Andrea M Stringer

Publications of Andrea M Stringer

• Irinotecan-induced alterations in intestinal cell kinetics and extracellular matrix component expression in the dark agouti rat.

  Authors: Noor Al-Dasooqi, Joanne M Bowen, Rachel J Gibson, Richard M Logan, Andrea M Stringer, Dorothy M Keefe

  International journal of experimental pathology. 04/2011; 92(5):357-65.

  Chemotherapy-induced mucositis is characterized by damage of mucous membranes throughout the alimentary tract (AT). Extracellular matrix (ECM) components play a vital role in maintaining mucosalChemotherapy-induced mucositis is characterized by damage of mucous membranes throughout the alimentary tract (AT). Extracellular matrix (ECM) components play a vital role in maintaining mucosal barrier integrity by regulating cellular apoptosis, proliferation and differentiation of overlying epithelial cells. The aims of this study were to characterize the changes in epithelial cell kinetics and to investigate the expression of the ECM components in the gastrointestinal tract following irinotecan administration. Female dark agouti rats were treated with single 200 mg/kg dose irinotecan and killed at various time points (1, 6, 24, 48, 72, 96 and 14 h) after treatment. Ki67 immunostaining and TUNEL were used to assess proliferation and apoptosis, respectively, in the jejunum and colon. Masson trichrome staining and picro-sirius red staining were used to determine the level of collagen, and immunohistochemistry was used to further assess collagen IV, fibronectin and laminin 1 and 2 expression in these tissues. Irinotecan halved cellular proliferation in the jejunum and colon at 48 and 24 h, respectively, while apoptosis peaked at 6 h (P < 0.05). There was a substantial increase in total collagen deposits around crypts from 24 h in both regions. However, collagen IV expression decreased significantly in the crypt region in a delayed fashion (P < 0.05). Fibronectin expression decreased significantly in jejunum and colon from 6 to 24 h following treatment (P < 0.05). Irinotecan induced a significant alteration in epithelial cell kinetics in both the jejunum and colon, and this correlated with changes in ECM component expression. Changes in ECM expression may have a direct impact on the loss of mucosal layer integrity evident in chemotherapy-induced mucositis.

• Selection of housekeeping genes for gene expression studies in a rat model of irinotecan-induced mucositis.

  Authors: Noor Al-Dasooqi, Joanne M Bowen, Rachel J Gibson, Richard M Logan, Andrea M Stringer, Dorothy M Keefe

  Chemotherapy. 02/2011; 57(1):43-53.

  Mucositis is the term used to describe damage caused by chemotherapy to mucous membranes of the alimentary tract. RT-PCR has recently been utilised to determine the molecular events that occur inMucositis is the term used to describe damage caused by chemotherapy to mucous membranes of the alimentary tract. RT-PCR has recently been utilised to determine the molecular events that occur in mucositis. As this method relies on the use of a validated endogenous control, this study aims to validate commonly used housekeeping genes in an irinotecan-induced mucositis model. Rats were administered irinotecan and sacrificed at different time points, in particular 1, 24, 72 and 144 h following treatment. Histopathological damage was assessed by haematoxylin and eosin staining. RT-PCR was used to evaluate the expression of 11 housekeeping genes. Expression stability was determined by the Normfinder program. Matrix metalloproteinase 2 was used as a target gene to validate the appropriateness of the top-ranking housekeeping gene. For normalisation to multiple housekeeping genes, the most stable combination across all time points in the jejunum was Ywhaz/UBC and in the colon UBC/β-actin. SDHA and GAPDH were the most variable genes in the jejunum and colon where they were 4.4 and 3.2 fold upregulated following irinotecan, respectively. For normalisation of irinotecan-induced mucositis gene expression studies, a combination of Ywhaz/UBC and UBC/β-actin should be used in the jejunum and colon, respectively. UBC is the most favourable if restricted to a single housekeeping gene across all time points.

