K-ras mutation in tamoxifen-related endometrial polyps

Mucinous Proliferations of the Uterine Corpus: Comprehensive Appraisal of an Evolving Spectrum of Neoplasms

A variety of endometrial lesions may contain mucinous cells. Herein, the author reviews the literature on the classification and clinicopathologic significance of uterine corpus proliferations with a significant mucinous component, assesses the 2020 World Health Organization classification of such lesions, and presents a diagnostic framework. The key epithelial mucinous lesions include mucinous metaplasia, atypical mucinous glandular proliferation and mucinous carcinoma. Each of these categories are classifiable into "usual" and gastrointestinal subtypes, the latter being indicative of intestinal (presence of goblet cells) and/or gastric-type (abundant, pale eosinophilic or clear cytoplasm and well-defined cell borders) morphology. It has been proposed that at least focal expression of gastrointestinal immunohistochemical markers be required for all gastrointestinal type lesions, and for gastrointestinal type atypical mucinous glandular proliferation and carcinoma, minimality or absence of estrogen receptor expression, and the absence of an endometrioid component. Mucinous carcinomas of the usual type, in which >50% of the tumor is comprised of a mucinous component, are the most common. Morphologic subtypes include mucinous carcinoma with microglandular features and mucinous carcinoma with signet rings (signet ring carcinoma). Endometrioid carcinomas with a less than a 50% mucinous component are classified as endometrioid carcinoma with mucinous differentiation. Several studies have directly compared endometrioid and mucinous carcinomas, the latter presumably of the usual type, with respect to patient outcomes after treatment. All have found no difference in overall and disease free survival between these groups. However, three major studies have found mucinous carcinomas to be associated with a higher risk of lymph node metastases. Nineteen cases of mucinous carcinoma of the gastrointestinal type have been reported, and the limited data on their follow-up after primary treatment suggests that this subtype is more clinically aggressive and should accordingly be classified separately from mucinous carcinomas of the usual type. The morphologic spectrum of mucinous carcinoma of the gastrointestinal type is unclear and continues to evolve. Mucinous change, which may sometimes be extensive, may also be associated with papillary proliferation of the endometrium, adenomyoma of the endocervical type, atypical, and typical adenomyomas. In a curettage or biopsy, intestinal type mucinous epithelium may be indicative of any of the gastrointestinal lesions mentioned above, but may also represent samplings of uterine teratomas, yolk sac tumors, genital and extragenital adenocarcinomas with intestinal differentiation, or low-grade appendiceal mucinous neoplasms that secondarily involve the endometrium.

Atypical uterine polyps show morphologic and molecular overlap with mullerian adenosarcoma but follow a benign clinical course

A subset of clinically benign uterine polyps shows atypical morphologic features worrisome for, but not diagnostic of, Mullerian adenosarcoma. We report clinicopathologic data for 63 polyps from 58 women with atypical morphologic features including abnormal architecture, abnormal periglandular stroma, stromal atypia, and mitoses >2 per 10 hpf. Four (11%) of 36 women with follow-up tissue sampling had residual/recurrent atypical polyp. Twelve (27%) of 44 women underwent hysterectomy subsequent to a diagnosis of atypical polyp. No patient developed adenosarcoma over median follow-up of 150 months. Twenty-one primary atypical polyps underwent molecular profiling. Five (24%) harbored chr 12q13-15 gain or amplification, 9/20 (45%) harbored chr 6q25.1 gain, and 7/21 (33%) had no significant copy number alterations. Gains of chr 1q, chr 8p12, and chr 10q11.21-23, amplifications of chr 12q24.12-13, chr 15p24.1-26.1, and chr 18q21.33, and loss of chr 7 and chr 11q21 were each seen in a single polyp. Mean tumor mutational burden was 3.1 (range, 0.76-8.365) mutations/Mb. Pathogenic point mutations were identified in 12/20 (60%) primary atypical polyps. We propose the term "atypical uterine polyps" for these lesions, which show biologic overlap with early Mullerian adenosarcoma but lack molecular alterations characteristic of clinically aggressive adenosarcoma and appear to follow a benign clinical course. Conservative management with close clinical follow-up and repeat sampling can be considered for these lesions, when clinically appropriate.

