Switching mechanism from AR to EGFR signaling via 3-O-sulfated heparan sulfate in castration-resistant prostate cancer.

Androgen deprivation therapy is given to suppress prostate cancer growth; however, some cells continue to grow hormone-independently as castration-resistant prostate cancer (CRPC). Sulfated glycosaminoglycans promote ligand binding to receptors as co-receptors, but their role in CRPC remains unknown. Using the human prostate cancer cell line C4-2, which can proliferate in hormone-dependent and hormone-independent conditions, we found that epidermal growth factor (EGF)-activated EGFR-ERK1/2 signaling via 3-O-sulfated heparan sulfate (HS) produced by HS 3-O-sulfotransferase 1 (HS3ST1) is activated in C4-2 cells under hormone depletion. Knockdown of HS3ST1 in C4-2 cells suppressed hormone-independent growth, and inhibited both EGF binding to the cell surface and activation of EGFR-ERK1/2 signaling. Gefitinib, an EGFR inhibitor, significantly suppressed C4-2 cell proliferation and growth of a xenografted C4-2 tumor in castrated mouse. Collectively, our study has revealed a mechanism by which cancer cells switch to hormone-independent growth and identified the key regulator as 3-O-sulfated HS.

Machine-learning predicts time-series prognosis factors in metastatic prostate cancer patients treated with androgen deprivation therapy.

Machine learning technology is expected to support diagnosis and prognosis prediction in medicine. We used machine learning to construct a new prognostic prediction model for prostate cancer patients based on longitudinal data obtained from age at diagnosis, peripheral blood and urine tests of 340 prostate cancer patients. Random survival forest (RSF) and survival tree were used for machine learning. In the time-series prognostic prediction model for metastatic prostate cancer patients, the RSF model showed better prediction accuracy than the conventional Cox proportional hazards model for almost all time periods of progression-free survival (PFS), overall survival (OS) and cancer-specific survival (CSS). Based on the RSF model, we created a clinically applicable prognostic prediction model using survival trees for OS and CSS by combining the values of lactate dehydrogenase (LDH) before starting treatment and alkaline phosphatase (ALP) at 120 days after treatment. Machine learning provides useful information for predicting the prognosis of metastatic prostate cancer prior to treatment intervention by considering the nonlinear and combined impacts of multiple features. The addition of data after the start of treatment would allow for more precise prognostic risk assessment of patients and would be beneficial for subsequent treatment selection.

A clinical investigation of recurrence and lost follow-up after renal cell carcinoma surgery: a single-center, long-term, large cohort, retrospective study.

BACKGROUND: Late recurrence of renal cell carcinoma (RCC) is observed in some postoperative patients. In addition, some of these patients are lost to long-term postoperative follow-up. We reviewed the treatment results and prognosis of postoperative patients with RCC at Chiba University Hospital, with the aim of clarifying the proportion and background of patients lost to follow-up. METHODS: This retrospective study included 1176 RCC patients who underwent radical or/and partial nephrectomy. Overall survival (OS), cancer-specific survival (CSS), recurrence-free survival (RFS), and lost follow-up free survival (LFFS) were evaluated and the risk factors for LFFS identified. RESULTS: The median RFS for stage II and II cases was 188.3 and 104.0 months, respectively. Even in stage I, recurrence was observed in about 20% of patients 20 years after surgery. The Kaplan-Meier curve for LFFS showed a linear descent over time, with 50% of patients lost to follow-up within 25 years. Older age (≥ 62 years), histological type (clear cell RCC), and no recurrence were significant risk factors for lost follow-up. CONCLUSIONS: Long-term follow-up is necessary after RCC surgery because late recurrence cases are not uncommon. We believe that lifelong follow-up with imaging studies is recommended for postoperative RCC patients. Early detection of recurrence in postoperative patients is a very important issue, and it may be worthwhile for improving the prognosis of postoperative patients to focus on patients lost to follow-up who may have been overlooked.

The new preparation method for paraffin-embedded samples applying scanning electron microscopy revealed characteristic features in asthma-induced mice.

