High serum proteinase-3 levels predict poor progression-free survival and lower efficacy of bevacizumab in metastatic colorectal cancer.

BACKGROUND: To improve the prognosis of patients with metastatic colorectal cancer (mCRC), investigating predictive biomarkers of their prognosis and chemotherapeutic responsiveness is necessary. This study aimed to analyze the clinical significance of serum proteinase-3 (PRTN3) as a predictor for prognosis and chemosensitivity, especially to bevacizumab therapy, in mCRC. METHODS: This single-center retrospective observational study enrolled 79 patients with mCRC in our hospital and 353 patients with colorectal cancer in the TCGA database. Preoperative serum PRTN3 levels were measured using an enzyme-linked immunosorbent assay. The clinicopathological characteristics and prognosis according to serum PRTN3 levels were then evaluated. PRTN3 expression in tumor and stromal cells was evaluated immunohistochemically. The impact of PRTN3 levels on angiogenesis and bevacizumab sensitivity was evaluated using the tube formation assay. RESULTS: Serum PRTN3 levels were an independent poor prognostic factor for progression-free survival (PFS) (hazard ratio, 2.082; 95% confidence interval, 1.118-3.647; P=0.010) in patients with mCRC. Similarly, prognostic analysis with TCGA data sets showed poorer overall survival in patients with PRTN3 expression than that in patients without PRTN3 expression, especially in patients with stage IV. Immunohistochemical analysis of resected specimens revealed that stromal neutrophils expressed PRTN3, and their expression level was significantly correlated with serum PRTN3 levels. Interestingly, the effectiveness of first-line chemotherapy was significantly poorer in the high serum PRTN3 level group. High serum PRTN3 was significantly associated with poor PFS (hazard ratio, 3.027; 95% confidence interval, 1.175-7.793; P=0.0161) in patients treated with bevacizumab, an anti-angiogenic inhibitor. The tube formation assay revealed that PRTN3 administration notably augmented angiogenesis while simultaneously attenuating the anti-angiogenic influence exerted by bevacizumab therapy. CONCLUSIONS: Serum PRTN3 levels could be a novel predictive biomarker of PFS of first-line chemotherapy, especially for bevacizumab therapy, in patients with mCRC.

Fyn-Mediated Paxillin Tyrosine 31 Phosphorylation Regulates Migration and Invasion of Breast Cancer Cells.

Metastasis is the leading cause of death in breast cancer patients due to the lack of effective therapies. Elevated levels of paxillin expression have been observed in various cancer types, with tyrosine phosphorylation shown to play a critical role in driving cancer cell migration. However, the specific impact of the distinct tyrosine phosphorylation events of paxillin in the progression of breast cancer remains to be fully elucidated. Here, we found that paxillin overexpression in breast cancer tissue is associated with a patient's poor prognosis. Paxillin knockdown inhibited the migration and invasion of breast cancer cells. Furthermore, the phosphorylation of paxillin tyrosine residue 31 (Tyr31) was significantly increased upon the TGF-ß1-induced migration and invasion of breast cancer cells. Inhibiting Fyn activity or silencing Fyn decreases paxillin Tyr31 phosphorylation. The wild-type and constitutively active Fyn directly phosphorylate paxillin Tyr31 in an in vitro system, indicating that Fyn directly phosphorylates paxillin Tyr31. Additionally, the non-phosphorylatable mutant of paxillin at Tyr31 reduces actin stress fiber formation, migration, and invasion of breast cancer cells. Taken together, our results provide direct evidence that Fyn-mediated paxillin Tyr31 phosphorylation is required for breast cancer migration and invasion, suggesting that targeting paxillin Tyr31 phosphorylation could be a potential therapeutic strategy for mitigating breast cancer metastasis.

[A Case of HER2-Positive Advanced Breast Cancer Who Was Able to Start and Continue Chemotherapy Despite Liver Damage Due to Diffuse Liver Metastasis].

