Abstract P6-21-03: Phase I trial of intratumoral (IT) administration of a NIS-expressing derivative manufactured from a genetically engineered strain of measles virus (MV)

Background: The live attenuated non-pathogenic Edmonston MV vaccine strain has advantages as an oncolytic platform given its tumor specificity, potent bystander effect, and ability to be engineered and retargeted. MV-NIS expresses the human thyroidal sodium-iodide symporter (NIS) and is selectively oncolytic, entering tumor cells through CD46 (overexpressed on many cancers, including breast cancer of all subtypes) and Nectin-4. NIS expression in MV-NIS infected cells permits noninvasive monitoring of virus spread by SPECT-CT imaging of Tc-99m pertechnetate or I-123 uptake.

Methods: NCT01846091 is a standard 3+3 phase I trial of a single IT administration of MV-NIS in pts with recurrent/metastatic squamous cell carcinoma of the head and neck (SCCHN) or metastatic breast cancer (MBC). Primary objectives are (a) safety and tolerability and (b) maximally tolerated single dose. The secondary clinical objective is to preliminarily assess antitumor efficacy at and away from the MV injection site. Key eligibility criteria were: absence of standard therapy with life prolonging intent; at least one lesion >1 cm amenable to percutaneous injection; and no impending visceral crisis. MV-NIS was administered on D1 with mandatory SPECT-CT at baseline (BL) and on D3&D8; repeat SPECT-CT on D15&D21 if the prior result was positive; mandatory tumor biopsies on D3&D21; optional tumor biopsies on D8&D15; assessments for viremia and viral shedding at BL and on D3,D8,D15,D21; and standard imaging for restaging at BL,D21,W6,W12.

Results: Accrual completed with 12 evaluable pts (6 SCCHN and 6 MBC) at 3 dose levels (108, 3x108, 109 TCID50). The MBC group included 5 HR+/HER2- pts and 1 pt with mixed HR+/HER2- and HR+/HER2+ disease. 5 pts had evidence of disease progression prior to study participation. No dose limiting toxicities were observed among the MBC pts; AEs possibly related to MV-NIS in this group were gr2 fatigue, gr1 flu-like illness, gr2 lymphopenia (all n=1). No SCCHN responses were observed. Best response for the MBC pts was: stable disease (SD) >6 wks, n=4; clinical response, n=1; progression, n=1. One MBC pt with SD for 12 wks had positive SPECT/CT imaging at and away from the injection site on D3&D8 and was the only pt seronegative for measles IgG antibodies prior to MV-NIS exposure. The MBC pt who responded after initial MV-NIS exposure was the only pt with low viral RNA in blood (D3); she received additional doses at W9&W13 without toxicity through an expanded access protocol exemption and had disease progression by W19. No viral shedding was detected from mouth rinse or urine in any pt. MV was detected in tumor samples from all pts treated at the highest dose level. Additional blood and tissue analyses are in progress.

Conclusion: These results demonstrate the safety of IT MV-NIS administration, provide early evidence of biologic activity in MBC, and support the possibility of viral replication in tumors remote from the IT injection site. A MV strain encoding the immunomodulatory neutrophil activating protein transgene has been constructed (MV-s-NAP) with preclinical evidence of improved antitumor activity and immunogenicity. The phase I MV-s-NAP trial will start recruitment in Fall 2018.

Citation Format: Liu MC, Peng K-W, Federspiel MJ, Russell SJ, Brunton BA, Zhou Y, Packiriswamy N, Hubbard JM, Loprinzi CL, Peethambaram PP, Ruddy KJ, Allred JB, Galanis E, Okuno SH. Phase I trial of intratumoral (IT) administration of a NIS-expressing derivative manufactured from a genetically engineered strain of measles virus (MV) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-21-03.

Facet joint signal change on MRI at levels of acute/subacute lumbar compression fractures

BACKGROUND AND PURPOSE

The prevalence of facet joint signal change in acute/subacute lumbar vertebral body compression fractures is unknown. We hypothesized that facet joint signal change on MR imaging is more common in facet joints associated with an acute/subacute lumbar compression fracture than those associated with normal vertebral bodies or ones that have a chronic compression fracture.

MATERIALS AND METHODS

Three neuroradiologists and a neuroradiology fellow retrospectively graded facet joint inflammatory change on MR imaging in 900 facet joints in 75 patients with at least 1 painful osteoporotic lumbar compression fracture. Facet joint signal change was assessed on T2-weighted images with chemical fat-saturation, STIR images, and/or gadolinium-enhanced T1-weighted images with chemical fat-saturation. Each facet joint from the T12/L1 to L5/S1 level was assessed individually. An overall facet joint signal-change score, which is a composite measure of the grade of signal change for all 4 facet joints associated with a given lumbar vertebral level, was devised, and statistical significance was assessed via Wilcoxon rank sum tests.

RESULTS

The overall facet joint signal-change scores were significantly higher at vertebral body levels affected by an acute/subacute compression fracture compared with control levels, which were associated with either normal bodies or chronic compression fractures.

CONCLUSIONS

Our findings suggest an association between facet joint signal change on MR imaging and acute/subacute lumbar vertebral body compression fractures.