The Potential Role of Nutraceuticals as an Adjuvant in Breast Cancer Patients to Prevent Hair Loss Induced by Endocrine Therapy

Nutraceuticals, natural dietary and botanical supplements offering health benefits, provide a basis for complementary and alternative medicine (CAM). Use of CAM by healthy individuals and patients with medical conditions is rapidly increasing. For the majority of breast cancer patients, treatment plans involve 5–10 yrs of endocrine therapy, but hair loss/thinning is a common side effect. Many women consider this significant, severely impacting on quality of life, even leading to non-compliance of therapy. Therefore, nutraceuticals that stimulate/maintain hair growth can be proposed. Although nutraceuticals are often available without prescription and taken at the discretion of patients, physicians can be reluctant to recommend them, even as adjuvants, since potential interactions with endocrine therapy have not been fully elucidated. It is, therefore, important to understand the modus operandi of ingredients to be confident that their use will not interfere/interact with therapy. The aim is to improve clinical/healthcare outcomes by combining specific nutraceuticals with conventional care whilst avoiding detrimental interactions. This review presents the current understanding of nutraceuticals beneficial to hair wellness and outcomes concerning efficacy/safety in breast cancer patients. We will focus on describing endocrine therapy and the role of estrogens in cancer and hair growth before evaluating the effects of natural ingredients on breast cancer and hair growth.

Endometrial polyps: Pathogenesis, sequelae and treatment

Endometrial polyps are overgrowths of endometrial glands that typically protrude into the uterine cavity. Endometrial polyps are benign in nature and affect both reproductive age and postmenopausal women. Although endometrial polyps are relatively common and may be accompanied by abnormally heavy bleeding at menstruation. In asymptomatic women, endometrial polyps may regress spontaneously, in symptomatic women endometrial polyps can be treated safely and efficiently with hysteroscopic excision.

Clinical Significance of Positive Pelvic Washings in Uterine Papillary Serous Carcinoma Confined to an Endometrial Polyp

Uterine papillary serous carcinoma (UPSC) represents 10% of endometrial carcinomas. Significant number of patients initially present with extrauterine disease. The role of adjuvant treatment in low stage, especially polyp-confined UPSC is controversial. This multi-institutional study evaluated the significance of positive pelvic washing (PW) and adjuvant treatment on disease recurrence in a setting of endometrial polyp-confined UPSC. Surgical pathology files from 3 institutions were searched for cases of endometrial polyp-confined UPSC. Following histologic review, cases were clinically staged as Stage I, without myoinvasion or lymphovascular invasion. Clinicopathologic characteristics, results of PW, and type of adjuvant therapy were recorded. Statistical analysis using the Kaplan-Meier method for survival and Fisher exact test were performed. Thirty-three patients were included in the study. All patients were diagnosed with polyp-confined UPSC. The size of the polyp ranged from 0.3 to 4.3 cm. PW was positive for tumor cells in 8/33 (24%) patients. Twenty-two patients (66.6%) received some type of adjuvant treatment. Six patients (18%) developed recurrent disease. There was no significant difference in disease-free survival in the patients receiving adjuvant treatment versus not (P=0.375). However, there was significant association (P=0.0013) between positive PW and disease recurrence. Data are conflicting whether positive PW affects prognosis in low-stage endometrial carcinomas. Our study showed that in UPSC, malignant cells can be present in PW without lymphovascular invasion or myoinvasion and may have negative prognostic implication. Our data also reflect the controversies in the role of adjuvant treatment in endometrium-confined UPSC.

The significance of markers in the diagnosis of endometrial cancer

Endometrial cancer is one of the most common cancers experienced by women throughout the world. It is also the most common malignancy within the female reproductive system, representing 37.7% of all disorders. The incidence increases with age, and is diagnosed most frequently in women between 45 and 65 years old. In the last few years, numerous studies have been performed to identify tumour biomarkers. Biomarkers include not only protein routinely used as tumour markers but also genes and chromosomes. The limiting factor in the use of markers in the diagnosis of endometrial cancer is their lack of specificity. However, specific markers for endometrial cancer are the subject of much research attention. Although moderately elevated levels of markers are present in a number of inflammatory or non-malignant diseases, significantly increased levels of markers indicate the development of cancer. Recently, research has been focused on the identification of molecular changes leading to different histological subtypes of endometrial cancer. In this paper the authors reviewed several currently investigated markers. Progress in these investigations is very important in the diagnostics and treatment of endometrial cancer. In particular, the identification of novel mutations and molecular profiles should enhance our ability to personalise adjuvant treatment with genome-guided targeted therapy.

