The ubiquitin-proteasome system and signal transduction pathways regulating Epithelial Mesenchymal transition of cancer.

Epithelial to Mesenchymal transition (EMT) in cancer, a process permitting cancer cells to become mobile and metastatic, has a signaling hardwire forged from development. Multiple signaling pathways that regulate carcinogenesis enabling characteristics in neoplastic cells such as proliferation, resistance to apoptosis and angiogenesis are also the main players in EMT. These pathways, as almost all cellular processes, are in their turn regulated by ubiquitination and the Ubiquitin-Proteasome System (UPS). Ubiquitination is the covalent link of target proteins with the small protein ubiquitin and serves as a signal to target protein degradation by the proteasome or to other outcomes such as endocytosis, degradation by the lysosome or specification of cellular localization. This paper reviews signal transduction pathways regulating EMT and being regulated by ubiquitination

Pancreatic adenocarcinomas without KRAS, TP53, CDKN2A and SMAD4 mutations and CDKN2A/CDKN2B copy number alterations: a review of the genomic landscape to unveil therapeutic avenues.

Pancreatic adenocarcinoma is one of the cancers with the worst prognosis. The current treatment paradigm based on combination chemotherapy has improved survival over the last decade, but the disease is still fatal in most cases. New therapies exploiting the increasing understanding of the molecular pathology of the disease are needed. Although the disease presents with few recurrent molecular alterations, these represent opportunities for targeted treatments to be developed. However, a minority of cases are devoid of these common alterations. A description of the molecular landscape of this sub-set of pancreatic adenocarcinoma could uncover other molecular lesions present in them that could serve as therapeutic targets. The sub-set of pancreatic cancers without the common alterations in KRAS, TP53, CDKN2A and SMAD4 has been examined from published and publicly available pancreatic cancer cohorts for determination of their clinical and molecular characteristics. The cBioportal platform was used for this evaluation and the OncoKB knowledgebase was used for determination of the functional significance of discovered mutations. About 5% to 10% of pancreatic adenocarcinomas present without the usual molecular alterations that characterize the disease. These cases tend to be genomically stable and have low prevalence of microsatellite or chromosome instability. Molecular alterations that are observed in pancreatic cancers in lower frequencies than the four most prevalent alterations, such as DNA Damage Response and epigenetic modifier mutations, are still observed in the sub-set without the common alterations and may be pathogenically relevant. Despite the absence of most frequent pancreatic cancer alterations in a sub-set of pancreatic adenocarcinomas, this sub-set possesses other alterations in frequencies similar to the rest of pancreatic cancers. Putative targeting of alterations present is discussed and can serve as the basis for targeted therapies development

Thrombocytosis as a prognostic marker in stage III and IV serous ovarian cancer.

OBJECTIVE: Thrombocytosis is an adverse prognostic factor in many types of cancer. We investigated if pre-treatment increased platelet counts provide prognostic information specifically in patients with stage III and IV serous ovarian cancer which is the most common clinical presentation of ovarian cancer. METHODS: Platelet number on diagnosis of stage III and IV serous ovarian adenocarcinoma was evaluated in 91 patients for whom there were complete follow-up data on progression and survival. Survival and progression free survival of patients with normal platelet counts (150-350 ×10(9)/L) was compared with that of patients with thrombocytosis (>350×10(9)/L) by χ(2) and logrank tests. RESULTS: The median age of the patients was 66 years-old. From the 91 patients, 52 (57.1%) had normal platelet counts (median, 273×10(9)/L; range, 153-350) at diagnosis of their disease and 39 patients (42.9%) had thrombocytosis (median, 463×10(9)/L; range, 354-631). In the group of patients with normal platelet counts, 24 of the 52 patients had died with a median survival of 43 months (range, 3-100). In the group of patients with thrombocytosis, 24 of the 39 patients had died with a median survival of 23 months (range, 4-79). In the entire group of 91 patients there was a statistically significant difference of the overall survival and progression-free survival between the two groups (logrank test P=0.02 and P=0.007, respectively). CONCLUSION: In this retrospective analysis of stage III and IV ovarian cancer patients, thrombocytosis at the time of diagnosis had prognostic value regarding overall survival and progression-free survival

Homologous Recombination Defects and Mutations in DNA Damage Response (DDR) Genes Besides BRCA1 and BRCA2 as Breast Cancer Biomarkers for PARP Inhibitors and Other DDR Targeting Therapies.

