susceptibility.

MATERIAL AND METHODS

Extensive search was performed in PubMed, Web of Science, Google scholar, EMBASE.com, CNKI and Wanfang searching platform up to March 2019. The Newcastle-Ottawa Scale (NOS) were used to evaluate the quality of each study. The Odds ratios (ORs) and the 95% confidence intervals (CIs) were analyzed to evaluate the strength of the associations in five genetic models. Inter-study heterogeneity was quantified using the I-squared (I²) test. In addition, the Egger's test and Begg's test were applied to evaluate the publication bias.

RESULTS

4 case-control studies with 2115 cases and 2138 controls were enrolled into this analysis. There was a significant association between rs3807987 polymorphism of CAV1 and breast cancer in allele comparison (A vs. G: OR = 1.288, 95％CI = 1.162-1.428, P < 0.001), heterozygote comparison (AG vs. GG: OR= 1.422, 95％CI=1.233-1.639, P < 0.001), and dominant comparison (AA+AG vs. GG: OR=1.395, 95％CI=1.228-1.586, P < 0.001). A significant association of rs3807987 polymorphism in allele comparison (A vs. G: OR=1.238, 95％CI=1.109-1.383, P < 0.001), heterozygote comparison (AG VS. GG: OR=1.466, 95％CI=1.267-1.697, P < 0.05), and dominant comparison (AA+AG vs. GG: OR=1.384, 95％CI=1.209-1.585, P < 0.001) was also founded amongst Chinese population. A significant association between rs7804372 polymorphism and breast cancer amongst Chinese population in recessive comparison (AA vs. AT + TT: OR = 0.730, 95％CI = 0.567-0.940, P = 0.015) was identified. No significant association between breast cancer risk and rs1997623 was found.

CONCLUSION

CAV1 rs3807987 and rs7804372 polymorphisms are associated with the change of breast cancer risk. More well-designed and large studies in various populations are needed to further elaborate these associations.

Caveolin-1: a multifaceted driver of breast cancer progression and its application in clinical treatment

Human breast cancer is one of the most frequent cancer diseases and causes of death among female population worldwide. It appears at a high incidence and has a high malignancy, mortality, recurrence rate and poor prognosis. Caveolin-1 (Cav1) is the main component of caveolae and participates in various biological events. More and more experimental studies have shown that Cav1 plays a critical role in the progression of breast cancer including cell proliferation, apoptosis, autophagy, invasion, migration and breast cancer metastasis. Besides, Cav1 has been found to be involved in chemotherapeutics and radiotherapy resistance, which are still the principal problems encountered in clinical breast cancer treatment. In addition, stromal Cav1 may be a potential indicator for breast cancer patients' prognosis. In the current review, we cover the state-of-the-art study, development and progress on Cav1 and breast cancer, altogether describing the role of Cav1 in breast cancer progression and application in clinical treatment, in the hope of providing a basis for further research and promoting CAV1 gene as a potential target to diagnose and treat aggressive breast cancers.

Tubeimoside V sensitizes human triple negative breast cancer MDA-MB-231 cells to anoikis via regulating caveolin-1-related signaling pathways

Metastatic triple-negative breast cancer (TNBC) has poor outcome with conventional chemotherapy regimens due to its aggressive behavior. The acquisition of anoikis resistance, a programmed cell death process triggered by substratum detachment, is an important mechanism in TNBC metastasis. Therefore, agents that can restore the sensitivity of cancer cells to anoikis may be helpful for the treatment of metastatic TNBC. In this study, we investigated the inhibitory effect of Tubeimosides V (TBMS-V), a cyclic bisdesmoside isolated from the ethanol extracts of tubers of B. paniculatum., on anoikis resistance and the involvement of caveolin-1(CAV-1)-related signaling pathways in such process in MDA-MB-231 cells. The results showed that the treatment of TBMS-V could sensitize cancer cells to anoikis, which was associated with suppression of anchorage-independent culture-induced CAV-1 overexpression, EGFR activation as well as ITGB1-FAK activation. The data from this study might contribute to providing a potential therapeutic target for metastatic TNBC and suggest the possibility of TBMS-V and its derivatives for metastatic TNBC therapy.

