Expression of ErbB2 enhances radiation-induced NF-kappaB activation

Alpha Particle-Emitting Radiopharmaceuticals as Cancer Therapy: Biological Basis, Current Status, and Future Outlook for Therapeutics Discovery

Critical advances in radionuclide therapy have led to encouraging new options for cancer treatment through the pairing of clinically useful radiation-emitting radionuclides and innovative pharmaceutical discovery. Of the various subatomic particles used in therapeutic radiopharmaceuticals, alpha (α) particles show great promise owing to their relatively large size, delivered energy, finite pathlength, and resulting ionization density. This review discusses the therapeutic benefits of α-emitting radiopharmaceuticals and their pairing with appropriate diagnostics, resulting in innovative "theranostic" platforms. Herein, the current landscape of α particle-emitting radionuclides is described with an emphasis on their use in theranostic development for cancer treatment. Commonly studied radionuclides are introduced and recent efforts towards their production for research and clinical use are described. The growing popularity of these radionuclides is explained through summarizing the biological effects of α radiation on cancer cells, which include DNA damage, activation of discrete cell death programs, and downstream immune responses. Examples of efficient α-theranostic design are described with an emphasis on strategies that lead to cellular internalization and the targeting of proteins involved in therapeutic resistance. Historical barriers to the clinical deployment of α-theranostic radiopharmaceuticals are also discussed. Recent progress towards addressing these challenges is presented along with examples of incorporating α-particle therapy in pharmaceutical platforms that can be easily converted into diagnostic counterparts.

Rel-A/PACER/miR 7 Axis May Play a Role in Radiotherapy Treatment in Breast Cancer Patients

Background

Radiotherapy has become the standard form of treatment for breast cancer (BC). Radioresistance is an issue that limits the effectiveness of radiotherapy (RT). Therefore, predictive biomarkers are needed to choose the appropriate RT for the patient. Activation of the proinflammatory transcription factor, nuclear factor-kappa B (NF-κB), is a frequently noted pathway in BC. Investigating the relationship between RT and alterations in gene expression involved in the immune pathway can help better control the disease. This research investigated the impact of RT on the expression levels of Rel-A, PACER, and miR-7 within the NF-κB signaling pathway.

Methods

Blood samples (n = 15) were obtained from BC patients during four different time intervals: 72 hours prior to initiating RT, as well as one, two, and four weeks following RT completion. Samples were also collected from 20 healthy women who had no immune or cancer-related diseases. Blood RNA was extracted, and complementary DNA was synthesized. Gene expression level was determined using R real-time polymerase chain reaction (RT-PCR).

Results

There was a significant difference in the expression level of Rel-A between patients and normal individual blood samples (p < 0.05). After four weeks of RT, qRT-PCR revealed a significant downregulation of miR-7 and upregulation of Rel-A and PACER in BC patients. Also, there was a significant association between Rel-A expression and monocyte numbers during RT (p < 0.001).

Conclusion

The expression level of PACER, miR-7 and Rel-A, changed after RT; therefore, these genes could be used as diagnostic and therapeutic RT markers in BC.

RNF126-Mediated MRE11 Ubiquitination Activates the DNA Damage Response and Confers Resistance of Triple-Negative Breast Cancer to Radiotherapy

Triple-negative breast cancer (TNBC) has higher molecular heterogeneity and metastatic potential and the poorest prognosis. Because of limited therapeutics against TNBC, irradiation (IR) therapy is still a common treatment option for patients with lymph nodes or brain metastasis. Thus, it is urgent to develop strategies to enhance the sensitivity of TNBC tumors to low-dose IR. Here, the authors report that E3 ubiquitin ligase Ring finger protein 126 (RNF126) is important for IR-induced ATR-CHK1 pathway activation to enhance DNA damage repair (DDR). Mechanistically, RNF126 physically associates with the MRE11-RAD50-NBS1 (MRN) complex and ubiquitinates MRE11 at K339 and K480 to increase its DNA exonuclease activity, subsequent RPA binding, and ATR phosphorylation, promoting sustained DDR in a homologous recombination repair-prone manner. Accordingly, depletion of RNF126 leads to increased genomic instability and radiation sensitivity in both TNBC cells and mice. Furthermore, it is found that RNF126 expression is induced by IR activating the HER2-AKT-NF-κB pathway and targeting RNF126 expression with dihydroartemisinin significantly improves the sensitivity of TNBC tumors in the brain to IR treatment in vivo. Together, these results reveal that RNF126-mediated MRE11 ubiquitination is a critical regulator of the DDR, which provides a promising target for improving the sensitivity of TNBC to radiotherapy.

A Review of Radiation-Induced Alterations of Multi-Omic Profiles, Radiation Injury Biomarkers, and Countermeasures

Increasing utilization of nuclear power enhances the risks associated with industrial accidents, occupational hazards, and the threat of nuclear terrorism. Exposure to ionizing radiation interferes with genomic stability and gene expression resulting in the disruption of normal metabolic processes in cells and organs by inducing complex biological responses. Exposure to high-dose radiation causes acute radiation syndrome, which leads to hematopoietic, gastrointestinal, cerebrovascular, and many other organ-specific injuries. Altered genomic variations, gene expression, metabolite concentrations, and microbiota profiles in blood plasma or tissue samples reflect the whole-body radiation injuries. Hence, multi-omic profiles obtained from high-resolution omics platforms offer a holistic approach for identifying reliable biomarkers to predict the radiation injury of organs and tissues resulting from radiation exposures. In this review, we performed a literature search to systematically catalog the radiation-induced alterations from multi-omic studies and radiation countermeasures. We covered radiation-induced changes in the genomic, transcriptomic, proteomic, metabolomic, lipidomic, and microbiome profiles. Furthermore, we have covered promising multi-omic biomarkers, FDA-approved countermeasure drugs, and other radiation countermeasures that include radioprotectors and radiomitigators. This review presents an overview of radiation-induced alterations of multi-omics profiles and biomarkers, and associated radiation countermeasures.

Clinical Profile and Outcome of Patients With Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer With Brain Metastases: Real-World Experience

PURPOSE

There are sparse data in patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer with brain metastases from real-world settings, especially where access to newer targeted therapies is limited.

METHODS

This was a single institution, retrospective cohort study of patients with HER2-positive breast cancer diagnosed between January 2013 and December 2017 to have brain metastases and treated with any HER2-targeted therapy. The main objectives were to estimate progression-free survival (PFS) and overall survival (OS) from the time of brain metastases.

