The critical roles of tumor-initiating cells and the lymph node stromal microenvironment in human colorectal cancer extranodal metastasis using a unique humanized orthotopic mouse model.

Colorectal cancer (CRC) is the second-most common cause of cancer-related mortality. The most important prognostic factors are lymph node (LN) involvement and extranodal metastasis. Our objective is to investigate the interactions between CD133(+)CXCR4(+) (CXC receptor 4) colorectal cancer tumor-initiating cells (Co-TICs) and the LN stromal microenvironment in human CRC extranodal metastasis. We established a unique humanized orthotopic xenograft model. Luciferase-tagged CRC cell lines and human cancer cells were injected intrarectally into nonobese diabetic/SCID mice. Mesenteric LN stromal cells, stromal cell line HK, or CXCL12 knockdown HK (HK-KD-A3) cells were coinoculated with CRC cells. Tumor growth and metastasis were monitored by bioluminescent imaging and immunohistochemistry. We found that this model mimics the human CRC metastatic pattern with CRC cell lines or patient specimens. Adding LN stromal cells promotes CRC tumor growth and extranodal metastasis (P < 0.001). Knocking down CXCL12 impaired HK cell support of CRC tumor formation and extranodal metastasis. When HK cells were added, sorted CD133(+)CXCR4(+) Co-TICs showed increased tumor formation and extranodal metastasis capacities compared to unseparated and non-Co-TIC populations. In conclusion, both Co-TIC and LN stromal factors play crucial roles in CRC metastasis through the CXCL12/CXCR4 axis. Blocking Co-TIC/LN-stromal interactions may lead to effective therapy to prevent extranodal metastasis.

CD 133+ and CXCR4+ colon cancer cells as a marker for lymph node metastasis.

INTRODUCTION: Colorectal cancer (CRC) stem cells or tumor-initiating cells (Co-TIC) are implicated in both cancer recurrence and extranodal metastasis. CD133 and CXCR4 are specific cell surface markers that are indicators of Co-TIC. The presence of lymph node (LN) metastases is one of the strongest negative prognostic factors for CRC patients. We examined the relationship between the Co-TIC markers CD133 and CXCR4 and LN involvement in CRC. METHODS: CRC cells were isolated via enzymatic digestion. CD133(+), CXCR4(+), and double-positive CRC cells were detected by fluorescence-activated cell sorting analysis. The percentages of CD133(+), CXCR4(+), and double-positive cells were identified and correlated to the number and percentage of positive LN on staging. RESULTS: Twenty-seven samples underwent fluorescence-activated cell sorting analysis. The mean percentage of CD133(+) cells was 3.94% (range 0.15%-19.06%). The mean percentage of CXCR4(+) cells was 6.15% (range 0%-27.11%). The mean percentage of CD133(+)CXCR4(+) cells was 0.45% (range 0%-2.08%). Thirteen patients had LN metastasis: 8 N1 disease and 5 N2 disease. The correlation coefficients between the percentage of Co-TIC marker-positive cells and percentage of positive LN were r = 0.58 (P = 0.0016) for CD133(+) cells, r = 0.36 (P = 0.5868) for CXCR4(+) cells, and r = 0.56 (P = 0.0022) for double-positive cells. DISCUSSION: Our results show CD133(+) and CD133(+)CXCR4(+) cancer cells correlate with the presence of LN metastasis in CRC. Further studies will examine whether these markers can give consistent prognostic information and may help to develop novel diagnostic and therapeutic options.

A rare fraction of drug-resistant follicular lymphoma cancer stem cells interacts with follicular dendritic cells to maintain tumourigenic potential.

Follicular lymphoma (FL) comprises nearly 25% of non-Hodgkin lymphoma cases and is clinically characterized by initial sensitivity to chemotherapy followed by relapse. FL stroma contains a special type of stromal cell found in the germinal centre of lymph nodes-the follicular dendritic cell (FDC). We first isolated tumourigenic cells from the FL cell line FLK-1 by side population (SP) technique, and found that SP cells, which express ABCG2, were enriched by chemotherapy and radiation treatments. In vitro, SP cells were attracted by and adhered to FDCs through chemokine (C-X-C motif) ligand 12/chemokine (C-X-C motif) receptor 4 (CXCL12/CXCR4) signalling. In vivo, limiting dilution assays showed SP cells were highly enriched in cancer stem cells (CSC), but required FDC for tumour formation in non-obese diabetic/severe combined immunodeficiency mice. Treatment with AMD3100, a specific CXCL12/CXCR4 inhibitor, eliminated tumour growth. These findings were then verified with FL cells isolated from an FL patient's ascitic fluid (FLA-1). Finally, we detected the ABCG2 expressing lymphoma cells in FL clinical specimens. Thus, we found that the highly tumourigenic FL cells having CSC-like activities (FL-SC) interact with FDCs in a CXCL12/CXCR4 dependent manner to resist chemotherapy. Our results indicate the importance of FL-SC and niche cell signalling in maintaining tumourigenicity. These signals represent novel targets for CSC eradication.