Caveolin-1, a stress-related oncotarget, in drug resistance

Caveolin-1 (Cav-1) is both a tumor suppressor and an oncoprotein. Cav-1 overexpression was frequently confirmed in advanced cancer stages and positively associated with ABC transporters, cancer stem cell populations, aerobic glycolysis activity and autophagy. Cav-1 was tied to various stresses including radiotherapy, fluid shear and oxidative stresses and ultraviolet exposure, and interacted with stress signals such as AMP-activated protein kinase. Finally, a Cav-1 fluctuation model during cancer development is provided and Cav-1 is suggested to be a stress signal and cytoprotective. Loss of Cav-1 may increase susceptibility to oncogenic events. However, research to explore the underlying molecular network between Cav-1 and stress signals is warranted.

Her2 and Ki67 Biomarkers Predict Recurrence of Ductal Carcinoma in Situ

BACKGROUND

A subset of patients with ductal carcinoma in situ (DCIS) experience recurrence or progression to invasive cancer. Current clinical practice is not reliably guided by DCIS recurrence prediction, although recurrence risk for invasive breast cancer can now be assessed. We analyzed a panel of biomarkers (estrogen receptor, Her2, Ki67, p53, cyclin D1, COX-2, caveolin-1, survivin, and PPAR-γ) and DCIS histologic and clinical features to determine associations with DCIS recurrence.

MATERIALS AND METHODS

Seventy DCIS cases diagnosed between 1995 and 2010 were divided into 2 groups: 52 had DCIS without known recurrence after excision and 18 had DCIS with subsequent recurrence after excision as DCIS or invasive carcinoma in the ipsilateral or contralateral breast. Tissue microarrays were prepared, immunohistochemistry performed, and expression of the biomarkers scored semiquantitatively. Variables analyzed included age, tumor size, margin status, DCIS grade, necrosis, histologic type, and immunohistochemistry scores. Differences between groups were evaluated using t tests for continuous variables and Fisher exact tests for categorical variables.

RESULTS

Intraductal necrosis was associated with increased recurrence risk: 46% of nonrecurrent cases showed necrosis compared with 83% of those who recurred (P=0.007). Her2 (human epidermal growth factor receptor 2) and Ki67 expression distributions were significantly different between nonrecurrent and recurrent cases. Her2 was overexpressed in 14% of nonrecurrent cases compared with 50% in the recurrent cases (P=0.03). A total of 87% of nonrecurrent cases had low Ki67 staining (0% to 10%) compared with 50% among the recurrent cases (P=0.002).

CONCLUSION

Our results suggest that Her2 and Ki67 immunohistochemistry and the presence of intraductal necrosis aid in DCIS risk stratification.

Caveolin-1 in Breast Cancer: Single Molecule Regulation of Multiple Key Signaling Pathways

Caveolin-1 is a 22-kD trans-membrane protein enriched in particular plasma membrane invaginations known as caveolae. Cav-1 expression is often dysregulated in human breast cancers, being commonly upregulated in cancer cells and downregulated in stromal cells. As an intracellular scaffolding protein, Cav-1, is involved in several vital biological regulations including endocytosis, transcytosis, vesicular transport, and signaling pathways. Several pathways are modulated by Cav-1 including estrogen receptor, EGFR, Her2/neu, TGFβ, and mTOR and represent as major drivers in mammary carcinogenesis. Expression and role of Cav-1 in breast carcinogenesis is highly variable depending on the stage of tumor development as well as context of the cell. However, recent data have shown that downregulation of Cav-1 expression in stromal breast tumors is associated with frequent relapse, resistance to therapy, and poor outcome. Modification of Cav-1 expression for translational cancer therapy is particularly challenging since numerous signaling pathways might be affected. This review focuses on present understanding of Cav-1 in breast carcinogenesis and its potential role as a new biomarker for predicting therapeutic response and prognosis as well as new target for therapeutic manipulation.

