Abrogating phosphorylation of eIF4B is required for EGFR and mTOR inhibitor synergy in triple-negative breast cancer

Triple-negative breast cancer (TNBC) patients suffer from a highly malignant and aggressive disease. They have a high rate of relapse and often develop resistance to standard chemotherapy. Many TNBCs have elevated epidermal growth factor receptor (EGFR) but are resistant to EGFR inhibitors as monotherapy. In this study, we sought to find a combination therapy that could sensitize TNBC to EGFR inhibitors. Phospho-mass spectrometry was performed on the TNBC cell line, BT20, treated with 0.5 μM gefitinib. Immunoblotting measured protein levels and phosphorylation. Colony formation and growth assays analyzed the treatment on cell proliferation, while MTT assays determined the synergistic effect of inhibitor combination. A Dual-Luciferase reporter gene plasmid measured translation. All statistical analysis was done on CalucuSyn and GraphPad Prism using ANOVAs. Phospho-proteomics identified the mTOR pathway to be of interest in EGFR inhibitor resistance. In our studies, combining gefitinib and temsirolimus decreased cell growth and survival in a synergistic manner. Our data identified eIF4B, as a potentially key fragile point in EGFR and mTOR inhibitor synergy. Decreased eIF4B phosphorylation correlated with drops in growth, viability, clonogenic survival, and cap-dependent translation. Taken together, these data suggest EGFR and mTOR inhibitors abrogate growth, viability, and survival via disruption of eIF4B phosphorylation leading to decreased translation in TNBC cell lines. Further, including an mTOR inhibitor along with an EGFR inhibitor in TNBC with increased EGFR expression should be further explored. Additionally, translational regulation may play an important role in regulating EGFR and mTOR inhibitor synergy and warrant further investigation.     

Association between germline single nucleotide polymorphisms in the PI3K-AKT-mTOR pathway,obesity, and breast cancer disease-free survival

Obesity-related hormones and cytokines alter PI3 K-AKT-mTOR pathway activation in breast tumors contributing to poorer disease-free survival (DFS) and decreased responsiveness to tamoxifen and trastuzumab. We hypothesized that single nucleotide polymorphisms (SNPs) in candidate genes in the PI3 K-AKT-mTOR signaling pathway may act as genetic modifiers of breast cancer DFS. We analyzed the association of 106 tagging SNPs in 13 genes (ADIPOQ, IGF1, INS, IRS1, LEP, LEPR, LEPROT, PIK3CA, PIK3R5, PTEN, TSC1, TSC2, and AKT1) in the P13K-AKT-mTOR pathway with DFS in a sample of 1,019 women with stage I–II breast cancer. SNPs significantly associated with DFS in any genetic model (additive, dominant, or recessive) after correcting for false discovery rate (FDR = 0.10) were included in Cox proportional hazards multivariable analyses. After adjusting for race/ethnicity, age at diagnosis, tumor stage, and treatment, rs1063539 in ADIPOQ, rs11585329 in LEPR, and rs2519757 in TSC1 were associated with improved DFS, and rs1520220 in IGF1 and rs2677760 in PIK3CA were associated with worse DFS. The associations were not significantly modified by the type of systemic treatment received or body mass index. The SNPs were not associated with tumor characteristics such as tumor size, lymph node status, nuclear grade, or hormone receptor status. In this study, germline SNPs in the PI3 K-AKT-mTOR pathway were associated with breast cancer DFS and may be potential prognostic markers. Future studies are needed to replicate our results and to evaluate the relationship between these polymorphisms and activation of the PI3 K-AKT-mTOR pathway in breast tumors.     

Curative-intent stereotactic body radiation therapy for residual breast cancer liver metastasis after systemic chemotherapy

Liver metastases from breast cancer are generally treated with systemic therapy such as chemotherapy or hormonotherapy. However, local treatment options such as resection, radiofrequency ablation (RFA), and radiotherapy can also be considered to treat oligometastases. We report the case of a 45-year-old female treated with stereotactic body radiotherapy (SBRT) after chemotherapy against a solitary liver metastasis from primary breast cancer. A liver metastasis with diameter of 35 mm developed 3.5 years after surgery for primary breast cancer in 2004. Fourteen courses of triweekly docetaxel treatments considerably decreased the metastatic lesion, but there still remained a tiny lesion radiographically. Chemotherapy was stopped because of the side-effects of docetaxel, and then SBRT was selected for additional treatment, aiming at complete cure of metastasis. X-ray irradiation (52.8 Gy/4 fractions) was applied to the remaining metastatic lesion, and magnetic resonance imaging (MRI) showed no evidence of residual tumor 4 months after irradiation. Neither regrowth nor recurrences have been found until now, 24 months after SBRT. SBRT for oligometastases of breast cancer may be one of the possible curative-intent options, being less invasive than surgical resection or RFA.     

