Search

Table S1-siRNA sequences used in this study

AMBRA1 promotes TGF-β signaling dependent of its ubiquitin ligase activity.

Transforming growth factor β (TGFβ) is prometastatic in advanced cancers and its biological activities are mainly mediated by the Smad family of proteins. Smad4 is the central signal transducer and transcription factor in the TGFβ pathway, yet the underlying mechanisms that govern transcriptional activities of Smad4 are not fully understood. Here, we show that AMBRA1, a member of the DDB1 and CUL4-associated factor (DCAF) family of proteins, serves as the substrate receptor for Smad4 in the CUL4-RING (CRL4) ubiquitin ligase complex. The CRL4-AMBRA1 ubiquitin ligase mediates nonproteolytic polyubiquitylation of Smad4 to enhance its transcriptional functions. Consequently, AMBRA1 potentiated TGFβ signaling and critically promoted TGFβ-induced epithelial-to-mesenchymal transition, migration, and invasion of breast cancer cells. Mouse models of breast cancer demonstrated that AMBRA1 promotes metastasis. Collectively, these results show that CRL4-AMBRA1 facilitates TGFβ-driven metastasis by increasing Smad4 polyubiquitylation, suggesting AMBRA1 may serve as a new therapeutic target in metastatic breast cancer.Significance:This study identifies AMBRA1 as a novel regulator of TGFβ signaling and breast cancer metastasis, supporting further exploration of AMBRA1 as a target for cancer therapy.

Background Extensive cervicofacial reconstruction is challenging for plastic surgeons. Because of the location of the adjacent scalp flap nourished by the superficial temporal artery (STA), it can be a candidate for cervicofacial reconstruction. Objectives This article aims to report a combined treatment of an expanded island STA flap and an 810-nm diode laser hair removal technique for extensive cervicofacial defects. Methods Between January 2015 and December 2018, 10 patients with lower face and neck scar contraction were reconstructed with a bilateral or unilateral expanded STA island flap and an 810-nm diode laser for hair removal in this retrospective study. Hair removal via the 810-nm laser was started when the injected volume reached the volume of the expander, with a fluence of 35 to 40 J/cm2 and a 1 to 2 Hz repetition rate. Before second-stage surgery, the hair reduction rate was assessed. Twelve months after surgery, the degree of epilation efficacy according to the satisfaction scale and Global Aesthetic Improvement Scale was evaluated. Results This study included 2 single-pedicle flaps and 8 double-pedicle flaps. The average size of the implanted expanders was 600 mL. The average injected volume was 1405 mL. Before second surgery, there was a 67.4% hair reduction rate. Twelve months after surgery, the results of Global Aesthetic Improvement Scale were very good (3), good (6), average (1), and poor (0). Conclusions The expanded island STA flap and 810-nm diode laser technique may be a novel treatment option for severe face and neck aesthetic reconstruction.

Background Keloid is a dermal fibroproliferative disease with various etiologies and unclear pathogenesis. Recent studies have revealed that circular RNAs (circRNAs) exerted regulatory functions through a competing endogenous RNA (ceRNA) pathway in keloid progression. However, the expression profiles of circRNAs in keloid dermal tissues (KDTs) remain unknown. This study aimed to identify differentially expressed circRNAs (DECs) and genes (DEGs) in KDTs, as well as to investigate the potential biological functionsof circRNAs based on the circRNA-miRNA-mRNA ceRNA network. Results Through high-throughput RNA sequencing (RNA-seq), we revealed 3467 DEGs (865 up- and 2602 down-regulated) and 330 DECs (162 up- and 168 down-regulated) in KDTs. To reveal the functions of DECs preliminarily, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed for the host genes. Further, the up- and down-regulated DECs-miRNAs-DEGs regulatory networks were constructed, respectively. The functional prediction for the target genes showed that the up-regulated ceRNA network was associated with extracellular matrix and multiple cellular functions. The down-regulated ceRNA network was enriched in cell-cell junction and other biological processes. Cytoscape was used to visualize each network's protein-protein interaction (PPI) network and identify hub genes. By quantitative Real-Time PCR (qRT-PCR), hsa_circ_0060927, hsa_circ_0071410, hsa_circ_0058092, hsa_circ_0002874, hsa_circ_0004682, hsa_circ_0072688, hsa_circ_0006401, and hsa_circ_0055954 were identified significantly up-regulated in KDTs. Within, hsa_circ_0072688, which was up-regulated both in KDTs and keloid dermal fibroblasts (KDFs), and located in the cytoplasm, might be a key circRNA and affect the progression of keloid by impacting extracellular matrix, cell adhesion, and cell apoptosis, etc. Conclusion This study not only filled a gap in the circRNA library of KDTs but also laid a foundation for probing the biological function of DECs in keloids. Hsa_circ_0072688 was thought to be a key circRNA and more experimental support is needed.

