IL-1ß expression in bone marrow dendritic cells is induced by TLR2 agonists and regulates HSC function.

Hematopoietic stem/progenitor cells (HSPCs) reside in localized microenvironments, or niches, in the bone marrow that provide key signals regulating their activity. A fundamental property of hematopoiesis is the ability to respond to environmental cues such as inflammation. How these cues are transmitted to HSPCs within hematopoietic niches is not well established. Here, we show that perivascular bone marrow dendritic cells (DCs) express a high basal level of Toll-like receptor-1 (TLR1) and TLR2. Systemic treatment with a TLR1/2 agonist induces HSPC expansion and mobilization. It also induces marked alterations in the bone marrow microenvironment, including a decrease in osteoblast activity and sinusoidal endothelial cell numbers. TLR1/2 agonist treatment of mice in which Myd88 is deleted specifically in DCs using Zbtb46-Cre show that the TLR1/2-induced expansion of multipotent HPSCs, but not HSPC mobilization or alterations in the bone marrow microenvironment, is dependent on TLR1/2 signaling in DCs. Interleukin-1ß (IL-1ß) is constitutively expressed in both murine and human DCs and is further induced after TLR1/2 stimulation. Systemic TLR1/2 agonist treatment of Il1r1-/- mice show that TLR1/2-induced HSPC expansion is dependent on IL-1ß signaling. Single-cell RNA-sequencing of low-risk myelodysplastic syndrome bone marrow revealed that IL1B and TLR1 expression is increased in DCs. Collectively, these data suggest a model in which TLR1/2 stimulation of DCs induces secretion of IL-1ß and other inflammatory cytokines into the perivascular niche, which in turn, regulates multipotent HSPCs. Increased DC TLR1/2 signaling may contribute to altered HSPC function in myelodysplastic syndrome by increasing local IL-1ß expression.

FGFR2 mutations are associated with poor outcomes in endometrioid endometrial cancer: An NRG Oncology/Gynecologic Oncology Group study.

PURPOSE: Activating FGFR2 mutations have been identified in ~10% of endometrioid endometrial cancers (ECs). We have previously reported that mutations in FGFR2 are associated with shorter disease free survival (DFS) in stage I/II EC patients. Here we sought to validate the prognostic importance of FGFR2 mutations in a large, multi-institutional patient cohort. METHODS: Tumors were collected as part of the GOG 210 clinical trial "Molecular Staging of Endometrial Cancer" where samples underwent rigorous pathological review and had more than three years of detailed clinical follow-up. DNA was extracted and four exons encompassing the FGFR2 mutation hotspots were amplified and sequenced. RESULTS: Mutations were identified in 144 of the 973 endometrioid ECs, of which 125 were classified as known activating mutations and were included in the statistical analyses. Consistent with FGFR2 having an association with more aggressive disease, FGFR2 mutations were more common in patients initially diagnosed with stage III/IV EC (29/170;17%) versus stage I/II EC (96/803; 12%; p=0.07, Chi-square test). Additionally, incidence of progression (progressed, recurred or died from disease) was significantly more prevalent (32/125, 26%) among patients with FGFR2 mutation versus wild type (120/848, 14%; p<0.001, Chi-square test). Using Cox regression analysis adjusting for known prognostic factors, patients with FGFR2 mutation had significantly (p<0.025) shorter progression-free survival (PFS; HR 1.903; 95% CI 1.177-3.076) and endometrial cancer specific survival (ECS; HR 2.013; 95% CI 1.096-3.696). CONCLUSION: In summary, our findings suggest that clinical trials testing the efficacy of FGFR inhibitors in the adjuvant setting to prevent recurrence and death are warranted.

Use of mutation profiles to refine the classification of endometrial carcinomas.

