Estrogen up-regulates mismatch repair activity in normal and malignant endometrial glandular cells

Sex steroid hormones and DNA repair regulation: Implications on cancer treatment responses

The role of sex steroid hormones (SSHs) has been shown to modulate cancer cytotoxic treatment sensitivity. Dysregulation of DNA repair associated with genomic instability, abnormal cell survival and not only promotes cancer progression but also resistance to cancer treatment. The three major SSHs, androgen, estrogen, and progesterone, have been shown to interact with several essential DNA repair components. The presence of androgens directly regulates key molecules in DNA double-strand break (DSB) repair. Estrogen can promote cell proliferation and DNA repair, allowing cancer cells to tolerate chemotherapy and radiotherapy. Information on the role of progesterone in DNA repair is limited: progesterone interaction with some DNA repair components has been identified, but the biological significance is still unknown. Here, we review the roles of how each SSH affects DNA repair regulation and modulates response to genotoxic therapies and discuss future research that can be beneficial when combining SSHs with cancer therapy. We also provide preliminary analysis from publicly available databases defining the link between progesterone/PR and DDRs & DNA repair regulation that plausibly contribute to chemotherapy response and breast cancer patient survival.

Association of MLH1-93G>A polymorphisms toward lung cancer susceptibility and its association with clinical outcome in North Indian patients treated with platinum-based chemotherapy

Background

Lung cancer is one of the most prevalent and main causes of malignancy-related deaths worldwide, especially in developed countries. Epidemiological studies have demonstrated that individuals having alterations in a particular gene may have a high risk of developing certain types of cancer.

Materials and Methods

In the present study, 500 Indian lung cancer patients and 500 healthy controls were enrolled. Polymerase chain reaction-restriction fragment length polymorphism method was used to identify the genotype of enrolled individuals and MedCalc statistical package was used for carrying out statistical analysis.

Results

In this study, we found a reduced risk of developing adenocarcinoma in patients harboring variant (P = 0.0007) and combined type genotype (P = 0.008), whereas an increased risk for small-cell lung carcinoma (SCLC) development for those subject harboring GA genotypes (P = 0.03) was also observed. Further, heterozygous type and combined type genotype of heavy smokers for MLH1 polymorphism reported a 2-fold (P = 0.001) and 1.8-fold increased risk toward lung cancer development, respectively (P = 0.007). In case of females, the subjects harboring a variant allele have a significantly reduced risk for lung cancer development (P = 0.0001). For MLH1 polymorphism, reduced risk of developing tumor to T3 or T4 stage was observed (P = 0.04). Moreover, this is the first study reporting overall survival (OS) association for north Indian lung cancer patients with platinum-based doublet chemotherapy; for docetaxel, a three-fold increase in hazard ratio and corresponding low median standard survival time (8.4 months) for mutant and combined type genotype (P = 0.04) was observed.

Conclusions

These results suggest that MLH1-93G>A polymorphism is involved in modulating the risk toward lung cancer. Our study also concluded a negative association of OS in patients undergoing carboplatin/cisplatin and docetaxel chemotherapy.

Endometrial cancer in Lynch syndrome

Lynch syndrome (LS) is an autosomal dominant inherited disease caused by germline pathogenic variants (PVs) in mismatch repair (MMR) genes. LS-associated endometrial cancer (LS-EC) is the most common extraintestinal sentinel cancer caused by germline PVs in MMR genes, including MLH1, MSH2, MSH6 and PMS2. The clinicopathologic features of LS-EC include early age of onset, lower body mass index (BMI), endometrioid carcinoma and lower uterine segment involvement. There has been significant progress in screening, diagnosis, surveillance, prevention and treatment of LS-EC. Many studies support universal screening for LS among patients with EC. Screening mainly involves a combination of traditional clinical criteria and molecular techniques, including MMR-immunohistochemistry (MMR-IHC), microsatellite instability (MSI) testing, MLH1 promoter methylation testing and gene sequencing. The effectiveness of endometrial biopsy and transvaginal ultrasound (TVS) for clinical monitoring of asymptomatic women with LS are uncertain yet. Preventive strategies include hysterectomy and bilateral salpingo-oophorectomy (BSO) as well as chemoprophylaxis using exogenous progestin or aspirin. Recent research has revealed the benefits of immunotherapy for LS-EC. The NCCN guidelines recommend pembrolizumab and nivolumab for treating patients with advanced or recurrent microsatellite instability-high (MSI-H)/mismatch repair-deficient (dMMR) EC.

