Toni Ibrahim

Direct targeting of Sec23a by miR-200s influences cancer cell secretome and promotes metastatic colonization

Although the role of miR-200s in regulating E-cadherin expression and epithelial-to-mesenchymal transition is well established, their influence on metastatic colonization remains controversial. Here we have used clinical and experimental models of breast cancer metastasis to discover a pro-metastatic role of miR-200s that goes beyond their regulation of E-cadherin and epithelial phenotype. Overexpression of miR-200s is associated with increased risk of metastasis in breast cancer and promotes metastatic colonization in mouse models, phenotypes that cannot be recapitulated by E-cadherin expression alone. Genomic and proteomic analyses revealed global shifts in gene expression upon miR-200 overexpression toward that of highly metastatic cells. miR-200s promote metastatic colonization partly through direct targeting of Sec23a, which mediates secretion of metastasis-suppressive proteins, including Igfbp4 and Tinagl1, as validated by functional and clinical correlation studies. Overall, these findings suggest a pleiotropic role of miR-200s in promoting metastatic colonization by influencing E-cadherin–dependent epithelial traits and Sec23a-mediated tumor cell secretome.

miR-126 and miR-126 * repress recruitment of mesenchymal stem cells and inflammatory monocytes to inhibit breast cancer metastasis

The tumour stroma is an active participant during cancer progression. Stromal cells promote tumour progression and metastasis through multiple mechanisms including enhancing tumour invasiveness and angiogenesis, and suppressing immune surveillance. We report here that miR-126/miR-126*, a microRNA pair derived from a single precursor, independently suppress the sequential recruitment of mesenchymal stem cells and inflammatory monocytes into the tumour stroma to inhibit lung metastasis by breast tumour cells in a mouse xenograft model. miR-126/miR-126* directly inhibit stromal cell-derived factor-1 alpha (SDF-1α) expression, and indirectly suppress the expression of chemokine (C–C motif) ligand 2 (Ccl2) by cancer cells in an SDF-1α-dependent manner. miR-126/miR-126* expression is downregulated in cancer cells by promoter methylation of their host gene Egfl7. These findings determine how this microRNA pair alters the composition of the primary tumour microenvironment to favour breast cancer metastasis, and demonstrate a correlation between miR-126/126* downregulation and poor metastasis-free survival of breast cancer patients.

Tumor-Induced Osteoclast miRNA Changes as Regulators and Biomarkers of Osteolytic Bone Metastasis

Understanding the mechanism by which tumor cells influence osteoclast differentiation is crucial for improving treatment of osteolytic metastasis. Here, we report broad microRNA (miRNA) expression changes in differentiating osteoclasts after exposure to tumor-conditioned media, in part through activation of NFκB signaling by soluble intracellular adhesion molecule (sICAM1) secreted from bone-metastatic cancer cells. Ectopic expression of multiple miRNAs downregulated during osteoclastogenesis suppresses osteoclast differentiation by targeting important osteoclast genes. Intravenous delivery of these miRNAs in vivo inhibits osteoclast activity and reduces osteolytic bone metastasis. Importantly, serum levels of sICAM1 and two osteoclast miRNAs, miR-16 and miR-378, which are elevated in osteoclast differentiation, correlate with bone metastasis burden. These findings establish miRNAs as potential therapeutic targets and clinical biomarkers of bone metastasis.

Elf5 inhibits the epithelial–mesenchymal transition in mammary gland development and breast cancer metastasis by transcriptionally repressing Snail2

The epithelial–mesenchymal transition (EMT) is a complex process that occurs during organogenesis and in cancer metastasis. Despite recent progress, the molecular pathways connecting the physiological and pathological functions of EMT need to be better defined. Here we show that the transcription factor Elf5, a key regulator of mammary gland alveologenesis, controls EMT in both mammary gland development and metastasis. We uncovered this role for Elf5 through analyses of Elf5 conditional knockout animals, various in vitro and in vivo models of EMT and metastasis, an MMTV-neu transgenic model of mammary tumour progression and clinical breast cancer samples. Furthermore, we demonstrate that Elf5 suppresses EMT by directly repressing the transcription of Snail2, a master regulator of mammary stem cells and a known inducer of EMT. These findings establish Elf5 not only as a key cell lineage regulator during normal mammary gland development, but also as a suppressor of EMT and metastasis in breast cancer.

Pathogenesis of osteoblastic bone metastases from prostate cancer.

