HIF Induces Human Embryonic Stem Cell Markers in Cancer Cells

<div>Abstract<p>Low oxygen levels have been shown to promote self-renewal in many stem cells. In tumors, hypoxia is associated with aggressive disease course and poor clinical outcomes. Furthermore, many aggressive tumors have been shown to display gene expression signatures characteristic of human embryonic stem cells (hESC). We now tested whether hypoxia might be responsible for the hESC signature observed in aggressive tumors. We show that hypoxia, through hypoxia-inducible factor (HIF), can induce an hESC-like transcriptional program, including the induced pluripotent stem cell (iPSC) inducers, <i>OCT4, NANOG, SOX2, KLF4, cMYC</i>, and <i>microRNA-302</i> in 11 cancer cell lines (from prostate, brain, kidney, cervix, lung, colon, liver, and breast tumors). Furthermore, nondegradable forms of HIFα, combined with the traditional iPSC inducers, are highly efficient in generating A549 iPSC-like colonies that have high tumorigenic capacity. To test potential correlation between iPSC inducers and HIF expression in primary tumors, we analyzed primary prostate tumors and found a significant correlation between NANOG-, OCT4-, and HIF1α-positive regions. Furthermore, NANOG and OCT4 expressions positively correlated with increased prostate tumor Gleason score. In primary glioma-derived CD133 negative cells, hypoxia was able to induce neurospheres and hESC markers. Together, these findings suggest that HIF targets may act as key inducers of a dynamic state of stemness in pathologic conditions. <i>Cancer Res; 71(13); 4640–52. ©2011 AACR</i>.</p></div>

<div>Abstract<p>Low oxygen levels have been shown to promote self-renewal in many stem cells. In tumors, hypoxia is associated with aggressive disease course and poor clinical outcomes. Furthermore, many aggressive tumors have been shown to display gene expression signatures characteristic of human embryonic stem cells (hESC). We now tested whether hypoxia might be responsible for the hESC signature observed in aggressive tumors. We show that hypoxia, through hypoxia-inducible factor (HIF), can induce an hESC-like transcriptional program, including the induced pluripotent stem cell (iPSC) inducers, <i>OCT4, NANOG, SOX2, KLF4, cMYC</i>, and <i>microRNA-302</i> in 11 cancer cell lines (from prostate, brain, kidney, cervix, lung, colon, liver, and breast tumors). Furthermore, nondegradable forms of HIFα, combined with the traditional iPSC inducers, are highly efficient in generating A549 iPSC-like colonies that have high tumorigenic capacity. To test potential correlation between iPSC inducers and HIF expression in primary tumors, we analyzed primary prostate tumors and found a significant correlation between NANOG-, OCT4-, and HIF1α-positive regions. Furthermore, NANOG and OCT4 expressions positively correlated with increased prostate tumor Gleason score. In primary glioma-derived CD133 negative cells, hypoxia was able to induce neurospheres and hESC markers. Together, these findings suggest that HIF targets may act as key inducers of a dynamic state of stemness in pathologic conditions. <i>Cancer Res; 71(13); 4640–52. ©2011 AACR</i>.</p></div>

The biology of the alpha subunits of hypoxia-inducible factors (HIFalpha) has expanded from their role in angiogenesis to their current position in the self-renewal and differentiation of stem cells. The results reported in this article show the discovery of FM19G11, a novel chemical entity that inhibits HIFalpha proteins that repress target genes of the two alpha subunits, in various tumor cell lines as well as in adult and embryonic stem cell models from rodents and humans, respectively. FM19G11 inhibits at nanomolar range the transcriptional and protein expression of Oct4, Sox2, Nanog, and Tgf-alpha undifferentiating factors, in adult rat and human embryonic stem cells, FM19G11 activity occurs in ependymal progenitor stem cells from rats (epSPC), a cell model reported for spinal cord regeneration, which allows the progression of oligodendrocyte cell differentiation in a hypoxic environment, has created interest in its characterization for pharmacological research. Experiments using small interfering RNA showed a significant depletion in Sox2 protein only in the case of HIF2alpha silencing, but not in HIF1alpha-mediated ablation. Moreover, chromatin immunoprecipitation data, together with the significant presence of functional hypoxia response element consensus sequences in the promoter region of Sox2, strongly validated that this factor behaves as a target gene of HIF2alpha in epSPCs. FM19G11 causes a reduction of overall histone acetylation with significant repression of p300, a histone acetyltransferase required as a co-factor for HIF-transcription activation. Arrays carried out in the presence and absence of the inhibitor showed the predominant involvement of epigenetic-associated events mediated by the drug.

