Mechanisms by which genes encoding growth factors and growth factor receptors contribute to malignant transformation

Injectable platelet-rich fibrin influences the behavior of gingival mesenchymal stem cells

In this study, we examined the effects of injectable platelet-rich fibrin (iPRF) on proliferation and osteodifferentiation in mesenchymal stem cells (MSCs) isolated from human gingiva. Gingival MSCs (gMSCs) were grown in experimental culture media with different concentrations of iPRF [5%, 10%, and replacement of fetal calf serum (FCS) in the standard media with 10% iPRF–10% iPRF-FCS]. Immunophenotyping of gMSCs was performed after seven days by flow cytometry, and their proliferation was examined after three and seven days using the Cell Counting Kit-8 method. After 14 days in culture, spontaneous osteogenic differentiation of gMSCs was evaluated via real-time polymerase chain reaction. All gMSCs were positive for cluster of differentiation (CD) 105, CD73, CD90, and CD44, and negative for CD34/45, CD14, CD79a, and human leukocyte antigen, DR isotype (HLA-DR). Reduced expression of some surface antigens was observed in the gMSCs grown in 10% iPRF-FCS medium compared to the other groups. After three days, gMSCs grown in 10% iPRF had proliferated significantly less than the other groups. After seven days, proliferation was significantly higher in the 5% iPRF cells compared to the control, while proliferation in the 10% iPRF and 10% iPRF-FCS groups was significantly lower. No spontaneous osteogenic differentiation was observed in the presence of iPRF, as observed by low runt-related transcription factor 2 (RUNX2) expression. Some expression of secreted protein acidic and cysteine rich (SPARC) and collagen 1 alpha (COL1A) was observed for all the gMSCs regardless of the culture medium composition. gMSCs grown in 10% iPRF had significantly lower SPARC expression. In conclusion, 5% iPRF stimulated gMSC proliferation, and an excessively high concentration of iPRF can impair osteogenic induction.

Investigation of modified platelet-rich plasma (mPRP) in promoting the proliferation and differentiation of dental pulp stem cells from deciduous teeth

Stem cells from human exfoliated deciduous teeth (SHEDs) have great potential to treat various dental-related diseases in regenerative medicine. They are usually maintained with 10% fetal bovine serum (FBS) in vitro. Modified platelet-rich plasma (mPRP) would be a safe alternative to 10% FBS during SHEDs culture. Therefore, our study aimed to compare the proliferation and differentiation of SHEDs cultured in mPRP and FBS medium to explore an optimal concentration of mPRP for SHEDs maintenance. Platelets were harvested by automatic blood cell analyzer and activated by repeated liquid nitrogen freezing and thawing. The platelet-related cytokines were examined and analyzed by ELISA. SHEDs were extracted and cultured with different concentrations of mPRP or 10% FBS medium. Alkaline phosphatase (ALP) activity was measured. Mineralization factors, RUNX2 and OCN, were measured by real-time PCR. SHEDs were characterized with mesenchymal stem cells (MSCs) markers including vimentin, CD44, and CD105. mPRP at different concentrations (2, 5, 10, and 20%) enhanced the growth of SHEDs. Moreover, mPRP significantly stimulated ALP activity and promoted expression of RUNX2 and OCN compared with 10% FBS. mPRP could efficiently facilitate proliferation and differentiation of SHEDs, and 2% mPRP would be an optimal substitute for 10% FBS during SHEDs expansion and differentiation in clinical scale manufacturing.