Prostate cancer is the second leading cause of cancer‐related death in men. A typical feature of this disease is its ability to metastasize to bone. It is mainly osteosclerotic, and is caused by a relative excess of osteoblast activity, leading to an abnormal bone formation. Bone metastases are the result of a complex series of steps that are not yet fully understood and depend on dynamic crosstalk between metastatic cancer cells, cellular components of the bone marrow microenvironment, and bone matrix (osteoblasts and osteoclasts). Prostate cancer cells from primary tissue undergo an epithelial‐mesenchymal transition to disseminate and acquire a bone‐like phenotype to metastasize in bone tissue. This review discusses the biological processes and the molecules involved in the progression of bone metastases. Here we focus on the routes of osteoblast differentiation and activation, the crosstalk between bone cells and tumor cells, and the molecules involved in these processes that are expressed by both osteoblasts and tumor cells. Furthermore, this review deals with the recently elucidated role of osteoclasts in prostate cancer bone metastases. Certainly, to better understand the underlying mechanisms of bone metastasis and so improve targeted bone therapies, further studies are warranted to shed light on the probable role of the premetastatic niche and the involvement of cancer stem cells. Cancer 2010.

Efficacy and safety of 12-weekly versus 4-weekly zoledronic acid for prolonged treatment of patients with bone metastases from breast cancer (ZOOM): a phase 3, open-label, randomised, non-inferiority trial.

BACKGROUND Zoledronic acid reduces skeletal-related events in patients with breast cancer, but concerns have been raised about prolonged monthly administration. We assessed the efficacy and safety of a reduced dosing frequency of zoledronic acid in women treated previously with monthly zoledronic acid. METHODS We did this non-inferiority, phase 3 trial in 62 centres in Italy. We enrolled patients with breast cancer who had one or more bone metastases and had completed 12-15 months of monthly treatment with zoledronic acid. Patients were randomly assigned with a permutated block (size four to eight) random list stratified by centre in a 1:1 ratio to zoledronic acid 4 mg once every 12 weeks or once every 4 weeks, and followed up for at least 1 year. Neither patients nor investigators were masked to treatment allocation. The primary outcome was skeletal morbidity rate (skeletal-related events per patient per year) in the intention-to-treat population. We used a non-inferiority margin of 0.19. The trial is registered with EudraCT, number 2005-004942-15. FINDINGS We screened 430 patients and enrolled 425, of whom 209 were assigned to the 12-week group and 216 to the 4-week group. The skeletal morbidity rate was 0.26 (95% CI 0.15-0.37) in the 12-week group versus 0.22 (0.14-0.29) in the 4-week group. The between-group difference was 0.04 and the upper limit of one-tailed 97.5% CI was 0.17, which is lower than the non-inferiority margin. The most common grade 3-4 adverse events were bone pain (56 [27%] patients in the 12-week group vs 65 [30%] in the 4-week group), nausea (24 [11%] vs 33 [15%]), and asthenia (18 [9%] vs 33 [15%]). Renal adverse events occurred in one patient (<1%) in the 12-week group versus two (1%) in the 4-week group. One patient (<1%) in the 4-week group had grade 1 acute renal failure. Osteonecrosis of the jaw occurred in four patients in the 12-week group versus three in the 4-week group. No treatment-related deaths were reported. Median N-terminal telopeptide concentration changed from baseline more in the 12-week group than in the 4-week group after 12 months (12.2% vs 0.0%; p=0.011). INTERPRETATION Our results raise the possibility of decreasing administration of zoledronic acid to a 12-weekly regimen to reduce exposure during the second year, while maintaining its therapeutic effects. However, the effects on N-terminal telopeptide should be investigated further before changing current practice. FUNDING Novartis Farma.

ΔNp63 promotes stem cell activity in mammary gland development and basal-like breast cancer by enhancing Fzd7 expression and Wnt signalling

Emerging evidence suggests that cancer is populated and maintained by tumour-initiating cells (TICs) with stem-like properties similar to those of adult tissue stem cells. Despite recent advances, the molecular regulatory mechanisms that may be shared between normal and malignant stem cells remain poorly understood. Here we show that the ΔNp63 isoform of the Trp63 transcription factor promotes normal mammary stem cell (MaSC) activity by increasing the expression of the Wnt receptor Fzd7, thereby enhancing Wnt signalling. Importantly, Fzd7-dependent enhancement of Wnt signalling by ΔNp63 also governs tumour-initiating activity of the basal subtype of breast cancer. These findings establish ΔNp63 as a key regulator of stem cells in both normal and malignant mammary tissues and provide direct evidence that breast cancer TICs and normal MaSCs share common regulatory mechanisms.