49-year-old woman, who diagnosed advanced breast cancer with, ER-positive, HER2-positive, T4bN1M1, Stage Ⅳ. At the time of initial diagnosis, liver damage equivalent to Child-Pugh classification C due to diffuse liver metastasis was observed, but trastuzumab/pertuzumab(HP)and paclitaxel(PTX)adjusted according to liver function were administered every 3 weeks, resulting in rapid improvement of liver function, PR of the primary tumor(90% reduction), PR of the liver metastases(70% reduction), and improvement of tumor markers. Currently, chemotherapy has been switched to docetaxel (DTX)due to peripheral neuropathy caused by PTX, and treatment is continuing. In the case of HER2-positive breast cancer, good disease control may be achieved with aggressive treatment and intervention under dose adjustment and careful systemic management, even in the setting of liver injury.

[Invasive Ductal Carcinoma within a Borderline Malignancy Phyllodes Tumor-A Case Report].

Phyllodes tumors are uncommon breast neoplasms that constitute 1-2% of breast malignancies. Invasive ductal carcinoma in the epithelial component of phyllodes tumor is very rare. When carcinoma is detected within the specimen, the management of treatment changes completely. We report a rare case of invasive ductal carcinoma arising in a giant borderline malignancy phyllodes tumor in a 51-year-old female patient. A painful 20 cm mass was found in her right breast, and a needle biopsy revealed fibroadenoma or benign phyllodes tumor, and a total mastectomy was performed. Pathological results showed that a borderline malignant phyllodes tumor coexisted with invasive ductal carcinoma. We explained that axillary surgery was necessary because invasive cancer was diagnosed after surgery, but the patient requested follow-up using images. Endocrine therapy was performed as postoperative adjuvant therapy, and the follow-up is underway without recurrence.

[Questionnaire Survey of Treatment for Elderly Breast Cancer in Yamaguchi Prefecture].

A questionnaire survey was conducted by 17 doctors from 14 hospitals regarding treating elderly breast cancer in Yamaguchi Prefecture. The survey items are the implementation status of the geriatric assessment(GA)for the elderly, the state at the start of treatment(fit/vulnerable/frail), and the setting of restrictions on the indication of surgery and drug treatment (endocrine therapy/chemotherapy/molecular targeted therapy). Only one institution(6%)was used for GA; the tools used were the G8 and Charlson comorbidity index. Regarding surgical treatment, most facilities did not set restrictions according to age or condition. Endocrine and molecular-targeted therapies(anti-HER drugs)are highly tolerated, and most facilities do not have age restrictions. On the other hand, 40% of the respondents set age restrictions on chemotherapy. Four(24%) therapists said they would limit their age to 70 to 75 if the patient had a frail condition. These results tended to be similar to the reports of NCD-registered elderly breast cancer treatment.

Transcript-targeted analysis reveals isoform alterations and double-hop fusions in breast cancer.

Although transcriptome alteration is an essential driver of carcinogenesis, the effects of chromosomal structural alterations on the cancer transcriptome are not yet fully understood. Short-read transcript sequencing has prevented researchers from directly exploring full-length transcripts, forcing them to focus on individual splice sites. Here, we develop a pipeline for Multi-Sample long-read Transcriptome Assembly (MuSTA), which enables construction of a transcriptome from long-read sequence data. Using the constructed transcriptome as a reference, we analyze RNA extracted from 22 clinical breast cancer specimens. We identify a comprehensive set of subtype-specific and differentially used isoforms, which extended our knowledge of isoform regulation to unannotated isoforms including a short form TNS3. We also find that the exon-intron structure of fusion transcripts depends on their genomic context, and we identify double-hop fusion transcripts that are transcribed from complex structural rearrangements. For example, a double-hop fusion results in aberrant expression of an endogenous retroviral gene, ERVFRD-1, which is normally expressed exclusively in placenta and is thought to protect fetus from maternal rejection; expression is elevated in several TCGA samples with ERVFRD-1 fusions. Our analyses provide direct evidence that full-length transcript sequencing of clinical samples can add to our understanding of cancer biology and genomics in general.

