Protein expression of the amino acid transporter SLC7A5 in tumor tissue is prognostic in early-stage colorectal cancer.

Proteins overexpressed in early-stage cancers may serve as early diagnosis and prognosis markers as well as targets for cancer therapies. In this study, we examined the expression of an essential amino acid carrier SLC7A5 (LAT1, CD98, or 4F2 light chain) in cancer tissue from two well-annotated cohorts of 575 cases of early-stage and 106 cases of late-stage colorectal cancer patients. Immunohistochemistry showed SLC7A5 overexpression in 72.0% of early-stage and 56.6% of late-stage cases. SLC7A5 expression was not influenced by patient gender, age, location, or mismatch repair status, although it appeared to be slightly less prevalent in tumors of mucinous differentiation or with lymphovascular invasion. Statistical analyses revealed a positive correlation between SLC7A5 overexpression and both overall survival and disease-free survival in early-stage but not late-stage cancers. Co-expression analyses of the TCGA and CPTAC colorectal cancer cohorts identified a network of gene transcripts positively related to SLC7A5, with its heterodimer partner SLC3A2 having the highest co-expression score. Network analysis uncovered the SLC7A network to be significantly associated with ncRNA such as tRNA processing and the mitotic cell cycle. Since SLC7A5 is also a marker of activated lymphocytes such as NK, T, and B lymphocytes, SLC7A5 overexpression in early colorectal cancers might trigger a strong anti-tumor immune response which could results in better clinical outcome. Overall, our study provides clear evidence of differential SLC7A5 expression and its prognostic value for early-stage colorectal cancer, although the understanding of its functions in colorectal tumorigenesis and cancer immunity is currently rather limited and awaits further characterization.

Adrenergic microenvironment driven by cancer-associated Schwann cells contributes to chemoresistance in patients with lung cancer.

Doublecortin (DCX)-positive neural progenitor-like cells are purported components of the cancer microenvironment. The number of DCX-positive cells in tissues reportedly correlates with cancer progression; however, little is known about the mechanism by which these cells affect cancer progression. Here we demonstrated that DCX-positive cells, which are found in all major histological subtypes of lung cancer, are cancer-associated Schwann cells (CAS) and contribute to the chemoresistance of lung cancer cells by establishing an adrenergic microenvironment. Mechanistically, the activation of the Hippo transducer YAP/TAZ was involved in the acquisition of new traits of CAS and DCX positivity. We further revealed that CAS express catecholamine-synthesizing enzymes and synthesize adrenaline, which potentiates the chemoresistance of lung cancer cells through the activation of YAP/TAZ. Our findings shed light on CAS, which drive the formation of an adrenergic microenvironment by the reciprocal regulation of YAP/TAZ in lung cancer tissues.

Role of catecholamine synthases in the maintenance of cancer stem-like cells in malignant peripheral nerve sheath tumors.

Malignant peripheral nerve sheath tumors (MPNSTs) are malignant tumors that are derived from Schwann cell lineage around peripheral nerves. As in many other cancer types, cancer stem cells (CSCs) have been identified in MPNSTs, and they are considered the cause of treatment resistance, recurrence, and metastasis. As an element defining the cancer stemness of MPNSTs, we previously reported a molecular mechanism by which exogenous adrenaline activates a core cancer stemness factor, YAP/TAZ, through ß2 adrenoceptor (ADRB2). In this study, we found that MPNST cells express catecholamine synthases and that these enzymes are essential for maintaining cancer stemness, such as the ability to self-renew and maintain an undifferentiated state. Through gene knockdown and inhibition of these enzymes, we confirmed that catecholamines are indeed synthesized in MPNST cells. The results confirmed that catecholamine synthase knockdown in MPNST cells reduces the activity of YAP/TAZ. These data suggest that a mechanism of YAP/TAZ activation by de novo synthesized adrenaline, as well as exogenous adrenaline, may exist in the maintenance of cancer stemness of MPNST cells. This mechanism not only helps to understand the pathology of MPNST, but could also contribute to the development of therapeutic strategies for MPNST.