In bronchial asthma patients, mucous cell metaplasia (MCM) and fibrosis occur in the bronchial epithelium and interstitium, respectively. The mucus and collagen fibers are identified by Periodic acid-Schiff stain (PAS) or Sirius red stain on optical microscopy. On a scanning electron microscope (SEM) observation, formalin-fixed-paraffin-embedded specimens have high insulation, thereby attenuating the scattered electron signals leading to insufficient contrast. Moreover, there were no staining methods for SEM observation, which characterizes the changes in epithelium and interstitium by enhancing the scattered electrons. In this study, we established a method of coating osmium thin film on pathological tissue specimens using plasma chemical vapor deposition technology. This method ensured the intensity of scattered electron signals and enabled SEM observation. Furthermore, we found that morphological changes in MCM and interstitial fibrosis could be characterized by Grocott stain, which we optimized to evaluate pathological remodeling in bronchial asthma. Using these techniques, we compared asthma-induced mice with Amphiregulin (Areg) knockout mice, and found that Areg induce MCM, but the production of Grocott-stain-positive substrate in the interstitium is Areg-independent. The method developed in this study provides an understanding of the pathological spatial information linked to the ultrastructural changes in cells and interstitium due to disease-related signaling abnormalities.

The heavy chain of 4F2 antigen promote prostate cancer progression via SKP-2.

The 4F2 cell-surface antigen heavy chain (4F2hc) forms a heterodimeric complex with L-type amino acid transporter 1 (LAT1) and transports large neutral essential amino acids. However, in contrast to the traditional role of LAT1 in various cancers, the role of 4F2hc has largely remained unknown. The role of 4F2hc in prostate cancer was studied. Treatment of C4-2 cells with si4F2hc was found to suppress cellular growth, migratory and invasive abilities, with this effect occurring through the cell cycle, with a significant decrease in S phase and a significant increase in G0/G1 phase, suggesting cell cycle arrest. In addition, it was proven by RNA seq that the key to 4F2hc's impact on cancer is SKP2. si4F2hc upregulates the protein expression of cyclin-dependent kinase inhibitors (P21cip1, P27kip1) through the downstream target SKP2. Furthermore, the expression of 4F2hc and LAT1 in prostate cancer cells suggests the importance of 4F2hc. Multivariate analysis showed that high 4F2hc expression was an independent prognostic factor for progression-free survival (HR 11.54, p = 0.0357). High 4F2hc was related to the clinical tumour stage (p = 0.0255) and Gleason score (p = 0.0035). Collectively, 4F2hc contributed significantly to prostate cancer (PC) progression. 4F2hc may be a novel marker and therapeutic target in PC.

Functional analysis of LAT3 in prostate cancer: Its downstream target and relationship with androgen receptor.

L-type amino acid transporter 3 (LAT3, SLC43A1) is abundantly expressed in prostate cancer (PC) and is thought to play an essential role in PC progression through the cellular uptake of essential amino acids. Here, we analyzed the expression, function, and downstream target of LAT3 in PC. LAT3 was highly expressed in PC cells expressing androgen receptor (AR), and its expression was increased by dihydrotestosterone treatment and decreased by bicalutamide treatment. In chromatin immunoprecipitation sequencing of AR, binding of AR to the SLC43A1 region was increased by dihydrotestosterone stimulation. Knockdown of LAT3 inhibited cell proliferation, migration, and invasion, and the phosphorylation of p70S6K and 4EBP-1. Separase (ESPL1) was identified as a downstream target of LAT3 by RNA sequencing analysis. In addition, immunostaining of prostatectomy specimens was performed. In the multivariate analysis, high expression of LAT3 was an independent prognostic factor for recurrence-free survival (hazard ratio: 3.24; P = .0018). High LAT3 expression was correlated with the pathological T stage and a high International Society of Urological Pathology grade. In summary, our results suggest that LAT3 plays an important role in the progression of PC.

Impact of Lymphovascular Invasion on Prognosis in the Patients with Bladder Cancer-Comparison of Transurethral Resection and Radical Cystectomy.

