HER2 as a potential therapeutic target on quiescent prostate cancer cells

Quiescent prostate cancer (PCa) cells are common in tumors but are often resistant to chemotherapy. Quiescent PCa cells are also enriched for a stem-like tumor initiating population, and can lead to recurrence after dormancy. Unfortunately, quiescent PCa cells are difficult to identify and / or target with treatment in part because the relevant markers are intracellular and regulated by protein stability. We addressed this problem by utilizing PCa cells expressing fluorescent markers for CDKN1B (p27) and CDT1, which can separate viable PCa cells into G0, G1, or combined S/G2/M populations. We used FACS to collect G1 and G0 PC3 PCa cells, isolated membrane proteins, and analyzed protein abundance in G0 vs G1 cells by gas chromatography mass spectrometry. Enrichment analysis identified nucleocytoplasmic transport as the most significantly different pathway. To identify cell surface proteins potentially identifying quiescent PCa cells for future patient samples or for antibody based therapeutic research, we focused on differentially abundant plasma membrane proteins, and identified ERBB2 (HER2) as a cell surface protein enriched on G0 PCa cells. High HER2 on the cell membrane is associated with quiescence in PCa cells and likely induced by the bone microenvironment. Using a drug conjugated anti-HER2 antibody (trastuzumab emtansine) in a mouse PCa xenograft model delayed metastatic tumor growth, suggesting approaches that target HER2-high cells may be beneficial in treating PCa. We propose that HER2 is deserving of further study in PCa as a target on quiescent cells to prevent recurrence, decrease chemotherapy resistance, or eradicate minimal residual disease.

Spacecraft sample collection and subsurface excavation of asteroid (101955) Bennu

Carbonaceous asteroids, such as (101955) Bennu, preserve material from the early Solar System, including volatile compounds and organic molecules. We report spacecraft imaging and spectral data collected during and after retrieval of a sample from Bennu’s surface. The sampling event mobilized rocks and dust into a debris plume, excavating a 9-m-long elliptical crater. This exposed material that is darker, spectrally redder, and more abundant in fine particulates than the original surface. The bulk density of the displaced subsurface material was 500–700 kg per cubic meter, about half that of the whole asteroid. Particulates that landed on instrument optics spectrally resemble aqueously altered carbonaceous meteorites. The spacecraft stored 250 ± 101 g of material, which will be delivered to Earth in 2023.

Pebbles and sand on asteroid (162173) Ryugu: In situ observation and particles returned to Earth

The Hayabusa2 spacecraft investigated the C-type (carbonaceous) asteroid (162173) Ryugu. The mission performed two landing operations to collect samples of surface and subsurface material, the latter exposed by an artificial impact. We present images of the second touchdown site, finding that ejecta from the impact crater was present at the sample location. Surface pebbles at both landing sites show morphological variations ranging from rugged to smooth, similar to Ryugu's boulders, and shapes from quasi-spherical to flattened. The samples were returned to Earth on 6 December 2020. We describe the morphology of >5 grams of returned pebbles and sand. Their diverse color, shape, and structure are consistent with the observed materials of Ryugu; we conclude that they are a representative sample of the asteroid.

Monitoring Spontaneous Quiescence and Asynchronous Proliferation-Quiescence Decisions in Prostate Cancer Cells

The proliferation-quiescence decision is a dynamic process that remains incompletely understood. Live-cell imaging with fluorescent cell cycle sensors now allows us to visualize the dynamics of cell cycle transitions and has revealed that proliferation-quiescence decisions can be highly heterogeneous, even among clonal cell lines in culture. Under normal culture conditions, cells often spontaneously enter non-cycling G0 states of varying duration and depth. This also occurs in cancer cells and G0 entry in tumors may underlie tumor dormancy and issues with cancer recurrence. Here we show that a cell cycle indicator previously shown to indicate G0 upon serum starvation, mVenus-p27K-, can also be used to monitor spontaneous quiescence in untransformed and cancer cell lines. We find that the duration of spontaneous quiescence in untransformed and cancer cells is heterogeneous and that a portion of this heterogeneity results from asynchronous proliferation-quiescence decisions in pairs of daughters after mitosis, where one daughter cell enters or remains in temporary quiescence while the other does not. We find that cancer dormancy signals influence both entry into quiescence and asynchronous proliferation-quiescence decisions after mitosis. Finally, we show that spontaneously quiescent prostate cancer cells exhibit altered expression of components of the Hippo pathway and are enriched for the stem cell markers CD133 and CD44. This suggests a hypothesis that dormancy signals could promote cancer recurrence by increasing the proportion of quiescent tumor cells poised for cell cycle re-entry with stem cell characteristics in cancer.

P–193 First cleavage division perpendicular to the pronuclear axis adversely affects the clinical outcome in human embryos

Study question

Does the direction of formation for the first cleavage plane relative to the pronuclear axis affect clinical outcome?

Summary answer

A first cleavage division perpendicular to the pronuclear axis adversely affects the rate of embryo utilization for transfer or cryopreservation and the pregnancy outcome.

What is known already

It remains unclear how the first cleavage plane is determined in human embryos. By using time-lapse monitoring, our previous study (presented in ESHRE 2019) suggested that both the axis and locations of male and female pronuclei are involved in determining the first embryonic cleavage plane. Furthermore, by using immunofluorescence analysis, it was also revealed that most analyzed zygotes showed two pericentrin signals aligned around the interface between the male and female pronuclei. Our findings suggest that the pronuclear axis strongly influences the positions of the centrosomes, which become mitotic spindle poles and define the first cleavage plane. Study design, size, duration: From January 2015 to December 2017, time-lapse imaging (EmbryoScope®) of 3397 intracytoplasmic sperm injection (ICSI) oocytes was conducted. Of those, the relationship between the pronuclear axis and the first cleavage plane was analyzed in 607 normally fertilized embryos that cleaved to two cells and were obtained in 2015. Furthermore, of 3397 ICSI oocytes, 749 transferred embryos were classified based on the first cleavage patterns relative to the pronuclear axis, and the pregnancy rate was examined.

Participants/materials, setting, methods

A straight line connecting the centers of the pronuclei was defined as the 2PN axis. Based on the direction of the first cleavage relative to the 2PN axis, embryos were classified into three groups: parallel, perpendicular and intermediate. Fresh embryos were transferred on Day 2/3 (fresh-ET). Frozen and thawed embryos were transferred on Day 2/3 or Day 5 (F/T-ET). Clinical pregnancy was defined as confirmed gestational sac in the uterine cavity.

Main results and the role of chance

Of 607 analyzed embryos, 506 produced suitable images and were assigned to one of three groups: parallel (84.4%, n = 427), perpendicular (9.7%, n = 49) and intermediate (5.9%, n = 30). Embryos that formed a cleavage furrow parallel to the 2PN axis were significantly more frequent than others (perpendicular, intermediate) (P < 0.001). The embryo utilization rate for transfer or cryopreservation was significantly lower in the perpendicular group than in the parallel group (30.7% vs. 69.3%, P < 0.01). Furthermore, of 749 transferred embryos, 504 assigned to the parallel and perpendicular groups were selected (n = 470 and n = 34, respectively), and the pregnancy outcome was analyzed. The mean maternal age was not significantly different between groups. The pregnancy rate of embryos was 24.2% (n = 45/186) from fresh-ET and 39.4% (n = 112/284) from F/T-ET in the parallel group, and 0% (n = 0/14) from fresh-ET and 15.0% (n = 3/20) from F/T-ET in the perpendicular group. Regardless of the types of embryo transfer (fresh or F/T), the pregnancy rate was significantly lower in the perpendicular group than in the parallel group (P < 0.01). In addition, one of three patients who became pregnant from the transfer of an embryo in the perpendicular group had a miscarriage.