Transforming growth factor β (TGFβ) is prometastatic in advanced cancers and its biological activities are mainly mediated by the Smad family of proteins. Smad4 is the central signal transducer and transcription factor in the TGFβ pathway, yet the underlying mechanisms that govern transcriptional activities of Smad4 are not fully understood. Here, we show that AMBRA1, a member of the DDB1 and CUL4-associated factor (DCAF) family of proteins, serves as the substrate receptor for Smad4 in the CUL4-RING (CRL4) ubiquitin ligase complex. The CRL4-AMBRA1 ubiquitin ligase mediates nonproteolytic polyubiquitylation of Smad4 to enhance its transcriptional functions. Consequently, AMBRA1 potentiated TGFβ signaling and critically promoted TGFβ-induced epithelial-to-mesenchymal transition, migration, and invasion of breast cancer cells. Mouse models of breast cancer demonstrated that AMBRA1 promotes metastasis. Collectively, these results show that CRL4-AMBRA1 facilitates TGFβ-driven metastasis by increasing Smad4 polyubiquitylation, suggesting AMBRA1 may serve as a new therapeutic target in metastatic breast cancer. Significance: This study identifies AMBRA1 as a novel regulator of TGFβ signaling and breast cancer metastasis, supporting further exploration of AMBRA1 as a target for cancer therapy.

BACKGROUND Vascular supercharge and flap prefabrication are two surgical maneuvers to improve flap blood supply. Although these techniques have been studied intensively, few studies have focused on the differences between supercharge and prefabricated flaps regarding their flap survival areas, vasculatures, and hemodynamics. METHODS In this study, 21 male Sprague-Dawley rats were divided into three groups as follows: group A, single perforator flap; group B, supercharge flap; and group C, prefabricated flap. Flap survival was measured 1 week after flap elevation. Indocyanine green angiography was applied to visualize flap vascularity and to analyze flap hemodynamics. Von Willebrand factor immunohistochemical staining was applied to assess the number of microvessels in the choke zone of the abdominal wall. RESULTS The flap survival areas were expanded significantly in the arteriovenous supercharge group and the vascular bundle prefabricated group compared with that in the single-perforator group (81.34 ± 8.12 percent and 75.51 ± 8.08 percent versus 46.27 ± 10.01 percent, respectively; p < 0.05). Hemodynamic analysis suggested that although a significant increase in arterial infusion could be achieved with flap prefabrication, the venous effusion of the prefabricated flap was the worst among the three groups, indicating greater susceptibility to compromised venous return. Active neovascularization was confirmed by an increased number of microvessels in group C. Specifically, the dilatation of choke vessels and the newly formed vessels of the prefabricated pedicle could be appreciated by indocyanine green angiographic mapping. CONCLUSIONS Both vascular supercharge and flap prefabrication can augment the blood supply of the perforator flap but by means of different mechanisms. Because a supercharge flap is less susceptible to venous compromise, it is suggested to first consider the use of vascular supercharging when feasible.