Abstract P1-12-06: N0937 (Alliance): Preliminary results of a phase II clinical trial of cisplatin and the novel agent brostallicin in patients with metastatic triple negative breast cancer (mTNBC)

Background: TNBC is characterized by unique molecular profiles, aggressive behavior, poor prognosis and lack of targeted therapies. Brostallicin is a novel synthetic compound from the class of DNA minor groove binding (MGB) anti-cancer agents, making it a logical agent to evaluate in the setting of TNBC. It retains activity in cancer cells resistant to alkylating agents, topoisomerase I inhibitors and is fully active against DNA-mismatch repair deficient tumor cells. Preclinical models using cell lines demonstrate that cells expressing relatively high glutathione/glutathione S-transferase (GSH/GST) levels are more susceptible to brostallicin's antitumor efficacy. Cisplatin administration increases expression of GSH/GST in tumor cells, thus leading to an increased anti-tumor efficacy of brostallicin.

Methods: Phase II cooperative group study in pts with mTNBC (³18 years of age with measurable metastatic disease, ER/PR ≤1%; HER2 negative, who had received 0–4 prior chemotherapy regimens in the metastatic setting; with adequate hematologic, renal and hepatic functions; and no active CNS metastases; prior exposure to cisplatin allowed). Cisplatin on Day 1 followed by brostallicin on Day 2, repeated every 21 days. Aim: efficacy of brostallicin and proof of concept of its mechanism of action in mTNBC. Primary endpoint progression-free survival (PFS) at 3 months with 89% power (0.10 significance level) to detect an absolute difference of 20% (35% vs 55%), based on the median PFS of 60 days in pts with mTNBC from the N0234 trial of erlotinib and gemcitabine as 1st/2nd line. Secondary endpoints include ORR, duration of response (DOR), 6-month PFS, OS and AE profile. Tertiary endpoints include assessment of 1) GSH levels prior to the administration of cisplatin and of brostallicin; and 2) the prevalence of BCRA-1 mutation by IHC in primary or metastatic tumor.

Results: Study closed on 3/28/12 and it accrued 48 pts (median f/u 2.3 mo; 0–15.3); 33 pts are off treatment and 15 pts remain on study; 38 pts evaluable for response, and 43 evaluable for AEs. 50% received therapy as 3rd to 5th line. Median number of cycles 2.5 (off-treatment: 2; on-treatment: 3, range 0–15). There are currently 5 confirmed responses (4 PR and 1 CR); DOR: 2.8–13.3 months. The 6-mo PFS is currently 19.2% (95% CI: 8.9%, 41.3%); the median TTP is 3.0 months (95% CI: 1.7 months, 4.2 months). Current data are premature to determine the primary endpoint (3-mo PFS) but we expect to report such data by November 2012. Current toxicity data: 69.7% G3/4 heme toxicity. Non-heme toxicity G3 (30.2%) and G4 (9.3)% (febrile neutropenia 21%; fatigue G3 14%); and no G5 non-heme AE.

Conclusions: The current preliminary data of this trial show very encouraging activity of this regimen (brostallicin plus cisplatin) in mTNBC. Near 1/3 of pts are still currently receiving therapy, and we expect to provide primary and additional secondary endpoint data at SABCS 2012.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-12-06.

OT3-01-06: A Phase 2 Study Investigating the Safety, Efficacy and Surrogate Biomarkers of Response of 5-Azacitidine (5-AZA) and Entinostat (MS-275) in Patients with Advanced Breast Cancer

Background: Epigenetic alterations in the genome, including abnormal DNA methylation and histone hypoacetylation, initiate and promote cancerous changes via several mechanisms, including inactivation of tumor suppressor genes. Preclinical investigations in breast cancer suggest that use of epigenetic modifiers results in re-expression of aberrantly silenced genes and proteins that represent important therapeutic targets (e.g. estrogen receptor alpha, ER). Combination therapy with a DNA methyltransferase inhibitor (DNMTI) and a histone deacetylase inhibitor (HDACI) has yielded superior ER reexpression and greater restoration of tamoxifen responsiveness than with HDACI alone. We hypothesize that clinically tolerable doses of the DNMTI 5-azacitidine (5-AZA) and the HDACI entinostat may not only effect changes in DNA methylation and gene expression, but also yield objective disease responses in women with advanced breast cancer.

Trial design: This multicenter phase II study (NCT01349959) is enrolling patients with advanced human epidermal growth factor receptor 2 (HER2)-negative breast cancer with triple negative (ER/progesterone receptor [PR]/HER2−negative, Cohort A) or hormone-resistant (Cohort B) disease. Patients will receive 5-AZA 40 mg/m2 subcutaneously days 1–5 and 8–10 and entinostat 7 mg orally days 3 and 10 every 28 days. Because of the potential for re-expression of the ER with epigenetic agents, patients will be offered continuation of 5-AZA and entinostat at progression with the addition of hormonal therapy (investigator discretion). Mandatory tumor biopsies will be performed at baseline and after 8 weeks of therapy to evaluate correlative biomarkers.