Microarray analysis on gene regulation by estrogen, progesterone and tamoxifen in human endometrial stromal cells

Epithelial stromal cells represent a major cellular component of human uterine endometrium that is subject to tight hormonal regulation. Through cell-cell contacts and/or paracrine mechanisms, stromal cells play a significant role in the malignant transformation of epithelial cells. We isolated stromal cells from normal human endometrium and investigated the morphological and transcriptional changes induced by estrogen, progesterone and tamoxifen. We demonstrated that stromal cells express appreciable levels of estrogen and progesterone receptors and undergo different morphological changes upon hormonal stimulation. Microarray analysis indicated that both estrogen and progesterone induced dramatic alterations in a variety of genes associated with cell structure, transcription, cell cycle, and signaling. However, divergent patterns of changes, and in some genes opposite effects, were observed for the two hormones. A large number of genes are identified as novel targets for hormonal regulation. These hormone-responsive genes may be involved in normal uterine function and the development of endometrial malignancies.

Molecular mechanisms of tamoxifen-associated endometrial cancer (Review)

Tamoxifen has been prescribed to millions of females for breast cancer prevention or treatment. However, tamoxifen is known to significantly enhance the risk of developing endometrial lesions, including hyperplasia, polyps, carcinomas, and sarcoma. Notably, tamoxifen-associated endometrial cancer often has a poor clinical outcome. Understanding the molecular mechanism of tamoxifen-induced endometrial cancer is essential for developing strategies that minimize tamoxifen’s effects on the endometrium without jeopardizing its breast cancer treatment effects. However, this understanding remains limited. Tamoxifen appears to mediate its effect on endometrial cells through estrogenic and non-genomic pathways, rather than introducing a genomic alteration as a carcinogen. Although tamoxifen functions as an agonist and promotes cell proliferation in endometrial cancer, it also displays antagonist activity towards some estrogen targets. Alterations in estrogen receptor-α and its isoforms, as well as the membrane associated estrogen receptor G protein-coupled receptor 30, have been observed with tamoxifen-exposed endometrial cells, and likely mediate the effects of tamoxifen on endometrial cancer cell proliferation and invasion. In addition, gene profile studies of short-term exposure to tamoxifen indicate that the majority of tamoxifen targets are tamoxifen-specific. However, the tamoxifen regulated gene targets that are involved in mediating the effects of long-term exposure to tamoxifen are not yet fully understood. Recent progress has indicated a potential role of unfolded protein response and mammalian target of rapamycin signaling in tamoxifen-associated endometrial cancer. In the future, studies focusing on long-term effects of tamoxifen exposure are required to understand the molecular mechanisms of tamoxifen-associated endometrial cancer.

MGMT promoter hypermethylation and K-RAS, PTEN and TP53 mutations in tamoxifen-exposed and non-exposed endometrial cancer cases

BACKGROUND

Tamoxifen has anti-oestrogenic and anti-tumour activity in the breast, but is oestrogenic and carcinogenic in the endometrium. It can induce experimental tumours by both hormonal and DNA-damaging mechanisms, but its carcinogenic mode of action in human endometrium remains unclear.

METHODS

We investigated whether an epigenetic mechanism, involving promoter hypermethylation of the gene for the DNA repair enzyme MGMT (O6-methylguanine DNA methyltransferase), was associated with K-RAS, TP53 and PTEN mutations in endometrial tumours from women treated with tamoxifen (TAM, n=30) or unexposed to the drug (EC, n=38).

RESULTS

There were significant (P<0.05) differences in tumour grade between the TAM and EC groups, with more favourable morphology in the latter. K-RAS mutations, predominantly G>A, occurred in small numbers in both groups. TP53 mutations were of mainly A>G, C>T and indel modifications in both groups, but more frequent in TAM cases. PTEN mutations dominated in EC tumours and were of the type that has large impact on protein function, such as indel or nonsense mutations. These observations alongside the mutational spectrum in PTEN suggest that the malignancies arise from different backgrounds, hence pointing to an effect of tamoxifen. Both groups displayed MGMT promoter hypermethylation. This coincided with mutations more frequently in the TAM (78%) than in the EC (50%) group, even though there were significantly (P<0.05) fewer mutations and methylations in TAM cases.