Caveolin-1 mediates inflammatory breast cancer cell invasion via the Akt1 pathway and RhoC GTPase

With a propensity to invade the dermal lymphatic vessels of the skin overlying the breast and readily metastasize, inflammatory breast cancer (IBC) is arguably the deadliest form of breast cancer. We previously reported that caveolin-1 is overexpressed in IBC and that RhoC GTPase is a metastatic switch responsible for the invasive phenotype. RhoC-driven invasion requires phosphorylation by Akt1. Using a reliable IBC cell line we set out to determine if caveolin-1 expression affects RhoC-mediated IBC invasion. Caveolin-1 was down regulated by introduction of siRNA or a caveolin scaffolding domain. The ability of the cells to invade was tested and the status of Akt1 and RhoC GTPase examined. IBC cell invasion is significantly decreased when caveolin-1 is down regulated. Activation of Akt1 is decreased when caveolin-1 is down regulated, leading to decreased phosphorylation of RhoC GTPase. Thus, we report here that caveolin-1 overexpression mediates IBC cell invasion through activation Akt1, which phosphorylates RhoC GTPase.

CAVEOLIN-1 expression in brain metastasis from lung cancer predicts worse outcome and radioresistance, irrespective of tumor histotype

Brain metastases develop in one-third of patients with non-small-cell lung cancer and are associated with a dismal prognosis, irrespective of surgery or chemo-radiotherapy. Pathological markers for predicting outcomes after surgical resection and radiotherapy responsiveness are still lacking. Caveolin 1 has been associated with chemo- and radioresistance in various tumors, including non-small-cell lung cancer. Here, caveolin 1 expression was assessed in a series of 69 brain metastases from non-small-cell lung cancer and matched primary tumors to determine its role in predicting survival and radiotherapy responsiveness. Only caveolin 1 expression in brain metastasis was associated with poor prognosis and an increased risk of death (log rank test, p = 0.015). Moreover, in the younger patients (median age of <54 years), caveolin 1 expression neutralized the favorable effect of young age on survival compared with the older patients. Among the radiotherapy-treated patients, an increased risk of death was detected in the group with caveolin 1-positive brain metastasis (14 out of 22 patients, HR=6.839, 95% CI 1.849 to 25.301, Wald test p = 0.004). Overall, caveolin 1 expression in brain metastasis from non-small-cell lung cancer is independently predictive of worse outcome and radioresistance and could become an additional tool for personalized therapy in the critical subset of brain-metastatic non-small-cell lung cancer patients.

Caveolin-1 Dependent Endocytosis Enhances the Chemosensitivity of HER-2 Positive Breast Cancer Cells to Trastuzumab Emtansine (T-DM1)