Limitations, reasons for caution

Since only ICSI embryos were analyzed in this study, the influence of fertilization methods on subsequent development could not be investigated. Further studies including preimplantation genetic testing for aneuploidy may help determine the reasons why pregnancy rates differ between groups.

Wider implications of the findings: We suggest that the 2PN axis is essential for determining the first cleavage plane because it seems to be involved in positioning the mitotic spindle poles. The direction of the first cleavage plane relative to the 2PN axis can be an important indicator for predicting embryo development and pregnancy outcome

Trial registration number

none

P–215 The degree of perivitelline space (PS) at the pronuclear stage affects subsequent embryonic development in human zygotes

Study question

Was embryonic development affected by the degree of perivitelline space (PS) at the pronuclear stage in human zygotes?

Summary answer

Zygotes with a fully surrounding PS showed less cytoplasmic fragmentation and a higher blastocyst development rate (BDR) than zygotes with a partially surrounding PS.

What is known already

We previously used abnormally-fertilized oocytes (zygotes with three pronuclei; 3PN), donated by ART patients in our clinic who gave written consent for the research. The zona pellucida (ZP) was artificially removed from these oocytes at the pronuclear stage, termed ZP-free culture. The resultant ZP-free 3PN embryos showed less cytoplasmic fragmentation and a higher rate of good-quality embryos (GQE) compared with ZP-intact embryos. Furthermore, in our clinical setting, the rate of GQE and BDR of normally-fertilized embryos were clearly improved by ZP-free culture in patients with recurrent failure of ART treatments due to severe cytoplasmic fragmentation at the early cleavage stage.

Study design, size, duration

This study included 49 patients who gave written informed consent for our study and were treated with ART in our clinic between March and December 2020. Embryonic development was compared between zygotes with a fully surrounding PS [PS(+)] with those with a partially surrounding PS [PS(-)] at the pronuclear stage. Furthermore, the ZP of PS(-) embryos were artificially removed at the pronuclear stage, and the rate of GQE and BDR were compared with ZP-intact embryos.

Participants/materials, setting, methods

The degree of PS in 128 zygotes was confirmed by hypertonic preparation using 0.125M sucrose-containing HEPES medium. PS(+) and PS(-) embryos were both cultured as ZP-intact, and the rate of GQE was compared. Furthermore, 223 zygotes were divided into three groups: 1) PS(-)/ZP-intact, 2) PS(-)/ZP-free, and 3) PS(+)/ZP-intact, and cultured in an incubator equipped with time-lapse monitoring up to Day 7, and the rate of GQE, BDR and useable embryos were compared between each groups.

Main results and the role of chance

The degree of PS was confirmed by a hypertonic preparation (shrinkage of the ooplasm) in 128 normally-fertilized zygotes obtained from 44 cases. There were 86 PS(-) (67.2%) and 42 PS(+) (32.8%) zygotes. The mean maternal age was 35.9 in PS(-) and 40.5 in PS(+) (P < 0.01), and the rate of GQE was significantly higher in PS(+) [64.3% (27/42)] than in PS(-)[38.4% (33/86)] (P < 0.01). In addition, of 223 normally-fertilized zygotes obtained from 41 cases, there were 51 PS(-)/ZP-intact (Group 1), 132 PS(-)/ZP-free (Group 2) and 40 PS(+)/ZP-intact (Group 3) zygotes. The rate of GQE was significantly lower in Group 1 [29.4% (15/51)] compared with Group 2 [59.8% (79/132)] and Group 3 [62.5% (25/40)] (P < 0.01). BDR was also significantly lower in Group 1 [51.3% (10/39)] compared with Group 2 [75.0% (99/132)] and Group 3 [65.0% (13/20) (P < 0.01).

Limitations, reasons for caution

Although the artificial removal of ZP at the pronuclear stage (ZP-free culture) clearly increased the rate of GQE, embryonic development was not improved in all cases. It seems that this procedure is only effective in embryos with a viable ooplasm.

Wider implications of the findings: The degree of PS at the pronuclear stage affects subsequent embryonic development in human zygotes. The artificial removal of ZP at the pronuclear stage (ZP-free culture) helps to suppress fragmentation and leads to an increase in GQE and BDR, and eventually, improves pregnancy rate in cases with severe fragmentation.

Trial registration number

non

P–201 The beneficial effects of ZP-free culture on cytoplasmic fragmentation in human embryos. : An innovative trial using 3PN zygotes

Study question

Is it possible to culture ZP-free embryos to eliminate perivitelline threads, which are known to be involved in generating cytoplasmic fragments at the first cleavage?

Summary answer

ZP-free culturing, an innovative system that decreases the amount of cytoplasmic fragments without disrupting the blastomeres, using incubators with time-lapse imaging.

What is known already

A study in 2017 observed perivitelline threads in more than 50% of cleavage-stage human embryos using time-lapse imaging, and the rate of cytoplasmic fragmentation (at the first cleavage) was significantly decreased in embryos without perivitelline threads (P < 0.001). While it has been proposed that perivitelline threads play an important role in crosslinking the cumulus cells and oocyte during maturation, the mechanism underlying such a role remains unclear. It is also unknown whether the threads still function in mature MII oocytes.

Study design, size, duration

A prospective study was conducted using 2,852 normal (2PN/2PB) embryos from c-IVF/ICSI and 113 abnormal (3PN) embryos obtained from c-IVF between 2017 and 2019. The zona pellucida (ZP) of 71 abnormal embryos was removed at the pronuclear stage (“ZP-free”), and the rest (n = 42) were cultured as “ZP-intact”. Normal and abnormal embryos were cultured for five days in bench-top incubators (MINC, COOK) and an incubator equipped with a time-lapse imaging system.

Participants/materials, setting, methods

Embryos used in this study were donated by 412 couples who underwent c-IVF cycles in our clinic between 2017 and 2019. For ZP removal, 3PN embryos were placed in 0.125M sucrose-containing HEPES media drops to reduce the ooplasm size. Then, ooplasms were completely separated from ZPs by a laser and pipetting. Embryo development and morphology of the three groups (normal, ZP-intact and ZP-free abnormal) were compared based on the degree of cytoplasmic fragmentation.