Connective tissue mast cells store and release noradrenaline.

Mast cells are present in mucosal and connective tissues throughout the body. They synthesize and release a wide variety of bioactive molecules, such as histamine, proteases, and cytokines. In this study, we found that a population of connective tissue mast cells (CTMCs) stores and releases noradrenaline, originating from sympathetic nerves. Noradrenaline-storing cells, not neuronal fibers, were predominantly identified in the connective tissues of the skin, mammary gland, gastrointestinal tract, bronchus, thymus, and pancreas in wild-type mice but were absent in mast cell-deficient W-sash c-kit mutant KitW-sh/W-sh mice. In vitro studies using bone marrow-derived mast cells revealed that extracellular noradrenaline was taken up but not synthesized. Upon ionomycin stimulation, noradrenaline was released. Electron microscopy analyses further suggested that noradrenaline is stored in and released from the secretory granules of mast cells. Finally, we found that noradrenaline-storing CTMCs express organic cation transporter 3 (Oct3), which is also known as an extraneuronal monoamine transporter, SLC22A3. Our findings indicate that mast cells may play a role in regulating noradrenaline concentration by storing and releasing it in somatic tissues.

A novel carotenoid biosynthetic route via oxidosqualene.

Over 800 known carotenoids are synthesized from phytoene or 4,4'-diapophytoene (dehydrosqualene) characterized by three conjugated double bonds. In this paper, we report that carotenoid desaturase CrtN from Staphylococcus aureus and Methylomonas can accept oxidosqualene, which is the precursor for plant- or animal-type triterpenoids, yielding the yellow carotenoid pigments with 8, 9, or 10 conjugated double bonds. The resulting pathway is the second nonnatural route for carotenoid pigments and the first pathway for carotenoid pigments not biosynthesized via (diapo)phytoene.

YES1 as a Therapeutic Target for HER2-Positive Breast Cancer after Trastuzumab and Trastuzumab-Emtansine (T-DM1) Resistance Development.

Trastuzumab-emtansine (T-DM1) is a therapeutic agent molecularly targeting human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC), and it is especially effective for MBC with resistance to trastuzumab. Although several reports have described T-DM1 resistance, few have examined the mechanism underlying T-DM1 resistance after the development of acquired resistance to trastuzumab. We previously reported that YES1, a member of the Src family, plays an important role in acquired resistance to trastuzumab in HER2-amplified breast cancer cells. We newly established a trastuzumab/T-DM1-dual-resistant cell line and analyzed the resistance mechanisms in this cell line. At first, the T-DM1 effectively inhibited the YES1-amplified trastuzumab-resistant cell line, but resistance to T-DM1 gradually developed. YES1 amplification was further enhanced after acquired resistance to T-DM1 became apparent, and the knockdown of the YES1 or the administration of the Src inhibitor dasatinib restored sensitivity to T-DM1. Our results indicate that YES1 is also strongly associated with T-DM1 resistance after the development of acquired resistance to trastuzumab, and the continuous inhibition of YES1 is important for overcoming resistance to T-DM1.

Construction of a pathway to C50-ε-carotene.

Substrate tolerance of bacterial cyclases has been demonstrated in various contexts, but little is known about that of plant cyclases. Here, we tested two plant ε-cyclases to convert C50-lycopene, which we previously established by rounds of directed evolution. Unlike bacterial ß-cyclases, two-end cyclase from lettuce exhibited complete specificity against this molecule, indicating that this enzyme has some mechanism that exerts size-specificity. Arabidopsis one-end cyclase At-y2 showed detectable activity to C50-lycopene. Interestingly, we found that it functions as a two-end cyclase in a C50 context. Based on this observation, a possible model for substrate discrimination of this enzyme is proposed.

Nonnatural biosynthetic pathway for 2-hydroxylated xanthophylls with C50-carotenoid backbone.

