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1.
Front Oncol ; 11: 772604, 2021.
Article in English | MEDLINE | ID: mdl-34976815

ABSTRACT

BACKGROUND: Homologous recombination deficiency (HRD) is characterized by overall genomic instability and has emerged as an indispensable therapeutic target across various tumor types, particularly in ovarian cancer (OV). Unfortunately, current detection assays are far from perfect for identifying every HRD patient. The purpose of this study was to infer HRD from the landscape of copy number variation (CNV). METHODS: Genome-wide CNV landscape was measured in OV patients from the Australian Ovarian Cancer Study (AOCS) clinical cohort and >10,000 patients across 33 tumor types from The Cancer Genome Atlas (TCGA). HRD-predictive CNVs at subchromosomal resolution were identified through exploratory analysis depicting the CNV landscape of HRD versus non-HRD OV patients and independently validated using TCGA and AOCS cohorts. Gene-level CNVs were further analyzed to explore their potential predictive significance for HRD across tumor types at genetic resolution. RESULTS: At subchromosomal resolution, 8q24.2 amplification and 5q13.2 deletion were predominantly witnessed in HRD patients (both p < 0.0001), whereas 19q12 amplification occurred mainly in non-HRD patients (p < 0.0001), compared with their corresponding counterparts within TCGA-OV. The predictive significance of 8q24.2 amplification (p < 0.0001), 5q13.2 deletion (p = 0.0056), and 19q12 amplification (p = 0.0034) was externally validated within AOCS. Remarkably, pan-cancer analysis confirmed a cross-tumor predictive role of 8q24.2 amplification for HRD (p < 0.0001). Further analysis of CNV in 8q24.2 at genetic resolution revealed that amplifications of the oncogenes, MYC (p = 0.0001) and NDRG1 (p = 0.0004), located on this fragment were also associated with HRD in a pan-cancer manner. CONCLUSIONS: The CNV landscape serves as a generalized predictor of HRD in cancer patients not limited to OV. The detection of CNV at subchromosomal or genetic resolution could aid in the personalized treatment of HRD patients.

2.
Chin Med J (Engl) ; 132(12): 1448-1453, 2019 Jun 20.
Article in English | MEDLINE | ID: mdl-31205103

ABSTRACT

BACKGROUND: There is no absolute consensus for the best time for triggering. The aim of this study was to investigate the effect of different proportion of dominant follicles (PDF) on the human chorionic gonadotropin (HCG) day for the clinical outcomes in patients with polycystic ovary syndrome (PCOS) of different ovarian stimulation protocols. METHODS: A total of 371 cycles of the gonadotropin-releasing hormone (GnRH) agonist long protocol and 347 cycles of GnRH antagonist protocol from January 2014 to December 2016 were included in this retrospective study. Based on the PDF on the day of the HCG administration, the included patients were divided into three groups: Group A (low PDF), PDF <20%; Group B (medium PDF), 20%≤ PDF ≤40%; Group C (high PDF), PDF >40%. The measurements regarding ovarian stimulation characteristics, fertilization rate, top quality embryo rate, clinical pregnancy rate, and ovarian hyperstimualtion syndrome (OHSS) rate were compared in different PDF groups with different protocols. RESULTS: In both the GnRH antagonist protocol and GnRH agonist long protocol, the characteristics such as mean age, anti-Mullerian hormone, antral follicle count (AFC), and body mass index were comparable between groups. The number of oocytes retrieved decreased statistically significantly as the PDF and rate of matured oocytes increased. In the GnRH agonist long protocol, the rate of normally fertilized oocytes was highest in Group A (59.74 ±â€Š31.21 vs. 49.70 ±â€Š37.95, 49.67 ±â€Š36.62; F = 3.743, P = 0.025). There were no significant differences in the rate of top-quality embryos and the clinical pregnancy rate between the groups. The clinical pregnancy rate was similar in the three groups (63.6%, 62.5%, 67.5%, respectively, χ = 0.989, P = 0.911). The moderate and severe OHSS rate increased statistically significantly when the PDF increased, which was highest in group C (1.4%, 3.1%, 6.7%, respectively, χ = 12.014, P = 0.017). In the GnRH antagonist protocol, there were no significant differences in the rate of top-quality embryos, the rate of normally fertilized oocytes, the clinical pregnancy rate, and the moderate and severe OHSS rate between the groups. The clinical pregnancy rate in Group C was higher than that in Group A (57.9% vs. 46.6%, χ = 10.850, P = 0.093). CONCLUSIONS: In the GnRH antagonist protocol, PDF on the HCG day of less than 20% may be unfavorable to the clinical pregnancy rate in PCOS. In the GnRH agonist long protocol, delaying the HCG trigger timing has no good effect on clinical pregnancy and the risk of OHSS might increase in patients with PCOS.


