Mouse anti-Human Metablastin monoclonal antibody, clone 64

Pheochromocytomas of the adrenal medulla may be life-threatening catecholamine-producing tumors which are malignant in about 10% of cases. Differential diagnosis between malignant and benign tumors is dependent on the development of metastasis or extensive local invasion. A number of genetic aberrations have been described in pheochromocytomas, but no marker associated to malignancy has been reported. We applied an expression microarray containing 7770 cDNA clones and analysed the expression profiles in eleven tumors compared to normal adrenal medulla. Stathmin (STMN1, Op18) was most conspiciously overexpressed among the differentially expressed genes. RT-PCR analysis further confirmed mRNA overexpression, 6 to 8-fold for benign and malignant tumors, and 16-fold for metastases. Stathmin protein overexpression was observed by immunohistochemistry, and distinct differential protein expression between benign and malignant/metastasis specimens was confirmed by Western blot analysis. The results introduce stathmin as a possible diagnostic marker for malignant pheochromocytomas, and further evaluations are warranted.

STMN1 has been regarded as an oncogene and its upregulation is closely associated with malignant behavior and poor prognosis in multiple cancers. However, the detailed functions and underlying mechanisms of STMN1 are still largely unknown in hepatocellular carcinoma (HCC) development. Herein, we analyzed STMN1 expression and the related clinical significance in HCC by using well-established Protein Atlas, The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) cancer databases. Analysis indicated that STMN1 was highly expressed in HCC and closely associated with vascular invasion, higher histological grade, advanced clinical grade and shorter survival time in HCC patients. Overexpressing and silencing STMN1 in HCC cell lines showed that STMN1 could regulate cell proliferation, migration, drug resistance, cancer stem cell properties in vitro as well as tumor growth in vivo. Further experiments showed that STMN1 mediated intricate crosstalk between HCC and hepatic stellate cells (HSC) by triggering the hepatocyte growth factor (HGF)/ MET signal pathway. When HSC were cocultured with HCC cells, HSC secreted more HGF to stimulate the expression of STMN1 in HCC cells. Mutually, STMN1 upregulation in HCC cells facilitated HSC activation to acquire cancer-associated fibroblast (CAF) features. The MET inhibitor crizotinib significantly blocked this crosstalk and slowed tumor growth in vivo. In conclusion, our findings shed new insight on STMN1 function, and suggest that STMN1 may be used as a potential marker to identify patients who may benefit from MET inhibitor treatment.