Involvement of maternal embryonic leucine zipper kinase (MELK) in mammary carcinogenesis through interaction with Bcl-G, a pro-apoptotic member of the Bcl-2 family

INTRODUCTION: Cancer therapies directed at specific molecular targets in signaling pathways of cancer cells, such as tamoxifen, aromatase inhibitors and trastuzumab, have proven useful for treatment of advanced breast cancers. However, increased risk of endometrial cancer with long-term tamoxifen administration and of bone fracture due to osteoporosis in postmenopausal women undergoing aromatase inhibitor therapy are recognized side effects. These side effects as well as drug resistance make it necessary to search for novel molecular targets for drugs on the basis of well-characterized mechanisms of action. METHODS: Using accurate genome-wide expression profiles of breast cancers, we found maternal embryonic leucine-zipper kinase (MELK) to be significantly overexpressed in the great majority of breast cancer cells. To assess whether MELK has a role in mammary carcinogenesis, we knocked down the expression of endogenous MELK in breast cancer cell lines using mammalian vector-based RNA interference. Furthermore, we identified a long isoform of Bcl-G (Bcl-G(L)), a pro-apoptotic member of the Bcl-2 family, as a possible substrate for MELK by pull-down assay with recombinant wild-type and kinase-dead MELK. Finally, we performed TUNEL assays and FACS analysis, measuring proportions of apoptotic cells, to investigate whether MELK is involved in the apoptosis cascade through the Bcl-G(L)-related pathway. RESULTS: Northern blot analyses on multiple human tissues and cancer cell lines demonstrated that MELK was overexpressed at a significantly high level in a great majority of breast cancers and cell lines, but was not expressed in normal vital organs (heart, liver, lung and kidney). Suppression of MELK expression by small interfering RNA significantly inhibited growth of human breast cancer cells. We also found that MELK physically interacted with Bcl-G(L )through its amino-terminal region. Immunocomplex kinase assay showed that Bcl-G(L )was specifically phosphorylated by MELK in vitro. TUNEL assays and FACS analysis revealed that overexpression of wild-type MELK suppressed Bcl-G(L)-induced apoptosis, while that of D150A-MELK did not. CONCLUSION: Our findings suggest that the kinase activity of MELK is likely to affect mammary carcinogenesis through inhibition of the pro-apoptotic function of Bcl-G(L). The kinase activity of MELK could be a promising molecular target for development of therapy for patients with breast cancers

Activation of an Estrogen/ Estrogen Receptor Signaling by BIG3 Through Its Inhibitory Effect on Nuclear Transport of PHB2/REA in Breast Cancer

Breast cancer is known to be a hormone-dependent disease, and estrogens through an interaction with estrogen receptor (ER) enhance the proliferative and metastatic activity of breast tumor cells. Here we show a critical role of transactivation of BIG3, brefeldin A-inhibited guanine nucleotide-exchange protein 3, in activation of the estrogen/ER signaling in breast cancer cells. Knocking-down of BIG3 expression with small-interfering RNA (siRNA) drastically suppressed the growth of breast cancer cells. Subsequent co-immunoprecipitation and immunoblotting assays revealed an interaction of BIG3 with prohibitin 2/repressor of estrogen receptor activity (PHB2/REA). When BIG3 was absent, stimulation of estradiol caused the translocation of PHB2/REA to the nucleus, enhanced the interaction of PHB2/REA and ER[alpha], and resulted in suppression of the ER[alpha]; transcriptional activity. On the other hand, when BIG3 was present, BIG3 trapped PHB2/REA in cytoplasm and inhibited its nuclear translocation, and caused enhancement of ER[alpha]; transcriptional activity. Our results imply that BIG3 overexpression is one of the important mechanisms causing the activation of the estrogen/ER[alpha]; signaling pathway in the hormone-related growth of breast cancer cells

Short-and Midterm Outcomes of Laparoscopy Assisted Colectomy for Colon and Rectosigmoid Cancer

Background: Laparoscopy-assisted colectomy (LAC) has gained acceptance for the treatment of colon cancer. Objective: To evaluate the use and outcomes of LAC. Patients: Patients who underwent LAC (n = 176) for colon and rectosigmoid cancer (2001-2008). Results: There were 97 men (55.1%) and 79 women(44.9%), whose median age was 67.5 years (range, 33-99 years). The median operating time for patients who underwent LAC was 216 minutes (range, 70-440). The median blood loss was 60 ml (range 10-610 ml). Intra- and postoperative complicacomplications occurred in 3 (1.7%) and 16 patients (9.1%), respectively. The morbidity rate of patients was 0%. The overall survival rates for 3 years were 100.0%, 97.5%, 95.9%, 90.1% and 77.9% for stages 0,Ⅰ,Ⅱ,Ⅲa and Ⅲb, respectively. The relapse-free survival rates for 3 years were 100.0%, 100.0%, 90.1%, 65.7% and 62.3% for stages 0, Ⅰ,Ⅱ,Ⅲa and Ⅲb, respectively. Conclusion: This study confirmed the favorable short-and midterm operative results in patients who underwent LAC

Surgical benefits of liver hanging maneuver for hepatectomy of huge liver tumor

In hepatic surgery, it is very important to control bleeding during liver resection. However, in hepatectomy for a huge liver tumor it is often difficult to reduce bleeding volume and maintain an excellent surgical view. The anterior pproach, which is hepatectomy done using the liver hanging maneuver, has beneficial effects reducing bleeding volume and preventing scattering of cancer cells from huge liver tumors. W e investigated the surgical benefits of the liver anging maneuver during hepatectomy for huge liver tumors in our department.

Vascular endothelial growth factor 165b expression in stromal cells and colorectal cancer

AIM: To characterize the implications of vascular endothelial growth factor (VEGF)-A in stromal cells and colorectal cancer and the expression of VEGF-A splice variants