(1) Background: This study aimed to evaluate the associations of lymphovascular invasion (LVI) at first transurethral resection of bladder (TURBT) and radical cystectomy (RC) with survival outcomes, and to evaluate the concordance between LVI at first TURBT and RC. (2) Methods: We analyzed 216 patients who underwent first TURBT and 64 patients who underwent RC at Toho University Sakura Medical Center. (3) Results: LVI was identified in 22.7% of patients who underwent first TURBT, and in 32.8% of patients who underwent RC. Univariate analysis identified ≥cT3, metastasis and LVI at first TURBT as factors significantly associated with overall survival (OS) and cancer-specific survival (CSS). Multivariate analysis identified metastasis (hazard ratio (HR) 6.560, p = 0.009) and LVI at first TURBT (HR 9.205, p = 0.003) as significant predictors of CSS. On the other hand, in patients who underwent RC, ≥pT3, presence of G3 and LVI was significantly associated with OS and CSS in univariate analysis. Multivariate analysis identified inclusion of G3 as a significant predictor of OS and CSS. The concordance rate between LVI at first TURBT and RC was 48.0%. Patients with positive results for LVI at first TURBT and RC displayed poorer prognosis than other patients (p < 0.05). (4) Conclusions: We found that the combination of LVI at first TURBT and RC was likely to provide a more significant prognostic factor.

Preoperative Clinical Predictors of Lymphovascular Invasion of Bladder Tumors at Transurethral Resection Pathology.

BACKGROUND: The assessment of lymphovascular invasion (LVI) on the specimens of a transurethral resection of bladder tumors (TURBT) is very important for risk stratification and decision-making on further treatment for bladder cancer. OBJECTIVES: The present study aimed to identify clinical predictors associated with the risk of bladder cancer with LVI before a first TURBT. METHODS: A total of 291 patients underwent a first TURBT for bladder cancer at Toho University Sakura Medical Center between January 2012 and December 2016. We analyzed predictors of LVI based on data from 217 patients and predictors of high grade and ≥ pT1 tumors based on data from the medical records of 237 patients for comparison with LVI risk factors. RESULTS: Univariate analysis significantly associated LVI with episodes of gross hematuria, positive urinary cytology, and larger, non-papillary and sessile tumors. Multivariate analysis selected larger tumors [odds ratio (OR) 1.39; 95 % confidence interval (CI) 1.08-1.78; p = 0.01], and non-papillary (OR 10.05; 95% CI 3.75-26.91; p < 0.01) and sessile (OR 2.65; 95% CI 1.18-5.93; p = 0.02) tumors as significant predictors of LVI. Some predictors such as tumor size and non-papillary tumors overlapped between high-grade and ≥ pT1 bladder cancer. CONCLUSIONS: These predictors can help clinicians to identify patients with, or who are at high-risk for LVI before undergoing a first TURBT and to determine priorities for preoperative evaluation and scheduling consecutive treatments.

Left ileal conduit: A case report.

INTRODUCTION: When ileal conduit construction is performed for urinary tract drainage during radical cystectomy, the conduit is usually constructed in the right lower abdomen. However, no reports have described ileal conduit construction in the left lower abdomen when it cannot be performed on the right side. In addition, some ingenuity is necessary for construction on the left. CASE PRESENTATION: A 75-year-old woman visited our hospital with chief complaint of gross hematuria. Computed tomography and cystoscopy showed a huge bladder tumor, and blood analysis showed anemia. The patient was treated by radical cystectomy with ileal conduit construction. An ileal conduit was constructed in the left lower abdomen; it was impossible to construct in the right lower abdomen because of the abdominal wall scar hernia due to the past open surgery. CONCLUSION: We herein reported a patient who underwent ileal conduit for urinary diversion on the left side of low abdominal wall.

[A Case of Subcutaneous Scrotal Metastasis from Primary Gastric Cancer].