Main results and the role of chance

The first cleavage occurred in 97.8% (n = 2,790/2,852) of 2PN/2PB, 83.3% (n = 35/42) of ZP-intact 3PN and 97.2% (n = 69/71) of ZP-free 3PN. Normal (2PN/2PB), ZP-intact and ZP-free 3PN embryos were classified into three groups based on the modified Veeck’s criteria thus: <20% fragmented compared to the total volume of cytoplasm at the first cleavage (Grade 1 and 2, Good); 20–39% fragmented (Grade 3, Fair) and ≧40% fragmented (Grade 4, Poor). Of 69 cleaved ZP-free 3PN embryos, 68.1% (n = 47) showed less than 20% fragments which was significantly higher than 2PN/2PB (43.7%, n = 1,218/2,790) and ZP-intact 3PN (45.7%, n = 16/35; P < 0.05). Furthermore, 24.6% (n = 17/69) of ZP-free 3PN embryos showed 20–39% fragments which was significantly lower than 2PN/2PB (45.9%, n = 1,281/2,790; P < 0.05). In addition, 50.7% of ZP-free 3PN embryos (n = 36) developed to the morula stage after the third cleavage, and 29.6% (n = 21) formed blastocoel and became blastocysts. Thus, removing the ZP before the first cleavage did not adversely affect embryo development and decreased the cytoplasmic fragmentation.

Limitations, reasons for caution

Due to ethical and clinical limitations, we only examined abnormally fertilized embryos in this study. Moreover, since the relationship between the perivitelline threads and cytoplasmic fragments is unclear, we plan to conduct molecular biological analysis of the perivitelline threads in further studies.

Wider implications of the findings: This study revealed that ZP is not always necessary after the pronuclear stage because ZP-free embryos studied herein developed normally and maintained cell adhesion well. This innovative culture method might provide the breakthrough needed for patients to improve embryo quality who obtain embryos with severe fragmentation caused by perivitelline threads.

Trial registration number

Not applicable

O-219 Detailed morpho-kinetic analysis of the first cleavage can help in evaluating the viability of direct-cleaved human zygotes

Study question

Why do some direct-cleaved human zygotes still lead to a live birth?

Summary answer

Direct-cleaved zygotes which have undergone the 2-cell stage can lead to a live birth, while zygotes cleaved from 1-cell to ≥ 3-cell do not.

What is known already

In recent years, zygotes that develop from 2-cell to 3-cell within 5 hours after the first cleavage have been evaluated as “direct-cleaved” zygotes, because normal cleavage takes approximately 12 hours to complete. It was reported that their implantation rate was significantly lower than zygotes with normal cleavage pattern, and eliminating direct-cleaved zygotes from transfer could improve the implantation rate. However, some direct-cleaved zygotes at the first cleavage could still lead to a live birth. Few reports have examined the difference between a cleavage from 1-cell to ≥ 3-cell and 2-cell to ≥ 3-cell within 5 hours after the first cleavage.

Study design, size, duration

A retrospective study involving 2,077 cycles of IVF/ICSI between July 2012 and July 2019. A total of 5,991 normally fertilized zygotes (2PN/2PB) were included. Of those, 3,508 were evaluated as usable good/fair quality embryos on Day2/3, and the rest (n = 2,483) were evaluated as poor quality and rejected from transfer or cryopreservation after 7 days of culture. Of 3,508 usable embryos, 884 were selected based on the availability of results of live birth for this study.

Participants/materials, setting, methods

Time-lapse imaging (5 slices along Z-axis every 10 minutes) was performed in EmbryoScopeTM. Zygotes were morphokinetically analyzed in detail and classified into four groups by their cleavage patterns: Group1 (1-cell→2-cell); Group 2 (1-cell→3-cell); Group 3 (1-cell→2-cell→≥3-cell within 5 hours after the first cleavage); and Group 4 (1-cell→2-cell→≥5-cell). The proportion, mean maternal age and live birth rate of each group were examined.

Main results and the role of chance

The proportion of Groups 1-4 was 83.6% (n = 739), 3.8% (n = 34), 5.9% (n = 52), and 6.7% (n = 59), respectively. 0f 884 zygotes examined in this study, the mean maternal age was significantly higher in Group 2 and 4 than in Group 1 (P < 0.05; 37.4±4.9 in Group1, 39.1±5.2 in Group 2, 38.6±6.0 in Group 3, and 38.7±5.1 in Group 4). The rate of confirmed gestational sac was significantly lower in Group 2 and 4 than in Group 1 [P < 0.01; 36.3% (n = 268/739), 0% (n = 0/34), 25.0% (n = 13/52), and 18.6% (n = 11/59) in Groups 1-4, respectively]. Furthermore, the live birth rate was significantly higher in Group 1 than in Groups 2, 3 and 4 [P < 0.01; 28.4% (n = 210/739), 0% (n = 0/34), 13.5% (n = 7/52), and 15.3% (n = 9/59) in Groups 1-4, respectively]. Above all, while zygotes in Group 2 showed no pregnancy and live birth at all, zygotes in Group 3 showed a live birth rate of 13.5%. However, they had a significantly higher miscarriage rate (42.9%, n = 6) compared to zygotes in Group 1 (19.5%, n = 55).

Limitations, reasons for caution

It is very difficult to capture cleavage patterns by routine observations because the timings of developmental events are different between embryos. A time-lapse imaging and culturing system is essential to solve this problem, however, it cannot visualize the distribution of chromosomes, and no chromosomal analysis was conducted in this study.

Wider implications of the findings

This study revealed that zygotes previously classified as “direct-cleaved” and eliminated from transfer included viable zygotes which could lead to a live birth. Therefore, it is crucial to optimize the use of time-lapse imaging of human zygotes in order to precisely evaluate the first cleavage.

Trial registration number

not applicable

P–216 Successful pregnancies and deliveries in patients with a recurrent failure of ART treatments following artificial removal of the zona pellucida (ZP) at the pronuclear stage

Study question

Can a novel embryo culture method that artificially removes the ZP at the pronuclear stage yield successful pregnancy in patients with poor-quality embryos and/or blastocysts?

Summary answer

A blastocyst transfer after ZP-free culture can result in pregnancy for patients who cannot obtain good quality blastocysts from conventional culture methods.

What is known already

Perivitelline threads are been associated with the formation of cytoplasmic fragments. We had previously observed perivitelline threads in the adhesive region between the ooplasm and the ZP at the first cleavage in human embryos. We removed the ZP at the pronuclear stage in 71 abnormally fertilized oocytes (zygotes with three pronuclei), donated after conventional IVF (c-IVF), and termed them ZP-free 3PN. We found ZP-free 3PN embryos could be cultured without losing blastomere adhesions. Furthermore, the rate of good quality embryos was significantly higher in ZP-free 3PN embryos compared with ZP-intact embryos (ZP-intact 2PN/2PB and 3PN embryos; P < 0.05).

Study design, size, duration

This study was conducted in two cases selected among patients who underwent ART treatment in our clinic between 2018 and 2019. Cases were selected if they lacked good quality blastocysts in previous c-IVF/Intracytoplasmic Sperm Injection (ICSI) cycles due to massive cytoplasmic fragmentation at the first and second cleavage. We performed a clinical trial of ZP-free culture from December 2019 to March 2020.

Participants/materials, setting, methods

Two cases were selected for this trial. Normally fertilized oocytes were grouped as ZP-free or ZP-intact. For the ZP-free group, 2PN embryos were placed in 0.125M sucrose-containing HEPES to reduce ooplasm size, then ooplasms were completely separated from ZPs by a laser and pipetting. ZP-free and ZP-intact embryos were cultured with time-lapse imaging for up to seven days. Resultant blastocysts were either transferred into uterus or cryopreserved on Day5/6/7 for future embryo transfer cycles.