Development of a self-assessment behavioral and psychological symptoms of dementia competency scale for care teams at long-term geriatric care facilities.

Understanding the behavioral and psychological symptoms of dementia (BPSD) is important for caregivers in long-term geriatric care facilities. In this study performed in 43 long-term care facilities, we evaluated the ability of caregivers to recognize BPSD through the development and validation of self-assessment scales. Reliability and validity of the scales were determined using Cronbach's alpha coefficient, the test/retest method, exploratory factor analysis, confirmatory factor analysis, criteria-related validity, and construct validity. We analyzed cross-sectional data from 310 participants. Factor analysis showed a positive correlation for all scale items (rs = .43-.73). Significant correlations arose from the test/retest method (rs = .48-.76). The α coefficient of all items except one was .70 or more, indicating sufficient reliability. Criteria-related validity (rs = .43-.73) and construct validity (rs = .13-.52) revealed a positive correlation. The BPSD Team Care Self-Assessment Scale is reliable and could ensure BPSD competency in caregivers.

[A Case of Anastomotic Recurrence of Rectal Cancer Treated by Laparoscopic Total Pelvic Exenteration after Neoadjuvant Chemoradiation].

Patient is 69-year-old man, who underwent a high anterior resection with laparoscopic support for rectal cancer. The patient was diagnosed with anastomotic recurrent rectal cancer after 14 months after surgery. The pelvic MRI scan showed invasion of the prostate and seminal vesicles, so NACRT was performed. Tumors were found to have decreased in size, although there was still some residual invasion of the prostate and seminal vesicle. Laparoscopic total pelvic exenteration (Lap-TPE), and combined excision of the anal elevator muscle and bladder were performed. Preoperative diagnosis was ycT4b, N0, M0, ycStage Ⅱ, and pathological diagnosis was pT4b (prostate and seminal vesicles), INF b, Ly2, v2, Pn1b, pPM0, pDM0, pRM0, and pN0. Laparoscopic surgery allowed to operate safely, with minimal blood loss and a good field of vision. After postoperative adjuvant chemotherapy, lung and liver metastasis appeared after 6 months after surgery, but there was no local recurrence. The patient is treated with chemotherapy, and the metastases are under control. The patient is survive 17 months after Lap-TPE.

Serum LOX-1 is a novel prognostic biomarker of colorectal cancer.

BACKGROUND: Colorectal cancer is the third most common cancer worldwide. If biomarkers can be identified in liquid biopsy, diagnosis and treatment can be optimized even when cancerous tissues are not available. The purpose of this study was to identify proteins from liquid biopsy that would be useful as markers of poor prognosis. METHODS: First, we comprehensively analyzed serum proteins to identify potential biomarkers and focused on serum lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). The relationship between LOX-1 and the prognosis of patients with colorectal cancer has not been reported. Next, we validated this marker using serum samples from 238 patients with colorectal cancer by ELISA and 100 tissue samples by immunohistochemical staining. RESULTS: The optimal cut-off value of serum LOX-1 was 538.7 pg/mL according to time-dependent receiver operating characteristics curve analysis. The overall survival of patients with high levels of serum LOX-1 was significantly poorer than that of individuals with low levels of LOX-1 in the training and test datasets. In multivariate analysis for overall survival, serum LOX-1 was an independent prognostic factor identified in liquid biopsy (hazard ratio = 1.729, p = 0.027). The prognosis of patients with high LOX-1 expression in tumor tissues was significantly poorer than that of individuals with low expression (p =0.047 ). Additionally, inflammatory factors such as white blood cell count, C-reactive protein level, neutrophil/lymphocyte ratio, and monocyte/lymphocyte ratio were significantly higher in the group with high serum LOX-1 levels. CONCLUSIONS: Serum LOX-1 might be a useful biomarker of poor prognosis in colorectal cancer.

