Martin C. Chang

Primary ex vivo cultures of human fallopian tube epithelium as a model for serous ovarian carcinogenesis

Recent studies suggest that some serous ovarian carcinomas (SOCs) arise from the fallopian tube (FT) epithelium rather than the ovarian surface epithelium. This hypothesis places emphasis on the FT secretory epithelial cell as a cell-of-origin. Herein, we report the development of a novel ex vivo primary human FT epithelium culture system that faithfully recapitulates the in vivo epithelium, as shown by morphological, ultrastructural and immunophenotypic analyses. Mass spectrometry-based proteomics reveal that these cultures secrete proteins previously identified as biomarkers for ovarian cancer. We also use this culture system to study the response of the FT epithelium to genotoxic stress and find that the secretory cells exhibit a distinct response to DNA damage when compared with neighboring ciliated cells. The secretory cells show a limited ability to resolve the damage over time, potentially leaving them more susceptible to accumulation of additional mutagenic injury. This divergent response is confirmed with in situ studies using tissue samples, further supporting the use of this ex vivo culture system to investigate FT epithelial pathobiology. We anticipate that this novel culture system will facilitate the study of SOC pathogenesis, and propose that similar culture systems could be developed for other organ site-specific epithelia.

Diagnosis of NUT midline carcinoma using a NUT-specific monoclonal antibody.

NUT midline carcinoma (NMC) is a uniformly lethal malignancy that is defined by rearrangement of the nuclear protein in testis (NUT) gene on chromosome 15q14. NMCs are morphologically indistinguishable from other poorly differentiated carcinomas, and the diagnosis is usually made currently by fluorescence in situ hybridization (FISH). As normal NUT expression is confined to testis and ovary, we reasoned that an immunohistochemical (IHC) stain for NUT would be useful in diagnosing NMC. To this end, we raised a highly specific rabbit monoclonal antibody, C52, against a recombinant NUT polypeptide, and developed an IHC staining protocol. The sensitivity and specificity of C52 staining was evaluated in a panel of 1068 tissues, predominantly diverse types of carcinomas (n=906), including 30u2009NMCs. Split-apart FISH for NUT rearrangement was used as a “gold standard” diagnostic test for NMC. C52 immunoreactivity among carcinomas was confined to NMCs. IHC staining had a sensitivity of 87%, a specificity of 100%, a negative predictive value of 99%, and a positive predictive value of 100%. Two new cases of NMC containing BRD4-NUT fusions were detected by C52 IHC, but missed by conventional FISH. In both instances, these tumors contained cryptic BRD4-NUT rearrangements, as confirmed by FISH using a refined set of probes. Some germ cell tumors, including 64% of dysgerminomas, showed weak NUT immunoreactivity, consistent with the expression of NUT in normal germ cells. We conclude that IHC staining with the C52 monoclonal antibody is a highly sensitive and specific test that reliably distinguishes NMC from other forms of carcinoma. The NUT antibody is being prepared for commercial release and will be available in the near future.

Long-term outcomes of hypofractionation versus conventional radiation therapy after breast-conserving surgery for ductal carcinoma in situ of the breast.

PURPOSEnWhole-breast radiation therapy (XRT) after breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS) may decrease the risk of local recurrence, but the optimal dose regimen remains unclear. Past studies administered 50 Gy in 25 fractions (conventional); however, treatment pattern studies report that hypofractionated (HF) regimens (42.4 Gy in 16 fractions) are frequently used. We report the impact of HF (vs conventional) on the risk of local recurrence after BCS for DCIS.nnnMETHODS AND MATERIALSnAll women with DCIS treated with BCS and XRT in Ontario, Canada from 1994 to 2003 were identified. Treatment and outcomes were assessed through administrative databases and validated by chart review. Survival analyses were performed. To account for systematic differences between women treated with alternate regimens, we used a propensity score adjustment approach.nnnRESULTSnWe identified 1609 women, of whom 971 (60%) received conventional regimens and 638 (40%) received HF. A total of 489 patients (30%) received a boost dose, of whom 143 (15%) received conventional radiation therapy and 346 (54%) received HF. The median follow-up time was 9.2 years. The median age at diagnosis was 56 years (interquartile range [IQR], 49-65 years). On univariate analyses, the 10-year actuarial local recurrence-free survival was 86% for conventional radiation therapy and 89% for HF (P=.03). On multivariable analyses, age <45 years (hazard ratio [HR] = 2.4; 95% CI: 1.6-3.4; P<.0001), high (HR=2.9; 95% CI: 1.2-7.3; P=.02) or intermediate nuclear grade (HR=2.7; 95% CI: 1.1-6.6; P=.04), and positive resection margins (HR=1.4; 95% CI: 1.0-2.1; P=.05) were associated with an increased risk of local recurrence. HF was not significantly associated with an increased risk of local recurrence compared with conventional radiation therapy on multivariate analysis (HR=0.8; 95% CI: 0.5-1.2; P=.34).nnnCONCLUSIONSnThe risk of local recurrence among individuals treated with HF regimens after BCS for DCIS was similar to that among individuals treated with conventional radiation therapy.

