Impact of Primary Site Surgical Resection on Survival in Stage IV Breast Cancer

Background: Currently, primary treatments for stage IV breast cancer are radiation and systemic therapy which include chemotherapy, endocrine therapy and targeted therapy. Surgical resection of primary tumor is usually done for tumor-related complications. A recent review suggested that surgery may improve long-term survival in stageIV breast cancer patients. We evaluated the impact of primary site surgical resection on survival in such patients.Material and Methods: We reviewed the records of stage IV breast cancer patients treated at Seoul National University Hospital between 1992 and 2008. Clinical and tumor characteristics, systemic and local treatments were compared for the surgically versus nonsurgically treated patients.Results: Of 199 patients identified, 111(55.8%) recevied surgical excision of their primary tumor and 88(44.2%) did not. The mean survival of surgically treated patients was 67 months versus 52 months for patients those who did not(p=0.0276). In multivariate analysis, after adjustment for ER status, visceral metastasis, number of metastatic sites and herceptin treatment, surgery remained an independent factor associated with improved survival(HR 0.547[95%CI 0.359-0.971] p=0.001).Discussion: Surgical resection of the primary tumor in stage IV breast cancer patient was independently associated with improved survival, even after adjustment for other factors associated with survival. Randomized prospective trials are needed to validate these findings.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3117.

The Early Prediction of Response to Neoadjuvant Chemotherapy Using MRI

Purpose: Neoadjuvant chemotherapy is an effective method for down-staging the primary tumor before surgery. However, some of patients do not respond. In these patients, neoadjuvant chemotherapy is just an ineffective, toxic and expensive procedure. Therefore, it is very important to find the reliable method to differentiate the responder from non-responder as early as possible. In order to evaluate the role of magnetic resonance imaging (MRI) for the assessment of tumor response, we examined the correlation between the early MRI changes after the 1st cycle of neoadjuvant chemotherapy and later pathologic response after the 3rd cycle of neoadjuvant chemotherapy.Patients and method: 31 breast cancer patients who underwent neoadjuvant chemotherapy prior to surgery were analyzed. The baseline MRI was taken before neoadjuvant chemotherapy. Anthracycline plus taxane were administered to all patients. Post-chemotherapy MRI assessment was done just before the 2nd cycle of neoadjuvant chemotherapy. If the primary tumor was reduced more than 20% in the product of the longest and perpendicular diameter, those cases were classified as responders. Surgery was performed after the 3rd cycle of neoadjuvant chemotherapy. The pathologic response was assessed by measuring pathologic tumor size of viable tumor cells. Sensitivity, specificity, positive predictive value, and negative predictive value of MRI findings were calculated on the basis of histopathological examination.Results: Total 31 patients were examined. Of these patients, 2 patients had bilateral breast cancer. Therefore, a total of 33 lesions were evaluated. The median tumor size on baseline MRI was 4.5cm (range:2.1-10.0cm). 27 cases were classified as responders on early MRI findings. Of these cases, pathologic response was confirmed in 26 cases after surgery. Six cases were classified as non-responder on MRI. In this group, 3 cases showed pathologic response and 3 cases did not. Sensitivity, specificity, positive predictive value and negative predictive value of early MRI findings for the prediction of pathologic response were 89.7%, 75.0%, 96.3% and 50.0%, respectively.Conclusion: Post-chemotherapy MRI after the 1st cycle of neoadjuvant chemotherapy could differentiate responders from non-responders with high accuracy. It would be helpful to determine whether the chemotherapy regimen should be continued or not in the early phase of neoadjuvant therapy.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6057.