Homologous recombination repair (HRR) is the cellular mechanism for error-free repair of double strand DNA (dsDNA) breaks. Cancer cells with mutations in both alleles of genes encoding for proteins involved in HRR, such as BRCA1 and BRCA2, have defects in the repair process. As a result, these cells repair dsDNA breaks with alternative mechanisms, such as non-homologous end joining. In breast cancers with germline mutations in BRCA1 and BRCA2 genes, HRR defects result in sensitivity to PARP inhibitors, drugs that interfere with the function of PARP enzyme and promote trapping of the enzyme on DNA and stalling of the process of repairing single strand breaks. HRR defects also lead to sensitivity to DNA damaging chemotherapy due to the inability of cells to repair chemotherapy induced DNA lesions. Besides germline mutations in BRCA1 and BRCA2, somatic mutations in these genes or germline and somatic mutations or other genetic and epigenetic alterations of other genes involved in homologous recombination (HR) may produce HRR defects leading to sensitivity to PARP inhibitors. However, studies are less conclusive, a fact that may relate to the common lack of bi-allelic loss of function in these cases, as opposed to cancers with germline BRCA1 or BRCA2 defects that usually acquire bi-allelic loss of function. In addition, there is heterogeneity between the different HRR genes and the severity of the resulting HRR defects, as measured by HR defect assays. This review article examines the landscape of HRR gene mutations in breast cancer and the possible therapeutic implications of HRR defects other than germline BRCA1 and BRCA2 mutations for targeted therapies. Identification of a wider range of breast cancers with HRR defects may expand the subset of patients that derive benefit from PARP inhibitors and other DDR-targeting drugs in the clinic

Vinorelbine with or without Trastuzumab in Metastatic Breast Cancer: A Retrospective Single Institution Series

Background. We report our experience with vinorelbine, a widely used chemotherapeutic, in unselected metastatic breast cancer patients treated in clinical routine. Patients and Methods. The data of all patients with metastatic breast cancer receiving vinorelbine with or without trastuzumab during a six year period were reviewed. Patients received vinorelbine intravenous 25-30 mg/m(2) or 60-80 mg/m(2) orally in days 1 and 8 of a 21 day cycle. Results. Eighty-seven women were included. Sixty-two patients received vinorelbine alone and 25 patients received vinorelbine in combination with trastuzumab. In 67 patients this was the first line treatment for metastatic disease and in 20 patients it was 2nd or later line of treatment. The median TTP was six months (range: 1-45). The median overall survival was 11.5 months (range: 1-83). Seventy patients were evaluable for response. In patients receiving first line treatment 44.4% had a response while in the second and subsequent lines setting 12.5% of patients responded (P = 0.001). Objective response was obtained in 63.6% of patients receiving concomitant trastuzumab and in 25% of patients receiving vinorelbine alone (P = 0.0002). Conclusion. This study confirms a high disease control rate. Response rate and TTP were superior in first line treatment compared to subsequent lines

Epithelial to mesenchymal transition in the pathogenesis of uterine malignant mixed Müllerian tumours: the role of ubiquitin proteasome system and therapeutic opportunities.

Malignant mixed Müllerian tumours (malignant mixed mesodermal tumours, MMMT) of the uterus are metaplastic carcinomas with a sarcomatous component and thus they are also called carcinosarcomas. It has now been accepted that the sarcomatous component is derived from epithelial elements that have undergone metaplasia. The process that produces this metaplasia is epithelial to mesenchymal transition (EMT), which has recently been described as a neoplasia-associated programme shared with embryonic development and enabling neoplastic cells to move and metastasise. The ubiquitin proteasome system (UPS) regulates the turnover and functions of hundreds of cellular proteins. It plays important roles in EMT by being involved in the regulation of several pathways participating in the execution of this metastasis-associated programme. In this review the specifi c role of UPS in EMT of MMMT is discussed and therapeutic opportunities from UPS manipulations are proposed

Peroxisome proliferator-activated receptor gamma and regulations by the ubiquitin-proteasome system in pancreatic cancer.

