Faslpr gene dosage tunes the extent of lymphoproliferation and T cell differentiation in lupus.

Sle1 and Faslpr are two lupus susceptibility loci that lead to manifestations of systemic lupus erythematosus. To evaluate the dosage effects of Faslpr in determining cellular and serological phenotypes associated with lupus, we developed a new C57BL/6 (B6) congenic lupus strain, B6.Sle1/Sle1.Faslpr/+ (Sle1homo.lprhet) and compared it with B6.Faslpr/lpr (lprhomo), B6.Sle1/Sle1 (Sle1homo), and B6.Sle1/Sle1.Faslpr/lpr (Sle1homo.lprhomo) strains. Whereas Sle1homo.lprhomo mice exhibited profound lymphoproliferation and early mortality, Sle1homo.lprhet mice had a lifespan comparable to B6 mice, with no evidence of splenomegaly or lymphadenopathy. Compared to B6 monogenic lupus strains, Sle1homo.lprhet mice exhibited significantly elevated serum ANA antibodies and increased proteinuria. Additionally, Sle1homo.lprhet T cells had an increased propensity to differentiate into Th1 cells. Gene dose effects of Faslpr were noted in upregulating serum IL-1⍺, IL-2, and IL-27. Taken together, Sle1homo.lprhet strain is a new C57BL/6-based model of lupus, ideal for genetic studies, autoantibody repertoire investigation, and for exploring Th1 effector cell skewing without early-age lymphoproliferative autoimmunity.

Estrogen Inhibits Epithelial Progesterone Receptor-Dependent Progestin Therapy Efficacy in a Mouse Model of Cervical Cancer.

Although the uterine cervix responds to the female sex hormone change, the role of progesterone in cervical cancer is poorly understood. It has been shown that medroxyprogesterone acetate (MPA) regresses cervical cancer in the transgenic mouse model expressing human papillomavirus type 16 E6 and E7 oncogenes. As MPA interacts most strongly with progesterone receptor (PR), we reasoned that PR would contribute to MPA-induced regression of cervical cancer. We also hypothesized that estrogen influences the therapeutic activity of MPA because it promotes cervical cancer growth in the same mouse model. The present study showed that the deletion of Pgr in the cervical cancer cells ablated the MPA's therapeutic effect in the human papillomavirus transgenic mouse model. Additionally, estrogen attenuated cancer regression by MPA in the same model system. These observations indicate that MPA can effectively regress cervical cancer only when cancer cells express PR and estrogen levels are low. These results suggest that, if translatable, MPA should be administered when estrogen levels are low in patients with PR-positive cervical cancer.

Functional roles of female sex hormones and their nuclear receptors in cervical cancer.

There has been little progress for several decades in modalities to treat cervical cancer. While the cervix is a hormone-sensitive tissue, physiologic roles of estrogen receptor α (ERα), progesterone receptor (PR), and their ligands in this tissue are poorly understood. It has hampered critical assessments of data in early epidemiologic and clinical studies for cervical cancer. Experimental evidence obtained from studies using mouse models has provided new insights into the molecular mechanism of ERα and PR in cervical cancer. In a mouse model expressing human papillomavirus (HPV) oncogenes, exogenous estrogen promotes cervical cancer through stromal ERα. In the same mouse model, genetic ablation of PR promotes cervical carcinogenesis without exogenous estrogen. Medroxyprogesterone acetate, a PR-activating drug, regresses cervical cancer in the mouse model. These results support that ERα and PR play opposite roles in cervical cancer. They further support that ERα inhibition and PR activation may be translated into valuable treatment for a subset of cervical cancers.

Estrogen Receptor-α Suppresses Liver Carcinogenesis and Establishes Sex-Specific Gene Expression.