A new compound, 1H,8H-pyrano[3,4-c]pyran-1,8-dione, suppresses airway epithelial cell inflammatory responses in a murine model of asthma

Clinical and experimental studies have established eosinophilia as a sign of allergic disorders. Activation of eosinophils in the airways is believed to cause epithelial tissue injury, contraction of airway smooth muscle and increased bronchial responsiveness. As part of the search for new antiasthmatic agents produced by medicinal plants, the effects of 270 standardized medicinal plant extracts on cytokine-activated A549 human lung epithelial cells were evaluated. After several rounds of activity-guided screening, the new natural compound, 1H,8H-Pyrano[3,4-c]pyran-1,8-dione (PPY), was isolated from Vitex rotundifolia L. To elucidate the mechanism by which the anti-asthmatic responses of PPY occurred in vitro, lung epithelial cells (A549 cell) were stimulated with TNF-alpha, IL-4 and IL-1beta to induce the expression of chemokines and adhesion molecules involved in eosinophil chemotaxis. PPY treatments reduced the expression of eotaxin, IL-8, IL-16 and VCAM-1 mRNA significantly. Additionally, PPY reduced eotaxin secretion in a dose-dependent manner and significantly inhibited eosinophil migration toward A549 medium. In addition, PPY treatment suppressed the phosphorylation of p65 and ERK1/2, suggesting that it can inhibit the MAPK/NF-KB pathway. To clarify the anti-inflammatory and antiasthmatic effects of PPY in vivo, we examined the influence of PPY on the development of pulmonary eosinophilic inflammation in a murine model of asthma. To accomplish this, mice were sensitized and challenged with ovalbumin (OVA) and then examined for the following typical asthmatic reactions: an increase in the number of eosinophils in BALF; the presence of Th2 cytokines such as IL-4 and IL-5 in the BALF; the presence of allergen-specific IgE in the serum; and a marked influx of inflammatory cells into the lung. Taken together, our results revealed that PPY exerts profound inhibitory effects on the accumulation of eosinophils into the airways while reducing the levels of IL-4, IL-5, and IL-13 in the BALF. Therefore, these results suggest that PPY may be useful as a new therapeutic drug for the treatment of allergic asthma.

Value of preoperative staging of breast cancer patients using computed tomography to detect asymptomatic lung and liver metastasis

1105

Background: Preoperative clinical staging in breast cancer patients is important to determine the most appropriate treatment plans and to predict prognosis for individual patients. Identifying unexpected distant metastases in newly diagnosed breast cancer patients frequently alters initial treatment plans. Routine imaging studies to detect lung or liver metastasis is not indicated in patients with early and operable breast cancer. A recent study showed that routine use of chest radiograph and liver ultrasound does not provide much diagnostic benefit in early breast cancer patients. Methods: We aimed to investigate the value of preoperative computed tomography to detect asymptomatic liver and lung metastasis in breast cancer patients. We performed preoperative CT for 667 breast cancer patients to detect lung and liver metastasis among 1,636 primary breast cancer patients who had been diagnosed and treated between January 2006 and December 2007 at Seoul National University Hospital. Results: CT showed abnormal findings (suspicious of metastasis or indeterminate nodules) in 78 patients (10.5%). Among these, abnormal finding in 13 patients (1.7%) turned out to be true metastatic lesions. There was no CT-detected lung or liver metastasis in patients with T1 tumor and 4 metastases in patients with T2 tumor. There was no CT-detected lung or liver metastasis in patients with negative axillary lymph node metastasis. When patients were classified according to the AJCC staging, CT-detected true metastatic lesions were only present in stage III patients (13 out of 173 patients, 7.5%). The true metastatic lesions in lung or liver were all small sized nodules, ranging from 0.3cm to 1.2cm in largest diameters. In seven patients, the CT-detected metastatic lesions were less than 1cm which is in contrast with the previous studies. Conclusions: Our results demonstrated the lack of usefulness in performing routine CT exams to detect asymptomatic liver and lung metastasis in early breast cancer patients. Staging CT might be useful in stage III patients, since 13 (7.5%) patients were upstaged to stage IV by the use of CT.

No significant financial relationships to disclose.