Subject(s)
Embryo Transfer/methods , Fertilization in Vitro/methods , Ovarian Follicle/drug effects , Ovarian Follicle/physiology , Polycystic Ovary Syndrome/drug therapy , Polycystic Ovary Syndrome/physiopathology , Adult , Chorionic Gonadotropin/therapeutic use , Female , Gonadotropin-Releasing Hormone/agonists , Gonadotropin-Releasing Hormone/analogs & derivatives , Gonadotropin-Releasing Hormone/antagonists & inhibitors , Gonadotropin-Releasing Hormone/metabolism , Gonadotropin-Releasing Hormone/therapeutic use , Hormone Antagonists/therapeutic use , Humans , Pregnancy , Pregnancy Rate , Retrospective Studies
3.
J Assist Reprod Genet ; 33(1): 33-8, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26631402

ABSTRACT

PURPOSE: The objective of this retrospective study was to determine whether patients undergoing in vitro fertilization (IVF) benefit from reducing the gamete co-incubation time. METHODS: Patients (n = 570) were enrolled, including 281 patients in the reduced incubation time group (2-h incubation) and 289 patients in the standard IVF group (18-h incubation). RESULTS: The observed outcomes, including the clinical pregnancy rate (CPR), implantation rate (IR), live birth rate (LBR), and miscarriage rate (MR), were similar between the two groups. When the data were divided into two subgroups based on the maternal age (≤30 and >30 years), the rates of top-quality embryos (30.83 vs. 25.89 %; p = 0.028), CPR (66.67 vs. 42.11 %; p = 0.013), and IR (41.90 vs. 31.25 %, p = 0.019) of the 2-h incubation group were significantly higher in the younger subgroup. However, for older patients, only a lower MR (7.59 vs. 20.83 %; p = 0.019) was achieved. Reducing the time of incubation still improved the CPR (OR = 1.993, 95 % CI 1.141-3.480) and MR (OR = 3.173, 95 % CI 1.013-9.936) in the younger and older subgroups, respectively, after it was adjusted for potential confounders. CONCLUSIONS: Reducing incubation time improves the clinical results of IVF, although the LBR is not statistically different between the 2- and 18-h incubation time groups. And the specific clinical outcomes of reducing incubation time varied between the >30-year-old and the ≤30-year-old.


Subject(s)
Fertilization in Vitro , Germ Cells/growth & development , Maternal Age , Pregnancy Rate , Abortion, Spontaneous/epidemiology , Adult , Embryo Implantation , Embryo Transfer/methods , Female , Humans , Live Birth/epidemiology , Pregnancy
4.
J Assist Reprod Genet ; 31(12): 1599-604, 2014 Dec.
Article in English | MEDLINE | ID: mdl-25227692