Therapeutic potential of siRNA and DNAzymes in cancer

Cancer is characterized by uncontrolled cell growth, invasion, and metastasis and possess threat to humans worldwide. The scientific community is facing numerous challenges despite several efforts to cure cancer. Though a number of studies were done earlier, the molecular mechanism of cancer progression is not completely understood. Currently available treatments like surgery resection, adjuvant chemotherapy, and radiotherapy are not completely effective in curing all the cancers. Recent advances in the antisense technology provide a powerful tool to investigate various cancer pathways and target them. Small interfering RNAs (siRNAs) could be effective in downregulating the cancer-associated genes, but their in vivo delivery is the main obstacle. DNA enzymes (DNAzymes) have great potential in the treatment of cancer due to high selectivity and significant catalytic efficiency. In this review, we are focusing on antisense molecules such as siRNA and DNAzymes in cancer therapeutics development. This review also describes the challenges and approaches to overcome obstacles involved in using siRNA and DNAzymes in the treatment of cancers.

Mechanisms of cell-cycle checkpoints: at the crossroads of carcinogenesis and drug discovery

Human tumors arise from multiple genetic changes that gradually transform growth-limited cells into highly invasive cells that are unresponsive to growth controls. The genetic evolution of normal cells into cancer cells is largely determined by the fidelity of DNA replication, repair, and division. Cell-cycle arrest in response to stress is integral to the maintenance of genomic integrity. The control mechanisms that restrain cell-cycle transition or induce apoptotic signaling pathways after cell stress are known as cell-cycle checkpoints. This review will focus on the mechanisms of cell-cycle checkpoint pathways and how different components of these pathways are frequently altered in the genesis of human tumors. As our knowledge of cell-cycle regulation and checkpoints increases, so will our understanding of how xenobiotic agents can affect these processes to either initiate or inhibit tumorigenesis.

DNA sequence and functional characterization of the human and rat epidermal growth factor promoter: regulation by cell growth

Epidermal growth factor (EGF) regulates cell growth and differentiation through intracellular transduction networks activated by its tyrosine kinase receptor, EGFR. In this report we describe the structure and DNA sequence of transcriptional control regions from both human and Wistar-rat single copy EGF genes and their functional analysis in epithelial cell cultures. By sequence comparison we show these proximal gene regions have remained conserved in evolution to -640 (relative to the rodent mRNA initiation site), where similarity is interrupted by a rodent interspersed-repeat element (SINE). Transcript mapping reveals complexity in EGF initiation site selection: whereas a single rat liver initiation site (+1) appears 30bp 3' to the TTTAA element, an additional upstream site is detected in kidney RNA at -14. In contrast, in human RNA a single initiation is observed, which is displaced 12bp 3' to the rodent RNA terminus. Both promoters were defined in transient expression assays. Our results show the human promoter to be at least 20-fold more active than the equivalent rodent sequence, although both are activated during cell proliferation and negatively regulated in contact inhibited and quiescent cultures. The results indicate EGF gene expression and cell division are temporally linked, suggesting its promoter comprises a growth responsive regulatory domain.

Distinct patterns of expression of keratinocyte growth factor and its receptor in endometrial carcinoma

BACKGROUND

Keratinocyte growth factor (KGF) is a member of the fibroblast growth factor (FGF) family. KGF is a stromally derived, paracrine growth factor specifically mitogenic for a variety of epithelial cells. The KGF receptor (KGFR), which is a splice variant of the FGF receptor-2 (FGFR-2)/bek gene, is expressed only in epithelial cells. In this study, the expression of mRNAs encoding KGF, KGFR, and FGFR-2 in endometrial adenocarcinoma and in carcinosarcoma tissues was examined and the expression of the same mRNAs was compared with cycling endometrium.

METHODS

Specimens of tumor tissue were collected from 14 women with well differentiated endometrial adenocarcinoma and from 4 women with carcinosarcoma. All samples were obtained at the primary surgery before any treatment was initiated. In addition, endometrial tissues from 19 premenopausal women with normal menstrual cycles were examined. The expression of specific mRNAs in the endometrial samples was assessed using quantitative reverse transcriptase polymerase chain reaction. The results were analyzed by the nonparametric Kruskal-Wallis statistic.