Underweight and breast cancer recurrence and death

e22054

Background: The association of body mass index or body weight and breast cancer outcome is controversial. Furthermore, the impact of underweight on breast cancer recurrence and death has not been adequately addressed. Methods: We investigated this issue in a large nation-wide database of 14,039 Korean breast cancer patients (Korean Breast Cancer Registry). Furthermore, to test whether the association was due to more frequent non-cancer death in underweight women, we used breast cancer recurrence data of 4,345 women from single institution (Seoul National University Hospital). Results: The results from Korean Breast Cancer Registry data showed significantly lower overall survival in underweight patients compared to normal weight after adjusting known prognostic factors [hazard ratio=1.36 (95% CI 1.08–1.72)], which was not observed in obese patients. The association between body mass index and breast cancer recurrence was further investigated in Seoul National University Hospital data. Underweight women had significantly higher risk of distant metastasis and local recurrence of breast cancer [hazard ratio=1.86 (95% CI 1.25–2.76) and 2.62 (95% CI 1.55–4.41), respectively]. Conclusions: These findings suggest that underweight could be considered as high risk factor of death and recurrence after breast cancer surgery.

No significant financial relationships to disclose.

Triple negative phenotype: not affecting survival in young patients with operable breast cancer

Abstract #1083

Purpose: To investigate the clinicopathological characteristics and outcomes of triple negative breast cancer in young patients.
 Experimental Design: We analyzed 1,498 patients with primary invasive breast cancer who underwent surgery between January 2000 and December 2003. Patients were divided into those < 40 and ≥ 40 years old and into triple negative and non-triple negative groups.
 Results: A total of 326 (21.8%) were aged < 40; relative to patients ≥ 40 years old, the younger group showed larger tumor size, higher lymph node positivity, and elevated Ki-67 index. Recurrence-free survival (RFS; P = 0.0002) and overall survival (OS; P = 0.0483) were significantly lower in the younger group. Three hundred seventy four patients (25.0%) had the triple negative phenotype, and of which 93 (24.9%) were < 40 years old. Univariate survival analysis showed that the triple negative phenotype was not a prognostic factor for either RFS or OS in the younger group. In the older group, however, the triple negative phenotype was a significant prognostic factor for both RFS (P = 0.0103) and OS (P = 0.0081) by univariate analysis, and it remained a significant prognostic factor for OS by multivariate analysis (hazard ratio, 1.9; 95% confidence interval, 1.09-3.44; P = 0.025). When the non-triple negative group was subdivided into luminal and HER2 subtypes, the HER2 subtype showed the worst OS in both age groups (P < 0.001), followed by the triple negative group. However, the difference between the HER2 subtype and the triple negative group was significant only in the younger group (P = 0.0064), but not in the older group (P = 0.1446).
 Conclusions: Triple negative phenotype did not affect survival in patients < 40 years old, because of the markedly poorer survival of non-triple negative tumors of the HER2 subtype in this age group.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1083.

Age and HER2 expression status affect the accuracy of preoperative MRI in predicting tumor extent after neoadjuvant chemotherapy