Estrogen protects females from hepatocellular carcinoma (HCC). To determine whether this protection is mediated by classic estrogen receptors, we tested HCC susceptibility in estrogen receptor-deficient mice. In contrast to a previous study, we found that diethylnitrosamine induces hepatocarcinogenesis to a significantly greater extent when females lack Esr1, which encodes Estrogen Receptor-α. Relative to wild-type littermates, Esr1 knockout females developed 9-fold more tumors. Deficiency of Esr2, which encodes Estrogen Receptor-ß, did not affect liver carcinogenesis in females. Using microarrays and QPCR to examine estrogen receptor effects on hepatic gene expression patterns, we found that germline Esr1 deficiency resulted in the masculinization of gene expression in the female liver. Six of the most dysregulated genes have previously been implicated in HCC. In contrast, Esr1 deletion specifically in hepatocytes of Esr1 conditional null female mice (in which Cre was expressed from the albumin promoter) resulted in the maintenance of female-specific liver gene expression. Wild-type adult females lacking ovarian estrogen due to ovariectomy, which is known to make females susceptible to HCC, also maintained female-specific expression in the liver of females. These studies indicate that Esr1 mediates liver cancer risk, and its control of sex-specific liver gene expression involves cells other than hepatocytes.

Non-Metabolic Functions of PKM2 Contribute to Cervical Cancer Cell Proliferation Induced by the HPV16 E7 Oncoprotein.

Pyruvate kinase M2 (PKM2) mainly catalyzes glycolysis, but it also exerts non-glycolytic functions in several cancers. While it has been shown to interact with the human papillomavirus 16 (HPV16) E7 oncoprotein, the functional significance of PKM2 in HPV-associated cervical cancer has been elusive. Here, we show that HPV16 E7 increased the expression of PKM2 in cervical cancer cells. TCGA data analyses revealed a higher level of PKM2 in HPV+ than HPV- cervical cancers and a worse prognosis for patients with high PKM2 expression. Functionally, we demonstrate that shRNA-mediated PKM2 knockdown decreased the proliferation of HPV+ SiHa cervical cancer cells. PKM2 knockdown also inhibited the E7-induced proliferation of cervical cancer cells. ML265 activating the pyruvate kinase function of PKM2 inhibited cell cycle progression and colony formation. ML265 treatments decreased phosphorylation of PKM2 at the Y105 position that has been associated with non-glycolytic functions. On the contrary, HPV16 E7 increased the PKM2 phosphorylation. Our results indicate that E7 increases PKM2 expression and activates a non-glycolytic function of PKM2 to promote cervical cancer cell proliferation.

Progesterone Receptor Is a Haploinsufficient Tumor-Suppressor Gene in Cervical Cancer.

Tumor-suppressor genes (TSG) are often deleted or transcriptionally suppressed in cancer. PGR codes for progesterone receptor (PR), a transcription factor whose function depends on its ligand. Although PR expression is often undetectable in cervical cancer, its relevance to the endocrine-related etiology of this prevalent gynecological disease remains unclear. In this study, we show that the deletion of one Pgr allele in cervical epithelium promoted spontaneous cervical cancer in human papilloma viral oncogene-expressing transgenic mice as efficiently as the ablation of both Pgr alleles. We also show that tumors arising in the transgenic mice with one or both Pgr alleles did not express PR or expressed at the reduced levels compared with the normal epithelium. PR status correlated with estrogen receptor α (ERα) status in the mouse model and the Cancer Genome Atlas (TCGA) dataset. TCGA data analyses revealed that PGR expression significantly decreased in cervical cancer and that the biallelic deletion of PGR was rare. Furthermore, low PGR expression was associated with poor prognosis in young patients with cervical cancer. These discoveries point to PGR as a haploinsufficient TSG in the uterine cervix. They also raise the possibility that the restoration of PGR expression may improve the survival rate. IMPLICATIONS: The decreased expression of PR may increase the risk of cervical cancer in human papillomavirus-infected women. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/19/1/42/F1.large.jpg.

Medroxyprogesterone Acetate Prevention of Cervical Cancer through Progesterone Receptor in a Human Papillomavirus Transgenic Mouse Model.