ABSTRACT

PURPOSE: To explore the optimal timing for hCG triggering by investigating the impact of different proportion of dominant follicles on the oocyte developmental competence. METHODS: One hundred ninety-eight infertile women were divided into three groups according to the proportion of dominant follicles on hCG day: (1) low: <15% (n = 66); (2) middle: 15-27% (n = 66); (3) high: >27% (n = 66). The grouping criteria were the bottom and top tertiles of the proportion of dominant follicles. RESULTS: The gonadotropin dosage, duration and maximum follicle diameter in the low proportion group were lower than those in the middle and high proportion groups. Oocyte maturation and the abnormal fertilization rate in the low proportion group were lower than those in the middle and high proportion groups. The normal fertilization rate did not differ among the three groups. The cleavage rate and number of transferable embryos in the low proportion group were significantly higher than those in the high proportion group. The high-quality embryo rate, implantation rate, and pregnancy rate in the low proportion group were significantly higher than those in the middle and high proportion groups. CONCLUSIONS: A high proportion of dominant follicles are closely associated with impaired oocyte developmental competence and low pregnancy rate. These findings suggest that follicular overgrowth induced by delayed hCG triggering may undermine oocyte developmental competence and the proportion of dominant follicles may be a potential parameters for hCG triggering.


Subject(s)
Chorionic Gonadotropin/administration & dosage , Infertility, Female/therapy , Oocytes/growth & development , Oogenesis , Ovarian Follicle/growth & development , Adult , Embryo Transfer/methods , Female , Fertilization in Vitro , Humans , Infertility, Female/pathology , Ovulation Induction/methods , Pregnancy , Pregnancy Rate
5.
Reprod Biol Endocrinol ; 12: 81, 2014 Aug 20.
Article in English | MEDLINE | ID: mdl-25139161

ABSTRACT

BACKGROUND: Oocyte secreted factors (OSFs), including growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15), play an important role in the process of follicular development and oocyte maturation. Since OSFs are expressed in oocytes and cumulus granulosa cells, the aim of the present study was to explore whether the expression levels of GDF9 and BMP15 mRNAs in cumulus granulosa cells can be used as molecular markers for predicting oocyte developmental potential. METHODS: Cumulus cells of 2426 cumulus-oocyte complexes were collected from 196 female patients who underwent intracytoplasmic sperm injection (ICSI) and were used for mRNA detection on the egg retrieval day. Pearson correlation analysis was used to analyze the correlation between OSF expression and general physiological parameters. Partial correlation analysis was used to analyze the correlation between OSF expression and oocyte developmental potential. Covariance analysis was used to compare OSF expression among different groups. Receiver operating characteristic curves were used to examine the diagnostic value of GDF9 and BMP15 mRNA for predicting pregnancy. RESULTS: The expression levels of GDF9 and BMP15 mRNAs were significantly associated with age, body mass index (BMI), oocyte maturation, normal fertilization, and cleavage rate (P < 0.05). The expression levels of GDF9 and BMP15 mRNAs in the group with high-quality embryos were significantly higher than those in the group without high-quality embryos (P < 0.05). The expression levels of GDF9 and BMP15 mRNAs in the pregnancy group were significantly higher than those in the nonpregnancy group (P < 0.05). The cut-off value of GDF9 mRNA for predicting pregnancy was 4.82, with a sensitivity of 82% and a specificity of 64%. The cut-off value of BMP15 mRNA for predicting pregnancy was 2.60, with a sensitivity of 78% and a specificity of 52%. CONCLUSIONS: The expression levels of GDF9 and BMP15 mRNAs were closely associated with oocyte maturation, fertilization, embryo quality, and pregnancy outcome; therefore, GDF9 and BMP15 mRNAs in cumulus granulosa cells may be considered as new molecular markers for predicting oocyte developmental potential.