• Matrix metalloproteinases are possible mediators for the development of alimentary tract mucositis in the dark agouti rat.

  Authors: Noor Al-Dasooqi, Rachel J Gibson, Joanne M Bowen, Richard M Logan, Andrea M Stringer, Dorothy M Keefe

  Experimental biology and medicine (Maywood, N.J.). 10/2010; 235(10):1244-56.

  Alimentary tract (AT) mucositis is a serious and debilitating side-effect of cancer therapy primarily characterized by damage of the mucous membranes throughout the AT. It is well established thatAlimentary tract (AT) mucositis is a serious and debilitating side-effect of cancer therapy primarily characterized by damage of the mucous membranes throughout the AT. It is well established that this damage is a result of up-regulation of stress response genes and pro-inflammatory cytokines. Matrix metalloproteinases (MMPs) have been shown to function in several of the pathways known to be up-regulated in mucositis and play a key role in tissue injury and inflammation in many gastrointestinal disorders. This study aims to characterize the expression of multiple MMPs including MMP-1, -2, -3, -9 and -12 and their inhibitors, tissue inhibitor of metalloproteinase (TIMP)-1 and -2, in a rat model of irinotecan-induced mucositis. Dark agouti rats were administered a single 200 mg/kg intraperitoneal dose of irinotecan and killed at 1, 6, 24, 48, 72, 96 and 144 h following treatment. Hematoxylin and eosin staining, immunohistochemistry and realtime polymerase chain reaction were used to assess histopathological damage and MMP expression in the jejunum and colon. Marked histopathological evidence of mucositis was observed in the jejunum and colon as early as six hours following irinotecan treatment. A significant alteration in both gene expression and tissue levels of MMPs and TIMPs was noted following irinotecan. The increase in MMP-2, -3, -9 and -12 levels was associated with inflammatory infiltrate and maximum tissue damage. In contrast, MMP-1 expression correlated with tissue restitution. TIMP-1 and -2 levels were significantly altered in the jejunum following irinotecan. The augmentation in the expression profiles of MMPs and their inhibitors correlated with histopathological alterations observed in the tissue following irinotecan. This prompts the consideration of MMPs as possible mediators of chemotherapy-induced mucositis.

• Pro-inflammatory cytokines play a key role in the development of radiotherapy-induced gastrointestinal mucositis.

  Authors: Zhi Yi Ong, Rachel J Gibson, Joanne M Bowen, Andrea M Stringer, Jocelyn M Darby, Richard M Logan, Ann Sj Yeoh, Dorothy M Keefe

  Radiation oncology (London, England). 03/2010; 5:22.

  Mucositis is a toxic side effect of anti-cancer treatments and is a major focus in cancer research. Pro-inflammatory cytokines have previously been implicated in the pathophysiology ofMucositis is a toxic side effect of anti-cancer treatments and is a major focus in cancer research. Pro-inflammatory cytokines have previously been implicated in the pathophysiology of chemotherapy-induced gastrointestinal mucositis. However, whether they play a key role in the development of radiotherapy-induced gastrointestinal mucositis is still unknown. Therefore, the aim of the present study was to characterise the expression of pro-inflammatory cytokines in the gastrointestinal tract using a rat model of fractionated radiotherapy-induced toxicity. Thirty six female Dark Agouti rats were randomly assigned into groups and received 2.5 Gys abdominal radiotherapy three times a week over six weeks. Real time PCR was conducted to determine the relative change in mRNA expression of pro-inflammatory cytokines IL-1beta, IL-6 and TNF in the jejunum and colon. Protein expression of IL-1beta, IL-6 and TNF in the intestinal epithelium was investigated using qualitative immunohistochemistry. Radiotherapy-induced sub-acute damage was associated with significantly upregulated IL-1beta, IL-6 and TNF mRNA levels in the jejunum and colon. The majority of pro-inflammatory cytokine protein expression in the jejunum and colon exhibited minimal change following fractionated radiotherapy. Pro-inflammatory cytokines play a key role in radiotherapy-induced gastrointestinal mucositis in the sub-acute onset setting.

