Signet-ring cell carcinoma of colorectum : current perspectives and molecular biology

PURPOSE Colorectal signet-ring cell carcinoma (SRCC) is rare, and very little detailed information on the molecular biology of the disease is available. METHODS The literature on the clinical, pathological and, in particular, the molecular biology of this rare entity was critically reviewed. The reviewed articles take into account a total of 1,817 cases of SRCC, but only 143 cases have molecular data available. The characteristics of two patients with colorectal SRCC were also discussed. RESULTS Colorectal SRCC mostly occurs in younger patients, is larger and has different site predilection compared with conventional colorectal adenocarcinoma. It can occur as one of the synchronous cancers in the colorectum. The cancer is usually diagnosed at advanced stages because of the late manifestation of symptoms, and aggressive treatment strategy is required. Limited reports in the literature have shown that the variant of colorectal cancer demonstrated a different pattern of genetic alterations of common growth kinase-related oncogenes (K-ras, BRAF), tumour suppressor genes (p53, p16), gene methylation and cell adhesion-related genes related to the Wingless signalling pathway (E-cadherin and beta-catenin) from conventional colorectal adenocarcinoma. Colorectal SRCC also showed high expression of mucin-related genes and genes related to the gastrointestinal system. There was also a higher prevalence of microsatellite instability-high tumours and low Cox-2 expression in colorectal SRCC as opposed to conventional adenocarcinoma. CONCLUSIONS Colorectal SRCC has unique molecular pathological features. The unique molecular profiles in SRCC may provide molecular-based improvements to patient management in colorectal SRCC.

Multiple human single-stranded DNA binding proteins function in genome maintenance : structural, biochemical and functional analysis

DNA exists predominantly in a duplex form that is preserved via specific base pairing. This base pairing affords a considerable degree of protection against chemical or physical damage and preserves coding potential. However, there are many situations, e.g. during DNA damage and programmed cellular processes such as DNA replication and transcription, in which the DNA duplex is separated into two singlestranded DNA (ssDNA) strands. This ssDNA is vulnerable to attack by nucleases, binding by inappropriate proteins and chemical attack. It is very important to control the generation of ssDNA and protect it when it forms, and for this reason all cellular organisms and many viruses encode a ssDNA binding protein (SSB). All known SSBs use an oligosaccharide/oligonucleotide binding (OB)-fold domain for DNA binding. SSBs have multiple roles in binding and sequestering ssDNA, detecting DNA damage, stimulating strand-exchange proteins and helicases, and mediation of protein–protein interactions. Recently two additional human SSBs have been identified that are more closely related to bacterial and archaeal SSBs. Prior to this it was believed that replication protein A, RPA, was the only human equivalent of bacterial SSB. RPA is thought to be required for most aspects of DNA metabolism including DNA replication, recombination and repair. This review will discuss in further detail the biological pathways in which human SSBs function.

Use of reverse phase protein microarrays and reference standard development for molecular network analysis of metastatic ovarian carcinoma

Cancer can be defined as a deregulation or hyperactivity in the ongoing network of intracellular and extracellular signaling events. Reverse phase protein microarray technology may offer a new opportunity to measure and profile these signaling pathways, providing data on post-translational phosphorylation events not obtainable by gene microarray analysis. Treatment of ovarian epithelial carcinoma almost always takes place in a metastatic setting since unfortunately the disease is often not detected until later stages. Thus, in addition to elucidation of the molecular network within a tumor specimen, critical questions are to what extent do signaling changes occur upon metastasis and are there common pathway elements that arise in the metastatic microenvironment. For individualized combinatorial therapy, ideal therapeutic selection based on proteomic mapping of phosphorylation end points may require evaluation of the patient's metastatic tissue. Extending these findings to the bedside will require the development of optimized protocols and reference standards. We have developed a reference standard based on a mixture of phosphorylated peptides to begin to address this challenge.

B-Raf mutation : a key player in molecular biology of cancer

B-Raf is one of the more commonly mutated proto-oncogenes implicated in the development of cancers. In this review, we consider the mechanisms and clinical impacts of B-Raf mutations in cancer and discuss the implications for the patient in melanoma, thyroid cancer and colorectal cancer, where B-Raf mutations are particularly common.

Oestrogen and progestin responses in human endometrium

Our understanding of the mechanisms of the actions of oestrogens and progestins have evolved from the simple concept of nuclear receptor-mediated regulation of transcription to a highly sophisticated, finely tuned interplay between various coregulators, other signaling cascades and transcription factors. The net result of these complex regulatory mechanisms is a steroid-, cell-, or tissue-specific action of oestrogens and progestins. their antagonists or selective modulators of their receptors. In this review, we have attempted to shed some light on the regulation of the actions of oestrogens and progestins on the human endometrium. (C) 2003 Elsevier Science Ltd. All rights reserved.

Effects of selective oestrogen receptor modulators on proliferation in tissue cultures of pre- and postmenopausal human endometrium

