Loss of MDA-7 expression with progression of melanoma.
OBJECTIVE
Ectopic transfer of the melanoma differentiation-associated gene-7 (mda-7) has been shown in vitro to suppress growth and induce apoptosis in a variety of human tumor cell lines; similar effects are not elicited in normal cells. Thus, the mda-7 gene seems to function as a novel tumor suppressor, and there is interest in the potential of mda-7 gene transfer as cancer therapy. The objective of this study was to determine if MDA-7 protein is lost during primary melanoma progression from superficial to invasive stages and from localized to metastatic tumor. As a secondary objective, we analyzed MDA-7 protein expression in primary melanomas for correlation with predictors of outcome and with survival.


METHODS
MDA-7 protein expression was evaluated by immunohistochemistry in 41 primary melanomas and 41 metastases, including 24 paired samples. Each sample was scored for the percentage of positive cells and the overall intensity of immunolabeling.


RESULTS
Significant decreases in MDA-7 immunostaining, reflected in both number and intensity scores, were observed when comparing the intraepidermal and superficially invasive portions with the deeply invasive portions of primary tumors. Significant differences were also observed when comparing primary tumors to paired metastases.


CONCLUSIONS
Downregulation of MDA-7 expression in primary melanomas facilitates progression to invasive and metastatic stages. These data support the development of Ad-mda7 as gene therapy for advanced melanoma.
Ellerhorst
Julie A
JA
Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030-4095, USA. jaellerh@mail.mdanderson.org
Prieto
Victor G
VG
Ekmekcioglu
Suhendan
S
Broemeling
Lyle
L
Yekell
Sandra
S
Chada
Sunil
S
Grimm
Elizabeth A
EA
D004273:DNA, Neoplasm / Q000235:genetics*; D018450:Disease Progression; D015536:Down-Regulation; D016147:Genes, Tumor Suppressor; D006133:Growth Substances / Q000032:analysis / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D007378:Interleukins; D008545:Melanoma / Q000235:genetics* / Q000473:pathology*; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D011237:Predictive Value of Tests; D011379:Prognosis; D012878:Skin Neoplasms / Q000235:genetics* / Q000473:pathology*; D016019:Survival Analysis; D000099180:Interleukin-24
D004273:DNA, Neoplasm; D006133:Growth Substances; D007378:Interleukins; D000099180:Interleukin-24