Immunohistochemical diagnosis of methylthioadenosine phosphorylase (MTAP) deficiency in non-small cell lung carcinoma

Methylthioadenosine phosphorylase (MTAP) is involved in the metabolism of purines and converts methylthioadenosine (MTA) to adenine. It is abundant in all normal tissues but is deficient in various tumors. Here, we investigated MTAP deficiency in clinical samples of lung cancer using immunohistochemistry (IHC), and compared these results with those obtained by real-time PCR. Seventy-five samples were obtained from patients who underwent operations for non-small cell lung cancer (NSCLC). MTAP genetic analysis, using real-time PCR, and IHC were carried out on the samples. Methylation-specific primers were used to analyze methylation of the MTAP promoter, using DNA treated with sodium bisulfite. Sixty-nine of 75 samples were compared using both IHC and real-time PCR. The IHC results were consistent with those of real-time PCR in 56 samples. Of 62 positive samples tested by real-time PCR, only 49 (79%) were MTAP-positive by IHC. Seven samples were MTAP-negative by real-time PCR and IHC. In 13 samples of PCR (+) and IHC (-), six samples showed that the promoter region of MTAP was methylated. IHC is an accurate and useful diagnostic method for detecting MTAP deficiency in NSCLC, and the frequency of MTAP deficiency was found to be relatively high. The metabolic alterations diagnosed by IHC could be exploited for selective chemotherapy.     

Surgery promotes implantation of disseminated tumor cells, but does not increase growth of tumor cell clusters

INTRODUCTION: Local recurrence and peritoneal dissemination is common after intentionally curative resection of colorectal carcinoma. It is not yet clear which mechanisms stimulate post-operative intra-abdominal tumor development. Enhanced adhesion or growth of tumor cells and/or post-operative immuno suppression may influence tumor recurrence. AIMS OF THE STUDY: In the present study, we evaluated effects of local and remote surgery on intra-abdominal tumor development. MATERIALS AND METHODS: A standardized intra-abdominal trauma was inflicted by rubbing both uterus horns in laparotomy groups, while a dorsolateral thoracotomy was performed in thoracotomy groups (on day -1, 0, or +3). To induce tumor development rats were injected intra-peritoneally with the coloncarcinoma cell line CC531s on day 0 and evaluated after 21 days. RESULTS: Rats undergoing laparotomy and injection on day 0 showed significantly higher tumorload than control rats (195 +/- 20 vs. 47 +/- 29, P < 0.001). When a laparotomy was performed, the day before tumor inoculation even higher tumorload was seen (245 +/- 37 vs. 195 +/- 20, P < 0.01). Strikingly, performing a thoracotomy on the day before or on the same day as tumor inoculation resulted in enhanced tumorload compared to controls as well (135 +/- 84 vs. 47 +/- 29; P < 0.001 and 88 +/- 38 vs. 47 +/- 29; P < 0.02, respectively). Either laparotomy or thoracotomy 3 days after tumor cell inoculation did not affect growth of pre-existing tumor cell clusters. CONCLUSIONS: The (post) surgical intra-peritoneal microenvironment enhances successful implantation of spilled tumor cells, whereas growth of adhered tumor cell clusters is not affected. The inflammatory response as a result of remote surgery promotes successful tumor development as well.     