The humanized monoclonal antibody-drug conjugate trastuzumab emtansine (T-DM1, Kadcyla) has been approved by the U.S. FDA to treat human epidermal growth factor receptor 2 (HER-2)-positive metastatic breast cancer. Despite its effectiveness in most patients, some are initially resistant or develop resistance. No biomarker of drug resistance to T-DM1 has been identified. Antibody-drug efficacy is associated with antibody internalization in the cell; therefore, cellular sensitivity of cells to the drug may be linked to cellular vesicle trafficking systems. Caveolin-1 is a 22 KD protein required for caveolae formation and endocytic membrane transport. In this study, the relationship between caveolin-1 expression and the chemosensitivity of HER-2-positive breast cancer cells to T-DM1 was investigated. Samples from 32 human breast cancer biopsy and normal tissue specimens were evaluated immunohistochemically for caveolin-1 expression. Caveolin-1 was shown to be expressed in 68% (22/32) of the breast cancer specimens. In addition, eight (72.7%, 8/11) HER-2 positive breast cancer specimens had a higher caveolin-1 expression than normal tissues. HER-2-positive BT-474 and SKBR-3 breast cancer cells that express low and moderate levels of caveolin-1, respectively, were treated with trastuzumab or its conjugate T-DM1. Cell viability and molecular localizations of caveolin-1, antibody and its conjugate were examined. Confocal microscopy showed that T-DM1 and caveolin-1 colocalized in SKBR-3 cells, which also were five times more sensitive to the conjugate in terms of cell survival than BT-474 cells, although T-DM1 also showed improved drug efficacy in BT-474 cells than trastuzumab treatment. Caveolin-1 expression in these lines was manipulated by transfection of GFP-tagged caveolin-1 or caveolin-1 siRNA. BT-474 cells overexpressing caveolin-1 were more sensitive to T-DM1 treatment than mock-transfected cells, whereas the siRNA-transfected SKBR-3 cells had decreased sensitivity to T-DM1 than mock-transfected SKBR-3 cells. The expression of caveolin-1 could mediate endocytosis and promote the internalization of T-DM1 into HER-2 positive cancer cells. Thus, caveolin-1 protein may be an effective predictor for determining the outcome of T-DM1 treatment in breast cancer patients.

The importance of Src signaling in sarcoma

Src is a tyrosine kinase that is of significance in tumor biology. The present review focuses on Src, its molecular structure, and role in cancer, in addition to its expression and function in sarcoma. In addition, the feasibility of Src as a potential drug target for the treatment of sarcoma is also discussed. Previous studies have suggested that Src has essential functions in cell proliferation, apoptosis, invasion, metastasis and the tumor microenvironment. Thus, it may be a potential target for cancer therapy. Src has been found to enhance proliferation, reduce apoptosis and promote metastasis in certain subtypes of sarcoma, including osteosarcoma, chondrosarcoma and Ewing's sarcoma. Furthermore, a number of novel effective therapeutic agents, such as SI-83, which target Src have been investigated in vitro and in vivo. Bosutinib and dasatinib, which inhibit Src, have been approved by the U.S. Food and Drug Administration for the treatment of chronic myelogenous leukemia. In addition, vandetanib is approved for the treatment of medullary thyroid cancer. Furthermore, the Src inhibitor, saracatinib, is currently in clinical trials for the treatment of a variety of solid tumors, including breast and lung cancers. Thus, Src is considered to be an important factor in sarcoma progression and may present a novel clinical therapeutic target. This review demonstrates the importance and clinical relevance of Src in sarcoma, and discusses a number of small molecular inhibitors of src kinase, such as dasatinib and sarcatinib, which are currently in clinical trials for the treatment of sarcoma patients.

Oxidative stress induces caveolin 1 degradation and impairs caveolae functions in skeletal muscle cells

Increased level of oxidative stress, a major actor of cellular aging, impairs the regenerative capacity of skeletal muscle and leads to the reduction in the number and size of muscle fibers causing sarcopenia. Caveolin 1 is the major component of caveolae, small membrane invaginations involved in signaling and endocytic trafficking. Their role has recently expanded to mechanosensing and to the regulation of oxidative stress-induced pathways. Here, we increased the amount of reactive oxidative species in myoblasts by addition of hydrogen peroxide (H₂O₂) at non-toxic concentrations. The expression level of caveolin 1 was significantly decreased as early as 10 min after 500 μM H₂O₂ treatment. This reduction was not observed in the presence of a proteasome inhibitor, suggesting that caveolin 1 was rapidly degraded by the proteasome. In spite of caveolin 1 decrease, caveolae were still able to assemble at the plasma membrane. Their functions however were significantly perturbed by oxidative stress. Endocytosis of a ceramide analog monitored by flow cytometry was significantly diminished after H₂O₂ treatment, indicating that oxidative stress impaired its selective internalization via caveolae. The contribution of caveolae to the plasma membrane reservoir has been monitored after osmotic cell swelling. H₂O₂ treatment increased membrane fragility revealing that treated cells were more sensitive to an acute mechanical stress. Altogether, our results indicate that H₂O₂ decreased caveolin 1 expression and impaired caveolae functions. These data give new insights on age-related deficiencies in skeletal muscle.