• Kinetics and regional specificity of irinotecan-induced gene expression in the gastrointestinal tract.

  Authors: Joanne M Bowen, Anna Tsykin, Andrea M Stringer, Richard M Logan, Rachel J Gibson, Dorothy M K Keefe

  Toxicology. 02/2010; 269(1):1-12.

  Gastrointestinal toxicity remains a significant and dose-limiting complication of cancer treatment. While the pathophysiology is becoming clearer, considerable gaps in the knowledge remainGastrointestinal toxicity remains a significant and dose-limiting complication of cancer treatment. While the pathophysiology is becoming clearer, considerable gaps in the knowledge remain surrounding the timing and site-specific gene changes which occur in response to insult. As such, this study aimed to assess gene expression profiles in a number of regions along the gastrointestinal tract following treatment with the chemotherapy agent, irinotecan, and correlate them with markers of cell death and tissue damage. Data analysis of microarray results found that genes involved in apoptosis, mitogen activated kinase (MAPK) signalling and inflammation were upregulated within 6h, while genes involved in cell proliferation, wound healing and blood vessel formation were upregulated at later time points up to 72 h. Cell death was significantly increased at 6 and 24h, and the stomach showed the lowest severity of overt tissue damage. Real time PCR of MAPK signalling pathway genes found that the jejunum and colon had significantly increased expression in a number of genes at 72 h, where as the stomach was unchanged. These results indicate that overall severity of tissue damage may be determined by precisely timed target gene responses specific to each region. Therapeutic targeting of key gene responses at the appropriate time point may prove to be effective for prevention of chemotherapy-induced gastrointestinal damage.

• Irinotecan-induced mucositis manifesting as diarrhoea corresponds with an amended intestinal flora and mucin profile.

  Authors: Andrea M Stringer, Rachel J Gibson, Joanne M Bowen, Richard M Logan, Kimberly Ashton, Ann S J Yeoh, Noor Al-Dasooqi, Dorothy M K Keefe

  International journal of experimental pathology. 10/2009; 90(5):489-99.

  Chemotherapy-induced diarrhoea is a major oncological problem, caused by the cytotoxic effects of cancer chemotherapy. Irinotecan is linked with severe mucositis and diarrhoea, the mechanisms ofChemotherapy-induced diarrhoea is a major oncological problem, caused by the cytotoxic effects of cancer chemotherapy. Irinotecan is linked with severe mucositis and diarrhoea, the mechanisms of which remain poorly understood. Bacterial beta-glucuronidase is thought to be involved in the metabolism of irinotecan, implicating the intestinal flora. Intestinal mucins may also be implicated in the development of chemotherapy-induced diarrhoea. Rats were treated with 200 mg/kg of irinotecan and killed at 96, 120 and 144 h. The rats were monitored for diarrhoea. Pathology and immunohistochemical staining was performed. The samples were cultured and faecal DNA was analysed using real-time polymerase chain reaction. Severe diarrhoea was observed from 72 to 96 h. A decrease in body mass was also observed after treatment. Significant changes in goblet cell numbers (both complete and cavitated cells) were observed in the small and large intestines. Changes in MUC gene expression were observed in the small intestine only. Modifications were observed to the intestinal flora profile, especially Escherichia coli, and an increase in the expression of beta-glucuronidase was detected. In conclusion, irinotecan-induced diarrhoea may be caused by an increase in some beta-glucuronidase-producing bacteria, especially E. coli, exacerbating the toxicity of active metabolites. Accelerated mucous secretion and mucin release may also contribute to the delayed onset of diarrhoea.

• Chemotherapy-induced diarrhoea.

  Authors: Rachel J Gibson, Andrea M Stringer

  Current opinion in supportive and palliative care. 04/2009; 3(1):31-5.

