Aldo–keto reductase family 1 B10 gene silencing results in growth inhibition of colorectal cancer cells: Implication for cancer intervention

Abstract

Aldo-keto reductase family 1 B10 (AKR1B10), a member of aldoketo reductase superfamily, is overexpressed in human hepatocellular carcinoma, lung squamous cell carcinoma and lung adenocarcinoma. Our previous study had demonstrated that the ectopic expression of AKR1B10 in 293T cells promotes cell proliferation. To evaluate its potential as a target for cancer intervention, in the current study we knocked down AKR1B10 expression in HCT-8 cells derived from a colorectal carcinoma, using chemically synthesized small interfering RNA (siRNA). The siRNA 1, targeted to encoding region, downregulated AKR1B10 expression by more than 60%, and siRNA 2, targeted to 3 0 untranslational region, reduced AKR1B10 expression by more than 95%. AKR1B10 silencing resulted in approximately a 50% decrease in cell growth rate and nearly 40% suppression of DNA synthesis. More importantly, AKR1B10 downregulation significantly reduced focus formation rate and colony size in semisolid culture, indicating the critical role of AKR1B10 in HCT-8 cell proliferation. Recombinant AKR1B10 protein showed strong enzymatic activity to acrolein and crotonaldehyde, with K m 5 110.1 6 12.2 lM and V max 5 3,122.0 6 64.7 nmol/mg protein/min for acrolein and K m 5 86.7 6 14.3 lM and V max 5 2,647.5 6 132.2 nmol/mg protein/min for crotonaldehyde. AKR1B10 downregulation enhanced the susceptibility of HCT-8 cells to acrolein (25 lM) and crotonaldehyde (50 lM), resulting in rapid oncotic cell death characterized with lactate dehydrogenase efflux and annexin-V staining. These results suggest that AKR1B10 may regulate cell proliferation and cellular response to additional carbonyl stress, thus being a potential target for cancer intervention. ' 2007 Wiley-Liss, Inc.Key words: aldose reductase-like-1; aldo-keto reductase family 1 B10; reactive carbonyls; gene silencing; clonogenic growth Aldo-keto reductase family 1 B10 (AKR1B10, also designated aldose reductase-like-1, ARL-1) is a novel member of aldo-keto reductase (AKR) superfamily, isolated from human hepatocellular carcinoma (HCC). 1 The AKR superfamily is involved in intracellular detoxification, carcinogenesis and cancer therapeutics. 2,3 Enhanced expression of aldose reductase (AR, also referred to as AKR1B1) is recognized in many types of tumors. 1,4,5 Inhibition of AR activity results in cancer cell growth inhibition and susceptibility to carbonyl compounds and chemotherapeutic agents, 6,7 while induction of AR expression leads to tumor cell resistance to anticancer drugs. 8 Therefore, AR inhibitors developed for the treatment of diabetic complications have become potential chemotherapeutic agents for cancers with AR overexpression. 7,9 AR also regulates mitogenic signaling pathways in vascular smooth muscle cells and vascular endothelial cells, controlling cells growth. 10,11 AKR1B10 shows 71% amino acid sequence identity to AR. 1 Unlike the ubiquitous expression of AR, the AKR1B10 gene is primarily expressed in the small intestine and colon, with lower levels in the liver, thymus, prostate and testes. ...

The Aldo-Keto Reductase Superfamily and its Role in Drug Metabolism and Detoxification

“…The AKR1B10 protein is strongly overexpressed in lung and hepatic carcinomas (squamous cell and adenocarcinomas) (Fukumoto et al, 2005;Cao et al, 1998), as well as in colorectal and uterine cancers (Yoshitake et al, 2007). It has been shown that silencing of AKR1B10 gene using siRNA results in growth inhibition and reduced foci formation rate and colony size of colorectal cancer cells, indicating that AKR1B10 plays a critical role in cancer cell proliferation (Yan et al, 2007). The mitogenic role of AKR1B10 may be related to the depletion of retinoic acid (due to excessive AKR1B10 activity) and subsequent loss of cell differentiation and cancer development (Gallego et al, 2007).…”

“…The AKR1B10 gene has been found induced by cigarette smoke condensate in human oral cells (Nagaraj et al, 2006). Because the enzyme shows high catalytic activity with aldehydes in cigarette smoke such as acrolein and crotonaldehyde (Yan et al, 2007), it is likely that, like aldose reductase, AKR1B10 protective against electrophilic injury. In addition, AKR1B10 appears to regulate biosynthesis of fatty acids through association with a rate-limiting enzyme of de novo synthetic pathway acetyl-CoA carboxylase-α (Ma et al, 2008), however, the physiological significance of this role of AKR1B10 needs to be explored further.…”

Inhibitory effects of polyphenols isolated from Rhus verniciflua on Aldo-keto reductase family 1 B10

“…Thus, an increase in AKR1B10 activity seriously inhibits retinoic acid synthesis, which can be associated with subsequent loss of cell differentiation and cancer development (7). Recent work showed that down-regulation of the AKR1B10 gene using siRNA promoted cell death in colorectal cancer cells through enhanced cytotoxicity of reactive carbonyls produced from lipid peroxidation (8). In other studies, inhibition of AKR1B10 resulted in disruption of lipid synthesis, mitochondrial function and oxidative status, all of which are involved in important cell survival mechanisms (9, 10).…”

“…It requires, however, further mechanistic study because knowing the mechanism would allow the development of clinical drugs without unwanted side effects. Interestingly, AKR1B1 and AKR1B10 show about 71% homology in their amino acid sequences (15), and also show similar substrate specificity towards several endogenous substrates, such as retinals (2), phospholipid aldehydes (16), and acrolein (8). For this reason, selective ARIs might also be inhibitors for AKR1B10, resulting in inhibition in certain types of cancer.…”

Heat Shock Protein 90-α Mediates Aldo-Keto Reductase 1B10 (AKR1B10) Protein Secretion through Secretory Lysosomes

“…This protein is primarily expressed in the human colon and small intestine but overexpressed in breast cancer, hepatocellular carcinoma, non-small cell lung carcinoma, and cervical and endometrial cancers (1)(2)(3)(4). AKR1B10 may be implicated in cancer development and progression by activating procarcinogen polycyclic aromatic hydrocarbon in cigarette smoke and the environment (5), regulating cellular retinoic acid levels (6 -8), mediating fatty acid synthesis (9,10), and detoxifying cytotoxic carbonyl compounds (11)(12)(13)(14)(15)(16)(17) and therapeutic drugs (18,19). Recent studies have demonstrated that AKR1B10 expressed in the intestinal epithelium and cultured cancer cells is secreted through a lysosome-mediated nonclassical protein secretion pathway (20), indicating its detoxicating and/or paracrine role locally in the intestine and in distant organs.…”