Evidence for biological effects of metformin in operable breast cancer: biomarker analysis in a pre-operative window of opportunity randomized trial

Metformin has therapeutic potential against breast cancer, but the mechanisms of action in vivo remain uncertain. This study examined biomarker effects of metformin in primary breast cancer in a preoperative window of opportunity trial. Non-diabetic women with operable invasive breast cancer were randomized to receive open label pre-operative metformin (500xa0mg daily for 1xa0week then 1xa0g twice daily for a further week) or as controls, not receiving metformin. Patients in both arms had a core biopsy pre-randomisation and again at the time of surgery. Immunohistochemistry for phospho-AMPK (pAMPK), phospho-Akt (pAkt), insulin receptor, cleaved caspase-3, and Ki67 was performed on formalin-fixed paraffin-embedded cores, scored blinded to treatment and analysed by paired t test. In metformin-treated patients, significant up-regulation of pAMPK (paired t test, pxa0=xa00.04) and down-regulation of pAkt (paired t test, pxa0=xa00.043) were demonstrated compared to the control group. Insulin receptor and serum insulin remained similar following metformin treatment compared with a rise in insulin receptor and insulin in controls. Significant falls in Ki67 and cleaved caspase-3 (paired t test, pxa0=xa00.044) were seen in the metformin-treated patients but not in the control group. Changes were independent of body mass index. These biomarker data suggest mechanisms for metformin action in vivo in breast cancer patients via up-regulation of tumor pAMPK, down-regulation of pAkt, and suppression of insulin responses reflecting cytostatic rather than cytotoxic mechanisms.

Embryonic Stem Cell Transcription Factors and D2-40 (podoplanin) as Diagnostic Immunohistochemical Markers in Ovarian Germ Cell Tumors

The embryonic stem cell transcription factors SOX2, NANOG, and OCT3/4 are involved in the regulation of germ cell tumor growth and differentiation. They, and D2-40 (podoplanin), an antigen expressed in seminomas, are emerging as useful diagnostic markers in testicular germ cell tumors. This study evaluates the use of these markers in ovarian tumors. Ovarian germ cell tumors (n=31) have distinct immunostaining profiles, depending on the type of differentiation as follows: dysgerminoma (SOX2−, NANOG+, OCT3/4+, D2-40+), embryonal carcinoma (SOX2+, NANOG+, OCT3/4+, D2-40−), immature teratomas (SOX2+, NANOG−, OCT3/4−, D2-40−), yolk sac tumors, and choriocarcinoma (SOX2−, NANOG−, OCT3/4−, D2-40−). In immature teratomas, SOX2 positivity was limited to neural and epithelial tissues, and OCT3/4 was positive only in scattered epithelial cells (<10% of cells). Nongerm cell tumors (n=57, including surface-epithelial stromal tumors and sex-cord stromal tumors) were negative for NANOG and D2-40. OCT3/4 was positive in 4 of 9 adult granulosa cell tumors (15% to 85% of cells). In a small number of surface-epithelial stromal tumors, SOX2 and/or OCT3/4 were variably positive (20% to 90% of cells). Of the markers, SOX2 and D2-40 discriminated between dysgerminoma and embryonal carcinoma. NANOG distinguished between either of these 2 tumors and nongerm cell tumors. The inclusion of these markers should therefore be considered in cases of pure or mixed ovarian germ cell tumors that are difficult to classify, and to exclude nongerm cell tumor mimics.

Immunohistochemical and clinicopathological correlation of the metastasis-associated gene 1 (MTA1) expression in benign and malignant pancreatic endocrine tumors.

Pancreatic endocrine tumors are rare tumors with unpredictable clinical behavior. No histological features or immunohistochemical markers reliably predict malignant progression and the molecular basis of progression of pancreatic endocrine tumors remains unknown. The metastasis-associated gene 1 is thought to play a role in transcription repression and estrogen receptor interaction and is overexpressed in several human cancers, including endocrine neoplasms. The purpose of this study was to analyze the expression of metastasis-associated gene 1 in pancreatic endocrine tumors for its possible role in malignant progression. Twenty-seven pancreatic endocrine tumors were identified from our archive. The mean age at presentation was 57 years (range 28–86); the male/female ratio was 1.25 to 1, and the mean size was 4.5u2009cm (0.1–18u2009cm). The clinical follow-up data were examined and tumors were classified according to the 2004 World Health Organization criteria as benign behavior (WHO 1.1), uncertain behavior (WHO 1.2), well-differentiated endocrine carcinoma (WHO 2), and poorly differentiated endocrine carcinoma (WHO 3). Histopathological and immunohistochemical stains were evaluated and metastasis-associated gene 1 expression scored semiquantitatively as absent (1+), weak (2+), moderate (3+), or strong (4+). Statistical analysis was performed using Kruskal–Wallis nonparametric analysis of variance with a significance level of 0.05. Metastasis-associated gene 1 expression was significantly higher in malignant tumors (n=17) with a mean staining intensity of 3.8 compared with 2.9 in benign tumors (n=10, P=0.046). The expression levels were significantly associated with WHO class (P=0.028), as well as size of tumor (P=0.029), and mitotic rate (P=0.035). Metastasis-associated gene 1 expression was associated with local invasion with borderline significance (0.062). We show that metastasis-associated gene 1 expression is significantly associated with malignant behavior in pancreatic endocrine tumors. This may suggest a potential role for metastasis-associated gene 1 in the malignant progression and metastasis and its use as biomarker for malignant pancreatic endocrine tumors.