Abstract #5108

Introduction: Neoadjuvant chemotherapy (NAC) can increase the breast conservation rate and provides prognostic information by identifying patients with pathologic complete remission (pCR). While breast conservation can be safely done in patients who show response to NAC, the presence of chemotherapy-induced fibrosis and the heterogeneous patterns of tumor shrinkage may mislead the determination of residual tumor extent during breast conserving surgery. Recent reports show improved preoperative assessment of residual tumor extent after NAC by performing preoperative breast magnetic resonance imagining (MRI) when compared to conventional methods. In this study, we evaluated the accuracy of preoperative breast MRI in predicting residual tumor extent in patients who underwent NAC, and investigated the factors which may influence its accuracy in a relatively large cohort of patients.
 Materials and Methods: From Jan 2006 to Feb 2008, 195 non-metastatic breast cancer patients received NAC and surgery in Department of Surgery, Seoul National University Hospital. In all patients, preoperative breast MRI was performed in addition to physical examination, mammography, and ultrasonography (USG) to estimate the residual tumor extent. The results were compared to pathologic tumor sizes, and the accuracy of MRI was determined by simple regression analysis. By using the results of immunohistochemical staining, patients were divided into molecular subtypes, and the accuracy of MRI was compared between each subtypes. To identify a subgroup of patients who might benefit from preoperative MRI, the association of MRI accuracy and various clinicopathologic features as well as molecular markers were investigated using linear regression analysis.
 Results: The mean age of the patients was 45.5 (±9.4) and mean pathologic tumor size was 4.9 (±2.1) cm. pCR was achieved in 31 patients (15.8%). Preoperative MRI and USG showed similar correlation with pathologic invasive tumor size measured from resected specimens (Pearson Coefficient of 0.492 and 0.462, respectively). However, MRI showed superior correlation with tumor extent when the size of surrounding in situ lesions were taken into consideration (Pearson Coefficient of 0.584 for MRI and 0.495 for USG). MRI showed highest correlation with pathologic tumor size in triple negative subtype and lowest correlation in HER2 subtype. Multivariate analysis showed older age (>45 yrs) and HER2 negativity as independent predictors of MRI accuracy. Mammographic density and initial tumor size did not have significant association with MRI accuracy.
 Conclusion: Preoprative MRI had high correlation with the extent of residual invasive and in situ tumor size after NAC. The accuracy of MRI was highest in patients with triple negative subtype. Multivariate analysis suggested age and CerbB2 expression as independent predictors of MRI accuracy. Although our results need further validation in a prospective setting, this results may provide a basis for selecting patients in whom the benefit of MRI can be maximized.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5108.

A potential serum panel for breast cancer diagnosis: ongoing clinical validation for its clinical implication

Abstract #5006

Although every effort has been made to discover single potent biomarkers in oncology, the promising single biomarker often loses its clinical potency in the course of clinical validations. We aimed to construct and verify a biomarker panel with multiple proteins for breast cancer diagnosis. Using Surface-Enhanced Laser Desorption/ Ionization Time-of-Flight mass spectrometry (SELDI-TOF-MS) and microbead array system, epidermal growth factor (EGF), vascular cell adhesion molecule-1 (VCAM-1), CD40L, vitronectin, plasminogen activation inhibitor-1 (PAI-1), vitamin-D binding protein (VDBP), C-reactive protein (CRP), kininogen, apolipoprotein A1 and proapolipoprotein A1 were identified and validated as useful biomarkers for detection of breast cancer. The multiplexing panel (MP) which was constructed by combining algorithm (random forest, support vector machine) with above biomarkers showed that the diagnostic accuracy approached 91% in 216 test samples. A following double blind test verified that the diagnostic accuracy of the MP was 68% with an additional validation set including sera from 49 patients with breast cancer and 51 healthy women (sensitivity=74%; 95% confidence interval (CI)=58.9–85.0%, specificity=62.7%; 95% CI=48.1–75.9%, positive predictive value=65.5%; 95% CI=55.7-75.3%, negative predictive value=71.7%; 95% CI=61.7-80.35%). We suggest that these results support the potential use of the MP as an early detector of breast cancer. In order to validate the role and potency of the MP in routine clinical practice, a large scale clinical validation in a cohort consisting of 500 patients with breast cancer and the same number of healthy women are underway and the results will be released in the near future.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5006.