RESULTS

A total of 102 patients with a median age of 52 (interquartile range, 45-57) years were included, of whom 63 (61.8%) had received one line and 14 (13.7%) had received two lines of HER2-targeted therapies before brain metastasis, 98 (96.1%) were symptomatic at presentation, 22 (25.3%) had solitary brain lesion, 22 (25.3%) had 2-5 lesions, and 43 (49.4%) had ≥ 5 lesions. Local treatment included surgical resection in nine (8.9%) and radiotherapy in all (100%) patients. The first HER2-targeted therapy after brain metastasis was lapatinib in 71 (68.6%), trastuzumab in 19 (18.6%), lapatinib and trastuzumab in three (2.9%), trastuzumab emtansine in four (3.9%), and intrathecal trastuzumab in five (4.9%) patients. At a median follow-up of 13.9 months, the median PFS and OS were 8 (95% CI, 6.2 to 9.8) months and 14 (95% CI, 10.8 to 17.2) months, respectively, with a 2-year OS of 25% (95% CI, 16.7 to 34.4). The median PFS in patients who received lapatinib-capecitabine regimen (n = 62) was 9.0 (95% CI, 7.3 to 10.7) months.

CONCLUSION

There was a substantial clinical benefit of local and systemic therapy in patients with brain metastases and HER2-positive disease in a real-world setting with limited access to newer HER2-targeted drugs.

Androgen and oestrogen receptor co-expression determines the efficacy of hormone receptor-mediated radiosensitisation in breast cancer

PURPOSE

Radiation therapy (RT) and hormone receptor (HR) inhibition are used for the treatment of HR-positive breast cancers; however, little is known about the interaction of the androgen receptor (AR) and estrogen receptor (ER) in response to RT in AR-positive, ER-positive (AR+/ER+) breast cancers. Here we assessed radiosensitisation of AR+/ER+ cell lines using pharmacologic or genetic inhibition/degradation of AR and/or ER.

METHODS

Radiosensitisation was assessed with AR antagonists (enzalutamide, apalutamide, darolutamide, seviteronel, ARD-61), ER antagonists (tamoxifen, fulvestrant) or using knockout of AR.

RESULTS

Treatment with AR antagonists or ER antagonists in combination with RT did not result in radiosensitisation changes (radiation enhancement ratios [rER]: 0.76-1.21). Fulvestrant treatment provided significant radiosensitisation of CAMA-1 and BT-474 cells (rER: 1.06-2.0) but not ZR-75-1 cells (rER: 0.9-1.11). Combining tamoxifen with enzalutamide did not alter radiosensitivity using a 1 h or 1-week pretreatment (rER: 0.95-1.14). Radiosensitivity was unchanged in AR knockout compared to Cas9 cells (rER: 1.07 ± 0.11), and no additional radiosensitisation was achieved with tamoxifen or fulvestrant compared to Cas9 cells (rER: 0.84-1.19).

CONCLUSION

While radiosensitising in AR + TNBC, AR inhibition does not modulate radiation sensitivity in AR+/ER+ breast cancer. The efficacy of ER antagonists in combination with RT may also be dependent on AR expression.

Quantifying the Effects of Combination Trastuzumab and Radiation Therapy in Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer

Background: Trastuzumab induces cell cycle arrest in HER2-overexpressing cells and demonstrates potential in radiosensitizing cancer cells. The purpose of this study is to quantify combination trastuzumab and radiotherapy to determine their synergy. Methods: In vitro, HER2+ cancer cells were treated with trastuzumab, radiation, or their combination, and imaged to evaluate treatment kinetics. In vivo, HER2+ tumor-bearing mice were treated with trastuzumab and radiation, and assessed longitudinally. An additional cohort was treated and sacrificed to quantify CD45, CD31, α-SMA, and hypoxia. Results: The interaction index revealed the additive effects of trastuzumab and radiation in vitro in HER2+ cell lines. Furthermore, the results revealed significant differences in tumor response when treated with radiation (p < 0.001); however, no difference was seen in the combination groups when trastuzumab was added to radiotherapy (p = 0.56). Histology revealed increases in CD45 staining in tumors receiving trastuzumab (p < 0.05), indicating potential increases in immune infiltration. Conclusions: The in vitro results showed the additive effect of combination trastuzumab and radiotherapy. The in vivo results showed the potential to achieve similar efficacy of radiotherapy with a reduced dose when combined with trastuzumab. If trastuzumab and low-dose radiotherapy induce greater tumor kill than a higher dose of radiotherapy, combination therapy can achieve a similar reduction in tumor burden.

Phytochemicals: Potential Therapeutic Modulators of Radiation Induced Signaling Pathways

Ionizing radiation results in extensive damage to biological systems. The massive amount of ionizing radiation from nuclear accidents, radiation therapy (RT), space exploration, and the nuclear battlefield leads to damage to biological systems. Radiation injuries, such as inflammation, fibrosis, and atrophy, are characterized by genomic instability, apoptosis, necrosis, and oncogenic transformation, mediated by the activation or inhibition of specific signaling pathways. Exposure of tumors or normal cells to different doses of ionizing radiation could lead to the generation of free radical species, which can release signal mediators and lead to harmful effects. Although previous FDA-approved agents effectively mitigate radiation-associated toxicities, their use is limited due to their high cellular toxicities. Preclinical and clinical findings reveal that phytochemicals derived from plants that exhibit potent antioxidant activities efficiently target several signaling pathways. This review examined the prospective roles played by some phytochemicals in altering signal pathways associated with radiation response.

Comparison of Radiation With or Without Concurrent Trastuzumab for HER2-Positive Ductal Carcinoma In Situ Resected by Lumpectomy: A Phase III Clinical Trial

PURPOSE

Preclinical studies report that trastuzumab (T) can boost radiotherapy (RT) effectiveness. The primary aim of the B-43 trial was to assess the efficacy of RT alone vs concurrent RT plus T in preventing recurrence of ipsilateral breast cancer (IBTR) in women with ductal carcinoma in situ (DCIS).

PATIENTS AND METHODS

Eligibility: Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1, DCIS resected by lumpectomy, known estrogen receptor (ER) and/or progesterone receptor (PgR), and human epidermal growth factor receptor 2 (HER2) status by centralized testing. Whole-breast RT was given concurrently with T. Stratification was by menopausal status, adjuvant endocrine therapy plan, and nuclear grade. Definitive intent-to-treat primary analysis was to be conducted when either 163 IBTR events occurred or all accrued patients were on study ≥ 5 years.

RESULTS

There were 2,014 participants who were randomly assigned. Median follow-up time as of December 31, 2019, was 79.2 months. At primary definitive analysis, 114 IBTR events occurred: RT arm, 63 and RT plus T arm, 51 (hazard ratio [HR], 0.81; 95% CI, 0.56 to 1.17; P value = .26). There were 34 who were invasive: RT arm, 18 and RT plus T arm, 20 (HR, 1.11; 95% CI, 0.59 to 2.10; P value = .71). Seventy-six were DCIS: RT arm, 45 and RT plus T arm, 31 (HR, 0.68; 95% CI, 0.43 to 1.08; P value = .11). Annual IBTR event rates were: RT arm, 0.99%/y and RT plus T arm, 0.79%/y. The study did not reach the 163 protocol-specified events, so the definitive analysis was triggered by all patients having been on study for ≥ 5 years.