RESULTS

The KGF mRNA expression was significantly lower in endometrial adenocarcinoma tissue compared with cycling endometrial tissues, whereas no difference was found between carcinosarcoma tissue and cycling endometrium. The relative level of KGFR mRNA in endometrial adenocarcinoma did not differ from that in cycling endometrium, but was significantly higher compared with carcinosarcomas. No differences were observed in FGFR-2 mRNA expression between cycling endometrium and tumor tissues.

CONCLUSIONS

To the authors' knowledge, this study demonstrates for the first time the expression of KGF, KGFR, and FGFR-2 mRNAs in endometrial adenocarcinoma and in carcinosarcoma tissues. The relative level of KGF mRNA expression in adenocarcinoma tissue is decreased compared with that in cycling endometrium. The change in epithelial/stromal cell prominence between cycling endometrium and adenocarcinoma tissue may account for the difference in KGF expression but does not explain why KGF receptor expression in same tissues remains unchanged. The impact of altered KGF expression for endometrial tumorigenesis is still unknown.

Human breast cancer cell lines as models of growth regulation and disease progression

The routine isolation and culture of human breast cancer cells from patient samples has been a goal of breast cancer cell biologists for over 30 years. Despite extensive work in this area and the development of many human breast cancer cell lines, the proportion of patient samples that give rise to immortalized breast cancer cell lines is still disappointingly low. The majority of human breast cancer cell lines that have been established were isolated many years ago and have been grown continuously under poorly defined culture conditions. These cell lines have been useful for studies of the estrogen receptor biology in human breast cancer cells, in identifying growth factors synthesized by breast cancer cells, and for the characterization of genetic alterations in oncogenes and tumor suppressor genes present in these cells. More recently, tissue culture methods have improved, resulting in the ability to culture routinely normal human mammary epithelial cells of specific lineages and this has resulted in the development of new human breast cancer cell lines. The ability to isolate and culture normal and neoplastic human mammary epithelial cells under similar culture conditions has improved these models dramatically and has resulted in the identification of altered cellular phenotypes of human breast cancer cells.

Different proteins in the hemolymph sera from sarcomatous and healthy soft shell clams, Mya arenaria L

1. Serum proteins showed quantitative and qualitative differences between sarcomatous and healthy soft shell clams, Mya arenaria L. 2. Total protein concentration was significantly higher in the serum of sarcomatous clams than of healthy clams. 3. According to SDS-PAGE, more serum proteins with more variability distinguished sarcomatous clams from healthy ones. 4. Sarcomatous clams had unique serum proteins of M(r)23,000, 45,000 and 54,000. Healthy clams had unique serum proteins of M(r) 24,000, 103,000 and 105,000. 5. During disease progression, sarcoma-specific proteins appeared while normal proteins disappeared. 6. We propose that some sarcoma-associated proteins may have tumor promoting and/or cytotoxic functions and that some normal proteins which disappear during disease progression may be involved in the humoral defense system.

Activation of muscarinic acetylcholine receptors inhibits cell cycle progression of small cell lung carcinoma

We previously reported that activation of muscarinic acetylcholine receptors (mAChR) of M3 subtype causes hydrolysis of phosphoinositides and inhibits voltage-gated Ca2+ channel activity in small cell lung carcinoma (SCLC) cells. We now report that mAChR activation causes exponentially growing SCLC cells to arrest in S and G2/M phases of the cell cycle, concomitant with a decrease in DNA synthesis. Cell cycle progression and DNA synthesis resume when mAChR are down-regulated. In serum-starved SCLC cells, mAChR activation inhibits DNA synthesis induced by serum, bombesin, insulin, or insulin-like growth factor-I. The finding that DNA synthesis is inhibited even when mAChR are activated after exposure of cells to growth factors indicates that decreased signal transduction by growth factor receptors is not the mechanism of mAChR-mediated growth inhibition. Our data suggest that mAChR activation disrupts a common event that is induced by different growth factors and is fundamental for cell cycle progression.