Reference Samples to Compare Next-Generation Sequencing Test Performance for Oncology Therapeutics and Diagnostics

OBJECTIVES

Diversity of laboratory-developed tests (LDTs) using next-generation sequencing (NGS) raises concerns about their accuracy for selection of targeted therapies. A working group developed a pilot study of traceable reference samples to measure NGS LDT performance among a cohort of clinical laboratories.

METHODS

Human cell lines were engineered via CRISPR/Cas9 and prepared as formalin-fixed, paraffin-embedded cell pellets ("wet" samples) to assess the entire NGS test cycle. In silico mutagenized NGS sequence files ("dry" samples) were used to assess the bioinformatics component of the NGS test cycle. Single and multinucleotide variants (n = 36) of KRAS and NRAS were tested at 5% or 15% variant allele fraction to determine eligibility for therapy with the EGFR inhibitor panitumumab in the setting of metastatic colorectal cancer.

RESULTS

Twenty-one (21/21) laboratories tested wet samples; 19 of 21 analyzed dry samples. Of the laboratories that tested both the wet and dry samples, 7 (37%) of 19 laboratories correctly reported all variants, 3 (16%) of 19 had fewer than five errors, and 9 (47%) of 19 had five or more errors. Most errors were false negatives.

CONCLUSIONS

Genetically engineered cell lines and mutagenized sequence files are complementary reference samples for evaluating NGS test performance among clinical laboratories using LDTs. Variable accuracy in detection of genetic variants among some LDTs may identify different patient populations for targeted therapy.

Abstract 3008: Preclinical characterization of AMG 900, a pan-aurora kinase inhibitor, alone and in combination with taxanes in ovarian cancer

BACKGROUND: Aurora kinases (AK) A and B play essential roles in multiple stages of mitosis and are frequently overexpressed in a subset of human cancers, including ovarian cancer (OC). AMG 900, a potent and highly selective small molecule inhibitor of AKs, showed promising single-agent activity in heavily pretreated patients with advanced OC in a Phase 1b clinical trial. In this study, we report the preclinical effects of AMG 900 in a panel of well-characterized human cancer cell lines representing clinically-relevant OC subtypes. METHODS: The anti-proliferative effects of AMG 900 were evaluated using a 5-day cell count assay. Cell lines were classified as sensitive to AMG 900 when lethality was > 15% at 10 nM. Molecular markers were profiled including TP53 mutation status, AURKA, CCNE1, MYC copy number, and p53, p21 and cyclin E1 protein by reverse phase protein array. Flow cytometry and imaging methods were used to evaluate the mechanism of action of AMG 900 alone and in combination with chemotherapy. The combination of AMG 900 plus docetaxel was evaluated in an IGROV-1 ovarian endometrioid carcinoma xenograft model. RESULTS: One third of the cell lines (11 of 35) were classified as sensitive to AMG 900 and showed enrichment for TP53 mutations and serous OC subtype. However, 10 of 24 resistant cell lines harbored TP53 mutations, indicating that TP53 mutational status alone was not sufficient for predicting AMG 900 sensitivity. Inhibition of AK activity by AMG 900 in OC cells resulted in aborted cell division leading to polyploidy and cell death (suggestive of aurora-B dominant phenotype). Re-plating of remnant cells after AMG 900 treatment showed an attenuation of cell regrowth, where TP53mut IGROV-1 cells showed minimal regrowth compared to TP53wt OVCAR-5 cells. AMG 900 inhibited proliferation at low nanomolar concentrations in the majority of OC cell lines and enhanced the effects of paclitaxel, carboplatin, and doxorubicin in IGROV-1 cells. In tumor-bearing mice, administration of AMG 900 at 7.5 mg/kg (PO) for two days per week or docetaxel at 10 mg/kg (IP) weekly for four cycles significantly inhibited the growth of IGROV-1 tumor xenografts (P < .0001 vs. vehicle alone). Notably, co-administration of AMG 900 with docetaxel enhanced efficacy and induced a delay in tumor regrowth compared to docetaxel alone. Single-agent-treated mice showed minimal body weight loss (BWL), whereas combination-treated mice showed moderate BWL (average < 10%) that was largely reversible (2 of 12 animals removed due to toxicity). CONCLUSIONS: AMG 900 alone or in combination with chemotherapy such as paclitaxel may be a promising clinical strategy to treat patients with ovarian cancer.