[A Case of Local Recurrence in the Reconstructed Breast Three Years after Reconstructive Surgery and Seven Years after Breast Cancer Surgery].

In recent years, breast reconstruction has been increasingly performed in breast cancer surgery with improving the appearance of the breast. We report a case of local breast cancer recurrence after artificial breast reconstruction. The patient was a 52-year-old woman. She had undergone total mastectomy for left breast cancer 11 years ago, and reconstruction with breast implant 3 years ago. She presented to our hospital with the chief complaint of skin redness and induration of the reconstructed breast. A core needle biopsy was performed, and its results showed in the invasive ductal carcinoma. She had an operation of resection of tumor and reconstruction implant. As a result of histopathological diagnosis, it was a local recurrence of breast cancer 11 years ago. After the surgery, she underwent endocrine therapy and there is no recurrence. As the increase in the number of cases of breast reconstruction, the number of recurrences in the reconstructed breast is expected to increase the future. The treatment strategy for cases of local recurrence after breast reconstruction is currently under review, the accumulation of evidence is necessary.

[Investigation of Patients with Stage â £ Breast Cancer Who Underwent Primary Tumor Resection].

We investigated whether primary tumor resection performed at our department for the purpose of local control affects the disease progression of Stage Ⅳ breast cancer. Fifteen patients who underwent primary tumor resection between 2009 and 2017 were investigated. The median age at the time of surgery was 63 years. There were two postoperative deaths(1 at<1 year postoperatively and 1 at<2 years postoperatively). The median postoperative stable disease(SD)period was 11 months overall and was 12 months or longer in 7 patients. SD was attained by all patients with the first drug treatment after primary tumor resection. Patients who tended to have a longer postoperative SD period did not receive preoperative drug treatment, were luminal HER2-positive, and had one metastatic organ. Regardless of surgery timing and reason, there were no cases of rapid postoperative disease progression. In all patients, postoperative local control was satisfactory, and continuation of medical treatment was feasible for distant metastatic tumors. These data signify that primary tumor resection can be considered to treat Stage Ⅳ breast cancer for the purpose of local control.

High secreted protein acidic and rich in cysteine expression in peritumoral fibroblasts predicts better prognosis in patients with resectable gastric cancer.

Secreted protein acidic and rich in cysteine (SPARC) is an extracellular matrix glycoprotein that may serve an important role in epithelial-mesenchymal transition. Recent studies have demonstrated that SPARC status is a prognostic indicator in various cancer types; however, its value remains unclear in gastric cancer (GC). In the present study, the localization and prognostic impact of SPARC expression were evaluated in patients with GC. Immunohistochemical analysis of SPARC expression was performed in 117 surgically resected GC specimens, and the localization of SPARC positive cells, as well as the rassociation between SPARC expression and clinicopathological characteristics were evaluated. High SPARC expression was observed in 47 cases; the glycoprotein was localized in the peritumoral fibroblasts, but was rarely observed in the cytoplasm of cancer cells. Heterogeneity of SPARC expression was observed in 52 cases. High stromal SPARC expression was identified to be an independent predictor of more favorable prognosis (overall survival and recurrence free survival) in all patients (P<0.001). On subgroup analysis, this association remained significant in patients who received adjuvant chemotherapy, but not in patients who did not (P<0.001). Stromal SPARC expression predicts better prognosis in GC patients who underwent curative resection; this appears to be associated with improved response to chemotherapy.

Expression levels of UL16 binding protein 1 and natural killer group 2 member D affect overall survival in patients with gastric cancer following gastrectomy.