Anoikis-resistant MDA-MB-231 cells: characteristics and pathway analysis

Abstract #2062

Background : Apoptosis in response to inappropriate adhesion or lack of adhesion has been termed anoikis. Resistance to anoikis is regarded as a prerequisite for invasion and metastasis in cancer cells. Recently many studies were performed to understand mechanism of anoikis resistance. However, there have been few studies on the role and mechanism of anoikis resistance in cancer cells.
 Materials and Methods : Anoikis-resistant MDA-MB-231 cells were induced and selected through culture on polyhydroxyethylmethacrylate (Poly-HEMA) substratum and invasiveness by matrigel invasion assay and drug-resistance to doxorubicin were checked. At the same time, expression of genes were evaluated in anoikis-resistant and adherent MDA-MB-231 cells by cDNA microarray. Pathway analysis on high-expressed genes in anoikis-resistant cells was performed by software(Ingenuity Pathway Analysis)
 Results : Invasion assays revealed that anoikis-resistant cells were more invasive than adherent cells. Anoikis-resistant cells were also more resistant to doxorubicin than adherent cells. Genes related to NF-kB pathway were highly expressed in anoikis-resistant cells. Therefore, the effect of Bay11-7085, inhibitor of NF-kB, on the growth of anoikis-resistant MDA-MB-231 cells was tested. The blockage of NF-kB pathway inhibited the growth of anoikis-resistant MDA-MB-231 cells.
 Conclusion : These results demonstrated that anoikis resistance was associated with increased invasiveness and resistance to chemotherapeutic agents and that NF-kB pathway involved in anoikis resistance.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2062.

Ki-67 gives additional prognostic information on St Gallen 2007 and Adjuvant! Online risk categories in early breast cancer

Abstract #1086

Purpose: We sought to determine the significance of Ki-67, one of the tumor cell proliferation indexes, as a useful prognostic factor in early breast cancer.
 Patients and Methods: 1,080 consecutive patients with stage I or II breast cancer operated between 1998 and 2003 were enrolled. Patients were categorized based on the 2007 St. Gallen consensus and Adjuvant! Online. The expression of Ki-67 in the tumor was assayed using immunohistochemistry (cut-off value: 10%).
 Results: Univariate analysis revealed that tumor size, lymph node involvement, histologic grade, estrogen receptor, progesterone receptor, bcl-2, and Ki-67 (≥10%) were significant for both overall survival (OS) and distant metastasis-free survival (DFS). Of them, lymph node involvement and high Ki-67 expression were identified as independent prognostic factors for OS at multivariate analysis. The survivals of intermediate- and high-risk groups according to 2007 St Gallen consensus were further separated by Ki-67 expression level (5-yr DFS rate=93.3% vs 86.6% for Ki-67<10% and ≥10%, respectively in intermediate-risk group (p=.001); 5-yr DFS rate=83.1% vs 61.5% for Ki-67<10% and ≥10%, respectively in high-risk group (p=.006)). The survivals of low- and high-risk groups according to Adjuvant! Online were further separated by Ki-67 expression level [5-yr DFS rate=97.8% vs 89.5% for Ki-67<10% and ≥10%, respectively in low-risk group (p=.010); 5-yr DFS rate=90.4% vs 82.6% for Ki-67<10% and ≥10% in high-risk group (p=.005)).
 Conclusion: Ki-67 was an independent prognostic factor for DFS and OS in early breast cancer, and could give additional prognostic information on the risk grouping by 2007 St Gallen consensus and Adjuvant! Online.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1086.

Gemcitabine pulmonary toxicity in ovarian cancer

BACKGROUND

A case of gemcitabine-induced lung toxicity is reported in a woman with stage IIIc ovarian papillary serous carcinoma.

CASE

An 83-year-old woman with stage IIIc ovarian serous papillary carcinoma diagnosed in 2001 underwent suboptimal cytoreductive surgery followed by carboplatin-paclitaxel chemotherapy. Initially in remission following chemotherapy, the disease subsequently progressed over the next 5 years. The patient received gemcitabine palliative chemotherapy. She developed significant pulmonary toxicity consistent with drug-induced interstitial pneumonitis, which improved with steroid therapy.

CONCLUSION

Gemcitabine, a second-line chemotherapy agent for the treatment of ovarian cancer, may rarely cause a serious or even fatal condition of pulmonary lung toxicity.