Metastases to the subcutaneous scrotum are extremely rare. Here, we report a 78-year-old man who presented with pain to the scrotum and inguinal area. Two years ago, he underwent total gastrectomy for gastric cancer. The pain was attributed to increased scrotal wall thickness. Incisional biopsy of the thickened scrotal wall revealed diffused infiltration of the subcutaneous tissue by islands of scirrhous type malignant cells. Moreover, immunohistochemical studies showed that the tumor cells were positive for CK7, CK20, and CDX-2. These features suggested a metastatic adenocarcinoma of upper gastrointestinal origin. Although there were no visceral metastases, the tumor cells were too widely spread to be dissected curatively. Palliative chemotherapy with tegafur, gimeracil, and oteracil (S-1) was restarted, and local pain was subsequently ameliorated. Since scrotal metastasis is unlikely to occur it is difficult to diagnose. Therefore, in patients with groin discomfort or swelling and a history of gastric cancer, metastatic adenocarcinoma should be included in the differential diagnosis for early detection of a tumor.

Detection of Nonpalpable Tiny Axillary Lymph Nodes Surrounded by Adipose Tissue Using a Near-Infrared Camera.

Background: It is not always possible to detect nonpalpable small lymph nodes (LNs) surrounded by adipose tissue under the wavelength of visible light. A newly developed near-infrared camera with InGaAs element was able to capture photographs using light at >1000-nm wavelength, at which the difference in absorbance between water and lipids is large. This study investigated the ability to detect nonvisible small LNs using light at 1300-nm wavelength. Methods and Results: Following retrieval of LNs through axillary LN dissection from 20 patients with breast cancer, residual specimens were simultaneously photographed using light at 970-, 1070-, 1200-, 1300-, 1450-, and 1600-nm wavelengths. A total of 45 specimens were observed pathologically at the selected portions in which the 1300-nm light was absorbed (high absorbance group [HA group], n = 25) and those in which the 970-nm light was absorbed instead (low absorbance group [LA group], n = 20). All specimens categorized in the HA group detected the LNs, whereas none of those categorized in the LA group detected an LN. The sensitivity and specificity in the identification of an LN were 1.0. The LNs detected using this camera were significantly smaller than those detected by surgeons (3.00 ± 2.93 mm vs. 5.90 ± 3.91 mm, p < 0.01). Discussion: The light at 1300-nm wavelength was absorbed by axillary LNs. This camera detected LNs that were undetectable by surgeons. This novel technology may be applied to lymphatic microsurgery and contribute to the development of a minimally invasive LN dissection method.

Development and external validation of a nomogram to predict high-grade papillary bladder cancer before first-time transurethral resection of the bladder tumor.

BACKGROUND: The aim of this study was to identify the clinical predictors related to the risk of high-grade papillary bladder cancer before first-time transurethral resection of a bladder tumor (TUR-Bt), and to develop and validate a nomogram predicting the risk of high-grade papillary bladder cancer. METHODS: A retrospective clinical study of consecutive patients who underwent first-time TUR-Bt for papillary bladder cancer was performed. Medical records were reviewed uniformly, and the following data were collected: age, sex, episodes of urinary symptoms, tumor size, number of tumors, location of the largest tumor (lateral walls, base, posterior wall, dome, and anterior wall), tumor appearance (papillary or non-papillary, pedunculated or sessile), and urinary cytology. Data from 254 patients (Group A) were used for the development of a nomogram, while data from 170 patients (Group B) were used for its external validation. RESULTS: High-grade papillary bladder cancer was pathologically diagnosed in 51.6 and 74.6% of Group A and Group B patients, respectively. Based on univariable analyses in Group A, macrohematuria, tumor size, multiple tumors, appearance, and positive urinary cytology were selected as variables to incorporate into a nomogram. The AUC value was 0.81 for the internal validation (Group A), and 0.78 for the external validation (Group B). This novel nomogram can predict high-grade papillary bladder cancer accurately. CONCLUSIONS: The present nomogram can help clinicians calculate the probability in patients with bladder cancer before TUR-Bt and decide on earlier intervention and priorities for the treatment of patients diagnosed with bladder cancer.

Duration of androgen deprivation therapy and nadir of testosterone at 20 ng/dL predict testosterone recovery to supracastrate level in prostate cancer patients who received external beam radiotherapy.