Eligibility Criteria: Eligible patients must be ≥ 18 years, have measurable locally advanced/metastatic triple-negative (at least one prior chemotherapy received adjuvant/metastatic setting) or hormone-resistant (must have received two prior hormonal agents and one prior chemotherapy) disease, adequate organ function and ECOG PS ≤ 2.

Specific Aims:

1. Objective response rate (ORR) by RECIST 1.1 criteria.

2. Safety and tolerability

3. Progression-free survival, overall survival and clinical benefit rate.

4. Safety and toxicity data, feasibility and response rate where hormonal therapy is added to the combination under investigation at the time of progressive disease.

5. Pharmacokinetics, cytidine deaminase, changes from baseline of candidate gene methylation and expression in circulating deoxyribonucleic acid (DNA) and malignant tissue.

Statistical Methods:

Using a two-stage three-outcome design to assess the efficacy of the combination, a maximum of 30 patients (requiring 27 evaluable) will be accrued to each cohort unless undue toxicity is encountered for a maximum sample size of 60 patients. The study design tests the null hypothesis that the ORR is at most 5% against the alternative hypothesis that it is at least 20% with a type I error of 4% and power of 90%.

Present and Targeted Accrual: This study has just opened to patient enrollment. We anticipate a rapid accrual of 60 patients within 1 year.br](Funding from Stand Up to Cancer and CTEP).

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT3-01-06.

Pomalidomide (CC4047) plus low dose dexamethasone (Pom/dex) is active and well tolerated in lenalidomide refractory multiple myeloma (MM)

Patients with multiple myeloma progressing on current therapies have limited treatment options. Pomalidomide (CC4047), an immunomodulatory drug, has significant activity in relapsed myeloma and previous studies suggest activity in lenalidomide refractory disease. To better define its efficacy in this group, we treated a cohort of lenalidomide refractory patients. Pomalidomide was given orally (2 mg) daily, continuously in 28-day cycles along with dexamethasone (40 mg) given weekly. Responses were assessed by the International Myeloma Working Group Criteria. Thirty-four patients were enrolled. The best response was very good partial response in 3 (9%), partial response (PR) in 8 (23%), best responses (MR) in 5 (15%), stable disease in 12 (35%) and progressive disease in 6 (18%), for an overall response rate of 47%. Of the 14 patients that were considered high risk, 8 (57%) had responses including 4 PR and 4 MR. The median time to response was 2 months and response duration was 9.1 months, respectively. The median overall survival was 13.9 months. Toxicity was primarily hematologic, with grade 3 or 4 toxicity seen in 18 patients (53%) consisting of anemia (12%), thrombocytopenia (9%) and neutropenia (26%). The combination of pomalidomide and dexamethasone (Pom/dex) is highly active and well tolerated in patients with lenalidomide-refractory myeloma.

Progression-free and overall survival analysis in patients with metastatic melanoma undergoing first- versus second-line therapy

9078

Background: A frequently discussed topic at meetings of oncologists is the question of expected clinical outcomes for patients with metastatic melanoma undergoing 1st vs 2nd line systemic therapy. Differing outcomes in these two patient populations could affect interpretation of non-randomized clinical trials involving both patient populations. Some have suggested superior clinical outcome in patients undergoing 2nd line therapy. As there is little data addressing this issue, we sought to answer the question by comparing the clinical outcomes of patients with metastatic melanoma treated on 1st vs 2nd line therapy across clinical trials conducted at our institution. Methods: Data were collected from 10 phase II clinical trials for patients with stage IV melanoma for which Mayo Clinic was the data center. The 10 trials included three categories of treatments: cytotoxic chemotherapy (4), cancer vaccines (4), and biologic agents (2). In all studies, eligibility criteria required: stage IV melanoma, life expectancy >3 months, reasonable hematology and serum chemistry laboratory results, and an ECOG performance status of ≤2. Cox proportional hazards models were fit to assess the relationship between patients' “therapy” status (1st vs 2nd line) and time to events, both overall survival (OS) and progression free survival (PFS), for each treatment category. Results: We identified 318 unique eligible patients across 10 trials. Removed from the analysis were 55 patients (ocular melanoma and/or metastases involving the central nervous system) leaving 263. Cox proportional hazards results demonstrated no differences in PFS or OS for 1st vs 2nd line patients for either “chemotherapy” or “vaccine” treatment regimens. However, patient treated on “biologic” trials as 1st line therapy appeared to demonstrate a PFS advantage over 2nd line treatments (HR=1.98, p-value=0.02). There was a suggestion of an OS benefit for 1st line patients in this category, however, the relationship was not significant (HR=1.77, p=0.07). Conclusions: The presented data suggest that there is no PFS/OS difference in stage IV melanoma patients receiving 1st vs 2nd line therapy (no PFS/OS advantage to patients treated in 2nd line vs. 1st line).

No significant financial relationships to disclose.

