Hypoxia-inducible factor 1alpha expression as an intrinsic marker of hypoxia: correlation with tumor oxygen, pimonidazole measurements, and outcome in locally advanced carcinoma of the cervix

Differential expression of HIF1A and its downstream target VEGFA in the main subtypes of renal cell carcinoma and their impact on patient survival

Renal cell carcinoma (RCC) represents around 3% of all cancers, with the most frequent histological types being clear-cell RCC (ccRCC), followed by papillary (pRCC) and chromophobe (chRCC). Hypoxia-inducible factors (HIFs), which promote the expression of various target genes, including vascular endothelial growth factor (VEGF) and the high- affinity glucose transporter 1, have an important role in the pathogenesis of RCC. This study investigated the immunohistochemical expression of HIF-1α and VEGF-A, showing significantly higher HIF-1α nuclear expression in pRCC compared to ccRCC, while there was no significant difference in VEGF-A protein expression between the analyzed histological RCC subtypes. The quantitative reverse transcription polymerase chain reaction for HIF1A showed no statistical difference between histological types. Data from publicly available RNA sequencing databases were analyzed and showed that, compared to healthy kidney tissue, VEGFA was significantly up-regulated in ccRCC and significantly down-regulated in pRCC. The comparison between histological subtypes of RCC revealed that VEGFA was significantly up-regulated in ccRCC compared to both pRCC and chRCC. There was no statistically significant difference in survival time between HIF1A high- and low-expression groups of patients. As for VEGFA expression, pRCC patients with low expression had a significantly higher survival rate compared to patients with high VEGFA expression.

Prognostic histological markers in oral tongue squamous cell carcinoma patients treated with (chemo)radiotherapy

Treatment of oral tongue squamous cell carcinoma (OTSCC) frequently includes surgery with postoperative radiotherapy (RT) or chemoradiotherapy (CRT). Resistance to RT or CRT remains a major clinical challenge and highlights the need to identify predictive markers for it. We included 71 OTSCC patients treated with surgery combined with RT or CRT. We evaluated the association between tumor budding, tumor-stroma ratio (TSR), depth of invasion (DOI), tumor-infiltrating lymphocytes (TILs), hypoxia-inducible factor-1alpha (HIF-1alpha) expression, octamer-binding transcription factor 4 (OCT4) expression, high-endothelial venules (HEVs), and disease-free survival (DFS) using uni- and multivariate analyses. No significant association was observed between the different histological and molecular markers (TSR, DOI, TILs, HEV, HIF-1alph, OCT4) and DFS. However, an associative trend between DOI, budding, and DFS was noted. Further studies with larger cohorts are needed to explore the prognostic value of DOI and budding for OTSCC patients treated with postoperative RT or CRT.

Pyrrolyl and Indolyl α-γ-Diketo Acid Derivatives Acting as Selective Inhibitors of Human Carbonic Anhydrases IX and XII

Solid tumors are active tissues containing hypoxic regions and producing metabolic acids. By decreasing pH, cancer cells create a hostile environment for surrounding host cells and foster tumor growth and progression. By governing acid/base regulation, carbonic anhydrases (CAs) are involved in several physiological/pathological processes, including tumors. Indeed, CAs are clinically relevant in cancer therapy as among the fifteen human isoforms, two of them, namely CA IX (overexpressed in solid tumors and associated with increased metastasis and poor prognosis) and CA XII (overexpressed in some tumors) are involved in tumorigenesis. Targeting these two isoforms is considered as a pertinent approach to develop new cancer therapeutics. Several CA inhibitors (CAIs) have been described, even though they are unselective inhibitors of different isoforms. Thus, efforts are needed to find new selective CAIs. In this work, we described new diketo acid derivatives as CAIs, with the best acting compounds 1c and 5 as nanomolar inhibitors of CA IX and XII, being also two orders of magnitude selective over CAs I and II. Molecular modeling studies showed the different binding poses of the best acting CAIs within CA II and IX, highlighting the key structural features that could confer the ability to establish specific interactions within the enzymes. In different tumor cell lines overexpressing CA IX and XII, the tested compounds showed antiproliferative activity already at 24 h treatment, with no effects on somatic not transformed cells.

The relevance between hypoxia-dependent spatial transcriptomics and the prognosis and efficacy of immunotherapy in claudin-low breast cancer

Introduction

Hypoxia is an important characteristic of solid tumors. However, spatial transcriptomics (ST) of hypoxia-associated heterogeneity is not clear.

Methods

This study integrated Spatial Transcriptomics (ST) with immunofluorescence to demonstrate their spatial distribution in human claudin-low breast cancer MDA-MB-231 engraft. ST spots were clustered with differentially expression genes. The data were combined with hypoxia-specific marker and angiogenesis marker-labeled serial sections to indicate the spatial distribution of hypoxia and hypoxia-inducted transcriptional profile. Moreover, marker genes, cluster-specific hypoxia genes, and their co-essential relationship were identified and mapped in every clusters. The clinicopathological association of marker genes of hypoxia-dependent spatial clusters was explored in 1904 breast cancers from METABRIC database.

Results

The tumor from center to periphery were enriched into five hypoxia-dependent subgroups with differentially expressed genes, which were matched to necrosis, necrosis periphery, hypoxic tumor, adaptive survival tumor, and invasive tumor, respectively. Different subgroups demonstrated distinct hypoxia condition and spatial heterogeneity in biological behavior and signaling pathways. Cox regression analysis showed that the invasive tumor (cluster 0) and hypoxic tumor (cluster 6) score could be served as independent prognostic factors in claudin-low patients. KM analysis indicated that high invasive tumor (cluster 0) and hypoxic tumor (cluster 6) score was associated with poor prognoses of claudin-low patients. Further analysis showed that hypoxia-induced immune checkpoints, such as CD276 and NRP1, upregulation in invasive tumor to block infiltration and activation of B cells and CD8+ T cells to change tumor immune microenvironment.

Discussion

This study reveals hypoxia-dependent spatial heterogeneity in claudin-low breast cancer and highlights its potential value as a predictive biomarker of clinical outcomes and immunotherapy response. The molecules found in this study also provided potential molecular mechanisms and therapeutic targets for subsequent studies.

Targeting hypoxia in solid and haematological malignancies

Tumour hypoxia is a known and extensively researched phenomenon that occurs in both solid and haematological malignancies. As cancer cells proliferate, demand for oxygen can outstrip supply reducing tumour oxygenation. In solid tumours this is contributed to by disorganized blood vessel development. Tumour hypoxia is associated with resistance to treatment, more aggressive disease behaviour and an increased likelihood of metastatic progression. It can be measured using both invasive and non-invasive methods to varying degrees of accuracy. The presence of hypoxia stimulates a complex cellular network of downstream factors including Hypoxia Inducible Factor 1 (HIF1), C-X-C motif chemokine 4 (CXCR4) and Hypoxia‐inducible glycolytic enzyme hexokinase‐2 (HK2) amongst many others. They work by affecting different mechanisms including influencing angiogenesis, treatment resistance, immune surveillance and the ability to metastasize all of which contribute to a more aggressive disease pattern. Tumour hypoxia has been correlated with poorer outcomes and worse prognosis in patients. The correlation between hypoxic microenvironments and poor prognosis has led to an interest in trying to therapeutically target this phenomenon. Various methods have been used to target hypoxic microenvironments. Hypoxia-activated prodrugs (HAPs) are drugs that are only activated within hypoxic environments and these agents have been subject to investigation in several clinical trials. Drugs that target downstream factors of hypoxic environments including HIF inhibitors, mammalian target of rapamycin (mTOR) inhibitors and vascular endothelial growth factor (anti-VEGF) therapies are also in development and being used in combination in clinical trials. Despite promising pre-clinical data, clinical trials of hypoxia targeting strategies have proven challenging. Further understanding of the effect of hypoxia and related molecular mechanisms in human rather than animal models is required to guide novel therapeutic strategies and future trial design. This review will discuss the currently available methods of hypoxia targeting and assessments that may be considered in planning future clinical trials. It will also outline key trials to date in both the solid and haemato-oncology treatment spheres and discuss the limitations that may have impacted on clinical success to date.