Main results and the role of chance

The ZP-free culture method was applied to two patients (patient A and B) with recurrent failure of ART in our clinic due to poor-quality embryos and/or difficulties in obtaining good quality blastocysts. In both cases, blastocysts were successfully obtained and cryopreserved for all ZP-free culture cycles. In patient A, one good quality ZP-free blastocyst was freshly transferred five days after oocyte retrieval, and a live male baby (2925g) was delivered at 40 weeks of gestation by caesarean section). In patient B, a frozen/thawed ZP-free blastocyst transfer was conducted, and a live female baby (3225g) was delivered at 39 weeks of gestation by vaginal delivery. This shows ZP-free culturing may help obtain viable embryos in patients for which conventional in vitro culturing methods result in embryos characterized with severe cytoplasmic fragmentation and poor quality in the early cleavage stage.

Limitations, reasons for caution

Although successful pregnancies and deliveries were confirmed in two cases, postnatal evaluations will be absolutely necessary for infants derived from ZP-free culture. In addition, the number of trial cases needs to be expanded, however careful selection of suitable patients is necessary for this novel culture method.

Wider implications of the findings: We found removing the ZP at the pronuclear stage improved embryo development and led to successful pregnancies and deliveries after blastocyst transfer. This indicates ZP-free culturing may be an effective method for decreasing cytoplasmic fragmentation caused by perivitelline threads or adhesion between the ooplasm and the zona pellucida.

Trial registration number

Not applicable

Abscisic acid regulates dormancy of prostate cancer disseminated tumor cells in the bone marrow

Prostate cancer (PCa) commonly metastasizes to the bone where the cells frequently undergo dormancy. The escape of disseminated tumor cells from cellular dormancy is a major cause of recurrence in marrow. Abscisic acid (ABA), a phytohormone, is known to regulate dormancy of plant seeds and to regulate other stress responses in plants. Recently, ABA was found to be synthesized by mammals cells and has been linked to human disease. Yet the role of ABA in regulating tumor dormancy or reactivation is unknown. We found that ABA is produced by human marrow cells, and exogenous ABA inhibits PCa cell proliferation while increasing the expression of p27, p21, and p16 and decreasing the expression of the proliferation marker, Ki67. Further, ABA significantly increased the percentage of PCa cells in the G₀ phase of the cell cycle as well as the duration the cells were arrested in G₀. We found that ABA regulates an increase of PPARγ receptor expression and suppressed phosphorylation of mTOR/p70S6K signaling and resulting in the induction of the cellular dormancy. We then confirmed that ABA regulates G₀ cell cycle arrest through PPARγ receptor signaling in vitro and under co-culture conditions with osteoblasts. Finally, we demonstrate that ABA regulates PCa dormancy in vivo following intratibial injection in an animal model. Together these data suggest that the ABA and PPARγ signaling pathways contribute to the establishment of PCa cellular dormancy in the bone marrow microenvironment. These findings may suggest critical pathways for targeting metastatic disease.

Variations in color and reflectance on the surface of asteroid (101955) Bennu

Visible-wavelength color and reflectance provide information about the geologic history of planetary surfaces. Here we present multispectral images (0.44 to 0.89 micrometers) of near-Earth asteroid (101955) Bennu. The surface has variable colors overlain on a moderately blue global terrain. Two primary boulder types are distinguishable by their reflectance and texture. Space weathering of Bennu surface materials does not simply progress from red to blue (or vice versa). Instead, freshly exposed, redder surfaces initially brighten in the near-ultraviolet region (i.e., become bluer at shorter wavelengths), then brighten in the visible to near-infrared region, leading to Bennu's moderately blue average color. Craters indicate that the time scale of these color changes is ~10⁵ years. We attribute the reflectance and color variation to a combination of primordial heterogeneity and varying exposure ages.

Detection and isolation of disseminated tumor cells in bone marrow of patients with clinically localized prostate cancer

BACKGROUND

Disseminated tumor cells (DTCs) have been reported in the bone marrow (BM) of patients with localized prostate cancer (PCa). However, the existence of these cells continues to be questioned, and few methods exist for viable DTC isolation. Therefore, we sought to develop novel approaches to identify and, if detected, analyze localized PCa patient DTCs.

METHODS

We used fluorescence-activated cell sorting (FACS) to isolate a putative DTC population, which was negative for CD45, CD235a, alkaline phosphatase, and CD34, and strongly expressed EPCAM. We examined tumor cell content by bulk cell RNA sequencing (RNA-Seq) and whole-exome sequencing after whole genome amplification. We also enriched for BM DTCs with α-EPCAM immunomagnetic beads and performed quantitative reverse trancriptase polymerase chain reaction (qRT-PCR) for PCa markers.

RESULTS

At a threshold of 4 cells per million BM cells, the putative DTC population was present in 10 of 58 patients (17%) with localized PCa, 4 of 8 patients with metastatic PCa of varying disease control, and 1 of 8 patients with no known cancer, and was positively correlated with patients' plasma PSA values. RNA-Seq analysis of the putative DTC population collected from samples above (3 patients) and below (5 patients) the threshold of 4 putative DTCs per million showed increased expression of PCa marker genes in 4 of 8 patients with localized PCa, but not the one normal donor who had the putative DTC population present. Whole-exome sequencing also showed the presence of single nucleotide polymorphisms and structural variants in the gene characteristics of PCa in 2 of 3 localized PCa patients. To examine the likely contaminating cell types, we used a myeloid colony formation assay, differential counts of cell smears, and analysis of the RNA-Seq data using the CIBERSORT algorithm, which most strongly suggested the presence of B-cell lineages as a contaminant. Finally, we used EPCAM enrichment and qRT-PCR for PCa markers to estimate DTC prevalence and found evidence of DTCs in 21 of 44 samples (47%).

CONCLUSION

These data support the presence of DTCs in the BM of a subset of patients with localized PCa and describe a novel FACS method for isolation and analysis of viable DTCs.

Trim33 is required for appropriate development of pre-cardiogenic mesoderm

Congenital cardiac malformations are among the most common birth defects in humans. Here we show that Trim33, a member of the Tif1 subfamily of tripartite domain containing transcriptional cofactors, is required for appropriate differentiation of the pre-cardiogenic mesoderm during a narrow time window in late gastrulation. While mesoderm-specific Trim33 mutants did not display noticeable phenotypes, epiblast-specific Trim33 mutant embryos developed ventricular septal defects, showed sparse trabeculation and abnormally thin compact myocardium, and died as a result of cardiac failure during late gestation. Differentiating embryoid bodies deficient in Trim33 showed an enrichment of gene sets associated with cardiac differentiation and contractility, while the total number of cardiac precursor cells was reduced. Concordantly, cardiac progenitor cell proliferation was reduced in Trim33-deficient embryos. ChIP-Seq performed using antibodies against Trim33 in differentiating embryoid bodies revealed more than 4000 peaks, which were significantly enriched close to genes implicated in stem cell maintenance and mesoderm development. Nearly half of the Trim33 peaks overlapped with binding sites of the Ctcf insulator protein. Our results suggest that Trim33 is required for appropriate differentiation of precardiogenic mesoderm during late gastrulation and that it will likely mediate some of its functions via multi-protein complexes, many of which include the chromatin architectural and insulator protein Ctcf.