CONCLUSIONS

Although the difference in coincidence did not reach significance with the current sample size, the findings suggest that epigenetic processes may play a role in the way tamoxifen induces endometrial cancer.

Peroxidase-mediated dealkylation of tamoxifen, detected by electrospray ionization-mass spectrometry, and activation to form DNA adducts

Tamoxifen (TAM) is extensively used for the treatment and prevention of breast cancer. Associated with TAM treatment is a two- to eightfold increase in risk of endometrial cancer. To understand the mechanisms associated with this increased risk several pathways for TAM metabolism and DNA adduct formation have been studied. The purpose of this study was to investigate the role of peroxidase enzymes in the metabolism of TAM and its activation to form DNA adducts. Using advanced tandem mass spectrometry we have investigated the peroxidase-mediated metabolism of TAM. Incubation of TAM with horseradish peroxidase (HRP) and H(2)O(2) produced multiple metabolites. Electrospray ionization-MS/MS analysis of the metabolites demonstrated a peak at 301.3m/z with daughter ions at 183.0, 166.9, 128.9, and 120.9m/z, which identified the metabolite as metabolite E (ME). The levels of ME were significantly inhibited by the addition of ascorbic acid to the incubation mixture. Co-incubation of either TAM or ME and DNA with HRP and H(2)O(2) produced three DNA adducts with a RAL of 1.97±0.01×10(-7) and 8.45±2.7×10(-7). Oxidation of ME with MnO(2) produced metabolite E quinone methide (MEQM). Furthermore, incubation of either TAM or ME with HRP and H(2)O(2) resulted in formation of MEQM. Reaction of calf thymus DNA with MEQM produced three DNA adducts with a RAL of 9.8±1.0×10(-7). Rechromatography analyses indicated that DNA adducts 1, 2, and 3 formed in the HRP activation of either TAM or ME were the same as those formed by the chemical reaction of DNA with MEQM. The results of these studies demonstrate that peroxidase enzymes can both metabolize TAM to form the primary metabolite ME and activate ME to a quinone methide intermediate, which reacts with DNA to form adducts. It is possible that peroxidase enzymes or peroxidase-like activity in endometrium could contribute to the formation of DNA damage and genotoxic effects in endometrium after TAM administration.

Effects of tamoxifen on the endometrium and its mechanism of carcinogenicity

This study was conducted to clarify the clinicopathological characteristics of tamoxifen-associated endometrial carcinomas and its mechanisms of carcinogenesis. Seven patients with tamoxifen-associated endometrial carcinomas (TAM group) and 28 with sporadic endometrioid adenocarcinomas (EMC group) were included in the study. The clinicopathological factors, such as FIGO stage, histological type, grade, lymph node metastases, vascular invasion and the coexistence of hyperplasia, were investigated in both groups. The protein expression of p53, PTEN, hMLH1 and hMSH2 was investigated by immunohistochemistry. Microsatellite instability (MSI), k-ras and p53 mutation were also examined. In the TAM group, the histological types included five endometrioid, one endometrioid combined with serous and one clear cell type. The rates of coexistence with hyperplasia (five of seven cases) and vascular invasion (four cases) were significantly higher in the TAM group. The rates of stage III/IV (four cases) and lymph node metastasis (three cases) tended to be higher in the TAM group. Although there were no significant differences in PTEN, hMLH1 and hMSH2 expression between the two groups, p53 mutation was more frequent in three out of five cases (60%) in the TAM group compared with 2 of 15 cases in the EMC group (13.3%). No significant differences were observed concerning MSI and k-ras mutation in either group. These results suggested that TAM-associated endometrial carcinomas have overlapping biological characteristics of type I and type II endometrial carcinomas. This might explain the somewhat worse prognosis of these tumors than sporadic endometrioid carcinomas.