Bioengineered 3D Tissue Model of Intestine Epithelium with Oxygen Gradients to Sustain Human Gut Microbiome

The human gut microbiome is crucial to hosting physiology and health. Therefore, stable in vitro coculture of primary human intestinal cells with a microbiome community is essential for understanding intestinal disease progression and revealing novel therapeutic targets. Here, a three-dimensional scaffold system is presented to regenerate an in vitro human intestinal epithelium that recapitulates many functional characteristics of the native small intestines. The epithelium, derived from human intestinal enteroids, contains mature intestinal epithelial cells and possesses selectively permeable barrier functions. Importantly, by properly positioning the scaffolds cultured under normal atmospheric conditions, two physiologically relevant oxygen gradients, a proximal-to-distal oxygen gradient along the gastrointestinal (GI) tract, and a radial oxygen gradient across the epithelium, are distinguished in the tissues when the lumens are faced up and down in cultures, respectively. Furthermore, the presence of the low oxygen gradients supported the coculture of intestinal epithelium along with a complex living commensal gut microbiome (including obligate anaerobes) to simulate temporal microbiome dynamics in the native human gut. This unique silk scaffold platform may enable the exploration of microbiota-related mechanisms of disease pathogenesis and host-pathogen dynamics in infectious diseases including the potential to explore the human microbiome-gut-brain axis and potential novel microbiome-based therapeutics.

Correlation and colocalization of HIF-1α and pimonidazole staining for hypoxia in laryngeal squamous cell carcinomas: A digital, single-cell-based analysis

OBJECTIVE

Tumor hypoxia results in worse local control and patient survival. We performed a digital, single-cell-based analysis to compare two biomarkers for hypoxia (hypoxia-inducible factor 1-alpha [HIF-1α] and pimonidazole [PIMO]) and their effect on outcome in laryngeal cancer patients treated with accelerated radiotherapy with or without carbogen breathing and nicotinamide (AR versus ARCON).

MATERIALS AND METHODS

Immunohistochemical staining was performed for HIF-1α and PIMO in consecutive sections of 44 laryngeal cancer patients randomized between AR and ARCON. HIF-1α expression and PIMO-binding were correlated using digital image analysis in QuPath. High-density areas for each biomarker were automatically annotated and staining overlap was analyzed. Kaplan-Meier survival analyses for local control, regional control and disease-free survival were performed to predict a response benefit of ARCON over AR alone for each biomarker.

RESULTS

106 Tissue fragments of 44 patients were analyzed. A weak, significant positive correlation was observed between HIF-1α and PIMO positivity on fragment level, but not on patient level. A moderate strength correlation (r = 0.705, p < 0.001) was observed between the number of high-density staining areas for both biomarkers. Staining overlap was poor. HIF-1α expression, PIMO-binding or a combination could not predict a response benefit of ARCON over AR.

CONCLUSION

Digital image analysis to compare positive cell fractions and staining overlap between two hypoxia biomarkers using open-source software is feasible. Our results highlight that there are distinct differences between HIF-1α and PIMO as hypoxia biomarkers and therefore suggest co-existence of different forms of hypoxia within a single tumor.

The three-tails approach as a new strategy to improve selectivity of action of sulphonamide inhibitors against tumour-associated carbonic anhydrase IX and XII

Human (h) carbonic anhydrase (CAs, EC 4.2.1.1) isoforms IX and XII were recently confirmed as anticancer targets against solid hypoxic tumours. The “three-tails approach” has been proposed as an extension of the forerunner “tail” and “dual-tail approach” to fully exploit the amino acid differences at the medium/outer active site rims among different hCAs and to obtain more isoform-selective inhibitors. Many three-tailed inhibitors (TTIs) showed higher selectivity against the tumour-associated isoforms hCA IX and XII with respect to the off-targets hCA I and II. X-ray crystallography studies were performed to investigate the binding mode of four TTIs in complex with a hCA IX mimic. The ability of the most potent and selective TTIs to reduce in vitro the viability of colon cancer (HT29), prostate adenocarcinoma (PC3), and breast cancer (ZR75-1) cell lines was evaluated in normoxic (21% O₂) and hypoxic (3% O₂) conditions demonstrating relevant anti-proliferative effects.

Impact of hypoxia on cervical cancer outcomes

The annual global incidence of cervical cancer is approximately 604 000 cases/342 000 deaths, making it the fourth most common cancer in women. Cervical cancer is a major healthcare problem in low and middle income countries where 85% of new cases and deaths occur. Secondary prevention measures have reduced incidence and mortality in developed countries over the past 30 years, but cervical cancer remains a major cause of cancer deaths in women. For women who present with Fédération Internationale de Gynécologie et d'Obstétrique (FIGO 2018) stages IB3 or upwards, chemoradiation is the established treatment. Despite high rates of local control, overall survival is less than 50%, largely due to distant relapse. Reducing the health burden of cervical cancer requires greater individualization of treatment, identifying those at risk of relapse and progression for modified or intensified treatment. Hypoxia is a well known feature of solid tumors and an established therapeutic target. Low tumorous oxygenation increases the risk of local invasion, metastasis and treatment failure. While meta-analyses show benefit, many individual trials targeting hypoxia failed in part due to not selecting patients most likely to benefit. This review summarizes the available hypoxia-targeted strategies and identifies further research and new treatment paradigms needed to improve patient outcomes. The applications and limitations of hypoxia biomarkers for treatment selection and response monitoring are discussed. Finally, areas of greatest unmet clinical need are identified to measure and target hypoxia and therefore improve cervical cancer outcomes.

Engineering Tools for Regulating Hypoxia in Tumour Models

Major advances in the field of genomic technologies have led to an improvement in cancer diagnosis, classification and prognostication. However, many cancers remain incurable due to the development of drug resistance, minimal residual disease (MRD) and disease relapse, highlighting an incomplete understanding of the mechanisms underlying these processes. In recent years, the impact of non-genetic factors on neoplastic transformations has increasingly been acknowledged, and growing evidence suggests that low oxygen (O2 ) levels (ie hypoxia) in the tumour microenvironment play a critical role in the development and treatment of cancer. As a result, there is a growing need to develop research tools capable of reproducing physiologically relevant O2 conditions encountered by cancer cells in their natural environments in order to gain in-depth insight into tumour cell metabolism and function. In this review, the authors highlight the importance of hypoxia in the pathogenesis of malignant diseases and provide an overview of novel engineering tools that have the potential to further drive this evolving, yet technically challenging, field of cancer research.

Impact of hypoxia on DNA repair and genome integrity

Hypoxia is a hallmark of the tumour microenvironment with profound effects on tumour biology, influencing cancer progression, the development of metastasis and patient outcome. Hypoxia also contributes to genomic instability and mutation frequency by inhibiting DNA repair pathways. This review summarises the diverse mechanisms by which hypoxia affects DNA repair, including suppression of homology-directed repair, mismatch repair and base excision repair. We also discuss the effects of hypoxia mimetics and agents that induce hypoxia on DNA repair, and we highlight areas of potential clinical relevance as well as future directions.