The classification of endometrial carcinomas is based on pathological assessment of tumour cell type; the different cell types (endometrioid, serous, carcinosarcoma, mixed, undifferentiated, and clear cell) are associated with distinct molecular alterations. This current classification system for high-grade subtypes, in particular the distinction between high-grade endometrioid (EEC-3) and serous carcinomas (ESC), is limited in its reproducibility and prognostic abilities. Therefore, a search for specific molecular classifiers to improve endometrial carcinoma subclassification is warranted. We performed target enrichment sequencing on 393 endometrial carcinomas from two large cohorts, sequencing exons from the following nine genes: ARID1A, PPP2R1A, PTEN, PIK3CA, KRAS, CTNNB1, TP53, BRAF, and PPP2R5C. Based on this gene panel, each endometrial carcinoma subtype shows a distinct mutation profile. EEC-3s have significantly different frequencies of PTEN and TP53 mutations when compared to low-grade endometrioid carcinomas. ESCs and EEC-3s are distinct subtypes with significantly different frequencies of mutations in PTEN, ARID1A, PPP2R1A, TP53, and CTNNB1. From the mutation profiles, we were able to identify subtype outliers, ie cases diagnosed morphologically as one subtype but with a mutation profile suggestive of a different subtype. Careful review of these diagnostically challenging cases suggested that the original morphological classification was incorrect in most instances. The molecular profile of carcinosarcomas suggests two distinct mutation profiles for these tumours: endometrioid-type (PTEN, PIK3CA, ARID1A, KRAS mutations) and serous-type (TP53 and PPP2R1A mutations). While this nine-gene panel does not allow for a purely molecularly based classification of endometrial carcinoma, it may prove useful as an adjunct to morphological classification and serve as an aid in the classification of problematic cases. If used in practice, it may lead to improved diagnostic reproducibility and may also serve to stratify patients for targeted therapeutics.

TLR7/8 agonist treatment induces an increase in bone marrow resident dendritic cells and hematopoietic progenitor expansion and mobilization.

There is accumulating evidence suggesting that toll-like receptor (TLR) signals play an important role in the regulation of hematopoietic stem/progenitor cells (HSPCs). TLR7/8 stimulation induces the myeloid differentiation of normal HSPCs and acute myeloid leukemia cells. However, the in vivo effect of TLR7/8 agonists on hematopoiesis is largely unknown. Here, we show that, similar to TLR4 and TLR2, treatment with the TLR7/8 agonist R848 induces an expansion of phenotypic hematopoietic stem cells (HSCs) with reduced repopulating potential and HSPC mobilization. In contrast to chronic TLR4 stimulation, treatment with R848 for 5 days did not induce a significant increase in myeloid-biased HSCs. Treatment with R848 results in a significant increase in classic dendritic cells (DCs) in the bone marrow, but a decrease in common dendritic cell progenitors and pre-DCs. Phenotypic analysis of DCs revealed that R848 treatment is associated with altered expression of certain chemokines, activation markers, and migratory receptors. Together, these data indicate that systemic administration of a TLR7/8 agonist has unique effects on hematopoiesis, including the expansion of DCs in the bone marrow, that might have clinical relevance to augment responses to certain immunotherapies, such as cancer vaccines and immune checkpoint blockade.

Clustering of Lynch syndrome malignancies with no evidence for a role of DNA mismatch repair.

OBJECTIVES: We ascertained a large kindred with an excess of Lynch syndrome-associated cancers. Our objective was to determine if a defect in one of the DNA mismatch repair (DMMR) genes was the probable cause of cancer susceptibility as microsatellite instability (MSI) and immunohistochemical (IHC) analysis of the probands' tumors did not provide a clear indication. METHODS: A detailed history and review of medical records was undertaken to construct a four-generation pedigree. Blood samples were obtained for analysis of germline DNA. Polymorphic repeats from the MLH1, MSH2, MSH6, and PMS2 loci were genotyped and the co-segregation of markers and disease was assessed. DMMR gene expression for all available tumors was evaluated by IHC. Combined bisulfite restriction analysis (COBRA) of MLH1 was utilized to test for germline epimutation. RESULTS: Four gynecologic carcinomas, 3 colon carcinomas, and 13 cases of adenomatous polyps were identified. The family met Amsterdam II criteria. The mean age of cancer diagnosis in the kindred was 63 years (range 44-82 years). DNA marker analyses excluded linkage to MLH1, MSH2, MSH6, and PMS2. Furthermore, MSI and IHC analysis of tumors did not suggest a role for DMMR. Methylation of the MLH1 promoter was identified in the peripheral blood leukocytes (PBLs) of a family member with an early onset colon cancer. CONCLUSIONS: We identified a large family with multiple Lynch malignancies and no evidence for an inherited defect in DMMR. This family represents an important but poorly understood form of autosomal dominant inherited cancer susceptibility. Aberrant MLH1 promoter methylation in normal tissues may be a marker for cancer susceptibility in families such as this.