Subject(s)
Bone Morphogenetic Protein 15/metabolism , Cumulus Cells/metabolism , Ectogenesis , Growth Differentiation Factor 9/metabolism , Oogenesis , RNA, Messenger/metabolism , Up-Regulation , Adult , Biomarkers/metabolism , Bone Morphogenetic Protein 15/genetics , China/epidemiology , Cumulus Cells/cytology , Embryo Culture Techniques , Female , Growth Differentiation Factor 9/genetics , Humans , In Vitro Oocyte Maturation Techniques , Infertility, Male , Male , Pregnancy , Pregnancy Rate , ROC Curve , Retrospective Studies , Sperm Injections, Intracytoplasmic , Spouses
6.
Zhonghua Fu Chan Ke Za Zhi ; 44(10): 745-9, 2009 Oct.
Article in Chinese | MEDLINE | ID: mdl-20078960

ABSTRACT

OBJECTIVE: This study was designed to investigate the correlationship between plasma metastin and pathogenesis of adolescent women with polycystic ovary syndrome (PCOS). METHODS: From Jan. 2006 to Jun. 2006, 42 PCOS patients including 19 adolescent women and 23 adults with syndrome were treated in Second Affiliated Hospital of Sun Yat-Sen University. According to the range of age, those patients were divided into 19 cases in adolescent group ( 19 years). Meanwhile, 20 adolescent women were matched as controls. Blood samples were collected between day 1 and day 5 of a spontaneous bleeding episode in the PCOS groups and a menstrual cycle of the controls. The levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), free T (FT), dehydroepiandrosterone sulfate (DHEAS), sex hormone-binding globulin (SHBG), insulin, glucose, and metastin were detected from day 1 to day 5 of spontaneous bleeding or withdrawal bleeding by progesterone. On the next day, oral glucose tolerance test (75 g) and insulin release test were performed on those above patients and controls. The area under curve (AUC), the ratio of fasting blood glucose to insulin (GIR) and homeostasis model assessment insulin resistance index (HOMA-IR) were calculated. RESULTS: (1) The level of hormone: the level of LH was in (12 +/- 7) U/L in adult group and (12 +/- 8) U/L in adolescent PCOS group, which were significantly higher than (6 +/- 4) U/L in controls (P < 0.05). The level of FT was (2.3 +/- 1.2) pmol/L in adult group, which was significantly higher than (1.3 +/- 0.8) pmol/L in adolescent group and (1.1 +/- 0.5) pmol/L in control group (P < 0.05). It was observed that the level of (3.1 +/- 2.7)micromol/L in adolescent group was significantly lower than (6.3 +/- 2.7) micromol/L in control group (P < 0.05). Meanwhile, the level of FAI of 5.6 +/- 4.1 in adult group was significantly higher than 3.0 +/- 1.3 in control group (P < 0.05). No significant difference in FSH, T and SHBG levels among three groups were observed (P > 0.05). (2) Metastin and metabolism: Both the levels of fasting blood insulin, 2-hour insulin and AUC of insulin were (13 +/- 7) mU/L, (88 +/- 59) mU/L and (133 +/- 80) mUxL(-1)xmin(-1) in adolescent group, which were significantly higher than (7 +/- 3) mU/L, (57 +/- 29) mU/L and (82 +/- 34) mUxL(-1)xmin(-1) in control group. The fasting blood insulin of (13 +/- 7) mU/L in adolescent group was significantly higher than (9 +/- 5) mU/L in adult group. The level of fasting blood glucose and 2-hour glucose were (5.01 +/- 0.44) mmol/L and (6.48 +/- 1.16) mmol/L in adult group, which were significantly higher than (4.68 +/- 0.29) mmol/L and (5.44 +/- 0.83) mmol/L in control group and (4.67 +/- 0.30) mmol/L and (5.93 +/- 1.44) mmol/L in adolescent group. The glucose AUC of (9.99 +/- 1.85) mmolxL(-1)xmin(-1) in adult group was significantly higher than (8.42 +/- 1.53) mmolxL(-1)xmin(-1) in control group (P < 0.05). HOMA-IR of 2.6 +/- 2.0 in adolescent group was significantly higher than 1.4 +/- 0.7 in control group. GIR of 10 +/- 8 in adolescent group was significantly lower than 16 +/- 10 in control group (P < 0.05). The metastin level of (0.25 +/- 0.19) pmol/L in adolescent group and (0.29 +/- 0.29) pmol/L in adult group were all significantly higher than (0.18 +/- 0.23) pmol/L in control group (PPh glucose were observed (r = 0.256, 0.286 and 0.267. P = 0.044, 0.025 and 0.043). CONCLUSIONS: The expression of metastin in adolescent PCOS women was significantly higher that of normal adolescent women. The increased level of metastin might be associated with pathogenesis of adolescent women with PCOS.