Tumor Hypoxia as a Barrier in Cancer Therapy: Why Levels Matter

Simple Summary

Hypoxia is a common feature of solid tumors and associated with poor outcome in most cancer types and treatment modalities, including radiotherapy, chemotherapy, surgery and, most likely, immunotherapy. Emerging strategies, such as proton therapy and combination therapies with radiation and hypoxia targeted drugs, provide new opportunities to overcome the hypoxia barrier and improve therapeutic outcome. Hypoxia is heterogeneously distributed both between and within tumors and shows large variations across patients not only in prevalence, but importantly, also in level. To best exploit the emerging strategies, a better understanding of how individual hypoxia levels from mild to severe affect tumor biology is vital. Here, we discuss our current knowledge on this topic and how we should proceed to gain more insight into the field.

Abstract

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.

Retooling Cancer Nanotherapeutics' Entry into Tumors to Alleviate Tumoral Hypoxia

Anti-hypoxia cancer nanomedicine (AHCN) holds exciting potential in improving oxygen-dependent therapeutic efficiencies of malignant tumors. However, most studies regarding AHCN focus on optimizing structure and function of nanomaterials with presupposed successful entry into tumor cells. From such a traditional perspective, the main barrier that AHCN needs to overcome is mainly the tumor cell membrane. However, such an oversimplified perspective would neglect that real tumors have many biological, physiological, physical, and chemical defenses preventing the current state-of-the-art AHCNs from even reaching the targeted tumor cells. Fortunately, in recent years, some studies are beginning to intentionally focus on overcoming physiological barriers to alleviate hypoxia. In this Review, the limitations behind the traditional AHCN delivery mindset are addressed and the key barriers that need to be surmounted before delivery to cancer cells and some good ways to improve cell membrane attachment, internalization, and intracellular retention are summarized. It is aimed to contribute to Review literature on this emerging topic through refreshing perspectives based on this work and what is also learnt from others. This Review would therefore assist AHCNs researchers to have a quick overview of the essential information and glean thought-provoking ideas to advance this sub-field in cancer nanomedicine.

Synthesis and evaluation of indium-111-labeled imidazothiadiazole sulfonamide derivative for single photon emission computed tomography imaging targeting carbonic anhydrase-IX

Carbonic anhydrase-IX (CA-IX) is a zinc enzyme overexpressed in the hypoxic regions of many types of solid tumors; therefore, in vivo imaging of CA-IX may contribute to cancer diagnosis. In this study, we newly designed and synthesized an ¹¹¹In-labeled CA-IX imaging agent based on an imidazothiadiazole sulfonamide (IS) scaffold conjugated with a chelating moiety, DO3A ([¹¹¹In]DO3A-IS1), and evaluated its utility for imaging of CA-IX high-expressing tumors. [¹¹¹In]DO3A-IS1 was successfully synthesized at a 76% radiochemical yield by reacting its precursor with ¹¹¹InCl₃ in acetate buffer. In in vitro assays, [¹¹¹In]DO3A-IS1 showed marked stability in murine plasma and greater binding to CA-IX high-expressing (HT-29) cells (118 ± 21% initial dose/mg protein) than CA-IX low-expressing (MDA-MB-231) cells (1.4 ± 0.3% initial dose/mg protein). Moreover, in an in vivo biodistribution assay, [¹¹¹In]DO3A-IS1 showed marked accumulation in the HT-29 tumor (8.71 ± 1.41% injected dose/g at 24 h postinjection). In addition, in a single photon emission computed tomography (SPECT) study, [¹¹¹In]DO3A-IS1 clearly and selectively visualized the HT-29 tumor as compared with the MDA-MB-231 tumor. These results indicate that [¹¹¹In]DO3A-IS1 may serve as a useful SPECT imaging agent with the novel scaffold targeting CA-IX.

Protein Hydroxylation by Hypoxia-Inducible Factor (HIF) Hydroxylases: Unique or Ubiquitous?

All metazoans that utilize molecular oxygen (O₂) for metabolic purposes have the capacity to adapt to hypoxia, the condition that arises when O₂ demand exceeds supply. This is mediated through activation of the hypoxia-inducible factor (HIF) pathway. At physiological oxygen levels (normoxia), HIF-prolyl hydroxylases (PHDs) hydroxylate proline residues on HIF-α subunits leading to their destabilization by promoting ubiquitination by the von-Hippel Lindau (VHL) ubiquitin ligase and subsequent proteasomal degradation. HIF-α transactivation is also repressed in an O₂-dependent way due to asparaginyl hydroxylation by the factor-inhibiting HIF (FIH). In hypoxia, the O₂-dependent hydroxylation of HIF-α subunits by PHDs and FIH is reduced, resulting in HIF-α accumulation, dimerization with HIF-β and migration into the nucleus to induce an adaptive transcriptional response. Although HIFs are the canonical substrates for PHD- and FIH-mediated protein hydroxylation, increasing evidence indicates that these hydroxylases may also have alternative targets. In addition to PHD-conferred alterations in protein stability, there is now evidence that hydroxylation can affect protein activity and protein/protein interactions for alternative substrates. PHDs can be pharmacologically inhibited by a new class of drugs termed prolyl hydroxylase inhibitors which have recently been approved for the treatment of anemia associated with chronic kidney disease. The identification of alternative targets of HIF hydroxylases is important in order to fully elucidate the pharmacology of hydroxylase inhibitors (PHI). Despite significant technical advances, screening, detection and verification of alternative functional targets for PHDs and FIH remain challenging. In this review, we discuss recently proposed non-HIF targets for PHDs and FIH and provide an overview of the techniques used to identify these.

Development of the 99mTc-Hydroxamamide Complex as a Probe Targeting Carbonic Anhydrase IX

Carbonic anhydrase IX (CA-IX) is regarded as a favorable target for in vivo imaging because of its specific expression in hypoxic regions of tumors. Hypoxia assists tumor propagation and growth and is resistant to chemotherapy and radiotherapy. Here, we designed and synthesized [^99mTc]hydroxamamide ([^99mTc]Ham) and [^99mTc]methyl-substituted-hydroxamamide ([^99mTc]MHam) complexes including a bivalent CA-IX ligand, sulfonamide (SA), and ureidosulfonamide (UR). In a cell binding assay, [^99mTc]Ham complexes with bivalent SA ([^99mTc]SAB2A and [^99mTc]SAB2B) and UR ([^99mTc]URB2A and [^99mTc]URB2B) showed significantly greater uptake into CA-IX high-expressing (HT-29) cells than that into CA-IX low-expressing cells. Since the binding affinity of [^99mTc]URB2A and [^99mTc]URB2B for CA-IX was significantly higher than that of [^99mTc]SAB2A and [^99mTc]SAB2B, we additionally synthesized [^99mTc]MURB2 (a [^99mTc]MHam complex with bivalent UR) and evaluated the CA-IX-specific binding affinity of [^99mTc]URB2A, [^99mTc]URB2B, and [^99mTc]MURB2. Their uptake into HT-29 cells was reduced by the addition of a CA inhibitor, acetazolamide, suggesting their CA-IX-specific binding affinity. A biodistribution study in HT-29 tumor-bearing mice was carried out using [^99mTc]URB2A and [^99mTc]MURB2 with the highest specificity for HT-29 cells. [^99mTc]URB2A showed moderate tumor uptake and reduction by coinjection with acetazolamide; however, the tumor/blood ratio was insufficient for in vivo imaging. These results provided key information for the design of novel Ham-based imaging probes targeting CA-IX.