Differential methylation hybridization array of endometrial cancers reveals two novel cancer-specific methylation markers.

PURPOSE: To identify novel endometrial cancer-specific methylation markers and to determine their association with clinicopathologic variables and survival outcomes. EXPERIMENTAL DESIGN: Differential methylation hybridization analysis (DMH) was done for 20 endometrioid endometrial cancers using normal endometrial DNA as a reference control. Combined bisulfite restriction analysis (COBRA) was used to verify methylation of sequences identified by DMH. Bisulfite sequencing was undertaken to further define CpG island methylation and to confirm the reliability of the COBRA. The methylation status of newly identified markers and the MLH1 promoter was evaluated by COBRA in a large series of endometrioid (n=361) and non-endometrioid uterine cancers (n=23). RESULTS: DMH and COBRA identified two CpG islands methylated in tumors but not in normal DNAs: SESN3 (PY2B4) and TITF1 (SC77F6/154). Bisulfite sequencing showed dense methylation of the CpG islands and confirmed the COBRA assays. SESN3 and TITF1 were methylated in 20% and 70% of endometrioid tumors, respectively. MLH1 methylation was seen in 28% of the tumors. TITF1 and SESN3 methylation was highly associated with MLH1 methylation (P<0.0001). SESN3 and TITF1 were methylated in endometrioid and non-endometrioid tumors, whereas MLH1 methylation was restricted to endometrioid tumors. Methylation at these markers was not associated with survival outcomes. CONCLUSIONS: The 5' CpG islands for SESN3 and TITF1 are novel cancer-specific methylation markers. Methylation at these loci is strongly associated with aberrant MLH1 methylation in endometrial cancers. SESN3, TITF1 and MLH1 methylation did not predict overall survival or disease-free survival in this large cohort of patients with endometrioid endometrial cancer.

Cellular stressors contribute to the expansion of hematopoietic clones of varying leukemic potential.

Hematopoietic clones harboring specific mutations may expand over time. However, it remains unclear how different cellular stressors influence this expansion. Here we characterize clonal hematopoiesis after two different cellular stressors: cytotoxic therapy and hematopoietic transplantation. Cytotoxic therapy results in the expansion of clones carrying mutations in DNA damage response genes, including TP53 and PPM1D. Analyses of sorted populations show that these clones are typically multilineage and myeloid-biased. Following autologous transplantation, most clones persist with stable chimerism. However, DNMT3A mutant clones often expand, while PPM1D mutant clones often decrease in size. To assess the leukemic potential of these expanded clones, we genotyped 134 t-AML/t-MDS samples. Mutations in non-TP53 DNA damage response genes are infrequent in t-AML/t-MDS despite several being commonly identified after cytotoxic therapy. These data suggest that different hematopoietic stressors promote the expansion of distinct long-lived clones, carrying specific mutations, whose leukemic potential depends partially on the mutations they harbor.

Osteoclasts are dispensable for hematopoietic progenitor mobilization by granulocyte colony-stimulating factor in mice.

The contribution of osteoclasts to hematopoietic stem/progenitor cell (HSPC) retention in the bone marrow is controversial. Studies of HSPC trafficking in osteoclast-deficient mice are limited by osteopetrosis. Here, we employed two non-osteopetrotic mouse models to assess the contribution of osteoclasts to basal and granulocyte colony-stimulating factor (G-CSF)-induced HSPC mobilization. We generated Rank(-/-) fetal liver chimeras using Csf3r(-/-) recipients to produce mice lacking G-CSF receptor expression in osteoclasts. Basal and G-CSF-induced HSPC mobilization was normal in these chimeras. We next acutely depleted osteoclasts in wild-type mice using the RANK ligand inhibitor osteoprotegerin. Marked suppression of osteoclasts was observed after a single injection of osteoprotegerin-Fc. Basal and G-CSF-induced HSPC mobilization in osteoprotegerin-Fc-treated mice was comparable to that in control mice. Together, these data indicate that osteoclasts are not required for the efficient retention of HSPCs in the bone marrow and are dispensable for HSPC mobilization by G-CSF.