Use of topical imiquimod in the treatment of VIN: a case report and review of the literature.

Vulvar intraepithelial neoplasia (VIN) is a premalignant disease of the vulvar squamous epithelium. Standard treatment for VIN lesions is surgical excision. Alternative therapeutic options for conservative treatment have been sought by patients to prevent disfigurement and to preserve sexual function. We present such a patient in whom topical imiquimod was used with a successful outcome. Imiquimod is effective in the treatment of VIN, as well as convenient, self-administered, and generally well tolerated.

Lymph node stromal cells enhance drug-resistant colon cancer cell tumor formation through SDF-1α/CXCR4 paracrine signaling.

Colorectal cancer (CRC) is the third most common malignancy and the second leading cause of cancer-related deaths in America. Nearly two thirds of newly diagnosed CRC cases include lymph node (LN) involvement, and LN metastasis is one of the strongest negative prognostic factors for CRC. It is thought that CRC tumors contain a small population of drug-resistant CRC tumor-initiating cells (Co-TICs) that may be responsible for cancer recurrence. To evaluate the effects of the LN stromal cells on Co-TICs, we established a unique xenoplant model using CRC cells isolated by enzymatic digestion from consented patient specimens, HT-29 cells, HCA-7 cells, and LN stromal cell line HK cells. We found that HK cells and HK cell-conditioned media enhanced CRC tumor formation and tumor angiogenesis. Cells expressing CD133(+) and the stromal cell-derived factor 1α (SDF-1α) receptor CXCR4 were enriched in chemotherapeutic-resistant CRC cells. CD133(+)CXCR4(+) Co-TICs isolated from patient specimens are more tumorigenic than unsorted tumor cells. Furthermore, the inhibitors specific to HK cell-derived SDF-1α reduced tumor formation and tumor angiogenesis. Our results have demonstrated a role for Co-TICs in tumor growth and defined the influence of LN stromal cells on Co-TICs. We have identified a major Co-TIC/LN microenvironment-specific mechanism for CRC resistance to chemotherapeutic agents and established experimental platforms for both in vitro and in vivo testing, indicating that SDF-1α and its receptor, CXCR4, may be targets for clinical therapy.

Analyzing habituation responses to novelty in zebrafish (Danio rerio).

Analysis of habituation is widely used to characterize animal cognitive phenotypes and their modulation. Although zebrafish (Danio rerio) are increasingly utilized in neurobehavioral research, their habituation responses have not been extensively investigated. Utilizing the novel tank test, we examine intra- and inter-session habituation and demonstrate robust habituation responses in adult zebrafish. Analyzing the intra-session habituation to novelty further, we also show that selected anxiogenic drugs (caffeine, pentylenetetrazole), as well as stress-inducing alarm pheromone, attenuated zebrafish habituation. Some acute anxiolytic agents, such as morphine and ethanol, while predictably reducing zebrafish anxiety, had no effects on habituation. Chronic ethanol and fluoxetine treatments improved intra-session habituation in zebrafish. In general, our study parallels literature on rodent habituation responses to novelty, and reconfirms zebrafish as a promising model for cognitive neurobehavioral research.

The effects of chronic social defeat stress on mouse self-grooming behavior and its patterning.

Stress induced by social defeat is a strong modifier of animal anxiety and depression-like phenotypes. Self-grooming is a common rodent behavior, and has an ordered cephalo-caudal progression from licking of the paws to head, body, genitals and tail. Acute stress is known to alter grooming activity levels and disrupt its patterning. Following 15-17 days of chronic social defeat stress, grooming behavior was analyzed in adult male C57BL/6J mice exhibiting either dominant or subordinate behavior. Our study showed that subordinate mice experience higher levels of anxiety and display disorganized patterning of their grooming behaviors, which emerges as a behavioral marker of chronic social stress. These findings indicate that chronic social stress modulates grooming behavior in mice, thus illustrating the importance of grooming phenotypes for neurobehavioral stress research.

Modeling withdrawal syndrome in zebrafish.

The zebrafish (Danio rerio) is rapidly becoming a popular model species in behavioral neuroscience research. Zebrafish behavior is robustly affected by environmental and pharmacological manipulations, and can be examined using exploration-based paradigms, paralleled by analysis of endocrine (cortisol) stress responses. Discontinuation of various psychotropic drugs evokes withdrawal in both humans and rodents, characterized by increased anxiety. Sensitivity of zebrafish to drugs of abuse has been recently reported in the literature. Here we examine the effects of ethanol, diazepam, morphine and caffeine withdrawal on zebrafish behavior. Overall, discontinuation of ethanol, diazepam and morphine produced anxiogenic-like behavioral or endocrine responses, demonstrating the utility of zebrafish in translational research of withdrawal syndrome.