Gynecological Cancers Caused by Deficient Mismatch Repair and Microsatellite Instability

Mutations in mismatch repair genes leading to mismatch repair (MMR) deficiency (dMMR) and microsatellite instability (MSI) have been implicated in multiple types of gynecologic malignancies. Endometrial carcinoma represents the largest group, with approximately 30% of these cancers caused by dMMR/MSI. Thus, testing for dMMR is now routine for endometrial cancer. Somatic mutations leading to dMMR account for approximately 90% of these cancers. However, in 5-10% of cases, MMR protein deficiency is due to a germline mutation in the mismatch repair genes MLH1, MSH2, MSH6, PMS2, or EPCAM. These germline mutations, known as Lynch syndrome, are associated with an increased risk of both endometrial and ovarian cancer, in addition to colorectal, gastric, urinary tract, and brain malignancies. So far, gynecological cancers with dMMR/MSI are not well characterized and markers for detection of MSI in gynecological cancers are not well defined. In addition, currently advanced endometrial cancers have a poor prognosis and are treated without regard to MSI status. Elucidation of the mechanism causing dMMR/MSI gynecological cancers would aid in diagnosis and therapeutic intervention. Recently, a new immunotherapy was approved for the treatment of solid tumors with MSI that have recurred or progressed after failing traditional treatment strategies. In this review, we summarize the MMR defects and MSI observed in gynecological cancers, their prognostic value, and advances in therapeutic strategies to treat these cancers.

Two-sided role of estrogen on endometrial carcinogenesis: stimulator or suppressor?

Endometrial carcinoma (EC) often expresses estrogen receptors (ER), and the growth of EC is stimulated by estrogen. Therefore, EC is considered to be an estrogen-dependent tumor. However, the role of estrogen in endometrial carcinogenesis is somewhat unclear because the majority of EC occurs at peri- or post menopause when serum estrogen levels are generally decreased. In this article, we describe the double-edged role of estrogen in the genesis of EC, especially in terms of mismatch repair functions in vitro and in vivo, i.e. when serum estradiol (E2) levels are relatively low (approximately less than 90 pg/ml), and E2 enhance the carcinogenesis, whereas high E2 levels may suppress the carcinogenesis. This will deepen mechanistic insight into unopposed estrogen.

4-hydroxy estrogen induces DNA damage on codon 130/131 of PTEN in endometrial carcinoma cells

Catechol estrogens, such as 4-hydroxyestradiol (4-OHE2), are estrogen metabolites that form DNA adducts and may induce mutations and subsequent cell transformation in mammary cells; however, little is known about their roles in endometrial carcinogenesis. Furthermore, it remains unclear whether 4-OHE2 is able to induce DNA damage on specific genes involved in carcinogenesis or a 'pro'-mutation status such as microsatellite instability (MSI). Therefore, we modified terminal transferase-dependent PCR by the application of a capillary sequencer to detect DNA damage at the single base level. Using this method, we demonstrated that 4-OHE2 directly induced DNA damage on codon 130/131 in exon 5 of PTEN, which is a mutation hot spot for PTEN in endometrial carcinoma. Whereas, both estradiol and 4-OHE2 treatment did not affect MSI status in immortalized endometrial glandular cells. 4-OHE2 might contribute to endometrial carcinogenesis by inducing PTEN mutation on codon 130/131.

Gender and cell-type-specific effects of the transcription-coupled repair protein, ERCC6/CSB, on repeat expansion in a mouse model of the fragile X-related disorders

The repeat expansion diseases are human genetic disorders that arise from the expansion of a tandem-repeat tract. The Fragile X-related disorders are members of this disease group in which the repeat unit is CGG/CCG and is located in the 5′ untranslated region of the FMR1 gene. Affected individuals often show mosaicism with respect to repeat number resulting from both expansion and contraction of the repeat tract; however, the mechanism responsible for these changes in repeat number is unknown. The work from a variety of model systems suggests that transcription-coupled repair (TCR) may contribute to repeat instability in diseases resulting from CAG/CTG-repeat expansion. To test whether TCR could contribute to repeat instability in the Fragile X-related disorders, we tested the effect of mutations in Csb (Cockayne syndrome group B), a gene essential for TCR, in a knock-in mouse model of these disorders. We found that the loss of CSB affects expansions in a gender and cell-type-specific manner. Our data also show an unanticipated gender difference in instability even in Csb+/+ animals that may have implications for our understanding of the mechanism of repeat expansion in the FX mouse model and perhaps for humans as well.