MicroRNA-223 regulates granulopoiesis but is not required for HSC maintenance in mice.

MIR233 is genetically or epigenetically silenced in a subset of acute myeloid leukemia (AML). MIR223 is normally expressed throughout myeloid differentiation and highly expressed in hematopoietic stem cells (HSCs). However, the contribution of MIR223 loss to leukemic transformation and HSC function is largely unknown. Herein, we characterize HSC function and myeloid differentiation in Mir223 deficient mice. We show that Mir223 loss results in a modest expansion of myeloid progenitors, but is not sufficient to induce a myeloproliferative disorder. Loss of Mir223 had no discernible effect on HSC quiescence, long-term repopulating activity, or self-renewal capacity. These results suggest that MIR223 loss is likely not an initiating event in AML but may cooperate with other AML associated oncogenes to induce leukemogenesis.

Targeting bone marrow lymphoid niches in acute lymphoblastic leukemia.

In acute lymphoblastic leukemia (ALL) the bone marrow microenvironment provides growth and survival signals that may confer resistance to chemotherapy. Granulocyte colony-stimulating factor (G-CSF) potently inhibits lymphopoiesis by targeting stromal cells that comprise the lymphoid niche in the bone marrow. To determine whether lymphoid niche disruption by G-CSF sensitizes ALL cells to chemotherapy, we conducted a pilot study of G-CSF in combination with chemotherapy in patients with relapsed or refractory ALL. Thirteen patients were treated on study; three patients achieved a complete remission (CR/CRi) for an overall response rate of 23%. In the healthy volunteers, G-CSF treatment disrupted the lymphoid niche, as evidenced by reduced expression of CXCL12, interleukin-7, and osteocalcin. However, in most patients with relapsed/refractory ALL expression of these genes was markedly suppressed at baseline. Thus, although G-CSF treatment was associated with ALL cell mobilization into the blood, and increased apoptosis of bone marrow resident ALL cells, alterations in the bone marrow microenvironment were modest and highly variable. These data suggest that disruption of lymphoid niches by G-CSF to sensitize ALL cells to chemotherapy may be best accomplished in the consolidation where the bone marrow microenvironment is more likely to be normal.

Combined Microsatellite Instability, MLH1 Methylation Analysis, and Immunohistochemistry for Lynch Syndrome Screening in Endometrial Cancers From GOG210: An NRG Oncology and Gynecologic Oncology Group Study.

PURPOSE: The best screening practice for Lynch syndrome (LS) in endometrial cancer (EC) remains unknown. We sought to determine whether tumor microsatellite instability (MSI) typing along with immunohistochemistry (IHC) and MLH1 methylation analysis can help identify women with LS. PATIENTS AND METHODS: ECs from GOG210 patients were assessed for MSI, MLH1 methylation, and mismatch repair (MMR) protein expression. Each tumor was classified as having normal MMR, defective MMR associated with MLH1 methylation, or probable MMR mutation (ie, defective MMR but no methylation). Cancer family history and demographic and clinical features were compared for the three groups. Lynch mutation testing was performed for a subset of women. RESULTS: Analysis of 1,002 ECs suggested possible MMR mutation in 11.8% of tumors. The number of patients with a family history suggestive of LS was highest among women whose tumors were classified as probable MMR mutation (P = .001). Lynch mutations were identified in 41% of patient cases classified as probable mutation (21 of 51 tested). One of the MSH6 Lynch mutations was identified in a patient whose tumor had intact MSH6 expression. Age at diagnosis was younger for mutation carriers than noncarriers (54.3 v 62.3 years; P < .01), with five carriers diagnosed at age > 60 years. CONCLUSION: Combined MSI, methylation, and IHC analysis may prove useful in Lynch screening in EC. Twenty-four percent of mutation carriers presented with ECs at age > 60 years, and one carrier had an MSI-positive tumor with no IHC defect. Restricting Lynch testing to women diagnosed at age < 60 years or to women with IHC defects could result in missing a substantial fraction of genetic disease.