Citation Format: Ondrej Kalous, Dylan Conklin, Kanthinh Manivong, William Wayne, Kelly Hanestad, Jude Canon, Robert Loberg, Gregory Friberg, Erick Gamelin, Florian D. Vogl, Gloria Juan, Angela Coxon, Dennis Slamon, Richard Finn, Marc Payton. Preclinical characterization of AMG 900, a pan-aurora kinase inhibitor, alone and in combination with taxanes in ovarian cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3008.

Abstract 439: Detection of aurora kinase A (AURKA) focal amplification in plasma samples of patients with recurrent ovarian cancer

Purpose: Aurora kinases are associated with acquired resistance to therapy in human cancers. We hypothesized that AURKA amplification is a late event in ovarian cancer (OC) progression and that frequency of amplification might be underestimated if assessed in tumor samples collected at the time of initial diagnosis. To test this hypothesis, we determined AURKA amplification levels in patients with recurrent OC and

compared those to AURKA amplification levels in the same patients at the time of diagnosis.

Methods: Samples were collected from 33 patients with taxane- and platinum-resistant OC enrolled in a first-in-human (FIH) study that evaluated monotherapy with AMG 900, an orally administered pan-aurora kinase inhibitor (NCT00858377). We performed a targeted analysis of

the AURKA locus and surrounding regions using next-generation paired-end sequencing (Illumina HiSeq2500 and 100 bp paired-end reads). By using extremely high sequence coverage (average coverage of > 2,000-fold), we were able to detect and quantify circulating tumor DNA (ctDNA) in plasma and to identify chromosomal alterations characteristic of tumor DNA. Sequencing was performed at Personal Genome Diagnostics (PGDx, Baltimore, MD). In addition, we performed AURKA (20q13) / 20q11 FISH in archival FFPE sections from the same patients. The AURKA (20q13) / 20q11 dual color FISH probe kit was purchased from Kreatech (now Leica Biosystems, Buffalo Grove, IL). Amplification states were defined as follows: amplified: AURKA (20q13) / 20q11 signal > 2.0; borderline: AURKA (20q13) / 20q11 signal < 2.0 and > 1.5; non-amplified: AURKA (20q13) / 20q11 signal < 1.5. FISH analyses were performed at Mosaic Laboratories (Lake Forest, CA). Survival analysis was performed using the Kaplan-Meier method.

Results: Plasma samples were available from all patients. Analysis of rearrangements surrounding the AURKA locus in plasma samples identified 11 of the 33 patients as AURKA amplified. Archival FFPE

sections were available from 27 of the 33 patients, and 21 of these 27 patients were evaluable by FISH for AURKA amplification. FISH only identified 1 patient as AURKA amplified and 1 additional patient as borderline amplified. Patients with AURKA amplification in plasma had received a median (min, max) of 6 (2,18) prior lines of chemotherapy, while patients without AURKA amplification had received a median (min, max) of 3 (1, 14) lines of prior chemotherapy. AURKA amplification as determined in plasma ctDNA at the time of AMG 900 study entry was an indicator of shorter PFS (median 9.4 vs 19.9 weeks; P = 0.04) and OS (median 9.4 vs 27.6 weeks; P = 0.013).

Conclusions: Our results suggest that AURKA amplification is a late event in ovarian cancer progression,and that monitoring AURKA focal amplification in plasma ctDNA allows the non-invasive assessment of acquired resistance to cancer therapy.