The role of oxidized ATM in the regulation of oxidative stress-induced energy metabolism reprogramming of CAFs

Cancer-associated fibroblasts (CAFs) are the predominant cell type in tumor microenvironment (TM) and featured with the distinct energy metabolism reprogramming (EMR) phenotype caused by many factors such as hypoxia and growth factors. The EMR of CAFs plays a key role in biological behaviors of cancer cells including proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT). Recently, accumulative evidence indicates that oxidative stress (OS) mediates the EMR of CAFs under conditions of various stimuli. However, the precise mechanism by which OS causes the EMR of CAFs is not clear. Interestingly, our previous work suggested that ataxia-telangiectasia mutated (ATM) signaling is activated independent of DNA double strand breaks (DSBs) in CAFs derived from human breast cancers compared with paired normal fibroblasts (NFs). Recent studies have shown that ATM protein kinase, as a redox sensor, is closely associated with cellular energy metabolism. Thus, it is very possible that ATM protein kinase regulates the EMR of CAFs. So, it is necessary to perform an integral study on how oxidized ATM regulates the EMR of CAFs in response to various stimuli evoking OS. This will facilitate to develop a new powerful strategy of preventing and treating cancers.

Intersectin-1s: an important regulator of cellular and molecular pathways in lung injury

Abstract Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe syndromes resulting from the diffuse damage of the pulmonary parenchyma. ALI and ARDS are induced by a plethora of local or systemic insults, leading to the activation of multiple pathways responsible for injury, resolution, and repair or scarring of the lungs. Despite the large efforts aimed at exploring the roles of different pathways in humans and animal models and the great strides made in understanding the pathogenesis of ALI/ARDS, the only viable treatment options are still dependent on ventilator and cardiovascular support. Investigation of the pathophysiological mechanisms responsible for initiation and resolution or advancement toward lung scarring in ALI/ARDS animal models led to a better understanding of the disease's complexity and helped in elucidating the links between ALI and systemic multiorgan failure. Although animal models of ALI/ARDS have pointed out a variety of new ideas for study, there are still limited data regarding the initiating factors, the critical steps in the progression of the disease, and the central mechanisms dictating its resolution or progression to lung scarring. Recent studies link deficiency of intersectin-1s (ITSN-1s), a prosurvival protein of lung endothelial cells, to endothelial barrier dysfunction and pulmonary edema as well as to the repair/recovery from ALI. This review discusses the effects of ITSN-1s deficiency on pulmonary endothelium and its significance in the pathology of ALI/ARDS.

The Rac1 hypervariable region in targeting and signaling: a tail of many stories

Cellular signaling by small GTPases is critically dependent on proper spatio-temporal orchestration of activation and output. In addition to their core G (guanine nucleotide binding)-domain, small GTPases comprise a hypervariable region (HVR) and a lipid anchor that are generally accepted to control subcellullar localization. The HVR encodes in many small GTPases a polybasic region (PBR) that permits charge-mediated association to the inner leaflet of the plasma membrane or to intracellular organelles. Over the past 15-20 years, evidence has accumulated for specific protein-protein interactions, mediated by the HVR, that control both targeting and signaling specificity of small GTPases. Using the RhoGTPase Rac1 as a paradigm we here review a series of protein partners that require the Rac1 HVR for association and that control various aspects of localized Rac1 signaling. Some of these proteins represent Rac1 activators, whereas others mediate Rac1 inactivation and degradation and yet others potentiate Rac1 downstream signaling. Finally, evidence is discussed which shows that the HVR of Rac1 also contributes to effector interactions, co-operating with the N-terminal effector domain. The complexity of localized Rac1 signaling, reviewed here, is most likely exemplary for many other small GTPases as well, representing a challenge to identify and define similar mechanisms controlling the specific signaling induced by small GTPases.