Mouse models of epithelial ovarian cancer for preclinical studies

Epithelial ovarian cancer(EOC) is the leading cause of gynecological cancer-related mortality in the developed world. EOC is a heterogeneous disease represented by several histological and molecular subtypes. Therefore, exploration of relevant preclinical animal models that consider the heterogenic nature of EOC is of great importance for the development of novel therapeutic strategies that can be translated clinically to combat this devastating disease. In this review, we discuss recent progress in the development of preclinical mouse models for EOC study as well as their advantages and limitations.

绝缘子在果蝇体内启动子靶向性序列(PTS)中的功能研究

在复杂基因组中,绝缘子形成了染色质区域的边界,阻止邻近的基因上的增强子对这些启动子进行不必要的激活。果蝇双胸复合体的Abd-B基因区域的启动子靶向序列(promoter targeting sequence,PTS)能够克服一个绝缘子的作用,并且推动和限制单个启动子的作用。研究发现这个启动子靶向序列活性的建立需要一个绝缘子对它进行激活,但是无需这个绝缘子存在就可以持续下去。这些结果表明启动子靶向序列的建立是不依赖于增强子活性的,是通过发育和后代繁衍的表观遗传保持下去的。

Selective recruitment of host factors by HSV-1 replication centers

Herpes simplex virus type 1（HSV-1） enters productive infection after infecting epithelial cells, where it controls the host nucleus to make viral proteins, starts viral DNA synthesis and assembles infectious virions. In this process, replicating viral genomes are organized into replication centers to facilitate viral growth. HSV-1 is known to use host factors, including host chromatin and host transcription regulators, to transcribe its genes; however, the invading virus also encounters host defense and stress responses to inhibit viral growth. Recently, we found that HSV-1 replication centers recruit host factor CTCF but exclude γH2A.X. Thus, HSV-1 replication centers may selectively recruit cellular factors needed for viral growth, while excluding host factors that are deleterious for viral transcription or replication. Here we report that the viral replication centers selectively excluded modified histone H3, including heterochromatin mark H3K9me3, H3S10 P and active chromatin mark H3K4me3, but not unmodified H3. We found a dynamic association between the viral replication centers and host RNA polymerase II. The centers also recruited components of the DNA damage response pathway, including 53BP1, BRCA1 and host antiviral protein SP100. Importantly, we found that ATM kinase was needed for the recruitment of CTCF to the viral centers. These results suggest that the HSV-1 replication centers took advantage of host signaling pathways to actively recruit or exclude host factors to benefit viral growth.

Common genetic variants in the TP53 pathway and their impact on cancer

The TP53 gene is well known to be the most frequently mutated gene in human cancer.In addition to mutations,there are > 20 different coding region single-nucleotide polymorphisms (SNPs) in the TP53 gene,as well as SNPs in MDM2,the negative regulator of p53.Several of these SNPs are known to alter p53 pathway function.This makes p53 rather unique among cancer-critical genes,e.g.the coding regions of other cancer-critical genes like Ha-Ras,RB,and PI3KCA do not have non-synonymous coding region SNPs that alter their function in cancer.The next frontier in p53 biology will consist of probing which of these coding region SNPs are moderately or strongly pathogenic and whether they influence cancer risk and the efficacy of cancer therapy.The challenge after that will consist of determining whether we can tailor chemotherapy to correct the defects for each ofthese variants.Here we review the SNPs in TP53 and MDM2 that show the most significant impact on cancer and other diseases.We also propose avenues for how this information can be used to better inform personalized medicine approaches to cancer and other diseases.