OBJECTIVES: To determine the predictors of testosterone recovery after termination of androgen deprivation therapy in high/intermediate-risk prostate cancer patients receiving external beam radiation therapy with neoadjuvant and adjuvant androgen deprivation therapy. METHODS: A total of 82 patients who underwent external beam radiation therapy with androgen deprivation therapy for prostate cancer were retrospectively analyzed. Serum testosterone levels after androgen deprivation therapy terminations were studied. Cox proportional hazard models and the Kaplan-Meier method were used for statistical analysis. RESULTS: Median age, baseline testosterone, nadir testosterone and duration of androgen deprivation therapy were 73 years, 456 ng/dL, 16 ng/dL and 26 months, respectively. Androgen deprivation therapy duration of 33 months (hazard ratio 0.13; P = 0.0018), nadir testosterone of 20 ng/dL (hazard ratio 0.35; P = 0.0112) and testosterone >50 ng/dL at 6 months after androgen deprivation therapy termination (hazard ratio 0.21; P = 0.0075) were significantly associated with testosterone recovery to normal levels (200 ng/dL) on multivariate analysis. Androgen deprivation therapy duration of 33 months (hazard ratio 0.31; P = 0.0023) and nadir testosterone of 20 ng/dL (hazard ratio 0.38; P = 0.0012) were significantly associated with testosterone recovery to the supracastrate level (50 ng/dL) on multivariate analysis. After dividing patients into three risk groups, the rate of testosterone recovery to the normal level after 2 years of androgen deprivation therapy termination was 100% in the low-risk group versus 20.8% in the high-risk group (P < 0.0001); the rate of testosterone recovery to the supracastrate level was 100% in the low-risk group versus 51.5% in the high-risk group (P < 0.0001). CONCLUSIONS: Duration of androgen deprivation therapy and achievement of nadir testosterone 20 ng/dL both predict testosterone recovery to the supracastrate level in prostate cancer patients undergoing external beam radiation therapy with androgen deprivation therapy.

External validation of two web-based postoperative nomograms predicting the probability of early biochemical recurrence after radical prostatectomy: a retrospective cohort study.

The present study aimed to validate and compare the predictive accuracies of the Memorial Sloan Kettering Cancer Center (MSKCC) and Johns Hopkins University (JHU) web-based postoperative nomograms for predicting early biochemical recurrence (BCR) after radical prostatectomy (RP) and to analyze clinicopathological factors to predict early BCR after RP using our dataset. The c-index was 0.72 (95% confidence (CI): 0.61-0.83) for the MSKCC nomogram and 0.71 (95% CI: 0.61-0.81) for the and JHU nomogram, demonstrating fair performance in the Japanese population. Furthermore, we statistically analyzed our 174 patients to elucidate prognostic factors for early BCR within 2 years. Lymphovascular invasion (LVI) including lymphatic vessel invasion (ly) was a significant predictor of early BCR in addition to common variables (pT stage, extraprostatic extension, positive surgical margin and seminal vesicle invasion). LVI, particularly ly, may provide a good predictor of early BCR after RP and improve the accuracy of the nomograms.

Clinical predictors for high-grade bladder cancer before first-time transurethral resection of the bladder tumor: a retrospective cohort study.

The aim of this study was to identify the clinical predictors related to the risk of high-grade bladder cancer before first-time transurethral resection of the bladder tumor (TUR-Bt) and to externally validate the accuracy of Shapur's nomogram predicting the risk of high-grade bladder cancer in Japanese patients. As a result, episode of gross hematuria (odds ratio: 2.68, P = 0.02), larger tumor size (odds ratio: 1.89, P < 0.01) and positive urinary cytology (odds ratio: 8.34, P < 0.01) were found to be significant predictors for high-grade bladder cancer. Furthermore, the nomogram showed a high predictive accuracy in our Japanese population (area under the curve: 0.79). Clinicians will be able to predict high-grade bladder cancer using the common factors in Shapur's study and ours, such as tumor size and urinary cytology, and gross hematuria as the additional factor first identified here to decide priorities for the treatment of patients diagnosed with bladder cancer.

Bifurcation phenomena of two self-propelled camphor disks on an annular field depending on system length.