Cancer radiotheranostics targeting carbonic anhydrase-IX with 111In- and 90Y-labeled ureidosulfonamide scaffold for SPECT imaging and radionuclide-based therapy

Hypoxic cells dynamically translocate during tumor growth and after radiotherapy. The most desirable direction for therapy targeting hypoxic cells is combining imaging and therapy (theranostics), which may help realize personalized medicine. Here, we conducted cancer radiotheranostics targeting carbonic anhydrase-IX (CA-IX), which is overexpressed in many kinds of hypoxic cancer cells, using low-molecular-weight 111In and 90Y complexes with a bivalent ureidosulfonamide scaffold as the CA-IX-binding moiety ([111In/90Y]US2). Methods: The targeting ability of [111In]US2 was evaluated by in vivo biodistribution study in CA-IX high-expressing (HT-29) tumor-bearing mice. In vivo imaging of HT-29 tumors was carried out using single photon emission computed tomography (SPECT). [90Y]US2 was administered to HT-29 tumor-bearing mice to evaluate cancer therapeutic effects. Results: [111In]US2 highly and selectively accumulated within HT-29 tumors (4.57% injected dose/g tumor at 1 h postinjection), was rapidly cleared from the blood pool and muscle after 4 h based on a biodistribution study, and visualized HT-29 tumor xenografts in mice at 4 h postinjection with SPECT. Radionuclide-based therapy with [90Y]US2 significantly delayed HT-29 tumor growth compared with that of untreated mice (P = 0.02 on day 28, Student's t-test), without any critical hematological toxicity due to its rapid pharmacokinetics. Conclusion: These results indicate that cancer radiotheranostics with [111In/90Y]US2 provides a novel strategy of theranostics for cancer hypoxia.

Past, Present, and Future: Development of Theranostic Agents Targeting Carbonic Anhydrase IX

Theranostics is the integration of diagnostic information with pharmaceuticals to increase effectiveness and safety of cancer treatments. Nuclear medicine provides a non-invasive means to visualize drug target expression across primary and metastatic sites, and assess pharmacokinetics and efficacy of companion therapeutic agents. This is significant given the increasing recognition of the importance of clonal heterogeneity in treatment response and resistance. Carbonic anhydrase IX (CA-IX) has been advocated as an attractive diagnostic and therapeutic biomarker for targeting hypoxia in solid malignancies. CA-IX confers cancer cell survival under low oxygen tension, and is associated with increased propensity for metastasis. As such, CA-IX is overexpressed in a broad spectrum of cancers. Different classes of antigen recognition molecules targeting CA-IX including monoclonal antibodies, peptides, small molecule inhibitors, and antibody mimetics have been radiolabeled for imaging and therapeutic applications. cG250, a chimeric monoclonal antibody, has been labeled with an assortment of radionuclides (¹²⁴I, ¹¹¹In, ⁸⁹Zr, ¹³¹I, ⁹⁰Y, and ¹⁷⁷Lu) and is the most extensively investigated CA-IX radiopharmaceutical. In recent years, there have been tremendous advancements made by the research community in developing alternatives to cG250. Although still in preclinical settings, several small molecule inhibitors and antibody mimetics hold great promise in improving the management of aggressive and resistant cancers.

Glut-1 expression in small cervical biopsies is prognostic in cervical cancers treated with chemoradiation

BACKGROUND/PURPOSE

Chemoradiation (CRT) is standard therapy for locally advanced cervical cancer (LACC). However, there is a lack of biomarkers to identify patients at high relapse-risk. We examine metabolic (glucose transporter-1 [Glut-1]), hypoxic (hypoxia inducible factor [HIF-1α]; carbonic anhydrase [CA-9]) and proliferative (Ki-67) markers for prognostic utility in LACC.

MATERIALS/METHODS

60 LACC patients treated with CRT had pre-treatment biopsies. Immunohistochemistry was performed for Glut-1, HIF-1a and CA-9, to generate a histoscore from intensity and percentage staining; and Ki-67 scored by percentage of positive cells. For each biomarker, treatment response and survival was compared between low and high-staining groups by logrank testing and multivariate analyses.

RESULTS

High Glut-1 expression was associated with inferior progression-free survival (PFS), (hazard ratio [HR] 2.8, p = 0.049) and overall survival (OS), (HR 5.0, p = 0.011) on multifactor analysis adjusting for stage, node positivity, tumour volume and uterine corpus invasion. High Glut-1 correlated with increased risk of distant failure (HR 14.6, p = 0.001) but not local failure. Low Glut-1 was associated with higher complete metabolic response rate on post-therapy positron emission tomography scan (odds ratio 3.4, p = 0.048). Ki-67 was significantly associated with PFS only (HR 1.19 per 10 units increase, p = 0.033). Biomarkers for hypoxia were not associated with outcome.

CONCLUSIONS

High Glut-1 in LACC is associated with poor outcome post CRT. If prospectively validated, Glut-1 may help select patients for more intensive treatment regimens.

BMPR2 and HIF1- overexpression in resected osteosarcoma correlates with distant metastasis and patient survival

Objective

Bone morphogenetic protein receptor 2 (BMPR2) and hypoxia-inducible factor 1-α (HIF1-α) existed abnormal expression in several types of cancer. However, their expressions and related roles in osteosarcoma are largely unknown.

Methods

To investigate the clinical significance of BMPR2 and HIF1-α in osteosarcoma, we analyzed their expression levels in 103 osteosarcoma specimens by immunochemistry. Meanwhile, we conducted a follow-up to examine the metastatic behavior and overall survival (OS) of osteosarcoma patients.

Results

Among 103 tissues, 61 cases had BMPR2-positive expression and 57 cases had HIF1-α positive expression. A significant correlation was noticed between BMPR2 and HIF1-α expression in osteosarcoma specimens (P=0.035). Receiver-operating characteristic (ROC) curves were calculated to investigate the predictive value of the two markers in tumor metastasis. By means of univariate and multivariate analysis, BMPR2 and HIF1-α expression, as well as higher tumor grade, were identified as significant risk factors for OS in patients with osteosarcoma. Kaplan-Meier survival analysis revealed that the patients with BMPR2 and HIF1-α positive expression had worse OS compared with patients with BMPR2-negative or HIF1-α-negative staining.

Conclusions

It can be concluded that BMPR2 and HIF1-α expression is highly correlated with metastatic behavior in patients with osteosarcoma and can serve as predictive markers for metastasis and OS of these patients.

Hypoxia in cervical cancer: from biology to imaging

PURPOSE

Hypoxia imaging may improve identification of cervical cancer patients at risk of treatment failure and be utilized in treatment planning and monitoring, but its clinical potential is far from fully realized. Here, we briefly describe the biology of hypoxia in cervix tumors of relevance for imaging, and evaluate positron emission tomography (PET) and magnetic resonance imaging (MRI) techniques that have shown promise for assessing hypoxia in a clinical setting. We further discuss emerging imaging approaches, and how imaging can play a role in future treatment strategies to target hypoxia.

METHODS

We performed a PubMed literature search, using keywords related to imaging and hypoxia in cervical cancer, with a particular emphasis on studies correlating imaging with other hypoxia measures and treatment outcome.

RESULTS

Only a few and rather small studies have utilized PET with tracers specific for hypoxia, and no firm conclusions regarding preferred tracer or clinical potential can be drawn so far. Most studies address indirect hypoxia imaging with dynamic contrast-enhanced techniques. Strong evidences for a role of these techniques in hypoxia imaging have been presented. Pre-treatment images have shown significant association to outcome in several studies, and images acquired during fractionated radiotherapy may further improve risk stratification. Multiparametric MRI and multimodality PET/MRI enable combined imaging of factors of relevance for tumor hypoxia and warrant further investigation.