UL16 binding protein 1 (ULBP1) expressed on the tumor cell surface binds to the natural killer group 2 member D (NKG2D) receptor presenting on natural killer (NK), cluster of differentiation (CD)8+ T, and γ δ T cells. However, the roles of ULBP1 and NKG2D expression and associated immune responses in gastric cancer are unclear. The present study investigated the associations between ULBP1 and NKG2D expression and clinical outcomes in patients with gastric cancer. The levels of ULBP1 and NKG2D expression were examined in human gastric cancer cell lines and gastric cancer tissues from 98 patients who underwent surgery from 2004 to 2008. MKN-74 cells expressed ULBP1 with ULBP2, -5, or -6. NKG2D was expressed at a higher level following activation of T cells and NK cells. Among the tissue sections positive for NKG2D expression, 6 patients were positive for CD8 and CD56. In all tissues, NKG2D-expressing cells were typically aCD8+ T cells. Patients with NKG2D expression in tumors exhibited significantly longer overall survival (OS) compared with patients without NKG2D expression in tumors (P=0.0217). The longest OS was observed in patients positive for ULBP1 and NKG2D, whereas the shortest OS was observed in patients negative for ULBP1 and NKG2D. The interaction between ULBP1 and NKG2D may improve OS in patients with gastric cancer, and may have applications in immunotherapy for the induction of adaptive immunity in patients with cancer. Additionally, ULBP1 and NKG2D may be useful as prognostic biomarkers in gastric cancer.

Lentinula edodes mycelia extract plus adjuvant chemotherapy for breast cancer patients: Results of a randomized study on host quality of life and immune function improvement.

Anthracycline-based chemotherapies for breast cancer are known to adversely affect patients' quality of life (QOL) and immune function. For that reason, adjuvants that improve those impairments are required. A randomized double-blind study was conducted to evaluate the effectiveness of Lentinula edodes mycelia extract (LEM), which is an oral biological response modifier (BRM) medicine for cancer patients as such an adjuvant. A total of 47 breast cancer patients who were scheduled to receive postoperative adjuvant anthracycline-based chemotherapy, i.e., 5-fluorouracil (5-FU) + cyclophosphamide + epirubicin (FEC regimen), 5-FU + cyclophosphamide + doxorubicin/pirarubicin (FAC regimen), cyclophosphamide + doxorubicin/pirarubicin (AC regimen) and cyclophosphamide + epirubicin (EC regimen), were entered in the study. The patients were randomly divided into either an LEM or a placebo tablet group; the tablets were orally ingested daily over 2 courses of each therapy. In the placebo group, the total scores for QOL were lower on day 8 of the second course of chemotherapy compared with the baseline scores, whereas in the LEM group the scores had not decreased. In the placebo group, the QOL functional well-being score was lower on day 8 after both the first and second courses of chemotherapy compared with the baseline score, but it had not decreased in the LEM group. Evaluation of immunological parameters indicated that an increase in the proportion of regulatory T cells to peripheral blood CD4+ cells tended to be inhibited in the LEM group compared with the placebo group. Oral LEM that was coadministered with anthracycline-based chemotherapies was useful for maintaining patients' QOL and immune function. Thus, LEM appears to be a useful oral adjuvant for patients receiving anthracycline-based chemotherapy.

A phase II, multicenter, single-arm study of tri-weekly low-dose nanoparticle albumin-bound paclitaxel chemotherapy for patients with metastatic or recurrent breast cancer.