Anticancer polymers designed for killing dormant prostate cancer cells

The discovery of anticancer therapeutics effective in eliminating dormant cells is a significant challenge in cancer biology. Here, we describe new synthetic polymer-based anticancer agents that mimic the mode of action of anticancer peptides. These anticancer polymers developed here are designed to capture the cationic, amphiphilic traits of anticancer peptides. The anticancer polymers are designed to target anionic lipids exposed on the cancer cell surfaces and act by disrupting the cancer cell membranes. Because the polymer mechanism is not dependent on cell proliferation, we hypothesized that the polymers were active against dormant cancer cells. The polymers exhibited cytotoxicity to proliferating prostate cancer. Importantly, the polymer killed dormant prostate cancer cells that were resistant to docetaxel. This study demonstrates a new approach to discover novel anticancer therapeutics.

CXCL12γ Promotes Metastatic Castration-Resistant Prostate Cancer by Inducing Cancer Stem Cell and Neuroendocrine Phenotypes

There is evidence that cancer stem-like cells (CSC) and neuroendocrine behavior play critical roles in the pathogenesis and clinical course of metastatic castration-resistant prostate cancer (m-CRPC). However, there is limited mechanistic understanding of how CSC and neuroendocrine phenotypes impact the development of m-CRPC. In this study, we explored the role of the intracellular chemokine CXCL12γ in CSC induction and neuroendocrine differentiation and its impact on m-CRPC. CXCL12γ expression was detected in small-cell carcinoma of metastatic tissues and circulating tumor cells from m-CRPC patients and in prostate cancer cells displaying an neuroendocrine phenotype. Mechanistic investigations demonstrated that overexpression of CXCL12γ induced CSC and neuroendocrine phenotypes in prostate cancer cells through CXCR4-mediated PKCα/NFκB signaling, which promoted prostate tumor outgrowth, metastasis, and chemoresistance in vivo Together, our results establish a significant function for CXCL12γ in m-CRPC development and suggest it as a candidate therapeutic target to control aggressive disease.Significance: Expression of CXCL12γ induces the expression of a cancer stem cell and neuroendocrine phenotypes, resulting in the development of aggressive m-CRPC. Cancer Res; 78(8); 2026-39. ©2018 AACR.

The marrow niche controls the cancer stem cell phenotype of disseminated prostate cancer

Dissemination of cancer stem cells (CSCs) serves as the basis of metastasis. Recently, we demonstrated that circulating prostate cancer targets the hematopoietic stem cell (HSCs) ‘niche’ in marrow during dissemination. Once in the niche, disseminated tumor cells (DTCs) may remain dormant for extended periods. As the major function of the HSC niche is to maintain stem cell functions, we hypothesized that the niche regulates CSC activities of DTCs. Here we show that DTCs recovered from marrow were significantly enriched for a CSC phenotype. Critically, the conversion of DTCs to CSCs is regulated by niche-derived GAS6 through the Mer/mTOR; molecules previously shown to regulate dormancy. The data demonstrate that the niche plays a significant role in maintaining tumor-initiating prostate cancer in marrow and suggests a functional relationship between CSCs and dormancy. Understanding how the marrow niche regulates the conversion of DTCs to CSCs is critical for the development of therapeutics specifically targeting skeletal bone metastasis and dormancy.

Endogenous GAS6 and Mer receptor signaling regulate prostate cancer stem cells in bone marrow

GAS6 and its receptors (Tryo 3, Axl, Mer or “TAM”) are known to play a role in regulating tumor progression in a number of settings. Previously we have demonstrated that GAS6 signaling regulates invasion, proliferation, chemotherapy-induced apoptosis of prostate cancer (PCa) cells. We have also demonstrated that GAS6 secreted from osteoblasts in the bone marrow environment plays a critical role in establishing prostate tumor cell dormancy. Here we investigated the role that endogenous GAS6 and Mer receptor signaling plays in establishing prostate cancer stem cells in the bone marrow microenvironment.

We first observed that high levels of endogenous GAS6 are expressed by disseminated tumor cells (DTCs) in the bone marrow, whereas relatively low levels of endogenous GAS6 are expressed in PCa tumors grown in a s.c. setting. Interestingly, elevated levels of endogenous GAS6 were identified in putative cancer stem cells (CSCs, CD133+/CD44+) compared to non-CSCs (CD133–/CD44–) isolated from PCa/osteoblast cocultures in vitro and in DTCs isolated from the bone marrow 24 hours after intracardiac injection. Moreover, we found that endogenous GAS6 expression is associated with Mer receptor expression in growth arrested (G₁) PCa cells, which correlates with the increase of the CSC populations. Importantly, we found that overexpression of GAS6 activates phosphorylation of Mer receptor signaling and subsequent induction of the CSC phenotype in vitro and in vivo.

Together these data suggest that endogenous GAS6 and Mer receptor signaling contribute to the establishment of PCa CSCs in the bone marrow microenvironment, which may have important implications for targeting metastatic disease.

Sympathetic Signaling Reactivates Quiescent Disseminated Prostate Cancer Cells in the Bone Marrow

Clinical observations have identified an association between psychologic stress and cancer relapse, suggesting that the sympathetic nervous system/norepinephrine (NE) plays a role in reactivation of dormant disseminated tumor cells (DTC) in the bone marrow niche. Here, the mechanism by which NE regulates prostate cancer DTCs in the marrow is explored. NE directly stimulated prostate cancer cell proliferation through β2-adrenergic receptors (ADRB2). NE also altered prostate cancer proliferation in the marrow niche by indirectly downregulating the secretion of the dormancy inducing molecule growth arrest specific-6 (GAS6) expressed by osteoblasts. These observations were confirmed in cocultures of prostate cancer cells expressing the fluorescent ubiquitination-based cell-cycle reporters (FUCCI) and osteoblasts isolated from GAS6-deficient (GAS6^-/-) animals. A novel ex vivo model system, using femurs harvested from GAS6^+/+ or GAS6^-/- mice, was used to confirm these results. As in coculture, when prostate cancer cells were injected into the marrow cavities of GAS6^+/+ femurs, NE altered the prostate cancer cell cycle. However, NE had less of an impact on prostate cancer cells in femur explants isolated from GAS6^-/- mice. Together, this study demonstrates that NE reactivates prostate cancer cell cycling through both a direct action on prostate cancer cells and indirectly on adjacent niche cells.Implications: Identification of mechanisms that target DTCs may provide novel therapeutic approaches to prevent or treat cancer metastases more effectively. Mol Cancer Res; 15(12); 1644-55. ©2017 AACR.

