Genome-wide mRNA and miRNA expression profiling reveal multiple regulatory networks in colorectal cancer

Despite recent advances in cancer management, colorectal cancer (CRC) remains the third most common cancer and a major health-care problem worldwide. MicroRNAs have recently emerged as key regulators of cancer development and progression by targeting multiple cancer-related genes; however, such regulatory networks are not well characterized in CRC. Thus, the aim of this study was to perform global messenger RNA (mRNA) and microRNA expression profiling in the same CRC samples and adjacent normal tissues and to identify potential miRNA-mRNA regulatory networks. Our data revealed 1273 significantly upregulated and 1902 downregulated genes in CRC. Pathway analysis revealed significant enrichment in cell cycle, integrated cancer, Wnt (wingless-type MMTV integration site family member), matrix metalloproteinase, and TGF-β pathways in CRC. Pharmacological inhibition of Wnt (using XAV939 or IWP-2) or TGF-β (using SB-431542) pathways led to dose- and time-dependent inhibition of CRC cell growth. Similarly, our data revealed up- (42) and downregulated (61) microRNAs in the same matched samples. Using target prediction and bioinformatics, ~77% of the upregulated genes were predicted to be targeted by microRNAs found to be downregulated in CRC. We subsequently focused on EZH2 (enhancer of zeste homolog 2 ), which was found to be regulated by hsa-miR-26a-5p and several members of the let-7 (lethal-7) family in CRC. Significant inverse correlation between EZH2 and hsa-miR-26a-5p (R(2)=0.56, P=0.0001) and hsa-let-7b-5p (R(2)=0.19, P=0.02) expression was observed in the same samples, corroborating the belief of EZH2 being a bona fide target for these two miRNAs in CRC. Pharmacological inhibition of EZH2 led to significant reduction in trimethylated histone H3 on lysine 27 (H3K27) methylation, marked reduction in cell proliferation, and migration in vitro. Concordantly, small interfering RNA-mediated knockdown of EZH2 led to similar effects on CRC cell growth in vitro. Therefore, our data have revealed several hundred potential miRNA-mRNA regulatory networks in CRC and suggest targeting relevant networks as potential therapeutic strategy for CRC

Human Serum is as Efficient as Fetal Bovine Serum in Supporting Proliferation and Differentiation of Human Multipotent Stromal (Mesenchymal) Stem Cells In Vitro and In Vivo

Background: Human multipotent stromal (skeletal, mesenchymal) stem cells (hMSC) are employed in an increasing number of clinical trials for tissue regeneration of age-related degenerative diseases. However, routine use of fetal bovine sera (FBS) for their in vitro expansion is not optimal and may pose a health risk for patients. Methods: We carried out a side-by-side comparison of the effects of allogenic pooled human serum (HuS) versus FBS on hMSC proliferation and differentiation in vitro and in vivo. As a model for hMSC, we employed telomerase-immortalized hMSC; hMSC-TERT cell line. Results: hMSC-TERT exhibited similar morphology and size when cultured in HuS vs. FBS as assessed by light microscopy and FACS analysis. We did not observe any significant differences in growth rates of hMSC-TERT during short-term (10 days) and long-term (100 days) culture in media supplemented with HuS vs. FBS. hMSC-TERT or primary bone marrow derived hMSC induced to osteoblastic or adipocytic differentiation in the presence of HuS or FBS showed comparable levels of gene expression and protein production of osteoblastic markers (CBFA1/Runx2, alkaline phosphastase, collagen type I and osteocalcin) or adipocytic markers (PPAR-gamma2, lipoprotein lipase (LPL), aP2), respectively. In order to test for the functional capacity of hMSC-TERT that have been maintained in long-term cultures in the presence of HuS vs. FBS, the cells were mixed with hydroxyapatite/tricalcium phosphate (HA/TCP) and implanted subcutaneously in immune deficient mice. hMSC maintained in HuS vs. FBS formed comparable heterotopic bone. Discussion: Human serum can support proliferation and differentiation of hMSC in vitro and can maintain their bone forming capacity in vivo. The use of human serum in cell cultures of hMSC intended for cell-based therapy is preferable

CD34 defines an osteoprogenitor cell population in mouse bone marrow stromal cells

Bone marrow stromal cells (BMSCs, also known as bone marrow-derived mesenchymal stem cells) and their progenitors have been identified based on retrospective functional criteria. CD markers are employed to define cell populations with distinct functional characteristics. However, defining and prospective isolation of BMSCs and committed progenitors are lacking. Here, we compared the transcriptome profile of CD markers expressed at baseline and during the course of osteoblast and adipocyte differentiation of two well-characterized osteogenic-committed murine BMSCs (mBMSCBone) and adipogenic-committed mBMSCs (mBMSCAdipo), respectively. Bioinformatic analysis revealed the presence of a core set of canonical mBMSC CD markers with comparable expression levels in mBMSCBone and mBMSCAdipo at baseline and during their differentiation. We identified 11 CD markers that are differentially expressed between mBMSCAdipo and mBMSCBone. Among these, we identified osteoprogenitor-associated CD markers expressed only in mBMSCBone: CD34, CD54, CD73, CD132, CD200, CD227 and adipoprogenitor-associated CD markers expressed only in mBMSCAdipo: CD53, CD80, CD134, CD141 and CD212. FACS analysis confirmed these results. We selected CD34 for further analysis. CD34 was expressed at baseline of mouse stromal cell line ST2, primary mBMSCs, mBMSCBone and its expression decreased during osteoblast differentiation. FACS-sorted CD34+ primary mBMSCs exhibited higher expression of 70% osteoblast-associated genes, and formed significantly higher heterotopic bone in vivo when implanted subcutaneously in immune-deficient mice compared with CD34− primary mBMSCs. Our results demonstrate that a set of CD markers can distinguish osteoprogenitor versus adipoprogenitor populations of mBMSCs. CD34 is suitable for prospective isolation of mouse bone marrow osteoprogenitors

Humanized culture of periosteal progenitors in allogeneic serum enhances osteogenic differentiation and in vivo bone formation

The translation of stem cell-based regenerative solutions from the laboratory to the clinic is often hindered by the culture conditions used to expand cell populations. Although fetal bovine serum (FBS) is widely used, regulatory bodies and safety concerns encourage alternative, xeno-free culturing practices. In an attempt to apply this approach to a bone-forming combination product of human periosteal progenitors (human periosteum derived cells) on a clinically used calcium phosphate carrier, FBS was substituted for human allogeneic serum (hAS) during cell expansion. It was found that cell proliferation was increased in hAS along with an apparent commitment to the osteogenic lineage, indicated by enhanced Runx2 expression, as well as alkaline phosphatase activity and matrix mineralization. Following analysis of signaling pathways, it was found that interferon-mediated signaling was downregulated, whereas JAK-STAT signaling was upregulated. STAT3 phosphorylation was enhanced in hAS-cultured human periosteum derived cells, inhibition of which ablated the proliferative effect of hAS. Furthermore, following in vivo implantation of hAS-cultured cells on NuOss scaffolds, enhanced bone formation was observed compared with FBS (71% increase, p < .001). Interestingly, the de novo-formed bone appeared to have a higher ratio of immature regions to mature regions, indicating that after 8 weeks implantation, tissue-formation processes were continuing. Integration of the implant with the environment appeared to be altered, with a decrease in calcium phosphate grain size and surface area, indicative of accelerated resorption. This study highlights the advantages of using humanized culture conditions for the expansion of human periosteal progenitors intended for bone regeneration