Background Manitoba-oculo-tricho-anal (MOTA) syndrome is a rare syndrome with only 27 cases reported worldwide so far, but none was reported in the population of Eastern Asia. Such extremely low prevalence might be contributed by misdiagnosis due to its similarities in ocular manifestations with facial cleft. In our study, we discovered the first case of MOTA syndrome in the population of China, with 2 novel FRAS1 related extracellular matrix 1 (FREM1) gene stop-gain mutations confirmed by whole exome sequencing. Case presentation A 12-year-old Chinese girl presented with facial cleft-like deformities including aberrant hairline, blepharon-coloboma and broad bifid nose since birth. Whole exome sequencing resulted in the identification of 2 novel stop-gain mutations in the FREM1 gene. Diagnosis of MOTA syndrome was then established. Conclusions We discovered the first sporadic case of MOTA syndrome according to clinical manifestations and genetic etiology in the Chinese population. We have identified 2 novel stop-gain mutations in FREM1 gene which further expands the spectrum of mutational seen in the MOTA syndrome. Further research should be conducted for better understanding of its mechanism, establishment of an accurate diagnosis, and eventually the exploitation of a more effective and comprehensive therapeutic intervention for MOTA syndrome.

Importance: The strategic option between vascular supercharge and flap prefabrication in the fabrication of multipedicle flaps for difficult head and neck reconstruction has not been reported. Obje...

Aged skin wounds heal poorly, resulting in medical, economic, and social burdens posed by nonhealing wounds. Age-related defects in repair are associated with reduced myofibroblasts and dysfunctional extracellular matrix (ECM) deposition. Bidirectional cell-cell communication involving exosome-borne cargo such as micro RNAs (miRs) has emerged as a critical mechanism for wound healing and aged tissue regeneration. Here we report that at the wound edge, aged fibroblasts display reduced migration and differentiation into myofibroblasts, with impaired ECM deposition, when compared with young tissue. Proper activation of fibroblasts to myofibroblasts may alleviate age-related defects in wound healing. Herein, an exosome-guided cell technique was performed to induce effective wound healing. Supplementing wounds with exosomes isolated from young mouse wound-edge fibroblasts (exosomesYoung) significantly improved the abundance of myofibroblasts and wound healing in aged mice and caused fibroblasts to migrate and transition to myofibroblasts in vitro. To determine the underlying mechanism, we found that exosomal transfer of miR-125b to fibroblasts inhibited sirtuin 7 (Sirt7), thus accelerating myofibroblast differentiation and wound healing in aged mice. Notably, after epidermal inhibition of miR-125b or overexpression of Sirt7 in fibroblasts, migration and myofibroblast transition were perturbed. Our findings thus reveal that miR-125b is transferred through exosomes from young fibroblasts to old fibroblasts contributes to promoting fibroblast migration and transition to counteract aging, suggesting a potential avenue for anti-aging interventions in wound healing. Graphical Abstract

Objective To investigate the utility of pre-expanded muscle-sparing latissimus dorsi flaps in the reconstruction of deformities secondary to severe scar contractures on the anterior chest. Methods The function of the latissimus dorsi was preserved with blood supply from the main or lateral branch of the thoracodorsal artery. The entire treatment period was divided into two stages, during which segmental latissimus dorsi flaps were pre-expanded in stage I and anterior chest scar deformities were reconstructed in stage II. During stage I, the musculocutaneous perforators arising from the lateral branch of the thoracodorsal artery were determined by ultrasound preoperatively; the flap design included the anterior segment of the latissimus dorsi supplied by the musculocutaneous perforators from the lateral branch; and a tissue expander was placed following flap dissection and then infused with saline intermittently for 4–6 months. In stage II, the chest scars were excised, and breast tissues were repositioned; the continuity of the medial branch of the thoracodorsal nerve to the muscle was preserved when reconstruction was performed using the segmental latissimus dorsi flaps supplied by the main or lateral branch of the thoracodorsal artery. Results From October 2010 to October 2019, 21 patients (on 24 sides) underwent reconstructive procedures for extensive scar contractures on the anterior chest. All flaps survived, and their donor sites were sutured directly. During a follow-up of 3 months to 8 years, the flaps became soft and exhibited color similar to that of the adjacent tissues. The limited neck and shoulder movements improved, and postoperatively, all female patients were satisfied with the shape of their breasts. Additionally, neither apparent weakening on the adduction, internal rotation, or extension strength of the shoulder joint on the affected side nor marked depression deformity in the back was observed. Conclusion Pre-expanded muscle-sparing latissimus dorsi flaps with blood supply from the main or lateral branch of the thoracodorsal artery proved to be a desirable option for the reconstruction of extensive scar contractures on the anterior chest.

