Suk Young Lee

BMP-2 induces motility and invasiveness by promoting colon cancer stemness through STAT3 activation

Bone morphogenetic proteins (BMPs) have been involved in metastatic progression and tumorigenesis of many cancer types. However, it remains unclear how BMP-2 contributes to the initiation and development of these cancers. Here, we investigated the role of BMP-2 in colon cancer stem cell (CSC) development from colon cancer cells. We also determined the effects of BMP-2 on CSC development and epithelial-mesenchymal transition (EMT) in human colon cancer cell lines HCT-116 and SW620. We found that BMP-2 enhanced sphere formation of colon cancer cells without serum. Also, BMP-2-induced spheres displayed up-regulation of stemness markers (CD133+ and EpCAM+) and increased drug resistance, hallmarks of CSCs. Importantly, expression of EMT activators p-Smad1/5 and Snail and N-cadherin was increased in the spheres’ cells, indicating that BMP-2 signaling might result in CSC self-renewal and EMT. Furthermore, siRNA-mediated knockdown of signal transducer and activator of transcription 3 (STAT3) in HCT-116 cells reversed BMP-2-induced EMT and stem cell formation. Taken together, our results suggest that the BMP-2 induced STAT3-mediated induction of colon cancer cell metastasis requires an EMT and/or changes in CSC markers.

Changing strategies for target therapy in gastric cancer

In spite of a worldwide decrease in the incidence of gastric cancer, this malignancy still remains one of the leading causes of cancer mortality. Great efforts have been made to improve treatment outcomes in patients with metastatic gastric cancer, and the introduction of trastuzumab has greatly improved the overall survival. The trastuzumab treatment took its first step in opening the era of molecular targeted therapy, however several issues still need to be resolved to increase the efficacy of targeted therapy. Firstly, many patients with metastatic gastric cancer who receive trastuzumab in combination with chemotherapeutic agents develop resistance to the targeted therapy. Secondly, many clinical trials testing novel molecular targeted agents with demonstrated efficacy in other malignancies have failed to show benefit in patients with metastatic gastric cancer, suggesting the importance of the selection of appropriate indications according to molecular characteristics in application of targeted agents. Herein, we review the molecular targeted agents currently approved and in use, and clinical trials in patients with metastatic gastric cancer, and demonstrate the limitations and future direction in treatment of advanced gastric cancer.

Case Report of Pulmonary Sarcoidosis Suspected to be Pulmonary Metastasis in a Patient with Breast Cancer

Standard endocrine therapy and chemotherapy can induce long-term remission in breast cancer patients; however, breast cancer can recur at any site. Pulmonary nodules with lymphadenopathy in advanced cancer patients are likely to be assumed as metastases. A 44-year-old woman with a history of breast cancer was presented to our institution with abnormal findings on 18-fluorodeoxyglucose positron emission tomography imaging, which suggested lung metastasis. She had previously been diagnosed with breast cancer (T1N2M0, Stage IIIa, intraductal carcinoma, triple negative cancer). Histological analysis of the mediastinal lymph node biopsy demonstrated sarcoidosis, showing a chronic, non-caseating, granulomatous inflammation. Our case highlights the need for non-malignant diagnoses in those with prior malignancies, and the need for histological evaluations in the event of first recurrence following potentially curative therapy.

Prognostic Factors and Skeletal-Related Events in Patients with Small Cell Lung Cancer with Bone Metastases at the Time of Diagnosis

Background/Objective: The aim of this study was to evaluate the characteristics and prognostic factors of small cell lung cancer (SCLC) with bone metastases. We also investigated the characteristics and predictive factors of skeletal-related events (SREs) in these patients. Materials and Methods: Sixty-one patients who were first diagnosed with SCLC with bone metastases at our institution were included in this retrospective analysis. Results: The overall survival (OS) of patients with bone metastases was shorter than that of patients without bone metastases (4.13 vs. 6.17 months, p = 0.015). Poor Eastern Cooperative Oncology Group (ECOG) performance status (PS; ≥2) and higher serum alkaline phosphatase (ALP; above upper normal limit × 2) were independent poor prognostic factors (p = 0.027 for ECOG PS, p = 0.002 for ALP). More than 1 SRE occurred in 21 patients (34.4%). Cervical spine metastasis, thoracic spine metastasis, pelvic bone metastasis, more than 5 bone metastatic regions and higher serum lactate dehydrogenase were correlated with the occurrence of SREs. Thoracic spinal metastasis was a strong predictive factor for the occurrence of SREs (odds ratio = 5.475; 95% CI: 1.080-27.755). Conclusion: Our study demonstrates the poor prognosis of SCLC patients with bone metastases. Physicians should treat SCLC patients with bone metastases with caution.

Advances of Targeted Therapy in Treatment of Unresectable Metastatic Colorectal Cancer

Despite being one of the most frequently diagnosed cancers worldwide, prognosis of metastatic colorectal cancer (CRC) was poor. Development and introduction of biologic agents in treatment of patients with metastatic CRC have brought improved outcomes. Monoclonal antibodies directing epidermal growth factor receptors and vascular endothelial growth factor are main biologic agents currently used in treatment of metastatic CRC. Encouraged by results from many clinical trials demonstrating efficacy of those monoclonal antibodies, the combination therapy with those targeted agents and conventional chemotherapeutic agents has been established as the standard therapy for patients with metastatic CRC. However, emergency of resistance to those target agents has limited the efficacy of treatment, and strategies to overcome the resistance are now being investigated by newly developed biological techniques clarifying how to acquire resistance. Here, we introduce mechanisms of action of the biologic agents currently used for treatment of metastatic CRC and several landmark historical clinical studies which have changed the main stream of treatment. The mechanism of resistance to those agents, one of serious problems in treatment metastatic CRC, and ongoing clinical trials to overcome the limitations and improve treatment outcomes will also be presented in this review.