CONCLUSION

Addition of T to RT did not achieve the objective of 36% reduction in IBTR rate but did achieve a modest but statistically nonsignificant reduction of 19%. Nonetheless, this trial had negative results. Further exploration of RT plus T is needed in HER2-positive DCIS before its routine delivery in patients with DCIS resected by lumpectomy.

Trastuzumab deruxtecan for the treatment of HER2-positive advanced gastric cancer: a clinical perspective

Human epidermal growth factor receptor 2 (HER2)-positive gastric cancer is a subtype for which new drugs and specific treatment strategies should be developed. Trastuzumab deruxtecan (T-DXd) is a novel HER2-targeted antibody-drug conjugate containing topoisomerase I inhibitor as a payload. In the randomized phase 2 study (DESTINY-Gastric01) for HER2-positive advanced gastric or gastroesophageal junction cancer (AGC), patients treated with T-DXd showed a significantly higher response rate compared with the chemotherapy of physician's choice, associated with remarkably prolonged progression-free and overall survival. T-DXd also exhibits anti-tumor activity to HER2-negative tumor cells close to HER2-positive cells (so-called bystander killing effect). T-DXd was effective even for HER2-low expressing breast and gastric cancer in several clinical studies. Taking advantage of these strong points and synergism with other cytotoxic, molecular-targeted and immunological agents, it is expected that T-DXd will bring further progression in treatment both for strongly and weakly HER2 positive AGC in various treatment settings including perioperative chemotherapy.

4-Methylumbelliferone administration enhances radiosensitivity of human fibrosarcoma by intercellular communication

Hyaluronan synthesis inhibitor 4-methylumbelliferone (4-MU) is a candidate of radiosensitizers which enables both anti-tumour and anti-metastasis effects in X-ray therapy. The curative effects under such 4-MU administration have been investigated in vitro; however, the radiosensitizing mechanisms remain unclear. Here, we investigated the radiosensitizing effects under 4-MU treatment from cell experiments and model estimations. We generated experimental surviving fractions of human fibrosarcoma cells (HT1080) after 4-MU treatment combined with X-ray irradiation. Meanwhilst, we also modelled the pharmacological effects of 4-MU treatment and theoretically analyzed the synergetic effects between 4-MU treatment and X-ray irradiation. The results show that the enhancement of cell killing by 4-MU treatment is the greatest in the intermediate dose range of around 4 Gy, which can be reproduced by considering intercellular communication (so called non-targeted effects) through the model analysis. As supposed to be the involvement of intercellular communication in radiosensitization, the oxidative stress level associated with reactive oxygen species (ROS), which leads to DNA damage induction, is significantly higher by the combination of 4-MU treatment and irradiation than only by X-ray irradiation, and the radiosensitization by 4-MU can be suppressed by the ROS inhibitors. These findings suggest that the synergetic effects between 4-MU treatment and irradiation are predominantly attributed to intercellular communication and provide more efficient tumour control than conventional X-ray therapy.

In vitro effects of Trastuzumab Emtansine (T-DM1) and concurrent irradiation on HER2-positive breast cancer cells

BACKGROUND

To determine the effects of concurrent irradiation and T-DM1 on HER2-positive breast cancer cell lines.

METHODS

Five human breast cancer cell lines (in vitro study) presenting various levels of HER2 expression were used to determine the potential therapeutic effect of T-DM1 combined with radiation. The toxicity of T-DM1 was assessed using viability assay and cell cycle analysis was performed by flow cytometry after BrdU incorporation. HER2 cells were irradiated at different dose levels after exposure to T-DM1. Survival curves were determined by cell survival assays (after 5 population doubling times).

RESULTS

The results revealed that T-DM1 induced significant lethality due to the intracellular action of DM1 on the cell cycle with significant G2/M phase blocking. Even after a short time incubation, the potency of T-DM1 was maintained and even enhanced over time, with a higher rate of cell death. After irradiation alone, the D₁₀ (dose required to achieve 10% cell survival) was significantly higher for high HER2-expressing cell lines than for low HER2-expressing cells, with a linearly increasing relationship. In combination with irradiation, using conditions that allow cell survival, T-DM1 does not induce a radiosensitivity.

CONCLUSIONS

Although there is a linear correlation between intrinsic HER2 expression and radioresistance, the results indicated that T-DM1 is not a radiation-sensitizer under the experimental conditions of this study that allowed cell survival. However, further investigations are needed, in particular in vivo studies before reaching a final conclusion.

The Role of the RANKL/RANK Axis in the Prevention and Treatment of Breast Cancer with Immune Checkpoint Inhibitors and Anti-RANKL

The receptor activator of nuclear factor-κB (RANK) and the RANK ligand (RANKL) were reported in the regulation of osteoclast differentiation/activation and bone homeostasis. Additionally, the RANKL/RANK axis is a significant mediator of progesterone-driven mammary epithelial cell proliferation, potentially contributing to breast cancer initiation and progression. Moreover, several studies supported the synergistic effect of RANK and epidermal growth factor receptor (EGFR) and described RANK's involvement in epidermal growth factor receptor 2 (ERBB2)-positive carcinogenesis. Consequently, anti-RANKL treatment has been proposed as a new approach to preventing and treating breast cancer and metastases. Recently, RANKL/RANK signaling pathway inhibition has been shown to modulate the immune environment and enhance the efficacy of anti-CTLA-4 and anti-PD-1 monoclonal antibodies against solid tumors. Clinical and experimental trials have emerged evaluating RANKL inhibition as an enhancer of the immune response, rendering resistant tumors responsive to immune therapies. Trials evaluating the combinatorial effect of immune checkpoint inhibitors and anti-RANKL treatment in double-positive (RANK+/ERBB2+) patients are encouraging.

Dual blockade of CD47 and HER2 eliminates radioresistant breast cancer cells

Although the efficacy of cancer radiotherapy (RT) can be enhanced by targeted immunotherapy, the immunosuppressive factors induced by radiation on tumor cells remain to be identified. Here, we report that CD47-mediated anti-phagocytosis is concurrently upregulated with HER2 in radioresistant breast cancer (BC) cells and RT-treated mouse syngeneic BC. Co-expression of both receptors is more frequently detected in recurrent BC patients with poor prognosis. CD47 is upregulated preferentially in HER2-expressing cells, and blocking CD47 or HER2 reduces both receptors with diminished clonogenicity and augmented phagocytosis. CRISPR-mediated CD47 and HER2 dual knockouts not only inhibit clonogenicity but also enhance macrophage-mediated attack. Dual antibody of both receptors synergizes with RT in control of syngeneic mouse breast tumor. These results provide the evidence that aggressive behavior of radioresistant BC is caused by CD47-mediated anti-phagocytosis conjugated with HER2-prompted proliferation. Dual blockade of CD47 and HER2 is suggested to eliminate resistant cancer cells in BC radiotherapy.

