Background: The hypoxia marker pimonidazole is a candidate biomarker of cancer aggressiveness. We investigated the transcriptional programme associated with pimonidazole staining in prostate cancer. Methods: Index tumour biopsies were taken by image guidance from an investigation cohort of 52 patients, where 43 patients received pimonidazole before prostatectomy. Biopsy location within the index tumour was verified for 46 (88%) patients, who were included for gene expression profiling and immunohistochemistry. Two independent cohorts of 59 and 281 patients were used for validation. Results: Expression of genes in proliferation, DNA repair and hypoxia response was a major part of the transcriptional programme associated with pimonidazole staining. A signature of 32 essential genes was constructed and showed positive correlation to Ki67 staining, confirming the increased proliferation in hypoxic tumours as suggested from the gene data. Positive correlations were also found to tumour stage and lymph node status, but not to blood prostate-specific antigen level, consistent with the findings for pimonidazole staining. The association with aggressiveness was confirmed in validation cohorts, where the signature correlated with Gleason score and had independent prognostic impact, respectively. Conclusions: Pimonidazole staining reflects an aggressive hypoxic phenotype of prostate cancer characterised by upregulation of proliferation, DNA repair and hypoxia response genes.

Hypoxia arises in tumor regions with insufficient oxygen supply and is a major barrier in cancer treatment. The distribution of hypoxia levels is highly heterogeneous, ranging from mild, almost non-hypoxic, to severe and anoxic levels. The individual hypoxia levels induce a variety of biological responses that impair the treatment effect. A stronger focus on hypoxia levels rather than the absence or presence of hypoxia in our investigations will help development of improved strategies to treat patients with hypoxic tumors. Current knowledge on how hypoxia levels are sensed by cancer cells and mediate cellular responses that promote treatment resistance is comprehensive. Recently, it has become evident that hypoxia also has an important, more unexplored role in the interaction between cancer cells, stroma and immune cells, influencing the composition and structure of the tumor microenvironment. Establishment of how such processes depend on the hypoxia level requires more advanced tumor models and methodology. In this review, we describe promising model systems and tools for investigations of hypoxia levels in tumors. We further present current knowledge and emerging research on cellular responses to individual levels, and discuss their impact in novel therapeutic approaches to overcome the hypoxia barrier.

The BJC is owned by Cancer Research UK, a charity dedicated to understanding the causes, prevention and treatment of cancer and to making sure that the best new treatments reach patients in the clinic as quickly as possible. The journal reflects these aims. It was founded more than fifty years ago and, from the start, its far-sighted mission was to encourage communication of the very best cancer research from laboratories and clinics in all countries. The breadth of its coverage, its editorial independence and it consistent high standards, have made BJC one of the world's premier general cancer journals. Its increasing popularity is reflected by a steadily rising impact factor.

Knowledge of the molecular background of functional magnetic resonance (MR) images is required to fully exploit their potential in cancer management. We explored the prognostic impact of dynamic contrast-enhanced MR imaging (DCE-MRI) parameters in cervical cancer combined with global gene expression data to reveal their underlying molecular phenotype and construct a representative gene signature for the relevant parameter. On the basis of 78 patients with cervical cancer subjected to curative chemoradiotherapy, we identified the prognostic DCE-MRI parameter A_Brix by pharmacokinetic analysis of pretreatment images based on the Brix model, in which tumors with low A_Brix appeared to be most aggressive. Gene set analysis of 46 tumors with pairwise DCE-MRI and gene expression data showed a significant correlation between A_Brix and the hypoxia gene sets, whereas gene sets related to other tumor phenotypes were not significant. Hypoxia gene sets specific for cervical cancer created in cell culture experiments, including both targets of the hypoxia inducible factor (HIF1α) and the unfolded protein response, were the most significant. In the remaining 32 tumors, low A_Brix was associated with upregulation of HIF1α protein expression, as assessed by immunohistochemistry, consistent with increased hypoxia. On the basis of the hypoxia gene sets, a signature of 31 genes that were upregulated in tumors with low A_Brix was constructed. This DCE-MRI hypoxia gene signature showed prognostic impact in an independent validation cohort of 109 patients. Our findings reveal the molecular basis of an aggressive hypoxic phenotype and suggest the use of DCE-MRI to noninvasively identify patients with hypoxia-related chemoradioresistance. Cancer Res; 72(20); 5285–95. ©2012 AACR.

Some clinical studies involving several histological types of cancer have suggested that high vascular density in the primary tumour promotes metastasis. Other studies have suggested that a high incidence of metastases is associated with low oxygen tension in the primary tumour. The purpose of the study reported here was to search for correlations between incidence of metastases and oxygen tension or vascular density in the same population of patients. Thirty-eight consecutive patients with squamous cell carcinoma of the uterine cervix were included in a prospective study. Pelvic, iliac and retroperitoneal lymph node metastases were detected by magnetic resonance imaging at the time of initial diagnosis. Oxygen tension was measured polarographically using the Eppendorf pO2 Histograph 6650. Vascular density was determined by histological examination of tumour biopsies. The primary tumours of the patients with metastases (n = 19) were more poorly oxygenated than those of the patients without metastases (n = 19). Thus, the fractions of the pO2 readings resulting in values below 5 mmHg and 10 mmHg were significantly higher for the former group of patients than for the latter (P = 0.03 and 0.02 respectively). In contrast, the vascular density of the primary tumour was not significantly different for the two groups of patients. The present study suggests that a high incidence of metastases in squamous cell carcinoma of the uterine cervix is associated with poor oxygenation of the primary tumour and not with a high vascular density.

A better understanding of the development of metastatic disease and the identification of molecular markers for cancer spread would be useful for the design of improved treatment strategies. This study was conducted to identify gene expressions associated with metastatic phenotypes of locally advanced cervical carcinomas and investigate whether gains or losses of these genes could play a role in regulation of the transcripts. Gene expressions and copy number changes were determined in primary tumors from 29 patients with and 19 without diagnosed lymph node metastases by use of cDNA and genomic microarray techniques, respectively. Thirty-one genes that differed in expression between the node positive and negative tumors were identified. Expressions of eight of these genes (MRPL11, CKS2, PDK2, MRPS23, MSN, TBX3, KLF3, LSM3) correlated with progression free survival in univariate analysis and were therefore more strongly associated with metastatic phenotypes than the others. Immunohistochemistry data of CKS2 and MSN showed similar relationships to survival. The prognostic genes clustered into two groups, suggesting two major metastatic phenotypes. One group was associated with rapid proliferation, oxidative phosphorylation, invasiveness, and tumor size (MRPS23, MRPL11, CKS2, LSM3, TBX3, MSN) and another with hypoxia tolerance, anaerobic metabolism, and high lactate content (PDK2, KLF3). Multivariate analysis identified tumor volume and PDK2 expression as independent prognostic variables. Gene copy number changes of the differentially expressed genes were not frequent, but correlated with the expression level for seven genes, including MRPS23, MSN, and LSM3. Gene expressions associated with known metastatic phenotypes of cervical cancers were identified. Our findings may indicate molecular mechanisms underlying development of these phenotypes and be useful as markers of cancer spread. Gains or losses of the genes may be involved in development of the metastatic phenotypes in some cases, but other mechanisms for transcriptional regulation are probably important in the majority of tumors.