DNMT1 Regulates Epithelial-Mesenchymal Transition and Cancer Stem Cells, Which Promotes Prostate Cancer Metastasis

Cancer metastasis is a multistep process associated with the induction of an epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs). Although significant progress has been made in understanding the molecular mechanisms regulating EMT and the CSC phenotype, little is known of how these processes are regulated by epigenetics. Here we demonstrate that reduced expression of DNA methyltransferase 1 (DNMT1) plays an important role in the induction of EMT and the CSC phenotype by prostate cancer (PCa) cells, with enhanced tumorigenesis and metastasis. First, we observed that reduction of DNMT1 by 5-azacitidine (5-Aza) promotes EMT induction as well as CSCs and sphere formation in vitro. Reduced expression of DNMT1 significantly increased PCa migratory potential. We showed that the increase of EMT and CSC activities by reduction of DNMT1 is associated with the increase of protein kinase C. Furthermore, we confirmed that silencing DNMT1 is correlated with enhancement of the induction of EMT and the CSC phenotype in PCa cells. Additionally, chromatin immunoprecipitation assay reveals that reduction of DNMT1 promotes the suppression of H3K9me3 and H3K27me3 on the Zeb2 and KLF4 promoter region in PCa cells. Critically, we found in an animal model that significant tumor growth and more disseminated tumor cells in most osseous tissues were observed following injection of 5-Aza pretreated-PCa cells compared with vehicle-pretreated PCa cells. Our results suggest that epigenetic alteration of histone demethylation regulated by reduction of DNMT1 may control induction of EMT and the CSC phenotype, which facilitates tumorigenesis in PCa cells and has important therapeutic implications in targeting epigenetic regulation.

Growth Arrest-Specific 6 (GAS6) Promotes Prostate Cancer Survival by G1 Arrest/S Phase Delay and Inhibition of Apoptosis During Chemotherapy in Bone Marrow

Prostate cancer (PCa) is known to develop resistance to chemotherapy. Growth arrest-specific 6 (GAS6), plays a role in tumor progression by regulating growth in many cancers. Here, we explored how GAS6 regulates the cell cycle and apoptosis of PCa cells in response to chemotherapy. We found that GAS6 is sufficient to significantly increase the fraction of cells in G1 and the duration of phase in PCa cells. Importantly, the effect of GAS6 on G1 is potentiated during docetaxel chemotherapy. GAS6 altered the levels of several key cell cycle regulators, including the downregulation of Cyclin B1 (G2 /M phase), CDC25A, Cyclin E1, and CDK2 (S phase entry), while the upregulation of cell cycle inhibitors p27 and p21, Cyclin D1, and CDK4. Importantly, these changes became further accentuated during docetaxel treatment in the presence of GAS6. Moreover, GAS6 alters the apoptotic response of PCa cells during docetaxel chemotherapy. Docetaxel induced PCa cell apoptosis is efficiently suppressed in PCa cell culture in the presence of GAS6 or GAS6 secreted from co-cultured osteoblasts. Similarly, the GAS6-expressing bone environment protects PCa cells from apoptosis within primary tumors in vivo studies. Docetaxel induced significant levels of Caspase-3 and PARP cleavage in PCa cells, while GAS6 protected PCa cells from docetaxel-induced apoptotic signaling. Together, these data suggest that GAS6, expressed by osteoblasts in the bone marrow, plays a significant role in the regulation of PCa cell survival during chemotherapy, which will have important implications for targeting metastatic disease. J. Cell. Biochem. 117: 2815-2824, 2016. © 2016 Wiley Periodicals, Inc.

Mer Tyrosine Kinase Regulates Disseminated Prostate Cancer Cellular Dormancy

Many prostate cancer (PCa) recurrences are thought to be due to reactivation of disseminated tumor cells (DTCs). We previously found a role of the TAM family of receptor tyrosine kinases TYRO3, AXL, and MERTK in PCa dormancy regulation. However, the mechanism and contributions of the individual TAM receptors is largely unknown. Knockdown of MERTK, but not AXL or TYRO3 by shRNA in PCa cells induced a decreased ratio of P-Erk1/2 to P-p38, increased expression of p27, NR2F1, SOX2, and NANOG, induced higher levels of histone H3K9me3 and H3K27me3, and induced a G1/G0 arrest, all of which are associated with dormancy. Similar effects were also observed with siRNA. Most importantly, knockdown of MERTK in PCa cells increased metastasis free survival in an intra-cardiac injection mouse xenograft model. MERTK knockdown also failed to inhibit PCa growth in vitro and subcutaneous growth in vivo, which suggests that MERTK has specificity for dormancy regulation or requires a signal from the PCa microenvironment. The effects of MERTK on the cell cycle and histone methylation were reversed by p38 inhibitor SB203580, which indicates the importance of MAP kinases for MERTK dormancy regulation. Overall, this study shows that MERTK stimulates PCa dormancy escape through a MAP kinase dependent mechanism, also involving p27, pluripotency transcription factors, and histone methylation. J. Cell. Biochem. 118: 891-902, 2017. © 2016 Wiley Periodicals, Inc.

Tak1, Smad4 and Trim33 redundantly mediate TGF-β3 signaling during palate development

Transforming growth factor-beta3 (TGF-β3) plays a critical role in palatal epithelial cells by inducing palatal epithelial fusion, failure of which results in cleft palate, one of the most common birth defects in humans. Recent studies have shown that Smad-dependent and Smad-independent pathways work redundantly to transduce TGF-β3 signaling in palatal epithelial cells. However, detailed mechanisms by which this signaling is mediated still remain to be elucidated. Here we show that TGF-β activated kinase-1 (Tak1) and Smad4 interact genetically in palatal epithelial fusion. While simultaneous abrogation of both Tak1 and Smad4 in palatal epithelial cells resulted in characteristic defects in the anterior and posterior secondary palate, these phenotypes were less severe than those seen in the corresponding Tgfb3 mutants. Moreover, our results demonstrate that Trim33, a novel chromatin reader and regulator of TGF-β signaling, cooperates with Smad4 during palatogenesis. Unlike the epithelium-specific Smad4 mutants, epithelium-specific Tak1:Smad4- and Trim33:Smad4-double mutants display reduced expression of Mmp13 in palatal medial edge epithelial cells, suggesting that both of these redundant mechanisms are required for appropriate TGF-β signal transduction. Moreover, we show that inactivation of Tak1 in Trim33:Smad4 double conditional knockouts leads to the palatal phenotypes which are identical to those seen in epithelium-specific Tgfb3 mutants. To conclude, our data reveal added complexity in TGF-β signaling during palatogenesis and demonstrate that functionally redundant pathways involving Smad4, Tak1 and Trim33 regulate palatal epithelial fusion.

Annexin 2-CXCL12 interactions regulate metastatic cell targeting and growth in the bone marrow

Annexin 2 (ANXA2) plays a critical role in hematopoietic stem cell (HSC) localization to the marrow niche. In part, ANXA2 supports HSCs by serving as an anchor for stromal-derived factor-1 (CXCL12/SDF-1). Recently, it was demonstrated that prostate cancer cells, like HSCs, use ANXA2 to establish metastases in marrow. The present study determined the capacity of ANXA2 expression by bone marrow stromal cells (BMSC) to facilitate tumor recruitment and growth through ANXA2-CXCL12 interactions. Significantly more CXCL12 was expressed by BMSC(Anxa2) (+/+) than by BMSC(Anxa2) (-/-) resulting in more prostate cancer cells migrating and binding to BMSC(Anxa2) (+/+) than BMSC(Anxa2) (-/-), and these activities were reduced when CXCL12 interactions were blocked. To further confirm that BMSC signaling through ANXA2-CXCL12 plays a critical role in tumor growth, immunocompromised SCID mice were subcutaneously implanted with human prostate cancer cells mixed with BMSC(Anxa2) (+/+) or BMSC(Anxa2) (-/-). Significantly larger tumors grew in the mice when the tumors were established with BMSC(Anxa2) (+/+) compared with the tumors established with BMSC(Anxa2) (-/-). In addition, fewer prostate cancer cells underwent apoptosis when cocultured with BMSC(Anxa2) (+/+) compared with BMSC(Anxa2) (-/-), and similar results were obtained in tumors grown in vivo. Finally, significantly more vascular structures were observed in the tumors established with the BMSC(Anxa2) (+/+) compared with the tumors established with BMSC(Anxa2) (-/-). Thus, ANXA2-CXCL12 interactions play a crucial role in the recruitment, growth, and survival of prostate cancer cells in the marrow.