Hepatitis B virus molecular biology and pathogenesis

As obligate intracellular parasites,viruses need a host cell to provide a milieu favorable to viral replication.Consequently,viruses often adopt mechanisms to subvert host cellular signaling processes.While beneficial for the viral replication cycle,virus-induced deregulation of host cellular signaling processes can be detrimental to host cell physiology and can lead to virus-associated pathogenesis,including,for oncogenic viruses,cell transformation and cancer progression.Included among these oncogenic viruses is the hepatitis B virus(HBV).Despite the availability of an HBV vaccine,350-500 million people worldwide are chronically infected with HBV,and a significant number of these chronically infected individuals will develop hepatocellular carcinoma(HCC).Epidemiological studies indicate that chronic infection with HBV is the leading risk factor for the development of HCC.Globally,HCC is the second highest cause of cancer-associated deaths,underscoring the need for understanding mechanisms that regulate HBV replication and the development of HBV-associated HCC.HBV is the prototype member of the Hepadnaviridae family;members of this family of viruses have a narrow host range and predominately infect hepatocytes in their respective hosts.The extremely small and compact hepadnaviral genome,the unique arrangement of open reading frames,and a replication strategy utilizing reverse transcription of an RNA intermediate to generate the DNA genome are distinguishing features of the Hepadnaviridae.In this review,the authors provide a comprehensive description of HBV biology,summarize the model systems used for studying HBV infections,and highlight potential mechanisms that link a chronic HBV-infection to the development of HCC.For example,the HBV X protein(HBx),a key regulatory HBV protein that is important for HBV replication,is thought to play a cofactor role in the development of HBV-induced HCC,and the authors highlight the functions of HBx that may contribute to the development of HBV-associated HCC.

Induction of metallothionein expression during monocyte to melanoma-associated macrophage differentiation

Tumor-associated macrophages （TAMs） play a critical role in melanoma growth and metastasis. Infiltration of TAMs correlates with the poor prognosis of melanoma. TAMs are differentiated from monocytes in response to the tumor microenvironment cue. However, the mechanism how TAMs adapt to the tumor microenvironment after differentiation from monocytes is not fully understood. In addition, specific identification of TAMs in melanoma is difficult because the expression of the most commonly used macrophage marker, CD68, is also expressed in melanoma cells. In an earlier study, we found by gene microarray analysis that seven members of the metallothionein （MTs） family were upregulated in melanoma-conditioned medium induced macrophages （MCIM-MO）. MTs have been implicated in zinc metabolism and inflammation. In the present study, we confirmed that expression of metallothionein is induced in M-CSF differentiated macrophages （M-CSF/M~） and MCIM-M~ at both the mRNA and protein levels using real-time PCR, immunofluorescence, and western blot analysis. Furthermore, we demonstrated the presence of metallothionein in melanoma tissues in vivo and that metallothionein was co-localized with TAMs markers, CD68 and CD163. Finally, we demonstrated the induction of the zinc importer gene Zip8 both in M-CSF/MO and MCIM-MO. Our study identifies metallothionein as a novel marker for TAMs and suggests that metaliothionein might play important roles in macrophage adaptation and function in the tumor microenvironment.

Tumor cell-intrinsic PD-L1 promotes tumor-initiating cellgeneration and functions in melanoma and ovarian cancer

As tumor PD-L1 provides signals to anti-tumor PD-1^(+)T cells that blunt their functions,αPD-1 andαPD-L1 antibodies have been developed as anti-cancer immunotherapies based on interrupting this signaling axis.However,tumor cell-intrinsic PD-L1 signals also regulate immune-independent tumor cell proliferation and mTOR signals,among other important effects.Tumor-initiating cells(TICs)generate carcinomas,resist treatments and promote relapse.We show here that in murine B16 melanoma and ID8agg ovarian carcinoma cells,TICs express more PD-L1 versus non-TICs.Silencing PD-L1 in B16 and ID8agg cells by shRNA(‘PD-L1lo’)reduced TIC numbers,the canonical TIC genes nanog and pou5f1(oct4),and functions as assessed by tumorosphere development,immune-dependent and immune-independent tumorigenesis,and serial transplantability in vivo.Strikingly,tumor PD-L1 sensitized TIC to interferon-γand rapamycin in vitro.Cell-intrinsic PD-L1 similarly drove functional TIC generation,canonical TIC gene expression and sensitivity to interferon-γand rapamycin in human ES2 ovarian cancer cells.Thus,tumor-intrinsic PD-L1 signals promote TIC generation and virulence,possibly by promoting canonical TIC gene expression,suggesting that PD-L1 has novel signaling effects on cancer pathogenesis and treatment responses.

