TCTP regulates genotoxic stress and tumorigenicity via intercellular vesicular signaling.

Oncogenic intercellular signaling is regulated by extracellular vesicles (EVs), but the underlying mechanisms remain mostly unclear. Since TCTP (translationally controlled tumor protein) is an EV component, we investigated whether it has a role in genotoxic stress signaling and malignant transformation. By generating a Tctp-inducible knockout mouse model (Tctp-/f-), we report that Tctp is required for genotoxic stress-induced apoptosis signaling via small EVs (sEVs). Human breast cancer cells knocked-down for TCTP show impaired spontaneous EV secretion, thereby reducing sEV-dependent malignant growth. Since Trp53-/- mice are prone to tumor formation, we derived tumor cells from Trp53-/-;Tctp-/f- double mutant mice and describe a drastic decrease in tumori-genicity with concomitant decrease in sEV secretion and content. Remarkably, Trp53-/-;Tctp-/f- mice show highly prolonged survival. Treatment of Trp53-/- mice with sertraline, which inhibits TCTP function, increases their survival. Mechanistically, TCTP binds DDX3, recruiting RNAs, including miRNAs, to sEVs. Our findings establish TCTP as an essential protagonist in the regulation of sEV-signaling in the context of apoptosis and tumorigenicity.

SHP2 blockade enhances anti-tumor immunity via tumor cell intrinsic and extrinsic mechanisms.

SHP2 is a ubiquitous tyrosine phosphatase involved in regulating both tumor and immune cell signaling. In this study, we discovered a novel immune modulatory function of SHP2. Targeting this protein with allosteric SHP2 inhibitors promoted anti-tumor immunity, including enhancing T cell cytotoxic function and immune-mediated tumor regression. Knockout of SHP2 using CRISPR/Cas9 gene editing showed that targeting SHP2 in cancer cells contributes to this immune response. Inhibition of SHP2 activity augmented tumor intrinsic IFNγ signaling resulting in enhanced chemoattractant cytokine release and cytotoxic T cell recruitment, as well as increased expression of MHC Class I and PD-L1 on the cancer cell surface. Furthermore, SHP2 inhibition diminished the differentiation and inhibitory function of immune suppressive myeloid cells in the tumor microenvironment. SHP2 inhibition enhanced responses to anti-PD-1 blockade in syngeneic mouse models. Overall, our study reveals novel functions of SHP2 in tumor immunity and proposes that targeting SHP2 is a promising strategy for cancer immunotherapy.

TGFß-blockade uncovers stromal plasticity in tumors by revealing the existence of a subset of interferon-licensed fibroblasts.

Despite the increasing interest in targeting stromal elements of the tumor microenvironment, we still face tremendous challenges in developing adequate therapeutics to modify the tumor stromal landscape. A major obstacle to this is our poor understanding of the phenotypic and functional heterogeneity of stromal cells in tumors. Herein, we perform an unbiased interrogation of tumor mesenchymal cells, delineating the co-existence of distinct subsets of cancer-associated fibroblasts (CAFs) in the microenvironment of murine carcinomas, each endowed with unique phenotypic features and functions. Furthermore, our study shows that neutralization of TGFß in vivo leads to remodeling of CAF dynamics, greatly reducing the frequency and activity of the myofibroblast subset, while promoting the formation of a fibroblast population characterized by strong response to interferon and heightened immunomodulatory properties. These changes correlate with the development of productive anti-tumor immunity and greater efficacy of PD1 immunotherapy. Along with providing the scientific rationale for the evaluation of TGFß and PD1 co-blockade in the clinical setting, this study also supports the concept of plasticity of the stromal cell landscape in tumors, laying the foundation for future investigations aimed at defining pathways and molecules to program CAF composition for cancer therapy.

Incidental Findings in Reduction Mammoplasty Specimens in Patients with No Prior History of Breast Cancer. An Analysis of 783 Specimens.