Highlights from Recent Cancer Literature

The fragile histidine triad (FHIT) gene is a putative tumor suppressor gene that is thought to be involved in the carcinogenesis of breast cancer. Loss of FHIT expression has been observed in up to 72% of breast cancers and has been associated with increased p53, a high proliferation index, and increased tumor size and grade. However, loss of FHIT expression has not been investigated in association with apoptosis and cyclooxygenase-2 (COX-2) expression in breast cancer. Furthermore, expression of FHIT in primary breast tumors and their metastatic axillary lymph nodes has also not been previously described. The purpose of this study was to evaluate the expression of FHIT, COX-2, bcl-2, and p53 in primary breast tumor tissue; correlate their expression with known clinical and pathologic markers; and in cases when tissue was available, evaluate the expression of FHIT and COX-2 in the corresponding metastatic axillary lymph node in the same patient. Primary breast tumor specimens from 80 patients were examined for the presence of FHIT, COX-2, bcl-2, and p53 expression by immunohistochemistry using standard methods. When tissue was available, the expression of FHIT and COX-2 was also evaluated in the corresponding metastatic axillary lymph node specimen. FHIT expression in primary breast tumors was 56%. There was a significant correlation between FHIT expression in primary breast tumor and bcl-2 expression (P = 0.017). We also observed a significant inverse correlation between FHIT expression in primary breast tumor tissue and p53 expression (P = 0.023) in lymph node-negative cases. A significant inverse correlation between FHIT expression in the primary tumor and Ki-67 (P = 0.009) was also observed in lymph node-negative cases. FHIT expression in primary tumors correlated with FHIT expression in the metastatic lymph node (52.5%; P = 0.001). FHIT expression in primary tumors did not correlate with COX-2 expression. Our results suggest that loss of FHIT expression in breast cancer is associated with poor prognostic features. Furthermore, loss of FHIT expression is also seen in metastatic axillary lymph node. The prognostic and predictive value of these findings needs to be further evaluated in larger trials with longer follow-up.

643 Background: Agents targeting the PD-1 pathway have improved outcomes in RCC. CD73 may be an additional mechanism which tumors can exploit for immune evasion. It is regulated by hypoxia inducible factor (HIF) and converts AMP to adenosine. The resulting increase in extracellular adenosine can inhibit T-cell effector function. We evaluated CD73 expression in primary and metastatic tumor samples in patients with RCC. Methods: A commercial TMA (US Biomax) consisting of 31 primary clear cell RCC samples (2 with sarcomatoid features) with 8 matched and 1 unmatched metastases was used to assess CD73 expression. A genitourinary pathologist (OH) confirmed pathology and grade. Immunohistochemistry (IHC) was performed using a monoclonal anti-CD73 antibody (Cell Signaling; D7F9A). A combined score (CS: % of cells positive x intensity) was employed to quantify CD73 expression. Expression levels between matched primary and metastatic tissue was compared using Wilcoxon signed-rank test. Correlation of CD73 expression (CS > 0) in primary tumor with baseline clinical and pathologic characteristics was assessed using Kruskal-Wallis and Fisher's exact tests. Overall survival (OS) was estimated using the Kaplan-Meier method. Comparison between CD73 expression groups used log rank test. Results: CD73 expression was seen in 19% (n = 6) of primary and 66.7% (n = 6) of metastatic samples. Among matched primary and metastatic samples (n = 8 each), median CS was 25 (Q1-Q3:0-105) in metastatic samples while none of the corresponding primary samples demonstrated CD73 expression (median CS = 0, p = 0.062). CD73 expression in primary tumor samples did not correlate with baseline clinical or pathologic features. Five-year OS was 50% in patients who expressed CD73 in primary tumors compared to 84% in those who did not (p = 0.26). Conclusions: We observed a numerical increase in CD73 expression in metastatic tissue compared to primary RCC samples and worse 5 year OS. The small number of samples has limited statistical significance. Further studies are needed to examine the impact of CD73 expression on outcomes in RCC patients treated with currently approved checkpoint inhibitors and the investigational CD73 antagonists that are in early phases of development.