Reduced meiotic recombination on the XY bivalent is correlated with an increased incidence of sex chromosome aneuploidy in men with non-obstructive azoospermia

Both aberrant meiotic recombination and an increased frequency of sperm aneuploidy have been observed in infertile men. However, this association has not been demonstrated within individual men. The purpose of this study was to determine the association between the frequency of recombination observed in pachytene spermatocytes and the frequency of aneuploidy in sperm from the same infertile men. Testicular tissue from seven men with non-obstructive azoospermia (NOA) and six men undergoing vasectomy reversal (controls) underwent meiotic analysis. Recombination sites were recorded for individual chromosomes. Testicular and ejaculated sperm from NOA patients and controls, respectively, were tested for aneuploidy frequencies for chromosomes 9, 21, X and Y. There was a significant increase in the frequency of pachytene cells with at least one achiasmate bivalent in infertile men (12.4%) compared with controls (4.2%, P = 0.02). Infertile men also had a significantly higher frequency of sperm disomy than controls for chromosomes 21 (1.0% versus 0.24%, P = 0.001), XX (0.16% versus 0.03%, P = 0.004) and YY (0.12% versus 0.03%, P = 0.04). There was a significant correlation between meiotic cells with zero MLH1 foci in the sex body and total sex chromosome disomy (XX + YY + XY) in sperm from men with NOA (r = 0.79, P = 0.036).

Discontinuities and unsynapsed regions in meiotic chromosomes have a trans effect on meiotic recombination of some chromosomes in human males

During meiosis, homologous chromosome pairing and synapsis are essential for subsequent meiotic recombination (crossing-over). Discontinuous regions (gaps) and unsynapsed regions (splits) were most frequently observed in the heterochromatic regions of bivalent synaptonemal complex (SC) 9, and we have previously demonstrated that gaps and splits significantly altered the distribution of MLH1 recombination foci on SC 9. Here, immunofluorescence techniques (using antibodies against SC proteins and the crossover-associated MLH1 protein) were combined with a centromere-specific fluorescence in situ hybridization technique that allows identification of every individual chromosome. The effect of gaps/splits on meiotic recombination patterns in autosomes other than chromosome 9 during the pachytene stage of meiotic prophase was then examined in 6,026 bivalents from 262 pachytene cells from three human males. In 64 analyzed cells with a gapped SC 9, the frequency of MLH1 foci in SCs 5 and 10 and in SC arms 10q, 11p and 16q was decreased compared to 168 analyzed cells with a normally-synapsed SC 9 (controls). In 24 analyzed cells with splits in SC 9, there was a significant reduction in MLH1 focus frequency for SC 5q and the whole SC5 bivalent. The positioning of MLH1 foci on other SCs in cells with gapped/split SC 9 was not altered. These studies suggest that gaps and splits not only have a cis effect, but may also have a trans effect on meiotic recombination in humans.

Analysis of non-crossover bivalents in pachytene cells from 10 normal men

BACKGROUND

Bivalents with no recombination foci (possible achiasmates) are unable to orient properly on the metaphase plate or to segregate chromosomes to daughter cells. Non-crossover bivalents are known to cause meiotic arrest in various organisms.

METHODS

Individual non-crossover bivalents were identified in 886 pachytene cells (19 492 bivalents) from testicular biopsies of 10 normal men. Fluorescence staining combined with centromere-specific multicolour fluorescence in situ hybridization (cenM-FISH) was used to identify mismatch repair gene mutation of human mutL homologue 1 (MLH1) recombination foci along each bivalent synaptonemal complex (SC).

RESULTS

A total of 60 autosomal non-crossovers (SCs without an MLH1 focus) were found, and of these, chromosomes 21 (2.1%) and 22 (1.7%) had a significantly higher proportion than chromosomes 11, 12, 19 (each 0.1%), 13 (0.2%), 14 (0.6%), 16 (0.5%) and 15, 17, 18, 20 (each 0.3%) (P < 0.05). Sex chromosome univalents had a frequency of 27%, higher than that observed in any autosomal bivalent (P < 0.0001).