Subject(s)
Kisspeptins , Polycystic Ovary Syndrome , Adolescent , Blood Glucose/metabolism , Female , Follicle Stimulating Hormone/blood , Humans , Obesity/blood
7.
Zhonghua Fu Chan Ke Za Zhi ; 42(8): 546-50, 2007 Aug.
Article in Chinese | MEDLINE | ID: mdl-17983495

ABSTRACT

OBJECTIVE: To investigate the effects of gonadotropin releasing hormone agonist (GnRH-a) and antagonist (GnRH-ant) on cyclophosphamide (CTX)-induced ovarian damage in rats. METHODS: Seventy-two Sprague-Dawley female rats were divided randomly into six groups, which received normal saline (NS), CTX, GnRH-a + NS, GnRH-a + CTX, GnRH-ant + NS, and GnRH-ant + CTX respectively. Levels of serum follicle-stimulating hormone (FSH), luteinizing hormone (LH) and estradiol (E(2)) were measured successively by the enzyme-linked immunosorbent assay method, and half of the rats were killed in the first week and between the fourth and the fifth week after stop of medication, respectively to compare the weight of the ovaries and the number of the primordial follicles and the growth follicles. RESULTS: (1) Throughout experiment, the serum levels of FSH, LH and E(2) of the control group fluctuated slightly, while those in the CTX group kept rising. During medication treatment, compared with the control group [(118 +/- 16) microg/L, (350 +/- 35) microg/L] and the CTX group [(113 +/- 15) microg/L, (289 +/- 42) microg/L], the concentrations of LH [(42 +/- 8) - (47 +/- 7) microg/L, (31 +/- 5) - (36 +/- 7) microg/L] and FSH [(124 +/- 45) - (136 +/- 32) microg/L, (178 +/- 54) - (198 +/- 27) microg/L] in the GnRH-a groups and the GnRH-ant groups were maintained at low levels significantly and the levels of LH in the GnRH-ant groups were significantly lower than that in the GnRH-a groups, but the levels of FSH in the GnRH-ant groups were significantly higher than that in the GnRH-a groups (P < 0.05); and extremely different from the GnRH-a groups [(0.98 +/- 0.18) - (1.46 +/- 0.22) ng/L], the level of E(2) of the GnRH-ant groups [(3.58 +/- 0.43) - (3.98 +/- 0.74) ng/L] did not significantly decrease (P < 0.01). After stop of therapy, the concentrations of LH, FSH and E(2) in the GnRH-a groups and the GnRH-ant + NS group rose gradually and were similar to the levels of the control group (P > 0.05), but the levels of FSH, LH and E(2) of the GnRH-ant + CTX group rose obviously and were similar to the levels of the CTX group, especially the FSH , and the levels of LH and FSH of the GnRH-ant + CTX group [(156 +/- 12) microg/L, (520 +/- 44) microg/L] and the CTX group [(178 +/- 18) microg/L, (546 +/- 36) microg/L] were significantly higher than that of the other four groups [(121 +/- 15) - (132 +/- 13) microg/L, (335 +/- 35) - (359 +/- 26) microg/L] at the 4(th) - 5(th) week after stop of treatment (P < 0.05). (2) At the 1(st) week after stopping therapy, the GnRH-a + NS group [(12 +/- 5) mg/100 g]and the GnRH-a + CTX group [(18 +/- 8) mg/100 g] had the lowest weight of ovaries which was significantly different from the other groups [(30 +/- 9) - (37 +/- 8) mg/100 g, P < 0.05]. At the 4(th) - 5(th) week after stopping therapy, the GnRH-ant + CTX group [(22 +/- 6) mg/100 g] and the CTX group [(20 +/- 4) mg/100 g] had the lowest weight of ovaries which were significantly different from the other groups [(29 +/- 5) - (31 +/- 9) mg/100 g, P < 0.05]. (3) At the 1(st) week after stopping therapy, there were the largest number of primordial follicles [(824 +/- 45), (689 +/- 39)] and the lowest number of growth follicles [(15 +/- 1), (21 +/- 3)] in the GnRH-a + NS group and the GnRH-a + CTX group, but there were the lowest number of primordial follicles [(255 +/- 24), (343 +/- 29)] and the largest number of growth follicles [(110 +/- 21), (87 +/- 17)] in the GnRH-ant + CTX group and the CTX group. At the 4(th) - 5(th) week after stopping therapy, the number of growth follicles in the GnRH-a + NS group (58 +/- 11) and the GnRH-a + CTX group (56 +/- 16) recovered to almost the level of the control group (57 +/- 9, P > 0.05), but the number of all kinds of follicles declined significantly in the GnRH-ant + CTX group [(195 +/- 15), (36 +/- 12)] and the CTX group [(212 +/- 11), (36 +/- 9)] compared to the other four groups [(302 +/- 15) - (690 +/- 43), (44 +/- 12) - (58 +/- 11), P < 0.05]. CONCLUSION: In rat model, GnRH-a prevents the ovarian function damage induced by CTX, but GnRH-ant does not show similar protective effect.