543P - Mir-31-3P is a Predictive Biomarker of Cetuximab Effects in a Post-Hoc Analysis in the New Epoc Study

Purpose: Primary brain tumors are common type of neoplasms. The most common are astrocytic tumors, so do meningiomas of various grades. The etiology is still unknown; however, there are lots of data presenting new theories about genetic alterations responsible for low- or high-grade astrocytic tumors development as well as meningiomas, despite this the results are divergent. The aim of the study was to evaluate hypoxia-inducible factor-1 (HIF-1) expression in meningiomas and astrocytic tumors of various grades. Material and methods: One hundred six cases of astrocytic tumors were divided into diffused astrocytoma (24 cases), anaplastic astrocytoma (40 cases) and glioblastoma groups (42 cases). Among glioblastoma group, 30 cases were secondary glioblastoma. One hundred fifty-four meningioma cases were divided as low-grade meningioma (G1: 104 cases) and high-grade meningioma groups (G2: 43 cases and G3: 7 cases). Twelve low-grade meningiomas transformed into high-grade tumors, 17 low-grade meningiomas recur within 12 years. HIF-1 expression was estimated using immunohistochemistry under the light microscope. Statistical analysis was performed in all examined groups. Results: HIF-1 expression was observed in 37.5% cases of diffused astrocytomas, in anaplastic astrocytomas 27.5% tumors were HIF-1 positive, in the glioblastoma goup HIF-1 expression was observed in 83.3% cases. All secondary glioblastomas were positive for HIF-1. Low-grade meningiomas were positive for HIF-1 in 55.7%, in high-grade meningiomas, HIF-1 expression was observed in 84%. All meningiomas, which progressed from low- to high-grade meningiomas, were HIF-1 positive. Conclusion: HIF-1 expression is associated with the development and progression of both astrocytic tumors and meningiomas.

High Epidermal Growth Factor Receptor Expression in Metastatic Colorectal Cancer Lymph Nodes May Be More Prognostic of Poor Survival Than in Primary Tumor

617 - WNT 5A Expression Has Assocation with VEGFR and MMP-9 Expression in Primary or Metastatic Tumor Tissue in Colorectal Cancer

10077 Background: Pelvic lymph node metastases are associated with a greater risk of prostate cancer recurrence and peripheral metastasis. Unfortunately, markers predictive of lymph node metastasis and/or recurrence after radical prostatectomy are limited and new molecular markers are needed to identify patients at higher risk of progression. NF-kB (p65) is a candidate molecular marker already associated with poor clinical outcomes such as biochemical recurrence and bone metastasis. We have also reported elevated nuclear p65 expression in prostate cancer lymph node metastasis. Pertinent to this issue, we tested whether the nuclear localization of p65 in radical prostatectomy specimens could predict the presence of lymph node metastases. Methods: Following informed consent, 51 patients who underwent radical prostatectomy were included in the study: 20 patients had lymph node metastasis at surgery and 31 patients had no evidence of lymph node metastasis and were used as the control group. All cases in the control group had no biochemical relapse 5 years following radical prostatectomy. NF-kB expression in prostate tumor sections was assessed by immunohistochemistry using a monoclonal NF-kB p65 antibody. The relation between nuclear p65 expression in primary tumors and lymph node metastasis was tested in univariate and multivariate Cox regression models. Results: Primary tumors of metastatic patients had an average of 21.25% of tumor cells with nuclear p65 expression as opposed to 9.42% of tumor cells of control patients (p=0.001). Univariate Cox regression demonstrated a 7.5% increased risk of having lymph node metastases for each percent increase in p65 nuclear staining (p=0.003). In the multivariate model, after controlling for pre-operative PSA (p=0.175), Gleason patterns (p=0.382), pathological stage (p=0.436), extracapsular extension (p=0.243) and seminal vesicle invasion (p=0.016), nuclear p65 was associated with an 8.8% increased risk for lymph node metastases (p=0.024). Conclusion: In univariate and multivariate analyses, p65 nuclear expression was strongly predictive of lymph node invasion. We propose that nuclear NF-kB (p65) may serve as a useful independent molecular marker for stratifying patients at risk for lymph node metastases. No significant financial relationships to disclose.

