Pre-osteoblastic MC3T3-E1 cells promote breast cancer growth in bone in a murine xenograft model

The bones are the most common sites of breast cancer metastasis. Upon arrival within the bone microenvironment, breast cancer cells coordinate the activities of stromal cells, resulting in an increase in osteoclast activity and bone matrix degradation. In late stages of bone metastasis, breast cancer cells induce apoptosis in osteoblasts, which further exacerbates bone loss. However, in early stages, breast cancer cells induce osteoblasts to secrete inflammatory cytokines purported to drive tumor progression. To more thoroughly evaluate the role of osteoblasts in early stages of breast cancer metastasis to the bones, we used green fluorescent protein-labeled human breast cancer cell lines MDA-MB-231 and MDA-MB-435, which both induce osteolysis after intra-femoral injection in athymic mice, and the murine pre-osteoblastic cell line MC3T3-E1 to modulate osteoblast populations at the sites of breast cancer metastasis. Breast cancer cells were injected directly into the femur with or without equal numbers of MC3T3-E1 cells. Tumors grew significantly larger when co-injected with breast cancer cells and MC3T3-E1 cells than injected with breast cancer cells alone. Osteolysis was induced in both groups, indicating that MC3T3-E1 cells did not block the ability of breast cancer cells to cause bone destruction. MC3T3-E1 cells promoted tumor growth out of the bone into the extraosseous stroma. These data suggest that breast cancer cells and osteoblasts communicate during early stages of bone metastasis and promote tumor growth.

Retrieval and Amplification of DNA from Unstained Histopathological Sections

Testing of compounds for carcinogenic potential in vivo involves various experimental designs. A few of these techniques are directed to demonstrate the genotoxicity and mutagenicity of the compound by histopathology. These changes shown by histochemical means include monoclonal antibody directed cellular markers. Development of the polymerase chain reaction technique (PCR) for amplification of DNA has facilitated the investigation of molecular events related to the formation of malignant neoplasms. We describe here a method for screening tissues for mutations of the H-ras gene using monoclonal antibodies directed toward normal and mutant p21 proteins. Formalin-fixed, paraffin-embedded tissue sections are used to subsequently confirm the gene mutation by PCR amplification of the H-ras gene. The results indicated a successful application of this technique to demonstrate the presence of p21 oncoprotein in the tissues tested.

N6-methyladenosine modified LINC00901 promotes pancreatic cancer progression through IGF2BP2/MYC axis

Accumulating evidence indicates that RNA methylation at N6-methyladenosine(m6A)plays an important regulatory role in gene expression and aberrant mRNA m6A modification is often associated with a variety of cancers.However,little is known whether and how m6A-modification impacts long non-coding RNA(lncRNA)and lncRNA-mediated tumorigenesis,particularly in pancreatic ductal adenocarcinoma(PDAC).In the present study,we report that a previously uncharacterized lncRNA,LINC00901,promotes pancreatic cancer cell growth and invasion and moreover,LINC00901 is subject to m6A modification which regulates its expression.In this regard,YTHDF1 serves as a reader for the m6A modified LINC00901 and downregulates the LINC00901 level.Notably,two conserved m6A sites in LINC00901 are critical to the recognition of LINC00901 by YTHDF1.Finally,RNA sequencing(RNA-seq)and gene function analysis revealed that LINC00901 positively regulates MYC through upregulation of IGF2BP2,a known RNA binding protein that can enhance MYC mRNA stability.Together,our results suggest that there is a LINC00901-IGF2BP2-MYC axis through which LINC00901 promotes PDAC progression in an m6A dependent manner.

Emerging roles of lncRNAs in the post-transcriptional regulation in cancer

Accumulating evidence indicates that long non-coding RNAs(lncRNAs)can play a pivotal role in regulation of diverse cellular processes.In particular,lncRNAs can serve as master gene regulators at transcriptional and posttranscriptional levels,leading to tumorigenesis.In this review,we discuss latest developments in lncRNA-meditated gene expression at the post-transcriptional level,including gene splicing,mRNA stability,protein stability and nuclear trafficking.

Long non-coding RNAs as key regulators of cancer metastasis

The recent advances in functional genomics have discovered that a large number of long non-coding RNAs(lncRNAs)are pervasively transcribed from the human genome.Increasing evidence further indicates that lncRNAs are important for gene expression during cell differentiation and development through various mechanisms such as nuclear organization,post-transcription regulation,alternative splicing,and epigenetic regulation.Thus,aberrant expression of lncRNAs can cause abnormality in those cellular functions and lead to various pathological conditions.One of such fatal consequences is cancer metastasis which is responsible for more than 90%of cancer-related deaths.A good understanding of how lncRNAs regulate different genetic and epigenetic changes during different stages of cancer metastasis is important not only for general cancer biology but also for identification of novel biomarkers and therapeutic targets for treatment of metastatic cancer.A significant progress has been made regarding the role of lncRNAs in cancer for past several years.In this study,we first discuss general functions of lncRNAs and then highlight recent findings of how lncRNAs impact cancer metastasis,and finally we provide our perspectives on clinical implications of lncRNAs.