AbstractThe immune system plays an essential role in the development of tumors, which has been demonstrated in multiple types of cancers. Consistent with this, immunotherapies with targets that disrupt these mechanisms and turn the immune system against developing cancers have been proven effective. In neurofibromatosis type 1 (NF1), an autosomal dominant genetic disorder, the understanding of the complex interactions of the immune system is incomplete despite the discovery of the pivotal role of immune cells in the tumor microenvironment. Individuals with NF1 show a loss of the NF1 gene in nonneoplastic cells, including immune cells, and the aberrant immune system exhibits intriguing interactions with NF1. This review aims to provide an update on recent studies showing the bilateral influences of NF1 mutations on immune cells and how the abnormal immune system promotes the development of NF1 and NF1-related tumors. We then discuss the immune receptors major histocompatibility complex class I and II and the PD-L1 mechanism that shield NF1 from immunosurveillance and enable the immune escape of tumor tissues. Clarification of the latest understanding of the mechanisms underlying the effects of the abnormal immune system on promoting the development of NF1 will indicate potential future directions for further studies and new immunotherapies.

Background Hypertrophic scar (HTS) is a fibrotic disorder of skins and may have repercussions on the appearance as well as functions of patients. Recent studies related have shown that competitive endogenous RNA (ceRNA) networks centering around miRNAs may play an influential role in HTS formation. This study aimed to construct and validate a three-miRNA (miR-422a, miR-2116-3p, and miR-3187-3p) ceRNA network, and explore its potential functions. Methods Quantitative real‑time PCR (qRT‑PCR) was used to compare expression levels of miRNAs, lncRNAs, and genes between HTS and normal skin. Target lncRNAs and genes of each miRNA were predicted using starBase as well as TargetScan database to construct a distinct ceRNA network; overlapping target lncRNAs and genes of the three miRNAs were utilized to develop a three-miRNA ceRNA network. For every network, protein–protein interaction (PPI) network analysis was performed to identify its hub genes. For each network and its hub genes, Gene Oncology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were conducted to explore their possible functions. Results MiR-422a, miR-2116-3p, and miR-3187-3p were all downregulated in HTS tissues and fibroblasts. MiR-422a-based ceRNA network consisted of 101 lncRNAs with 133 genes; miR-2116-3p-centered ceRNA network comprised 85 lncRNAs and 978 genes; miR-3187-3p-derived ceRNA network encompassed 84 lncRNAs as well as 1128 genes. The three-miRNA ceRNA network included 2 lncRNAs with 9 genes, where MAPK1, FOSL2, ABI2, KPNA6, CBL, lncRNA-KCNQ1OT1, and lncRNA-EBLN3P were upregulated. According to GO and KEGG analysis, these networks were consistently related to ubiquitination. Three ubiquitination-related genes (CBL, SMURF2, and USP4) were upregulated and negatively correlated with the expression levels of the three miRNAs in HTS tissues. Conclusions This study identified a three-miRNA ceRNA network, which might take part in HTS formation and correlate with ubiquitination.