Immunopathology of nasal polypi

Thirty patients operated for nasal polypi and 15 age and sex matched controls were taken for study. Estimation of albumin, IgG, IgA, IgM and IgE was done in serum and nasal polyp fluid. Histopathology of polypi was undertaken in order to divide polypi into allergic and inflammatory groups and to study the immunoglobulin profile in these two groups. Allergic polypi were found to be more common than inflammatory polypi. The inflammatory polyp fluid IgA level (208.19 ± 59.33 mg/dl) was significantly raised (p<0.05) as compared to serum (160.58 ±40.28 mg/dl) suggesting the protective role of IgA against entry of antigens. Allergic polyp fluid IgE level (5342.80 ±2540.77 LU, ml.) was roughly twice that of serum (2461.25±1546.25 I.U./ml.) suggesting local production of IgE, rather than that explained by simple filtration process. Also local production of IgE correlated with the tendency to sneeze and was found to be in excess in polypi infiltrated by eosinophils thereby suggesting the role of allergy in production of allergic polypi.     

Immunocytochemical evaluation abl-Gene products in Leukemic Cell Lines

We raised monoclonal antibody (MAb) against a synthetic oligopeptide corresponding to a portion of the predictedv-abl protein sequence (379–390). This MAb reacted with all of theabl-gene products (pl45^c-abl, pl50^c-abl and 210^bcr-abl fused protein) and was not specific for any one of them. Immunocytochemically, we investigated the expression and localization of theabl-gene products in various leukemic cell lines. Positive immunoreactions were observed in Ph¹ positive leukemic cell lines (K562 and KU-812) and erythro-leukemic cell lines (HEL and K3D) and were located on the cell membrane. Electron microscopically, a different distribution pattern was observed among the cell lines: linear and almost even in Ph¹ positive leukemic cell lines, whereas spotted or budding-like in erythroleukemic cell lines. Ph¹ translocation produces p210^nbcr-abl fused protein with not only altered autophosphorylation activities but also altered subcellular distribution patterns.     

Changes in PIK3CA mutation status are not associated with recurrence,metastatic disease or progression in endocrine-treated breast cancer

The phosphatidylinositol-3-kinase pathway plays an important role in proliferation, migration and survival in breast cancer and may play a role in resistance to endocrine therapy. Pathway activation occurs as a result of mutations in PIK3CA or loss of functional PTEN. Matched primary and recurrent samples from 120 breast cancer patients treated with endocrine therapy were profiled with a qPCR-based mutation assay covering eight mutational hotspots in PIK3CA. PTEN was assayed by immunohistochemistry. Samples were well characterized with respect to anatomic location of recurrence (metastatic nodal or local recurrence as opposed to contralateral or ipsilateral new primary cancers). In total, 43 % of patients had at least one PIK3CA mutation at diagnosis, and 41 % had a mutation at the time of recurrence. Only 8 % of patients with local recurrence, metastatic disease or progression on primary endocrine treatment changed their PIK3CA mutation status (four gains, two losses, total 76). The most common changes in PIK3CA mutation status were seen in patients who developed a new cancer either in the treated or contralateral breast (64 %, three gains, four losses, total 11). PIK3CA mutation status does not change in the majority of patients with breast cancer and the acquisition of mutations in PIK3CA is not responsible for the development of endocrine resistance. PTEN loss at diagnosis is associated with a significantly shorter time to progression compared with tumours in which PTEN was retained. These are the most comprehensive data currently available correlating PIK3CA status, site of recurrence and endocrine resistance.     

