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Ref Type | Journal Article | ||||||||||||
PMID | (18692501) | ||||||||||||
Authors | Shibata T, Kokubu A, Gotoh M, Ojima H, Ohta T, Yamamoto M, Hirohashi S | ||||||||||||
Title | Genetic alteration of Keap1 confers constitutive Nrf2 activation and resistance to chemotherapy in gallbladder cancer. | ||||||||||||
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Abstract Text | Biliary tract cancer (BTC) is a highly malignant tumor, and identification of effective therapeutic targets to improve prognosis is urgently required. Oncogenic activation of survival genes is important for cancer cells to overcome oxidative stresses induced by their microenvironments that include chronic inflammation or exposure to anticancer drugs. We attempted to examine whether deregulation of Nrf2, a master transcriptional factor of various cytoprotective genes against oxidative stress, plays a role in the carcinogenesis of BTC.We screened genetic alteration of Keap1, a negative regulator of Nrf2, in BTC including tumors originated from gallbladder and extra- and intrahepatic bile ducts. Functional analysis of cancer-related mutant Keap1 in Nrf2 repression and the association between Nrf2 activation and resistance to 5-fluorouracil (5-FU) were investigated.Recurrent (in 1/11 cell lines and 6/53 primary tumors) Keap1 gene alterations were observed in BTC and were especially frequent (4/13, 30.7%) in gallbladder cancer (GBC). These alterations led to a considerable loss of Nrf2 repression activity, caused constitutive activation of Nrf2, and promoted cell proliferation. Down-regulation of Nrf2 activity by either Keap1 complementation or Nrf2 short interference RNA increased sensitivity to 5-FU in Keap1-altered BTC cells.Keap1 mutation occurs frequently in GBC. Aberrant Nrf2 activation provoked by Keap1 alteration is one of the molecular mechanisms for chemotherapeutic resistance in GBC and will be a novel therapeutic target as an enhancer of sensitivity to 5-FU-based regimens. |
Molecular Profile | Treatment Approach |
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Gene Name | Source | Synonyms | Protein Domains | Gene Description | Gene Role |
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Therapy Name | Drugs | Efficacy Evidence | Clinical Trials |
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Drug Name | Trade Name | Synonyms | Drug Classes | Drug Description |
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Gene | Variant | Impact | Protein Effect | Variant Description | Associated with drug Resistance |
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KEAP1 | C249Y | missense | loss of function | KEAP1 C249Y lies within the BACK domain of the Keap1 protein (UniProt.org). C249Y retains interaction with Nrf2 and Cul3 in culture but results in decreased Nrf2 ubiquitination in culture and loss of NRF2-mediated repression compared to wild-type Keap1 in a reporter assay (PMID: 18692501). | |
KEAP1 | G379D | missense | loss of function | KEAP1 G379D lies within Kelch repeat 2 of the Keap1 protein (UniProt.org). G379D retains interaction with Cul3 but results in loss of interaction with Nrf2 and decreased Nrf2 ubiquitination in culture, loss of NRF2-mediated repression compared to wild-type Keap1 in a reporter assay (PMID: 18692501), and loss of Tnf-mediated NF-kappaB repression in a reporter assay (PMID: 20600852). | |
KEAP1 | S338L | missense | loss of function | KEAP1 S338L lies within Kelch repeat 1 of the Keap1 protein (UniProt.org). S338L retains interaction with Cul3 but results in loss of interaction with Nrf2 and decreased Nrf2 ubiquitination in culture, loss of NRF2-mediated repression compared to wild-type Keap1 in a reporter assay (PMID: 18692501), and loss of Tnf-mediated NF-kappaB repression in a reporter assay (PMID: 20600852). |
Molecular Profile | Indication/Tumor Type | Response Type | Therapy Name | Approval Status | Evidence Type | Efficacy Evidence | References |
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KEAP1 inact mut | gallbladder cancer | resistant | Fluorouracil | Preclinical | Actionable | In a preclinical study, gallbladder cancer cells harboring KEAP inactivating mutations had increased NRF2 activation and demonstrated resistance to Adrucil (fluorouracil) in culture (PMID: 18692501). | 18692501 |