STING regulates BCR signaling in normal and malignant B cells

STING is an endoplasmic reticulum(ER)-resident protein critical for sensing cytoplasmic DNA and promoting the production of type Ⅰ interferons;however,the role of STING in B cell receptor(BCR)signaling remains unclear.We generated STING V154M knock-in mice and showed that B cells carrying constitutively activated STING specifically degraded membrane-bound IgM,Ig a and Igβ via SEL1L/HRD1-mediated ER-associated degradation(ERAD).B cells with activated STING were thus less capable of responding to BCR activation by phosphorylating Igα and Syk than those without activated STING.When immunized with T-independent antigens,STING V154M mice produced significantly fewer antigen-specific plasma cells and antibodies than immunized wild-type(WT)mice.We further generated B cell-specific STING^(KO) mice and showed that STING^(KO) B cells indeed responded to activation by transducing stronger BCR signals than their STING-proficient counterparts.When B cell-specific STING^(KO) mice were T-independently immunized,they produced significantly more antigen-specific plasma cells and antibodies than immunized STIN^(WT)mice.Since both human and m ouse IGHV-unmutated malignant chronic lymphocytic leukemia(CLL)cells downregulated the expression of STING,we explored whether STING downregulation could contribute to the well-established robust BCR signaling phenotype in malignant CLL cells.We generated a STING-deficient CLL mouse model and showed that STING-deficient CLL cells were indeed more responsive to BCR activation than their STING-proficient counterparts.These results revealed a novel B cell-intrinsic role of STING in negatively regulating BCR signaling in both normal and malignant B cells.

STING negatively regulates allogeneic T-cell responses by constraining antigen-presenting cell function

Stimulator of interferon genes(STING)-mediated innate immune activation plays a key role in tumor-and self-DNA-elicited antitumor immunity and autoimmunity.However,STING can also suppress tumor immunity and autoimmunity.STING signaling In host nonhematopoietic cells was reported to either protect against or promote graft-versus-host disease(GVHD),a major complication of allogeneic hematopoietic cell transplantation(allo-HCT).Host hematopoietic antigen-presenting cells(APCs)play key roles in donor T-cell priming during GVHD initiation.However,how STING regulates host hematopoietic APCs after allo-HCT remains unknown.We utilized murine models of allo-HCT to assess the role of STING in hematopoietic APCs.STING-deficient recipients developed more severe GVHD after major histocompatibility complex-mismatched allo-HCT.Using bone marrow chimeras,we found that STING deficiency in host hematopoietic cells was primarily responsible for exacerbating the disease.Furthermore,STING on host CD11c+cells played a dominant role in suppressing allogeneic T-cell responses.Mechanistically,STING deficiency resulted in increased survival,activation,and function of APCs,including macrophages and dendritic cells.Consistently,constitutive activation of STING attenuated the survival,activation,and function of APCs isolated from STING V154M knock-in mice.STING-deficient APCs augmented donor T-cell expansion,chemokine receptor expression,and migration into intestinal tissues,resulting in accelerated/exacerbated GVHD.Using pharmacologic approaches,we demonstrated that systemic administration of a STING agonist(bis-(3'-5')-cyclic dimeric guanosine monophosphate)to recipient mice before transplantation significantly reduced GVHD mortality.In conclusion,we revealed a novel role of STING in APC activity that dictates T-cell allogeneic responses and validated STING as a potential therapeutic target for controlling GVHD after allo-HCT.