IMPLICATIONS

The tumor microenvironment interaction between ANXA2-CXCL12 is critical for metastatic phenotypes and may impact chemotherapeutic potential.

Control elements targeting Tgfb3 expression to the palatal epithelium are located intergenically and in introns of the upstream Ift43 gene

Tgfb3 is strongly and specifically expressed in the epithelial tips of pre-fusion palatal shelves where it plays a critical non-redundant role in palatal fusion in both medial edge epithelial (MEE) cells and in a thin layer of flattened peridermal cells that covers the MEE. It is not known how Tgfb3 expression is regulated in these specific cell types. Using comparative genomics and transgenic reporter assays, we have identified cis-regulatory elements that could control Tgfb3 expression during palatogenesis. Our results show that a 61-kb genomic fragment encompassing the Tgfb3 gene drives remarkably specific reporter expression in the MEE and adjacent periderm. Within this fragment, we identified two small, non-coding, evolutionarily conserved regions in intron 2 of the neighboring Ift43 gene, and a larger region in the intervening sequence between the Ift43 and Tgfb3 genes, each of which could target reporter activity to the tips of pre-fusion/fusing palatal shelves. Identification of the cis-regulatory sequences controlling spatio-temporal Tgfb3 expression in palatal shelves is a key step toward understanding upstream regulation of Tgfb3 expression during palatogenesis and should enable the development of improved tools to investigate palatal epithelial fusion.

Molecular pathways: niches in metastatic dormancy

Despite the best available treatments for primary tumors, cancer can return, even after a long disease-free interval. During this period, cancer cells are believed to lie dormant in either primary sites, metastatic sites, or independent sites like bone marrow, effectively escaping adjuvant cytotoxic treatments. To date, little is known about how these cells transition to dormancy, or how they are reactivated if cancer recurs. Recent studies have revealed the effects of tumor microenvironment or niche on the regulation of tumor dormancy via the signaling pathways of growth arrest-specific 6, bone morphogenetic protein 7, and TGFβ1, and that the balance between activation of p38 MAPK and ERK MAPK plays a pivotal role in tumor dormancy. In this review, we discuss tumor dormancy from the perspective of the niche and consider potential therapeutic targets. Greater understanding of the mechanisms involved will help guide innovation in the care of patients with advanced cancer.

Erythropoietin supports the survival of prostate cancer, but not growth and bone metastasis

Erythropoietin (Epo) is used in clinical settings to enhance hematopoietic function and to improve the quality of life for patients undergoing chemotherapy by reducing fatigue and the need for transfusions. However, several meta-analyses have revealed that Epo treatments are associated with an increased risk of mortality in cancer patients. In this study, we examined the role of Epo in prostate cancer (PCa) progression, using in vitro cell culture systems and in vivo bone metastatic assays. We found that Epo did not stimulate the proliferation of PCa cell lines, but did protect PCa cells from apoptosis. In animal models of PCa metastasis, no evidence was found to support the hypothesis that Epo enhances metastasis. Together, these findings suggest that Epo may be useful for treating severe anemia in PCa patients without increasing metastatic risk.

A novel method for monitoring tumor proliferation in vivo using fluorescent dye DiD

Monitoring single cell proliferation in vivo is difficult, but optimizing this technique is essential in order to expand our knowledge of the regulation of tumor proliferation. In this study, we used a lipophilic fluorescent dye, DiD, that rapidly and stably integrates into the phospholipid cell membrane. We cultured DiD-stained prostate cancer cell lines for 10 days and isolated cells by flow cytometry based on expression levels of DiD. We found that a decrease in DiD intensity was correlated to the reduction of EdU, where the DiD-high population proliferated more slowly than the DiD-low population and the DiD-low population exhibited a higher mitotic index. We also found that DiD was detected after 3 weeks of implantation in an in vivo setting. Importantly, DiD dye did not have any effect on normal cell growth, whereas a gold standard fluorescent dye for measuring cell proliferation, CFSE, slowed cell proliferation. Although further study is indicated, DiD can be useful for identifying the molecular mechanisms underlying tumor proliferation in vivo.

GAS6 receptor status is associated with dormancy and bone metastatic tumor formation

Disseminated tumor cells (DTCs) are believed to lie dormant in the marrow before they can be activated to form metastases. How DTCs become dormant in the marrow and how dormant DTCs escape dormancy remains unclear. Recent work has shown that prostate cancer (PCa) cell lines express the growth-arrest specific 6 (GAS6) receptors Axl, Tyro3, and Mer, and become growth arrested in response to GAS6. We therefore hypothesized that GAS6 signaling regulates the proliferative activity of DTCs in the marrow. To explore this possibility, in vivo studies were performed where it was observed that when Tyro3 expression levels exceed Axl expression, the PCa cells exhibit rapid growth. When when Axl levels predominate, PCa cells remain largely quiescent. These findings suggest that a balance between the expression of Axl and Tyro3 is associated with a molecular switch between a dormant and a proliferative phenotype in PCa metastases.

TGF-β-activated kinase 1 (Tak1) mediates agonist-induced Smad activation and linker region phosphorylation in embryonic craniofacial neural crest-derived cells

BACKGROUND

The role of Smad-independent TGF-β signaling in craniofacial development is poorly elucidated.

RESULTS

In craniofacial mesenchymal cells, Tak1 regulates both R-Smad C-terminal and linker region phosphorylation in TGF-β signaling.

CONCLUSION

Tak1 plays an irreplaceable role in craniofacial ecto-mesenchyme during embryogenesis.

SIGNIFICANCE

Understanding the mechanisms of TGF-β signaling contributes to knowledge of pathogenetic mechanisms underlying common craniofacial birth defects. Although the importance of TGF-β superfamily signaling in craniofacial growth and patterning is well established, the precise details of its signaling mechanisms are still poorly understood. This is in part because of the concentration of studies on the role of the Smad-dependent (so-called "canonical") signaling pathways relative to the Smad-independent ones in many biological processes. Here, we have addressed the role of TGF-β-activated kinase 1 (Tak1, Map3k7), one of the key mediators of Smad-independent (noncanonical) TGF-β superfamily signaling in craniofacial development, by deleting Tak1 specifically in the neural crest lineage. Tak1-deficient mutants display a round skull, hypoplastic maxilla and mandible, and cleft palate resulting from a failure of palatal shelves to appropriately elevate and fuse. Our studies show that in neural crest-derived craniofacial ecto-mesenchymal cells, Tak1 is not only required for TGF-β- and bone morphogenetic protein-induced p38 Mapk activation but also plays a role in agonist-induced C-terminal and linker region phosphorylation of the receptor-mediated R-Smads. Specifically, we demonstrate that the agonist-induced linker region phosphorylation of Smad2 at Thr-220, which has been shown to be critical for full transcriptional activity of Smad2, is dependent on Tak1 activity and that in palatal mesenchymal cells TGFβRI and Tak1 kinases mediate both overlapping and distinct TGF-β2-induced transcriptional responses. To summarize, our results suggest that in neural crest-derived ecto-mesenchymal cells, Tak1 provides a critical point of intersection in a complex dialogue between the canonical and noncanonical arms of TGF-β superfamily signaling required for normal craniofacial development.