CONCLUSIONS

These results suggest that G-group chromosomes and sex chromosomes are most susceptible to having no recombination foci and thus would be more susceptible to non-disjunction during spermatogenesis. This is consistent with previous observations from sperm karyotyping and FISH analysis, which demonstrate that chromosomes 21 and 22 and the sex chromosomes have a significantly increased frequency of aneuploidy compared with other autosomes.

Immunofluorescent synaptonemal complex analysis in azoospermic men

The molecular cause of germ cell meiotic defects in azoospermic men is rarely known. During meiotic prophase I, a proteinaceous structure called the synaptonemal complex (SC) appears along the pairing axis of homologous chromosomes and meiotic recombination takes place. Newly-developed immunofluorescence techniques for SC proteins (SCP1 and SCP3) and for a DNA mismatch repair protein (MLH1) present in late recombination nodules allow simultaneous analysis of synapsis, and of meiotic recombination, during the first meiotic prophase in spermatocytes. This immunofluorescent SC analysis enables accurate meiotic prophase substaging and the identification of asynaptic pachytene spermatocytes. Spermatogenic defects were examined in azoospermic men using immunofluorescent SC and MLH1 analysis. Five males with obstructive azoospermia, 18 males with nonobstructive azoospermia and 11 control males with normal spermatogenesis were recruited for the study. In males with obstructive azoospermia, the fidelity of chromosome pairing (determined by the percentage of cells with gaps [discontinuities]/splits [unpaired chromosome regions] in the SCs, and nonexchange SCs [bivalents with 0 MLH1 foci]) was similar to those in normal males. The recombination frequencies (determined by the mean number of MLH1 foci per cell at the pachytene stage) were significantly reduced in obstructive azoospermia compared to that in controls. In men with nonobstructive azoospermia, a marked heterogeneity in spermatogenesis was found: 45% had a complete absence of meiotic cells; 5% had germ cells arrested at the zygotene stage of meiotic prophase; the rest had impaired fidelity of chromosome synapsis and significantly reduced recombination in pachytene. In addition, significantly more cells were in the leptotene and zygotene meiotic prophase stages in nonobstructive azoospermic patients, compared to controls. Defects in chromosome pairing and decreased recombination during meiotic prophase may have led to spermatogenesis arrest and contributed in part to this unexplained infertility.

Temporal progression of recombination in human males

To date, immunocytology has been used in humans to detect a limited number of meiotic proteins: components of the synaptonemal complex (SCP1 and SCP3) and some proteins known to participate in recombination events, such as MLH1 or RAD51. However, the colocalization or coexistence of proteins known to participate during the different stages of human meiosis remains largely unstudied, and these studies could provide important clues about the mechanics of recombination. This work reports the relative timing and localization of five different meiotic proteins that have previously been implicated in human homologous recombination [RAD51, replication protein A (RPA), MSH4, MLH1 and MLH3]. MSH4 foci appear concurrently with synapsis initiation at zygotene, shortly after the first RAD51 foci are detected. The presence of RPA in MSH4 foci was noted, suggesting that these two proteins may act co-operatively. Both RPA and MSH4 foci reach maximal numbers at the end of zygotene, when synapsis is concluding. From this point, RPA foci all but disappear by the end of pachytene, whereas MSH4 foci decline to a stable number at mid-pachytene, where they localize with MLH1/MLH3 recombination sites. We discuss a possible role for MSH4 in synapsis initiation and/or maintenance.

Male infertility in reciprocal translocation carriers: the sex body affair

Previous reports have linked chromosomal reorganization and spermatogenic failure. In this context, it has long been known that reciprocal translocation carriers are more likely to have anomalies in the meiotic process, including fertility failures. It has also been proposed that this fertility failure may be a consequence of an association between the translocated chromosomes and the sex body. In this work, we review different hypotheses explaining meiotic failure in these carriers, and propose a model that relates meiotic abnormalities with both sex body-translocation association and different checkpoints that are known to operate during meiosis.