Michael J. Kelley

Targeting lactate-fueled respiration selectively kills hypoxic tumor cells in mice

Tumors contain oxygenated and hypoxic regions, so the tumor cell population is heterogeneous. Hypoxic tumor cells primarily use glucose for glycolytic energy production and release lactic acid, creating a lactate gradient that mirrors the oxygen gradient in the tumor. By contrast, oxygenated tumor cells have been thought to primarily use glucose for oxidative energy production. Although lactate is generally considered a waste product, we now show that it is a prominent substrate that fuels the oxidative metabolism of oxygenated tumor cells. There is therefore a symbiosis in which glycolytic and oxidative tumor cells mutually regulate their access to energy metabolites. We identified monocarboxylate transporter 1 (MCT1) as the prominent path for lactate uptake by a human cervix squamous carcinoma cell line that preferentially utilized lactate for oxidative metabolism. Inhibiting MCT1 with alpha-cyano-4-hydroxycinnamate (CHC) or siRNA in these cells induced a switch from lactate-fueled respiration to glycolysis. A similar switch from lactate-fueled respiration to glycolysis by oxygenated tumor cells in both a mouse model of lung carcinoma and xenotransplanted human colorectal adenocarcinoma cells was observed after administration of CHC. This retarded tumor growth, as the hypoxic/glycolytic tumor cells died from glucose starvation, and rendered the remaining cells sensitive to irradiation. As MCT1 was found to be expressed by an array of primary human tumors, we suggest that MCT1 inhibition has clinical antitumor potential.

Induction Chemotherapy Followed by Chemoradiotherapy Compared With Chemoradiotherapy Alone for Regionally Advanced Unresectable Stage III Non-Small-Cell Lung Cancer: Cancer and Leukemia Group B

PURPOSE Standard therapy for unresectable stage III non-small-cell lung cancer includes concomitant chemoradiotherapy. In Cancer and Leukemia Group B 39801, we evaluated whether induction chemotherapy before concurrent chemoradiotherapy would result in improved survival. PATIENTS AND METHODS Between July 1998 and May 2002, 366 patients were randomly assigned to arm A, which involved immediate concurrent chemoradiotherapy with carboplatin area under the concentration-time curve (AUC) of 2 and paclitaxel 50 mg/m2 given weekly during 66 Gy of chest radiotherapy, or arm B, which involved two cycles of carboplatin AUC 6 and paclitaxel 200 mg/m2 administered every 21 days followed by identical chemoradiotherapy. The accrual goal was 360 patients. RESULTS Thirty-four percent of patients were female, 66% were male, and the median age was 63 years. Grade 3 or 4 toxicities during induction chemotherapy on arm B consisted mainly of neutropenia (18% and 20%, respectively). During concurrent chemoradiotherapy, there was no difference in severity of in-field toxicities of esophagitis (grade 3 and 4 were, respectively, 30% and 2% for arm A v 28% and 8% for arm B) and dyspnea (grade 3 and 4 were, respectively, 11% and 3% for arm A v 15% and 4% for arm B). Survival differences were not statistically significant (P = .3), with a median survival on arm A of 12 months (95% CI, 10 to 16 months) versus 14 months (95% CI, 11 to 16 months) on arm B and a 2-year survival of 29% (95% CI, 22% to 35%) and 31% (95% CI, 25% to 38%). Age, weight loss before therapy, and performance status were statistically significant predictive factors. CONCLUSION The addition of induction chemotherapy to concurrent chemoradiotherapy added toxicity and provided no survival benefit over concurrent chemoradiotherapy alone. The median survival achieved in each of the treatment groups is low, and the routine use of weekly carboplatin and paclitaxel with simultaneous radiotherapy should be re-examined.

Mutation of MYH9, encoding non-muscle myosin heavy chain A, in May-Hegglin anomaly

May-Hegglin anomaly (MHA) is an autosomal dominant macrothrombocytopenia of unclear pathogenesis characterized by thrombocytopenia, giant platelets and leukocyte inclusions. Studies have indicated that platelet structure and function are normal, suggesting a defect in megakaryocyte fragmentation. The disorder has been linked to chromosome 22q12–13. Here we screen a candidate gene in this region, encoding non-muscle myosin heavy chain A (MYH9), for mutations in ten families. In each family, we identified one of three sequence variants within either the α-helical coiled coil or the tailpiece domain that co-segregated with disease status. The E1841K mutation was found in 5 families and occurs at a conserved site in the rod domain. This mutation was not found in 40 normal individuals. Four families had a nonsense mutation that resulted in truncation of most of the tailpiece. One family had a T1155I mutation present in an affected mother and daughter, but not in the mothers parents, thus representing a new mutation. Among the 30 affected individuals, 21 unaffected individuals and 13 spouses in the 10 families, there was correlation of a variant of MYH9 with the presence of MHA. The identification of MYH9 as the disease gene for MHA establishes the pathogenesis of the disorder, should provide further insight into the processes of normal platelet formation and may facilitate identification of the genetic basis of related disorders.