Non-anti-coagulant heparin inhibits metastasis but not primary tumor growth

Experimental and clinical studies indicate that low molecular weight heparins (LMWH) may inhibit cancer and/or metastasis. The purpose of this study was to investigate whether it is possible to design non-anti-coagulant, anti-metastatic compounds based on heparin. The LMWH Tinzaparin and a series of non-anti-coagulant (NAC) heparin derivatives, varying in size from 2,500 to 10,000 Da, were tested for their anti-metastatic activity in an experimental B16F10 metastasis model. The most promising NAC heparin drug candidate and Tinzaparin were further evaluated in B16F10 model with spontaneous metastasis from a primary subcutaneous tumor. In the experimental model, Tinzaparin, NAC2500, and NAC6000 were inactive whereas both NAC8000 and NAC10000 significantly inhibited the number of induced experimental metastases by 69 and 73%, respectively. NAC8000 was chosen over NAC10000 for further studies because of its lower molecular weight with an expected better bioavailability. In the spontaneous model, Tinzaparin had no inhibitory effect on metastatic activity. In contrast, NAC8000 significantly inhibited the number of metastases by 58%. Neither Tinzaparin nor NAC8000 inhibited primary subcutaneous tumor growth. Together, these results indicate that the anti-metastatic effect of heparin derivatives is not a result of anti-coagulant activity. The non-anti-coagulant NAC8000 specifically inhibits early establishment of tumor cells, but not primary tumor growth. Therefore, NAC8000 is a promising non-anti-coagulant compound for preventing tumor metastasis.     

KRAS mutations are associated with inferior clinical outcome in patients with metastatic colorectal cancer,but are not predictive for benefit with cediranib

PurposeThe prognostic potential of KRAS mutations in advanced colorectal cancer (CRC) patients and the impact of KRAS mutation status on the effectiveness of chemotherapy or vascular endothelial growth factor (VEGF) signalling inhibitor therapy remain unclear. KRAS mutation status was evaluated retrospectively as a potential prognostic/predictive marker of clinical outcomes using tumour samples from patients with metastatic CRC receiving cediranib or placebo plus FOLFOX/XELOX in a Phase III trial (HORIZON II; NCT00399035).MethodsKRAS codon 12 and 13 mutation analyses were performed using a commercially available, allele-specific, amplification refractory mutation system (ARMS)-based polymerase chain reaction (PCR) assay. Retrospective analyses of progression-free survival (PFS) and overall survival (OS) according to KRAS mutation status were performed for patients randomised to cediranib 20 mg or placebo.ResultsKRAS status was determined in 599/1076 patients (cediranib 20 mg, n = 285/502; cediranib 30 mg, n = 110/216; placebo, n = 204/358). Baseline characteristics were similar across KRAS mutant (n = 258; 24.0%), wild-type (n = 341; 31.7%) and status unknown (n = 477; 44.3%) groups. There was a trend towards improved PFS and OS in the wild-type versus mutant subgroups independent of treatment (cediranib 20 mg and placebo: PFS hazard ratio (HR) = 0.85 [median PFS: wild-type = 8.5 months; mutant = 8.3 months]; OS HR = 0.71 [median OS: wild-type = 20.9 months; mutant = 16.9 months]). Treatment effects were similar between KRAS subgroups for cediranib 20 mg versus placebo (PFS: wild-type HR = 0.78, mutant HR = 0.82; OS: wild-type HR = 0.92, mutant HR = 1.01).ConclusionData from this large randomised Phase III study show that KRAS codon 12/13 mutations have negative prognostic value in metastatic CRC patients receiving treatment with FOLFOX/XELOX, but KRAS mutation status is not predictive of treatment benefit with cediranib, using PFS or OS.     

Thymidine phosphorylase activity required for tumor angiogenesis and growth

Thymidine phosphorylase (TP) is identical to platelet-derived endothelial cell growth factor (PD-ECGF), and has angiogenic activity. We examined the involvement of TP activity in tumor growth and angiogenesis. KB cells were transfected with wild-type or mutant (L148R) PD-ECGF cDNA, and two sublines with high TP activity, KB/wt4 and KB/wt6, and one subline with no TP activity, KB/L148R, were cloned, respectively. The doubling times of these subclones in vitro were similar to that of KB cells. However, the growth of KB/wt4 and KB/wt6 cells was significantly faster when xenografted into nude mice than that of control cells with no TP activity. The tumors with high TP activity (KB/wt4 and KB/wt6) had significantly more microvessels than those with no TP activity (KB/-, KB/CV and KB/L148R) (P<0.01). These results, taken together with previous reports, suggest that the TP enzyme activity itself is involved in angiogenesis and growth of the KB tumors.     