Mode selection and bifurcation of a synchronized motion involving two symmetric self-propelled objects in a periodic one-dimensional domain were investigated numerically and experimentally by using camphor disks placed on an annular water channel. Newton's equation of motion for each camphor disk, whose driving force was the difference in surface tension, and a reaction-diffusion equation for camphor molecules on water were used in the numerical calculations. Among various dynamical behaviors found numerically, four kinds of synchronized motions (reversal oscillation, stop-and-move rotation, equally spaced rotation, and clustered rotation) were also observed in experiments by changing the diameter of the water channel. The mode bifurcation of these motions, including their coexistence, were clarified numerically and analytically in terms of the number density of the disk. These results suggest that the present mathematical model and the analysis of the equations can be worthwhile in understanding the characteristic features of motion, e.g., synchronization, collective motion, and their mode bifurcation.

Investigation of dichotomizing sensory nerve fibers projecting to the lumbar multifidus muscles and intervertebral disc or facet joint or sacroiliac joint in rats.

STUDY DESIGN: Immunohistological analysis of dichotomizing sensory nerve fibers projecting to the lumbar multifidus muscles and intervertebral disc (IVD), facet joint (FJ), or sacroiliac joint (SIJ) in rats. OBJECTIVE: To elucidate dichotomizing sensory nerve fibers projecting to the lumbar multifidus muscles and to IVDs, FJs, or SIJs. SUMMARY OF BACKGROUND DATA: Clinically, the origin of low back pain remains unknown. Multiple studies have identified lumbar muscles, IVDs, FJs, and SIJs as sources of low back pain. Pain may originate directly from lumbar muscles or be referred from the spine, or both. Dorsal root ganglion (DRG) neurons with dichotomizing axons have been reported in several species and are thought to be related to referred pain. METHODS: We used 2 neurotracers, 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (DiI) and fluorogold (FG), in this double-labeling study involving 30 Sprague Dawley rats. DiI was applied to lumbar multifidus muscles in all rats. Simultaneously, FG was applied to the anterior left portion of L5-L6 IVDs in the IVD group (n = 10), to the left L5-L6 FJs in the FJ group (n = 10), and to the left SIJs in the SIJ group (n = 10). Fourteen days after surgery, left DRGs from L1 to L6 were harvested, sectioned, and observed under a fluorescence microscope. RESULTS: We verified the existence of double-labeled DRG neurons (i.e., dichotomizing sensory nerve fibers) projecting to lumbar multifidus muscles and to IVDs, FJs, or SIJs, depending on the group. The proportion of double-labeled cells in all DiI-labeled DRG neurons was higher in the FJ group (6.8%) and SIJ group (7.1%) than in the IVD group (3.1%) (P < 0.05). CONCLUSION: Our results document the presence of dichotomizing sensory nerve fibers projecting to lumbar multifidus muscles and to IVDs, FJs, and SIJs. Referred low back muscle pain may reflect disorders of lumbar posterior structures, such as FJs and SIJs, rather than disorders of lumbar anterior structures, such as IVDs.

Primary sensory neurons with dichotomizing axons projecting to the facet joint and the low back muscle in rats.

BACKGROUND: Clinically, the origin of low back pain is unknown. The pain may originate from the lumbar muscles directly, or it may be referred pain from the spine. Dorsal root ganglion (DRG) neurons with dichotomizing axons have been reported in several species and are thought to be related to referred pain. However, these neurons, which have dichotomizing axons to the lumbar facet joints and to the lumbar muscle, have not been fully investigated. METHODS: Two neurotracers - 1,1'-dioctadecyl-3,3,3',3'- tetramethyl-indocarbocyanine perchlorate (DiI) and fluorogold (FG) - were used in the present double-labeling study. DiI crystals were placed in the right L5/6 facet joint, and FG was applied to right multifidus muscles at the L5 level in 10 rats. Two weeks later, bilateral DRGs from L1 through L6 were harvested, sectioned, and observed under a fluorescence microscope. RESULTS: DiI-labeled DRG neurons innervating the L5/6 facet joint (5.17% of the total DRG neurons) were distributed from L1 to L6. FG-labeled DRG neurons innervating the lower back muscle (15.9% of the total) were also distributed from L1 to L6. Double-labeled DRG neurons were found from L1 to L6. The ratio of total double-labeled/total DiI-labeled DRG neurons was 17% and that of total double-labeled/total FG-labeled DRG neurons was 7%. Approximately 17% of all DRG neurons innervating the facet joints had other axons that extended to the lower back muscle. CONCLUSIONS: This finding provides a possible neuroanatomical explanation for referred low back muscle pain from the lower facet joints.