A pathway-based classification of human breast cancer

The hallmark of human cancer is heterogeneity, reflecting the complexity and variability of the vast array of somatic mutations acquired during oncogenesis. An ability to dissect this heterogeneity, to identify subgroups that represent common mechanisms of disease, will be critical to understanding the complexities of genetic alterations and to provide a framework to develop rational therapeutic strategies. Here, we describe a classification scheme for human breast cancer making use of patterns of pathway activity to build on previous subtype characterizations using intrinsic gene expression signatures, to provide a functional interpretation of the gene expression data that can be linked to therapeutic options. We show that the identified subgroups provide a robust mechanism for classifying independent samples, identifying tumors that share patterns of pathway activity and exhibit similar clinical and biological properties, including distinct patterns of chromosomal alterations that were not evident in the heterogeneous total population of tumors. We propose that this classification scheme provides a basis for understanding the complex mechanisms of oncogenesis that give rise to these tumors and to identify rational opportunities for combination therapies.

Human Nonsyndromic Hereditary Deafness DFNA17 Is Due to a Mutation in Nonmuscle Myosin MYH9

The authors had previously mapped a new locus-DFNA17, for nonsyndromic hereditary hearing impairment-to chromosome 22q12.2-q13. 3. DFNA17 spans a 17- to 23-cM region, and MYH9, a nonmuscle-myosin heavy-chain gene, is located within the linked region. Because of the importance of myosins in hearing, MYH9 was tested as a candidate gene for DFNA17. Expression of MYH9 in the rat cochlea was confirmed using reverse transcriptase-PCR and immunohistochemistry. MYH9 was immunolocalized in the organ of Corti, the subcentral region of the spiral ligament, and the Reissner membrane. Sequence analysis of MYH9 in a family with DFNA17 identified, at nucleotide 2114, a G-->A transposition that cosegregated with the inherited autosomal dominant hearing impairment. This missense mutation changes codon 705 from an invariant arginine (R) to histidine (H), R705H, within a highly conserved SH1 linker region. Previous studies have shown that modification of amino acid residues within the SH1 helix causes dysfunction of the ATPase activity of the motor domain in myosin II. Both the precise role of MYH9 in the cochlea and the mechanism by which the R705H mutation leads to the DFNA17 phenotype (progressive hearing impairment and cochleosaccular degeneration) remain to be elucidated.

T (brachyury) gene duplication confers major susceptibility to familial chordoma

Using high-resolution array-CGH, we identified unique duplications of a region on 6q27 in four multiplex families with at least three cases of chordoma, a cancer of presumed notochordal origin. The duplicated region contains only the T (brachyury) gene, which is important in notochord development and is expressed in most sporadic chordomas. Our findings highlight the value of screening for complex genomic rearrangements in searches for cancer-susceptibility genes.

Characterization of osteoclast precursors in human blood

Osteoclast precursors (OCPs) circulate in the mononuclear fraction of peripheral blood (PB), but their abundance and surface characteristics are unknown. Previous studies suggest that the receptor activator for NF‐κB (RANK) on cytokine‐treated OCPs in mouse bone marrow interacts with osteoprotegerin ligand (OPGL/TRANCE/RANKL/ODF) to initiate osteoclast differentiation. Hence, we used a fluorescent form of human OPGL (Hu‐OPGL‐F) to identify possible RANK‐expressing OCPs in untreated peripheral blood mononuclear cells (PBMCs) using fluorescence‐activated cell sorting analysis. Monocytes [CD14‐phycoerythrin (PE) antibody (Ab) positive (+) cells, 10–15% of PBMCs] all (98–100%) co‐labelled with Hu‐OPGL‐F (n > 18). T lymphocytes (CD3‐PE Ab+ cells, 66% of PBMCs) did not bind Hu‐OPGL‐F; however, B cells (CD19‐PE Ab+ cells, 9% of PBMCs) were also positive for Hu‐OPGL‐F. All Hu‐OPGL‐F+ monocytes also co‐labelled with CD33, CD61, CD11b, CD38, CD45 and CD54 Abs, but not CD34 or CD56 Abs. Hu‐OPGL‐F binding was dose dependent and competed with excess Hu‐OPGL. When Hu‐OPGL‐F+, CD14‐PE Ab+, CD33‐PE Ab+, Hu‐OPGL‐F+/CD14‐PE Ab+ or Hu‐OPGL‐F+/CD33‐PE Ab+ cells were cultured with OPGL (20 ng/ml) and colony‐stimulating factor (CSF)‐1 (25 ng/ml), OC‐like cells readily developed. Thus, all freshly isolated monocytes demonstrate displaceable Hu‐OPGL‐F binding, suggesting the presence of RANK on OCPs in PB; also, OCPs within a purified PB monocyte population form osteoclast‐like cells in the complete absence of other cell types in OPGL and CSF‐1 containing medium.