'Classical' but not 'other' mutations of EGFR kinase domain are associated with clinical outcome in gefitinib-treated patients with non-small cell lung cancer

'Classical' mutations in the EGFR tyrosine kinase domain (exons 18, 19 and 21) have been associated with sensitivity to tyrosine kinase inhibitors (TKIs) in patients with NSCLC. The aim of the current study was to evaluate whether other than the classical G719X, DEL19 and L858R mutations of EGFR confer sensitivity to TKIs. Genomic DNA was extracted from microdissected formalin-fixed paraffin-embedded tumour tissue from 86 patients treated with gefitinib. Exons 18, 19 and 21 were amplified and subjected to direct sequencing. Eleven (13%) patients harboured the classical exon's 18, 19 and 21 mutations, while 14 (16%) had 'other' variants. There was a significantly higher percentage of 'never-smoker' patients with 'classical' EGFR mutations (P=0.002). Among patients with 'classical' mutations 3 patients achieved PR and 7 SD, while in the 'other' mutations group 10 patients had SD as best response. In the wild-type group, there were 3 patients with PR and 25 with SD. Median TTP was 16, 64 (P=0.002) and 21 weeks and median survival was 36, 78 and 67 weeks for patients with wild-type, 'classical' and 'other' EGFR mutations, respectively. The clinical relevance of 'other' EGFR mutation variants remains uncertain and requires further assessment in a prospective study.     

L1 augments cell migration and tumor growth but not beta3 integrin expression in ovarian carcinomas

L1 is a neural cell adhesion molecule involved in cell migration, axon growth and guidance. Recent data have shown that L1 is overexpressed in ovarian and endometrial tumors and is associated with bad prognosis. How L1 promotes tumor progression is presently unknown. Here we show that L1 expression is predominantly confined to the invasive front of ovarian carcinomas. Overexpression of L1 in carcinoma cell lines by adenovirus-mediated gene transfer enhanced the haptotactic cell migration on extracellular matrix proteins. Expression of L1 augmented tumor growth of carcinomas xenografted in nonobese diabetic/severe combined immunodeficient mice (NOD/SCID). A recent report has demonstrated L1-dependent upregulation of beta3 integrin involving activation of the extracellular signal-regulated kinase (erk) pathway. We find that L1 and beta3 integrin are not coexpressed in ovarian carcinoma tissues. Overexpression of L1 did not upregulate beta3 integrin in ovarian carcinoma cell lines but could do so in HEK293 cells. Our results suggest that L1 could drive progression by enhancing cell migration and tumor growth but that L1 dependent and erk-regulated gene expression requires cell-type specific elements.     

Tumor necrosis factor-alpha, but not lymphotoxin, stimulates growth of tumor cells in hairy cell leukemia

We investigated the effect of recombinant tumor necrosis factor-alpha (rTNF-alpha) and recombinant lymphotoxin (rLT) in the growth modulation of purified hairy cell leukemia (HCL) cells. In response to rTNF-alpha, HCL cells from five of eight patients showed a 3 to 23-fold thymidine incorporation above their unstimulated controls. The effect was time and dose dependent with a maximum between 10 and 25 ng/ml rTNF-alpha after 120-hr incubation. rLT (1-50 ng/ml), however, could not enhance DNA synthesis in six of six cases. Cell number of rTNF-alpha stimulated cells ranged from 2-3 x 10(6)/ml from days 0-50 whereas cell number of unstimulated controls decreased from 3 x 10(6)/ml at day 0 to 0.01-0.02 x 10(6)/ml after 50 days in culture. rTNF-alpha induced proliferation could be suppressed in all HCL cell populations by 0.3 ng/ml recombinant interferon alpha (100 U/ml rIFN-alpha). TNF binding studies in two patients revealed that both TNF-sensitive HCL cells (1,990 +/- 148 receptors/cell) as well as TNF-insensitive HCL cells (1,261 +/- 101 receptors/cell) express specific receptors for TNF-alpha. These data show that rTNF-alpha and rLT have different effects on the growth of HCL cells. In addition there is a subgroup of patients who show no response to rLT or rTNF-alpha.     