Uterine serous carcinoma: increased familial risk for lynch-associated malignancies.

Serous uterine cancer is not a feature of any known hereditary cancer syndrome. This study evaluated familial risk of cancers for patients with serous uterine carcinoma, focusing on Lynch syndrome malignancies. Fifty serous or mixed serous endometrial carcinoma cases were prospectively enrolled. Pedigrees were developed for 29 probands and tumors were assessed for DNA mismatch repair (MMR) abnormalities. Standardized incidence ratios for cancers in relatives were estimated. A second-stage analysis was undertaken using data from Gynecologic Oncology Group (GOG)-210. Incidence data for cancers reported in relatives of 348 patients with serous and mixed epithelial and 624 patients with endometrioid carcinoma were compared. Nineteen of 29 (65.5%) patients in the single-institution series reported a Lynch-related cancer in relatives. Endometrial and ovarian cancers were significantly overrepresented and a high number of probands (6 of 29, 20.7%) reported pancreatic cancers. None of the probands' tumors had DNA MMR abnormalities. There was no difference in endometrial or ovarian cancer incidence in relatives of serous and endometrioid cancer probands in the case-control study. Pancreatic cancers were, however, significantly more common in relatives of patients with serous cancer [OR, 2.39; 95% confidence interval (CI), 1.06-5.38]. We identified an excess of endometrial, ovarian, and pancreatic cancers in relatives of patients with serous cancer in a single-institution study. Follow-up studies suggest that only pancreatic cancers are overrepresented in relatives. DNA MMR defects in familial clustering of pancreatic and other Lynch-associated malignancies are unlikely. The excess of pancreatic cancers in relatives may reflect an as yet unidentified hereditary syndrome that includes uterine serous cancers.

DICER1 expression and outcomes in endometrioid endometrial adenocarcinoma.

BACKGROUND: The objective of this study was to determine whether lower expression levels of DICER1 are associated with disease recurrence in patients with endometrioid endometrial cancer. The authors also explored DNA methylation and haploinsufficiency as potential mechanisms related to altered DICER1 expression in these tumors. METHODS: DICER1 expression was assessed by quantitative polymerase chain reaction in a selected cohort of endometrioid endometrial tumors (N = 169). Loss of heterozygosity analyses were conducted using 2 single nucleotide polymorphisms, and combined bisulfate restriction analysis was used to assess methylation in the 5'-untranslated region of DICER1 in representative tumors. The correlations between DICER1 expression and clinicopathologic variables, including overall survival (OS) and disease-free survival (DFS), were assessed using nonparametric rank-sum tests and Cox proportional hazard models as appropriate. Survival distributions were described using the Kaplan-Meier method. A nested case-control analysis was conducted to confirm the association between transcript levels and disease recurrence. RESULTS: Lower DICER1 expression (hazard ratio [HR], 1.36; 95% confidence interval [CI], 1.05-1.75; P = .02) and advanced disease stage (HR, 2.79; 95%CI, 1.59-4.90; P < .001) were associated with worse DFS. Three variables were associated significantly with reduced OS: age (HR, 1.04; 95%CI, 1.02-1.06; P < .0001), advanced disease stage (HR, 6.41; 95%CI, 3.57-11.52; P < .0001), and high tumor grade (HR, 2.96; 95%CI, 1.46-5.99; P = .003). Nested case-control analyses confirmed that there were lower DICER1 transcript levels in patients who had recurrent disease (P = .01). Deletion of DICER1 sequences was an infrequent event (5% of analyzed patients), and no methylation was observed in the 5' DICER1 regulatory region. CONCLUSIONS: Lower DICER1 transcript levels were correlated with disease recurrence and worse DFS survival in patients with endometrioid endometrial cancer. The factors that influence DICER1 transcript levels in primary endometrial cancers remain unknown.