Natural history of bone metastasis in colorectal cancer: final results of a large Italian bone metastases study

BACKGROUND Data are limited regarding bone metastases from colorectal cancer (CRC). The objective of this study was to survey the natural history of bone metastasis in CRC. PATIENTS AND METHODS This retrospective, multicenter, observational study of 264 patients with CRC involving bone examined cancer treatments, bone metastases characteristics, skeletal-related event (SRE) type and frequency, zoledronic acid therapy, and disease outcomes. RESULTS Most patients with bone metastases had pathologic T3/4 disease at CRC diagnosis. The spine was the most common site involved (65%), followed by hip/pelvis (34%), long bones (26%), and other sites (17%). Median time from CRC diagnosis to bone metastases was 11.00 months; median time to first SRE thereafter was 2.00 months. Radiation and pathologic fractures affected 45% and 10% of patients, respectively; 32% of patients had no reported SREs. Patients survived for a median of 7.00 months after bone metastases diagnosis; SREs did not significantly affect survival. Subgroup analyses revealed that zoledronic acid significantly prolonged median time to first SRE (2.00 months versus 1.00 month, respectively, P=0.009) and produced a trend toward improved overall survival versus no zoledronic acid. CONCLUSION This study illustrates the burden of bone metastases from CRC and supports the use of zoledronic acid in this setting.

Osteonecrosis of the Jaw in Patients with Bone Metastases Treated with Bisphosphonates: A Retrospective Study

OBJECTIVE Bone metastases are a major cause of morbidity in cancer patients. Treatment includes bisphosphonates, which are also associated with avascular osteonecrosis of the jaw (ONJ). Our aim was to evaluate the correlation between bisphosphonates and ONJ. PATIENTS AND METHODS Of the 539 patients with bone metastases treated in our department from June 2002 to December 2006 with i.v. bisphosphonates, eight (1.5%) developed ONJ. RESULTS The eight patients with ONJ had all been given zoledronic acid, and two had also been treated with pamidronic acid. In four of the patients, ONJ was diagnosed during treatment, while in the remaining four it was diagnosed several months after therapy with bisphosphonates had ended. Six of these patients received local noninvasive treatment, of whom five progressed. Two showed apparent autolimitation of the disease. The remaining two patients underwent surgical resection and currently show no signs of relapse. All eight ONJ patients presented with various concomitant risk factors such as paradontopathy, dental extraction, or spontaneous avulsion. CONCLUSIONS Our results show that ONJ can appear months after interruption of treatment and that a surgical approach can be used in suitable cases. Closer cooperation is needed among specialists to define guidelines for the prevention of ONJ in patients with bone metastases.

Trastuzumab-induced cardiotoxicity in early breast cancer patients: a retrospective study of possible risk and protective factors

Objective Although adjuvant trastuzumab improves survival in patients with HER2-positive early breast cancer, there is growing concern about the long-term effect of trastuzumab-induced cardiotoxicity (TIC). We retrospectively assessed the incidence of TIC and heart failure (HF) to identify possible risk and protective factors. Design Retrospective study. Setting Institute for Cancer Research and Treatment, Medical Oncology Department. Patients Consecutive patients who started adjuvant trastuzumab between 2007 and 2010. Main outcome Measures TIC was defined as an absolute left ventricular ejection fraction (LVEF) decrease ≥15 points from baseline or a LVEF<50%. Logistic regression was used to estimate OR and their 95% CI in order to evaluate the risk of TIC, considering potential cardiac risk factors (hypertension, hypercholesterolaemia, diabetes mellitus, smoke, cardiac ischaemia and previous chest radiotherapy) and protective factors (β-blockers, ACE inhibitors and/or angiotensin receptor blockers). Results Among 179 patients, 78 cases of TIC (44%, 95% CI 37% to 51%) and four cases of HF (2%, 95% CI 0% to 4%) were reported. 14 patients stopped trastuzumab as a result of TIC. None of the cardiac risk factors or concomitant cardiovascular medications altered the risk of TIC. A previous cumulative dose >240 mg/m2 of doxorubicin or >500 mg/m2 of epirubicin increased the risk of TIC compared with lower doses (OR 3.07; 95% CI 1.29 to 7.27, p=0.0011). Conclusions TIC is a frequent, albeit generally mild, adverse event in clinical practice. Further studies are warranted to better define the risk of and protective factors for TIC.