The Rfg1 and Bcr1 transcription factors regulate acidic pH-induced filamentous growth in Candida albicans.

IMPORTANCE: Candida albicans is a human commensal and frequent pathogen that encounters a wide range of pH stresses. The ability of C. albicans to adapt to changes in extracellular pH is crucial for its success in colonization and pathogenesis. The Rim101 pH sensing pathway is well known to govern neutral-alkaline pH responses in this pathogen. Here, we report a novel Rfg1-Bcr1 regulatory pathway that governs acidic pH responses and regulates filamentous growth in C. albicans. In addition, the Rim101-Phr1 pathway, cAMP signaling pathway, transcription factors Efg1 and Flo8, and hyphal-specific G1 cyclin Hgc1 cooperate with this regulation. Our findings provide new insights into the regulatory mechanism of acidic pH response in C. albicans.

Methylation of KRAS by SETD7 promotes KRAS degradation in non-small cell lung cancer.

Oncogenic KRAS mutations are a key driver for initiation and progression in non-small cell lung cancer (NSCLC). However, how post-translational modifications (PTMs) of KRAS, especially methylation, modify KRAS activity remain largely unclear. Here, we show that SET domain containing histone lysine methyltransferase 7 (SETD7) interacts with KRAS and methylates KRAS at lysines 182 and 184. SETD7-mediated methylation of KRAS leads to degradation of KRAS and attenuation of the RAS/MEK/ERK signaling cascade, endowing SETD7 with a potent tumor-suppressive role in NSCLC, both in vitro and in vivo. Mechanistically, RABGEF1, a ubiquitin E3 ligase of KRAS, is recruited and promotes KRAS degradation in a K182/K184 methylation-dependent manner. Notably, SETD7 is inversely correlated with KRAS at the protein level in clinical NSCLC tissues. Low SETD7 or RABGEF1 expression is associated with poor prognosis in lung adenocarcinoma patients. Altogether, our results define a tumor-suppressive function of SETD7 that operates via modulating KRAS methylation and degradation.

Sub-lethal concentrations of chlorhexidine inhibit Candida albicans growth by disrupting ROS and metal ion homeostasis.

Candida albicans is a normal resident of the human oral cavity. It is also the most common fungal pathogen, causing various oral diseases, particularly in immunocompromised individuals. Chlorhexidine digluconate (CHG) is a broad-spectrum antimicrobial agent widely used in dental practice and has been recommended to treat oral candidiasis. However, its action mechanism against the fungal pathogen C. albicans remains poorly understood. The aim of the present study was to investigate the effect of CHG at sub-lethal concentrations against C. albicans. CHG inhibited the growth of C. albicans in a dose- and time-dependent manner. Cells treated with CHG exhibited altered membrane permeability, reduced metabolic activity, and enhanced metal ion and reactive oxygen species (ROS) accumulation. Copper-sensing transcription factor Mac1, iron-sensing transcription factors Sfu1 and Sef2, and copper transporter Ctr1 regulated intracellular metal ion and ROS homeostasis in response to CHG. Deletion of MAC1, SFU1, or SEF2 increased intracellular ROS production and cell susceptibility to CHG. This study revealed a novel mechanism by which CHG induced apoptosis of C. albicans cells through the disruption of metal ion and ROS homeostasis, which may help to identify new targets for fungal infections.

Dezocine induces apoptosis in human cervical carcinoma Hela cells via the endoplasmic reticulum stress pathway.

Dezocine, a dual agonist and antagonist of the µ-opioid receptor and κ-opioid receptor, is widely used as an analgesic in China. At present, there are few studies on anti-tumor effects of dezocine, most of which are used to treat cancer pain. However, it has recently been reported that dezocine can induce apoptosis of triple negative breast cancer cells. Dezocine may have some anti-tumor activity, but the effect and potential mechanism of dezocine in the treatment of other types of cancer remain to be fully studied. The purpose of the present study was to investigate the effect of dezocine on human Hela cervical carcinoma cells, and to elucidate the underlying molecular mechanisms. We performed CCK-8 assays, clone formation assays, xenograft, flow cytometry analysis, western blot and RNA-seq analysis to evaluate the effects of dezocine on Hela cells. In addition, the role of endoplasmic reticulum (ER) stress in dezocine-induced apoptosis was investigated using qPCR and western blot analysis. Dezocine inhibited Hela cell viability in dose-dependent and time-dependent manners, and notably did not achieve this effect by targeting the opioid receptors. Further mechanistic studies demonstrated that dezocine activated ER stress by upregulating the expression of GRP78, IRE1 and p-JNK, and that dezocine-induced apoptosis was attenuated when the ER stress pathway was blocked. Our results provide a foundation to support the redefinition of dezocine as a novel, adjuvant treatment for patients with cervical cancer, although further research will be required to support its application in clinical practice.

Remodeling of dermal adipose tissue alleviates cutaneous toxicity induced by anti-EGFR therapy.