Citation Format: Gloria Juan, Katherine Paweletz, Abraham Anderson, Erick Gamelin, Gregory Friberg, Robert Loberg, Florian Vogl. Detection of aurora kinase A (AURKA) focal amplification in plasma samples of patients with recurrent ovarian cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 439.

A first-in-human study of AMG 208, an oral MET inhibitor, in adult patients with advanced solid tumors

BACKGROUND

This first-in-human study evaluated AMG 208, a small-molecule MET inhibitor, in patients with advanced solid tumors.

METHODS

Three to nine patients were enrolled into one of seven AMG 208 dose cohorts (25, 50, 100, 150, 200, 300, and 400 mg). Patients received AMG 208 orally on days 1 and days 4-28 once daily. The primary objectives were to evaluate the safety, tolerability, pharmacokinetics, and maximum tolerated dose (MTD) of AMG 208.

RESULTS

Fifty-four patients were enrolled. Six dose-limiting toxicities were observed: grade 3 increased aspartate aminotransferase (200 mg), grade 3 thrombocytopenia (200 mg), grade 4 acute myocardial infarction (300 mg), grade 3 prolonged QT (300 mg), and two cases of grade 3 hypertension (400 mg). The MTD was not reached. The most frequent grade ≥3 treatment-related adverse event was anemia (n = 3) followed by hypertension, prolonged QT, and thrombocytopenia (two patients each). AMG 208 exposure increased linearly with dose; mean plasma half-life estimates were 21.4-68.7 hours. One complete response (prostate cancer) and three partial responses (two in prostate cancer, one in kidney cancer) were observed.

CONCLUSIONS

In this study, AMG 208 had manageable toxicities and showed evidence of antitumor activity, particularly in prostate cancer.

A phase 3 randomized, double-blind, placebo-controlled trial of ganitumab or placebo in combination with gemcitabine as first-line therapy for metastatic adenocarcinoma of the pancreas: the GAMMA trial

BACKGROUND

This double-blind, phase 3 study assessed the efficacy and safety of ganitumab combined with gemcitabine as first-line treatment of metastatic pancreatic cancer.

PATIENTS AND METHODS

Patients with previously untreated metastatic pancreatic adenocarcinoma were randomly assigned 2 : 2 : 1 to receive intravenous gemcitabine 1000 mg/m(2) (days 1, 8, and 15 of each 28-day cycle) plus placebo, ganitumab 12 mg/kg, or ganitumab 20 mg/kg (days 1 and 15 of each cycle). The primary end point was overall survival (OS). Secondary end points included progression-free survival (PFS), safety, and efficacy by levels of circulating biomarkers.

RESULTS

Overall, 322 patients were randomly assigned to placebo, 318 to ganitumab 12 mg/kg, and 160 to ganitumab 20 mg/kg. The study was stopped based on results from a preplanned futility analysis; the final results are reported. Median OS was 7.2 months [95% confidence interval (CI), 6.3-8.2] in the placebo arm, 7.0 months (95% CI, 6.2-8.5) in the ganitumab 12-mg/kg arm [hazard ratio (HR), 1.00; 95% CI, 0.82-1.21; P = 0.494], and 7.1 months (95% CI, 6.4-8.5) in the ganitumab 20-mg/kg arm (HR, 0.97; 95% CI, 0.76-1.23; P = 0.397). Median PFS was 3.7, 3.6 (HR, 1.00; 95% CI, 0.84-1.20; P = 0.520), and 3.7 months (HR, 0.97; 95% CI, 0.77-1.22; P = 0.403), respectively. No unexpected toxicity was observed with ganitumab plus gemcitabine. The circulating biomarkers assessed [insulin-like growth factor-1 (IGF-1), IGF-binding protein-2, and -3] were not associated with a treatment effect on OS or PFS by ganitumab.