Monitoring of endometrial K-ras mutation in tamoxifen-treated patients with breast cancer

INTRODUCTION

A high incidence of endometrial K-ras mutations has been reported in tamoxifen (TAM)-treated patients with breast cancer. We examined the changes in the frequency of the endometrial K-ras mutations after the cessation of TAM treatment.

METHODS

DNA was extracted from fresh cytological or polypectomy samples of the endometrium in 28 patients who had undergone TAM treatment of breast cancer. Mutations were detected by an enriched polymerase chain reaction-enzyme-linked minisequence assay (Sumitomo Metal Industry, Inc, Tokyo, Japan). K-ras codon 12 mutations were monitored in these 28 patients.

RESULTS

An initial examination detected endometrial K-ras mutations in 13 of the 28 patients. However, repeated examinations performed after cessation of TAM treatment did not detect endometrial K-ras mutations in any of these 13 patients. No endometrial K-ras mutation has been detected in the repeated examinations performed for these patients for more than 2 years since the cessation of TAM treatment. In addition, the 15 patients who did not have endometrial K-ras mutations in the initial examination did not demonstrate them in repeat examinations.

CONCLUSIONS

The cessation of TAM treatment may reduce the risk of developing endometrial cancers through K-ras mutations.

Clinicopathological and molecular analysis of endometrial carcinoma associated with tamoxifen

Use of tamoxifen for treatment and prevention of breast cancer is becoming increasingly common. Tamoxifen has been associated with increased risk of endometrial carcinoma, although the exact mechanism of action is unknown. The aim of our study was to seek a possible correlation between endometrial carcinoma, tamoxifen exposure and MSI, PTEN, beta-catenin and K-ras abnormalities. A group of 18 patients with endometrial carcinoma following treatment with tamoxifen were selected. A control group included 15 patients with endometrial carcinoma and associated ovarian hyperthecosis and one patient with endometrial carcinoma and adult granulosa cell tumor of the ovary, chosen because both conditions are associated with increased production of estrogen and increased risk of endometrial carcinoma development. The second control group included 27 randomly selected consecutive patients with endometrial carcinoma without identifiable associated conditions. Immunostaining for beta-catenin was performed on all cases; DNA was extracted and amplified by PCR with primers for beta-catenin, K-ras and PTEN genes. BAT-25 and BAT-26 were analyzed to assess for MSI. There were 16 endometrioid endometrial carcinomas, one mixed carcinoma and one clear cell carcinoma among patients in the tamoxifen group. All patients with ovarian hyperthecosis and adult granulosa cell tumor had endometrioid endometrial carcinoma. In the random control group, there were 26 endometrioid endometrial carcinomas and one carcinosarcoma. Immunohistochemical and mutational analysis for beta-catenin showed abnormalities in 4/11 (36%) and 3/10 (30%) informative cases in the tamoxifen group; 7/16 (44%) and 4/15 (27%) informative cases, respectively in the ovarian hyperthecosis group and 1/27 random control cases (4%) (P<0.05). Patients with tamoxifen exposure had more K-ras mutations and fewer PTEN mutations and MSI as opposed to controls, but the results were not statistically significant. In conclusion, there was a direct relationship between tamoxifen exposure and overexpression of beta-catenin oncoprotein, which is known to play a major role in the pathogenesis of estrogen-driven, type I endometrial adenocarcinoma.

Postmenopausal status, hypertension and obesity as risk factors for malignant transformation in endometrial polyps

OBJECTIVES

We analyzed clinical data and pathological features of six cases of malignant endometrial polyps, to compare these with other examples reported in literature and to define the features of endometrial cancer arising in polyps. Moreover, to clarify the mechanisms of carcinogenesis in malignant endometrial polyps we examined the expression of cyclooxygenase-2 (COX-2), P53 and Ki 67 and their relationships with clinicopathologic characteristics.

METHODS

The surgical pathology files of the Pathology Department of Parma University were searched for cases of endometrial polyps with nests of endometrial carcinomas, from the years 2002-2005. Clinical records, histological slides of endometrial curetting, hysterectomy with salpingo-oophorectomy specimens and pelvic lymph nodes were reviewed in each case. The main pathological features analyzed were histological types of endometrial cancer and the stage of development of neoplasm. The presence of other malignancies in the genital tract were also considered. Immunohistochemical staining was done using antibodies COX-2, p53 and Ki 67.

