Platelets are formed from mature megakaryocytes (MKs) and arise from the development of long and thin cytoplasmic extensions called proplatelets. After platelet release, the senescent MKs (nucleus surrounded by some cytoplasm) undergo cell death by apoptosis. To explore the precise role of apoptosis in proplatelet formation, we grew human MKs from CD34(+) cells and assessed the possible role of caspases. Proteolytic maturation of procaspase-3 and procaspase-9 was detected by immunoblots in maturing MKs as well as in proplatelet-bearing MKs and senescent MKs. Cleavage of caspase substrates such as gelsolin or poly adenosine diphosphate (ADP)-ribose polymerase (PARP) was also detected. Interestingly, activated forms of caspase-3 were detected in maturing MKs, before proplatelet formation, with a punctuate cytoplasmic distribution, whereas a diffuse staining pattern was seen in senescent and apoptotic MKs. This localized activation of caspase-3 was associated with a mitochondrial membrane permeabilization as assessed by the release of cytochrome c, suggesting an activation of the intrinsic pathway. Moreover, these MKs with localized activated caspase-3 had no detectable DNA fragmentation. In contrast, when apoptosis was induced by staurosporine, diffuse caspase activation was seen; these MKs had signs of DNA fragmentation, and no proplatelet formation occurred. The pan-caspase inhibitor z-VAD.fmk as well as more specific inhibitors of caspase-3 and caspase-9 blocked proplatelet formation, whereas an inhibitor of calpeptin had no effect. Overexpression of Bcl-2 also inhibited proplatelet formation in maturing MKs. Thus, localized caspase activation is causal to proplatelet formation. We conclude that proplatelet formation is regulated by a caspase activation limited to only some cellular compartments.

Purpose: To evaluate the risk of locoregional recurrence (LRR) associated with locoregional treatment of women with primary breast cancer tumors negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (triple-negative breast cancer [TNBC]). Patients and Methods: Patients diagnosed with TNBC were identified from a cancer registry in a single institution (n=768). LRR-free survival was estimated using Kaplan-Meier analysis. The Cox proportional hazards regression model was used to determine risk of LRR on the basis of locoregional management: breast-conserving therapy (BCT; ie, lumpectomy and adjuvant radiation therapy [RT]) and modified radical mastectomy (MRM) in the TNBC population and T1-2N0 subgroup. Results: At a median follow-up of 7.2 years, 77 patients (10%) with TNBC developed LRR. Five-year LRR-free survival was 94%, 85%, and 87% in the BCT, MRM, and MRM + RT groups, respectively (P < .001). In multivariate analysis, MRM (compared with BCT), lymphovascular invasion and lymph node positivity were associated with increased LRR. Conversely, adjuvant chemotherapy was associated with decreased risk of LRR. For patients with T1-2N0 tumors, 5-year LRR-free survival was 96% and 90% in the BCT and MRM groups, respectively (P =.027), and MRM was the only independent prognostic factor associated with increased LRR compared with BCT (hazard ratio, 2.53; 95% CI, 1.12 to 5.75; P= .0264). Conclusion: Women with T1-2N0 TNBC treated with MRM without RT have a significant increased risk of LRR compared with those treated with BCT. Prospective studies are warranted to investigate the benefit of adjuvant RT after MRM in TNBC.

The pathophysiology of microthrombocytopenia in the Wiskott-Aldrich syndrome (WAS) and its milder form, X-linked thrombocytopenia (XLT), is unclear. Although quantitative defects are correctable by splenectomy, residual platelet abnormalities are suggestive of intrinsic disturbances of production. In contrast to human patients, murine models of WASp deficiency exhibit only mild thrombocytopenia, and platelets are of normal size. Here, we have identified a critical role for WASp during murine platelet biogenesis. By electron microscopy, WASp-deficient MKs appeared to have shed platelets ectopically within the bone marrow space. WASp-deficient megakaryocytes (MKs) also displayed defects in response to fibrillar collagen I (CI) in vitro, the major matrix component of bone. These included a loss of normal CI receptor (α2β1 integrin)-mediated inhibition of proplatelet formation, a marked abrogation of SDF-1-induced chemotactic migration of CD41⁺ MKs adherent to CI, and an almost complete lack of actin-rich podosomes, normally induced by interaction between CI and its receptors GPVI or α2β1 integrin. These findings highlight the central and highly specialized role of WASp in MKs during platelet biogenesis, and may provide a mechanism for the mild thrombocytopenia observed in WASp-deficient mice. In addition, they suggest a novel explanation for some of the platelet abnormalities characteristic of patients with WAS. (Blood. 2006;108:134-140)