CONCLUSION

Ganitumab combined with gemcitabine had manageable toxicity but did not improve OS, compared with gemcitabine alone in unselected patients with metastatic pancreatic cancer.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT01231347.

AMG 900, a potent inhibitor of aurora kinases causes pharmacodynamic changes in p-Histone H3 immunoreactivity in human tumor xenografts and proliferating mouse tissues

BACKGROUND

The Aurora family of serine-threonine kinases are essential regulators of cell division in mammalian cells. Aurora-A and -B expression and kinase activity is elevated in a variety of human cancers and is associated with high proliferation rates and poor prognosis. AMG 900 is a highly potent and selective pan-aurora kinase inhibitor that has entered clinical evaluation in adult patients with advanced cancers. In mice, oral administration of AMG 900 blocks the phosphorylation of histone H3 on serine-10 (p-Histone H3), a proximal substrate of aurora-B and inhibits the growth of multiple human tumor xenografts, including multidrug-resistant models.

METHODS

In order to establish a preclinical pharmacokinetic-pharmacodynamic (PK-PD) relationship for AMG 900 that could be translated to the clinic, we used flow cytometry and laser scanning cytometry detection platforms to assess the effects on p-Histone H3 inhibition in terms of sensitivity, precision, and specificity, in human tumor xenografts in conjunction with mouse skin and bone marrow tissues. Mice with established COLO 205 tumors were administered AMG 900 at 3.75, 7.5, and 15 mg/kg and assessed after 3 hours.

RESULTS

Significant suppression of p-Histone H3 in mouse skin was only observed at 15 mg/kg (p <0.0001), whereas in mouse bone marrow and in tumor a dose-dependent inhibition was achieved at all three doses (p ≤ 0.00015). These studies demonstrate that AMG 900 inhibits p-Histone H3 in tumors and surrogate tissues (although tissues such as skin may be less sensitive for assessing PD effects). To further extend our work, we evaluated the feasibility of measuring p-Histone H3 using fine-needle aspirate (FNA) tumor xenograft biopsies. Treatment with AMG 900 significantly inhibited p-Histone H3 (>99% inhibition, p <0.0001) in COLO 205 tumors. Lastly, we illustrate this LSC-based approach can detect p-Histone H3 positive cells using mock FNAs from primary human breast tumor tissues.

CONCLUSION

Phosphorylation of histone H3 is a useful biomarker to determine the pharmacodynamics (PD) activity of AMG 900. FNA biopsies may be a viable approach for assessing AMG 900 PD effects in the clinic.

AMG 900, a small-molecule inhibitor of aurora kinases, potentiates the activity of microtubule-targeting agents in human metastatic breast cancer models

Breast cancer is the most prevalent malignancy affecting women and ranks second in cancer-related deaths, in which death occurs primarily from metastatic disease. Triple-negative breast cancer (TNBC) is a more aggressive and metastatic subtype of breast cancer that is initially responsive to treatment of microtubule-targeting agents (MTA) such as taxanes. Recently, we reported the characterization of AMG 900, an orally bioavailable, potent, and highly selective pan-Aurora kinase inhibitor that is active in multidrug-resistant cell lines. In this report, we investigate the activity of AMG 900 alone and in combination with two distinct classes of MTAs (taxanes and epothilones) in multidrug-resistant TNBC cell lines and xenografts. In TNBC cells, AMG 900 inhibited phosphorylation of histone H3 on Ser(10), a proximal substrate of Aurora-B, and induced polyploidy and apoptosis. Furthermore, AMG 900 potentiated the antiproliferative effects of paclitaxel and ixabepilone at low nanomolar concentrations. In mice, AMG 900 significantly inhibited the growth of MDA-MB-231 (F(11); parental), MDA-MB-231 (F(11)) PTX-r (paclitaxel-resistant variant), and DU4475 xenografts. The combination of AMG 900 with docetaxel enhanced tumor inhibition in MDA-MB-231 (F(11)) xenografts compared with either monotherapy. Notably, combining AMG 900 with ixabepilone resulted in regressions of MDA-MB-231 (F(11)) PTX-r xenografts, in which more than 50% of the tumors failed to regrow 75 days after the cessation of drug treatment. These findings suggest that AMG 900, alone and in combination with MTAs, may be an effective intervention strategy for the treatment of metastatic breast cancer and provide potential therapeutic options for patients with multidrug-resistant tumors.