Cervical dysplastic lesions called cervical intraepithelial neoplasias (CINs) need be treated to prevent cervical cancer. Currently available surgical procedures are effective, but the development of noninvasive treatment is warranted. In human papillomavirus transgenic mice engineered to express human papillomavirus type 16 E6 and E7, short-term treatment with 17ß-estradiol induces CINs that progress to cervical cancer if the treatment is continued. In the present study, this mouse model was used to determine whether medroxyprogesterone acetate (MPA), a progestin drug, is chemopreventive. Human papillomavirus transgenic mice bearing CIN lesions were treated with MPA plus 17ß-estradiol. Unlike control mice treated with 17ß-estradiol alone, cervical cancer was absent in the MPA-treated mice. This observation suggests that MPA prevented CIN from progressing to invasive cancer. MPA was associated with inhibited cell proliferation and the promotion of apoptosis in CIN lesions. Confirming the role of the progesterone receptor, the preventive effect of MPA was absent in human papillomavirus transgenic mice in which the expression of progesterone receptor was genetically ablated. These results suggest that MPA is efficient in treating progesterone receptor-positive CIN lesions. These findings provide the basis for a biomarker-driven clinical trial of the secondary prevention of cervical cancer.

Epithelial oestrogen receptor α is dispensable for the development of oestrogen-induced cervical neoplastic diseases.

Human papillomavirus (HPV) is required but not sufficient for cervical carcinoma (CxCa) development. Oestradiol (E2 ) promotes CxCa development in K14E7 transgenic mice expressing the HPV16 E7 oncoprotein under the control of the keratin (K14) promoter. E2 mainly functions through oestrogen receptor α (ERα). However, the role of ERα in human CxCa has been underappreciated largely because it is not expressed in carcinoma cells. We have shown that deletion of Esr1 (the ERα-coding gene) in the cervical stroma of K14E7 mice promotes regression of cervical intraepithelial neoplasia (CIN), the precursor lesion of CxCa. Here, we deleted Esr1 in the cervical epithelium but not in the stroma. We found that E2 induced cervical epithelial cell proliferation in epithelial ERα-deficient mice. We also found that E2 promoted the development of CIN and CxCa in epithelial ERα-deficient K14E7 mice and that all neoplastic epithelial cells were negative for ERα. In addition, proliferation indices were similar between ERα- and ERα+ CxCa. These results indicate that epithelial ERα is not necessary for E2 -induced CIN and CxCa. Taking these findings together, we conclude that stromal ERα rather than epithelial ERα mediates oncogenic E2 signalling in CxCa. Our results support stromal ERα signalling as a therapeutic target for the disease. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Recurrence of cervical cancer and its resistance to progestin therapy in a mouse model.

Studies using K14E6/K14E7 transgenic mice expressing E6 and E7 oncoprotein of human papillomavirus type 16 (HPV16) have demonstrated that estrogen (E2) is required for the genesis and growth of cervical cancer. Our prior study using the same mouse model has showed that progestin drug medroxyprogesterone acetate (MPA) promotes regression of primary cervical cancer. In the present study, we use the same transgenic mouse model to determine whether the cancer recurs after MPA therapy. Cervical cancer recurred even if MPA treatment was continued. Unlike primary cervical cancer, the cancer recurred even in the absence of exogenous E2 when MPA treatment was ceased. Furthermore, recurrent cervical cancer did not fully regress upon MPA treatment. Our results support that MPA fails to completely eliminate primary cervical cancer cells and that remaining cancer cells grow independent of exogenous E2 and are refractory to MPA.

Distinct functions and regulation of epithelial progesterone receptor in the mouse cervix, vagina, and uterus.

While the function of progesterone receptor (PR) has been studied in the mouse vagina and uterus, its regulation and function in the cervix has not been described. We selectively deleted epithelial PR in the female reproductive tracts using the Cre/LoxP recombination system. We found that epithelial PR was required for induction of apoptosis and suppression of cell proliferation by progesterone (P4) in the cervical and vaginal epithelium. We also found that epithelial PR was dispensable for P4 to suppress apoptosis and proliferation in the uterine epithelium. PR is encoded by the Pgr gene, which is regulated by estrogen receptor α (ERα) in the female reproductive tracts. Using knock-in mouse models expressing ERα mutants, we determined that the DNA-binding domain (DBD) and AF2 domain of ERα were required for upregulation of Pgr in the cervix and vagina as well as the uterine stroma. The ERα AF1 domain was required for upregulation of Pgr in the vaginal stroma and epithelium and cervical epithelium, but not in the uterine and cervical stroma. ERα DBD, AF1, and AF2 were required for suppression of Pgr in the uterine epithelium, which was mediated by stromal ERα. Epithelial ERα was responsible for upregulation of epithelial Pgr in the cervix and vagina. Our results indicate that regulation and functions of epithelial PR are different in the cervix, vagina, and uterus.