RESULTS

In our study, all malignant endometrial polyps had been detected in postmenopausal women. The majority of our patients with malignant endometrial polyps had risk factors for the development of endometrial carcinoma such as hypertension, obesity and unopposed estrogen therapy. Unlike other studies, no patients had a history of previous breast carcinoma and Tamoxifen treatment. The most common subtypes of endometrial carcinoma in malignant polyps are endometrioid carcinoma and serous papillary carcinoma. Endometrial carcinoma arising in endometrial polyps is an early endometrial carcinoma with good prognosis, except for papillary serous carcinoma, which can be associated with multiple omental involvement, despite low stage of development in the uterus. Immunohistochemical study showed that COX-2 expression was found in cytoplasm of tumor cells and this was elevated in all cases, independently of the grade and the stage of development of the malignancy, histological subtype and deep invasion of myometrium. P53 and Ki 67 expression, detected in the nuclei of neoplastic cells, was not correlated with COX-2 immunoreactivity, but these markers were associated with more advanced stage, grading, and histologic subtypes of tumor.

CONCLUSIONS

Postmenopausal status, hypertension, obesity could all be considered as risk factors for carcinomatous transformation within endometrial polyps in women without a history of breast carcinoma and Tamoxifen treatment. However, our series is small (only six cases considered) and further studies are necessary to confirm this hypothesis. In the current study, immunohistochemical data reveal that COX-2 expression may be associated with the carcinogenesis in endometrial carcinomas arising in endometrial polyps, but this antibody is not correlated with tumor aggressiveness, P53 and Ki 67 expression. P53 and Ki 67 overexpression, instead, are associated with advanced stage, histologic subtype and deep myometrial invasion of neoplasm.

Endometrial carcinoma: pathology and genetics

In the Western world, endometrial carcinoma is the most common malignant tumour of the female genital tract and the fourth most common cancer in women after carcinomas of breast, colorectum, and lung. The annual incidence has been estimated at 10-20 per 100 000 women. In the United States, endometrial carcinoma accounts for approximately 6000 deaths per year. Two different clinicopathological subtypes are recognised: the oestrogen-related (type I, endometrioid) and the non-oestrogen related (type II, non-endometrioid). The clinicopathological differences are parallelled by specific genetic alterations, with type I showing microsatellite instability and mutations in PTEN, PIK3CA, K-Ras, and CTNNB1 (beta-catenin), and type II exhibiting p53 mutations and chromosomal instability. This article reviews the genetic changes of endometrial carcinogenesis in the light of morphological features of the tumours and their precursors.

Endometrial polyp with sex cord-like pattern

We report on an unusual endometrial polyp in a postmenopausal woman taking tamoxifen for 7 years after surgical resection of a breast carcinoma. A 63-year-old woman with endometrial thickening was submitted to hysteroscopy with biopsy, which revealed a polyp with a sex cord-like pattern. The hysterectomy specimen showed florid adenomyosis, and in the background, there were rare sex cord-like foci. Immunohistochemistry can be useful in differentiating sex cord-like elements from metastatic breast cancer to endometrium. This is, to our knowledge, the first observation in literature correlated to tamoxifen intake.

Tumorigenesis of K-ras mutation in human endometrial carcinoma via upregulation of estrogen receptor

OBJECTIVE

To investigate the tumorigenesis of mutant [12Asp]-K-ras in endometrial carcinoma and its relationship with ER.

METHODS

We constructed pcDI-[12Asp]K-ras4B by inserting full-length [12Asp]K-ras4B from human endometrial carcinoma Hec-1A cells, into pcDI vector. Cell proliferation of NIH3T3 after transfection with pcDI-[12Asp]K-ras4B was measured by MTT assay. The cell transformation was determined by colony formation and tumor nodule development. [12Asp]-K-ras4B-NIH3T3 cells were transfected with constitutively active pCMV-RafCAAX and dominant-negative pCMV-RafS621A. Cell growth was measured by MTT assay and [3H]thymidine incorporation. After transfected with pcDI-[12Asp]K-ras4B or pCMV-RafS621A, the cells were harvested for Western blot and reporter assay to determine the expression and transcriptional activity of ERalpha and ERbeta, respectively.