A randomized, placebo-controlled phase 2 study of ganitumab or conatumumab in combination with FOLFIRI for second-line treatment of mutant KRAS metastatic colorectal cancer

BACKGROUND

Targeted agents presently available for mutant KRAS metastatic colorectal cancer (mCRC) are bevacizumab and aflibercept. We evaluated the efficacy and safety of conatumumab (an agonistic monoclonal antibody against human death receptor 5) and ganitumab (a monoclonal antibody against the type 1 insulin-like growth factor receptor) combined with standard FOLFIRI chemotherapy as a second-line treatment in patients with mutant KRAS mCRC.

PATIENTS AND METHODS

Patients with mutant KRAS metastatic adenocarcinoma of the colon or rectum refractory to fluoropyrimidine- and oxaliplatin-based chemotherapy were randomized 1 : 1 : 1 to receive intravenous FOLFIRI plus conatumumab 10 mg/kg (Arm A), ganitumab 12 mg/kg (Arm B), or placebo (Arm C) Q2W. The primary end point was progression-free survival (PFS).

RESULTS

In total, 155 patients were randomized. Median PFS in Arms A, B, and C was 6.5 months (HR, 0.69; P = 0.147), 4.5 months (HR, 1.01; P = 0.998), and 4.6 months, respectively; median overall survival was 12.3 months (HR, 0.89; P = 0.650), 12.4 months (HR, 1.27; P = 0.357), and 12.0 months; and objective response rate was 14%, 8%, and 2%. The most common grade ≥3 adverse events in Arms A/B/C included neutropenia (30%/25%/18%) and diarrhea (18%/2%/10%).

CONCLUSIONS

Conatumumab, but not ganitumab, plus FOLFIRI was associated with a trend toward improved PFS. Both combinations had acceptable toxicity.

Discovery of potent and highly selective thienopyridine Janus kinase 2 inhibitors

Developing Janus kinase 2 (Jak2) inhibitors has become a significant focus for small molecule drug discovery programs in recent years due to the identification of a Jak2 gain-of-function mutation in the majority of patients with myeloproliferative disorders (MPD). Here, we describe the discovery of a thienopyridine series of Jak2 inhibitors that culminates with compounds showing 100- to >500-fold selectivity over the related Jak family kinases in enzyme assays. Selectivity for Jak2 was also observed in TEL-Jak cellular assays, as well as in cytokine-stimulated peripheral blood mononuclear cell (PBMC) and whole blood assays. X-ray cocrystal structures of 8 and 19 bound to the Jak2 kinase domain aided structure-activity relationship efforts and, along with a previously reported small molecule X-ray cocrystal structure of the Jak1 kinase domain, provided structural rationale for the observed high levels of Jak2 selectivity.

A destructive cascade mediated by CCL2 facilitates prostate cancer growth in bone