Endometrial Carcinoma in Women Aged 40 Years and Younger

Context.—Endometrial carcinoma is a disease of older postmenopausal women, and is relatively uncommon in patients younger than 40 years. Endometrial carcinomas in this age group may be familial, associated with Lynch syndrome, or sporadic.

Objectives.—To present our current knowledge of endometrial carcinomas in women younger than 40 years.

Data Sources.—The review is based on previously published articles on this topic.

Conclusions.—Most endometrial carcinomas that occur in this age group are associated with estrogen excess. They are usually low-grade endometrioid carcinomas that present at low stages and are associated with favorable clinical outcomes. Tumors associated with mismatch repair abnormalities and Lynch syndrome appear to be distinct, with worse prognostic factors and, possibly, clinical behavior. Conservative hormonal therapy and ovarian conservation are reasonable considerations in the management of these young patients, but carry the risk of tumor progression, recurrence, and an occult synchronous or metachronous ovarian carcinoma.

Mismatch repair protein expression in 1049 endometrial carcinomas, associations with body mass index, and other clinicopathologic variables

OBJECTIVE

Links between obesity, with its attendant estrogen abnormalities, and the endometrial carcinoma (EC) DNA Mismatch Repair Protein (MMR) system have recently been proposed. We investigated relationships between body mass index (BMI) and clinicopathological correlates including MMR expression in a large single institution EC cohort.

METHODS

Clinical and pathological databases from 2007 to 2012 were used to identify consecutive hysterectomy specimens with EC. Univariate and multivariate analyses were used to explore relationships between BMI, age, stage, tumor type and immunohistochemical results for MLH1, PMS2, MSH2 and MSH6.

RESULTS

1049 EC were identified. Overall, BMI was higher amongst women with normal MMR (p=0.002). However, when stratified by age and specific MMR, statistically significant differences localized exclusively to women <50years old with loss of MSH2 and/or MSH6 (p=0.003 and p=0.005 respectively). Higher BMI correlated with endometrioid FIGO 1 and 2 tumors (p<0.001) and with stage 1a (p<0.001). Conversely, MMR abnormalities did not show significant associations with stage (p=0.302) or histologic grade (p=0.097).

CONCLUSIONS

BMI showed statistically significant associations with MMR expression, tumor grade and stage amongst 1049 consecutive EC. Obesity correlates with lower grade and stage EC. A link between BMI and maintenance of the MMR system is not supported by our data because the only statistically significant association occurred in women <50years old with MSH2 and/or MSH6 abnormalities where Lynch syndrome related cases are expected to cluster.

Mismatch repair gene polymorphisms and association with lung cancer development

hMLH1 and hMSH2 are two of the main members of the mismatch repair (MMR) genes family. Polymorphism of MMR genes is associated with a risk of developing sporadic and hereditary tumors. In the present case-control study, we investigated the promoter polymorphisms of selected mismatch repair genes: hMLH1 (rs1800734) and hMSH2 (rs2303425), and the risk they present regarding the development of lung cancer in the Slovak population. The study included 422 lung cancer cases, 511 controls for hMLH1 gene and 486 controls for hMSH2 gene. Polymorphism was investigated by a PCR-RFLP method. The risk of cancer development was evaluated in both dominant and recessive genetic models. The evaluation of rs1800734 polymorphism in patients in the dominant model showed a significantly decreased risk of lung cancer in the presence of at least one variant allele A (genotype GA and AA) (OR=1.40; 95% CI=1.08-1.82; p=0.01). These findings were equally strong expressed in women (OR=2.00; 95% CI=1.23-3.25; p=0.006). The results for rs2303425 polymorphism revealed an increased risk of lung cancer for variant genotype CC (OR=2.28; 95% CI=1.12-4.63; p=0.024) in the recessive model. A combination of rs1800734 and rs2303425 polymorphisms was shown to be risky for genotype GGCC; OR=3.08; 95% CI=1.09-8.72; p=0.03. The risk appeared even greater in female gender; (OR=11.56; 95% CI=1.33-100.36, 1.26-94.66; p=0.005. We conclude that the genotype of mismatch repair genes underscores the risk of lung cancer development in the Slovak population.