Cytokeratin-19 (CK19) and mammaglobin (MGB1) gene expression in circulating tumor cells (CTCs) from metastatic breast cancer patients enrolled in the NCCTG trials, N0436 and N0437

11095

Background: Biologic characterization of CTCs is increasingly important in determining metastatic breast cancer (MBC) patient (pt) prognosis and treatment prediction. Combined preliminary results from two earlier metastatic BC NCCTG trials, N0234 & N0336, suggested that the change in CTC mammaglobin (MGB1) gene expression between baseline and two cycles of chemotherapy predicted tumor response (p=0.04). The objectives of this study were to 1) determine CTC gene expression of CK19 and MGB1 before, during, and after treatment in N0436 & N0437 and 2) determine associations between baseline and post-treatment gene expression and treatment response. Methods: CTCs were enriched using CD45-depletion from ∼10ml EDTA blood obtained from metastatic BC pts before, after two cycles, and at end of treatment with either first/second-line irinotecan plus cetuximab (N0436) or first-line paclitaxel poliglumex and capecitabine (N0437). CK19 and MGB1 mRNA levels were determined using quantitative RT-PCR in baseline and serial CTC samples of up to 19 pts from N0436 and 40 pts from N0437. The relative gene expressions were normalized to β2-microglobulin and calibrated to healthy blood using the 2-ΔΔCt algorithm; a value of 2 was defined as positive for the respective marker. Results: CK19+ mRNA was detected in 58% of baseline samples from N0436 (11/19) and N0437 (23/40). MGB1+ mRNA was detected in 32% (6/19) and 38% (15/40) of N0436 and N0437 baseline samples, respectively. CK19+ mRNA was detected in 50% (7/14) and 56% (29/52) of N0436 and N0437 serial CTC samples, respectively. MGB1+ mRNA was detected in 29% (4/14) and 27% (14/52) of N0436 and N0437 serial CTC samples, respectively. Of the 66 serial samples, 27% of samples (18/66) had turned positive from baseline for CK19 or MGB1. CK19 mRNA was detected in 85% (33/39) of MGB1+ mRNA samples but their baseline mRNA levels were not correlated. Conclusions: CK19 mRNA was detected in MBC pts with similar frequencies to the CellSearch imaging system. CK19 was detected at a higher frequency than MGB1. In the majority of cases, MGB1 was co-expressed with CK19. Associations between gene expression and treatment response using Chi-Squared analyses and Cox regression models will be presented.

No significant financial relationships to disclose.

NCCTG N0338: effect of docetaxel and carboplatin on VEGF, PGE2, and immune cells in patients with stage II or III breast cancer

Abstract #5110

Background: It has been demonstrated that certain chemotherapeutic drugs such as taxanes increases cyclooxygenase-2 (COX-2) levels. Upregulation of COX-2 may be a resistance mechanism of the tumor, or a method to modulate toxic effects of the agent. COX-2 is associated with less differentiated and more aggressive breast cancers, and the expression may be a prognostic indicator of disease. Studies defining the “true” impact of therapy on COX-2 activity are lacking. Hypothesis: Chemotherapy increases COX-2 function in patients with invasive breast cancer. This leads to increased PGE2, VEGF, and downregulation of immune responses. Objective: Patients with stage II or III breast cancer were enrolled in a phase II preoperative chemotherapy trial of docetaxel and carboplatin administered every two weeks (4 cycles). We evaluated circulating PGE2, VEGF, and immune cell phenotype at diagnosis and after chemotherapy. Results: Fifty seven patients were enrolled in the study and 32 were analyzed in the lab, most of them being infiltrating ductal carcinoma. Four had complete response, 20 had partial response, and 8 were non-responders. Due to low numbers of patients analyzed, statistical significance was not achieved in most instances. Nevertheless, intriguing data has been generated that warrants further investigation. VEGF/PGE2 versus clinical response to chemotherapy: 86% of the patients in whom VEGF levels decrease post chemotherapy were responders compared to 60% in which VEGF remained unchanged or increased slightly. Responders had decreased VEGF levels on average, while the non-responders increased. Interestingly, even with low sample size, if both VEGF and PGE2 levels increase post treatment the response rate to chemotherapy is significantly lower (55% versus 88% if both VEGF and PGE2 decrease post treatment, p=0.05). Thus, both VEGF and PGE2 are critical factors in determining response rate. Whether COX-2 activity is driving both factors or whether VEGF is independently regulated is yet to be determined. Clinical Response versus Dendritic cell (DCs) / T-cell data: Data revealed highly important trends that warrant future investigation. Patients with increased B7H4 (an immunosuppressive molecule expressed on tolerizing DCs) were non-responders while patients with decreased B7H4 were responders. In contrast, responders had increased levels of CD80 and CD86 (co-stimulatory molecules expressed on activating DCs). VEGF/PGE2 Change versus Dendritic/T-cell data: When VEGF increased post treatment, B7H4 and FoxP3 (T regulatory cells) increased, while CD80, CD86, and CD8 decreased. The association between VEGF and immune cells post chemotherapy treatment is the first indication that VEGF may regulate immune cell function possibly independent of COX-2 activity. These data suggest that anti-VEGF therapy (which may include COX-2 inhibitor) may not only augment responses to chemotherapy but may also augment immune responses post chemotherapy.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5110.