The impact of tissue block sampling on the detection of p53 signatures in fallopian tubes from women with BRCA 1 or 2 mutations (BRCA+) and controls

The tubal p53 signature is a putative precursor to pelvic serous carcinoma, but its frequencies in women with inherited mutations in the BRCA1 or BRCA2 genes (BRCA+) and controls has been controversial. An initial section and two levels (100–200u2009μm) from every block in BRCA+ (24) and control tubes (40) were stained for p53. The frequency of p53 signatures was computed between the populations and across the three levels from each block, and analyzed by Fisher exact test. A total of 17 (71%) BRCA+ and 20 (50%) control tubes were p53 signature positive (P=0.12); 21 and 16% of all tissue blocks sectioned harbored signatures (P=0.29), and 76 and 67% were found in the fimbria. In 49 and 32% of p53 signature positive cases in the two groups, the p53 signatures were not discovered until the second or third round of sectioning. In all, 38 and 40% of BRCA+ and control subjects harbored p53 signatures in more than one focus in a single block. In one case (BRCA+), a highly atypical proliferation was identified in one serial section. The p53 signatures are more common than previously reported and the frequency of detection increases as a function of sectioning through the tissue block, both in absolute frequency and in numbers of p53 signatures detected in a given block. There is a trend for a higher absolute frequency of p53 signatures (71 vs 50%; P=0.12) in BRCA+ subjects, but this is not reflected in a greater average number of p53 signatures or positive blocks per case. This study underscores the importance of systematic immunohistochemical examination of fallopian tubes when conducting epidemiological studies that compare the frequency of p53 signatures in different populations. Attention to this detail is critical when exploring risk factors germane to early serous carcinogenesis.

Endocervical adenocarcinoma in situ with ovarian metastases: A unique variant with potential for long-term survival

Adenocarcinoma in situ (AIS) of the endocervix is typically confined to the cervix, but may be extensive. We report 2 cases of extensive AIS-one with intraendometrial spread-that recurred after cone biopsy and were associated with ovarian metastases. In both cases, primary and metastatic tumors were positive for human papillomavirus 16. Both patients are currently disease-free and one has had no recurrence after a follow-up period of 145 months. Extensive, recurring AIS is a rare variant that may be unique for its risk of coincident ovarian involvement. However, ovarian spread, albeit rare, does not invariably result in an adverse outcome.

Papillomaviruses and Cervical Neoplasia

The evolution of molecular biology and related technologies and their application to medical sciences has rapidly altered our perception of the pathogenesis and therapeutic approach to intraepithelial squamous lesions of the lower female genital tract. As with any new technology, the knowledge can be applied on several different levels. For example, it may broaden our understanding of a disease process without changing the therapeutic approach, or it may change our perceptions of disease and indirectly benefit the patient by providing a more knowledgeable physician. Ultimately these techniques, such as viral DNA detection, may have clinical utility, provided they are tested and proven useful within the context of scientific inquiry.

High-grade and low-grade pelvic serous neoplasms demonstrate differential p53 immunoreactivity in peritoneal washings.

Objective: Serous neoplasms of the female pelvis share a müllerian phenotype. Unlike low-grade serous neoplasms (LGSNs), high-grade serous carcinomas (HGSCs) commonly display p53 mutations. The current study correlates p53 immunoreactivity in peritoneal washings with the cytologic interpretation and histology of the corresponding serous neoplasm. Study Design: Peritoneal washings from consecutive cases of pelvic serous neoplasms were identified (n = 45, 31 HGSCs and 14 LGSNs), with a control population selected from benign resections. Immunoreactivity for p53 was scored as a percentage of positive epithelioid cells by blinded manual cell count. Results: Washings from LGSNs and HGSCs were cytomorphologically positive with similar frequency (57 vs. 77%, respectively, p = 0.15, Fisher’s exact test). Immunoreactivity for p53 was not predictive of morphologic positivity. The percentage of p53-positive cells was higher in HGSCs (47 ± 42%), compared to LGSNs (9 ± 9%) and negative controls (2 ± 2%, n = 10). The difference in p53 immunoreactivity was statistically significant (p < 0.00009, ANOVA). Conclusions: The proportion of p53 immunoreactive cells was higher in cases of HGSCs, reflecting the importance of p53 mutations in high-grade serous tumorigenesis. The presence of p53 staining is not diagnostic for neoplastic cells; however, peritoneal washings are potential specimens in the investigation of serous neoplasia.