The mismatch repair protein MSH2 is rate limiting for repeat expansion in a fragile X premutation mouse model

Fragile X-associated tremor and ataxia syndrome, Fragile X-associated primary ovarian insufficiency, and Fragile X syndrome are Repeat Expansion Diseases caused by expansion of a CGG•CCG-repeat microsatellite in the 5 UTR of the FMR1 gene. To help understand the expansion mechanism responsible for these disorders, we have crossed mice containing∼147 CGG•CCG repeats in the endogenous murine Fmr1 gene with mice containing a null mutation in the gene encoding the mismatch repair protein MSH2. MSH2 mutations are associated with elevated levels of generalized microsatellite instability. However, we show here for the first time that in the FX mouse model, all maternally and paternally transmitted expansions require Msh2. Even the loss of one Msh2 allele reduced the intergenerational expansion frequency significantly. Msh2 is also required for all somatic expansions and loss of even one functional Msh2 allele reduced the extent of somatic expansion in some organs. Tissues with lower levels of MSH2 were more sensitive to the loss of a single Msh2 allele. This suggests that MSH2 is rate limiting for expansion in this mouse model and that MSH2 levels may be a key factor that accounts for tissue-specific differences in expansion risk.

Mismatch repair proteins in recurrent prostate cancer

Normal cell function requires strict control over the repair of DNA damage, which prevents excessive mutagenesis. An enhanced accumulation of mutations results in the multistep process generally known as carcinogenesis. Defects in repair pathways fuel such mutagenesis by allowing reiterative cycles of mutation, selection, and clonal expansion that drive cancer progression. The repair of mismatches is an important mechanism in the prevention of such genetic instability. In addition, proteins of this pathway have the unique ability to function in DNA damage response by inducing apoptosis when irreparable damage is encountered. Though originally identified primarily in association with a predisposition to hereditary colon cancer, mismatch repair defects have been identified in many other cancer types, including prostate cancer. From the first discovery of microsatellite instability in prostate cancer cell lines and tumor samples, variations in protein levels and a possible association with recurrence and aggression of disease have been described. Current results suggest that the involvement of mismatch repair proteins in prostate cancer may differ from that found in colorectal cancer, in the type of proteins and protein defects involved and the type of causative mutations. Additional work is clearly needed to investigate this involvement and the possibility that such defects may affect treatment response and androgen independence.

Involvement of pelvic inflammation-related mismatch repair abnormalities and microsatellite instability in the malignant transformation of ovarian endometriosis

Inflammation in the ovary, including ovulation and pelvic inflammatory disease, has been proposed to play a role in the pathogenesis of ovarian cancer. Endometriotic lesions trigger a local inflammatory reaction and have been reported to be associated with an increased risk of epithelial ovarian cancer. However, the precise molecular mechanisms of ovarian cancer arising from endometriosis are still to be elucidated. To clarify the involvement of mismatch repair (MMR) abnormalities in the inflammation-associated malignant transformation of endometriosis, the immunohistochemical expression of mismatch repair proteins (human mutL homolog 1 [hMLH1] and human mutS homolog 2 [hMSH2]) was examined in 27 cases of ovarian endometriosis, 25 cases of ovarian carcinoma accompanied by endometriosis, and 39 cases of solitary ovarian carcinoma. In addition, the relationship between mismatch repair abnormalities including the microsatellite instability, PTEN (phosphatase and tensin homolog) mutation, and clinicopathologic parameters was analyzed. The expression of mismatch repair proteins was stepwisely decreased in endometriosis, ovarian carcinoma accompanied by endometriosis, and ovarian carcinoma. Tumors harboring multiple microsatellite instability (high-frequency microsatellite instability [MSI-H]) were detected in 4 (14.8%) of 27 cases of endometriosis and 7 (30.4%) of 23 cases of ovarian carcinomas. The frequency of PTEN mutations was higher in MSI-H cases than in microsatellite instability-stable (MSI-S) cases. In 2 cases of ovarian carcinoma accompanied by endometriosis, the decreased expression of mismatch repair proteins and MSI-H was observed in both the endometriosis and carcinoma lesions. Clinicopathologically, the MSI-H cases were associated with elevated serum levels of C-reactive protein and higher white blood cell counts. These findings suggest that mismatch repair abnormalities might be involved in the malignant transformation of ovarian endometriosis and that inflammation induces mismatch repair abnormalities during ovarian carcinogenesis arising from endometriosis.