Targeting female hormone receptors as cervical cancer therapy.

While preventive methods for cervical cancer are effective, available therapies for advanced cervical cancers are ineffective. New experimental evidence points to weaknesses of prior studies and provides fresh molecular insights on the opposing roles of estrogen receptor alpha (ERα) and the progesterone receptor (PR) that may be translated into valuable treatments for a subset of cervical cancers.

Recurrence of cervical cancer in mice after selective estrogen receptor modulator therapy.

Estrogen and its nuclear receptor, estrogen receptor α, are necessary cofactors in the initiation and multistage progression of carcinogenesis in the K14E6/E7 transgenic mouse model of human papillomavirus-associated cervical cancer. Recently, our laboratory reported that raloxifene, a selective estrogen receptor modulator, promoted regression of high-grade dysplasia and cancer that arose in the cervix of K14E6/E7 transgenic mice treated long-term with estrogen. Herein, we evaluated the recurrence of cervical cancer after raloxifene therapy in our preclinical model of human papillomavirus-associated cervical carcinogenesis. We observed recurrence of cervical cancer in mice re-exposed to estrogen after raloxifene treatment, despite evidence suggesting the antagonistic effects of raloxifene persisted in the reproductive tract after treatment had ceased. We also observed recurrence of neoplastic disease in mice that were not retreated with exogenous estrogen, although the severity of disease was less. Recurrent neoplastic disease and cancers retained functional estrogen receptor α and responded to retreatment with raloxifene. Moreover, continuous treatment of mice with raloxifene prevented the emergence of recurrent disease seen in mice in which raloxifene was discontinued. These data suggest that cervical cancer cells are not completely eradicated by raloxifene and rapidly expand if raloxifene treatment is ceased. These findings indicate that a prolonged treatment period with raloxifene might be required to prevent recurrence of neoplastic disease and lower reproductive tract cancers.

Requirement of estrogen receptor alpha DNA-binding domain for HPV oncogene-induced cervical carcinogenesis in mice.

Cervical cancer is caused by human papillomavirus (HPV) in collaboration with other non-viral factors. The uterine cervix is hormone responsive and female hormones have been implicated in the pathogenesis of the disease. HPV transgenic mice expressing HPV16 oncogenes E6 (K14E6) and/or E7 (K14E7) have been employed to study a mechanism of estrogen and estrogen receptor α (ERα) in cervical carcinogenesis. A chronic exposure to physiological levels of exogenous estrogen leads to cervical cancer in the HPV transgenic mice, which depends on ERα. The receptor is composed of multiple functional domains including a DNA-binding domain (DBD), which mediates its binding to estrogen-responsive elements (EREs) on target genes. A transcriptional control of genes by ERα is mediated by either DBD-dependent (classical) or DBD-independent (non-classical) pathway. Although molecular mechanisms of ERα in cancer have been characterized extensively, studies investigating importance of each pathway for carcinogenesis are scarce. In this study, we employ knock-in mice expressing an ERα DBD mutant (E207A/G208A) that is defective specifically for ERE binding. We demonstrate that the ERα DBD mutant fails to support estrogen-induced epithelial cell proliferation and carcinogenesis in the cervix of K14E7 transgenic mice. We also demonstrate that cervical diseases are absent in K14E7 mice when one ERα DBD mutant allele and one wild-type allele are present. We conclude that the ERα classical pathway is required for cervical carcinogenesis in a mouse model.

Progesterone signaling inhibits cervical carcinogenesis in mice.