Description, HSPA13 is a novel checkpoint regulator in the TNFα signaling pathway controlling cellular physiological outcomes., RIP1 has emerged as a master regulator in TNFα signaling that controls two distinct cellular fates: cell survival versus programmed cell death. Because the default response of most cells to TNFα is NF-κB–mediated inflammation and survival, a specific mechanism must exist to control the divergence of signaling outcome. Here, we identify HSPA13 as a transcription-independent checkpoint to modulate the role of RIP1 in TNFα signaling. Through specific binding to TNFR1 and RIP1, HSPA13 enhances TNFα-induced recruitment of RIP1 to TNFR1, and consequently promotes downstream NF-κB transcriptional responses. Meanwhile, HSPA13 attenuates the participation of RIP1 in cytosolic complex II and prevents cells from programmed death. Loss of HSPA13 shifts the transition of RIP1 from complex I to complex II and promotes both apoptosis and necroptosis. Thus, our study provides compelling evidence for the cellular protective function of HSPA13 in fine-tuning TNFα responses.

Background Hypertrophic scar (HTS) is a fibroproliferative skin disorder characterized by excessive cell proliferation, migration, and extracellular matrix (ECM) deposition. The CUB and Sushi multiple domains 1 (CSMD1) has previously been identified as the key regulatory gene of hypertrophic scar by a large sample GWAS study. However, further research has not yet been conducted to verify this finding in other HTS patients and to determine the underlying mechanism. Results In this study, we verified that CSMD1 was downregulated in both HTS tissue and HTS-derived fibroblasts. The knockdown of CSMD1 resulted in enhanced migration and fibronectin1 (FN1) secretion in fibroblasts in vitro. In addition, the upstream and downstream regulatory mechanisms of CSMD1 were also investigated through microRNA (miRNA) databases screening and RNA-sequencing (RNA-seq) respectively. The screening of four common microRNA (miRNA) databases suggested that miR-190a-3p binds to the CSMD1 and may regulate its expression. We confirmed that miR-190a-3p directly targeted the CSMD1–3′-UTR using luciferase reporter assays. Furthermore, the overexpression of miR-190a-3p showed promotion of migratory activity and FN1 secretion in fibroblasts, resembling the effect of CSMD1 knockdown; whereas the knockdown of miR-190a-3p exerted the opposite effect. Finally, transcriptomic analysis showed activation of Janus kinase-signal transducer and activator of transcription (JAK/STAT) signaling pathway in the CSMD1 knockdown fibroblasts. Conclusions This study has validated the conclusions of the previous GWAS study conducted in Chinese population. In vitro experiments have provided further evidence on the function of CSMD1 in the development of HTS, and have also revealed the underlying upstream and downstream regulating mechanisms. Additionally, the JAK/STAT signaling pathway identified using RNA-seq might provide a potential treatment approach, especially for HTS.

Fibroblasts are the chief effector cells in fibrotic diseases and have been discovered to be highly heterogeneous. Recently, fibroblast heterogeneity in human skin has been studied extensively and several surface markers for dermal fibroblast subtypes have been identified, holding promise for future antifibrotic therapies. However, it has yet to be confirmed whether surface markers should be looked upon as merely lineage landmarks or as functional entities of fibroblast subtypes, which may further complicate the interpretation of cellular function of these fibroblast subtypes. This review aims to provide an update on current evidence on fibroblast surface markers in fibrotic disorders of skin as well as of other organ systems. Specifically, studies where surface markers were treated as lineage markers and manipulated as functional membrane proteins are both evaluated in parallel, hoping to reveal the underlying mechanism behind the pathogenesis of tissue fibrosis contributed by various fibroblast subtypes from multiple angles, shedding lights on future translational researches.

Loss of TGF-β tumour suppressive response is a hallmark of human cancers. As a central player in TGF-β signal transduction, SMAD4 (also known as DPC4) is frequently mutated or deleted in gastrointestinal and pancreatic cancer. However, such genetic alterations are rare in most cancer types and the underlying mechanism for TGF-β resistance is not understood. Here we describe a mechanism of TGF-β resistance in ALK-positive tumours, including lymphoma, lung cancer and neuroblastoma. We demonstrate that, in ALK-positive tumours, ALK directly phosphorylates SMAD4 at Tyr 95. Phosphorylated SMAD4 is unable to bind to DNA and fails to elicit TGF-β gene responses and tumour suppressing responses. Chemical or genetic interference of the oncogenic ALK restores TGF-β responses in ALK-positive tumour cells. These findings reveal that SMAD4 is tyrosine-phosphorylated by an oncogenic tyrosine kinase during tumorigenesis. This suggests a mechanism by which SMAD4 is inactivated in cancers and provides guidance for targeted therapies in ALK-positive cancers. Zhang et al. show that ALK phosphorylates SMAD4 at Tyr 95 to block its binding to DNA, representing a mutation-independent mechanism for blocking the tumour suppressor function of TGF-β in ALK-positive cancers.