ADAM17 is associated with EMMPRIN and predicts poor prognosis in patients with uterine cervical carcinoma

Metalloproteinase activities of a disintegrin and metalloproteinase 17 (ADAM17), amphiregulin (AREG), extracellular matrix metalloproteinase inducer (EMMPRIN), and matrix metalloproteinases (MMPs) are involved in tumor biology. In patients with uterine cervical carcinoma, the expression and prognostic significance of ADAM17 remain to be fully elucidated. The expression of ADAM17, AREG, EMMPRIN, phospho-epidermal growth factor receptor (p-EGFR), phospho-extracellular signal-regulated kinase (p-ERK), MMP-2, and MMP-9 was assessed by immunohistochemistry and/or Western blotting from cervical carcinoma cell lines, SiHa and HeLa cells, and cervical carcinoma tissues. AREG activity was measured by ELISA assay. The correlation of ADAM17, AREG, EMMPRIN, and MMP-9 expression with patients’ survival rates was assessed by Kaplan–Meier and Cox regression analyses. RNA interference (RNAi) experiment was performed using small interfering mRNA to ADAM17 and EMMPRIN. ADAM17, EMMPRIN, and MMP-9 protein content was overexpressed in cervical carcinoma tissues compared with normal cervical tissues (P?ADAM17, AREG, EMMPRIN, and MMP-9 was significantly associated with stages, lymph node metastasis, differentiation, and parametrium invasion (P?ADAM17, AREG, EMMPRIN, and MMP-9 was significantly correlated with short progression-free survival and overall survival (P?ADAM17 expression were independent prognostic indicators for cervical cancer. ADAM17 RNAi decreased EMMPRIN, p-EGFR, p-ERK, MMP-2, and MMP-9 proteins in SiHa and HeLa cells. ELISA assay revealed that AREG activity was stimulated by ADAM17 and was reversed by ADAM17 RNAi in SiHa and HeLa cells. Our data suggest that the increased expression of ADAM17 in cervical cancer is significantly associated with aggressive progression and poor prognosis. ADAM17 may be a molecular marker for predicting the progression and prognosis in cervical cancer.     

Triple blockade of HER2 by a cocktail of anti-HER2 scFv antibodies induces high antiproliferative effects in breast cancer cells

Dual therapy targeting human epidermal growth factor receptor 2 (HER2) by pertuzumab and trastuzumab (Herceptin) resulted in the significant survival of patients with HER2-positive breast cancers. However, a number of HER2-overexpressing breast cancers escape from this combination therapy. Due to several advantages of human single-chain antibodies (single chain variable fragments (scFvs)), these molecules were approved as valuable alternatives to entire IgGs for molecular targeting. In this study, our aim was to evaluate the growth inhibitory effects of three novel human anti-HER2 scFvs on breast cancer cells either alone or in combination and to assess their influence on HER2 expression in these cells. Flow cytometry was performed to show the cell binding ability of the scFvs to HER2-overexpressing cell lines, BT-474 and SKBR-3 cells, and HER2 low-expressing cell line, HeLa cells. The antiproliferative effects of the antibodies on the cancer cells were assessed by MTT assay. The amounts of HER2 gene and protein expression after antibody treatments were determined by quantitative real-time PCR and western blotting, respectively. FACS analysis showed that the anti-HER2 scFvs bound to BT-474 and SKBR-3 cells significantly higher than HeLa cells. Growth inhibitory assessment demonstrated that the triple blockade of HER2 by a cocktail of the three anti-HER2 scFvs significantly inhibited the proliferation of the both cancer cells to a greater extent than scFvs individually, in dual combination (scFv-I and scFv-III), and Herceptin. The percentages of growth inhibition of BT-474 and SKBR-3 cells after treatment with the cocktail were up to 77.4 and 76.5 %, respectively. The three scFv antibodies also reduced HER2 expression at both the gene and protein levels individually and in combination. Our results suggest that the cocktail of the three anti-HER2 scFv-I, scFv-II, and scFv-III, which induces high growth inhibition in breast cancer cells and downregulates HER2 gene and protein expression, can be considered as a new alternative for targeting of HER2-positive breast cancers.     

High Sam68 expression predicts poor prognosis in non-small cell lung cancer

Background

The nuclear protein Sam68 has been implicated in the oncogenesis and tumor growth. The aim of this study was to explore the clinical value of Sam68 in patients with non-small cell lung cancer (NSCLC).

Methods

We examined Sam68 expression in 50 NSCLC tissues and matched adjacent noncancerous tissues by quantitative RT-PCR (qRT-PCR) and Western blotting. Furthermore, the Sam68 protein expression was analyzed by immunohistochemistry in 208 NSCLC samples. Kaplan–Meier method and multivariate Cox regression model were used to evaluate the prognostic value of nuclear Sam68 expression in NSCLC for disease survival.

Results

The expression of Sam68 was significantly elevated in NSCLC tissues as compared with adjacent non-cancerous tissues (P < 0.01). The high expression of Sam68 in NSCLC was significantly correlated with lymph node metastasis and tumor TNM stage. Kaplan–Meier survival analysis revealed that high expression of Sam68 correlated with poor prognosis of NSCLC patients (P < 0.01). Multivariate analysis showed that Sam68 expression was an independent prognostic marker for overall survival of NSCLC patients (HR 2.73, 95 % CI 1.549–4.315, P = 0.002).