Diagnosis and Treatment of Bone Metastases in Breast Cancer: Radiotherapy, Local Approach and Systemic Therapy in a Guide for Clinicians

The standard care for metastatic breast cancer (MBC) is systemic therapies with imbrication of focal treatment for symptoms. Recently, thanks to implementation of radiological and metabolic exams and development of new target therapies, oligometastatic and oligoprogressive settings are even more common-paving the way to a paradigm change of focal treatments role. In fact, according to immunophenotype, radiotherapy can be considered with radical intent in these settings of patients. The aim of this literature review is to analyze available clinical data on prognosis of bone metastases from breast cancer and benefits of available treatments for developing a practical guide for clinicians.

ErbB3, a possible prognostic factor of head and neck squamous cell carcinoma

OBJECTIVE

We aimed to identify the prognostic factors in head and neck squamous cell carcinoma (HNSCC) by using gene expression analysis and candidate biomarkers for adjuvant therapy.

STUDY DESIGN

Complementary DNA (cDNA) microarray analysis was performed by using samples from 8 patients, who had died as a result of fulminant recurrence shortly after postoperative radiation therapy, and the results were compared with those from patients with HNSCC of similar stage, but without recurrence. Tissue microarray and immunohistochemistry of samples from 69 patients with oral cavity squamous cell carcinoma indicated ErbB3 to be a prognostic marker, and its expression was analyzed in the HNSCC cell lines. Sapitinib was tested as a concurrent inhibitor of EGFR, ErbB2, and ErbB3. In 15 mice, tumor xenograft was implanted at the lateral tongue, and tumor growth was evaluated.

RESULTS

ErbB3 overexpression in patients with treatment-resistant HNSCC was associated with relapse-free survival, disease-free survival, and overall survival (P = .018, P = .006, and P = .003, respectively). In the HNSCC cell line, ErbB2 and ErbB3 overexpression was inhibited by postoperative adjuvant therapy with sapitinib, which was also seen to improve survival in an animal model.

CONCLUSIONS

ErbB3 overexpression predicts a poor clinical outcome. Sapitinib was shown to be an effective inhibitor in the HNSCC cell line and animal models of cancer but with no statistical significance. Further studies with larger groups are needed to better support these results.

Immune targets in the tumor microenvironment treated by radiotherapy

Radiotherapy (RT), the major anti-cancer modality for more than half of cancer patients after diagnosis, has the advantage of local tumor control with relatively less systematic side effects comparing to chemotherapy. However, the efficacy of RT is limited by acquired tumor resistance leading to the risks of relapse and metastasis. To further enhance the efficacy of RT, with the renaissances of targeted immunotherapy (TIT), increasing interests are raised on RT combined with TIT including cancer vaccines, T-cell therapy, and antibody-based immune checkpoint blockers (ICB) such as anti-CTLA-4 and anti-PD1/PD-L1. In achieving a significant synergy between RT and TIT, the dynamics of radiation-induced response in tumor cells and stromal cells, especially the cross-talk between tumor cells and immune cells in the irradiated tumor microenvironment (ITME) as highlighted in recent literature are to be elucidated. The abscopal effect refereeing the RT-induced priming function outside of ITME could be compromised by the immune-suppressive factors such as CD47 and PD-L1 on tumor cells and Treg induced or enhanced in the ITME. Cell surface receptors temporally or permanently induced and bioactive elements released from dead cells could serve antigenic source (radiation-associated antigenic proteins, RAAPs) to the host and have functions in immune regulation on the tumor. This review is attempted to summarize a cluster of factors that are inducible by radiation and targetable by antibodies, or have potential to be immune regulators to synergize tumor control with RT. Further characterization of immune regulators in ITME will deepen our understanding of the interplay among immune regulators in ITME and discover new effective targets for the combined modality with RT and TIT.

Enhanced drug internalization and therapeutic efficacy of PEGylated nanoparticles by one-step formulation with anti-mPEG bispecific antibody in intrinsic drug-resistant breast cancer

One-step formulation of BsAb with PLD is a simple method to enhance tumor specificity, internalization and the anti-cancer activity.

Paeonol induces the apoptosis of the SGC‑7901 gastric cancer cell line by downregulating ERBB2 and inhibiting the NF‑κB signaling pathway

The purpose of the present study was to analyze the association between paeonol and the known genes related to gastric cancer (GC) using bioinformatics methods, and to investigate the role of paeonol in the potential impact on the nuclear factor‑κB (NF‑κB) signaling pathway, in order to provide a theoretical basis for further elucidating the effect of paeonol on cancer cells. Cell viability, morphology and apoptosis were detected using an MTT assay, an inverted microscope, and flow cytometry, respectively. The correlation between drugs and genes was analyzed using the Search Tool for Interactions of Chemicals (STITCH) gene‑drug interaction network. The expression levels of related mRNA and proteins were determined using reverse transcription‑quantitative polymerase chain reaction analysis and enzyme‑linked immunosorbent assay. The changes in protein expression were examined using western blot analysis. The correlation network between target genes directly affected by paeonol and known GC genes was determined by analyzing the association between the compounds and genes recorded in the STITCH database. The GC‑related epidermal growth factor receptor 2 (ERBB2) gene was at the core position of the paeonol interaction network and may be an important potential target gene for the effect of paeonol on cancer cells. The effect of paeonol on the viability of the SGC‑7901 GC cell line was detected using an MTT assay, which showed that the inhibitory effect occurred in a time‑ and dose‑dependent manner. The observations of cell morphology demonstrated that the cells were floating, abnormal in shape, had unclear boundaries and were sparse in arrangement following paeonol treatment. Flow cytometry indicated that paeonol significantly accelerated the apoptotic rate of the SGC‑7901 GC cells. The examination of clinical samples suggested that ERBB2 was expressed at a high level in GC samples, and was significantly downregulated following the addition of paeonol. The western blot analysis revealed that downregulating ERBB2 affected the activation of the NF‑κB signaling pathway, thereby upregulating the pro‑apoptotic factor B‑cell lymphoma‑associated X protein. Taken together, paeonol significantly downregulated ERBB2 and inhibited the activation of the NF‑κB signaling pathway, thereby inhibiting the proliferation of SGC‑7901 cells and inducing apoptosis.

Local and Regional Breast Cancer Recurrences: Salvage Therapy Options in the New Era of Molecular Subtypes

Isolated local or regional recurrence of breast cancer (BC) leads to an increased risk of metastases and decreased survival. Ipsilateral breast recurrence can occur at the initial tumor bed or in another quadrant of the breast. Depending on tumor patterns and molecular subtypes, the risk and time to onset of metastatic recurrence differs. HER2-positive and triple-negative (TNG) BC have a risk of locoregional relapse between six and eight times than luminal A. Thus, the management of local and locoregional relapses must take into account the prognostic factors for metastatic disease development. It is important to personalize the overall management, including or not systemic treatment according to the metastatic risk. All isolated recurrence cases should be treated with curative intent. Complete surgical resection is recommended whenever possible. Patients who did not receive postoperative irradiation during their initial management should receive full-dose radiotherapy to the chest wall and to the regional lymph nodes if appropriate. Overall, total mastectomy is the “gold standard” among patients who were previously treated by conservative surgery followed by radiation therapy. In terms of systemic therapy, the benefits of additional treatments are not conclusively proven in cases of isolated recurrence. The beneficial role of chemotherapy has been reported in at least one randomized trial, while endocrine therapy and anti-HER2 are common practice. This review will discuss salvage treatment options of local and locoregional recurrences in the new era of BC molecular subtypes.

