3918

LAMC2

laminin, gamma 2;LAMC2;laminin, gamma 2

BM600-100kDa|CSF 140 kDa subunit|cell-scattering factor 140 kDa subunit|epiligrin subunit gamma|kalinin subunit gamma|ladsin 140 kDa subunit|laminin B2t chain|laminin subunit gamma-2|large adhesive scatter factor 140 kDa subunit|nicein subunit gamma

1q25-q31

protein-coding

Little is known about which genes mediate metastasis in bladder cancer, which accounts for much of the mortality of this disease. We used human bladder cancer cell lines to develop models of two clinically common metastatic sites, lung and liver, and evaluated their gene expression with respect to human tumor tissues. Parental cells were injected into either the murine spleen to generate liver metastases or tail vein to generate lung metastases with sequential progeny derived by re-injection and comparisons made of their organ-specific nature by crossed-site injections. Both genomic and transcriptomic analyses of organ-selected cell lines found salient differences and shared core metastatic profiles, which were then screened against gene expression data from human tumors. The expression levels of laminin V gamma 2 (LAMC2) contained in the core metastatic signature were increased as a function of human tumor stage, and its genomic location was in an area of gain as measured by comparative genomic hybridization. Using immunohistochemistry in a human bladder cancer tissue microarray, LAMC2 expression levels were associated with tumor grade, but inversely with nodal status. In contrast, in node-negative patients, LAMC2 expression was associated with visceral metastatic recurrence. In summary, LAMC2 is a novel biomarker of bladder cancer metastasis that reflects the propensity of cells to metastasize via either lymphatic or hematogenous routes.

Laminin-332 (Ln-332) is a heterotrimeric glycoprotein (alpha3beta3gamma2) unique to epithelial cells with crucial roles in signaling, adhesion, and migration. Altered localization or expression levels of Ln-332, particularly its gamma2 subunit, are of prognostic value in a variety of cancers. However, the lack of standardized methodology and the limited quantification of previous study results have left unanswered questions, including the role of gamma2 transcript variants and whether differential expression of this chain represents dysregulation of the whole heterotrimer. Herein, we test the hypothesis that mRNA changes in one or more Ln-332 encoding genes can be used to distinguish between early- and advanced-stage cancer specimens and shed light on mechanistic questions raised by previous studies. Statistical analyses of human microarray data from the publicly available expression project in Oncology (expO) dataset, including examination of the distributions of Ln-332 subunit mRNA levels, identified a significant decrease in the Ln-332 beta3:gamma2 mRNA ratio between normal (n = 10) and early-stage colon cancer (n = 29) specimens. The beta3:gamma2 ratio was further decreased in metastatic colon cancer (n = 41) compared with early-stage samples. Our findings raise the possibility that Ln-332 gamma2 may be a therapeutic target against metastatic colon cancer because a lowered beta3:gamma2 ratio would reduce expression of heterotrimeric Ln-332 and increase monomeric gamma2 secretion. Further, standardized, quantitative methods for patient prognosis and therapeutic choice could be developed based upon the Ln-332 mRNA changes we uncovered.

BACKGROUND: To investigate the potential role of laminin gamma2 and its correlation with prognosis in patients with extrahepatic cholangiocarcinoma (CCA). MATERIALS AND METHODS: Laminin gamma2 expression was evaluated by immunohistochemistry in 72 extrahepatic CCA patients after surgical resection. Knockdown of laminin gamma2 was achieved via small interfering RNA transfection in the extrahepatic CCA cell line QBC939. RESULTS: Thirty-six of 72 extrahepatic CCAs (50%) stained positive for laminin gamma2 in two types of patterns: stromal staining (28/72, 39%) and cytoplasmic staining (24/72, 33%). All 16 paracancerous tissue samples showed negative staining. Both stromal and cytoplasmic laminin gamma2 expressions correlated with lymph node metastasis. Kaplan-Meier analysis showed that aberrant expression of laminin gamma2 correlated with poor overall survival and early recurrence. Cox regression analysis further demonstrated that laminin gamma2 expression was a significant independent predictor of poor overall survival and early recurrence. Immunofluorescence staining revealed cytoplasmic expression of laminin gamma2 in QBC939 cells. Knockdown of laminin gamma2 significantly reduced QBC939 cell invasion and migration. CONCLUSIONS: Aberrant expression of laminin gamma2 correlates with poor prognosis and promotes invasion in extrahepatic CCA.

BACKGROUND: The laminin gamma2 chain is involved in tumor invasion and metastasis, but the significance of laminin gamma2 chain expression remains unclear in patients with pancreatic carcinoma. METHODS: Laminin gamma2 chain expression was examined immunohistochemically in 48 patients with pancreatic ductal adenocarcinoma who were followed closely to elucidate the correlations between clinicopathologic factors, postoperative recurrence, and overall survival. Prognostic factors for postoperative survival were examined comparing clinicopathologic factors and laminin gamma2 chain expression. RESULTS: Two different staining patterns of laminin gamma2 chain expression, cytoplasmic expression and basement membrane expression, were detected in tumors from all 48 patients. tumors were then classified into two types according to the dominant pattern of laminin gamma2 chain expression: the cytoplasmic expression dominant type (CYT; n = 26 patients) and the basement membrane expression dominant type (BM; n = 22 patients). tumor differentiation was associated statistically with the BM type of laminin gamma2 chain expression (P = 0.0002). The CYT type of laminin gamma2 chain expression was associated significantly with the occurrence of postoperative hepatic metastasis (P = 0.0011) and also was the strongest predictive factor for poorer overall survival in patients with pancreatic ductal adenocarcinomas (P = 0.0161). CONCLUSIONS: The cytoplasmic expression of the laminin gamma2 chain represents the high invasive potential of the tumor and is correlated with distant metastasis, especially hepatic metastasis, and with a poorer prognosis in patients with pancreatic ductal adenocarcinoma.