  PURPOSE OF REVIEW: Diarrhoea is a major manifestation of chemotherapy-induced mucositis that until recently has received very little attention. To date, there is no detailed understanding of thePURPOSE OF REVIEW: Diarrhoea is a major manifestation of chemotherapy-induced mucositis that until recently has received very little attention. To date, there is no detailed understanding of the underlying mechanisms of the condition. The purpose of this review is to examine the plethora of recent studies, both in the laboratory and in the clinic, which have attempted to elucidate effective treatment options. RECENT FINDINGS: Over recent years, there have been many new treatment options trialled for ameliorating chemotherapy-induced diarrhoea. Some of these have shown great promise in small clinical studies and now need to be investigated in larger trials. Furthermore, there have been developments in the understanding of the underlying mechanisms of chemotherapy-induced diarrhoea. These developments may also lead to effective treatment options. SUMMARY: Here, we describe the current thinking behind the mechanisms of chemotherapy-induced diarrhoea and present current and new treatment options. This opinion article highlights the shift towards more effective research into diarrhoea caused by chemotherapy.

• Characterisation of mucosal changes in the alimentary tract following administration of irinotecan: implications for the pathobiology of mucositis.

  Authors: Richard M Logan, Rachel J Gibson, Joanne M Bowen, Andrea M Stringer, Stephen T Sonis, Dorothy M K Keefe

  Cancer chemotherapy and pharmacology. 07/2008; 62(1):33-41.

  PURPOSE: The pathobiology of alimentary tract (AT) mucositis is complex and there is limited information about the events which lead to the mucosal damage that occurs during cancer treatment. VariousPURPOSE: The pathobiology of alimentary tract (AT) mucositis is complex and there is limited information about the events which lead to the mucosal damage that occurs during cancer treatment. Various transcription factors and proinflammatory cytokines are thought to play important roles in pathogenesis of mucositis. The aim of this study was to determine the expression of nuclear factor-kappaB (NF-kappaB), tumor necrosis factor (TNF) and interleukins-1beta (IL-1beta) and -6 (IL-6) in the AT following the administration of the chemotherapeutic agent irinotecan. METHODS: Eighty-one female dark Agouti rats were assigned to either control or experimental groups according to a specific time point. Following administration of irinotecan, rats were monitored for the development of diarrhoea. The rats were killed at times ranging from 30 min to 72 h after administration of irinotecan. Oral mucosa, jejunum and colon were collected and standard immunohistochemical techniques were used to identify NF-kappaB, TNF, IL-1beta and IL-6 within the tissues. Sections were also stained with haematoxylin and eosin for histological examination. RESULTS: Irinotecan caused mild to moderate diarrhoea in a proportion of the rats that received the drug. Altered histological features of all tissues from rats administered irinotecan were observed which included epithelial atrophy in the oral mucosa, reduction of villus height and crypt length in the jejunum and a reduction in crypt length in the colon. Tissue staining for NF-kappaB, TNF and IL-1beta and IL-6 peaked at between 2 and 12 h in the tissues examined. CONCLUSIONS: This is the first study to demonstrate histological and immunohistochemical evidence of changes occurring concurrently in different sites of the AT following chemotherapy. The results of the study provide further evidence for the role of NF-kappaB and associated pro-inflammatory cytokines in the pathobiology of AT mucositis. The presence of these factors in tissues from different sites of the AT also suggests that there may be a common pathway along the entire AT causing mucositis following irinotecan administration.

• Gene expression analysis of multiple gastrointestinal regions reveals activation of common cell regulatory pathways following cytotoxic chemotherapy.

  Authors: Joanne M Bowen, Rachel J Gibson, Anna Tsykin, Andrea M Stringer, Richard M Logan, Dorothy M K Keefe

  International journal of cancer. Journal international du cancer. 11/2007; 121(8):1847-56.