Fibroblasts (Fbs) are critical to hypertrophic scar (HTS) formation and were recently shown to be highly heterogeneous. However, Fb heterogeneity in HTSs has not been fully elucidated. In this study, we observed an increased fraction of CD39+ Fbs in HTS after screening four Fb subtypes (CD26+, CD36+, FAP+, and CD39+). CD39+ Fbs, enriched in the upper dermis, were positively correlated with scar severity. The transcriptional analysis of CD39+ and CD39– Fbs sorted from HTS revealed that IL-11 was more highly expressed in CD39+ Fbs. We then showed that IL-11 was upregulated in HTSs and that its expression was induced by TGFβ1 in vitro. TGFβ1 also stimulated the expression of CD39 at the transcriptional and protein levels, mediating the maintenance of the CD39+ phenotype. Furthermore, IL-11 facilitated myofibroblast activation and extracellular matrix production in both CD39+ and CD39– Fbs. Interestingly, CD39+ Fbs secreted more IL-11 on TGFβ1 treatment and were less responsive to IL-11 than CD39– Fbs. Notably, a CD39 inhibitor effectively reduced stretch-induced scar formation and attenuated bleomycin-induced skin fibrosis, suggesting an antiscarring approach by targeting CD39+ Fbs.

Smads are critical intracellular signal transducers for transforming growth factor-β (TGF-β) in mammalian cells. In this study, we have identified WD repeat-containing protein 74 (WDR74) as a novel transcriptional coactivator for Smads in the canonical TGF-β signaling pathway. Through direct interactions with Smad proteins, WDR74 enhances TGF-β-mediated phosphorylation and nuclear accumulation of Smad2 and Smad3. Consequently, WDR74 enables stronger transcriptional responses and more robust TGF-β-induced physiological responses. Our findings have elucidated a critical role of WDR74 in regulating TGF-β signaling.

Fibroblasts (Fbs) are critical to hypertrophic scar (HTS) formation and were recently shown to be highly heterogeneous. However, Fb heterogeneity in HTSs has not been fully elucidated. In this study, we observed an increased fraction of CD39

With advances in anatomical knowledge and technology, increased interest has been directed towards reconstruction with enhanced aesthetic and functional outcomes. A myriad of thinned perforator flap harvest approaches have been developed for this purpose; however, concerns about jeopardizing their vascularity remain. To ensure optimum reconstructive outcome without hampering the flap’s microcirculation, it is important to make good use of the existing advanced imaging modalities that can provide clear visualization of perforator branches, particularly in the adipose layer, and an accurate assessment of flap perfusion. Therefore, this review will highlight the imaging modalities that have been utilized for harvesting a thinned perforator flap from these two perspectives, along with future insights into creating both functionally and aesthetically satisfying, yet simultaneously safe, thinned perforator flaps for the best reconstructive outcomes for patients.

Background Microsurgical replantation has become the most favorable treatment option for scalp avulsion. However, the accurate prediction of postoperative replant viability remains challenging. Case presentation In this article, we showed that (indocyanine green angiography, ICGA) can provide a much more precise prediction of replant necrosis than conventional clinical assessment in a rare case of complete scalp avulsion with prolonged ischemia time. Conclusion Clinical assessment of replant survival may be misleading in cases of complex tissue injuries and prolonged ischemic stress. This case provides insight into the promising utility of ICGA as an important adjuvant tool to better assess tissue perfusion and viability in scalp avulsion and possibly other types of replantation.

