Erythropoietin receptor expression in biopsy specimens from patients with uterine cervix squamous cell carcinoma

Erythropoietin Receptor Antagonist Suppressed Ectopic Hemoglobin Synthesis in Xenografts of HeLa Cells to Promote Their Destruction

The aim of this study is to explore a cause-oriented therapy for patients with uterine cervical cancer that expresses erythropoietin (Epo) and its receptor (EpoR). Epo, by binding to EpoR, stimulates the proliferation and differentiation of erythroid progenitor cells into hemoglobin-containing red blood cells. In this study, we report that the HeLa cells in the xenografts expressed ε, γ, and α globins as well as myoglobin (Mb) to produce tetrameric α2ε2 and α2γ2 and monomeric Mb, most of which were significantly suppressed with an EpoR antagonist EMP9. Western blotting revealed that the EMP9 treatment inhibited the AKT-pAKT, MAPKs-pMAPKs, and STAT5-pSTAT5 signaling pathways. Moreover, the treatment induced apoptosis and suppression of the growth and inhibited the survival through disruption of the harmonized hemoprotein syntheses in the tumor cells concomitant with destruction of vascular nets in the xenografts. Furthermore, macrophages and natural killer (NK) cells with intense HIF-1α expression recruited significantly more in the degenerating foci of the xenografts. These findings were associated with the enhanced expressions of nNOS in the tumor cells and iNOS in macrophages and NK cells in the tumor sites. The treated tumor cells exhibited a substantial number of perforations on the cell surface, which indicates that the tumors were damaged by both the nNOS-induced nitric oxide (NO) production in the tumor cells as well as the iNOS-induced NO production in the innate immune cells. Taken together, these data suggest that HeLa cells constitutively acquire ε, γ and Mb synthetic capacity for their survival. Therefore, EMP9 treatment might be a cause-oriented and effective therapy for patients with squamous cell carcinoma of the uterine cervix.

Long-term results of radiation therapy oncology group 9903: a randomized phase 3 trial to assess the effect of erythropoietin on local-regional control in anemic patients treated with radiation therapy for squamous cell carcinoma of the head and neck

PURPOSE

This paper reports long-term results of RTOG 9903, to determine whether the addition of erythropoietin (EPO) would improve the outcomes of radiation therapy (RT) in mildly to moderately anemic patients with head and neck squamous cell carcinoma (HNSCCa).

METHODS AND MATERIALS

The trial included HNSCCa patients treated with definitive RT. Patients with stage III or IV disease received concomitant chemoradiation therapy or accelerated fractionation. Pretreatment hemoglobin levels were required to be between 9.0 and 13.5 g/dL (12.5 g/dL for females). EPO, 40,000 U, was administered weekly starting 7 to 10 days before RT was initiated in the RT + EPO arm.

RESULTS

A total of 141 of 148 enrolled patients were evaluable. The baseline median hemoglobin level was 12.1 g/dL. In the RT + EPO arm, the mean hemoglobin level at 4 weeks increased by 1.66 g/dL, whereas it decreased by 0.24 g/dL in the RT arm. With a median follow-up of 7.95 years (range: 1.66-10.08 years) for surviving patients and 3.33 years for all patients (range: 0.03-10.08 years), the 5-year estimate of local-regional failure was 46.2% versus 39.4% (P=.42), local-regional progression-free survival was 31.5% versus 37.6% (P=.20), and overall survival was 36.9% versus 38.2% (P=.54) for the RT + EPO and RT arms, respectively. Late toxicity was not different between the 2 arms.

CONCLUSIONS

This long-term analysis confirmed that despite the ability of EPO to raise hemoglobin levels in anemic patients with HNSCCa, it did not improve outcomes when added to RT. The possibility of a detrimental effect of EPO could not be ruled out.