Chemotherapy targeting methylthioadenosine phosphorylase (MTAP) deficiency in adult T cell leukemia (ATL).

Methylthioadenosine phosphorylase (MTAP) is an important enzyme used for the salvage of adenine and methionine. Cells lacking this enzyme are expected to be sensitive to purine synthesis inhibitors and/or methionine starvation. We reported previously that the MTAP gene is deleted in adult T cell leukemia (ATL) cells. In the present study, we expanded our series and used a real-time quantitative PCR assay for accurate diagnosis of the deletion and nine of 65 primary ATL samples (13.8%) were MTAP negative. In spite of this low incidence, ATL cells showed significantly higher sensitivity to L-alanosine, an inhibitor of de novo adenosine monophosphate (AMP) synthesis, than normal lymphocytes, suggesting that the MTAP gene is inactivated not only by deletion but also by other mechanisms. Indeed, a real-time quantitative RT-PCR assay disclosed that primary ATL cells had significantly lower MTAP mRNA expression than normal lymphocytes. Since MTAP-negative ATL cell lines also showed much higher sensitivity to L-alanosine than MTAP-positive ATL cell lines, we used these cell lines to investigate whether it is possible to develop selective therapy targeting MTAP deficiency. A substrate of MTAP, methylthioadenosine (MTA) or its substitutes rescued concanavalin A (Con A)-activated normal lymphocyte proliferation from L-alanosine toxicity. All the compounds except 5'-deoxyadenosine, however, also caused the undesirable rescue of MTAP-negative ATL cell lines. 5'-Deoxyadenosine had the desired ability to rescue hematopoietic progenitor cells without rescuing ATL cell lines. These results support the rationale for a chemotherapy regimen of L-alanosine combined with 5'-deoxyadenosine rescue in MTAP-deficient ATL.     

Increased thymidylate synthase protein levels are principally associated with proliferation but not cell cycle phase in asynchronous human cancer cells.

We have analysed cell cycle variations in thymidylate synthase (TS) protein in asynchronously growing NCl H630 and HT 29 colon cancer and MCF-7 breast cancer cell lines. Western immunoblot analysis using the TS 106 monoclonal antibody revealed a 14- to 24-fold variation in TS levels between the peak exponential and confluent growth phase in the three cell lines. Similar variations in TS levels and TS activity were detected using the 5-fluorodeoxyuridine monophosphate and deoxyuridine monophosphate biochemical assays. The percentage of cells in S-phase, which paralleled changes in TS levels, reached a maximum of 38-60% in asynchronous exponentially growing cells compared with 5-10% in confluent cells. In asynchronous exponential cells, analysis of TS levels in each cell cycle phase using two-parameter flow cytometric analysis revealed that TS protein levels were 1.3- to 1.5-fold higher in S than in G0/G1 phase cells, and 1.5- to 1.8-fold higher in G2/M than G0/G1 cells. Similar differences of 1.1- to 1.5-fold between G0/G1 and S-phase and 1.6- to 1.9-fold between G0/G1 and G2/M-phase were detected by Western immunoblot and biochemical assays. TS protein was not detectable by Western blot analysis, flow cytometry or biochemical analysis in the G0/G1 population of confluent cells. Twenty-six per cent of cells in this population were G0 cells compared with 2% in exponentially growing cells. In contrast to TS, a 4-fold difference in thymidine kinase (TK) was detected between G0/G1 and S-phase cells in exponentially growing MCF-7 cells. The level of TS enzyme is associated with cellular proliferation and the percentage of cells in S-phase; however, TS protein is not exclusively associated with S-phase in asynchronously growing cells. The variation in TS levels between exponentially growing and confluent cell population appears to be due to differences in TS levels between G0 and G1 cells.     