Human papillomavirus is the main cause of cervical cancer, yet other nonviral cofactors are also required for the disease. The uterine cervix is a hormone-responsive tissue, and female hormones have been implicated in cervical carcinogenesis. A transgenic mouse model expressing human papillomavirus oncogenes E6 and/or E7 has proven useful to study a mechanism of hormone actions in the context of this common malignancy. Estrogen and estrogen receptor α are required for the development of cervical cancer in this mouse model. Estrogen receptor α is known to up-regulate expression of the progesterone receptor, which, on activation by its ligands, either promotes or inhibits carcinogenesis, depending on the tissue context. Here, we report that progesterone receptor inhibits cervical and vaginal epithelial cell proliferation in a ligand-dependent manner. We also report that synthetic progestin medroxyprogesterone acetate promotes regression of cancers and precancerous lesions in the female lower reproductive tracts (ie, cervix and vagina) in the human papillomavirus transgenic mouse model. Our results provide the first experimental evidence that supports the hypothesis that progesterone signaling is inhibitory for cervical carcinogenesis in vivo.

Estradiol and tamoxifen regulate NRF-1 and mitochondrial function in mouse mammary gland and uterus.

Nuclear respiratory factor-1 (NRF-1) stimulates the transcription of nuclear-encoded genes that regulate mitochondrial (mt) genome transcription and biogenesis. We reported that estradiol (E2) and 4-hydroxytamoxifen (4-OHT) stimulate NRF-1 transcription in an estrogen receptor α (ERα)- and ERß-dependent manner in human breast cancer cells. The aim of this study was to determine whether E2 and 4-OHT increase NRF-1 in vivo. Here, we report that E2 and 4-OHT increase NRF-1 expression in mammary gland (MG) and uterus of ovariectomized C57BL/6 mice in a time-dependent manner. E2 increased NRF-1 protein in the uterus and MG; however, in MG, 4-OHT increased Nrf1 mRNA but not protein. Chromatin immunoprecipitation assays revealed increased in vivo recruitment of ERα to the Nrf1 promoter and intron 3 in MG and uterus 6 h after E2 and 4-OHT treatment, commensurate with increased NRF-1 expression. E2- and 4-OHT-induced increases in NRF-1 and its target genes Tfam, Tfb1m, and Tfb2m were coordinated in MG but not in uterus due to uterine-selective inhibition of the expression of the NRF-1 coactivators Ppargc1a and Ppargc1b by E2 and 4-OHT. E2 transiently increased NRF-1 and PGC-1α nuclear staining while reducing PGC-1α in uterus. E2, not 4-OHT, activates mt biogenesis in MG and uterus in a time-dependent manner. E2 increased mt outer membrane Tomm40 protein levels in MG and uterus whereas 4-OHT increased Tomm40 only in uterus. These data support the hypothesis of tissue-selective regulation of NRF-1 and its downstream targets by E2 and 4-OHT in vivo.

Requirement for stromal estrogen receptor alpha in cervical neoplasia.

The major etiological factor for cervical cancer is the high-risk human papillomavirus (HPV), which encodes E6 and E7 oncogenes. However, HPV is not sufficient, and estrogen has been proposed as an etiological cofactor for the disease. Its requirement has been demonstrated in mouse models for HPV-associated cervical cancer (e.g., K14E7 transgenic mice). Although germline knockout of estrogen receptor alpha (ERα) renders mice resistant to cervical cancer, the cell-type-specific requirement for ERα is not known. In this study, we demonstrate that temporal deletion of stromal ERα induced complete regression of cervical dysplasia in K14E7 mice. Our results strongly support the hypothesis that stromal ERα is necessary for HPV-induced cervical carcinogenesis and implicate paracrine mechanisms involving ERα signaling in the development of estrogen-dependent cervical cancers. This is the first evidence to support the importance of stromal ERα in estrogen-dependent neoplastic disease of the female reproductive tract.

The E6 oncoprotein from HPV16 enhances the canonical Wnt/ß-catenin pathway in skin epidermis in vivo.