BACKGROUND: Nanoparticle albumin-bound (nab)-paclitaxel is a solvent-free formulation of paclitaxel that is bound to albumin and has demonstrated improved progression free survival in previous studies of breast cancer. However, it is difficult to treat Japanese patients with metastatic or recurrent breast cancer with the recommended dose of 260 mg/m2 of (nab)-paclitaxel for more than six cycles due to the occurrence of adverse events. To evaluate the treatment continuity and safety of low-dose nab-paclitaxel, we conducted a phase II study of nab-paclitaxel in patients with metastatic or recurrent breast cancer who had received up to one prior chemotherapy. PATIENTS AND METHODS: Treatment included low doses of 180 mg/m2 nab-paclitaxel that were administered on day 1 of each 3-week cycle to 35 patients. The primary endpoint was the completion rate of six cycles of treatment. RESULTS: A total of 35 eligible patients were enrolled and received a median of eight (range 2-24) cycles of low-dose nab-paclitaxel therapy. The completion rate of six cycles of treatment was 66%. ORR and clinical benefit rate was 23 and 71%, respectively. Median PFS was 6.5 months and median OS was 44 months. Adverse events were relatively mild. Commonly observed grade 3/4 adverse events were neutropenia (46%), leukopenia (9%), and hypertension (3%). No grade 3-4 peripheral sensory neuropathy occurred. CONCLUSION: Treatment with a low dose of nab-paclitaxel once every 3 weeks was tolerable and of acceptable safety and might be beneficial for patients with metastatic or recurrent breast cancer.

[Efficacy and Safety of Everolimus plus Exemetane in Postmenopausal Endocrine-Responsive Metastatic Breast Cancer Patients].

Everolimus and exemestane combination therapy represents a treatment option for estrogen receptor(ER)-positive metastatic breast cancer. We evaluated the efficacy and safety of everolimus and exemestane therapy, retrospectively. After a median follow-up of 10.5 months, the median progression-free survivalin patients was 4.7 months. The clinicalbenefit rate was 27%and the disease controlrate was 64%. The most common all-grade adverse events(AEs)were stomatitis(82%) and non-infectious lung disease(27%). The most commonB3 grade AEs were cellulitis(18%)and hyperglycemia(18%). The AEs reported were mostly grade 1 and 2, and manageable with appropriate intervention. Combination therapy with everolimus and exemestane appears to be a useful addition for ER-positive metastatic breast cancer, with carefulmanage- ment of specific AEs.

Calreticulin is highly expressed in pancreatic cancer stem-like cells.

Cancer stem-like cells (CSLCs) in solid tumors are thought to be resistant to conventional chemotherapy or molecular targeting therapy and to contribute to cancer recurrence and metastasis. In this study, we aimed to identify a biomarker of pancreatic CSLCs (P-CSLCs). A P-CSLC-enriched population was generated from pancreatic cancer cell lines using our previously reported method and its protein expression profile was compared with that of parental cells by 2-D electrophoresis and tandem mass spectrometry. The results indicated that a chaperone protein calreticulin (CRT) was significantly upregulated in P-CSLCs compared to parental cells. Flow cytometry analysis indicated that CRT was mostly localized to the surface of P-CSLCs and did not correlate with the levels of CD44v9, another P-CSLC biomarker. Furthermore, the side population in the CRThigh /CD44v9low population was much higher than that in the CRTlow /CD44v9high population. Calreticulin expression was also assessed by immunohistochemistry in pancreatic cancer tissues (n = 80) obtained after radical resection and was found to be associated with patients' clinicopathological features and disease outcomes in the Cox proportional hazard regression model. Multivariate analysis identified CRT as an independent prognostic factor for pancreatic cancer patients, along with age and postoperative therapy. Our results suggest that CRT can serve as a biomarker of P-CSLCs and a prognostic factor associated with poorer survival of pancreatic cancer patients. This novel biomarker can be considered as a therapeutic target for cancer immunotherapy.

Stimulation of Cell Migration by Flagellin Through the p38 MAP Kinase Pathway in Cultured Intestinal Epithelial Cells.

