Chromogenic in situ hybridization analysis of melastatin mRNA expression in melanomas from American Joint Committee on Cancer stage I and II patients with recurrent melanoma.
OBJECTIVE
To determine whether loss of melastatin (MLSN) is a universal phenomenon in American Joint Committee on Cancer (AJCC) stage I and II melanoma patients who experienced recurrence.


METHODS
Paraffin blocks of primary melanomas (PMs) were retrieved from 30 patients who had a negative sentinel lymph node biopsy and developed recurrent melanoma (AJCC stage I and II). Chromogenic in situ hybridization (CISH) methods were utilized to evaluate the expression of MLSN mRNA. These results were correlated with clinicopathologic data.


RESULTS
Variable, heterogeneous expression of MLSN mRNA was identified in normal, in situ and invasive melanocytes within and between cases. For the invasive PM component, 24 (80%) had focal, regional or complete loss of MLSN mRNA. The remaining 20% had either regional or total partial downregulation of MLSN mRNA. Intact MLSN mRNA expression was present regionally in 14/30 (47%), with mean relative tumor area of 38%, range 5-85%. Increasing loss of MLSN mRNA significantly correlated with increasing tumor depth and microsatellites (r = 0.1/0.4, p = 0.04). However, thin, AJCC T stage 1a PM had higher relative mean loss than intermediate AJCC T stage 2a/2b/3a thickness PM (65% vs. 34%/48%/25%). Increasing loss of MLSN mRNA significantly impacted on disease free survival (DFS) by multivariate analysis (58 vs. 0% 2 years DFS, < or = 75 vs. > 75% mRNA loss, p = 0.02). Decreased overall survival significantly correlated with increasing age and vascular invasion on multivariate analysis.


CONCLUSIONS
Extensive loss of MLSN in PM correlated with aggressive metastatic melanoma. Ancillary testing for MLSN mRNA expression by CISH could offer a means to more accurately identify AJCC stage I and II patients at risk for metastatic disease, who could benefit from adjuvant therapy.
Hammock
L
L
Johns Hopkins Hospital, Baltimore, MD, USA.
Cohen
C
C
Carlson
G
G
Murray
D
D
Ross
J S
JS
Sheehan
C
C
Nazir
T M
TM
Carlson
J A
JA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D002863:Chromogenic Compounds; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D017403:In Situ Hybridization / Q000379:methods*; D008297:Male; D008544:Melanocytes / Q000378:metabolism / Q000473:pathology; D008545:Melanoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000378:metabolism / Q000473:pathology; D009367:Neoplasm Staging; D011379:Prognosis; D012333:RNA, Messenger / Q000032:analysis; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016019:Survival Analysis; D015996:Survival Rate; D050053:TRPM Cation Channels / Q000096:biosynthesis* / Q000235:genetics
D014408:Biomarkers, Tumor; D002863:Chromogenic Compounds; D012333:RNA, Messenger; D050053:TRPM Cation Channels; C492059:TRPM1 protein, human