The nuclear factor-kappa B pathway and response to treatment in breast cancer

The nuclear factor-kappa B (NF-κB) pathway is known to contribute to critical signaling in cancer biology, including breast cancer, through promotion of proliferation, angiogenesis, metastasis, tumor progression, inflammation and cell survival. In this review, in vivo and in vitro studies of the NF-κB pathway in breast cancer are discussed, focusing on DNA damage and the epithelial-mesenchymal transition associated with breast cancer stem cell properties. The relationships between NF-κB signaling and conventional cancer treatments in terms of response to chemo- and radiotherapy will also be discussed. Then contribution and involvement of immune system in the NF-κB pathway will be covered. Furthermore, the future perspective of NF-κB targeting as an innovative strategy to overcome refractory breast cancer, including recent updates on out-receptor activator of NF-κB (RANKing), will be covered.

Response to Radiotherapy After Breast-Conserving Surgery in Different Breast Cancer Subtypes in the Swedish Breast Cancer Group 91 Radiotherapy Randomized Clinical Trial

Purpose To evaluate the effect of adjuvant radiotherapy (RT) after breast conservation surgery in different breast cancer subtypes in a large, randomized clinical trial with long-term follow-up. Patients and Methods Tumor tissue was collected from 1,003 patients with node-negative, stage I and II breast cancer who were randomly assigned in the Swedish Breast Cancer Group 91 Radiotherapy trial between 1991 and 1997 to breast conservation surgery with or without RT. Systemic adjuvant treatment was sparsely used (8%). Subtyping was performed with immunohistochemistry and in situ hybridization on tissue microarrays for 958 tumors. Results RT reduced the cumulative incidence of ipsilateral breast tumor recurrence (IBTR) as a first event within 10 years for luminal A-like tumors (19% v 9%; P = .001), luminal B-like tumors (24% v 8%; P < .001), and triple-negative tumors (21% v 6%; P = .08), but not for human epidermal growth factor receptor 2-positive (luminal and nonluminal) tumors (15% v 19%; P = .6); however, evidence of an overall difference in RT effect between subtypes was weak ( P = .21). RT reduced the rate of death from breast cancer (BCD) for triple-negative tumors (hazard ratio, 0.35; P = .06), but not for other subtypes. Death from any cause was not improved by RT in any subtype. A hypothesized clinical low-risk group did not have a low risk of IBTR without RT, and RT reduced the rate of IBTR as a first event after 10 years (20% v 6%; P = .008), but had no effect on BCD or death from any cause. Conclusion Subtype was not predictive of response to RT, although, in our study, human epidermal growth factor receptor 2-positive tumors seemed to be most radioresistant, whereas triple-negative tumors had the largest effect on BCD. The effect of RT in the presumed low-risk luminal A-like tumors was excellent.

Nanoparticles for live cell microscopy: A surface-enhanced Raman scattering perspective

Surface enhanced Raman scattering (SERS) nanoparticles are an attractive alternative to fluorescent probes for biological labeling because of their photostability and multiplexing capabilities. However, nanoparticle size, shape, and surface properties are known to affect nanoparticle-cell interactions. Other issues such as the formation of a protein corona and antibody multivalency interfere with the labeling properties of nanoparticle-antibody conjugates. Hence, it is important to consider these aspects in order to validate such conjugates for live cell imaging applications. Using SERS nanoparticles that target HER2 and CD44 in breast cancer cells, we demonstrate labeling of fixed cells with high specificity that correlates well with fluorescent labels. However, when labeling live cells to monitor surface biomarker expression and dynamics, the nanoparticles are rapidly uptaken by the cells and become compartmentalized into different cellular regions. This behavior is in stark contrast to that of fluorescent antibody conjugates. This study highlights the impact of nanoparticle internalization and trafficking on the ability to use SERS nanoparticle-antibody conjugates to monitor cell dynamics.

Plumbagin Suppresses the Invasion of HER2-Overexpressing Breast Cancer Cells through Inhibition of IKKα-Mediated NF-κB Activation

HER2-overexpressing breast cancers account for about 30% of breast cancer occurrences and have been correlated with increased tumor aggressiveness and invasiveness. The nuclear factor-κB (NF-κB) is overexpressed in a subset of HER2-positive breast cancers and its upregulation has been associated with the metastatic potential of HER2-overexpressing tumors. The present study aimed at determining the potential of plumbagin, a naturally occurring naphthoquinone, to inhibit the invasion of HER2-overexpressing breast cancer cells and determine the involvement of NF-κB inhibition in plumbagin-mediated cell invasion suppression. In the present research we showed that plumbagin inhibited the transcriptional activity of NF-κB in HER2-positive breast cancer cells. The suppression of NF-κB activation corresponded with the inhibition of NF-κB p65 phosphorylation and downregulation of NF-κB-regulated matrix metalloproteinase 9 (MMP-9) expression. Plumbagin suppressed the invasion of HER2-overexpressing breast cancer cells and the inhibition of cell invasion was associated with the ability of plumbagin to inhibit NF-κB transcriptional activity. The silencing of NF-κB p65 increased the sensitivity of HER2-overexpressing breast cancer cells to plumbagin-induced cell invasion inhibition. NF-κB inhibition was associated with IκB kinase α (IKKα) activity suppression and inhibition of IκBα phosphorylation and degradation. The knockdown of IKKα resulted in increased sensitivity of HER2-positive cells to plumbagin-induced suppression of NF-κB transcriptional activity and expression of MMP-9. In conclusion, plumbagin inhibits the invasion of HER2-overexpressing breast cancer cells through the inhibition of IKKα-mediated NF-κB activation and downregulation of NF-κB-regulated MMP-9 expression.

Hyaluronan-CD44 interaction promotes oncogenic signaling, microRNA functions, chemoresistance, and radiation resistance in cancer stem cells leading to tumor progression

Hyaluronan (HA), a major component of the extracellular matrix (ECM), is enriched in many types of tumors. There is good evidence linking high levels of HA production in human carcinomas to an aggressive phenotype and tumor metastasis. HA is generally bound to CD44 isoforms (so-called CD44s and CD44v3) which are ubiquitous, abundant, and functionally important cell surface receptors. This chapter describes the evidence for HA/CD44v3-mediated activation of the cytoskeleton (e.g., ankyrin and GTPases) and matrix metalloproteinase (MMP) signaling during tumor progression. A special focus is placed on the role of HA-CD44v3 interaction in cancer stem cells (CSCs). Matrix HA is known to be present in CSC niches. Since CD44v3 serves as a CSC marker, it provides an important physical linkage between matrix HA and various transcription factors that regulate tumor cell functions through distinct signaling pathways. CSCs are known to be chemoresistant and/or radiation resistant and to cause cancer relapse. The purpose of this chapter is to review the most current research on the cellular and molecular biology of CSCs. The emphasis will be placed on both CSC niche and matrix HA-induced microRNA signaling plus various CSC functions (e.g., self-renewal, differentiation, and chemoresistance) during cancer progression. Understanding the regulation of CSCs is critically important for designing CSC-specific therapeutic targets to prevent cancer development and progression.