  Gastrointestinal mucositis involves many changes at the gene level, affecting epithelial/subepithelial interactions and leading to overt damage. The regional specificity and time course of theseGastrointestinal mucositis involves many changes at the gene level, affecting epithelial/subepithelial interactions and leading to overt damage. The regional specificity and time course of these changes, and how they relate to subsequent mucositis development however remain unknown. The aim of this study was to determine the early time course of gene expression changes along the gastrointestinal tract of the DA rat following chemotherapy. Female DA rats were treated with a single dose of 200 mg/kg irinotecan to induce mucositis, and were killed at short intervals following treatment. Small sections of stomach, jejunum and colon were harvested for analysis of genetic profiles. RNA was hybridised to high density Affymetrix oligonucleotide microarrays. Data analysis was carried out with software package, TimeCourse, freely available through Bioconductor. As early as 1 hr following chemotherapy, expression of hundreds of genes was altered, including those for transcription factors, stress response proteins and protein turnover. These genes are involved in cell proliferation, differentiation and apoptosis along with other cellular processes. At early time points, there was a significant response involving the mitogen-activated protein kinase pathway, cell cycle regulation and cytokine receptor signalling. At later time points, changes to the complement cascade became prominent. We have shown that changes in gene expression following chemotherapy occur by 1 hr, and persist for at least 72 hr after treatment. Many of these changes are highly likely to be specifically related to the subsequent development of gastrointestinal mucositis.

• VSL#3 probiotic treatment reduces chemotherapy-induced diarrhea and weight loss.

  Authors: Joanne M Bowen, Andrea M Stringer, Rachel J Gibson, Ann S J Yeoh, Sarah Hannam, Dorothy M K Keefe

  Cancer biology & therapy. 10/2007; 6(9):1449-54.

  BACKGROUND: One of the most common toxicities of cancer treatment is diarrhea. Probiotics have been shown effective at preventing diarrhea in inflammatory bowel disease and may prove useful in theBACKGROUND: One of the most common toxicities of cancer treatment is diarrhea. Probiotics have been shown effective at preventing diarrhea in inflammatory bowel disease and may prove useful in the oncology setting. AIM: The primary aim of this study was to investigate the probiotic mixture, VSL#3, for amelioration of chemotherapy-induced diarrhea (CID). METHODS: This experiment was carried out in a clinically relevant model of CID. VSL#3 was administered to female DA rats in one of three schedules. Irinotecan was used to induce mucositis and diarrhea, with rats monitored for seven days to record incidence of weight-loss and diarrhea. At study completion, intestines were collected to investigate histological and proliferative changes, apoptosis levels and mucin composition. Results: VSL#3 reduced weight loss following irinotecan when administered before and after chemotherapy. Moderate and severe diarrhea was also prevented in these rats. This was associated with a significant increase in crypt proliferation combined with an inhibition of apoptosis in both the small and large intestines. VSL#3 also prevented irinotecan-induced increases in goblet cells within jejunal crypts. CONCLUSIONS: VSL#3 is effective at preventing severe diarrhea following chemotherapy with irinotecan and therefore has potential to be used clinically by cancer patients.

• A novel animal model to investigate fractionated radiotherapy-induced alimentary mucositis: the role of apoptosis, p53, nuclear factor-kappaB, COX-1, and COX-2.

  Authors: Ann S J Yeoh, Rachel J Gibson, Eric E K Yeoh, Joanne M Bowen, Andrea M Stringer, Kar A Giam, Dorothy M K Keefe

  Molecular cancer therapeutics. 09/2007; 6(8):2319-27.