Tumor spectrum in lynch syndrome, DNA mismatch repair system and endogenous carcinogens

Inactivation of Mismatch Repair genes in Lynch Syndrome, caused by inherited mutations, decreases the ability to repair DNA errors throughout life. This deficit may allow the development of any tumor type. Nevertheless, the Syndrome develops a specific tumor spectrum associated with the disease. We think that such spectrum of tumors would be related to the action of certain endogenous carcinogens such as bile acids and estrogens that aggravate the inherited defect.

Estrogen stimulates the expression of mismatch repair gene hMLH1 in colonic epithelial cells

Estrogen is reported to have a protective effect on colon cancer; however, the underlying mechanism is unclear. Impaired mismatch repair plays an important role in colonic carcinogenesis. The purpose of this study was to investigate the association of estrogen on regulating mismatch repair expression in colonic epithelial cells. In cultured COLO205 cells, the effect of estradiol (E2) and antagonist ICI182.780 on the expression of hMLH1 and hMSH2 was studied using reverse transcription-PCR and Western blotting. The correlation between serum level E2 and the expression of hMLH1 and hMSH2 in colonic mucosal tissue of 42 healthy individuals was also examined using reverse transcription-PCR and immunohistochemical staining. E2 increased the expression of hMLH1 in COLO205 cells, which was suppressed by ICI182.780. However, the effect of E2 on hMSH2 expression was not significant in COLO205 cells. In healthy individuals, a strong positive correlation of E2 level with hMLH1 expression in normal colonic epithelial cell was observed when serum E2 level was >45 pg/mL, but no correlation was seen between E2 and hMSH2 expression. E2 affects the expression of hMLH1 but not hMSH2 in vitro, and high serum E2 level correlates with hMLH1 expression in vivo. These findings suggest that the anticolonic cancer effect of estrogen may be related to hMLH1 regulation.

DNA mismatch repair and the transition to hormone independence in breast and prostate cancer

The molecular basis for the progression of breast and prostate cancer from hormone dependent to hormone independent disease remains a critical issue in the management of these two cancers. The DNA mismatch repair system is integral to the maintenance of genomic stability and suppression of tumorigenesis. No firm consensus exists regarding the implications of mismatch repair (MMR) deficiencies in the development of breast or prostate cancer. However, recent studies have reported an association between mismatch repair deficiency and loss of specific hormone receptors, inferring a potential role for mismatch repair deficiency in this transition. An updated review of the experimental data supporting or contradicting the involvement of MMR defects in the development and progression of breast and prostate cancer will be provided with particular emphasis on their implications in the transition to hormone independence.

Clinicopathological features in endometrial carcinoma associated with Lynch syndrome in China

OBJECTIVE

To study the clinicopathological characteristics of Lynch syndrome-associated endometrial carcinoma in China.

METHODS

Twenty-seven patients who fulfilled Amsterdam criteria II were classified as having Lynch syndrome-associated endometrial carcinoma (group A), and 331 patients without a family history of cancer were classified as having sporadic endometrial carcinoma (group B).

RESULTS

There were 81 malignancies in 27 families with Lynch syndrome-associated endometrial carcinoma, including colorectal cancer (24.7%), endometrial carcinoma (21.0%), and liver (12.3%), stomach (9.9%), lung (6.2%), and breast (6.2%) cancers. Mean age at the time of diagnosis was 49.7 years in group A and 56.3 years in group B (P = 0.004). Second primary cancers occurred in 33.3% of patients in group A and 5.1% in group B (P = 0.000). The most common second primary cancers were colorectal cancer (44%) and ovarian cancer (22%). The percentage of obese patients was higher in group A (P= 0.013). There was no difference between the 2 groups in incidence of diabetes mellitus or hypertension or in histological type and International Federation of Gynecology and Obstetrics stage. The 5-year survival rates for groups A and B were 96.2% and 79.6%, respectively. Prognosis for group A was better than for group B (P = 0.045).

