Transcriptome asymmetry within mouse zygotes but not between early embryonic sister blastomeres.

Transcriptome regionalization is an essential polarity determinant among metazoans, directing embryonic axis formation during normal development. Although conservation of this principle in mammals is assumed, recent evidence is conflicting and it is not known whether transcriptome asymmetries exist within unfertilized mammalian eggs or between the respective cleavage products of early embryonic divisions. We here address this by comparing transcriptome profiles of paired single cells and sub-cellular structures obtained microsurgically from mouse oocytes and totipotent embryos. Paired microsurgical spindle and remnant samples from unfertilized metaphase II oocytes possessed distinguishable profiles. Fertilization produces a totipotent 1-cell embryo (zygote) and associated spindle-enriched second polar body whose paired profiles also differed, reflecting spindle transcript enrichment. However, there was no programmed transcriptome asymmetry between sister cells within 2- or 3-cell embryos. Accordingly, there is transcriptome asymmetry within mouse oocytes, but not between the sister blastomeres of early embryos. This work places constraints on pre-patterning in mammals and provides documentation correlating potency changes and transcriptome partitioning at the single-cell level.

EpCAM-positive disseminated cancer cells in bone marrow impact on survival of early-stage NSCLC patients.

INTRODUCTION: Detection of disseminated cancer cells (DCC) in bone marrow (BM) of patients with early-stage NSCLC has been associated with poor outcome. However, the phenotype, and hence relevant therapy targets, of DCCs in BM are unknown. We therefore compared a classical pan-Cytokeratin (CK) antibody for DCC detection with an anti-EpCAM antibody that may also detect more stem-like cells and tested whether assay positivity impacts on the survival of NSCLC patients. MATERIALS AND METHODS: We prospectively collected BM aspirates from 104 non-metastasized NSCLC patients that underwent potentially curative tumor resection from 2011 to 2016 at the Department of Thoracic Surgery of the University Hospital and Hospital Barmherzige Brüder in Regensburg. DCCs were detected by staining with the pan anti-CK antibody A45-B/B3 and the anti-EpCAM antibody HEA-125. We analyzed the association between detection of DCCs and clinicopathological characteristic and patient outcome. RESULTS: CK + and EpCAM + DCCs were detected in 45.2% and 52.9% of patients, respectively. Correlation between the two markers was low and neither of them was associated with sex, age, histology, T or N classification, resection status, grading or smoking habit. No significant association with tumor specific survival (TSS) and progression-free survival (PFS) was observed in patients with CK + DCCs. In contrast, detection of EpCAM + DCCs significantly correlated with reduced PFS (P = 0.017) and TSS (P = 0.017) and remained an independent prognostic variable for PFS and TSS upon multivariate testing (hazard ratio: 7.506 and 3.551, respectively). Detection of EpCAM + DCCs was the only prognostic marker for PFS. CONCLUSIONS: EpCAM+, but not CK + DCCs in BM predict reduced PFS and TSS. This finding suggests that EpCAM + DCCs in the BM comprise metastatic founder cells necessitating their in-depth molecular analysis for detection of novel therapy targets.

Interleukin-6 trans-signaling is a candidate mechanism to drive progression of human DCCs during clinical latency.

Although thousands of breast cancer cells disseminate and home to bone marrow until primary surgery, usually less than a handful will succeed in establishing manifest metastases months to years later. To identify signals that support survival or outgrowth in patients, we profile rare bone marrow-derived disseminated cancer cells (DCCs) long before manifestation of metastasis and identify IL6/PI3K-signaling as candidate pathway for DCC activation. Surprisingly, and similar to mammary epithelial cells, DCCs lack membranous IL6 receptor expression and mechanistic dissection reveals IL6 trans-signaling to regulate a stem-like state of mammary epithelial cells via gp130. Responsiveness to IL6 trans-signals is found to be niche-dependent as bone marrow stromal and endosteal cells down-regulate gp130 in premalignant mammary epithelial cells as opposed to vascular niche cells. PIK3CA activation renders cells independent from IL6 trans-signaling. Consistent with a bottleneck function of microenvironmental DCC control, we find PIK3CA mutations highly associated with late-stage metastatic cells while being extremely rare in early DCCs. Our data suggest that the initial steps of metastasis formation are often not cancer cell-autonomous, but also depend on microenvironmental signals.