Pancreatic cancer is one of the most lethal forms of human cancer. Although progress in oncology has improved outcomes in many forms of cancer, little progress has been made in pancreatic carcinoma and the prognosis of this malignancy remains grim. Several molecular abnormalities often present in pancreatic cancer have been defined and include mutations in K-ras, p53, p16, and DPC4 genes. Nuclear receptor Peroxisome Proliferator-Activated Receptor gamma (PPARγ) has a role in many carcinomas and has been found to be overexpressed in pancreatic cancer. It plays generally a tumor suppressor role antagonizing proteins promoting carcinogenesis such as NF-κB and TGFβ. Regulation of pathways involved in pancreatic carcinogenesis is effectuated by the Ubiquitin Proteasome System (UPS). This paper will examine PPARγ in pancreatic cancer, the regulation of this nuclear receptor by the UPS, and their relationship to other pathways important in pancreatic carcinogenesis

The ubiquitin-proteasome system in glioma cell cycle control.

A major determinant of cell fate is regulation of cell cycle. Tight regulation of this process is lost during the course of development and progression of various tumors. The ubiquitin-proteasome system (UPS) constitutes a universal protein degradation pathway, essential for the consistent recycling of a plethora of proteins with distinct structural and functional roles within the cell, including cell cycle regulation. High grade tumors, such as glioblastomas have an inherent potential of escaping cell cycle control mechanisms and are often refractory to conventional treatment. Here, we review the association of UPS with several UPS-targeted proteins and pathways involved in regulation of the cell cycle in malignant gliomas, and discuss the potential role of UPS inhibitors in reinstitution of cell cycle control

The Future of ER+/HER2- Metastatic Breast Cancer Therapy: Beyond PI3K Inhibitors.

Most breast cancers express the estrogen receptor (ER) receptor and are negative for the human epidermal growth factor receptor 2 (HER2) receptor. ER+/HER2- cancers are treated with hormone-based therapies in the adjuvant setting and derive significant survival benefit from these therapies in the metastatic setting. However, hormone resistance develops in most metastatic patients. An increased understanding of the biology of ER+/HER2- breast cancers has led to the development of new therapies for this disease including CDK4/6 inhibitors and PI3K inhibitors. Several other neoplastic processes are targeted by novel drugs in clinical development, addressing cancer vulnerabilities. These include newer ways to block the ER and targeting the HER2 receptors in ER+/HER2- cancers expressing HER2 in low levels not qualifying for clinical positivity. In addition, promising therapeutic options include targeting other surface receptors or their downstream pathways, as well as targeting the apoptotic machinery and boosting the immune response which is initially insufficient in these cancers. A selection of new drugs in advanced development for ER+/HER2- breast cancer will be discussed in this review

Combinations of vascular endothelial growth factor pathway inhibitors with metronomic chemotherapy: Rational and current status.

Chemotherapy given in a metronomic manner can be administered with less adverse effects which are common with conventional schedules such as myelotoxicity and gastrointestinal toxicity and thus may be appropriate for older patients and patients with decreased performance status. Efficacy has been observed in several settings. An opportunity to improve the efficacy of metronomic schedules without significantly increasing toxicity presents with the addition of anti-angiogenic targeted treatments. These combinations rational stems from the understanding of the importance of angiogenesis in the mechanism of action of metronomic chemotherapy which may be augmented by specific targeting of the vascular endothelial growth factor (VEGF) pathway by antibodies or small tyrosine kinase inhibitors. Combinations of metronomic chemotherapy schedules with VEGF pathway targeting drugs will be discussed in this paper