Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.3.44 (P-glycoprotein)
 13,344 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Indole-3-carbinol (I3C) is produced by members of the family Cruciferae, and particularly members of the genus Brassica (e.g., cabbage, radishes, cauliflower, broccoli, Brussels sprouts, and daikon). Under acidic conditions, 13C is converted to a series of oligomeric products (among which 3,3'-diindolylmethane is a major component) thought to be responsible for its biological effects in vivo. In vitro, 13C has been shown to suppress the proliferation of various tumor cells including breast cancer, prostate cancer, endometrial cancer, colon cancer, and leukemic cells; induce G1/S arrest of the cell cycle, and induce apoptosis. The cell cycle arrest involves downregulation of cyclin D1, cyclin E, cyclin- dependent kinase (CDK)2, CDK4, and CDK6 and upregulation of p15, p21, and p27. Apoptosis by I3C involves downregulation antiapoptotic gene products, including Bcl-2, Bcl-xL, survivin, inhibitor-of-apoptosis protein (IAP), X chromosome-linked IAP (XIAP), and Fas-associated death domain protein-like interleukin-1-beta-converting enzyme inhibitory protein (FLIP); upregulation of proapoptotic protein Bax; release of micochondrial cytochrome C; and activation of caspase-9 and caspase-3. This agent inhibits the activation of various transcription factors including nuclear factor-kappaB, SP1, estrogen receptor, androgen receptor and nuclear factor-E2-related factor 2 (Nrf2). This indole potentiates the effects of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) through induction of death receptors and synergises with chemotherapeutic agents through downregulation of P-glycoprotein (P-gp). In vivo, I3C was found to be a potent chemopreventive agent for hormonal-dependent cancers such as breast and cervical cancer. These effects are mediated through its ability to induce apoptosis, inhibit DNA-carcinogen adduct formation, and suppress free-radical production, stimulate 2-hydroxylation of estradiol, inhibit invasion and angiogenesis. Numerous studies have indicated that I3C also has a strong hepatoprotective activity against various carcinogens. Initial clinical trials in women have shown that I3C is a promising agent against breast and cervical cancers.
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PMID:Molecular targets and anticancer potential of indole-3-carbinol and its derivatives. 1608 11

Taxanes are important drugs in the treatment of ovarian and other cancers, but their efficacy is limited by intrinsic and acquired drug resistance. Expression of the multidrug transporter P-glycoprotein, encoded by the MDR1 (ABCB1) gene, is one of the causes of clinical drug resistance to taxanes. To study the mechanisms of MDR1 activation related to taxanes, we established 11 multidrug-resistant variants from six ovarian cancer cell lines by continuous exposure to either paclitaxel or docetaxel. We profiled gene expression and gene copy number alterations in these cell lines using cDNA microarrays and identified a cluster of genes coactivated with MDR1 in 7q21.11-13. Regional activation was evident in nine resistant variants displaying a coexpression pattern of up to 22 genes over an 8-Mb area, including SRI, MGC4175, CLDN12, CROT, and CDK6. In six of these variants, regional activation was driven by gene copy number alterations, with low-level gains or high-level amplifications spanning the involved region. However, three variants displayed regional increases in gene expression even without concomitant gene copy number changes. These results suggest that regional gene activation may be a fundamental mechanism for acquired drug resistance, with or without changes in gene dosage. In addition to numerical and structural chromosomal changes driven by genome instability in cancer cells, other mechanisms might be involved in MDR1 regional activation, such as chromatin remodeling and DNA or histone modifications of the 7q21 region.
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PMID:Regional activation of chromosomal arm 7q with and without gene amplification in taxane-selected human ovarian cancer cell lines. 1638 45