Conclusion

Our results suggest that high Sam68 expression predicts poor prognosis of NSCLC patients, and Sam68 may be potentially a prognostic biomarker for NSCLC.     

Therapeutic Considerations When Treating HER2-positive Metastatic Breast Cancer

Despite advances in detection and treatment, metastatic breast cancer (MBC) remains the second highest cause of cancer-related death for women in the United States. Human epidermal growth factor receptor-2 (HER2) is amplified in 25–30 % of breast cancers and is associated with aggressive disease and, historically, with poorer outcome. The advent of trastuzumab, a monoclonal antibody to HER2, revolutionized the management of HER2-positive breast cancer (BC) in the metastatic and adjuvant settings. However, relapse despite adjuvant trastuzumab and resistance to trastuzumab in the metastatic setting remain substantial clinical problems for many patients with HER2-positive BC. As such, analyzing the mechanisms of trastuzumab resistance and developing new therapies to overcome it are research priorities. There has been progress, with the approval of three additional HER2-targeted agents in the last six years: lapatinib, pertuzumab, and ado-trastuzumab emtansine (T-DM1). Other HER2-targeted therapies, including neratinib and afatinib, are in clinical development, and trials of novel agents such as heat shock protein-90 (HSP90) inhibitors, phosphatidylinositol-3-kinase (PI3K) inhibitors, and HER2-targeted vaccines, are in progress. In addition to developing new therapies, research is addressing several unique challenges in the management of HER2-positive MBC. In this article, we discuss advances in the treatment of HER2-positive MBC, focusing on novel HER2-targeted therapies and HER2-targeted agents recently approved by the United States Food and Drug Administration (FDA). We also address the management of brain metastases (BM) and hormone receptor (HR)-positive, HER2-positive MBC.     

MGMT gene silencing by promoter hypermethylation in gastric cancer in a high incidence area

Purpose

Inactivation of tumor suppressor and DNA repair genes by promoter hypermethylation does commonly occur in human cancers. O⁶-methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that removes methyl groups as well as larger adducts at the O⁶ position of guanine. In the absence of MGMT activity, O⁶-methylguanine mispairs with thymine during DNA replication, resulting in G:C to A:T transitions. Promoter hypermethylation of the MGMT gene has been observed in various cancers, including gastric cancer. Here, we aimed at assessing the promoter hypermethylation, mutation and expression status of the MGMT gene in patients from a geographic region with a high incidence of gastric cancer (Kashmir, North India) and to investigate their association with various clinicopathological characteristics.

Methods

In this study 82 gastric cancer samples and adjacent normal tissues were included. Mutations in the MGMT gene were detected by single stranded conformational polymorphism (SSCP) analysis and direct sequencing. Methylation-specific polymerase chain reaction (MS-PCR) and Western blot analyses were performed to detect promoter hypermethylation and concomitant (loss of) expression of the MGMT gene.

Results

Promoter hypermethylation of the MGMT gene was found in 52.44 % (43 of 82) of the tumor samples and loss of MGMT protein expression was detected in 45.12 % (37 of 82) of the tumor samples. Hypermethylation and loss of expression were significantly associated with higher tumor grades (moderately/poorly differentiated) (P?P?MGMT hypermethylation and loss of expression were found to be significantly associated with high salt tea consumption (P?Conclusions Our results indicate that MGMT promoter hypermethylation and concomitant loss of MGMT protein expression may play an important role in the development of gastric cancer in the Kashmiri population. High salt tea consumption may be a risk factor.     

Subcutaneous trastuzumab: drug development and current position

HER2-positive breast cancer, accounting for 15 % of the total breast cancer patient population, carries in itself a bad prognosis, which has now become much better after the advent of anti-HER2 drugs. HER2-targeted therapy has significantly improved disease free- and overall survival in HER2-positive breast cancer, and has rendered better disease control both in the early and advanced disease setting. Trastuzumab treatment duration is often prolonged and poses significant time and resource challenges both on the treatment institutions and on the patient. The recent development of a subcutaneous formulation has meant a significant advance in this respect. We review the drug development of the compound and the current evidence on its use.     