Toll-like receptor 5 (TLR5) is a receptor for flagellin and is present on the basolateral surface of intestinal epithelial cells. However, the pathological roles of TLR5 in intestinal epithelial cells are not clear at present. In previous reports, we demonstrated that treatment of cultured alveolar epithelial cells with flagellin activated the p38 mitogen-activated protein kinase (MAPK) pathway and enhanced epithelial-mesenchymal transition induced by transforming growth factor beta 1 (TGF-ß1). In translating our findings in alveolar epithelial cells to intestinal epithelial cells, we found that both flagellin and TGF-ß1 activated p38 MAPK and its downstream protein kinase, MAPK-activated protein kinase-2 (MAPKAPK-2) in an IEC-6 intestinal epithelial cell line. The phosphorylation of HSP27, one of the substrates for MAPKAPK-2, was also increased. TGF-ß1 increased the protein level of α-smooth muscle actin (αSMA), and flagellin enhanced the effect of TGF-ß1. A wound healing assay revealed that flagellin and TGF-ß1 stimulated the migration of cells. SB203580, an inhibitor of p38 MAPK, and an inhibitor of MAPKAPK-2 inhibited flagellin-stimulated migration. These results suggested that TLR5 is involved in the migration of intestinal epithelial cells through activation of the p38 MAPK pathway.

Breast sentinel lymph node navigation with three-dimensional computed tomography-lymphography: a 12-year study.

PURPOSE: To evaluate the utility of three-dimensional (3D) computed tomography (CT)-lymphography (LG) breast sentinel lymph node navigation in our institute. PATIENTS AND METHODS: Between 2002 and 2013, we preoperatively identified sentinel lymph nodes (SLNs) in 576 clinically node-negative breast cancer patients with T1 and T2 breast cancer using 3D CT-LG method. SLN biopsy (SLNB) was performed in 557 of 576 patients using both the images of 3D CT-LG for guidance and the blue dye method. RESULTS: Using 3D CT-LG, SLNs were visualized in 569 (99%) of 576 patients. Of 569 patients, both lymphatic draining ducts and SLNs from the peritumoral and periareolar areas were visualized in 549 (96%) patients. Only SLNs without lymphatic draining ducts were visualized in 20 patients. Drainage lymphatic pathways visualized with 3D CT-LG (549 cases) were classified into four patterns: single route/single SLN (355 cases, 65%), multiple routes/single SLN (59 cases, 11%) single route/multiple SLNs (62 cases, 11%) and multiple routes/multiple SLNs (73 cases, 13%). SLNs were detected in 556 (99.8%) of 557 patients during SLNB. CONCLUSION: CT-LG is useful for preoperative visualization of SLNs and breast lymphatic draining routes. This preoperative method should contribute greatly to the easy detection of SLNs during SLNB.

Involvement of Protein Kinase D1 in Signal Transduction from the Protein Kinase C Pathway to the Tyrosine Kinase Pathway in Response to Gonadotropin-releasing Hormone.

The receptor for gonadotropin-releasing hormone (GnRH) belongs to the G protein-coupled receptors (GPCRs), and its stimulation activates extracellular signal-regulated protein kinase (ERK). We found that the transactivation of ErbB4 was involved in GnRH-induced ERK activation in immortalized GnRH neurons (GT1-7 cells). We found also that GnRH induced the cleavage of ErbB4. In the present study, we examined signal transduction for the activation of ERK and the cleavage of ErbB4 after GnRH treatment. Both ERK activation and ErbB4 cleavage were completely inhibited by YM-254890, an inhibitor of Gq/11 proteins. Down-regulation of protein kinase C (PKC) markedly decreased both ERK activation and ErbB4 cleavage. Experiments with two types of PKC inhibitors, Gö 6976 and bisindolylmaleimide I, indicated that novel PKC isoforms but not conventional PKC isoforms were involved in ERK activation and ErbB4 cleavage. Our experiments indicated that the novel PKC isoforms activated protein kinase D (PKD) after GnRH treatment. Knockdown and inhibitor experiments suggested that PKD1 stimulated the phosphorylation of Pyk2 by constitutively activated Src and Fyn for ERK activation. Taken together, it is highly possible that PKD1 plays a critical role in signal transduction from the PKC pathway to the tyrosine kinase pathway. Activation of the tyrosine kinase pathway may be involved in the progression of cancer.