Subject(s)
Biomarkers/blood , Gonadotropin-Releasing Hormone/agonists , Gonadotropin-Releasing Hormone/antagonists & inhibitors , Ovary/physiopathology , Animals , Cyclophosphamide , Estradiol/blood , Female , Follicle Stimulating Hormone/blood , Luteinizing Hormone/blood , Ovarian Follicle/drug effects , Ovarian Follicle/physiopathology , Ovary/drug effects , Pituitary Gland/drug effects , Pituitary Gland/physiopathology , Random Allocation , Rats , Rats, Sprague-Dawley
8.
Nan Fang Yi Ke Da Xue Xue Bao ; 27(11): 1714-7, 2007 Nov.
Article in Chinese | MEDLINE | ID: mdl-18024297

ABSTRACT

OBJECTIVE: To investigate ovarian follicular damage induced by chemotherapeutic agents and gonadotropin- releasing hormone receptor (GnRHR) expression in the damaged ovaries in rats. METHODS: Two groups of adult SD rats were subjected to intraperitoneal injection of a single-dose cyclophosphamide and saline, respectively, and 8 weeks later, the ovaries were taken for observing the ovarian damages. The distribution of GnRHR was detected with immunohistochemistry, and RT-PCR was used to determine the expression of GnRHR mRNA in the rat ovaries. RESULTS: Massive primordial follicular loss occurred in the ovaries of rats exposed to cyclophosphamide with also evident stromal ovarian blood vessel damages and focal fibrosis. Both the protein and mRNA expressions of GnRHR were detected in normal rat ovaries, but in rats exposed to cyclophosphamide, the expressions were significantly lowered in the ovaries (P<0.05). CONCLUSION: Low-level GnRHR expressions in the ovaries of rats with cyclophosphamide exposure suggest microenvironment disturbances in the damaged rat ovaries in advanced stage of chemotherapy.