Pathological responses and survival of patients with human epidermal growth factor receptor 2-positive breast cancer who received neoadjuvant chemotherapy including trastuzumab

Background

The effectiveness of neoadjuvant chemotherapy is evaluated on the basis of pathological responses and survival outcome, because achievement of a pathological complete response (pCR) is a good predictor of long-term survival. However, few studies have assessed the survival of breast cancer patients who received neoadjuvant chemotherapy including trastuzumab.

Methods

The records of 161 breast cancer patients who received neoadjuvant chemotherapy between January 2006 and December 2011 were retrospectively reviewed. The patients were categorized into 4 subgroups on the basis of the status of the estrogen receptor (ER), the progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). HER2-positive patients received trastuzumab-based regimens. Pathological responses and survival were analyzed on the basis of breast cancer subtypes.

Results

The pCR results obtained were: luminal A and B (ER and/or PR-positive, HER2-negative), 6.3 % (5/79 cases); luminal–HER2 hybrid (ER and/or PR-positive, HER2-positive), 25.0 % (5/20 cases); HER2-enriched (ER and PR-negative, HER2-positive), 63.0 % (17/27 cases); and triple-negative (ER and PR-negative, HER2-negative), 25.7 % (9/35 cases). Achievement of pCR was a good predictor of disease-free survival in the HER2-enriched group. Overall survival of patients with pCR was slightly, but not significantly, better in the HER2-enriched and triple-negative subgroups.

Conclusion

Responses and survival after neoadjuvant chemotherapy including trastuzumab of patients with HER2-positive tumors differed among disease subtypes. Our findings suggest that disease subtype is an important determinant of the efficacy of neoadjuvant chemotherapy.     

CXCL12-CXCR4 axis promotes the natural selection of breast cancer cell metastasis

CXCR4 and its ligand CXCL12 can promote the proliferation, survival, and invasion of cancer cells. They have been shown to play an important role in regulating metastasis of breast cancer to specific organs. High CXCR4 expression was also correlated to poor clinical outcome. Previous study also showed that tumor cells express a high level of CXCR4 and that tumor metastasis target tissues (lung, liver, and bone) express high levels of the ligand CXCL12, allowing tumor cells to directionally migrate to target organs via a CXCL12-CXCR4 chemotactic gradient. However, the exact mechanisms of how CXCR4 and CXCL12 enhance metastasis and/or tumor growth and their full implications on breast cancer progression are unknown. Yet it is likely that chemokine receptor signaling may provide more than just a migrational advantage by also helping the metastasized cells establish and survive in secondary environments. In this study, we investigated CXCR4 and CXCL12 expression in breast cancer and analyzed its association with clinicopathological factors by immunohistochemistry first. Then, we detected the mRNA and protein expression of CXCR4 and CXCL12 in breast cancer cell lines by Western blot and RT-PCR. The MDA-MB-231 has CXCR4 expression and very weak CXCL12 expression. So, we constructed the functional CXCL12 expression in MDA-MB-231 using a gene transfection technique. Further experiments were conducted to evaluate the effect of CXCL12 transfection on the biological behaviors of MDA-MB-231. The cell proliferation of MDA-MB-231–CXCL12 was accessed by MTT assay; the apoptosis was analyzed by an AnnexinV-FITC/propidium iodide double staining of flow cytometry method; and the cell invasive ability was examined by Matrigel invasion assay. Immunohistochemical analysis showed the co-expression of CXCR4 and CXCL12 correlated with lymph node metastasis and TNM stage (p?CXCL12 and its sole ligand CXCR4 play important role in the malignance of breast cancer. To gain a deeper insight into it, we picked CXCR4-expressing cells MDA-MB-231 to be transfected with CXCL12 stably. The decreased cellular proliferation, increased apoptosis, and invasive ability were found in MDA-MB-231 with successful CXCL12 transfection (p?CXCL12-CXCR4 axis correlated tightly with breast cancer metastasis. CXCL12-CXCR4 axis can increase the invasion and apoptosis of MDA-MB-231 simultaneously. These data strongly support the hypothesis that CXCL12-CXCR4 axis promotes the natural selection of breast cancer cell metastasis. Our findings could have significant implications in terms of breast cancer aggressiveness and the effectiveness of targeting the receptors and downstream signaling pathways for the treatment of breast cancer.     

Comparison of dual-color in-situ hybridization and fluorescence in-situ hybridization in HER2 gene amplification in breast cancer

Background

HER2 is a prognostic factor in breast cancer, and is predictive of the effects of HER2-targeted drugs. HER2 tests are essential in invasive and metastatic breast cancer. Dual-color in-situ hybridization (DISH) is a novel genetic test, and we investigated its utility in HER2 testing in breast cancer.