Carotenoids are structurally diverse pigments with various important biological functions. There has been a large interest in the search for novel carotenoid structures, since only a slight structural changes can result in a drastic difference in their biological functions. Carotenoid-modifying enzymes show remarkable substrate promiscuity, allowing rapid access to a vast set of novel carotenoids by combinatorial biosynthesis. We previously constructed a nonnatural carotenoid biosynthetic pathway in Escherichia coli that can produce C50 carotenoids having a longer chain than their natural C40 counterparts. In this study, a carotenoid 2,2'-hydroxylase (crtG) from Brevundimonas sp. SD212 was coexpressed together with our laboratory-engineered C50-zeaxanthin and C50-astaxanthin biosynthetic pathways. We identified six novel nonnatural C50-xanthophylls, namely, C50-nostoxanthin, C50-caloxanthin, C50-adonixanthin, C50-4-ketonostoxanthin, C50-2-hydroxyastaxanthin, and C50-2,2'-dihydroxyastaxanthin.

Construction of a Nonnatural C60 Carotenoid Biosynthetic Pathway.

Longer-chain carotenoids have interesting physiological and electronic/photonic properties due to their extensive polyene structures. Establishing nonnatural biosynthetic pathways for longer-chain carotenoids in engineerable microorganisms will provide a platform to diversify and explore the potential of these molecules. We have previously reported the biosynthesis of nonnatural C50 carotenoids by engineering a C30-carotenoid backbone synthase (CrtM) from Staphylococcus aureus. In the present work, we conducted a series of experiments to engineer C60 carotenoid pathways. Stepwise introduction of cavity-expanding mutations together with stabilizing mutations progressively shifted the product size specificity of CrtM toward efficient synthases for C60 carotenoids. By coexpressing these CrtM variants with hexaprenyl diphosphate synthase, we observed that C60-phytoene accumulated together with a small amount of C65-phytoene, which is the largest carotenoid biosynthesized to date. Although these carotenoids failed to serve as a substrate for carotene desaturases, the C25-half of the C55-phytoene was accepted by the variant of phytoene desaturase CrtI, leading to accumulation of the largest carotenoid-based pigments. Continuing effort should further expand the scope of carotenoids, which are promising components for various biological (light-harvesting, antioxidant, and communicating) and nonbiological (photovoltaic, photonic, and field-effect transistor) systems.

A Surgical Case of Inferior Mesenteric Arteriovenous Malformation.

The treatment option for inferior mesenteric arteriovenous malformations is under debate because of the number of cases. We, herein, report about a 35-year-old man with congenital inferior mesenteric artery malformation (AVM) presenting with mucous stool and severe abdominal pain. The radical operation, after building the diverting stoma, minimized the extent of the resection. This is the first reported case where surgical management was used to control severe symptoms induced by inferior mesenteric AVM.

Safety and Efficacy of the Surgical Management of Hemodialysis Patients with Gastric Cancer.

This retrospective study evaluated the short- and long-term outcomes after surgical management for gastric cancer in hemodialysis patients compared to non-dialysis patients. Twelve hemodialysis patients were compared with a propensity score-matched cohort of 39 gastric cancer patients who had not undergone hemodialysis. Short- and long-term outcomes along with scores estimating physiological ability and surgical stress were evaluated in both groups. The incidence of postoperative morbidity according to the Clavien-Dindo classification was higher in the hemodialysis gastric cancer group than in the non-dialysis gastric cancer group. The 5-year overall survival rate in the non-dialysis group was 69.2% after surgical resection for gastric cancer and 22.2% in the hemodialysis group. Patients with preoperative risk scores≥0.48 had significantly poorer survival outcomes compared to those with preoperative risk scores<0.48 (5-year survival rate, 83.3% vs. 39.4%, respectively). Our analyses suggest that hemodialysis patients undergoing surgery for gastric cancer have a significantly poorer postoperative prognosis and an elevated risk of postoperative complications.