Anti-epidermal growth factor receptor (EGFR) therapy-associated cutaneous toxicity is a syndrome characterized by papulopustular rash, local inflammation, folliculitis, and microbial infection, resulting in a decrease in quality of life and dose interruption. However, no effective clinical intervention is available for this adverse effect. Here, we report the atrophy of dermal white adipose tissue (dWAT), a highly plastic adipose tissue with various skin-specific functions, correlates with rash occurrence and exacerbation in a murine model of EGFR inhibitor-induced rash. The reduction in dWAT is due to the inhibition of adipogenic differentiation by defects in peroxisome proliferator-activated receptor γ (PPARγ) signaling, and increased lipolysis by the induced expression of the lipolytic cytokine IL6. The activation of PPARγ by rosiglitazone maintains adipogenic differentiation and represses the transcription of IL6, eventually improving skin functions and ameliorating the severity of rash without altering the antitumor effects. Thus, activation of PPARγ represents a promising approach to ameliorate cutaneous toxicity in patients with cancer who receive anti-EGFR therapy.

Streptococcus mutans suppresses filamentous growth of Candida albicans through secreting mutanocyclin, an unacylated tetramic acid.

Fungi and bacteria often co-exist and physically or chemically interact with each other in their natural niches. This inter-kingdom species interaction is exemplified by the gram-positive bacterial pathogen Streptococcus mutans and opportunistic fungal pathogen Candida albicans, which co-exist in the human mouth. It has been demonstrated that the dynamic interaction between these two species plays a critical role in their virulence and biofilm development. In this study, we discovered that S. mutans represses filamentous development and virulence in C. albicans through secreting a secondary metabolite, mutanocyclin (a tetramic acid). Mutanocyclin functions by regulating the PKA catabolic subunit Tpk2 and its preferential binding target Sfl1. Inactivation of Tpk2 in C. albicans results in an increased sensitivity to mutanocyclin, whereas overexpression of Tpk2 leads to an increased resistance. Dysfunction of SFL1 and its downstream target genes overrides the hyphal growth defect caused by mutanocyclin. Further investigation demonstrates that three glycosylphosphatidylinositol (GPI)-anchored proteins (Spr1, Hyr4, and Iff8), associated with cell wall biogenesis and remodeling, and a set of filamentous regulators also contribute to the mutanocyclin response. We propose that both transcriptional regulation and cell wall composition contribute to mutanocyclin-mediated filamentous inhibition. This repressive effect of mutanocyclin could function as a natural regulator of filamentous development in C. albicans.

GPCR-mediated EGFR transactivation ameliorates skin toxicities induced by afatinib.

Many G-protein-coupled receptor (GPCR) agonists have been studied for transactivating epidermal growth factor receptor (EGFR) signaling through extracellular or intracellular pathways. Accumulated evidence has confirmed that GPCR transactivation participates in various diseases. However, the clinical application of GPCR transactivation has not been explored, and more translational studies are needed to develop therapies to target GPCR-mediated EGFR transactivation. In cancer patients treated with EGFR inhibitors (EGFRi), especially afatinib, a unique acneiform rash is frequently developed. In this study, we first established the connection between GPCR transactivation and EGFRi-induced skin disease. We examined the ability of three different GPCR agonists to reverse signaling inhibition and ameliorate rash induced by EGFRi. The activation of different agonists follows unique time and kinase patterns. Rats treated with EGFRi show a similar skin phenotype, with rash occurring in the clinic; correspondingly, treatment with GPCR agonists reduced keratinocyte apoptosis, growth retardation and infiltration of inflammatory cytokines by transactivation. This phenomenon demonstrates that EGFR inhibition in keratinocytes regulates key factors associated with rash. Our findings indicate that maintaining EGFR signaling by GPCR agonists might provide a possible therapy for EGFR inhibitor-induced skin toxicities. Our study provides the first example of the translational application of GPCR transactivation in treating diseases.

Phenotypic Switching and Filamentation in Candida haemulonii, an Emerging Opportunistic Pathogen of Humans.