N0377: Results of NCCTG phase II trial of the mTOR inhibitor RAD-001 in metastatic melanoma

8530

Background: RAD-001 (Everolimus) is an oral inhibitor of mammalian target of rapamycin (mTOR). Interim analysis results from a phase II study of RAD-001 in patients with metastatic melanoma (MM) were presented at ASCO 2005. This study was re-opened using a higher dose based on an improvement in the 16 week progression free survival (PFS) rate and good tolerability. Methods: A two- stage, phase II multi-institutional trial was conducted in patients with MM to assess that 16 weeks PFS rate was at least 50%. Inclusion criteria: measurable disease, ECOG performance score of 0–2. Exclusion criteria: presence of intracranial metastases, concurrent use of inducers of cytochrome 3A4 and abnormal organ function. The dose of RAD-001 in the second cohort was increased to 10 mg daily (increased from 30 mg weekly) based on evidence of safety of the higher dose. Results: Twenty-nine patients were enrolled; baseline information is available on 27. Median age was 63 yrs; 15 (56%) had >2 sites of metastatic disease. Most (48%) had stage M1c disease. PS was 0, 1 and 2 in 58%, 38% and 4%. All but 4 (15%) had received prior therapy. Grade 3 adverse events included stomatitis and fatigue (2 each), leukopenia, neutropenia, diarrhea, anorexia, dehydration, dyspnea, hyperglycemia, and hypersensitivity (1 each). Planned interim analysis was done after 20 patients were enrolled. 14 (70%) had progressed 16 weeks, failing to meet the decision rule needed (PFS >30%) to restart accrual. The median PFS for all 29 patients was 56 days. The median overall survival (OS) has not been reached. For the entire cohort of 53 pts treated on this study (at both dose levels), the median PFS, median OS were 59 and 286 days respectively. Conclusion: Interim analysis after enrollment of 20 patients at a higher dose of RAD-001 demonstrated significantly more toxicity and no added clinical efficacy. The 16 week PFS rate target was not reached, and accrual was suspended.

No significant financial relationships to disclose.

Phase II trial of the mTOR inhibitor everolimus (RAD-001) in metastatic melanoma

8043

Background: Mammalian target of rapamycin (mTOR) is a serine-threonine kinase that regulates the production vascular endothelial growth factor (VEGF) and cell growth and proliferation. Inhibitors of mTOR have anti-mitotic and anti-angiogenic effects in various cancers (including melanoma). Everolimus (RAD-001), an orally administered inhibitor of mTOR, is well tolerated at a dose of 30 mg/week. We conducted a phase II study to evaluate the role of RAD-001 in treating patients with metastatic melanoma (MM). Methods: A 2 stage, phase II multi-institutional trial was conducted in patients with MM to assess progression free survival (PFS) rate at 16 weeks was at least 50% against the alternative it was at most 30%. Data about expected baseline PFS were derived from historical controls. Each cycle was 8 weeks in duration. Inclusion criteria: measurable disease, ECOG performance score (PS) of 0–2. Exclusion criteria: presence of intracranial metastases, concurrent use of inducers of cytochrome 3A4 and abnormal hepatic, renal or bone marrow function. Correlative studies included changes pharmacodynamic endpoints to evaluate effect of therapy on signaling pathways. Results: 24 patients with MM were enrolled. Median age was 56 years (33–79), 21 (88%) had at 2 or more sites of metastatic disease. Most (75%) had stage M1c, with 13% each having 1a and 1b disease. PS was 0, 1 and 2 in 58, 38% and 4%, resp. All but 9 had received previous therapy for MM. Planned interim analysis was done after 20 patients were enrolled. Of these, 7 (i.e., 35%) were PF at 16 weeks, which exceeded the decision rule for restarting accrual. No patient had an objective response; all 7 had stable disease. There were no grade 3 toxicities. Grade 2 toxic events (at least possibly related to therapy) were: fatigue (17%), diarrhea (8%) and anemia (8%). Patients had a clinically relevant benefit, with the median PFS for all 24 patients of 3 months. Median overall survival was not reached. Three patients continue on therapy. RAD-001 treatment resulted in changes in serum VEGF levels. Conclusion: Interim analysis after enrollment of 20 patients suggests that RAD-001 is well tolerated and has sufficient anti-tumor activity in MM to warrant the opening of enrollment to the second stage of this trial. Further accrual is planned.

No significant financial relationships to disclose.

Fractional oxidation of chylomicron-derived oleate is greater than that of palmitate in healthy adults fed frequent small meals

Differences in oxidation of individual dietary fatty acids could contribute to the effect of dietary fat composition on risk factors for non-insulin-dependent diabetes mellitus and cardiovascular disease. Using a novel stable isotope technique, we compared fractional oxidation of chylomicron-derived oleate and palmitate in 10 healthy adults in a crossover study. 1-(13)C-labeled oleate or palmitate was emulsified into a eucaloric formula diet administered each 20 min for 7 h to produce a plateau in excretion of (13)C label in breath CO(2). Unlabeled oleate and palmitate each provided 16% of dietary energy, and other fatty acids provided 8% of energy. Total dietary fat was 40% of energy, carbohydrate was 46%, and protein was 14%. Diet without tracer was fed for 2 h before beginning tracer administration to establish a baseline fed state. Relative oxidation of oleate versus palmitate was defined as fractional oxidation of oleate divided by fractional oxidation of palmitate. Relative oxidation averaged 1.21 (99.5% confidence interval = 1.03;-1.39), indicating that fractional oxidation of oleate was significantly greater than that of palmitate.