  Radiation-induced mucositis is a common and serious side effect of radiotherapy. Molecular mechanisms of mucosal injury, however, are still poorly understood and extremely difficult to study inRadiation-induced mucositis is a common and serious side effect of radiotherapy. Molecular mechanisms of mucosal injury, however, are still poorly understood and extremely difficult to study in humans. A novel Dark Agouti rat model using fractionated radiotherapy to induce mucositis has been developed to investigate the occurrence of alimentary mucosal injury. Twenty-four Dark Agouti rats were randomly assigned to receive either fractionated radiotherapy or no radiotherapy. The irradiated rats received a fractionated course of abdominal radiotherapy at 45 Gy/18 fractions/6 weeks treating thrice weekly (i.e., at a radiation dose of 2.5 Gy per fraction). After each week of radiation, a group of irradiated rats was killed. Histomorphology and mucin distribution in the alimentary tract was investigated. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used to examine apoptosis in the colon and jejunum, and intestinal morphometry was used to assess villus length, crypt length, and mitotic crypt count. Immunohistochemistry of p53, nuclear factor-kappaB, cyclooxygenase (COX)-1, and COX-2 was also done. The fractionated radiotherapy course induced alimentary mucositis from week 1, with more severe injury seen in the small intestine. The hallmark appearance of apoptosis was present in the crypts of the small and large intestine. In the jejunum and colon, goblet cell disorganization and degeneration was obvious and crypt mitotic counts were severely depleted throughout the treatment. Expression of p53, nuclear factor-kappaB, COX-1, and COX-2 was increased in the irradiated intestinal sections. Fractionated radiation-induced alimentary mucositis has been effectively documented in the Dark Agouti rat for the first time. Further studies investigating the molecular mechanisms underlying radiation-induced mucositis are planned to ultimately achieve anti-mucotoxic-targeted therapies.

• The role of pro-inflammatory cytokines in cancer treatment-induced alimentary tract mucositis: pathobiology, animal models and cytotoxic drugs.

  Authors: Richard M Logan, Andrea M Stringer, Joanne M Bowen, Ann S J Yeoh, Rachel J Gibson, Stephen T Sonis, Dorothy M K Keefe

  Cancer treatment reviews. 09/2007; 33(5):448-60.

  Alimentary tract (AT) mucositis can be a major problem for patients undergoing cancer treatment. It has significant clinical and economic consequences and is a major factor that can compromise theAlimentary tract (AT) mucositis can be a major problem for patients undergoing cancer treatment. It has significant clinical and economic consequences and is a major factor that can compromise the provision of optimal treatment for patients. The pathobiology of AT mucositis is complex and the exact mechanisms that underlie its development still need to be fully elucidated. Current opinion considers that there is a prominent interplay between all of the compartments of the mucosa involving, at a molecular level, the activation of transcription factors, particularly nuclear factor-kappaB, and the subsequent upregulation of pro-inflammatory cytokines and inflammatory mediators. The purpose of this review is to examine the literature relating to what is currently known about the pathobiology of AT mucositis, particularly with respect to the involvement of pro-inflammatory cytokines, as well as currently used animal models and the role of specific cytotoxic chemotherapy agents in the development of AT mucositis.

• Chemotherapy-induced mucositis: the role of gastrointestinal microflora and mucins in the luminal environment.

  Authors: Andrea M Stringer, Rachel J Gibson, Joanne M Bowen, Richard M Logan, Ann S J Yeoh, Dorothy M K Keefe

  The journal of supportive oncology. 07/2007; 5(6):259-67.

  Collectively, mucositis refers to the damage caused to the mucous membranes of the body following cytotoxic cancer therapy. Diarrhea is one such manifestation of mucositis and is a common side effectCollectively, mucositis refers to the damage caused to the mucous membranes of the body following cytotoxic cancer therapy. Diarrhea is one such manifestation of mucositis and is a common side effect of chemotherapy that remains poorly understood. It affects the entire gastrointestinal tract. The exact number of patients affected by diarrhea as a result of treatment is uncertain, although it is believed that approximately 10% of patients with advanced cancer will be affected. Despite advances in the understanding of oral and small intestinal mucositis over recent years, large intestinal mucositis, including diarrhea, has not been well defined, and the underlying mechanisms of the condition have yet to be established. The majority of the literature concerning diarrhea is based on clinical observations, with little basic research. However, from the research conducted, it is likely that the intestinal microflora play a role in the development of chemotherapy-induced diarrhea. This review will examine in detail what is known about the mechanisms of chemotherapy-induced diarrhea and will explore the potentially important relationship among intestinal microflora, the luminal environment, and the subsequent development of chemotherapy-induced diarrhea.