CONCLUSIONS

Several imaging approaches have shown promise for hypoxia imaging in cervical cancer. Evaluation in large clinical trials is required to decide upon the optimal modality and approach.

Reengineering the Tumor Microenvironment to Alleviate Hypoxia and Overcome Cancer Heterogeneity

Solid tumors consist of cancer cells and stromal cells, including resident and transiting immune cells-all ensconced in an extracellular matrix (ECM)-nourished by blood vessels and drained by lymphatic vessels. The microenvironment constituents are abnormal and heterogeneous in morphology, phenotype, and physiology. Such irregularities include an inefficient tumor vascular network comprised of leaky and compressed vessels, which impair blood flow and oxygen delivery. Low oxygenation in certain tumor regions-or focal hypoxia-is a mediator of cancer progression, metastasis, immunosuppression, and treatment resistance. Thus, repairing an abnormal and heterogeneous microenvironment-and hypoxia in particular-can significantly improve treatments of solid tumors. Here, we summarize two strategies to reengineer the tumor microenvironment (TME)-vessel normalization and decompression-that can alleviate hypoxia. In addition, we discuss how these two strategies alone and in combination with each other-or other therapeutic strategies-may overcome the challenges posed by cancer heterogeneity.

Correlation of volumetric perfusion CT parameters with hypoxia inducible factor-1 alpha expression in a rabbit VX2 tumor model

BACKGROUND

Hypoxia inducible factor-1 alpha (HIF-1α) plays a critical role in tumoral angiogenesis and HIF-1α overexpression is associated with an increased risk of patient mortality in many cancers. A number of studies have introduced perfusion computed tomography (CT) as a monitoring modality for antiangiogenic therapy.

PURPOSE

To investigate significance of volumetric perfusion CT parameters in relationship to HIF-1α expression in VX2 tumor rabbit models.

MATERIAL AND METHODS

Twenty VX2 carcinoma tumors of bilateral back muscles of 10 rabbits were evaluated with serial volumetric perfusion CT in 7, 10, and 14 days after tumor implantation. CT perfusion data were analyzed to calculate blood flow (BF), blood volume (BV), and permeability surface area product (PS) of whole tumor and non-necrotic peripheral area (periphery). Immunohistochemical analysis of HIF-1α expression and microvessel density (MVD) was performed.

RESULTS

HIF-1α was expressed in 12 tumors; two, three, and seven tumors classified as scores 1, 2 and 3, respectively. Mean MVD was 24.85 ± 13.7. PS of both the whole tumor and periphery showed positive correlations with HIF-1α score (r = 0.41, P = 0.046; r = 0.43, P = 0.002, respectively). BV of periphery showed a negative correlation with HIF-1α (r = -0.48, P = 0.040). There was strong positive correlation between HIF-1α expression and MVD (r = 0.82, P < 0.001).

CONCLUSION

In VX2 tumors, volumetric perfusion CT parameters were of limited value for the prediction of HIF-1α activity although HIF-1α expression was found to be weakly positively correlated with PS and negatively correlated with BV.

Expression of VEGF and HIF-1α in locally advanced cervical cancer: potential biomarkers for predicting preoperative radiochemotherapy sensitivity and prognosis

Locally advanced cervical cancer (LACC) is an early-stage cervical cancer characterized by a local tumor diameter of ≥4 cm. Patients with LACC have a relatively poor prognosis. Although preoperative radiochemotherapy (PRCT) might offer a valuable opportunity for subsequent radical surgery, surgeons should also consider the nonresponsive rate, the adverse effects of PRCT, and the surgical complications before designing a treatment plan. Therefore, biomarkers for predicting PRCT sensitivity and prognosis in patients with LACC are of high importance. We investigated the prognostic significance of vascular endothelial growth factor (VEGF) and hypoxia inducible factor-1α (HIF-1α) in patients with LACC. A total of 43 patients with LACC who underwent PRCT (one course each of intravenous chemotherapy and after-loading intracavitary brachytherapy followed by a radical hysterectomy) during the period 2009-2014 were included in this study. VEGF and HIF-1α expression levels were evaluated by immunohistochemistry in LACC lesions before and after PRCT. In addition, we analyzed the association of these proteins with the clinical response and pathological findings of pelvic lymph node metastasis (PLNM) after the subsequent surgery. The total clinical response rate was 81.39% after PRCT, including five complete responses and 30 partial responses. VEGF and HIF-1α expression before PRCT was significantly higher than after PRCT (VEGF: 85.71% vs 66.67%; HIF-1α: 83.33% vs 59.52%, P<0.05). In addition, the same trend was found in patients with PLNM compared to those without PLNM (VEGF: 100% vs 77.78%; HIF-1α: 100% vs 74.07%, P<0.05). The areas under the receiver operating characteristic curves were 0.896 and 0.835 when using pre-PRCT VEGF and HIF-1α expression levels, respectively, to diagnose PLNM in patients with LACC. Serial detection of VEGF and HIF-1α demonstrated a sensitivity of 66.67% and specificity of 88.89%. These findings suggest that VEGF and HIF-1α expressions are potential biomarkers for PRCT and have great clinical significance for the prediction of PRCT response and prognosis in patients with LACC.

Hypoxia and metabolic adaptation of cancer cells

Low oxygen tension (hypoxia) is a pervasive physiological and pathophysiological stimulus that metazoan organisms have contended with since they evolved from their single-celled ancestors. The effect of hypoxia on a tissue can be either positive or negative, depending on the severity, duration and context. Over the long-term, hypoxia is not usually consistent with normal function and so multicellular organisms have had to evolve both systemic and cellular responses to hypoxia. Our reliance on oxygen for efficient adenosine triphosphate (ATP) generation has meant that the cellular metabolic network is particularly sensitive to alterations in oxygen tension. Metabolic changes in response to hypoxia are elicited through both direct mechanisms, such as the reduction in ATP generation by oxidative phosphorylation or inhibition of fatty-acid desaturation, and indirect mechanisms including changes in isozyme expression through hypoxia-responsive transcription factor activity. Significant regions of cancers often grow in hypoxic conditions owing to the lack of a functional vasculature. As hypoxic tumour areas contain some of the most malignant cells, it is important that we understand the role metabolism has in keeping these cells alive. This review will outline our current understanding of many of the hypoxia-induced changes in cancer cell metabolism, how they are affected by other genetic defects often present in cancers, and how these metabolic alterations support the malignant hypoxic phenotype.

Differential expression of mitotic regulators and tumor microenvironment influences the regional growth pattern of solid sarcoma along the cranio-caudal axis

Soft tissue sarcomas are relatively rare, unusual, anatomically diverse group of malignancies. According to the recent literature and medical bulletins, tumor growth and aggressiveness immensely relies on its anatomical locations. However, it is unclear whether the cranio-caudal anatomical axis of the mammalian body can influence sarcoma development and the underlying molecular mechanisms are not yet deciphered. Here, we investigated the growth pattern of solid sarcoma implanted into the murine cranial and caudal anatomical locations and tried to explore the location specific expression pattern of crucial mammalian mitotic regulators such as Aurora kinase A, Histone H3 and c-Myc in the cranio-caudally originated solid tumors. In addition, the influence of local tumor microenvironment on regional sarcoma growth was also taken into consideration. We found that solid sarcoma developed differentially when implanted into two different anatomical locations and most notably, enhanced tumor growth was observed in case of cranially implanted sarcoma than the caudal sarcoma. Interestingly, Aurora kinase A and c-Myc expression and histone H3 phosphorylation level were comparatively higher in the cranial tumor than the caudal. In addition, variation of tumor stroma in a location specific manner also facilitated tumor growth. Cranial sarcoma microenvironment was well vascularized than the caudal one and consequently, a significantly higher microvessel density count was observed which was parallel with low hypoxic response with sign of local tumor inflammation in this region. Taken together, our findings suggest that differential gradient of mitotic regulators together with varied angiogenic response and local tumor microenvironment largely controls solid sarcoma growth along the cranio-caudal anatomical axis.