The contribution of the Wnt signaling pathway to human papilloma virus (HPV)-induced carcinogenesis is poorly understood. In high-grade dysplastic lesions that are caused by high-risk HPVs (HR-HPV), ß-catenin is often located in the cell nucleus, which suggests that Wnt pathway may be involved in the development of HPV-related carcinomas. Most of the oncogenic potential of HR-HPVs resides on the PDZ-binding domain of E6 protein. We hypothesized that the PDZ-binding domain of the HPV16-E6 oncoprotein induces the nuclear accumulation of ß-catenin due to its capacity to degrade PDZ-containing cellular targets. To test this hypothesis, we evaluated the staining pattern of ß-catenin in the skin epidermis of transgenic mice expressing the full-length E6 oncoprotein (K14E6 mice) and measured LacZ gene expression in K14E6 mice that were crossed with a strain expressing LacZ that was knocked into the Axin2 locus (Axin2(+/LacZ) mice). Here, we show that the E6 oncoprotein enhances the nuclear accumulation of ß-catenin, the accumulation of cellular ß-catenin-responsive genes, and the expression of LacZ. None of these effects were observed when a truncated E6 oncoprotein that lacks the PDZ-binding domain was expressed alone (K14E6ΔPDZ mice) or in combination with Axin2(+/LacZ). Conversely, cotransfection with either E6 or E6ΔPDZ similarly enhanced canonical Wnt signaling in short-term in vitro assays that used a luciferase Wnt/ß-catenin/TCF-dependent promoter. We propose that the activation of canonical Wnt signaling could be induced by the HPV16-E6 oncoprotein; however, the participation of the E6 PDZ-binding domain seems to be important in in vivo models only.

Estrogen and ERalpha: culprits in cervical cancer?

Estrogen and its receptors are implicated in the promotion and prevention of various cancers. Although the uterine cervix is highly responsive to estrogen, the role of estrogen in cervical cancer, which is strongly associated with human papillomavirus (HPV) infections, is poorly understood. Recent studies in HPV transgenic mouse models provide evidence that estrogen and its nuclear receptor promote cervical cancer in combination with HPV oncogenes. Although epidemiological studies further support this hypothesis, there is little experimental data assessing the hormonal responsiveness of human cervical cancers. If these cancers are dependent on estrogen, then drugs targeting estrogen and its receptors could be effective in treating and/or preventing cervical cancer, the second leading cause of death by cancer among women worldwide.

Prevention and treatment of cervical cancer in mice using estrogen receptor antagonists.

The majority of human cervical cancers are associated with the high-risk human papillomavirus (HPV) types. In mouse models for HPV-associated cancers, estrogen is required for the development of cervical and vaginal cancers. The estrogen receptor alpha (ERalpha) also is required in mice for these cancers to arise. These data are consistent with the observation in women that long-term use of oral contraceptives or multiple pregnancies significantly increases the risk for cervical cancer in HPV-positive women. In the present study, we examined whether drugs that interfere with the function of ERalpha are effective in treating and/or preventing cervical cancer in mice. We provide evidence that a complete ER antagonist, ICI 182,780 (ICI), as well as a selective ER modulator, raloxifene, efficiently clear cancer and its precursor lesions in both the cervix and the vagina. Furthermore, ICI was capable of preventing the onset of cancers in mice bearing precursor lesions. These findings point to the potential value of ER antagonists in controlling gynecological disease in the lower reproductive tracts in women.

Requirement for estrogen receptor alpha in a mouse model for human papillomavirus-associated cervical cancer.

The majority of human cervical cancers are associated with the high-risk human papillomaviruses (HPV), which encode the potent E6 and E7 oncogenes. On prolonged treatment with physiologic levels of exogenous estrogen, K14E7 transgenic mice expressing HPV-16 E7 oncoprotein in their squamous epithelia succumb to uterine cervical cancer. Furthermore, prolonged withdrawal of exogenous estrogen results in complete or partial regression of tumors in this mouse model. In the current study, we investigated whether estrogen receptor alpha (ERalpha) is required for the development of cervical cancer in K14E7 transgenic mice. We show that exogenous estrogen fails to promote either dysplasia or cervical cancer in K14E7/ERalpha-/- mice despite the continued presence of the presumed cervical cancer precursor cell type, reserve cells, and evidence for E7 expression therein. We also observed that cervical cancers in our mouse models are strictly associated with atypical squamous metaplasia (ASM), which is believed to be the precursor for cervical cancer in women. Consistently, E7 and exogenous estrogen failed to promote ASM in the absence of ERalpha. We conclude that ERalpha plays a crucial role at an early stage of cervical carcinogenesis in this mouse model.