Genotype–phenotype correlation in MYH9‐related thrombocytopenia

Mutation of the non‐muscle myosin heavy chain type II‐A results in MYH9‐related hereditary macrothrombocytopenia (HMTC), including four autosomal dominant platelet disorders: May‐Hegglin anomaly (MHA), Sebastian (SBS), Fechtner (FS) and Epstein (EPS) syndrome. Denaturing high‐performance liquid chromatography (DHPLC) was optimised for rapid screening of the seven exons harbouring all but one of the previously reported mutations of MYH9. Individuals from 13 families with phenotypes suggestive of MYH9‐related HMTC were screened for mutations by DHPLC followed by direct sequencing of samples with aberrant column retention time. Mutations were identified in all 13 families. Six distinct missense heterozygous mutations were found in 10 families, including six families with MHA or SBS (E1841K, D1424N), three families with FS (R702H, R1165C, and D1424Y), and one family with EPS (S96L). A truncating mutation (R1933X) was found in three MHA families. A review of all published mutations suggests that mutation in the C‐terminal coiled coil region or truncation of the tailpiece is associated with haematological‐only phenotype, while mutation of the head ATPase domain frequently is associated with nephropathy and/or hearing loss. Mutations of other regions have intermediate expression of non‐haematological characteristics. Further study is required to confirm these associations and understand the molecular basis for this genotype–phenotype relationship.

Mouse models of MYH9-related disease: mutations in nonmuscle myosin II-A

We have generated 3 mouse lines, each with a different mutation in the nonmuscle myosin II-A gene, Myh9 (R702C, D1424N, and E1841K). Each line develops MYH9-related disease similar to that found in human patients. R702C mutant human cDNA fused with green fluorescent protein was introduced into the first coding exon of Myh9, and D1424N and E1841K mutations were introduced directly into the corresponding exons. Homozygous R702C mice die at embryonic day 10.5-11.5, whereas homozygous D1424N and E1841K mice are viable. All heterozygous and homozygous mutant mice show macrothrombocytopenia with prolonged bleeding times, a defect in clot retraction, and increased extramedullary megakaryocytes. Studies of cultured megakaryocytes and live-cell imaging of megakaryocytes in the BM show that heterozygous R702C megakaryocytes form fewer and shorter proplatelets with less branching and larger buds. The results indicate that disrupted proplatelet formation contributes to the macrothrombocytopenia in mice and most probably in humans. We also observed premature cataract formation, kidney abnormalities, including albuminuria, focal segmental glomerulosclerosis and progressive kidney disease, and mild hearing loss. Our results show that heterozygous mice with mutations in the myosin motor or filament-forming domain manifest similar hematologic, eye, and kidney phenotypes to humans with MYH9-related disease.

Carbonic anhydrase IX in early-stage non-small cell lung cancer.

Purpose: Tumor hypoxia is associated with poor prognosis and increased tumor aggressiveness. Carbonic anhydrase (CA) IX, an endogenous marker for tumor hypoxia, catalyzes the hydration of carbon dioxide into carbonic acid and contributes to the pH regulation of tumor cells. Therefore, CA IX might allow tumors to acclimate to a hypoxic microenvironment, promoting tumor cell proliferation. We hypothesized that CA IX expression is related to tumor cell proliferation and poor disease-free survival in patients with early-stage non–small-cell lung cancer (NSCLC). Experimental Design: CA IX expression was measured in 75 resected NSCLC tumors to assess prognostic implications for disease-free survival. The relationship of CA IX expression with microvessel density (MVD) and proliferation (Ki-67) index was assessed via colocalization analysis. Results: All patients had operable NSCLC (stage I, 58; stage II, 17). CA IX expression was present in 54 (72%) of 75 patients and was associated with tumor necrosis (P < 0.05). CA IX-positive tumor areas showed greater cell proliferation as measured by Ki-67 index (P < 0.05) and less MVD (P < 0.05) than did CA IX-negative areas in colocalization analysis. The percentage of CA IX-positive tumor cells was significantly related to postoperative recurrence and poor disease-free survival (P < 0.05). Ki-67 index and pathologic stage were also independent prognostic factors for worse disease-free survival (P < 0.05). Conclusions: CA IX expression of tumor cells may be an indicator for poor disease-free survival in early-stage NSCLC.