Role of vascular density and normalization in response to neoadjuvant bevacizumab and chemotherapy in breast cancer patients

Preoperative bevacizumab and chemotherapy may benefit a subset of breast cancer (BC) patients. To explore potential mechanisms of this benefit, we conducted a phase II study of neoadjuvant bevacizumab (single dose) followed by combined bevacizumab and adriamycin/cyclophosphamide/paclitaxel chemotherapy in HER2-negative BC. The regimen was well-tolerated and showed a higher rate of pathologic complete response (pCR) in triple-negative (TN)BC (11/21 patients or 52%, [95% confidence interval (CI): 30,74]) than in hormone receptor-positive (HR)BC [5/78 patients or 6% (95%CI: 2,14)]. Within the HRBCs, basal-like subtype was significantly associated with pCR (P = 0.007; Fisher exact test). We assessed interstitial fluid pressure (IFP) and tissue biopsies before and after bevacizumab monotherapy and circulating plasma biomarkers at baseline and before and after combination therapy. Bevacizumab alone lowered IFP, but to a smaller extent than previously observed in other tumor types. Pathologic response to therapy correlated with sVEGFR1 postbevacizumab alone in TNBC (Spearman correlation 0.610, P = 0.0033) and pretreatment microvascular density (MVD) in all patients (Spearman correlation 0.465, P = 0.0005). Moreover, increased pericyte-covered MVD, a marker of extent of vascular normalization, after bevacizumab monotherapy was associated with improved pathologic response to treatment, especially in patients with a high pretreatment MVD. These data suggest that bevacizumab prunes vessels while normalizing those remaining, and thus is beneficial only when sufficient numbers of vessels are initially present. This study implicates pretreatment MVD as a potential predictive biomarker of response to bevacizumab in BC and suggests that new therapies are needed to normalize vessels without pruning.

Hypoxia biomarkers in squamous cell carcinoma of the uterine cervix

Background

There is significant evidence that severe tumor hypoxia may cause resistance to chemoradiotherapy and promote metastatic spread in locally advanced carcinoma of the uterine cervix. Some clinical investigations have suggested that high expression of hypoxia-inducible factor-1α (HIF-1α) and/or its target gene carbonic anhydrase IX (CAIX) may be useful biomarkers of tumor hypoxia and poor outcome in cervical cancer. Here, we challenged this view by investigating possible associations between HIF-1α expression, CAIX expression, fraction of hypoxic tissue, and lymph node metastasis in experimental human tumors.

Methods

Tumors of two cervical carcinoma xenograft lines (CK-160 and TS-415) were included in the study. Pimonidazole was used as a hypoxia marker, and tumor hypoxia, HIF-1α expression, and CAIX expression were detected by immunohistochemistry. Metastatic status was assessed by examining external lymph nodes in the inguinal, axillary, interscapular, and submandibular regions and internal lymph nodes in the abdomen and mediastinum.

Results

Tissue regions staining positive for pimonidazole, HIF-1α, or CAIX were poorly colocalized, both in CK-160 and TS-415 tumors. The expression of HIF-1α or CAIX did not correlate with the fraction of hypoxic tissue in any of the two tumor lines. Furthermore, clinically relevant associations between HIF-1α or CAIX expression and lymph node metastasis were not found.

Conclusion

Because significant associations between HIF-1α expression, CAIX expression, fraction of hypoxic tissue, and incidence of lymph node metastases could not be detected in any of two preclinical models of human cervical cancer, it is not realistic to believe that high expression of HIF-1α or CAIX can be useful biomarkers of tumor hypoxia and poor outcome in a highly heterogeneous disease like cervical carcinoma.

Clinicopathological characteristics of gynecological cancer associated with hypoxia-inducible factor 1α expression: a meta-analysis including 6,612 subjects

BACKGROUND

Gynecological cancer is characterized by tumor hypoxia. However, the role of hypoxia-inducible factor 1α (HIF-1α) in gynecological cancer remains unclear.

METHOD

Electronic databases including Cochrane Library, PUBMED, Web of Knowledge and clinical trial registries were searched from inception through October 2014 for published, case-control studies assessing the association between HIF-1α and the clinicopathological characteristics of gynecological cancer. We pooled results from 59 studies using fixed or random-effects models and present results as odds ratios (ORs) following the PRISMA guidelines.

RESULTS

Our meta-analysis, which included 6,612 women, demonstrated that the expression of HIF-1α was associated with the clinicopathological characteristics of gynecological cancer. The expression of HIF-1α in cancer or borderline tissue was significantly higher than that in normal tissue (cancer vs. normal: odds ratio (OR) =9.59, 95% confidence interval (CI): 5.97, 15.39, p<0.00001; borderline vs. normal: OR=4.13, 95% (CI): 2.43, 7.02, p<0.00001; cancer vs. borderline: OR=2.70, 95% (CI): 1.69, 4.31, p<0.0001). The expression of HIF-1α in III-IV stage or lymph node metastasis was significantly higher than that in I-II stage or that without lymph node metastasis, respectively (OR=2.66, 95% (CI): 1.87,3.79, p<0.00001; OR= 3.98, 95% (CI): 2.10,12.89, p<0.0001). HIF-1α was associated with histological grade of cancer (Grade 3 vs. Grade 1: OR=3.77, 95% (CI): 2.76,5.16, p<0.00001; Grade 3 vs. Grade 2: OR=1.62, 95% (CI): 1.20,2.19, p=0.002; Grade 2 vs. Grade 1: OR=2.34, 95% (CI): 1.82,3.00, p<0.00001),5-years disease free survival (DFS) rates (OR=2.93, 95% (CI):1.43,6.01, p=0.001) and 5-years overall survival (OS) rates (OR=5.53, 95% (CI): 2.48,12.31, p<0.0001).

CONCLUSION

HIF-1α is associated with the malignant degree, FIGO stage, histological grade, lymph node metastasis, 5-years survival rate and recurrence rate of gynecological cancer. It may play an important role in clinical treatment and prognostic evaluation.

Overexpression of hypoxia-inducible factor-1α is a predictor of poor prognosis in cervical cancer: a clinicopathologic study and a meta-analysis

BACKGROUND

Published data on the prognostic value of hypoxia-inducible factor-1α (HIF-1α) expression in cervical cancer are conflicting and heterogeneous. We aimed to derive a more precise estimation of them.

METHODS

We conducted a clinicopathologic study in 74 patients with early-stage cervical cancer treated through surgery and performed a meta-analysis among patients with cervical cancer of all stages to estimate the prognostic importance of HIF-1α expression for disease-free survival (DFS) and overall survival (OS). Expression of HIF-1α was evaluated through immunohistochemistry.