We characterised the effects of selective oestrogen receptor modulators (SERM) in explant cultures of human endometrium tissue. Endometrium tissues were cultured for 24 h in Millicell-CM culture inserts in serum-free medium in the presence of vehicle,17 beta-estradiol (17 beta-E2,1 nM), oestrogen receptor (ER) antagonist ICI 164.384 (40 nM), and 4-OH-tamoxifen (40 nM), raloxifene (4 nM), lasofoxifene (4 nM)and acolbifene (4 nM). Protein expression of ER alpha, ER beta 1 and Ki-67 were evaluated by immunohistochemistry (IHC). The proliferative fraction was assessed by counting the number of Ki-67 positive cells. Nuclear staining of ER( and ER(1 was observed in the glandular epithelium and stroma of pre- and postmenopausal endometrium. ER(1 protein was also localized in the endothelial cells of blood vessels. Treating premenopausal endometrium tissue with 17 beta-E2 increased the fraction of Ki-67 positive cells (p < 0.001) by 55% in glands compared to the control. Raloxifene (4 nM) increased (p < 0.05) the Ki-67 positive fraction. All other SERMS did not affect proliferation in this model. Treating postmenopausal endometrium with 17(-E2 increased (p < 0.001) the fraction of Ki-67 positive cells by 250% in glands compared to the control. A similar effect was also seen for 4-OH-tamoxifen, whereas the rest of SERMs did not stimulate proliferation. We demonstrated that oestradiol increases the fraction of proliferating cells in short term explant cultures of postmenopausal endometrium. In addition, we were able to reveal the agonistic properties of 4-OH-tamoxifen and confirm that raloxifene and next-generation SERMs acolbifene and lasofoxifene were neutral on the human postmenopausal endometrium. (C) 2008 Elsevier Ltd. All rights reserved.

Inventing life: Patent law and synthetic biology

With promises of improved medical treatments, greener energy and even artificial life, the field of synthetic biology has captured the public imagination and attracted significant government and commercial investment. This excitement reached a crescendo on 21 May 2010, when scientists at the J Craig Venter Institute in the United States announced that they had made a “self-replicating synthetic bacterial cell”. This was the first living cell to have an entirely human-made genome, which means that all of the cell’s characteristics were controlled by a DNA sequence designed by scientists. This achievement in biological engineering was made possible by combining molecular biotechnology, gene synthesis technology and information technology.

Relaxin stimulates leukocyte adhesion and migration through a relaxin receptor LGR7-dependent mechanism

Leukocytes are critical effectors of inflammation and tumor biology. Chemokine-like factors produced by such inflammatory sites are key mediators of tumor growth that activate leukocytic recruitment and tumor infiltration and suppress immune surveillance. Here we report that the endocrine peptide hormone, relaxin, is a regulator of leukocyte biology with properties important in recruitment to sites of inflammation. This study uses the human monocytic cell line THP-1 and normal human peripheral blood mononuclear cells to define a novel role for relaxin in regulation of leukocyte adhesion and migration. Our studies indicate that relaxin promotes adenylate cyclase activation, substrate adhesion, and migratory capacity of mononuclear leukocytes through a relaxin receptor LGR7-dependent mechanism. Relaxin-stimulated cAMP accumulation was observed to occur primarily in non-adherent cells. Relaxin stimulation results in increased substrate adhesion and increased migratory activity of leukocytes. In addition, relaxin-stimulated substrate adhesion resulted in enhanced chemotaxis to monocyte chemoattractant protein-1. These responses in THP-1 and peripheral blood mononuclear cells are relaxin dose-dependent and proportional to cAMP accumulation. We further demonstrate that LGR7 is critical for mediating these biological responses by use of RNA interference lentiviral short hairpin constructs. In summary, we provide evidence that relaxin is a novel leukocyte stimulatory agent with properties affecting adhesion and chemomigration

Limitations and challenges in MSC delivery for bone regeneration

Objective: Regeneration of osseous defects by tissue-engineering or cell delivery approach provides a novel means of treatment utilizing cell biology, materials sciences, and molecular biology. The concept of in vitro explanted mesenchymal stem cells (MSCs) with an ability to induce new bone formation has been demonstrated in some small animal models. However, contradictory results have been reported regarding the regenerative capacity of MSCs after ex vivo expansion due to the lack of the understanding of microenvironment for MSC differentiation in vivo. ----- ----- Methods: In our laboratory tissue-derived and bone marrow-derived MSCs have been investigated in their osteogenesis. Cell morphology and proliferation were studied by microscopy, confocal microscopy, FACS and cell counting. Cell differentiation and matrix formation were analysed by matrix staining, quantitative PCR, and immunohistochemistry. A SCID skull defect model was used for cell transplantation studies.----- ----- Results: It was noted that tissue-derived and bone marrow-derived MSCs showed similar characteristics in cell surface marker expression, mesenchymal lineage differentiation potential, and cell population doubling. MSCs from both sources could initiate new bone formation in bone defects after delivery into a critical size defects. The bone forming cells were from both transplanted cells and endogenous cells from the host. Interestingly, the majority of in vitro osteogenic differentiated cells did not form new bone directly even though mineralized matrix was synthesized in vitro by MSCs. Furthermore, no new bone formation was detected when MSCs were transplanted subcutaneously.----- ----- Conclusion: This study unveiled the limitations of MSC delivery in bone regeneration and proposed that in vivo microenvironment needs to be optimized for MSC delivery in osteogenesis.

Periodontal regeneration and mesenchymal stem cells

The ultimate goal of periodontal therapy is to regenerate periodontal supporting tissues, but this is hard to achieve as the results of periodontal techniques for regeneration are clinically unpredictable. Stem cells owing to their plasticity and proliferation potential provides a new paradigm for periodontal regeneration. Stem cells from mesenchyme can self renew and generate new dental tissues (including dentin and cementum), alveolar bone and periodontal ligament, and thus they have great potential in periodontal regeneration. This chapter presents an insight into mesenchymal stem cells and their potential use in periodontal regeneration. In this chapter the cellular and molecular biology in periodontal regeneration will be introduced, followed by a range of conventional surgical procedures for periodontal regeneration will be discussed. Mesenchymal stem cells applied in regenerated periodontal tissue and their biological characterizations in vitro will be also introduced. Lastly, the use of mesenchymal stem cell to repair periodontal tissues in large animal models will be also reviewed.