Radiomics analysis has had remarkable progress along with advances in medical imaging, most notability in central nervous system malignancies. Radiomics refers to the extraction of a large number of quantitative features that describe the intensity, texture and geometrical characteristics attributed to the tumor radiographic data. These features have been used to build predictive models for diagnosis, prognosis, and therapeutic response. Such models are being combined with clinical, biological, genetics and proteomic features to enhance reproducibility. Broadly, the four steps necessary for radiomic analysis are: (1) image acquisition, (2) segmentation or labeling, (3) feature extraction, and (4) statistical analysis. Major methodological challenges remain prior to clinical implementation. Essential steps include: adoption of an optimized standard imaging process, establishing a common criterion for performing segmentation, fully automated extraction of radiomic features without redundancy, and robust statistical modeling validated in the prospective setting. This review walks through these steps in detail, as it pertains to high grade gliomas. The impact on precision medicine will be discussed, as well as the challenges facing clinical implementation of radiomic in the current management of glioblastoma.

Glioma are the most common type of malignant brain tumor, with glioblastoma (GBM) representing the most common and most lethal type of glioma. Surgical resection followed by radiotherapy and chemotherapy using the alkylating agent Temozolomide (TMZ) remain the mainstay of treatment for glioma. While this multimodal regimen is sufficient to temporarily eliminate the bulk of the tumor mass, recurrence is inevitable and often poses major challenges for clinical management due to treatment resistance and failure to respond to targeted therapies. Improved tumor profiling capacity has enabled characterization of the genomic landscape of gliomas with the overarching goal to identify clinically relevant subtypes and inform treatment decisions. Increased tumor mutational load has been shown to correlate with higher levels of neoantigens and is indicative of the potential to induce a durable response to immunotherapy. Following treatment with TMZ, a subset of glioma has been identified to recur with increased tumor mutational load. These hypermutant recurrent glioma represent a subtype of recurrence with unique molecular vulnerabilities. In this review, we will elaborate on the current knowledge regarding the evolution of hypermutation in gliomas and the potential therapeutic opportunities that arise with TMZ-induced hypermutation in gliomas.

High-risk human papillomaviruses (HPVs) have been associated to the development of cervical and some other human cancers. Most of them express E6 and E7 oncoproteins, able to bind to p53 and retinoblastoma (pRb) tumor suppressor proteins respectively and neutralize their function. Restoration of these pathways by blocking E6 and E7 expression would provide a selective therapeutic effect. Here, we show that a clinically approved antiviral agent Cidofovir reduced E6 and E7 expression in cervical carcinoma Me180 and head and neck squamous cell carcinoma HEP2 cells at the transcriptional level. Cidofovir induced the accumulation of active p53 and pRb associated to induction of cyclin dependent kinase inhibitor p21^WAF1/CIP1 in Me180 and HEP2 cells. p53 induction was also shown in Hela HPV-positive cervical carcinoma cell line. In addition, S phase cell cycle accumulation with concomitant decrease of cyclin A expression were associated to the antiproliferative activity of Cidofovir in HPV-treated cells. Combining Cidofovir to irradiation both in vivo and in nude mice xenografts resulted in a marked radiosensitization in HPV-positive cells, which was not observed in virus negative cells. This study provides the basis for a new anticancer strategy to enhance the antitumor effect of ionizing radiation in HPV-related cancers, without increase deleterious effects.