Differential Processing of {alpha}- and {beta}-Defensin Precursors by Matrix Metalloproteinase-7 (MMP-7).

Proteolytic processing of defensins is a critical mode of posttranslational regulation of peptide activity. Because mouse alpha-defensin precursors are cleaved and activated by matrix metalloproteinase-7 (MMP-7), we determined if additional defensin molecules, namely human neutrophil defensin pro-HNP-1 and beta-defensins, are targets for MMP-7. We found that MMP-7 cleaves within the pro-domain of the HNP-1 precursor, a reaction that does not generate the mature peptide but produces a 59-amino acid intermediate. This intermediate, which retains the carboxyl-terminal end of the pro-domain, had antimicrobial activity, indicating that the residues important for masking defensin activity reside in the amino terminus of this domain. Mature HNP-1 was resistant to processing by MMP-7 unless the peptide was reduced and alkylated, demonstrating that only the pro-domain of alpha-defensins is normally accessible for cleavage by this enzyme. From the 47-residue HBD-1 precursor, MMP-7 catalyzed removal of 6 amino acids from the amino terminus. Neither a 39-residue intermediate form of HBD-1 nor the mature 36-residue form of HBD-1 was cleaved by MMP-7. In addition, both pro-HBD-2, with its shorter amino-terminal extension, and pro-HBD-3 were resistant to MMP-7. However, human and mouse beta-defensin precursors that lack disulfide bonding contain a cryptic MMP-7-sensitive site within the mature peptide moiety. These findings support and extend accumulating evidence that the native three-dimensional structure of both alpha- and beta-defensins protects the mature peptides against proteolytic processing by MMP-7. We also conclude that sites for MMP-7 cleavage are more common at the amino termini of alpha-defensin rather than beta-defensin precursors, and that catalysis at these sites in alpha-defensin pro-domains results in acquisition of defensin activity.

ATR mutation in endometrioid endometrial cancer is associated with poor clinical outcomes.

PURPOSE Mutations in the DNA damage response gene ATR (exon 10 A10 mononucleotide repeat) have been previously described in endometrial and other cancers with defective DNA mismatch repair. In vitro studies showed that endometrial cancer cell lines with A10 repeat tract truncating mutations have a failure in the ATR-dependent DNA damage response. Cell lines carrying A10 mutations fail to trigger Chk1 activation in response to ionizing radiation and topoisomerase inhibitors. We sought to determine the frequency and clinicopathologic significance of ATR mutations in patients with endometrioid endometrial cancer. PATIENTS AND METHODS The ATR exon 10 A10 repeat was analyzed by direct sequencing in 141 tumors with microsatellite instability (MSI-positive) and 107 microsatellite stable (MSI-negative) tumors. The relationships between mutations and clinicopathologic variables, including overall and disease-free survival, were assessed using contingency table tests and Cox proportional hazard models. Results ATR mutations were identified in 12 cases (4.8%; three cases with insertions and nine cases with deletions). Mutations occurred exclusively in MSI-positive tumors (P = .02), with an overall mutation rate of 8.5%. Mutation was not associated with age, race, surgical stage, International Federation of Gynecology and Obstetrics grade, or adjuvant treatment. Multivariate analyses revealed a significant association with reduced overall survival (hazard ratio [HR] = 3.88; 95% CI, 1.64 to 9.18; P = .002) and disease-free survival (HR = 4.29; 95% CI, 1.48 to 12.45; P = .007). CONCLUSION Truncating ATR mutations in endometrial cancers are associated with biologic aggressiveness as evidenced by reduced disease-free and overall survival. Knowledge of ATR mutation status may hold promise for individualized treatment and targeted therapies in patients with endometrial cancer.

Epitope-positive truncating MLH1 mutation and loss of PMS2: implications for IHC-directed genetic testing for Lynch syndrome.