Metformin enhances TRAIL-induced apoptosis by Mcl-1 degradation via Mule in colorectal cancer cells

Metformin is an anti-diabetic drug with a promising anti-cancer potential. In this study, we show that subtoxic doses of metformin effectively sensitize human colorectal cancer (CRC) cells to tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), which induces apoptosis. Metformin alone did not induce apoptosis, but significantly potentiated TRAIL-induced apoptosis in CRC cells. CRC cells treated with metformin and TRAIL showed activation of the intrinsic and extrinsic pathways of caspase activation. We attempted to elucidate the underlying mechanism, and found that metformin significantly reduced the protein levels of myeloid cell leukemia 1 (Mcl-1) in CRC cells and, the overexpression of Mcl-1 inhibited cell death induced by metformin and/or TRAIL. Further experiments revealed that metformin did not affect mRNA levels, but increased proteasomal degradation and protein stability of Mcl-1. Knockdown of Mule triggered a significant decrease of Mcl-1 polyubiquitination. Metformin caused the dissociation of Noxa from Mcl-1, which allowed the binding of the BH3-containing ubiquitin ligase Mule followed by Mcl-1ubiquitination and degradation. The metformin-induced degradation of Mcl-1 required E3 ligase Mule, which is responsible for the polyubiquitination of Mcl-1. Our study is the first report indicating that metformin enhances TRAIL-induced apoptosis through Noxa and favors the interaction between Mcl-1 and Mule, which consequently affects Mcl-1 ubiquitination.

The Inositide Signaling Pathway As a Target for Treating Gastric Cancer and Colorectal Cancer

Gastric cancer and colorectal cancer are the leading cause of cancer mortality and have a dismal prognosis. The introduction of biological agents to treat these cancers has resulted in improved outcomes, and combination chemotherapy with targeted agents and conventional chemotherapeutic agents is regarded as standard therapy. Additional newly clarified mechanisms of oncogenesis and resistance to targeted agents require the development of new biologic agents. Aberrant activation of the inositide signaling pathway by a loss of function PTEN mutation or gain of function mutation/amplification of PIK3CA is an oncogenic mechanism in gastric cancer and colorectal cancer. Clinical trials with biologic agents that target the inositide signaling pathway are being performed to further improve treatment outcomes of patients with advanced gastric cancer and metastatic colorectal cancer (CRC). In this review we summarize the inositide signaling pathway, the targeted agents that inhibit abnormal activation of this signaling pathway and the clinical trials currently being performed in patients with advanced or metastatic gastric cancer and metastatic CRC using these targeted agents.

BK virus encephalitis without concurrent hemorrhagic cystitis in an allogeneic hematopoietic stem cell transplant recipient

TO THE EDITOR: The BK virus (BKV) is a human polyomavirus of the Papovaviridae family and causes clinical disease mainly in immunocompromised hosts such as patients infected with human immunodeficiency virus or transplant recipients [1]. Only a few cases of BKV encephalitis have been reported in hematopoietic stem cell (HSC) transplant recipients, with the majority of cases presenting with concurrent hemorrhagic cystitis [2-4]. In this paper, we report a patient with BKV encephalitis without concurrent hemorrhagic cystitis who received allogeneic stem cell transplantation from a matched sibling donor for treatment of a second relapse of diffuse large B cell lymphoma following autologous HSC transplantation (HSCT).

Genipin suppresses colorectal cancer cells by inhibiting the Sonic Hedgehog pathway

Genipin, a major component of Gardenia jasminoides Ellis fruit, has been shown to inhibit the growth of gastric, prostate, and breast cancers. However, the anti-proliferative activity of genipin in colorectal cancer (CRC) has not been characterized. Herein, we demonstrated that genipin inhibits the proliferation of CRC cells and that genipin suppressed the Hedgehog pathway. Further investigation showed that p53 and NOXA protein levels were increased during inhibition of Hedgehog pathway-mediated apoptosis in CRC cells. We also showed that p53 modulated the expression of NOXA during genipin-induced apoptosis, and suppression via SMO also played a role in this process. Subsequently, GLI1 was ubiquitinated by the E3 ligase PCAF. In a xenograft tumor model, genipin suppressed tumor growth, which was also associated with Hedgehog inactivation. Taken together, these results suggest that genipin induces apoptosis through the Hedgehog signaling pathway by suppressing p53. These findings reveal a novel regulatory mechanism involving Hedgehog/p53/NOXA signaling in the modulation of CRC cell apoptosis and tumor-forming defects.

Cyclopamine sensitizes TRAIL-resistant gastric cancer cells to TRAIL-induced apoptosis via endoplasmic reticulum stress-mediated increase of death receptor 5 and survivin degradation

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is one of the most effective cancer treatments owing to its ability to selectively kill cancer cells, without affecting normal cells. However, it has been reported that several gastric cancer cells show resistance to TRAIL because of a scarcity of death receptor 5 (DR5) expressed on the cell surface. In this study, we show that cyclopamine sensitizes gastric cancer cells to TRAIL-induced apoptosis by elevating the expression of DR5. Interestingly, survivin hampers the existence of DR5 protein under normal conditions and cyclopamine decreases the expression of survivin, thus acting as a TRAIL sensitizer. Mechanistically, cyclopamine induces endoplasmic reticulum (ER) stress via reactive oxygen species (ROS) and CHOP, the last protein of the ER stress pathway and it regulates the proteasome degradation of survivin. Taken together, our results indicate that cyclopamine can be used for combination therapy in TRAIL-resistant gastric cancer cells.