Subject(s)
Cyclophosphamide/adverse effects , Ovary/pathology , Receptors, LHRH/metabolism , Animals , Female , Humans , Ovary/drug effects , Ovary/metabolism , Rats , Rats, Sprague-Dawley
9.
Nan Fang Yi Ke Da Xue Xue Bao ; 27(10): 1476-9, 2007 Oct.
Article in Chinese | MEDLINE | ID: mdl-17959517

ABSTRACT

OBJECTIVE: To investigate the possible pathways for ovarian injury after administration of cyclophosphamide in rats. METHODS: Adult SD rats received a single injection of saline vehicle or chemotherapeutic agent cyclophosphamide, and 8 weeks later, the ovaries were removed, fixed and serially sectioned for pathological examination and ovarian follicle counting. The expression of stem cell factor (SCF) protein was evaluated by immunohistochemistry and immunoreactive score, and SCF mRNA expression determined by RT-PCR in rat ovaries. RESULTS: Cyclophosphamide had a detrimental effect on ovarian stromal function and lead to primordial follicle loss. Immunoreactive SCF antigens were expressed on the oocytes in the primordial and primary follicles of rat ovaries, and also in the granulosa cells of the secondary follicles and early antral follicles. There was a higher granulosa SCF, lower oocyte SCF and higher SCF mRNA level in the ovaries of the rats exposed to cyclophosphamide as compared with those in control rat ovaries (P <0.05). CONCLUSION: Altered SCF expression in the ovaries of rats exposed to cyclophosphamide can be helpful for understanding the mechanisms for chemotherapeutic drug-induced ovarian damage.


Subject(s)
Cyclophosphamide/adverse effects , Gene Expression/drug effects , Ovary/drug effects , Ovary/metabolism , Stem Cell Factor/genetics , Animals , Female , Granulosa Cells/drug effects , Granulosa Cells/metabolism , Oocytes/drug effects , Oocytes/metabolism , Ovary/cytology , Ovary/injuries , Rats , Rats, Sprague-Dawley , Stem Cell Factor/metabolism
10.
Basic Clin Pharmacol Toxicol ; 94(4): 191-200, 2004 Apr.
Article in English | MEDLINE | ID: mdl-15078344

ABSTRACT

It has been shown that large doses of acetaminophen can result in increased degradation of the hepatic cytochrome P450 (CYP) enzymes in vivo; however, the proteolytic pathways have not been identified. We found that incubating transfected HepG2 cells that express CYP3A4 or a reconstituted microsomal model containing human liver microsomes and cytosol, high concentrations of acetaminophen could induce a dose- and time-dependent degradation of CYP3A4. In the microsomal model the degradation could be blocked and augmented by the presence of catalase and superoxide dismutase, respectively. Tocopherol could also protect against the acetaminophen-induced degradation. However, lipid peroxidation assays showed no significant increases in lipid peroxidation products nor was there any protection by propyl gallate. Protease and proteasome inhibitors showed that the proteolytic process was mainly (85%) mediated by the lysosomal pathway, whereas a minor portion (15%) of the degradation was mediated by the proteasomal pathway. Both pepstatin A and anti-cathepsin D neutralizing antibody decreased acetaminophen-induced degradation of CYP3A4 in microsomal model systems. Pepstatin A also blocked the acetaminophen-induced degradation of the CYP3A4 in a transfected HepG2 cell line. Incubating the 3A4 cells in the presence of acetaminophen also increased cathepsin D content and activity. The lysosomal pathway, mainly mediated by cathepsin D, appears to be the major proteolytic pathway involved in the degradation of the P450 enzymes induced by toxic doses of acetaminophen.


Subject(s)
Acetaminophen/toxicity , Analgesics, Non-Narcotic/toxicity , Cytochrome P-450 Enzyme System/metabolism , Peptide Hydrolases/metabolism , Antioxidants/metabolism , Catalase/metabolism , Cell Line , Cytochrome P-450 CYP3A , Cytochrome P-450 Enzyme System/biosynthesis , Dose-Response Relationship, Drug , Humans , Immunoblotting , In Vitro Techniques , Lipid Peroxidation/drug effects , Microsomes, Liver/enzymology , Superoxide Dismutase/metabolism , Time Factors
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