Methods

Using DISH and two FISH methods (FISH method 1, FISH method 2) with representative slices of surgical specimens from 134 invasive breast cancer patients, we performed HER2 gene testing and compared the results for HER2 gene/CEP17 signal ratio and HER2 gene diagnosis.

Results

Of 134 patients, either the HER2 gene or the CEP17 signal could not be counted in 2 patients by DISH, in 1 patient by FISH method 1, and in 1 patient by FISH method 2. HER2 gene/CEP17 signal ratios were strongly correlated in DISH and FISH method 1 (R = 0.85, P < 0.05). Agreement of DISH and FISH method 1 for HER2 gene diagnosis was 98.5 % for all patients, irrespective of gene amplification (κ = 0.97). HER2 gene/CEP17 signal ratios were strongly correlated in DISH and FISH method 2 (R = 0.87, P < 0.05). Agreement of DISH and FISH method 2 for HER2 gene diagnosis was 94.1 % for gene amplification patients, 98.4 % for gene non-amplification patients, and 96.2 % for all patients (κ = 0.92).

Conclusions

DISH is useful for HER2 gene testing in breast cancer, and is recommended as a new option for assessing HER2 status.     

Recent advances in radiation oncology: intensity-modulated radiotherapy,a clinical perspective

Radiotherapy plays an important role in the treatment of various malignancies, and intensity-modulated radiotherapy (IMRT) is an attractive option because it can deliver precise conformal radiation doses to the target while minimizing the dose to adjacent normal tissues. IMRT provides a highly conformal dose distribution by modulating the intensity of the radiation beam. A number of malignancies have been targeted by IMRT; this work reviews published data on the major disease sites treated with IMRT. The dosimetric advantage of IMRT has resulted in the significant reduction of adverse effects in some tumors. However, there are few clinical trials comparing IMRT and three-dimensional conformal radiotherapy (3D-CRT), and no definite increase in survival or the loco-regional control rate by IMRT has been demonstrated in many malignancies. IMRT also requires greater time and resources to complete compared to 3D-CRT. In addition, the cost–effectiveness of IMRT versus 3D-CRT has not yet been established.     

Molecular Heterogeneity of Triple-Negative Breast Cancer

Triple-negative breast cancers (TNBCs) are a group of aggressive breast cancers with a greater incidence of relapse, stage-for-stage, than ER/PR-positive and HER2-positive breast cancers, despite optimum loco-regional and systemic therapy. To date, no single targeted therapy has been approved for treatment of TNBC, and cytotoxic chemotherapy remains the standard systemic treatment. Recently, gene expression analysis identified six distinct TNBC subtypes, each with unique biology. In this review we discuss current and forthcoming therapeutic strategies and novel approaches to targeted treatment of these TNBC subtypes.     

Determining the mechanisms of lapatinib-induced diarrhoea using a rat model

Introduction

Diarrhoea caused by treatment with receptor tyrosine kinase inhibitors (TKI) targeting Epidermal Growth Factor Receptors (EGFR) is an important clinical toxicity in oncology that remains poorly understood. This study aimed to identify histological and molecular changes within the intestine following lapatinib to elucidate mechanisms of diarrhoea related to treatment with this dual EGFR TKI.

Methods and materials

Male albino Wistar rats were orally gavaged lapatinib at 100, 240 or 500 mg/kg daily for 4 weeks and assessed for indicators of gastrointestinal injury at the end of each week. Lapatinib in combination with weekly paclitaxel (9 mg/kg i.p.) was also assessed for cumulative injury. At each time point, blood was collected for biochemical analysis. Sections or jejunum and colon were also collected and underwent immunohistochemistry and RT-PCR to detect markers of EGFR pathway signalling, and morphometric analysis to assess changes in mucosal architecture.

Results

Lapatinib (with or without paclitaxel co-treatment) caused dose-dependent changes in crypt length, mitotic rate and goblet cell morphology. Jejunal crypt expression of EGFR and ErbB2 were decreased, whilst no changes in Erk1/2 were observed. Markers of apoptosis (caspase-3) and proliferation (Ki-67) were only significantly altered in rats treated with both lapatinib and paclitaxel.

Conclusions

In our novel rat model of lapatinib-induced diarrhoea we have shown that changes in small intestinal morphometry and expression of EGFR are associated with diarrhoea. Further research is required to test intervention agents for the prevention of diarrhoea.