Biological relevance of Hsp90-binding immunophilins in cancer development and treatment

Immunophilins are a family of intracellular receptors for immunosuppressive drugs. Those immunophilins that are related to immunosuppression are the smallest proteins of the family, i.e., FKBP12 and CyPA, whereas the other members of the family have higher molecular weight because the show additional domains to the drug-binding site. Among these extra domains, the TPR-domain is perhaps the most relevant because it permits the interaction of high molecular weight immunophilins with the 90-kDa heat-shock protein, Hsp90. This essential molecular chaperone regulates the biological function of several protein-kinases, oncogenes, protein phosphatases, transcription factors and cofactors . Hsp90-binding immunophilins where first characterized due to their association with steroid receptors. They regulate the cytoplasmic transport and the subcellular localization of these and other Hsp90 client proteins, as well as transcriptional activity, cell proliferation, cell differentiation and apoptosis. Hsp90-binding immunophilins are frequently overexpressed in several types of cancers and play a key role in cell survival. In this article we analyze the most important biological actions of the best characterized Hsp90-binding immunophilins in both steroid receptor function and cancer development and discuss the potential use of these immunophilins for therapeutic purposes as potential targets of specific small molecules.

Mitochondrial MKP1 is a target for therapy-resistant HER2-positive breast cancer cells

The MAPK phosphatase MKP1 (DUSP1) is overexpressed in many human cancers, including chemoresistant and radioresistant breast cancer cells, but its functional contributions in these settings are unclear. Here, we report that after cell irradiation, MKP1 translocates into mitochondria, where it prevents apoptotic induction by limiting accumulation of phosphorylated active forms of the stress kinase JNK. Increased levels of mitochondrial MKP1 after irradiation occurred in the mitochondrial inner membrane space. Notably, cell survival regulated by mitochondrial MKP1 was responsible for conferring radioresistance in HER2-overexpressing breast cancer cells, due to the fact that MKP1 serves as a major downstream effector in the HER2-activated RAF-MEK-ERK pathway. Clinically, we documented MKP1 expression exclusively in HER2-positive breast tumors, relative to normal adjacent tissue from the same patients. MKP1 overexpression was also detected in irradiated HER2-positive breast cancer stem-like cells (HER2(+)/CD44(+)/CD24(-/low)) isolated from a radioresistant breast cancer cell population after long-term radiation treatment. MKP1 silencing reduced clonogenic survival and enhanced radiosensitivity in these stem-like cells. Combined inhibition of MKP1 and HER2 enhanced cell killing in breast cancer. Together, our findings identify a new mechanism of resistance in breast tumors and reveal MKP1 as a novel therapeutic target for radiosensitization.

Profiling global kinome signatures of the radioresistant MCF-7/C6 breast cancer cells using MRM-based targeted proteomics

Ionizing radiation is widely used in cancer therapy; however, cancer cells often develop radioresistance, which compromises the efficacy of cancer radiation therapy. Quantitative assessment of the alteration of the entire kinome in radioresistant cancer cells relative to their radiosensitive counterparts may provide important knowledge to define the mechanism(s) underlying tumor adaptive radioresistance and uncover novel target(s) for effective prevention and treatment of tumor radioresistance. By employing a scheduled multiple-reaction monitoring analysis in conjunction with isotope-coded ATP affinity probes, we assessed the global kinome of radioresistant MCF-7/C6 cells and their parental MCF-7 human breast cancer cells. We rigorously quantified 120 kinases, of which ¹/₃ exhibited significant differences in expression levels or ATP binding affinities. Several kinases involved in cell cycle progression and DNA damage response were found to be overexpressed or hyperactivated, including checkpoint kinase 1 (CHK1), cyclin-dependent kinases 1 and 2 (CDK1 and CDK2), and the catalytic subunit of DNA-dependent protein kinase. The elevated expression of CHK1, CDK1, and CDK2 in MCF-7/C6 cells was further validated by Western blot analysis. Thus, the altered kinome profile of radioresistant MCF-7/C6 cells suggests the involvement of kinases on cell cycle progression and DNA repair in tumor adaptive radioresistance. The unique kinome profiling results also afforded potential effective targets for resensitizing radioresistant cancer cells and counteracting deleterious effects of ionizing radiation exposure.

Identification of gene expression biomarkers for predicting radiation exposure

A need for more accurate and reliable radiation dosimetry has become increasingly important due to the possibility of a large-scale radiation emergency resulting from terrorism or nuclear accidents. Although traditional approaches provide accurate measurements, such methods usually require tedious effort and at least two days to complete. Therefore, we provide a new method for rapid prediction of radiation exposure. Eleven microarray datasets were classified into two groups based on their radiation doses and utilized as the training samples. For the two groups, Student's t-tests and resampling tests were used to identify biomarkers, and their gene expression ratios were used to develop a prediction model. The performance of the model was evaluated in four independent datasets, and Ingenuity pathway analysis was performed to characterize the associated biological functions. Our meta-analysis identified 29 biomarkers, showing approximately 90% and 80% accuracy in the training and validation samples. Furthermore, the 29 genes significantly participated in the regulation of cell cycle, and 19 of them are regulated by three well-known radiation-modulated transcription factors: TP53, FOXM1 and ERBB2. In conclusion, this study demonstrates a reliable method for identifying biomarkers across independent studies and high and reproducible prediction accuracy was demonstrated in both internal and external datasets.

The role of peroxiredoxin II in chemoresistance of breast cancer cells

Peroxiredoxin (Prx)II belongs to a family of redox-active proteins that use redox-sensitive cysteine in the active site to reduce peroxides. PrxII is induced by various oxidative stimuli and plays an important protective role against oxidative radical damage by reactive oxygen species. PrxII expression levels are correlated with resistance to radiation therapy or certain anti-cancer drugs in radioresistant breast cancer cells, glioblastomas, and head and neck cancer cells as well as in tissue isolated from head and neck patients who do not respond to radiation therapy. Small interfering RNA (siRNA) that inhibits the PrxII gene expression has been shown to partially reverse the radioresistant phenotype in radiation resistant breast cancer cells and sensitizes glioma cells to oxidative stress, highlighting the potential clinical importance of PrxII in radiation resistance in cancer. This article focuses on the role that PrxII may play in chemoresistant breast cancer cells.

