gastrin-releasing-peptide and Skin-Neoplasms

The elevated expression and receptor binding of gastrin-releasing peptide (GRP) in various types of cancer, especially in malignant melanoma of the skin, suggest that GRP might be a putative target for immunotherapy in neoplastic diseases. We have therefore constructed a novel DNA vaccine coding for six tandem repeats of a fragment of GRP from amino acids 18 to 27 (GRP6) flanked by helper T-cell epitopes for increased immunogenicity, including HSP65, a tetanus toxoid fragment from amino acids 830 to 844 (T), pan-HLA-DR-binding epitope (PADRE) (P), and two repeats of a mycobacterial HSP70 fragment from amino acids 407 to 426 (M). The anti-GRP DNA vaccine (pCR3.1-VS-HSP65-TP-GRP6-M2) was constructed on a backbone of a pCR3.1 plasmid vector with eight 5'-GACGTT-3' CpG motifs and the VEGF183 signal peptide (VS). Intramuscular (IM) injections of anti-GRP vaccine in mice stimulated the production of high titers of specific antibodies against GRP and suppressed the growth of subcutaneous tumors of B16-F10 melanoma cells. Parallel results were obtained in vitro, showing inhibition of B16-F10 cell proliferation by GRP antisera. IM injections of the DNA vaccine also significantly attenuated tumor-induced angiogenesis associated with intradermal tumors of B16-F10 cells. In addition, lung invasion of intravenously injected cells was highly diminished, suggesting potent antimetastatic activity of the DNA vaccine. These findings support the highly immunogenic and potent antitumorigenic activity of specific anti-GRP antibodies elicited by the anti-GRP DNA vaccine.

Topics: Animals; Antibodies; Cancer Vaccines; Cell Line; CpG Islands; Epitopes, T-Lymphocyte; Gastrin-Releasing Peptide; Injections, Intramuscular; Lung Neoplasms; Male; Melanoma; Mice; Mice, Inbred C57BL; Plasmids; Skin Neoplasms; Vaccines, DNA

Gastrin-releasing peptide (GRP), the mammalian counterpart of bombesin, was first identified in the nervous system of the gastrointestinal tract. Little is known about its distribution in the human skin or about its function in certain diseases such as malignant melanoma. Recently functional GRP receptors have been found on human melanoma cell lines. We therefore investigated, using immunohistochemistry, whether human melanoma cells express GRP and whether there is a significant change in its distribution among the different clinical types of melanoma and a connection to histopathological features such as growth phase, type of malignant cells, Breslow thickness and Clark level of invasion. We demonstrated the existence of GRP in all clinicopathological types of melanoma; a predilection for quantitatively increased GRP immunostaining was noticed in nodular melanomas (P = 0.007). As well as this, we observed a restriction of GRP expression at a specific level of invasion, i.e. within the reticular dermis (Clark IV) (P = 0.032). GRP immunoreactivity was found to be associated with an increased amount of melanin pigment in malignant cells (P = 0.054). The presence of GRP in malignant melanocytes, along with its association with the various histopathological features, suggests that GRP may play a role in the pathophysiology of this type of cutaneous tumour.

Topics: Gastrin-Releasing Peptide; Humans; Immunoenzyme Techniques; Melanocytes; Melanoma; Neoplasm Invasiveness; Skin; Skin Neoplasms

Topics: 3T3 Cells; Animals; Bombesin; Cell Adhesion; Cytoskeleton; Gastrin-Releasing Peptide; Humans; Immunohistochemistry; Melanocytes; Melanoma; Mice; Phosphorylation; Skin; Skin Neoplasms; Vasoconstrictor Agents; Vasopressins