Knock-down of hypoxia-induced carbonic anhydrases IX and XII radiosensitizes tumor cells by increasing intracellular acidosis

Doyen, J.; Parks, Scott K.; Marcié, S.; Pouysségur, Jacques; Chiche, Johanna

doi:10.3389/fonc.2012.00199

Cited by 57 publications

(67 citation statements)

References 38 publications

(55 reference statements)

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“…This dependency leads to cancer cell reliance on LAT1 activity to sustain tumoral AA homeostasis, mTORC1 activation, and tumor growth. Previous studies from our laboratory investigated the potential of disrupting different metabolismrelated proteins as therapeutic targets (44)(45)(46)(47). Use of the aggressive LS174 xenograft model in these previous studies underlined the problem of the functional protein redundancy in terms of cancer treatment.…”

Section: Resultsmentioning

confidence: 99%

Genetic Disruption of the Multifunctional CD98/LAT1 Complex Demonstrates the Key Role of Essential Amino Acid Transport in the Control of mTORC1 and Tumor Growth

et al. 2016

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The CD98/LAT1 complex is overexpressed in aggressive human cancers and is thereby described as a potential therapeutic target. This complex promotes tumorigenesis with CD98 (4F2hc) engaging b-integrin signaling while LAT1 (SLC7A5) imports essential amino acids (EAA) and promotes mTORC1 activity. However, it is unclear as to which member of the heterodimer carries the most prevalent protumoral action. To answer this question, we explored the tumoral potential of each member by gene disruption of CD98, LAT1, or both and by inhibition of LAT1 with the selective inhibitor (JPH203) in six human cancer cell lines from colon, lung, and kidney. Each knockout respectively ablated 90% (CD98 KO ) and 100% (LAT1 KO ) of Na þ -independent leucine transport activity. LAT1 KO or JPH203-treated cells presented an amino acid stress response with ATF4, GCN2 activation, mTORC1 inhibition, and severe in vitro and in vivo tumor growth arrest. We show that this severe growth phenotype is independent of the level of expression of CD98 in the six tumor cell lines. Surprisingly, CD98KO cells with only 10% EAA transport activity displayed a normal growth phenotype, with mTORC1 activity and tumor growth rate undistinguishable from wild-type cells. However, CD98KO cells became extremely sensitive to inhibition or genetic disruption of LAT1 (CD98 KO /LAT1 KO ). This finding demonstrates that the tumoral potential of CD98 KO cells is due to residual LAT1 transport activity. Therefore, these findings clearly establish that LAT1 transport activity is the key growthlimiting step of the heterodimer and advocate the pharmacology development of LAT1 transporter inhibitors as a very promising anticancer target. Cancer Res; 76(15);

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Section: Resultsmentioning

confidence: 99%

Genetic Disruption of the Multifunctional CD98/LAT1 Complex Demonstrates the Key Role of Essential Amino Acid Transport in the Control of mTORC1 and Tumor Growth

et al. 2016

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“…11,32 Thus, CA12 can contribute to cellular alkalinization and intracellular pH homeostasis. Chiche et al 18 and Doyen et al 33 previously found that CA12 suppression decreases tumor cell survival by increasing intracellular acidosis. Power et al 14 found that the CA12 inhibitor 4-aminobenzene sulfonamide decreases lactate levels in hypoxic NP cells, suggesting that CA12 can counteract cellular acidosis.…”

Section: Ca12 Protects Against Disc Degeneration S Chen Et Almentioning

confidence: 99%

PHD/HIF-1 upregulates CA12 to protect against degenerative disc disease: a human sample, in vitro and ex vivo study