Inverse prognostic impact of ErbB2 mRNA and protein expression level in tumors of soft tissue sarcoma patients

BACKGROUND

Human epidermal growth factor receptor 2 (ErbB2) is overexpressed in a variety of human malignancies. Moreover, ErbB2 has been reported to influence cancer patient survival and progression of different tumor entities. However, information regarding the prognostic impact of ErbB2 in soft tissue sarcoma (STS) patients is limited and conflicting.

MATERIAL AND METHODS

ErbB2 mRNA and protein levels were defined by quantitative real-time PCR and enzyme-linked immunosorbent assay (ELISA), and the prognostic impact of ErbB2 mRNA and protein levels in tumor tissue of 124 soft tissue sarcoma patients were investigated.

RESULTS

The median ErbB2 mRNA expression level in tumor tissue was decreased 3.9-fold compared to non-neoplastic surrounding tissue (p = 0.001). Furthermore, an increased ErbB2 mRNA expression level was associated with an improved tumor-specific survival (p = 0.01, log rank test). Multivariate Cox's proportional hazard regression analyses revealed an increased ErbB2 mRNA expression level as an independent favorable prognostic factor for tumor-specific survival of STS patients (n = 124; RR = 3.0; 95 % CI = 1.6-5.7; p < 0.001). In addition, multivariate Cox's proportional hazard regression analyses showed that an increased ErbB2 protein expression level correlated with poorer recurrence-free survival of STS patients (n = 47; RR = 9.9; 95 % CI = 1.7-59.7; p = 0.012), in particular for STS patients who received postoperative radiotherapy (n = 27; RR = 17.9; 95 % CI = 1.3-247.7; p = 0.031).

CONCLUSION

This study suggests an inverse prognostic value of ErbB2 mRNA and protein expression level.

[Locoregional breast radiotherapy and concurrent treatment with trastuzumab]

The overexpression of the Human Epidermal Growth Factor Receptor 2 (HER2) is observed in 15% of breast cancers and associated with poor prognosis in terms of overall survival. Trastuzumab is an anti-HER2 targeted therapy, leading to a specific inhibition of the molecular mechanisms triggered by this receptor. In an adjuvant setting, trastuzumab and radiotherapy have each proved their oncologic efficacy in the management of the breast tumours presenting this molecular profile. However, both treatments expose to an increased risk of toxicities, particularly cardiovascular ones. Moreover, the radiosensitizing effect of trastuzumab has been proved in vitro and in vivo. Hence, in clinical practice, the benefit/risk ratio of a concurrent treatment remains to be defined. This literature review has for purposes to describe the rationale making conceivable the administration of trastuzumab concurrently with locoregional breast radiotherapy, and to remind the results of the clinical studies having assessed this therapeutic association.

Breast cancer adaptive resistance: HER2 and cancer stem cell repopulation in a heterogeneous tumor society

Purpose

The lethal effects of cancer are associated with the enhanced tumor aggressiveness in recurrent and metastatic lesions that show resistant phenotype to anti-cancer therapy, a major barrier to improving overall survival of cancer patients. The presence of heterogeneous populations of cancer cells within a specific tumor including the tumor-initiating cells or so-called cancer stem cells (CSCs) has linked the acquired resistance (AR, or adaptive resistance). Herein, we discuss the CSC-mediated tumor repopulation in AR of breast cancer in this review.

Methods

We emphasize a dynamic feature of gene induction in tumor cells that undergo long-term treatment, and describe a specific HER2-NF-κB-HER2 pro-survival pathway that can be initiated in breast CSCs upon radiation therapy.

Results

Elucidation of HER2-induced pro-survival networks, specifically the force driving tumor repopulation due to radioresistant CSCs during anticancer therapies, will have a significant impact on the generation of new diagnostic and therapeutic targets to control of recurrent and metastatic breast tumors.

Caveolin-1 is involved in radiation-induced ERBB2 nuclear transport in breast cancer cells

This study examined the radiation-induced ERBB2 nuclear transport in the BT474 breast cancer cell line and the relationship between caveolin-1 and radiation-induced ERBB2 nuclear transport. The BT474 cells were treated with herceptin (200 nmol/L), PP2 (a caveolin-1 inhibitor, 100 nmol/L) and irradiation combined or alone. Confocal microscopy was used to observe the nuclear import of ERBB2 and caveolin-1 after irradiation. Western blotting was employed to detect the expression of ERBB2, caveolin-1 and DNA-PKcs after irradiation, and immunoprecipitation to identify the ERBB2 and caveolin-1 complex before perinuclear ERBB2 localization. Confocal microscopy showed the transport of ERBB2 and caveolin-1 from the cell membrane to the nucleus 15 min after irradiation and the proteins accumulated at the perinuclear region within 45 min. Western blotting revealed that the expression levels of ERBB2, caveolin-1 and DNA-PKcs were increased after irradiation and reached a peak 45 min later. Both herceptin and PP2 treatments were found to decrease ERBB2 expression. An immune complex composed of ERBB2 and caveolin-1 was found in the herceptin group after irradiation. It was concluded that after irradiation, ERBB2 may be transported from the cell membrane to the nucleus and activate DNA-PKcs to trigger DNA double-strand break (DSB) repair; caveolin-1 may participate in this process. Treatments involving the downregulation of caveolin-1 may increase the radiosensitization of breast cancer cells.

Zoledronic acid significantly enhances radiation‑induced apoptosis against human fibrosarcoma cells by inhibiting radioadaptive signaling

Zoledronic acid (ZOL), a third-generation bisphosphonate, inhibits bone resorption, as well as exhibiting direct antitumor activity. To date, however, the combined effects of ZOL and ionizing radiation (IR) have not been assessed in patients with soft tissue sarcoma. We have, therefore, assessed the combined effects of ZOL and IR in fibrosarcoma cells. HT1080 fibrosarcoma cells were treated with ZOL and/or IR, together or sequentially and the antitumor effects were assessed. We found that ZOL significantly enhanced IR-induced apoptosis, especially when cells were treated with ZOL followed by IR. We, therefore, assessed the detailed mechanism of sequential treatment with ZOL and IR. Cells in G2 and M phases, the most radiosensitive phases of the cell cycle, were not increased by low concentrations of ZOL. However, the levels of expression of Akt, ERK1/2 and NF-κB proteins, all of which are related to radioadaptive resistance, were increased within a short time after irradiation with 3 Gy, and this expression was inhibited by a low concentration of ZOL, which blocked the prenylation of small GTPases. This sequential treatment also increased the generation of reactive oxygen species (ROS). These results suggest that the combination of ZOL with IR may be beneficial in treating patients with soft tissue sarcoma.