Monocyte chemoattractant protein 1 (CCL2) is a recently identified prominent regulator of prostate cancer growth and metastasis. The purpose of this study was to investigate the mechanistic role of CCL2 in prostate cancer growth in bone. The present study found that CCL2 was up-regulated in osteoblasts (3-fold by PC-3 and 2-fold by VCaP conditioned medium) and endothelial cells (2-fold by PC-3 and VCaP conditioned medium). Parathyroid hormone-related protein (PTHrP) treatment of osteoblastic cells up-regulated CCL2 and was blocked by a PTHrP antagonist, suggesting that prostate cancer-derived PTHrP plays an important role in elevation of osteoblast-derived CCL2. CCL2 indirectly increased blood vessel formation in endothelial cells through vascular endothelial growth factor-A, which was up-regulated 2-fold with administration of CCL2 in prostate cancer cells. In vivo, anti-CCL2 treatment suppressed tumor growth in bone. The decreased tumor burden was associated with decreased bone resorption (serum TRAP5b levels were decreased by 50-60% in anti-CCL2-treated animals from VCaP or PC-3 cell osseous lesions) and microvessel density was decreased by 70% in anti-CCL2-treated animals with bone lesions from VCaP cells. These data suggest that a destructive cascade is driven by tumor cell-derived, PTHrP-mediated induction of CCL2, which facilitates tumor growth via enhanced osteoclastic and endothelial cell activity in bone marrow. Taken together, CCL2 mediates the interaction between tumor-derived factors and host-derived chemokines acting in cooperation to promote skeletal metastasis.

The role of CXCR7/RDC1 as a chemokine receptor for CXCL12/SDF-1 in prostate cancer

Several reports have recently documented that CXCR7/RDC1 functions as a chemokine receptor for SDF-1/CXCL12, which regulates a spectrum of normal and pathological processes. In this study, the role of CXCR7/RDC1 in prostate cancer (PCa) was explored. Staining of high density tissue microarrays demonstrates that the levels of CXCR7/RDC1 expression increase as the tumors become more aggressive. In vitro and in vivo studies with PCa cell lines suggest that alterations in CXCR7/RDC1 expression are associated with enhanced adhesive and invasive activities in addition to a survival advantage. In addition, it was observed that CXCR7/RDC1 levels are regulated by CXCR4. Among the potential downstream targets of CXCR7/RDC1 are CD44 and cadherin-11, which are likely to contribute to the invasiveness of PCa cells. CXCR7/RDC1 also regulates the expression of the proangiogenic factors interleukin-8 or vascular endothelial growth factor, which are likely to participate in the regulation of tumor angiogenesis. Finally, we found that signaling by CXCR7/RDC1 activates AKT pathways. Together, these data demonstrate a role for CXCR7/RDC1 in PCa metastasis and progression and suggest potential targets for therapeutic intervention.

The pivotal role of CXCL12 (SDF-1)/CXCR4 axis in bone metastasis

Tumor cells are known to adapt to and utilize existing physiological mechanisms to promote survival and metastasis. The role of the microenvironment in the establishment of a metastatic lesion has become increasingly important as several factors secreted by stromal cells regulate metastatic pattern in a variety of tumor types. Tumor cells interact with osteoblasts, osteoclasts and bone matrix to form a vicious cycle that is essential for successful metastases. Here we review the current concepts regarding the role of an important chemokine/chemokine receptor (SDF-1 or CXCL12/CXCR4) pathway in tumor development and metastasis. CXCL12 secretion by stromal cells is known to attract cancer cells via stimulation of the CXCR4 receptor that is up regulated by tumor cells. CXCL12/CXCR4 activation regulates the pattern of metastatic spread with organs expressing high levels of CXCL12 developing secondary tumors (i.e., the bone marrow compartment). CXCL12 has a wide range of effects in regards to tumor development but the primary role of CXCL12 appears to be the mobilization of hematopoietic stem cells and the establishment of the cancer stem-like cell niche where high levels of CXCL12 recruit a highly tumorigenic population of tumor cells and promotes cell survival, proliferation, angiogenesis, and metastasis.

The “Emigration, Migration, and Immigration” of Prostate Cancer

In the vast majority of cases, cancer continues to be an incurable disease when it has spread beyond the primary organ. Most cancer research and therapy design to date has focused on chemotherapy directed at killing the replicating tumor cells. Little attention has been placed on targeting the microenvironments of the primary tumor site, the circulating tumor cells, or the metastatic or secondary (target) tumor site and how cancer cells move among them. To develop these targets, a better understanding of metastasis and the mechanisms underlying the spread of tumors is required. This review describes the steps of metastasis using a paradigm of emigration to migration to immigration, with prostate cancer as a model system.