Glucose-6-phosphate dehydrogenase from Saccharomyces cerevisiae is a glycoprotein

A commercial preparation of glucose-6-phosphate dehydrogenase (G6PD) purified from Saccharomyces cerevisiae was subjected to PAGE analysis under both nondenaturing and denaturing conditions. The enzyme, identified by both activity staining and anti-yeast G6PD antibody immunoblotting, was shown to contain carbohydrate using the highly specific periodate-digoxigenin antidigoxigenin method which is diagnostic for glycoproteins.

Advances in molecular biology: implications for the future of clinical nutrition practice

Advances in molecular biology during the past decade have substantially contributed to our understanding of how genes influence physiologic processes and, ultimately, our health. Genes associated with many nutrition-related chronic diseases are being identified and characterized. Nutrients may directly or indirectly influence the transcription and/or translation of specific gene products. Identifying genetic markers for specific diseases and exploring gene therapy will provide new opportunities and challenges for clinical nutrition practice in the 21st century. Nutrition practitioners must be cognizant of developments in molecular biology to meet the challenges of providing nutrition care in the future.

Depletion and repletion of biotinyl enzymes in liver of biotin-deficient rats: evidence of a biotin storage system

The quantities of biotinyl proteins in liver of young rats were compared with age-matched controls at intervals during depletion and repletion of biotin. Growth rate and the concentrations of biotinyl proteins previously proposed as mitochondrial storage forms of acetyl CoA carboxylase rapidly decreased in response to biotin deprivation, whereas neither the concentration nor activity of cytosolic acetyl CoA carboxylase was affected. Concentrations of carboxylases active within mitochondria (pyruvate carboxylase, propionyl CoA carboxylase and 3-methyl crotonyl CoA carboxylase) decreased only after d 28. When biotin was injected into biotin-deficient rats, concentrations of the carboxylases active within mitochondria were restored to control levels within 3 h, whereas the concentrations of putative mitochondrial storage forms of acetyl CoA carboxylase reached normal levels only after 9 h, indicating that the injected biotin was preferentially used for the synthesis of the carboxylases active within mitochondria rather than acetyl CoA carboxylase. Mitochondrial acetyl CoA carboxylase may serve as a reservoir to maintain a normal concentration of cytosolic acetyl CoA carboxylase in liver of rats deprived of biotin and provide biotin, indirectly, to maintain essentially normal concentrations of the biotinyl enzymes active within mitochondria for several weeks after rats were fed a biotin-deficient diet.

Mitochondrial acetyl-CoA carboxylase. Time course of mobilization/activation in liver of refed rats

Fasted (48 h) rats were killed at 0, 2, 4, 6, 8, 12, 16, 20 and 24 h after they were refed on a high-carbohydrate diet. An increase in the maximal activity and quantity of cystolic acetyl-CoA carboxylase was found in liver of refed rats after a lag time of about 8 h. The increased quantity of cytosolic enzyme was attributable primarily to mobilization of mitochondrial storage forms and not to substantial increase in the rate of synthesis of acetyl-CoA carboxylase.

Mitochondrial storage forms of acetyl CoA carboxylase: mobilization/activation accounts for increased activity of the enzyme in liver of genetically obese Zucker rats

In earlier reports, we have described a previously unrecognized mechanism which regulates the activity of acetyl CoA carboxylase in rat liver by the control of its distribution between relatively inactive mitochondrial and active cytosolic forms. In this study, the activity, total quantity and the subcellular distribution of acetyl CoA carboxylase were determined in liver of fed and fasted (48 h) homozygous obese (fa/fa) zucker rats and homozygous lean (Fa/Fa) littermates. The results indicate that neither diet nor genetic obesity affected the total quantity of acetyl CoA carboxylase per unit weight of liver. Instead, increased activity of this enzyme in the liver of the Zucker rat was primarily due to a shift in the subcellular distribution away from relatively inactive mitochondrial forms toward active cytosolic forms. Thus, the Zucker rat appears to be yet another example illustrating the physiological importance of regulating the activity of acetyl CoA carboxylase by controlling its subcellular distribution.

Bovine milk-fat-globule membrane contains an enzymically inactive form of acetyl-CoA carboxylase

Enzymically inactive acetyl-CoA carboxylase [acetyl-CoA:carbon-dioxide ligase (ADP-forming), EC 6.4.1.2] was found as a component of bovine milk-fat-globule membrane (MFGM). Acetyl-CoA carboxylase was present in MFGM at a higher concentration than in cytosolic or mitochondrial fractions of bovine mammary tissue, which makes it unlikely that its presence was due to simple contamination by these subcellular constituents.