Biomarkers of inflammation are associated with colorectal cancer risk in women but are not suitable as early detection markers

Initial studies have investigated the association between inflammation and colorectal cancer (CRC) using C‐reactive protein (CRP) as a proinflammatory biomarker and have noted inconsistent results among women. We here report the findings from a large prospective study with repeat measurements of CRP, as well as serum amyloid A (SAA), an additional biomarker of inflammation, and risk of CRC. In the Women's Health Initiative Observational Study, we examined associations of CRP and SAA with CRC using repeat assessments (baseline and 3‐year follow‐up) among 953 matched case–control pairs for CRP and 966 pairs for SAA. Multivariate‐adjusted conditional‐logistic regression models were used with two‐sided tests of significance. Receiver operating characteristic (ROC) curve analysis assessed their utility as early detection markers. Colon cancer risk (odds ratio [OR] and 95% confidence intervals) among women in the highest quintiles of CRP or SAA compared to those in the lowest quintiles was OR_colon/CRP = 1.37 (0.95–1.97, p‐trend = 0.04) and OR_colon/SAA = 1.26 (0.88–1.80, p‐trend = 0.10), respectively. Women with elevated concentrations of both CRP and SAA had an increased risk of OR_colon = 1.50 (1.12–2.00, p‐value = 0.006) compared to those with low concentrations. No positive associations were observed with rectal cancer and weaker associations for CRC overall. Temporal changes in biomarkers more than 3 years did not predict risk. The area under the 6‐month ROC curve for CRP+SAA was 0.62 (95% confidence interval = 0.55–0.68). Elevated inflammatory biomarkers are associated with an increased risk of CRC, mainly colon cancer. Nevertheless, changes in the biomarkers over time do not suggest that they merit consideration as early detection markers for CRC.     

Thymidine phosphorylase/platelet-derived endothelial cell growth factor expression associated with hepatic metastasis in gastric carcinoma.

It is known that angiogenesis plays an important role in the growth and metastasis of solid tumours. Several angiogenic factors have been identified and platelet-derived endothelial cell growth factor (PD-ECGF) is thought to be one such factor. Recently, it was reported that thymidine phosphorylase (dThdPase) is identical to PD-ECGF. Using immunohistochemical staining with an anti-dThdPase antibody, we investigated the correlation between dThdPase expression and the microvessel density in 120 gastric carcinomas. The microvessel density, determined by immunostaining for factor VIII-related antigen, was significantly higher in dThdPase-positive tumours than in dThdPase-negative tumors. There was a significant correlation between dThdPase expression and the increment of microvessel density. Moreover, regarding distant organ metastasis, the frequency of hepatic metastasis was significantly higher (P < 0.01) in patients with dThdPase-positive tumours than in those with dThdPase-negative tumors. In summary, it was suggested that dThdPase expression is closely associated with the promotion of angiogenesis and hepatic metastasis in gastric carcinoma.     

Apoptotic circulating tumor cells (CTCs) in the peripheral blood of metastatic colorectal cancer patients are associated with liver metastasis but not CTCs

Enumeration of circulating tumor cells (CTCs) by the CellSearch system provides prognostic information in metastatic colorectal cancer, regardless of metastatic site. We found that CTCs generally represent <1% of observed events with CellSearch analysis and adapted scoring criteria to classify other peripheral blood events. Examination of twenty two metastatic colorectal cancer patients'' blood revealed that patients with high CEA or liver metastases, but not lung or distant lymph node metastases, possessed significant numbers of apoptotic CTCs prior to treatment initiation by Fischer''s exact test. Six out of eleven patients with liver metastasis possessed apoptotic CTCs whereas one of nine patients with other metastases had measurable apoptotic CTCs. An elevated CTC number was not necessarily associated with apoptotic CTCs or CTC debris by Spearman''s correlation, suggesting the metastatic site rather than CTCs per se as contributing to the origin of these events.     