Expression and regulation of MIM (Missing In Metastasis), a novel putative metastasis suppressor gene, and MIM-B, in bladder cancer cell lines

It has been proposed that a 356 amino acid protein encoded by the MIM (Missing In Metastasis) gene on Chromosome 8q24.1, is a bladder cancer metastasis suppressor. Recently, Machesky and colleagues [Biochem. J. 371 (2003) 463] identified MIM-B, a 759 amino acid protein, of which the C-terminal 356 amino acids are almost identical to MIM. Importantly, PCR primers and Northern Blotting probes used in the studies of MIM in bladder cancer did not distinguish between sequences specific for MIM or MIM-B, thus the importance of either protein to bladder cancer remains unclear. We have used primer sequences specific for either MIM or MIM-B to explore the possible functional significance of MIM and MIM-B to bladder cancer cell behaviour. We have compared MIM and MIM-B mRNA levels in a non-tumourigenic, non-invasive, transformed uro-epithelial cell line versus 15 bladder cancer cell lines of differing in vitro invasive abilities, as well as in five cell lines clonally isolated from the BL17/2 bladder tumour cell line, whose in vitro and in vivo invasive abilities have been determined. MIM and MIM-B mRNA levels varied widely between cell lines. Down-regulation of MIM and MIM-B occurred in 6/15 (40%) lines but lines showing down-regulation differed between MIM and MIM-B. Reduced levels of MIM and MIM-B in BL17/2 were further reduced in 2/5 (40%) sublines (MIM and MIM-B). Importantly, there was no association between MIM or MIM-B expression and invasive behaviour in vivo or in vitro. Treatment of representative cell lines with 5-aza-2-deoxycytidine failed to induce MIM or MIM-B expression. Furthermore, there was no association between MIM or MIM-B mRNA levels and p53 functional status. Our data indicate that down-regulation of MIM and/or MIM-B expression can occur in bladder cancer cell lines but is not associated with increased invasive behaviour. Our data also suggest that in those cell lines with reduced levels of MIM and MIM-B mRNA, down-regulation is unlikely to be due to promoter hypermethylation or loss of p53 function.

Antisense GLUT-1 protects mesangial cells from glucose induction of GLUT-1 and fibronectin expression

A stable clone of rat mesangial cells expressing antisense GLUT-1 (i.e., MCGT1AS cells) was developed to protect them from high glucose exposure. GLUT-1 protein was reduced 50%, and the 2-deoxy-[(3)H]glucose uptake rate was reduced 33% in MCGT1AS. MCLacZ control cells and MCGT1 GLUT-1-overexpressing cells were used for comparisons. In MCLacZ, 20 mM D-glucose increased GLUT-1 transcription 90% vs. no increase in MCGT1AS. Glucose (8 mM) and 12 mM xylitol [a hexose monophosphate (HMP) shunt substrate] did not stimulate GLUT-1 transcription. An 87% replacement of the standard 8 mM D-glucose with 3-O-methylglucose reduced GLUT-1 transcription 80%. D-Glucose (20 mM) increased fibronectin mRNA and protein by 47 and 100%, respectively, in MCLacZ vs. no increases in MCGT1AS. Fibronectin synthesis was elevated 48% in MCGT1 and reduced 44% in MCGT1AS. We conclude that 1) transcription of GLUT-1 in response to D-glucose depends on glucose metabolism, although not through the HMP shunt, and 2) antisense GLUT-1 treatment of mesangial cells blocks D-glucose-induced GLUT-1 and fibronectin expression, thereby demonstrating a protective effect that could be beneficial in the setting of diabetes.