RESULTS

A positive nuclear expression of HIF-1α was found in 94.6% of all specimens. There were significant associations between HIF-1α expression and International Federation of Gynecology and Obstetrics stage (P = 0.024), tumor size (P = 0.003), and anemia (P = 0.010), respectively. Log-rank tests revealed significant correlations between HIF-1α expression, International Federation of Gynecology and Obstetrics stages, tumor grade, tumor size and DFS/OS, respectively. The multivariate Cox regression analyses revealed HIF-1α overexpression and high tumor grade to be independent predictors for impaired DFS (HIF-1α overexpression: hazard ratio [HR], 2.67; 95% confidence interval [CI], 1.10-6.47; high tumor grade: HR, 5.56; 95% CI, 1.47-21.13) and OS (HIF-1α overexpression: HR, 2.57; 95% CI, 1.06-6.23; high tumor grade: HR, 6.23; 95% CI, 1.49-25.97). The results of 10 studies indicated that HIF-1α overexpression predicted poor DFS (HR, 1.98; 95% CI, 1.22-3.21) and OS (HR, 2.58; 95% CI, 1.86-3.56) for cervical cancer.

CONCLUSIONS

The present clinicopathologic study and meta-analysis showed that HIF-1α overexpression is associated with poor survival of cervical cancer and emphasized the importance of HIF-1α as a predictor for cervical cancer.

Angiogenesis and antiangiogenic agents in cervical cancer

Standard treatment of cervical cancer (CC) consists of surgery in the early stages and of chemoradiation in locally advanced disease. Metastatic CC has a poor prognosis and is usually treated with palliative platinum-based chemotherapy. Current chemotherapeutic regimens are associated with significant adverse effects and only limited activity, making identification of active and tolerable novel targeted agents a high priority. Angiogenesis is a complex process that plays a crucial role in the development of many types of cancer. The dominant role of angiogenesis in CC seems to be directly related to human papillomavirus-related inhibition of p53 and stabilization of hypoxia-inducible factor-1α. Both of these mechanisms are able to increase expression of vascular endothelial growth factor (VEGF). Activation of VEGF promotes endothelial cell proliferation and migration, favoring formation of new blood vessels and increasing permeability of existing blood vessels. Since bevacizumab, a recombinant humanized monoclonal antibody binding to all isoforms of VEGF, has been demonstrated to significantly improve survival in gynecologic cancer, some recent clinical research has explored the possibility of using novel therapies directed toward inhibition of angiogenesis in CC too. Here we review the main results from studies concerning the use of antiangiogenic drugs that are being investigated for the treatment of CC.

The HIF-1α/CXCR4 pathway supports hypoxia-induced metastasis of human osteosarcoma cells

HIF-1α mediates hypoxia-induced expression of the chemokine receptor CXCR4 and contributes to metastasis in many different cancers. We have previously shown that hypoxia promotes migration of human osteosarcoma cells by activating the HIF-1α/CXCR4 pathway. Here, immunohistochemical analysis showed that unlike control osteochondroma samples, osteosarcoma specimens were characterized by elevated expression levels of HIF-1α and CXCR4. Moreover, we found that hypoxia-induced invasiveness was more pronounced in high metastatic potential F5M2 osteosarcoma cells than in low metastatic potential F4 cells, and that this induction was sensitive to treatment with the CXCR4 antagonist AMD3100 and the HIF-1α inhibitor KC7F2. Interestingly, hypoxia-induced CXCR4 expression persisted after cultured osteosarcoma cells were returned to normoxic conditions. These observations were confirmed by experiments in a mouse model of osteosarcoma lung metastasis showing that hypoxia stimulation of pulmonary metastasis was greater in F5M2 than in F4 cells, and was sensitive to treatment with AMD3100. Our study provides further evidence of the contributions of hypoxia and the HIF-1α/CXCR4 pathway to the progression of osteosarcoma, and suggests that this axis might be efficiently leveraged in the development of novel osteosarcoma therapeutics.

Synthesis and evaluation of (18)F-labeled tertiary benzenesulfonamides for imaging carbonic anhydrase IX expression in tumours with positron emission tomography

Three tertiary benzenesulfonamide inhibitors 4a-c were radiolabeled with (18)F and evaluated for imaging carbonic anhydrase IX (CA IX) expression with positron emission tomography. All three inhibitors exhibit <10 nM affinity for CA IX with no measurable affinity for CA II. Despite good affinity/selectivity to CA IX and excellent stability in plasma, uptake of [(18)F]4a-c in CA IX-expressing HT-29 tumours was low without significant contrast. [(18)F]4a,b were excreted rapidly, while [(18)F]4c exhibited significant in vivo defluorination leading to high bone uptake. Due to minimal uptake in HT-29 tumours compared to normal organs/tissues, (18)F-labeled benzenesulfonamides [(18)F]4a-c are not suitable as CA IX imaging agents.

Candidate biomarkers for cervical cancer treatment: Potential for clinical practice (Review)

Cervical cancer ranks high among the causes of female cancer mortalities and is an important disease in developing and developed countries. Current diagnosis of cervical cancer depends on colposcopy, pathological diagnosis and preoperative diagnosis using methods, including magnetic resonance imaging and computed tomography. Advanced cervical cancer has a poor prognosis. The tumor marker squamous cell carcinoma is conventionally used for screening, but recent studies have revealed the mechanisms of carcinogenesis and the factors associated with a poor prognosis in cervical cancer. These include epigenetic biomarkers, with the methylation level of the checkpoint with forkhead and ring finger gene being potentially useful for predicting the malignancy of cervical cancer and sensitivity to treatment with paclitaxel. The extent of methylation of the Werner DNA helicase gene is also useful for determining sensitivity to an anticancer agent, CPT-11. In addition to epigenetic changes, the expression levels of hypoxia-inducible factor 1α subunit, epidermal growth factor receptor and cyclooxygenase-2 have been reported as possible biomarkers in cervical cancer. Novel prognostic factors, including angiogenic factors, fragile histidine triad, thymidylate synthase, glucose-related protein 58 and mucin antigens, have also been described, and hemoglobin and platelets may also be significant prognostic biomarkers. Utilization of these biomarkers may facilitate personalized treatment and improved outcomes in cervical cancer.

Proline-hydroxylated hypoxia-inducible factor 1α (HIF-1α) upregulation in human tumours

The stabilisation of HIF-α is central to the transcriptional response of animals to hypoxia, regulating the expression of hundreds of genes including those involved in angiogenesis, metabolism and metastasis. HIF-α is degraded under normoxic conditions by proline hydroxylation, which allows for recognition and ubiquitination by the von-Hippel-Lindau (VHL) E3 ligase complex. The aim of our study was to investigate the posttranslational modification of HIF-1α in tumours, to assess whether there are additional mechanisms besides reduced hydroxylation leading to stability. To this end we optimised antibodies against the proline-hydroxylated forms of HIF-1α for use in formalin fixed paraffin embedded (FFPE) immunohistochemistry to assess effects in tumour cells in vivo. We found that HIF-1α proline-hydroxylated at both VHL binding sites (Pro402 and Pro564), was present in hypoxic regions of a wide range of tumours, tumour xenografts and in moderately hypoxic cells in vitro. Staining for hydroxylated HIF-1α can identify a subset of breast cancer patients with poorer prognosis and may be a better marker than total HIF-1α levels. The expression of unhydroxylated HIF-1α positively correlates with VHL in breast cancer suggesting that VHL may be rate-limiting for HIF degradation. Our conclusions are that the degradation of proline-hydroxylated HIF-1α may be rate-limited in tumours and therefore provides new insights into mechanisms of HIF upregulation. Persistence of proline-hydroxylated HIF-1α in perinecrotic areas suggests there is adequate oxygen to support prolyl hydroxylase domain (PHD) activity and proline-hydroxylated HIF-1α may be the predominant form associated with the poorer prognosis that higher levels of HIF-1α confer.