Thymidylate synthase gene promoter polymorphisms are associated with TSmRNA expressions but not with microsatellite instability in colorectal cancer

BACKGROUND: Microsatellite instability (MSI) is a biological characteristic of most tumours, being involved in 85% of hereditary non-polyposis colorectal cancer (HNPCC). It also occurs in 10-15% of sporadic colorectal cancers (CRC). HNPCC appears to be caused by germline mutations in mismatch repair (MMR) genes, which are responsible for repairing single base-pair mismatches. MSI is also associated with a better response of CRC to adjuvant chemotherapy with fluoropyrimidines. We investigated any relationship between the MSI status and the TSmRNA expression, the polymorphisms of 5-Fluorouracil (5-FU cellular target, the enzyme thymidylate synthase (TS) and TS expression evaluated by means of immunohistochemistry. MATERIALS AND METHODS: A series of 80 colorectal cancers was evaluated for MSI and polymorphisms in the 3'UTR and the 5'UTR of the TS gene by a PCR assay. TSmRNA was quantified by real-time PCR and the TS expression by immunohistochemical assay. RESULTS: There was no significant association between the polymorphisms in the TS gene and the MSI or between the TSmRNA expression and the MSI status. CRC with a 3R/3R or 2R/3R genotype showed a significantly higher TSmRNA expression than those with the 2R/2R genotype (p = 0.001 and p = 0.028, respectively). Another significant association was found between the TSmRNA expression and the TS immunohistochemical determination (p = < 0.05). No association was found between the polymorphism of the 3'UTR and the TSmRNA expression. CONCLUSION: Our data show that there is no association between MSI status and the polymorphisms in the 3' and 5' UTRs and the TS expression. Tumour samples displaying the 3R/3R or 2R/3R genotype of TS have higher TSmRNA levels than the 2R/2R genotype. Polymorphic variant of the 3'UTR does not influence the TSmRNA level. We found a relationship between the TSmRNA expression, evaluated by real-time PCR, and with the TS level determined by immunohistochemical assay. Thus, genotyping of the 5'UTR and quantification of the TSmRNA expression in human CRC could be considered as predictors for response to SFU-based chemotherapy. The evaluation of the TS expression by means of immunohistochemistry assay remains a safe and reliable assay in CRC.     

Preexisting lymphatic endothelium but not endothelial progenitor cells are essential for tumor lymphangiogenesis and lymphatic metastasis

Endothelial progenitor cells have been shown to contribute to angiogenesis in various tumor models. Here, we have studied the relative contributions of bone marrow (BM)-derived endothelial progenitors and pre-existing lymphatic vessels to tumor lymphangiogenesis. We did not find significant incorporation of genetically marked BM-derived cells in lymphatic vessels during tumor- or vascular endothelial growth factor C-induced lymphangiogenesis. The degree of tumor lymphangiogenesis correlated with lymphatic vessel density in the peritumoral area, and despite tumor lymphangiogenesis, lymphatic metastasis failed to occur in gene-targeted vascular endothelial growth factor C(+/-) mice that have hypoplasia of the lymphatic network. Our data demonstrate that during tumor lymphangiogenesis and cancer cell dissemination via the lymphatics, the newly formed lymphatic vessels sprout from the pre-existing local lymphatic network with little if any incorporation of BM-derived endothelial progenitor cells.     