Enzymatically inactive forms of acetyl-CoA carboxylase in rat liver mitochondria

Biotinyl proteins were labelled by incubation of SDS-denatured preparations of subcellular fractions of rat liver with [14C]methylavidin before polyacrylamide-gel electrophoresis. Fluorographic analysis showed that mitochondria contained two forms of acetyl-CoA carboxylase [acetyl-CoA:carbon dioxide ligase (ADP-forming) EC 6.4.1.2], both of which were precipitated by antibody to the enzyme. When both forms were considered, almost three-quarters of the total liver acetyl-CoA carboxylase was found in the mitochondrial fraction of liver from fed rats while only 3.5% was associated with the microsomal fraction. The remainder was present in cytosol, either as the intact active enzyme or as a degradation product. The actual specific activity of the cytosolic enzyme was approx. 2 units/mg of acetyl-CoA carboxylase protein while that of the mitochondrial enzyme was about 20-fold lower, indicating that mitochondrial acetyl-CoA carboxylase was relatively inactive. Fractionation of mitochondria with digitonin showed that acetyl-CoA carboxylase was associated with the outer mitochondrial membrane. The available evidence suggests that mitochondrial acetyl-CoA carboxylase represents a reservoir of enzyme which can be released and activated under lipogenic conditions.

Acute alloxan diabetes alters the activity but not the total quantity of acetyl CoA carboxylase in rat liver

Alloxan diabetes has repeatedly been shown to reduce lipogenesis in rat liver concomitant with decreased activity of acetyl CoA carboxylase. This and other observations led to the deduction that insulin is required for the synthesis of acetyl CoA carboxylase even though the actual amount of enzyme was not measured. We have developed methods to determine the quantity of acetyl CoA carboxylase in crude tissue extracts with which we have reexamined the role of insulin in regulating the amount of the enzyme in liver of acute (3-d) alloxan diabetic rats. The results show that although there was a decrease in the quantity of the active cytoplasmic form of acetyl CoA carboxylase in the liver of alloxan diabetic rats, there was a corresponding increase in the quantity of relatively inactive forms of the enzyme associated with mitochondria. Thus, the total amount of enzyme was minimally affected by the diabetic state. Instead, the results indicate that decreased acetyl CoA carboxylase activity in liver of the diabetic rats was attributable to a shift in the subcellular distribution of the enzyme from the active cytoplasmic to inactive mitochondrial forms. We have shown previously that subcellular distribution of the enzyme is dietary dependent. Results of this study implicate insulin in the mobilization and activation of mitochondrial acetyl CoA carboxylase.

Determination of the quantity of acetyl CoA carboxylase by [14C]methyl avidin binding

Conditions are described under which monomeric [14C]methyl avidin binds to SDS-denatured biotin enzymes and remains bound through polyacrylamide gel electrophoresis. The location of radioactive proteins on the dried gel was determined by fluorography and their identity was established by subunit molecular weight. The relative quantity of bound radioactive avidin, stoichiometrically equivalent to the molar quantity of biotin protein, can be determined by scanning the fluorograph with a soft laser densitometer. To determine the absolute quantity of biotin protein, the radioactive areas of the dried gel were cut out, resolubilized, and assayed for radioactivity. Since the specific radioactivity of the [14C]methyl avidin was known, the quantity of avidin bound and therefore the quantity of biotin enzyme could be calculated. The method is illustrated by the analysis of purified acetyl CoA carboxylase and is applied to the analysis of biotin enzymes in isolated rat liver mitochondria.

Effect of dietary 7-ketocholesterol, pure, or oxidized cholesterol on hepatic 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity, energy balance, egg cholesterol concentration, and 14C-acetate incorporation into yolk lipids of laying hens

Experiments were conducted to study the effect of 7-ketocholesterol (7-k) in the presence or absence of pure cholesterol (PCH) or oxidized cholesterol (OCH) in diets of laying hens on reproductive performance and several parameters of cholesterol metabolism. In the first experiment, cholesterol synthesis and transport was examined by the in ovo incorporation of 14C-acetate into yolk triglycerides and cholesterol. Energy balances were also conducted. In the second experiment, hepatic 3 hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity was measured in vitro to evaluate potential cholesterol synthesis. In both experiments, reproductive performance and egg yolk cholesterol concentration were measured. Dietary PCH or OCH (.5%) significantly reduced relative acetate incorporation into yolk cholesterol, while 7-k (.025%) had no effect on carbon flow from acetate into egg cholesterol. While 7-k alone did not alter total yolk cholesterol concentration, it moderated the effect of PCH or OCH on increasing yolk cholesterol concentration. No consistent effects of dietary sterols on reproductive performance or energy balance were observed. Hepatic HMG CoA reductase activity was dramatically suppressed by feeding PCH or OCH and moderately suppressed by 7-k. In combination with PCH or OCH, 7-k did not further depress enzyme activity. The observations that 7-k alone depressed hepatic HMG-CoA reductase activity, without changing relative acetate incorporation into yolk cholesterol while limiting cholesterol deposition in egg yolk from PCH or OCH, is interpreted to mean that 7-k may stimulate sterol transport and excretion while limiting cholesterol synthesis.