We assessed mismatch repair by immunohistochemistry (IHC) and microsatellite instability (MSI) analysis in an early onset endometrial cancer and a sister's colon cancer. We demonstrated high-level MSI and normal expression for MLH1, MSH2 and MSH6. PMS2 failed to stain in both tumors, strongly implicating a PMS2 defect. This family did not meet clinical criteria for Lynch syndrome. However, early onset endometrial cancers in the proband and her sister, a metachronous colorectal cancer in the sister as well as MSI in endometrial and colonic tumors suggested a heritable mismatch repair defect. PCR-based direct exonic sequencing and multiplex ligation-dependent probe amplification (MLPA) were undertaken to search for PMS2 mutations in the germline DNA from the proband and her sister. No mutation was identified in the PMS2 gene. However, PMS2 exons 3, 4, 13, 14, 15 were not evaluated by MLPA and as such, rearrangements involving those exons cannot be excluded. Clinical testing for MLH1 and MSH2 mutation revealed a germline deletion of MLH1 exons 14 and 15. This MLH1 germline deletion leads to an immunodetectable stable C-terminal truncated MLH1 protein which based on the IHC staining must abrogate PMS2 stabilization. To the best of our knowledge, loss of PMS2 in MLH1 truncating mutation carriers that express MLH1 in their tumors has not been previously reported. This family points to a potential limitation of IHC-directed gene testing for suspected Lynch syndrome and the need to consider comprehensive MLH1 testing for individuals whose tumors lack PMS2 but for whom PMS2 mutations are not identified.

Evidence for heritable predisposition to epigenetic silencing of MLH1.

Epigenetic silencing of MLH1 is the most common cause of defective DNA mismatch repair in endometrial and colorectal cancers. We hypothesized that variation in the MLH1 gene might contribute to the risk for MLH1 methylation and epigenetic silencing. We undertook a case-control study to test for the association between MLH1 variants and abnormal MLH1 methylation. Eight MLH1 SNPs were typed in the normal DNA from women with endometrial carcinoma. For these studies, the cases were women whose cancers exhibited MLH1 methylation (N = 98) and the controls were women whose cancers had no MLH1 methylation (N = 219). One MLH1 SNP, rs1800734, located in the MLH1 CpG island at -93 from the translation start site, was significantly associated with MLH1 methylation as were age at diagnosis and patient body mass index. In validation experiments, a similar-sized cohort of colorectal carcinoma patients (N = 387) showed a similar degree of association with the -93 SNP; a smaller cohort of endometrial carcinomas (N = 181) showed no association. Combining all 3 cohorts showed an odds ratio of 1.61 (95% CI: 1.20-2.16) for the AA or AG vs. GG genotype at the -93 SNP. Identification of risk alleles for MLH1 methylation could shed light on mechanisms of epigenetic silencing and may ultimately lead to new approaches to the prevention or treatment of malignancies associated with MLH1 inactivation.

Role of matrix metalloproteinase-7 in the modulation of a Chlamydia trachomatis infection.

To determine the role of matrix metalloproteinase-7 (MMP-7) in the pathogenesis of chlamydial infection, C57BL/6 wild-type (WT) and MMP-7 knockout (KO) mice were infected intravaginally with Chlamydia trachomatis mouse pneumonitis (MoPn). Over a period of 6 weeks postinfection, various organs were cultured for C. trachomatis. Other infected animals were mated to assess their fertility status. No significant differences were observed between WT and KO mice in the number of animals with positive vaginal cultures, length of time of C. trachomatis shedding, or the number of C. trachomatis inclusion-forming units (IFU) recovered from their genital tracts. Likewise, the number of animals with hydrosalpinx, and the fertility rates and the number of embryos per mouse, were similar in WT and KO mice. Cultures from the spleen, lungs, kidneys and large intestine yielded similar numbers of IFU from WT and KO mice. However, the number of C. trachomatis IFU recovered from the small intestine of KO mice was significantly higher than that recovered from the small intestine of WT mice at 2 weeks postinfection. Because MMP-7 KO mice are deficient in active intestinal alpha-defensins, the results suggest that these components play a role in regulating colonization of the gastrointestinal tract by Chlamydia. By contrast, MMP-7 is dispensable in the progression and resolution of the genital tract infection.