Smad7 is a negative feedback product of TGF-β superfamily signaling and fine tunes a plethora of pleiotropic responses induced by TGF-β ligands. However, its noncanonical functions independent of TGF-β signaling remain to be elucidated. Here, we show that Smad7 activates signal transducers and activators of transcription 3 (STAT3) signaling in maintaining mouse embryonic stem cell pluripotency in a manner independent of the TGF-β receptors, yet dependent on the leukemia inhibitory factor (LIF) coreceptor glycoprotein 130 (gp130). Smad7 directly binds to the intracellular domain of gp130 and disrupts the SHP2-gp130 or SOCS3-gp130 complex, thereby amplifying STAT3 activation. Consequently, Smad7 facilitates LIF-mediated self-renewal of mouse ESCs and is also critical for induced pluripotent stem cell reprogramming. This finding illustrates an uncovered role of the Smad7-STAT3 interplay in maintaining cell pluripotency and also implicates a mechanism involving Smad7 underlying cytokine-dependent regulation of cancer and inflammation.

Numerous studies have shown that macrophages can orchestrate the microenvironment from the early stage of wound healing to the later stages of scar formation. However, few reviews have highlighted the significance of macrophages during the formation of abnormal scars. The purpose of this review was to outline the polarization of macrophages from early to late stage of pathological scar formation, focusing on spatiotemporal diversity of M1 and M2 macrophages. In this review, the role of macrophages in the formation of hypertrophic scars and keloids is summarized in detail. First, an increased number of M2 cells observed before injuries are significantly associated with susceptibility to abnormal scar pathogenesis. Second, decreased expression of M1 at the early stage and delayed expression of M2 at the late stage results in pathological scar formation. Third, M2 cells are highly expressed at both the margin and the superficial region, which is consistent with the invasive property of keloids. Finally, this review helps to characterize strategies for the prediction and prevention of pathological scar formation.

The epithelial-to-mesenchymal transition (EMT) is a process by which differentiated epithelial cells reprogram gene expression, lose their junctions and polarity, reorganize their cytoskeleton, increase cell motility and assume a mesenchymal morphology. Despite the critical functions of the microtubule (MT) in cytoskeletal organization, how it participates in EMT induction and maintenance remains poorly understood. Here we report that acetylated α-tubulin, which plays an important role in microtubule (MT) stabilization and cell morphology, can serve as a novel regulator and marker of EMT. A high level of acetylated α-tubulin was correlated with epithelial morphology and it profoundly decreased during TGF-β-induced EMT. We found that TGF-β increased the activity of HDAC6, a major deacetylase of α-tubulin, without affecting its expression levels. Treatment with HDAC6 inhibitor tubacin or TGF-β type I receptor inhibitor SB431542 restored the level of acetylated α-tubulin and consequently blocked EMT. Our results demonstrate that acetylated α-tubulin can serve as a marker of EMT and that HDAC6 represents an important regulator during EMT process.

Loss of TGF-β tumour suppressive response is a hallmark of human cancers. As a central player in TGF-β signal transduction, SMAD4 (also known as DPC4) is frequently mutated or deleted in gastrointestinal and pancreatic cancer. However, such genetic alterations are rare in most cancer types and the underlying mechanism for TGF-β resistance is not understood. Here we describe a mechanism of TGF-β resistance in ALK-positive tumours, including lymphoma, lung cancer and neuroblastoma. We demonstrate that, in ALK-positive tumours, ALK directly phosphorylates SMAD4 at Tyr 95. Phosphorylated SMAD4 is unable to bind to DNA and fails to elicit TGF-β gene responses and tumour suppressing responses. Chemical or genetic interference of the oncogenic ALK restores TGF-β responses in ALK-positive tumour cells. These findings reveal that SMAD4 is tyrosine-phosphorylated by an oncogenic tyrosine kinase during tumorigenesis. This suggests a mechanism by which SMAD4 is inactivated in cancers and provides guidance for targeted therapies in ALK-positive cancers.