Co-stimulation with stem cell factor and erythropoietin enhances migration of c-Kit expressing cervical cancer cells through the sustained activation of ERK1/2

The cytokines erythropoietin (Epo) and stem cell factor (SCF), coupled with the cooperation between their receptors (EpoR and c-Kit), are essential components of normal physiological erythropoiesis. In earlier studies, we demonstrated the expression of c-Kit and EpoR in cervical cancer cells. It was identified that SCF is a survival factor, whereas Epo promotes cell proliferation. Cooperation between EpoR and SCF in cervical cancer has rarely been studied, despite the fact that cell migration and anchorage independent growth are considered initial steps in metastasis. Thus, the aim of this study was to analyse the effect of SCF and Epo alone, or in combination, on the migration and anchorage independent growth of two cervical cancer-derived cell lines. First, we demonstrated the expression of EpoR and c-Kit in the cell lines. Next, we evaluated anchorage independent growth, and identified that Epo and SCF produced a modest number of colonies, whereas the combination Epo/SCF induced a significantly higher number of colonies. Migration was then evaluated in Boyden chambers. Co-stimulation with Epo/SCF induced a significantly higher number of migrating cells than either cytokine alone. SCF-, Epo- and Epo/SCF-induced migration was inhibited by blocking phosphorylation of Janus kinase 2 (JAK2). Accordingly, western blot analysis demonstrated that the JAK2/signal transducer and activator of transcription-5 (STAT5) axis was activated in all cases. By contrast, inhibition of extracellular signal-related kinase (ERK) 1/2 abrogated migration induced by SCF and Epo/SCF only. Concurrently, Epo induced a modest, transient activation of ERK1/2, whereas SCF and Epo/SCF prompted a strong, sustained phosphorylation of ERK1/2. The results from this study have revealed that co-stimulation with Epo/SCF promotes migration and anchorage independent cell growth, and that co-signalling from EpoR and c-Kit converge on JAK2/STAT5 activation. Furthermore, SCF- and Epo/SCF-induced migration depends on the sustained activation of ERK1/2. These results indicate that co-signalling from different cytokine receptors induces migration, and this suggests that migratory behaviour may be regulated by the cooperative activity of Epo and SCF in cells expressing their cognate receptors.

Association between pharmaceutical support and basic science research on erythropoiesis-stimulating agents

BACKGROUND

To our knowledge, no prior research has evaluated the association between pharmaceutical industry funding and basic science research results. When erythropoiesis-stimulating agents (ESAs) were licensed to treat chemotherapy-associated anemia, basic science concerns related to potential cancer stimulation were raised. We evaluated associations between pharmaceutical industry support and reported findings evaluating ESA effects on cancer cells.

METHODS

Articles identified in MEDLINE and EMBASE databases (1988-2008) investigating basic science findings related to ESA administration in the solid tumor setting were reviewed. Outcomes included information on erythropoietin receptors (EpoRs), Epo-induced signaling events, cellular function, and qualitative conclusions. Information on study funding (academic investigators with no reported funding from ESA manufacturers [64 studies], academic investigators with grant funding from ESA manufacturers [7 studies], and investigators employed by the ESA manufacturers [3 studies]) was evaluated. Some studies did not include information on each outcome.

RESULTS

Investigators without funding from ESA manufacturers were more likely than academic investigators with such funding or investigators employed by ESA manufacturers to identify EpoRs on solid tumor cells (100%, 60%, and 67%, respectively; P = .009), Epo-induced signaling events (94%, 0%, and 0%, respectively; P = .001), or changes in cellular function (57%, 0%, and 0%, respectively; P = .007) and to conclude that ESAs had potentially harmful effects on cancer cells (57%, 0%, and 0%, respectively; P = .008).

CONCLUSIONS

Researchers who do not have pharmaceutical industry support are more likely than those with pharmaceutical support to identify detrimental in vitro effects of ESAs. The potential for conflicts of interest to affect basic science research should be considered.

Erythropoietin stimulates cancer cell migration and activates RhoA protein through a mitogen-activated protein kinase/extracellular signal-regulated kinase-dependent mechanism

Erythropoietin (Epo) receptor (EpoR) is expressed in several cancer cell lines, and the functional consequence of this expression is under extensive study. In this study, we used a cervical cancer cell line in which EpoR was first found to be expressed and to correlate with the severity of the disease. We demonstrate that Epo is a chemoattractant for these cancer cells, enhancing their migration under serum-starved conditions. Using a Transwell migration system, we show that Epo enhances cancer cell migration in a dose- and time-dependent manner. The effect of Epo is dependent on the activity of two signaling pathways: the mitogen-activated protein kinase (MAPK) pathway and the RhoA GTPase pathway. We show that Epo activates both pathways in a Janus kinase-dependent manner and that this activation is required for Epo effects on cell migration. Furthermore, we use both pharmacological and genetic inhibitors to demonstrate that the activation of RhoA GTPase is dependent on the activity of the MAPK pathway, providing the first evidence for interaction between these two signaling cascades.