The p53 tumor suppressor gene product participated in G1 cell cycle arrest or cell death. Loss of function was associated with poor outcome in patients with breast carcinoma. bcl-2 prevented apoptosis induced by c-myc or growth factor deprivation. High bcl-2 expression in breast tumor tissue specimens appears to be associated with favorable prognostic factors. However, Bcl-2 and p53 expression in primary tumor tissue specimens versus metastatic lymph node specimens in breast carcinoma has not been studied. The current study compared Bcl-2 and p53 expression in primary breast carcinoma tissue specimens with Bcl-2 and p53 expression in axillary lymph node specimens. Primary breast tumor and corresponding axillary metastatic lymph node tissue specimens were obtained from 60 patients with breast carcinoma. They were evaluated for the presence of Bcl-2 and p53 expression by immunohistochemistry using standard methods. Bcl-2 expression in primary tumor tissue specimens (53%) was correlated with Bcl-2 expression in metastatic lymph node specimens (50 %; Pearson correlation = 0.656). p53 expression in primary tumor specimens (72%) was correlated with p53 expression in metastatic lymph node specimens (60 %; Pearson correlation = 0.800). A significant inverse correlation also was found between p53 and Bcl-2 expression in primary breast tumor tissue specimens (Pearson correlation = -0.310). The current study suggested that Bcl-2 and p53 expression in axillary metastatic lymph node specimens is correlated with Bcl-2 and p53 expression in the primary tumor tissue specimens. The prognostic and predictive value of Bcl-2 and p53 expression in axillary lymph node metastasis in patients with breast carcinoma needs to be further evaluated in larger trials with longer follow-up.

Hypoxia-Independent Downregulation of Hypoxia-Inducible Factor 1 Targets by Androgen Deprivation Therapy in Prostate Cancer

Chemokine receptor 4 (CXCR4) has been demonstrated to have a critical role in the early metastatic process. The aim of this study was to evaluate the prognostic value of CXCR4 expression in primary breast tumors and describe correlations with the occurrence of metastasis in organs expressing the CXCR4 ligand stromal cell-derived factor 1 (i.e., liver, lung, brain, and bone). CXCR4 expression in primary breast tumors was evaluated by immunohistochemistry in 823 patients included in two prospective clinical trials. CXCR4 expression was considered positive when >1% of tumor cells were stained. The prognostic value of CXCR4 expression was assessed by a Cox regression model adjusted for clinical characteristics. We assessed the association of CXCR4 expression with the rate of distant metastasis to specific organ sites. CXCR4 was expressed in 92 of 794 primary tumors (12%). CXCR4 expression was not associated with clinical characteristics. CXCR4 was not prognostic for overall survival and showed a nonsignificant trend toward a higher risk for distant metastasis. CXCR4(+) tumors showed a significantly higher risk for bone metastasis. The 10-year incidences of bone metastases were 23% (13.6%-32.6%) and 12% (9.7%-15%) in CXCR4(+) and CXCR4(-) tumors, respectively. This study suggests that expression of CXCR4 in primary breast tumors is associated with a higher likelihood of developing bone metastases. This finding could open new avenues for the development of novel adjuvant strategies, including bone-targeting agents.

ObjectivesPrevious studies noted discordance of programmed death‐1 (PD‐1) and one of its ligands (PD‐L1) across patient‐matched primary and metastatic clear cell renal cell carcinoma (ccRCC). There are inconsistencies if the primary or metastatic tumor has higher expression, and whether metastatic tumor expression is associated with patient outcome. Thus, we examined PD‐1 and PD‐L1 in patient‐matched tumors using a large number of ccRCC patients with long follow‐up.Materials and MethodsWe analyzed PD‐1 and PD‐L1 using immunohistochemistry in patient‐matched primary and metastatic tumors from 110 ccRCC patients. Concordance was assessed among longitudinal metastatic tumors, as well as across patient‐matched primary and metastatic tumors. Cox proportional hazards regression was used to evaluate the associations of metastatic tumor expression with cancer‐specific survival.ResultsWe observed inter‐metastatic tumor heterogeneity of PD‐1 in 25 (69%) of the 36 patients and of PD‐L1 in seven (19%) patients. Concordance between patient‐matched primary and metastatic tumors was 73% (Kappa = 0.16, 95% CI: −0.003‐0.32). Similarly, concordance of PD‐L1 between metastatic and patient‐matched primary tumors was 78% (Kappa = 0.27, 95% CI: 0.09‐0.46). Both markers demonstrated higher expression in primary vs metastatic tumors. Metastatic tumor expression of PD‐1 was significantly associated with metastatic location (P < .0001) and ccRCC‐specific survival (HR = 2.15, 95% CI: 1.06‐4.36, P = .035).ConclusionsThe expression of PD‐1 and PD‐L1 is discordant across patient‐matched ccRCC tumors, with higher expression in primary tumors. Higher PD‐1 expression was associated with metastatic location and lower cancer‐specific survival. If validated, these results highlight the importance of evaluating these biomarkers in metastatic tissue specifically.