ABSTRACT
To examine the localization pattern of phospholipase D2 (PLD2) in the pancreatic islet (the islet of Langerhans) depending on species, we conducted a morphological experiment in the rat and guinea pig. Since individual islets display a typical topography with a central core of B cell mass and a peripheral boundary of A, D, and PP cells, double immunofluorescent staining with a panel of antibodies was performed to identify PLD2-immunoreactive cells in the islets PLD2 immunoreactivity was mainly present in A and PP cells of the rat pancreatic islets. And yet, in the guinea pig, PLD2 immunoreactivity was exclusively localized in A cells, and not in PP cells. These findings suggest a possibility that PLD2 is mainly located in A cells of rodent pancreatic islets, and that the existence of PLD2 in PP cells is not universal in all species. Based on these results, it is suggested that PLD2 may play a significant role in the function of A and/or PP cells via a PLD-mediated signaling pathway.
Subject(s)
Animals , Rats , Antibodies , Guinea Pigs , Guinea , Islets of Langerhans , Phospholipases , RodentiaABSTRACT
Phospholipase D (PLD) catalyzes the hydrolysis of phosphatidylcholine to phosphatidic acid and choline. A variety of signal molecules such as hormones, neurotransmitters, extracellular matrix molecules, and growth factors are known to induce the activation of PLD in a wide range of cell types. Hence PLD is implicated in a broad spectrum of physio-logical processes and diseases, including mitogenesis, cell differentiation, metabolic regulation, secretion, neural and cardiac stimulation, inflammation, oncogenesis, and diabetes. The signal-dependent activation of PLD has been observed in a variety of brain and neural-derived cells. In this paper, human chromosomal locations and developmental neural expression patterns in rat of PLD1 and PLD2 were investigated with fluorescent in situ hybridization (FISH) and in situ hybridization histochemistry, respectively. The PLD1 was assigned to human chromosome 3q26 and expressed most strikingly in selected ventricular neural cells lining spinal cord and brain during neuronal differentiation and migration period. The PLD2 was assigned to human chromosome 17p13.1 and expressed in differentiating ventricular neural cells and multiple regions of the postnatal rat brain.
Subject(s)
Animals , Humans , Humans , Rats , Brain , Carcinogenesis , Cell Differentiation , Choline , Chromosomes, Human , Extracellular Matrix , Hydrolysis , In Situ Hybridization , In Situ Hybridization, Fluorescence , Inflammation , Intercellular Signaling Peptides and Proteins , Neurons , Neurotransmitter Agents , Phosphatidic Acids , Phosphatidylcholines , Phospholipase D , Phospholipases , Spinal CordABSTRACT
BACKGROUND: Tumor invason and metastasis are the major causes of morbidity and death for cancer patients. Metastatic spread depends critically upon the invasiveness of the tumor cells, i.e., their ability to breach basement membrane by profusely secreting specific proteolytic enzymes such as MMP-2. TIMP-2 has a high affinity for progelatinase A and will form a 1:1 complex with either the latent or activated forms of the enzyme and has inhibitory activity against MMP-2. Laminin induced activation of Phospholipase D (PLD) and consequent generation of phosphatidic acid are involved in a signal propagation pathway leading to induction of MMP-2 in metastatic HT 1080 fibrosarcoma cells. We also studied a expression of PLD, MMP-2 and TIMP-2 in colorectal adenocarcinoma. METHODS: Colorectal adenocarcinomas from 13 patients in our hospital were studied for immunohistochemical expression of PLD, MMP-2, and TIMP-2 to assess their diagnostic and prognostic importance as well as relation between PLD and MMP-2. RESULTS: 1) Expression of PLD-2 was detected in 77% of the cases in colorectal adenocarcinomas. 2) MMP-2 expression was significantly associated with the presence of lymph-node metastasis, with moderated to strong expression present in 100% of the cases compared with 28.6% of the non-metastatic cases (P-value=0.017). 3) For colorectal adenocarcinomas, a strong correlation between PLD and MMP-2 expression was detected (P-value=0.008). CONCLUSION: PLD-2 can be used as a potential marker for malignant disease in colorectal adenocarcinomas. MMP-2 expression was significantly associated with the presence of lymph-nodemetastasis. A strong correlation between PLD and MMP-2 expression was also detected in colorectal carcinoma.