Phenotypic plasticity is a common strategy adopted by fungal pathogens to adapt to diverse host environments. Candida haemulonii is an emerging multidrug-resistant human pathogen that is closely related to Candida auris. Until recently, it was assumed that C. haemulonii is incapable of phenotypic switching or filamentous growth. In this study, we report the identification of three distinct phenotypes in C. haemulonii: white, pink, and filament. The white and pink phenotypes differ in cellular size, colony morphology, and coloration on phloxine B- or CuSO4-containing agar. Switching between the white and pink cell types is heritable and reversible and is referred to as "the primary switching system." The additional switch phenotype, filament, has been identified and exhibits obviously filamentous morphology when grown on glycerol-containing medium. Several unique characteristics of the filamentous phenotype suggest that switching from or to this phenotype poses as a second yeast-filament switching system. The yeast-filament switch is nonheritable and temperature-dependent. Low temperatures favor the filamentous phenotype, whereas high temperatures promote filament-yeast transition. We further demonstrated that numerous aspects of the distinct cell types differ in numerous biological aspects, including their high temperature response, specific gene expression, CuSO4 tolerance, secreted aspartyl protease (SAP) activity, and virulence. Therefore, transition among the three phenotypes could enable C. haemulonii to rapidly adapt to, survive, and thrive in certain host niches, thereby contributing to its virulence. IMPORTANCE The capacity to switch between distinct cell types, known as phenotypic switching, is a common strategy adopted by Candida species to adapt to diverse environments. Despite considerable studies on phenotypic plasticity of various Candida species, Candida haemulonii is considered to be incapable of phenotypic switching or filamentous growth. Here, we report and describe filamentation and three distinct phenotypes (white, pink, and filament) in C. haemulonii. The three cell types differ in cellular and colony appearance, gene expression profiles, CuSO4 tolerance, and virulence. C. haemulonii cells switch heritably and reversibly between white and pink cell types, which is referred to as the "primary switching system." Switching between pink and filamentous phenotypes is nonheritable and temperature-dependent, representing a second switching system. As in other Candida species, switching among distinct morphological types may provide C. haemulonii with phenotypic plasticity for rapid responses to the changing host environment, and may contribute to its virulence.

Dezocine, An Opioid Analgesic, Exerts Antitumor Effects in Triple-Negative Breast Cancer by Targeting Nicotinamide Phosphoribosyltransferase.

Opioids are a potential adjuvant treatment for certain cancers; while they are primarily used to relieve chronic pain, these drugs may also affect cancer progression and recurrence. Dezocine is one opioid commonly used in China, but its effects on cancer cells are unknown. Here, we demonstrated the inhibitory effect of dezocine on triple-negative breast cancer (TNBC) cells, and determined the underlying molecular mechanism. We found that dezocine suppressed cell proliferation, migration and invasion, and induced apoptosis in TNBC cells. Xenograft models demonstrated the inhibitory effects of dezocine treatment on TNBC tumor growth in vivo. The anticancer effects of dezocine were independent of opioid receptors, which are not highly expressed by normal breast or breast cancer tissues. A pull-down assay and LC-MS/MS analysis indicated that dezocine directly targets NAMPT: computer modeling verified that the free energy of dezocine kinetically bound into the pocket of NAMPT was -17.4 kcal/mol. Consequently, dezocine treatment inhibited NAMPT enzyme activity, resulting in cellular NAD abolishment. We confirmed the dezocine-induced inhibition of cell proliferation by both NAMPT knockdown and upon treatment with the inhibitor FK866. Our results suggest that both dezocine and NAMPT might represent novel therapeutic targets for TNBC.

Defective N/S-Codoped 3D Cheese-Like Porous Carbon Nanomaterial toward Efficient Oxygen Reduction and Zn-Air Batteries.

Developing a facile and cost-efficient method to synthesize carbon-based nanomaterials possessing excellent structural and functional properties has become one of the most attractive topics in energy conversion and storage fields. In this study, density functional theory calculation results reveal the origin of high oxygen reduction reaction (ORR) activity predominantly derived from the synergistic effect of intrinsic defects and heteroatom dopants (e.g., N, S) that modulate the bandgap and charge density distribution of carbon matrix. Under the guidance of the first-principle prediction, by using ultralight biomass waste as precursor of C, N, and S elements, a defect-rich and N/S dual-doped cheese-like porous carbon nanomaterial is successfully designed and constructed. Herein, the intrinsic defects are artfully generated in terms of alkaline and ammonia activation. The electrochemical measurements display that such a material owns a comparable ORR activity (E1/2  = 0.835 V) to the commercial Pt/C catalyst, along with splendid durability and methanol tolerance in alkali media. Furthermore, as cathode catalyst, it displays a high Zn-air battery performance. The excellent ORR activity of the catalyst can be attributed to its unique 3D porous architecture, abundant intrinsic defects, and high-content active heteroatom dopants in the carbon matrix.

Recent progress in circular RNAs in human cancers.

Circular RNAs (circRNAs) are a large class of endogenous RNAs, formed by exon skipping or back-splicing events as covalently closed loops, which are expressed abundantly in mammalian cells. Although their biological functions remain largely unknown, recent studies show that circRNAs have three main functions in mammalian cells. First, circRNAs can regulate transcription and RNA splicing. Second, circRNAs function as microRNA (miRNA) sponges. Third, they can be translated into protein driven by N6-methyladenosine modification. Taking advantage of RNA sequencing (RNA-seq) technology, the expressions of circRNAs were found to be dysregulated in all types of cancer cell lines, tumor tissues, and even plasma samples from patients, which correlated with certain clinical characteristics, suggesting the potential roles of circRNAs in tumor progression. Considering their conserved sequences and stable structures, circRNAs were deemed to be promising biomarkers for the early diagnosis and prognosis prediction of cancer. In this review, we describe briefly the formation and properties of circRNAs, and focus mainly on recent progress in research into their function, regulation, and clinical relevance in different cancers.