Chen

Fang

Wang

et al. 2016

Laboratory Investigation

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Intervertebral disc degeneration is a major cause of low back pain. The nucleus pulposus (NP) is an important intervertebral disc component. Recent studies have shown that carbonic anhydrase 12 (CA12) is a novel NP marker. However, the mechanism by which CA12 is regulated and its physiological function are unclear. In our study, CA12, hypoxia-inducible factor 1α (HIF-1α) and HIF-2α expression levels were examined in 81 human degenerated NP samples using real-time RT-PCR, immunohistochemistry and western blot. Rat NP cells were cultured in a hypoxic environment, and hypoxia-induced CA12 expression was examined. Rat NP cells were treated with HIF-1α siRNA or the prolyl hydroxylase (PHD) inhibitor dimethyloxalylglycine (DMOG) to evaluate the role of PHD/HIF-1 in regulating CA12 expression. Rat NP cells were treated with CA12 siRNA to determine the function of CA12. A rat ex vivo model was established to confirm that PHD, HIF-1, and CA12 have important roles in disc degeneration. We found that CA12 was significantly downregulated in degenerated human NP samples at the mRNA and protein levels. CA12 expression sharply increased by~30-fold in response to hypoxia. The expression of HIF-1α, but not HIF-2α, also decreased in degenerated human NP samples and was positively correlated with CA12 expression. HIF-1α knockdown under hypoxia reduced the CA12 mRNA and protein expression levels. DMOG treatment increased HIF-1α and CA12 expression. CA12 knockdown significantly inhibited anabolic protein expression, whereas catabolic enzymes remained unchanged. The ex vivo experiments supported our in vitro studies of the role of PHD/HIF-1/CA12. In conclusion, CA12 is downregulated in degenerated NPs, and its expression may be regulated by the PHD/HIF-1 axis. Decreased CA12 expression may lead to decreased extracellular matrix synthesis, which contributes to degenerative disc disease progression. Low back pain (LBP) is one of the most common clinical complaints. Approximately 80% of people experience LBP during their lifespan, 1 and this condition causes severe pain, disability, and heavy economic burden. Among the various causes of LBP, intervertebral disc degeneration is thought to be one of the most central causes. 2,3 The intervertebral disc consists of the central proteoglycan-rich nucleus pulposus (NP) and the surrounding fibrocartilaginous annulus fibrosis (AF) with good restoration of strength, ROM, and function. The highly absorptive proteoglycans in the NP absorb stress and maintain the structural and functional integrity of the spine. 4,5 An imbalance between NP extracellular matrix (ECM) anabolism and catabolism leads to degenerative disc disease. 6 NP cell aging or changes to the microenvironment can lead to decreased normal ECM protein synthesis (mainly type II collagen and aggrecan) and increased synthesis of ECM proteins related to fibrosis, such as type I collagen. 6 Inflammatory cytokines, such as interleukin-1β and tumor necrosis factor-α, stimulate the expression of ECM catabolic enzymes, such as matrix metallopr...

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“…This is demonstrated in studies using 3D tumor cell spheroids, where CA IX minimizes the intracellular pH gradient and increases the extracellular pH gradient from the spheroid surface to the spheroid core (Swietach et al 2009(Swietach et al , 2010. Moreover, CA IX-deficient tumor cells show an inability to adapt to acidosis in vitro, reduced capacity to grow in tumor xenografts in vivo, and increased susceptibility to radiation treatment (Chiche et al 2009;Doyen et al 2012). …”

Section: Ca IX and Ph Regulation Through The Bicarbonate Transport Mementioning

confidence: 91%

Carbonic Anhydrase IX: From Biology to Therapy

Pastoreková¹,

Supuran²

2013

Hypoxia and Cancer

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Growing tumor tissues develop a stressful microenvironment characterized by hypoxia and acidosis. Tumor cells can survive these stresses via induction of adaptive transcriptional changes mediated primarily by the hypoxia-inducible factor (HIF), and via stimulation of ion transport machinery maintaining normal intracellular pH. In addition, through these adaptive responses tumor cells acquire new features endowing them with selective advantage in migration, invasion, metastasis, and resistance to therapy. Carbonic anhydrase IX (CA IX), a highly active cancer-related carbonic anhydrase isoform, is linked to both hypoxia, as a direct transcriptional target of HIF, and acidosis, as a component of mechanisms that facilitate ion transport across the plasma membrane and thereby counteract the intracellular accumulation of acidic metabolic products. Expression pattern of CA IX in human tumors reflects the activation of the HIF pathway by physiologic hypoxia, genetic defects, and/or oncogenic events. Moreover, CA IX plays an active role not only in pH regulation but also in cell migration and invasion. Thus, it is often exploited and/or investigated as an intrinsic marker of hypoxia, a prognostic indicator, and a therapeutic target for antibodies or inhibitors of the enzyme activity. It is believed that these CA IXtargeted therapeutic approaches can mediate the selective killing of CA IX-positive cells or sensitize tumor cells to conventional treatment modalities. In addition, both

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Knock-down of hypoxia-induced carbonic anhydrases IX and XII radiosensitizes tumor cells by increasing intracellular acidosis

Cited by 57 publications

References 38 publications

Genetic Disruption of the Multifunctional CD98/LAT1 Complex Demonstrates the Key Role of Essential Amino Acid Transport in the Control of mTORC1 and Tumor Growth

Genetic Disruption of the Multifunctional CD98/LAT1 Complex Demonstrates the Key Role of Essential Amino Acid Transport in the Control of mTORC1 and Tumor Growth

PHD/HIF-1 upregulates CA12 to protect against degenerative disc disease: a human sample, in vitro and ex vivo study

Carbonic Anhydrase IX: From Biology to Therapy

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