• Velafermin improves gastrointestinal mucositis following irinotecan treatment in tumor-bearing DA rats.

  Authors: Rachel J Gibson, Andrea M Stringer, Joanne M Bowen, Richard M Logan, Ann S J Yeoh, Jaimi Burns, Enrique Alvarez, Dorothy M K Keefe

  Cancer biology & therapy. 05/2007; 6(4):541-7.

  Mucositis is a common, costly and unpleasant side effect of cancer chemotherapy and radiotherapy. Velafermin (FGF-20) has shown the potential to reduce these side effects. Irinotecan is aMucositis is a common, costly and unpleasant side effect of cancer chemotherapy and radiotherapy. Velafermin (FGF-20) has shown the potential to reduce these side effects. Irinotecan is a chemotherapeutic agent which is commonly used in solid tumors, and causes GI mucositis manifested by severe diarrhea. Therefore the primary aim of this study was to investigate whether velafermin reduces the GI mucositis induced by irinotecan. The secondary aim was to test varying schedules of administration of velafermin. Groups of tumor-bearing DA rats (6 per group) were treated with varying doses (4, 8 or 16 mg/kg) of velafermin intraperitoneally either prior to, prior to and during, or after chemotherapy treatment. Rats received a single dose of 200 mg/kg irinotecan intraperitoneally. Rats were monitored closely for the incidence and severity of diarrhea and mortality before being killed 192 h following treatment. Mortality, diarrhea and histopathology were assessed throughout the gastrointestinal tract. Severe or moderate diarrhea occurred in approximately 40% of rats treated with irinotecan alone. This was associated with a 50% mortality rate 96 h following chemotherapy. Velafermin administered at 16 mg/kg prior to irinotecan improved gastrointestinal mucositis as measured by reduced diarrhea and mortality following irinotecan chemotherapy in the DA rat. Rats that received velafermin prior to, or prior to and during irinotecan treatment did develop severe or moderate diarrhea, however it occurred later, in fewer rats and was not associated with mortality. Other dosing regimens were not as effective. This has important implications for the use of velafermin in GI mucositis in humans, and should be further studied.

• Role of p53 in irinotecan-induced intestinal cell death and mucosal damage.

  Authors: Joanne M Bowen, Rachel J Gibson, Andrea M Stringer, Thong W Chan, Avanita S Prabowo, Adrian G Cummins, Dorothy M K Keefe

  Anti-cancer drugs. 03/2007; 18(2):197-210.

  Irinotecan treatment of colorectal cancers results in high-grade intestinal mucositis in a large proportion of patients. The mechanisms behind irinotecan-induced mucosal injury, however, have yet toIrinotecan treatment of colorectal cancers results in high-grade intestinal mucositis in a large proportion of patients. The mechanisms behind irinotecan-induced mucosal injury, however, have yet to be fully explained. The aim of this study was to investigate the role of the p53 protein in the onset of intestinal damage following irinotecan treatment in two different settings. IEC-6 and FHs 74 intestinal cell lines were treated with irinotecan with and without a temporary p53 inhibitor, pifithrin-alpha, and examined for changes in proliferation and survival along with expression of p53 and related proteins. Forty tumour-bearing rats also underwent irinotecan treatment with and without pifithrin-alpha, and the effects on intestinal morphology, gene expression, apoptosis and other toxicities were assessed. Irinotecan caused a dose-dependent reduction in cell viability that was not prevented by pifithrin-alpha in either cell line. Rats responded to irinotecan with diarrhoea, weight loss, histopathological changes to the small and large intestine, increased crypt apoptosis, and a mild inflammatory response. Pifithrin-alpha reduced severity and duration of intestinal apoptosis; however, it did not significantly affect other parameters including p53 expression. Temporary inhibition of p53 activation does not markedly prevent intestinal cell death or mucositis following irinotecan treatment. Irinotecan may act through upregulation of proapoptotic proteins Bax and Bak to induce cell death.

