Oncology. and produces large amounts of lactate rather than synthesizing ATP (Li et al., 2016). Due to the increasing need for glycolysis, cancer cells are proficient in transporting extracellular glucose across the cell membrane into the cytoplasm by upregulating the expression of glucose transporter (GLUT) (Carvalho et al., 2011; Medina and Owen, 2002; Yu et al., 2017). To date, 14 GLUT proteins have been shown to be expressed in humans, and they are categorized into 3 classes based on sequence similarity (Mueckler and Thorens, 2013). GLUT1 is likely one of the most extensively studied proteins of all membrane transport systems. GLUT1 is generally undetectable in normal epithelial tissues, but the overexpression of GLUT1 has been reported in various cancers and VU661013 was shown to lead to increased glucose uptake into the cytoplasm of tumor cells (Yu et al., 2017). Tazarotene-induced gene VU661013 1 (TIG1) was identified in skin graft cultures treated with the synthetic retinoid tazarotene (Nagpal et al., 1996) and has also been identified as retinoic acid receptor responder 1 (RARRES1). TIG1 is expressed at high levels in benign or well-differentiated prostate and colon tissues (Jing et al., 2002; Wu et al., 2006), but CpG hypermethylation of the TIG1 promoter leads to the downregulation of TIG1 expression in cancer tissues derived from the liver (Chen et al., 2014), prostate (Jing et al., 2002; Zhang et al., 2004), head and neck (Kwok et al., 2009; Yanatatsaneejit et al., 2008), esophagus (Mizuiri et al., 2005), breast (Peng et al., 2012), stomach (Shutoh et al., 2005), and colon (Wu et al., 2006). Ectopic TIG1 expression leads to cellular autophagy and suppression of growth (Shyu et al., 2016; Tsai et al., 2011). TIG1 contains an N-terminal transmembrane domain that is structurally similar to the protein latexin. Although latexin possesses a carboxypeptidase inhibitor property, the exact role of the latexin-like domain in TIG1 remains unclear. The TIG1 gene is expressed in two isoforms, TIG1A and TIG1B, which are encoded by a 1.55-kb mRNA [GenBank: “type”:”entrez-nucleotide”,”attrs”:”text”:”NM_206963″,”term_id”:”1519243841″,”term_text”:”NM_206963″NM_206963] and an 883-bp mRNA [GenBank: “type”:”entrez-nucleotide”,”attrs”:”text”:”NM_002888″,”term_id”:”747165369″,”term_text”:”NM_002888″NM_002888], respectively. TIG1A is predicted to encode a33.3 kDa protein with 294 amino acids and TIG1B encodes a 228-amino acid protein with a molecular weight of 25.8 kDa (Wu et al., 2011). The TIG1A isoform (“type”:”entrez-protein”,”attrs”:”text”:”NP_996846.1″,”term_id”:”46255043″,”term_text”:”NP_996846.1″NP_996846.1) shares the N-terminal 224 amino acids with TIG1B (“type”:”entrez-protein”,”attrs”:”text”:”NP_002879.2″,”term_id”:”46255041″,”term_text”:”NP_002879.2″NP_002879.2). Although TIG1A has been detected, it does not have an obviously distinct cellular function in the Wnt signaling pathway (Tsai et al., 2011) or on regulating autophagic activity (Shyu et al., 2016). In addition, VU661013 previous studies examining the suppression of cell growth and invasion by TIG1 have focused on the TIG1B isoform (Jing et al., 2002; Kwok et al., 2009; Takai et al., 2005). DnaJ heat shock protein family member C8 (DNAJC8) belongs to the heat shock protein 40 (HSP40) family, which possesses a highly conserved J-domain of approximately 70 amino acids that regulates the activity of Hsp70 proteins (Demand et al., 1998). In addition, HSP40 proteins have been shown to inhibit protein aggregation in a J-domain independent manner (Bao et al., 2002; Ito et al., 2016). Genome-wide analysis has revealed approximately 50 DnaJ/HSP40 family members in humans, although the exact number remains unclear (Qiu et al., 2006). In addition to their function as chaperones, HSP40 proteins have been reported to play an important role in cancer biology (Mitra et al., 2009; Sterrenberg et al., 2011). As a notable example of the tumor suppressor function, TID1/DNAJA3 inhibits cell proliferation, induces cancer cell apoptosis, and negatively regulates the migration of cancer cells (Cheng et al., 2005; Kim et al., Rabbit polyclonal to DYKDDDDK Tag 2004; 2005). TIG1 is expressed at high levels in well-differentiated tissues. The decreased expression of TIG1 in cancer tissues suggests that TIG1 might play an important role in suppressing tumor growth. TIG1A and TIG1B exhibit similar cellular activities (Shyu et al., 2016; Tsai et al., 2011;.