Dietary dependent distribution of acetyl CoA carboxylase between cytoplasm and mitochondria of rat liver

Biotinyl proteins in cytoplasm and mitochondria of rat liver were examined by fluorography and the quantity of acetyl CoA carboxylase was determined after sodium dodecyl sulfate-denatured proteins were incubated with [14C] methyl avidin and separated by polyacrylamide gel electrophoresis. Results show that one-half of the total acetyl CoA carboxylase in liver of fed rats was associated with mitochondria in a relatively inactive form. Fasting shifted the distribution of the enzyme toward the mitochondrial fraction and refeeding previously fasted rats shifted the distribution towards cytoplasm. Thus, acetyl CoA carboxylase can be added to the list of ambiquitous enzymes whose subcellular distribution varies with physiological conditions.

Effect of cholesterol oxidation products on cholesterol metabolism in the laying hen

Two experiments were conducted to determine the effect of purified cholesterol and oxidized cholesterol in the diet of the laying hen on egg production characteristics, in vitro - in ovo utilization of acetate for cholesterol biosynthesis, and the activity of hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate-limiting enzyme in biosynthesis of cholesterol. Previous work has demonstrated inhibition of cholesterol synthesis by cholesterol oxides in tissue culture cells but not in hepatic tissues of animals through dietary administration. Feeding .5% of either purified or oxidized cholesterol had no effect on egg production, egg weight, body weight, or diet consumption. In both experiments egg yolk cholesterol was significantly increased by both cholesterol sources, but eggs from hens fed oxidized cholesterol had lower cholesterol contents than those from hens fed purified cholesterol. Relative utilization of acetate for cholesterol biosynthesis was significantly reduced by feeding both cholesterol sources. Hepatic enzyme activity measured by production of mevalonic acid was significantly inhibited by feeding purified cholesterol. A further significant reduction in enzyme activity was observed when oxidized cholesterol was fed, indicating that dietary cholesterol oxides are much more potent than purified cholesterol in limiting the activity of the enzyme.

Molecular weights of subunits of acetyl CoA carboxylase in rat liver cytoplasm

Monomeric [14C] methyl avidin was shown to bind to sodium dodecyl sulfate-denatured biotinyl proteins and remain bound through polyacrylamide gel electrophoresis which allowed their detection by fluorography. This method was used to show that purified rat liver acetyl CoA carboxylase contained two high molecular weight forms of the enzyme (MR = 241,000 and 252,000) while rapidly prepared, crude rat liver cytoplasm contained two larger molecular weight (MR = 257,000 and 270,000) forms. Thus, the enzyme had undergone substantial proteolysis during purification. The crude enzyme preparation also contained a smaller biotinyl protein (MR = 141,000) which is likely a proteolytic product of the larger forms of acetyl CoA carboxylase.

Regulation of purified rat liver acetyl CoA carboxylase by phosphorylation

Acetyl CoA carboxylase was purified from liver of fasted-refed rats to near homogeneity, based on electrophoretic analysis and biotin content. These preparations contained an endogenous protein kinase that catalyzed the transfer of radioactive phosphate from [gamma-32P]ATP to acetyl CoA carboxylase, accompanied by a decrease in acetyl CoA carboxylase activity. Phosphate incorporated into acetyl CoA carboxylase was removed when the preparation was incubated with partially purified phosphorylase phosphatase catalytic subunit with regain of enzymatic activity. This endogenous protein kinase was shown not to be affected by either cyclic-AMP-dependent protein kinase inhibitor, EGTA, or trifluoperazine. The addition of either cyclic-AMP or purified cyclic-AMP-dependent protein kinase catalytic subunit to the purified acetyl CoA carboxylase preparation increased protein phosphorylation but had no further effect on acetyl CoA carboxylase activity. Purified acetyl CoA carboxylase was shown to act as an ATPase during the phosphorylation reaction.

Inhibition of rat liver acetyl CoA carboxylase by chloride

The activity of acetyl CoA carboxylase in both crude and purified rat liver preparations was reduced in the presence of sodium or potassium chloride and increased in the presence of potassium acetate. The chloride inhibition was not competitive with bicarbonate. The use of Trischloride buffer did not alter the apparent pH optimum of the enzyme when compared with Tris-acetate buffer.

Heat activation of rat liver acetyl-CoA carboxylase in vitro

Acetyl-CoA carboxylase in rat liver homogenates was activated in vitro in a time- and temperature-dependent manner. The activity of acetyl-CoA carboxylase in rat liver preparations was determined in a 1-min assay to preclude the possibility of citrate activation of the enzyme during the assay period. Activation of the enzyme occurred more rapidly in liver preparations continuously maintained at ambient or greater temperatures than in homogenates of liver which had been chilled. High speed supernatant (105,000 X g, 60 min) did not heat-activate, and reconstitution of the heat-activatable 27,000 X g, 20-min, fraction by recombining the high speed pellet with the high speed supernatant only partially restored the heat activatability. Elution of the 105,000 X g supernatant from Sephadex G-25 resulted in an enzyme preparation which was heat-activatable. Addition of boiled 105,000 X g supernatant to the Sephadex G-25-treated enzyme again prevented heat activation. Dilution of the enzyme 5-fold did not prevent heat activation.