Low affinity NGF receptor (p75 neurotrophin receptor) inhibitory antibody reduces pain behavior and CGRP expression in DRG in the mouse sciatic nerve crush model.

Nerve growth factor (NGF) and its low-affinity receptor, p75 neurotrophin receptor (p75 NTR), are important mediators of pain. To explore further the mechanisms involved, we examined suppression of pain behavior and expression of neuropeptides such as calcitonin gene-related peptide (CGRP) using a p75 NTR inhibitory antibody, in a mouse sciatic nerve crush model. In the nerve-injured model, 150 microg of a p75 NTR inhibitory antibody or 10 microl of saline were applied. The sciatic nerve in the sham-operated group was uninjured. Mechanical allodynia was measured for 2 weeks. CGRP and p75 NTR expression in L5 dorsal root ganglions (DRGs) was examined immunohistochemically. Mechanical allodynia was found in the two nerve injured groups, but not in the sham-operated group (p < 0.05). However, the magnitude of the mechanical allodynia was significantly decreased after application of p75 NTR inhibitory antibody (p < 0.05). CGRP and p75 NTR immunoreactivity in the L5 DRG neurons was upregulated in the injured nerve groups compared with the sham-operated group; however, p75 NTR inhibitory antibody decreased the CGRP and p75 NTR expression (p < 0.01). Application of the p75 NTR inhibitory antibody to the pinched sciatic nerve suppressed CGRP and p75 NTR expression and pain behavior.

Direct single injection of p38 mitogen-activated protein kinase inhibitor does not affect calcitonin gene-related peptide expression in dorsal root ganglion neurons innervating punctured discs in rats.

STUDY DESIGN.: Immunohistological analysis of punctured disc after application of a p38 MAP kinase inhibitor. OBJECTIVE.: To examine effect of direct application on dorsal root ganglion (DRG) neurons innervating damaged rat discs. SUMMARY OF BACKGROUND DATA.: Degeneration of lumbar discs is one cause of low back pain. Pathogenesis may involve sensory nerve ingrowth into disc inner layers; tumor necrosis factor-alpha (TNF-alpha) is thought to be a major inducer of ingrowth. Because p38 mitogen-activated protein kinase (p38) upregulates TNF-alpha expression and may play a crucial role in pain sensation, we investigated the effect of one injection of inhibitor on expression of the pain-related neuropeptide calcitonin gene-related peptide (CGRP). METHODS.: The neuro-tracer fluoro-gold was applied to the surfaces of L4/5 discs to label the innervating DRG neurons (n = 30). Of 30 rats, 10 were controls, whereas the other 20 were the experimental model (i.e., discs were punctured with 23-gauge needle). P38 specific inhibitor or saline was applied simultaneously (n = 10 each, Puncture + inhibitor and puncture + saline groups). Fourteen days postsurgery, DRGs from L1 to L6 were harvested, sectioned, and immunostained for CGRP. Proportion of CGRP-immunoreactive DRG neurons was evaluated in all groups. RESULTS.: Fluoro-gold-labeled neurons innervating the L4/5 disc were distributed throughout L1 to L6 DRGs in all groups. Proportions of labeled neurons positive for CGRP were 15.2% +/- 8% (controls), 27.2% +/- 10% (puncture + saline), and 25.2% +/- 8% (puncture + inhibitor). Proportion of immunoreactive neurons was significantly increased in the puncture groups compared with controls. However, there was no significant difference between the 2 puncture groups (P > 0.1). CONCLUSION.: In this model, CGRP was upregulated in DRG neurons innervating the damaged disc. However, a direct single application of p38 inhibitor did not suppress CGRP expression in innervating DRG neurons. Future research with p38 inhibitor in this model should evaluate multiple or systemic administration of inhibitor.