RESULTS

[12Asp]-K-ras4B enhanced NIH3T3 cells proliferation after 48 h post-transfection (P < 0.05). More colonies were grown 10 days after incubating pcDI-[12Asp]-K-ras4B-NIH3T3 cells (13.48%) than pcDI-NIH3T3 (4.26%) or untreated NIH3T3 (2.33%). The pcDI-[12Asp]-K-ras4B-NIH3T3 cells injected to the nude mice Balb/C developed tumor nodules with poor-differentiated cells after 12 days. An increase of ERalpha and ERbeta was observed in pcDI-[12Asp]-K-ras4B-NIH3T3 cells. RafS621A downregulated ERalpha and ERbeta expression. Estrogen induced the ER transcriptional activity by 5-fold in pcDI-NIH3T3 cells, 13-fold in pcDI-[12Asp]K-ras4B-NIH3T3 and 19-fold in HEC-1A. RafS621A suppressed the ER transcriptional activity.

CONCLUSIONS

K-ras mutation induces tumorigenesis in endometrium, and this malignant transformation involves Raf signaling pathway and ER.

Endometriumveränderungen nach Tamoxifen-Therapie

Tamoxifen belongs to the group of selective estrogen modulators (SERM) which bind to both the alpha and the beta-estrogen receptors. Depending on the type of tissue, tamoxifen has either an anti-estrogenic or an estrogenic effect on the cells. In the treatment of breast cancer, the anti-estrogenic effect is used. However, at the same time there is a predominant progestin-like and only mild estrogenic effect on the endometrium. Depending on the hormonal situation of the patient, tamoxifen can cause different morphological changes in the endometrium. On ultrasound, these changes are normally diagnosed as a thickening. However, endometrial hyperplasia or endometrial carcinoma is identified histologically in only a few cases. In the majority of cases, the diagnosis is endometrial atrophy or endometrial polyp. Other findings related to tamoxifen therapy are stromal decidualisation, regressive hyperplasia, and foci of mucinous, clear cell and serous metaplasia. The main reason for the diagnosis of endometrial hyperplasia on ultrasound could be fibrosis and edema along the border between the endometrium and myometrium. Still unsolved is the question of whether endometrial carcinomas developing after tamoxifen therapy belong mostly to type I (endometrioid) or type II (serous, clear cell) carcinomas. Only in rare cases do malignant neoplasms other than carcinomas develop after tamoxifen therapy. These are adenosarcomas, carcinosarcomas and endometrial stromal sarcomas.

Clinicopathologic review of malignant polyps in stage 1A carcinoma of the endometrium

OBJECTIVES

The aims of this study were to determine the incidence of malignant polyps in stage 1A endometrial cancer, to define the pathological features of such cancers, and to assess whether clinical outcome differs from similar cancers without a malignant polyp.

METHODS

We performed a retrospective pathological review of 107 cases of stage 1A endometrial cancer treated at two centers in New South Wales between January 1988 and July 2003. The presence of a malignant polyp was determined and a pathological description made of the tumor. Clinical data were collected, including prior tamoxifen usage, tumor recurrence and survival. The outcome of the malignant polyp group was compared to the same histological subtype not involving a malignant polyp.

RESULTS

The incidence of malignant polyps in our series was 32%. Malignant polyps occurred in all 8 cases involving a serous subtype. Precursor lesions of endometrial cancer were identified within malignant polyps. Three out of the four recurrences occurred in high-grade tumor subtypes and all four had a large primary tumor (size > or = 4 cm). When comparing the same subtype of tumor with and without a malignant polyp, there was no significant difference in clinical outcome.

CONCLUSIONS

Approximately one-third of stage 1A endometrial cancers are associated with a malignant polyp. Serous carcinoma commonly arises within an otherwise benign endometrial polyp. Malignant polyps offer an opportunity to identify precursors of endometrial carcinoma. Clinical outcome of stage 1A endometrial carcinoma was related to the histological subtype and the size of the tumor rather than the presence of a malignant polyp.