B-raf exon 15 mutations are common in primary melanoma resection specimens but not associated with clinical outcome

Downstream of Ras, the serine/threonine kinase B-raf has recently been reported to be mutated, among other carcinomas, in a majority of melanoma cell lines with a preponderance of mutations within the kinase domain including the activating V599E transition. We therefore investigated a representative number of 50 primary melanoma resection specimens for the presence of mutations within the activation segment (exon 15) of the B-raf kinase domain. Applying polymerase chain reaction and single-strand conformation polymorphism gel electrophoresis, followed by DNA cloning and sequencing, we found 19 cases (38%) to harbor somatic B-raf exon 15 mutations. With respect to the B-raf protein sequence, the V599E mutation was predicted in 63% of these positive melanomas, followed in frequency by the V599K transition (31%). Detection of B-raf exon 15 mutations or prediction of the activating mutation V599E were not statistically associated with the risk for subsequent metastasis in the follow-up of patients. Altogether, the B-raf oncogene is affected in a substantial subset of melanoma resection specimens. As B-raf alterations possibly affect melanocyte-specific pathways controlling proliferation and differentiation, activation of this oncogene may contribute to the development of melanoma.     

Lymphotoxin amplification of tumor growth inhibition is specific for natural killer cells but not for macrophages

Lymphotoxin augments the susceptibility of tumorigenic guinea-pig cells to natural killer (NK) cell cytolysis in vitro but does not directly stimulate either NK cell or macrophage cytolytic action. The question whether lymphotoxin enhances the susceptibility of tumorigenic guinea-pig cells to cytolysis or other means of growth inhibition in vivo by syngeneic NK cells or macrophages was, therefore, examined using a modified tumor cell neutralization (Winn) assay. Mineral oil-, thioglycollate- or casein-induced peritoneal leukocytes, but not the macrophages isolated from the elicited leukocytes obtained from nonimmunized strain 2/N guinea-pigs, effected enhanced cytolysis of lymphotoxin-treated guinea-pig benzo (a)pyrene-induced 104CI tumor cells in vitro. Neither guinea-pig splenic NK cells nor oil-induced peritoneal macrophages alone inhibited the growth of 104CI cells as tumors in vivo when admixed with 104CI cells and injected into guinea-pigs. However, when the 104CI cells were treated with lymphotoxin before addition of effector cells, NK cells but not macrophages significantly reduced tumor growth in vivo. Therefore, the ability of lymphotoxin to increase the sensitivity of tumor cells to destruction mediated by natural leukocytes is specific for NK cells as compared to macrophages. This form of lymphokine amplification of natural leukocyte cytotoxicity may be one mechanism by which natural and acquired immunity serves or fails to prevent cancer and should be an important consideration in therapeutic approaches to eradicate or control tumor growth.     

The polymorphisms in the VHL and HIF1A genes are associated with the prognosis but not the development of renal cell carcinoma

BackgroundThe von Hippel–Lindau (VHL) tumor suppressor gene and hypoxia-inducible factor-1α (HIF1A) play a pivotal role in renal carcinogenesis. This study was aimed to clarify the influence of VHL and HIF1A polymorphisms on renal cell cancer (RCC) susceptibility and survival.Subjects and methodsWe genotyped four potentially functional single-nucleotide polymorphisms (rs779805 in VHL and rs11549465, rs11549467, and rs2057482 in HIF1A) and assessed their associations with RCC risk, clinicopathologic parameters in a case–control study of 620 patients and 623 controls, and the prognosis of RCC in a cohort of 311 patients.ResultsNo significant differences in VHL or HIF1A genotypes were observed between RCC cases and controls. However, individuals with ≥2 variant alleles of the four polymorphisms were associated with less frequent lymph node metastasis and lower clinical stage (P = 0.032 and P = 0.041, respectively). And the number of variant alleles was associated with improved survival in a dose–response manner (P_trend = 0.013). Furthermore, multivariate Cox regression analysis showed that the number of variant alleles (≥1 versus 0) was an independent prognostic factor for RCC survival (P = 0.036) together with clinical stage and tumor grade.ConclusionThe VHL and HIF1A polymorphisms may not influence RCC susceptibility but may jointly influence RCC progression and survival.