Successful cessation of transmitting healthcare -- associated infections due to Burkholderia cepacia complex in a neonatal intensive care unit in a Japanese children's hospital

Background

Burkholderia cepacia strains have been known to possess the capability to cause serious infections especially in neonatal intensive care units (NICUs), and their multi-drug resistances become a severe threat in hospital settings. The aim of this investigation was to evaluate the B. cepacia complex infections in the NICU in Nagano Children's Hospital, Azumino 399-8288, Japan, and to report the intervention leading to the successful cessation of the outbreak.

Methodology

The incidence of isolation and antimicrobial susceptibilities of nosocomial Burkholderia cepacia complex strains during a four-year period were retrospectively examined by clinical microbiological records, and by pulsed-field gel electrophoresis analyses along with the bacteriological verification of disinfectant device itself and procedures for its maintenance routinely used in the NICU.

Results

During the period surveyed between 2007 and 2009, only an isolate per respective year of B. cepacia complex was recovered from each neonate in the NICU. However, in 2010, the successive 6 B. cepacia complex isolates were recovered from different hospitalized neonates. Among them, an isolate was originated from peripheral blood of a neonate, apparently giving rise to systemic infection. In addition, the hospitalized neonate with bacteremia due to B. cepacia complex also exhibited positive cultures from repeated catheterized urine samples together with tracheal aspirate secretions. However other 5 isolates were considered as the transients or contaminants having little to do with infections. Moreover, the 5 isolates between July and October in 2010 revealed completely the same electrophoresis patterns by means of pulsed-field gel electrophoresis analyses, strongly indicating that they were infected through the same medical practices, or by transmission of the same contaminant.

Conclusions

A small outbreak due to B. cepacia complex was brought about in the NICU in 2010, which appeared to be associated with the same genomovar of B. cepacia complex. The source or the rout of infection was unknown in spite of the repeated epidemiological investigation. It is noteworthy that no outbreak due to B. cepacia complex was noted in the NICU after extensive surveillance intervention.

Protein array profiling of mouse serum, six months post whole body radiation with (56)Fe

To determine the chronic effects of heavy ion irradiation, an antibody based proteomic microarray technology was applied to monitor alterations in the serum proteome, six months after whole body irradiation of adult male C57Bl/6 mice with 0.5 Gray of (56)Fe. Out of 507 proteins, irradiation reduced expression of 25 proteins and enhanced expression of 12 proteins in serum (> 5% change relative to sham-irradiated controls). Of the 25 proteins found to be down-regulated, Poly ADP Ribose Polymerase (PARP) was 13% lower in the 0.5Gy mice and among the up-regulated proteins, beta-Tubulin was found to be 10% higher in the 0.5Gy group compared to the sham-irradiated 0Gy controls. Thus, irradiation with a relatively low dose of heavy ions caused persistent and selective changes in serum levels of proteins that are typically intracellular, suggesting chronic genotoxic damage.

Osteopontin Deficiency Suppresses Tumor Necrosis Factor-α-Induced Apoptosis in Chondrocytes

OBJECTIVE

Apoptosis of chondrocytes in articular cartilage has been observed in rheumatoid arthritis patients. However, molecules involved in such chondrocyte apoptosis in arthritic joints have not been fully understood. We previously observed that apoptosis of chondrocytes is enhanced in a murine arthritis model induced by injection with anti-type II collagen antibodies and lipopolysaccharide (mAbs/LPS), and osteopontin (OPN) deficiency suppresses chondrocyte apoptosis in this arthritis model in vivo. To understand how OPN deficiency renders resistance against chondrocyte apoptosis, we examined the cellular basis for this protection.

DESIGN

Chondrocytes were prepared from wild-type and OPN-deficient mouse ribs, and tumor necrosis factor (TNF)-α-induced cell death was examined based on lactate dehydrogenase (LDH) release assay and TUNEL assay.

RESULTS

TNF-α treatment induced LDH release in wild-type chondrocytes, while OPN deficiency suppressed such LDH release in the cultures of these cells. TNF-α-induced increase in the number of TUNEL-positive cells was observed in wild-type chondrocytes, while OPN deficiency in chondrocytes suppressed the TNF-α induction of TUNEL-positive cells. OPN deficiency suppressed TNF-α-induced increase in caspase-3 activity in chondrocytes in culture. Furthermore, OPN overexpression in chondrocytes enhanced TNF-α-induced apoptosis.

CONCLUSION

These results indicated that the presence of OPN in chondrocytes is involved in the susceptibility of these cells to TNF-α-induced apoptosis.

Heavy ion irradiation and unloading effects on mouse lumbar vertebral microarchitecture, mechanical properties and tissue stresses

Astronauts are exposed to both musculoskeletal disuse and heavy ion radiation in space. Disuse alters the magnitude and direction of forces placed upon the skeleton causing bone remodeling, while energy deposited by ionizing radiation causes free radical formation and can lead to DNA strand breaks and oxidative damage to tissues. Radiation and disuse each result in a net loss of mineralized tissue in the adult, although the combined effects, subsequent consequences for mechanical properties and potential for recovery may differ. First, we examined how a high dose (2 Gy) of heavy ion radiation ((56)Fe) causes loss of mineralized tissue in the lumbar vertebrae of skeletally mature (4 months old), male, C57BL/6 mice using microcomputed tomography and determined the influence of structural changes on mechanical properties using whole bone compression tests and finite element analyses. Next, we tested if a low dose (0.5 Gy) of heavy particle radiation prevents skeletal recovery from a 14-day period of hindlimb unloading. Irradiation with a high dose of (56)Fe (2 Gy) caused bone loss (-14%) in the cancellous-rich centrum of the fourth lumbar vertebra (L4) 1 month later, increased trabecular stresses (+27%), increased the propensity for trabecular buckling and shifted stresses to the cortex. As expected, hindlimb unloading (14 days) alone adversely affected microarchitectural and mechanical stiffness of lumbar vertebrae, although the reduction in yield force was not statistically significant (-17%). Irradiation with a low dose of (56)Fe (0.5 Gy) did not affect vertebrae in normally loaded mice, but significantly reduced compressive yield force in vertebrae of unloaded mice relative to sham-irradiated controls (-24%). Irradiation did not impair the recovery of trabecular bone volume fraction that occurs after hindlimb unloaded mice are released to ambulate normally, although microarchitectural differences persisted 28 days later (96% increase in ratio of rod- to plate-like trabeculae). In summary, (56)Fe irradiation (0.5 Gy) of unloaded mice contributed to a reduction in compressive strength and partially prevented recovery of cancellous microarchitecture from adaptive responses of lumbar vertebrae to skeletal unloading. Thus, irradiation with heavy ions may accelerate or worsen the loss of skeletal integrity triggered by musculoskeletal disuse.