Cellular transformation is accomplished in vitro through the concerted action of growth factors and oncogenes. This association has demonstrated that malignant growth results from aberrations in pathways that normally operate to control proliferation. Activation of genes that code for growth factors, their receptors, and/or molecules essential in the transduction of signals from the cell surface to the nucleus are all potential mechanisms by which tumor cells could establish a selective growth advantage over normal cells. This dissertation addresses the question of what oncogenic mechanisms are important in the development and progression of human melanoma. These studies show that melanoma growth is regulated by endogenous substances produced by the melanoma cells themselves (autocrine stimulation), as well as by exogenous substances supplied by neighboring cells and platelets (paracrine stimulation). These factors work to drive the expression of the transformed phenotype for melanoma as evidenced by induction of serum-free soft agar growth. Human platelets were found to the the richest source of paracrine growth promoters. The factor from human platelets was characterized and partially purified. Melanoma cells respond to this 60,000 molecular weight, disulfide-bond-containing protein in colony formation assays. In addition, the protein has endothelial cell growth factor activity. Purified fractions which promoted optimal colony formation for human melanoma cells also maximally stimulated monolayer growth of bovine aortic endothelial cells, while melanocytes were nonresponsive. This implies that melanoma cells are expressing receptors for a protein which plays no known or apparent role in the normal growth of melanocytes. Melanoma cells are sensitive to growth regulatory molecules of autocrine and paracrine nature. This dissertation provides clues to the genetic lesions which have occurred in these melanoma cells to influence their proliferation. The aberrations appear to reside in those genes important in growth factor pathways at the level of endogenous production and misguided response to exogenous factors through receptor expression. We can not hope to fully inhibit the proliferation of tumor cells until we identify and understand those forces which drive their growth. These studies have increased our knowledge of those signals which stimulate melanoma cellular proliferation, and thus provide insight into important therapeutic targets.

No description available.

published_or_final_version / abstract / Anatomy / Master / Master of Philosophy

published_or_final_version / abstract / Clinical Oncology / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Paediatrics and Adolescent Medicine / Master / Master of Philosophy

published_or_final_version / abstract / Physiology / Master / Master of Philosophy

published_or_final_version / Chinese Medicine / Master / Master of Philosophy

published_or_final_version / Obstetrics and Gynaecology / Doctoral / Doctor of Philosophy

Twenty five surgical specimens of malignant human prostate, 3 lymph nodes with metastatic prostate carcinoma, 5 benign prostate hyperplasia (BPH), 11 normal human prostates, as well as 3 human prostate cell lines (DU-145, PC3 and LNCaP) were examined for the expression of human matrix metalloproteinase-7 gene (MMP-7) from the human collagenase family (originally called PUMP-1 for putative metalloproteinase-1) (Majid Siadat-Pajouh et al. 1991). Northern blots were prepared using total RNA extracted from 18 prostate adenocarcinomas, 4 BPH, 2 lymph nodes with metastatic prostate carcinoma and 11 normal human prostates. When the northern blots were hybridized with ³²P labeled MMP-7 cDNA probes, a 1.2 Kb mRNA was detected in 14 out 18 prostate adenocarcinomas, 1 out of 4 BPH, 1 out of 2 metastatic lymph nodes, and 3 out of 11 normal prostates. The 3 human prostate cell lines did not show any evidence of MMP-7 transcript. In situ hybridization was conducted using a ³⁵S labeled MMP-7 cRNA. In situ hybridization was carried out on seven prostate adenocarcinomas, 2 BPH, and 3 metastatic lymph nodes. In situ hybridization revealed that the MMP-7 gene was expressed in the epithelial cells of primary prostate adenocarcinoma as well as invasive and metastatic cells. MMP-7 expression was also seen focally in some benign epithelial cells but not in inflammatory cells or stroma. The combined results of northern analysis and in situ hybridization indicated that 72% of prostate adenocarcinomas, 66% of metastatic prostatic lymph nodes, 40% of BPH and 27% of normal prostate tissues express MMP-7 transcripts. Additional northern blot analysis was performed using probes to human type IV collagenase, type I collagenase and Stromelysin I in human prostate adenocarcinoma as well as normal prostate tissues. The results indicated that 6 out of 10 adenocarcinoma samples and none of the 4 normal samples were positive for type IV collagenase transcripts. None of the tissues examined for the expression of type I collagenase and stromelysin I were found to express the transcripts of interest at detectable levels. A monclonal antibody was generated against a 10 mer synthetic peptide unique to MMP-7. This antibody was reactive with the native protein in frozen prostate tissues. These data suggest that certain metalloproteinases are differentially expressed in prostatic adenocarcinoma and may play a role in invasion and metastasis.

No description available.