K-ras mutation in the endometrium of tamoxifen-treated breast cancer patients, with a comparison of tamoxifen and toremifene

The putative presence of a mutation in codon 12 of the K-ras gene was investigated in the endometrium of tamoxifen (TAM) and toremifene (TOR)-treated breast cancer patients. DNA was extracted from fresh cytologic samples of the endometrium in 86 TAM and 21 TOR-treated breast cancer patients. Mutations were detected by enriched PCR and an enzyme-linked mini-sequence assay (ELMA). K-ras mutation was found in 35 TAM-treated endometrial samples, and in only one TOR-treated endometrium (P<0.003). In 24 premenopausal patients, K-ras mutation was found in seven (43.8%) of 16 patients with less than 47 months of TAM treatment, while none was found in eight patients with more than 48 months of TAM treatment (P<0.03). In 62 postmenopausal-amenorrheic patients, K-ras mutation was found in three (15.8%) of 19 patients with less than 23 months of TAM treatment, while it was found in 16 (61.5%) of 26 patients with 24–47 months of TAM treatment and nine (52.9%) of 17 patients with more than 48 months of TAM treatment (P=0.002). The presence of K-ras mutation is significantly influenced by the duration of TAM treatment and menstrual status of the patients. TOR may have a lower potential genotoxicity than TAM.

Endometrial K-ras mutations in postmenopausal breast cancer patients treated with adjuvant tamoxifen or toremifene

PURPOSE

Long-term use of tamoxifen is associated with a two- to threefold increased risk of endometrial cancer in postmenopausal women. Toremifene is another triphenylethylene antiestrogen, which is as effective as tamoxifen in postmenopausal breast cancer. Thus far, its use has not been associated with an increased risk of endometrial cancer. K-ras codon 12 mutations seem to be important in endometrial carcinogenesis, and these mutations have been found in endometrial samples of patients on tamoxifen. The present study was undertaken to investigate if there is any difference in the frequency of endometrial K-ras mutations among patients treated with tamoxifen or toremifene.

METHODS

Endometrial samples were taken from 23 postmenopausal breast cancer patients (tamoxifen, n = 11; toremifene, n = 12) before and after 36 months of treatment. DNA was isolated from formalin-fixed paraffin-embedded samples using a routine proteinase K digestion protocol. K-ras mutations in codon 12 were screened using real-time PCR and melting curve analysis in LightCycler equipment. Wild-type PNA oligomer was used to increase the sensitivity of the assay.

RESULTS

All baseline samples contained wild-type K-ras, while 10/23 (43%) of the follow-up samples carried a codon 12 mutation. Mutations were identified in 3 of the 11 in the tamoxifen group and in 7 of the 12 in the toremifene group. Seven were transitions (G-->A), and three were transversions (two G-->T, one G-->C). One of the mutations in the toremifene group was associated with a polypoid endometrium. All the other mutations were found in an atrophic (n = 6) or proliferative (n = 3) endometrium.

CONCLUSIONS

Both tamoxifen and toremifene induce endometrial K-ras codon 12 mutations. The significance of this finding to endometrial carcinogenesis remains to be elucidated.

Genotoxic Mechanism of Tamoxifen in Developing Endometrial Cancer

Increased risk of developing endometrial cancers has been observed in women treated with tamoxifen (TAM), a widely used drug for breast cancer therapy and chemoprevention. The carcinogenic effect may be due to genotoxic DNA damage induced by TAM. In fact, TAM-DNA adducts were detected in the endometrium of women treated with this drug. TAM is alpha-hydroxylated by cytochrome P450 3A4 followed by O-sulfonation by hydroxysteroid sulfotransferase, and reacts with guanine residues in DNA, resulting in the formation of alpha-(N2-deoxyguanosinyl)tamoxifen adducts. During this metabolic process, short-lived carbocations are produced at the ethyl moiety of TAM as reactive intermediates. TAM-DNA adducts promote primarily G -->T transversions in mammalian cells. The same mutations have been frequently detected at codon 12 of the K-ras gene in the endometrial tissue of women treated with this drug. TAM-DNA adducts, if not readily repaired, may act as initiators, leading to development of endometrial cancers. The reactivity of TAM metabolites with DNA is inhibited in toremifene, where the hydrogen atom has been replaced by a chlorine atom at the ethyl moiety. Therefore, toremifene may be a safer alternative to TAM. This article describes an overview of the mechanism of TAM-DNA adduct formation, mutagenic events of this adduct, and detection of TAM-DNA adducts in the endometrium of women treated with TAM.