Breast reduction surgery is a common procedure and the rate of incidental findings in the removed specimens varies between 0% and 4.6%. There are no guidelines about pathological evaluation of breast reduction surgery. We reviewed all pathology reports of patients undergoing breast reduction surgery in a single tertiary institution in Brazil from January 2008 to August 2014. Exclusion criteria were a personal history of breast cancer, unclear reason for mastectomy and incomplete data on the pathology report. We considered "relevant findings" flat epithelial atypia, atypical hyperplasia, carcinomas in situ and invasive carcinoma. Of 1672 specimens from breast reduction surgery, 783 met inclusion criteria. Median patient age was 40 (8-77), 91% underwent bilateral mastectomy and 57% of the specimens weighted less than 200 g. In 55% of cases, 4 or more paraffin blocks were sampled. There were 40 (5.1%) relevant findings and the most common was atypical lobular hyperplasia (16-2%). There were 3 invasive carcinomas (0.38%). In multivariate analysis, the only variables associated with a higher odds of relevant pathological findings were patient age ≥ 40 (OR 4.73 CI95% 1.98-11.3 p < 0.001) and sampling of ≥4 paraffin blocks from each specimen (OR 6.69 95% CI 2.25-19.9 p < 0.001). The incidence of pre-malignant and malignant lesions in specimens from breast reduction surgery is around 5%, but this risk is significantly higher for patients older than 40 years-old. Sampling at least 4 paraffin blocks from each specimen significantly increases detection rates.

Somatic mutations in early onset luminal breast cancer.

Breast cancer arising in very young patients may be biologically distinct; however, these tumors have been less well studied. We characterized a group of very young patients (≤ 35 years) for BRCA germline mutation and for somatic mutations in luminal (HER2 negative) breast cancer. Thirteen of 79 unselected very young patients were BRCA1/2 germline mutation carriers. Of the non-BRCA tumors, eight with luminal subtype (HER2 negative) were submitted for whole exome sequencing and integrated with 29 luminal samples from the COSMIC database or previous literature for analysis. We identified C to T single nucleotide variants (SNVs) as the most common base-change. A median of six candidate driver genes was mutated by SNVs in each sample and the most frequently mutated genes were PIK3CA, GATA3, TP53 and MAP2K4. Potential cancer drivers affected in the present non-BRCA tumors include GRHL2, PIK3AP1, CACNA1E, SEMA6D, SMURF2, RSBN1 and MTHFD2. Sixteen out of 37 luminal tumors (43%) harbored SNVs in DNA repair genes, such as ATR, BAP1, ERCC6, FANCD2, FANCL, MLH1, MUTYH, PALB2, POLD1, POLE, RAD9A, RAD51 and TP53, and 54% presented pathogenic mutations (frameshift or nonsense) in at least one gene involved in gene transcription. The differential biology of luminal early-age onset breast cancer needs a deeper genomic investigation.

Fibrosarcoma: a challenging diagnosis.

Fibrosarcoma represent a rare group of soft tissue malignancies derived from fibrous connective tissue and immature proliferating fibroblasts or undifferentiated anaplastic spindle cells. It affects patients in the fourth and fifth decade of life. Fibrosarcomas can be classified in subtypes such as low-grade fibromyxoid sarcoma (LGFMS) and sclerosing epithelioid fibrosarcoma (SEF), and others. Histological features that overlap between types of fibrosarcomas is well known and reported in the literature. We report the case of a 53-year-old patient who presented a tumor in the axillary fossa, which was initially diagnosed as a solitary fibrous tumor. Due to recurrence of the lesion, as well as the presence of distant metastases, the histological revision considered the diagnosis of breast metaplastic carcinoma, since the tumor expressed the p63 antigen and estrogen and progesterone receptors. Unexpected resistance to chemotherapy motivated the diagnosis re-evaluation, which was due to MUC4 expression and morphological characteristics concluded by a hybrid LGFMS-SEF tumor. The authors call attention to the difficult diagnosis in cases of soft tissue tumors. A broad panel of immunohistochemical research is required as the clinical course is essential to the final diagnosis.