Multidrug resistance mediated by the drug efflux protein, P-glycoprotein (P-gp), is one of the principal mechanisms by which tumor cells escape the cell death induced by chemotherapeutic agents. In our previous study, we demonstrated that KBH-A42 [N-hydroxy-3-(2-oxo-1-(3-phenylpropyl)-1,2,5,6-tetrahydropyridin-3-yl)propanamide], a synthetic histone deacetylase inhibitor, effectively inhibited the growth of several human cancer cell lines. In this study, we attempted to determine whether KBH-A42 was also capable of inhibiting the growth of multidrug-resistant cells. Doxorubicin dose-dependently inhibited the growth of P-gp-negative K562 human leukemia cells, but did not show substantial inhibition on the growth of P-gp-positive K562/ADR cells even at 10 microM, the highest concentration of KBH-A42 used, which increased the acetylation of histones in these leukemia cells, dose-dependently and effectively inhibited the cell growth, regardless of the presence of P-gp in the cells. KBH-A42 mediated G0/G1 cell cycle arrest, probably as the result of the down-regulation of CDK2, CDK4 and CDK6 and the up-regulation of p21WAF1. When the expression of p21WAF1 was ablated by a specific siRNA, the inhibition of cell growth by KBH-A42 was partly reduced in both cell lines. In addition to the cell cycle arrest, KBH-A42 also induced apoptosis in these cells, which was accompanied by the activation of caspases, including caspase-9, caspase-8 and caspase-3. The pan-caspase inhibitor, Z-VAD-fmk, partially blocked the cell death induced by KBH-A42. These results indicate that KBH-A42 induces cell cycle arrest and apoptosis via the up-regulation of p21WAF1 and caspase activation, respectively, regardless of the presence of P-gp in the leukemia cells.
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PMID:KBH-A42, a histone deacetylase inhibitor, inhibits the growth of doxorubicin-resistant leukemia cells expressing P-glycoprotein. 2012 23

Effective treatments for primary brain tumors and brain metastases represent a major unmet medical need. Targeting the CDK4/CDK6-cyclin D1-Rb-p16/ink4a pathway using a potent CDK4 and CDK6 kinase inhibitor has potential for treating primary central nervous system tumors such as glioblastoma and some peripheral tumors with high incidence of brain metastases. We compared central nervous system exposures of two orally bioavailable CDK4 and CDK6 inhibitors: abemaciclib, which is currently in advanced clinical development, and palbociclib (IBRANCE; Pfizer), which was recently approved by the U.S. Food and Drug Administration. Abemaciclib antitumor activity was assessed in subcutaneous and orthotopic glioma models alone and in combination with standard of care temozolomide (TMZ). Both inhibitors were substrates for xenobiotic efflux transporters P-glycoprotein and breast cancer resistant protein expressed at the blood-brain barrier. Brain Kp,uu values were less than 0.2 after an equimolar intravenous dose indicative of active efflux but were approximately 10-fold greater for abemaciclib than palbociclib. Kp,uu increased 2.8- and 21-fold, respectively, when similarly dosed in P-gp-deficient mice. Abemaciclib had brain area under the curve (0-24 hours) Kp,uu values of 0.03 in mice and 0.11 in rats after a 30 mg/kg p.o. dose. Orally dosed abemaciclib significantly increased survival in a rat orthotopic U87MG xenograft model compared with vehicle-treated animals, and efficacy coincided with a dose-dependent increase in unbound plasma and brain exposures in excess of the CDK4 and CDK6 Ki values. Abemaciclib increased survival time of intracranial U87MG tumor-bearing rats similar to TMZ, and the combination of abemaciclib and TMZ was additive or greater than additive. These data show that abemaciclib crosses the blood-brain barrier and confirm that both CDK4 and CDK6 inhibitors reach unbound brain levels in rodents that are expected to produce enzyme inhibition; however, abemaciclib brain levels are reached more efficiently at presumably lower doses than palbociclib and are potentially on target for a longer period of time.
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PMID:Brain Exposure of Two Selective Dual CDK4 and CDK6 Inhibitors and the Antitumor Activity of CDK4 and CDK6 Inhibition in Combination with Temozolomide in an Intracranial Glioblastoma Xenograft. 2614 30