CONCLUSIONS

Some clinicopathological features of Lynch syndrome-associated endometrial carcinoma, such as early onset and multiple primary carcinomas are similar in the Chinese and American/European populations. However, the Chinese population had a unique family cancer distribution that included lung and breast cancers. Well-differentiated grade and good prognosis imply better biobehavior of Lynch syndrome-associated endometrial carcinoma in the Chinese population.

Estrogens, MSI and Lynch syndrome-associated tumors

Estrogens play a major role in the biology of hormone-responsive tissues but also in the normal physiology of various non-typical hormone-responsive tissues. In disease, estrogens have been associated with tumor development, in particular with tumors such as breast, endometrium, ovary and prostate. In this paper we will review the molecular mechanisms by which estrogens are involved in cancer development, with a special focus in Lynch syndrome related neoplasia. Further, we discuss the role estrogens might have on cell proliferation and apoptosis, how estrogens metabolites can induce DNA damage and we discuss a possible connection between estrogens and changes in DNA (hypo- and hyper) methylation. In this review we will also address the protective effect that high levels of estrogens have in MMR related neoplasias.

MSH2 118T>C and MSH6 159C>T promoter polymorphisms and the risk of colorectal cancer

The most important indicator of colorectal cancer (CRC) risk is the presence of family history of the disease. Inherited genetic changes, such as single nucleotide polymorphisms, in key candidate genes may contribute to CRC risk. We investigated whether promoter polymorphisms in DNA mismatch repair (MMR) genes MSH2 and MSH6 are associated with the risk of CRC. We genotyped 929 CRC patients and 1098 control subjects from Ontario, and 467 patients and 344 controls from Newfoundland and Labrador, for two promoter polymorphisms in the MMR genes MSH2 and MSH6 using the fluorogenic 5' nuclease assay. We used unconditional logistic regression to evaluate the association between each polymorphism and CRC after adjusting for age and sex. The associations between polymorphisms and tumor clinicopathological features were evaluated with a Pearson's chi-squared test or Fisher's exact test. All statistical tests were two sided. We observed strong associations between the MSH2 -118T>C polymorphism and family history of CRC based on the Amsterdam criteria I (P = 0.005) and Amsterdam criteria I and II (P = 0.036) among cases from Ontario. This association was especially evident among female CRC patients in Ontario (for Amsterdam criteria I, and I and II combined, P = 0.003 and P = 0.0001, respectively). The MSH2 -118T>C polymorphism was associated with strong family history of CRC in Ontario patients.

Early genetic instability of both epithelial and stromal cells in esophageal squamous cell carcinomas, contrasted with Barrett's adenocarcinomas

BACKGROUND

We have shown previously that stromal genetic alteration may make a greater contribution to early genesis of ulcerative colitis-associated tumors than sporadic colon cancers. We assessed whether similar differences in genetic alteration might exist between squamous cell carcinomas (SCCs) and Barrett's adenocarcinomas (BACs) of the esophagus.

METHODS

We investigated epithelial and stromal genetic instability with five National Cancer Institute standard (NCI), four chromosome 17 (Chr. 17), and six tumor suppressor gene (TSG) microsatellite markers in 26 SCC and 12 BAC cases and in 11 normal controls, using a novel combination of microdissection, polymerase chain reaction, and GeneScan.

RESULTS

Frequency of epithelial loss of heterozygosity (LOH) increased in the order background mucosa, to precursor lesions, to tumors with both types of carcinoma, especially for the Chr. 17 and TSG markers, while stromal LOH was relatively high but consistent from background mucosa to carcinoma. Epithelial LOH of D17S796 demonstrated a significantly higher frequency in SCCs than in BACs, without significant variation in p53 overexpression. The frequency of microsatellite instability (MSI) showed constant high levels in both epithelium and stroma of background, dysplasia, and carcinomas in the SCC series, and rather low frequencies in the BAC series. Although epithelial hMLH1 and hMSH2 expression decreased with tumor progression, no correlation was found with the individual MSI status.

CONCLUSIONS

Although epithelial LOH exists similarly in both lesion types, whereas epithelial and stromal MSI may occur in a relatively early phase of SCC development, stromal MSI is rare in BACs, strongly suggesting differences in tumorigenesis between the two types.