• Chemotherapy-induced diarrhea is associated with changes in the luminal environment in the DA rat.

  Authors: Andrea M Stringer, Rachel J Gibson, Richard M Logan, Joanne M Bowen, Ann S J Yeoh, Jaimi Burns, Dorothy M K Keefe

  Experimental biology and medicine (Maywood, N.J.). 02/2007; 232(1):96-106.

  The microflora of the gastrointestinal tract (GIT) are a complex ecosystem, performing a number of beneficial functions. Irinotecan causes both early and late diarrhea, the latter possibly caused, inThe microflora of the gastrointestinal tract (GIT) are a complex ecosystem, performing a number of beneficial functions. Irinotecan causes both early and late diarrhea, the latter possibly caused, in part, by changes in the microflora of the GIT. Female DA rats were given atropine subcutaneously, prior to a single 200 mg/kg intraperitoneal dose of irinotecan. Animals were monitored for diarrhea and killed at 30 and 60 mins, 2, 6, 12, 24, 48, and 72 hrs after chemotherapy administration. Control rats received no treatment. Fecal samples and stomach, jejunum, and colon samples were collected and stored at -70 degrees C until required. Standard microbiological culture techniques were used to grow and isolate the flora. Biochemical tests were used to identify the bacteria. The level of growth was noted for relative comparison between time points and graded accordingly. Early diarrhea was observed in the rats from 2-6 hrs after treatment, after which time the diarrhea resolved. Late onset diarrhea was apparent 72 hrs after treatment. Changes were seen in the flora of the stomach, jejunum, colon and feces. The majority of microflora changes were seen 6, 12, and 24 hrs after treatment, with a relative increase or decrease in the presence of bacteria in comparison with control rats. In some rats bacteria were not observed at all time points, and different bacteria not seen in control animals were identified in rats treated with irinotecan. These changes were observed up to 72 hrs after treatment. In conclusion, irinotecan treatment causes changes in the flora of the stomach, jejunum, colon, and feces of rats and is associated with the development of diarrhea. These changes in flora may have systemic effects and in particular may contribute to the development of chemotherapy-induced mucositis.

• Kinetics and regional specificity of irinotecan-induced gene expression in the gastrointestinal tract

  Authors: Joanne M. Bowen, Anna Tsykin, Andrea M. Stringer, Richard M. Logan, Rachel J. Gibson, Dorothy M.K. Keefe

  Toxicology.

  Gastrointestinal toxicity remains a significant and dose-limiting complication of cancer treatment. While the pathophysiology is becoming clearer, considerable gaps in the knowledge remainGastrointestinal toxicity remains a significant and dose-limiting complication of cancer treatment. While the pathophysiology is becoming clearer, considerable gaps in the knowledge remain surrounding the timing and site-specific gene changes which occur in response to insult. As such, this study aimed to assess gene expression profiles in a number of regions along the gastrointestinal tract following treatment with the chemotherapy agent, irinotecan, and correlate them with markers of cell death and tissue damage. Data analysis of microarray results found that genes involved in apoptosis, mitogen activated kinase (MAPK) signalling and inflammation were upregulated within 6 h, while genes involved in cell proliferation, wound healing and blood vessel formation were upregulated at later time points up to 72 h. Cell death was significantly increased at 6 and 24 h, and the stomach showed the lowest severity of overt tissue damage. Real time PCR of MAPK signalling pathway genes found that the jejunum and colon had significantly increased expression in a number of genes at 72 h, where as the stomach was unchanged. These results indicate that overall severity of tissue damage may be determined by precisely timed target gene responses specific to each region. Therapeutic targeting of key gene responses at the appropriate time point may prove to be effective for prevention of chemotherapy-induced gastrointestinal damage.