Primary tumor vascularity, HIF-1α and VEGF expression in vulvar squamous cell carcinomas: their relationships with clinicopathological characteristics and prognostic impact

BACKGROUND

Increased vascularity is a crucial event in the tumor progression and has prognostic significance in various cancers. However, the ultimate role of angiogenesis in the pathogenesis and clinical outcome of vulvar carcinoma patients is still not settled.

METHODS

Tumor vascularity using CD34 stained slides measured by Chalkley counting method as well as hypoxia-inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF) immunoexpression was examined in 158 vulvar squamous cell carcinomas. Associations between vascular Chalkley count, HIF-1α and VEGF expression and clinicopathological factors and clinical outcome were evaluated.

RESULTS

High CD34 Chalkley count was found to correlate with larger tumor diameter (P = 0.002), deep invasion (P < 0.001) and HIF-1α (P = 0.04), whereas high VEGF expression correlate significantly with poor tumor differentiation (P = 0.007). No significant association between CD34 Chalkley counts and VEGF expression and disease-specific survival was observed. High HIF-1α expression showed better disease specific survival in both univariate and multivariate analyses (P = 0.001).

CONCLUSIONS

A significant association between high tumor vascularity and larger tumor size as well as deeper tumor invasion suggests an important role of angiogenesis in the growth and progression of vulvar carcinomas. HIF-1α expression in vulvar carcinomas was a statistically independent prognostic factor.

Prognostic assessment of hypoxia and metabolic markers in cervical cancer using automated digital image analysis of immunohistochemistry

BACKGROUND

Hypoxia inducible factor-1 alpha (HIF-1α), induced by tumor hypoxia, regulates tumor cell metabolism and metastasis by up-regulation of c-Met, carbonic anhydrase 9 (CA9) and glucose transporter 1 (GLUT1). The prognostic significance of hypoxia and metabolic markers is not clearly defined in cervical cancer. Here, we have examined the primary players in the hypoxia signaling pathway, by immunohistochemistry, but confirming their interactions, as well as defining which proteins are associated with outcome.

METHODS

The study subjects were comprised of cervical intraepithelial neoplasia (CIN, n = 209), carcinoma in situ (CIS, n = 74), cervical cancer (n = 179), and matched nonadjacent normal tissues (n = 357). Immunohistochemistry (IHC) was performed to identify HIF-1α, c-Met, CA9, and GLUT1. IHC scoring was performed using automated digital image analysis and the association of hypoxic markers with prognostic outcome was evaluated.

RESULTS

HIF-1α, c-Met, CA9 and GLUT1 expression were higher in cervical cancer than in CIN and normal cervix (all P < 0.001). Among these markers, expression of HIF-1α and c-Met were significantly different in FIGO stage (P < 0.001 and P = 0.019, respectively) and patients with lymph node metastasis (P < 0.001 and P = 0.010, respectively). HIF-1α expression was correlated with c-Met expression in cervical cancer (P < 0.001). High expression of HIF-1α and c-Met showed worse 5-year overall survival rate (P = 0.047 and P = 0.005, respectively) than low expression group, but CA9 and GLUT1 did not show significant survival difference. After adjusting the prognostic covariates, c-Met was found to be an independent risk factor (HR=3.27; 95% CI, 1.05-10.23, P = 0.041) for overall survival in cervical cancer.

CONCLUSIONS

We demonstrate that c-Met correlates with HIF-1α and is a poor prognostic factor in survival in cervical cancer.

Insights towards sulfonamide drug specificity in α-carbonic anhydrases

Carbonic anhydrases (CAs, EC 4.2.1.1) are a group of metalloenzymes that play important roles in carbon metabolism, pH regulation, CO2 fixation in plants, ion transport etc., and are found in all eukaryotic and many microbial organisms. This family of enzymes catalyzes the interconversion of CO2 and HCO3(-). There are at least 16 different CA isoforms in the alpha structural class (α-CAs) that have been isolated in higher vertebrates, with CA isoform II (CA II) being ubiquitously abundant in all human cell types. CA inhibition has been exploited clinically for decades for various classes of diuretics and anti-glaucoma treatment. The characterization of the overexpression of CA isoform IX (CA IX) in certain tumors has raised interest in CA IX as a diagnostic marker and drug target for aggressive cancers and therefore the development of CA IX specific inhibitors. An important goal in the field of CA is to identify, rationalize, and design potential compounds that will preferentially inhibit CA IX over all other isoforms of CA. The variations in the active sites between isoforms of CA are subtle and this causes non-specific CA inhibition which leads to various side effects. In the case of CA IX inhibition, CA II along with other isoforms of CA provide off-target binding sites which is undesirable for cancer treatment. The focus of this article is on CA IX inhibition and two different structural approaches to CA isoform specific drug designing: tail approach and fragment addition approach.

Prospective technical validation and assessment of intra-tumour heterogeneity of a low density array hypoxia gene profile in head and neck squamous cell carcinoma

BACKGROUND AND PURPOSE

Tumour hypoxia is associated with a poor prognosis in head and neck squamous cell carcinoma (HNSCC), however there is no accepted method for assessing hypoxia clinically. We aimed to conduct a technical validation of a hypoxia gene expression signature using the TaqMan Low Density Array (TLDA) platform to investigate if this approach reliably identified hypoxic tumours.

MATERIALS AND METHODS

Tumour samples (n=201) from 80 HNSCC patients were collected prospectively from two centres. Fifty-three patients received pimonidazole prior to surgery. TaqMan Low Density Array-Hypoxia Scores (TLDA-HS) were obtained by quantitative real-time PCR (qPCR) using a 25-gene signature and customised TLDA cards. Assay performance was assessed as coefficient of variation (CoV).

RESULTS

The assay was sensitive with linear reaction efficiencies across a 4 log(10) range of inputted cDNA (0.001-10 ng/μl). Intra- (CoV=6.9%) and inter- (CoV=2.0%) assay reproducibility were excellent. Intra-tumour heterogeneity was lower for TLDA-HS (23.2%) than for pimonidazole (67.2%) or single gene measurements of CA9 (62.2%), VEGFA (45.0%) or HIG2 (39.4%). TLDA-HS in HNSCC cell lines increased with decreasing pO(2). TLDA-HS correlated with Affymetrix U133 Plus 2.0 microarray HS (p<0.01) and positive pimonidazole scores (p=0.005).

CONCLUSIONS

Gene expression measurements of hypoxia using a 25-gene signature and TLDA cards are sensitive, reproducible and associated with lower intra-tumour heterogeneity than assaying individual genes or pimonidazole binding. The approach is suitable for further assessment of prognostic and predictive capability in clinical trial material.

Measurements of hypoxia ([(18)F]-FMISO, [(18)F]-EF5) with positron emission tomography (PET) and perfusion using PET ([(15)O]-H(2)O) and power Doppler ultrasonography in feline fibrosarcomas*

Abstract The aim of this study was to evaluate if hypoxia in feline fibrosarcomas can be detected. This was done using positron emission tomography (PET), two hypoxia tracers and polarographic pO(2) measurements. Of the seven cats included, five received [(18)F]-fluoromisonidazole and two 2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl) acetamide. Perfusion was evaluated with [(15)O]-H(2)O (n = 4) and with contrast-enhanced power Doppler ultrasonography (n = 5). Hypoxia was detected in three cats. Polarographic pO(2) measurements did not confirm PET results. In the ultrasonographic evaluation, low vascularity and low perfusion were seen with a peripheral vascular pattern and no perfusion in the centre of the tumour. This was in contrast to the [(15)O]-H(2)O scans, where central perfusion of the tumour was also found. In conclusion, it appears that hypoxia exists in this tumour type. The presence of tumour necrosis and heterogeneous hypoxia patterns in these tumours may explain the found discrepancies between the applied techniques.