CyclinB1/Cdk1 phosphorylates mitochondrial antioxidant MnSOD in cell adaptive response to radiation stress

Manganese superoxide dismutase (MnSOD), a major antioxidant enzyme within the mitochondria, is responsible for the detoxification of free radicals generated by cellular metabolism and environmental/therapeutic irradiation. Cell cycle-dependent kinase Cdk1, along with its regulatory partner CyclinB1, plays important roles in the regulation of cell cycle progression as well as in genotoxic stress response. Herein, we identified the presence of the minimal Cdk1 phosphorylation consensus sequence ([S/T]-P; Ser106) in human MnSOD, suggesting Cdk1 as a potential upstream kinase of MnSOD. A substantial amount of CyclinB1/Cdk1 was found to localize in the mitochondrion upon irradiation. The enhanced Cdk1/MnSOD interaction and MnSOD phosphorylation were detected in both the irradiated human cells and mouse tissues. We report that CyclinB1/Cdk1 can regulate MnSOD through reversible Ser106 phosphorylation, both in vivo and in vitro. The CyclinB1/Cdk1-mediated MnSOD Ser106 resulted in increased MnSOD activity and stability, along with improved mitochondrial function and cellular resistance to radiation-induced apoptosis. These results demonstrate a unique pro-survival mechanism by which cells enhance the survival via CyclinB1/Cdk1-mediated MnSOD activation under genotoxic stress conditions.

Overrepresentation of transcription factor families in the genesets underlying breast cancer subtypes

Background

The human genome contains a large amount of cis-regulatory DNA elements responsible for directing both spatial and temporal gene-expression patterns. Previous studies have shown that based on their mRNA expression breast tumors could be divided into five subgroups (Luminal A, Luminal B, Basal, ErbB2⁺ and Normal-like), each with a distinct molecular portrait. Whole genome gene expression analysis of independent sets of breast tumors reveals repeatedly the robustness of this classification. Furthermore, breast tumors carrying a TP53 mutation show a distinct gene expression profile, which is in strong association to the distinct molecular portraits. The mRNA expression of 552 genes, which varied considerably among the different tumors, but little between two samples of the same tumor, has been shown to be sufficient to separate these tumor subgroups.

Results

We analyzed in silico the transcriptional regulation of genes defining the subgroups at 3 different levels: 1. We studied the pathways in which the genes distinguishing the subgroups of breast cancer may be jointly involved including upstream regulators (1^st and 2^nd level of regulation) as well as downstream targets of these genes. 2. Then we analyzed the promoter areas of these genes (−500 bp tp +100 bp relative to the transcription start site) for canonical transcription binding sites using Genomatix. 3. We looked for the actual expression levels of the identified TF and how they correlate with the overrepresentation of their TF binding sites in the separate groups. We report that promoter composition of the genes that most strongly predict the patient subgroups is distinct. The class-predictive genes showed a clearly different degree of overrepresentation of transcription factor families in their promoter sequences.

Conclusion

The study suggests that transcription factors responsible for the observed expression pattern in breast cancers may lead us to important biological pathways.

SV40 T/t-common polypeptide enhances the sensitivity of HER2-overexpressing human cancer cells to anticancer drugs cisplatin and doxorubicin

HER2-overexpressing cancer cells are resistant to cisplatin (CDDP) and doxorubicin (DXR). Here we report that SV40 T/t-common polypeptide could specifically sensitize HER2-overexpressing cancer cells to CDDP and DXR and specifically enhance CDDP- or DXR-induced apoptosis in these cells. This activity of T/t-common may be attributed to its ability to inhibit Bcl-2 and Bcl-XL and to suppress ERK activity in CDDP- or DXR-treated HER2-overexpressing cancer cells. T/t-common could enhance the antitumor activity of DXR on HER2-overexpressing ovarian tumor in NOD/SCID mice, suggesting that combination therapy using T/t-common and chemotherapeutic agents may provide a new approach for treating HER2-overexpressing cancers.

Carbon-ion-induced activation of the NF-κB pathway

Carbon-ion cancer therapy offers several physical and radiobiological advantages over conventional photon cancer therapy. The molecular mechanisms that determine cellular outcome, including the activation of transcription factors and the alteration of gene expression profiles, after carbon-ion exposure are still under investigation. We have previously shown that argon ions (LET 272 keV/µm) had a much higher potential to activate the transcription factor nuclear factor κB (NF-κB) than X rays. NF-κB is involved in the regulation of cellular survival, mostly by antiapoptosis and cell cycle-regulating target genes, which are important in the resistance of cancer cells to radiotherapy. Therefore, activation of the NF-κB pathway by accelerated carbon ions (LET 33 and 73 keV/µm) was examined. For comparison, cells were exposed to 150 kV X rays and to accelerated carbon ions. NF-κB-dependent gene induction after exposure was detected in stably transfected human 293 reporter cells. Carbon ions and X rays had a comparable potential to activate NF-κB in human cells, indicating a comparable usefulness of pharmacological NF-κB inhibition during photon and carbon-ion radiotherapy.

The receptor tyrosine kinase FGFR4 negatively regulates NF-kappaB signaling

BACKGROUND

NFκB signaling is of paramount importance in the regulation of apoptosis, proliferation, and inflammatory responses during human development and homeostasis, as well as in many human cancers. Receptor Tyrosine Kinases (RTKs), including the Fibroblast Growth Factor Receptors (FGFRs) are also important in development and disease. However, a direct relationship between growth factor signaling pathways and NFκB activation has not been previously described, although FGFs have been known to antagonize TNFα-induced apoptosis.

METHODOLOGY/PRINCIPAL FINDINGS

Here, we demonstrate an interaction between FGFR4 and IKKβ (Inhibitor of NFκB Kinase β subunit), an essential component in the NFκB pathway. This novel interaction was identified utilizing a yeast two-hybrid screen [1] and confirmed by coimmunoprecipitation and mass spectrometry analysis. We demonstrate tyrosine phosphorylation of IKKβ in the presence of activated FGFR4, but not kinase-dead FGFR4. Following stimulation by TNFα (Tumor Necrosis Factor α) to activate NFκB pathways, FGFR4 activation results in significant inhibition of NFκB signaling as measured by decreased nuclear NFκB localization, by reduced NFκB transcriptional activation in electophoretic mobility shift assays, and by inhibition of IKKβ kinase activity towards the substrate GST-IκBα in in vitro assays. FGF19 stimulation of endogenous FGFR4 in TNFα-treated DU145 prostate cancer cells also leads to a decrease in IKKβ activity, concomitant reduction in NFκB nuclear localization, and reduced apoptosis. Microarray analysis demonstrates that FGF19 + TNFα treatment of DU145 cells, in comparison with TNFα alone, favors proliferative genes while downregulating genes involved in apoptotic responses and NFκB signaling.

CONCLUSIONS/SIGNIFICANCE

These results identify a compelling link between FGFR4 signaling and the NFκB pathway, and reveal that FGFR4 activation leads to a negative effect on NFκB signaling including an inhibitory effect on proapoptotic signaling. We anticipate that this interaction between an RTK and a component of NFκB signaling will not be limited to FGFR4 alone.