No abstract

CSN6 is one subunit of the highly conserved constitutive photomorphogenesis 9 (COP9) signalosome (CSN), which is overexpressed in many types of cancers, and has received great attention as a regulator of the degradation of cancer-related proteins, suggesting its importance in oncogenic activity. CSN6 has been shown to be overexpressed in cervical cancer (CC) and associated with CC development. CC remains to be one of the most aggressive cancers affecting women. Cathepsin L (CTSL), significantly associated with the autophagy, plays a critical role in degradation of extracellular matrix for metastasis. However, the detailed biological functions of CSN6 on CTSL in CC metastasis have not been well clarified. Our data has shown that CSN6 and CTSL are positively correlated. The overexpression of CSN6 and CTSL might be a strong indicator for CC enhanced aggressiveness. CSN6 could suppress the degradation of CTSL, then facilitated the migration and invasion of CC cells. Interestingly, our results indicated that autophagy is essential for decreasing CTSL, while CSN6 could inhibit the autophagy ability of CC cells. In addition, blocking of the mammalian target of rapamycin (mTOR) pathway reversed CSN6-mediated autophagy inhibition. We further demonstrated that CSN6 positively regulated CTSL expression through an autophagy-lysosomal system. Taken together, we concluded that CSN6 might promote the migration and invasion of cervical cancer cells by inhibiting autophagic degradation of CTSL and serve as a potential gene therapy target for the treatment of CC metastasis.

Abstract. c-Jun activation domain-binding protein-1 (Jab1) is a multifunctional protein involved in cell proliferation and apoptosis, DNA damage and repair and genome stability. In a number of types of human carcinoma, the abnormal expression of Jab1 is associated with poor prognosis, suggesting that Jab1 serves a vital function in tumorigenesis. However, the functional effects and the underlying molecular mechanisms of Jab1 in laryngeal squamous cell carcinoma (LSCC) progression remain poorly understood. The results of the present study demonstrate that downregulating Jab1 expression promotes LSCC apoptosis while inhibiting the proliferation of LSCC cells. Furthermore, Jab1 inhibition results in decreased protein kinase B phosphorylation accompanied by increased caspase-3 cleavage and p53 expression. It has been identified that the increased expression of Jab1 is markedly associated with LSCC progression, therefore Jab1 may be used as a novel target for the treatment of laryngeal cancer.