TASK DEFINITION: In this task, you are given an abstract of article. Your task is to generate title for this article. Preferred titles are under thirty words.
PROBLEM: A long-standing hypothesis on tumorigenesis is that cell division failure, generating genetically unstable tetraploid cells, facilitates the development of aneuploid malignancies. Here we test this idea by transiently blocking cytokinesis in p53-null (p53-/-) mouse mammary epithelial cells (MMECs), enabling the isolation of diploid and tetraploid cultures. The tetraploid cells had an increase in the frequency of whole-chromosome mis-segregation and chromosomal rearrangements. Only the tetraploid cells were transformed in vitro after exposure to a carcinogen. Furthermore, in the absence of carcinogen, only the tetraploid cells gave rise to malignant mammary epithelial cancers when transplanted subcutaneously into nude mice. These tumours all contained numerous non-reciprocal translocations and an 830-fold amplification of a chromosomal region containing a cluster of matrix metalloproteinase (MMP) genes. MMP overexpression is linked to mammary tumours in humans and animal models. Thus, tetraploidy enhances the frequency of chromosomal alterations and promotes tumour development in p53-/- MMECs.

SOLUTION: Cytokinesis failure generating tetraploids promotes tumorigenesis in p53-null cells

PROBLEM: Increasing evidence suggests long non-coding RNAs (lncRNAs) are frequently aberrantly expressed in cancers, however, few related lncRNA signatures have been established for prediction of cancer prognosis. We aimed to develop a lncRNA signature to improve prognosis prediction of colorectal cancer (CRC). Using a lncRNA-mining approach, we performed lncRNA expression profiling in large CRC cohorts from Gene Expression Ominus (GEO), including GSE39582 test series(N=436), internal validation series (N=117); and two independent validation series GSE14333 (N=197) and GSE17536(N=145). We established a set of six lncRNAs that were significantly correlated with the disease free survival (DFS) in the test series. Based on this six-lncRNA signature, the test series patients could be classified into high-risk and low-risk subgroups with significantly different DFS (HR=2.670; P<0.0001). The prognostic value of this six-lncRNA signature was confirmed in the internal validation series and another two independent CRC sets. Gene set enrichment analysis (GSEA) analysis suggested that risk score positively correlated with several cancer metastasis related pathways. Functional experiments demonstrated three dysregulated lncRNAs, AK123657, BX648207 and BX649059 were required for efficient invasion and proliferation suppression in CRC cell lines. Our results might provide an efficient classification tool for clinical prognosis evaluation of CRC.

SOLUTION: A long non-coding RNA signature to improve prognosis prediction of colorectal cancer

PROBLEM: Although haematopoietic stem cells (HSCs) are commonly assumed to reside within a specialized microenvironment, or niche, most published experimental manipulations of the HSC niche have affected the function of diverse restricted progenitors. This raises the fundamental question of whether HSCs and restricted progenitors reside within distinct, specialized niches or whether they share a common niche. Here we assess the physiological sources of the chemokine CXCL12 for HSC and restricted progenitor maintenance. Cxcl12(DsRed) knock-in mice (DsRed-Express2 recombined into the Cxcl12 locus) showed that Cxcl12 was primarily expressed by perivascular stromal cells and, at lower levels, by endothelial cells, osteoblasts and some haematopoietic cells. Conditional deletion of Cxcl12 from haematopoietic cells or nestin-cre-expressing cells had little or no effect on HSCs or restricted progenitors. Deletion of Cxcl12 from endothelial cells depleted HSCs but not myeloerythroid or lymphoid progenitors. Deletion of Cxcl12 from perivascular stromal cells depleted HSCs and certain restricted progenitors and mobilized these cells into circulation. Deletion of Cxcl12 from osteoblasts depleted certain early lymphoid progenitors but not HSCs or myeloerythroid progenitors, and did not mobilize these cells into circulation. Different stem and progenitor cells thus reside in distinct cellular niches in bone marrow: HSCs occupy a perivascular niche and early lymphoid progenitors occupy an endosteal niche.

SOLUTION:
Haematopoietic stem cells and early lymphoid progenitors occupy distinct bone marrow niches