Heterogeneity and immunophenotypic plasticity of malignant cells in human liposarcomas

Phosphorylation of IWS1 by AKT maintains liposarcoma tumor heterogeneity through preservation of cancer stem cell phenotypes and mesenchymal-epithelial plasticity

Chemotherapy remains the mainstay of treatment for patients with advanced liposarcoma (LPS), but response rates are only 25% and the overall survival at 5 years is dismal at 20-34%. Translation of other therapies have not been successful and there has been no significant improvement in prognosis for nearly 20 years. The aberrant activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway has been implicated in the aggressive clinical behavior LPS and in resistance to chemotherapy, but the precise mechanism remains elusive and efforts to target AKT clinically have failed. Here we show that the AKT-mediated phosphorylation of the transcription elongation factor IWS1, promotes the maintenance of cancer stem cells in both cell and xenograft models of LPS. In addition, phosphorylation of IWS1 by AKT contributes to a "metastable" cell phenotype, characterized by mesenchymal/epithelial plasticity. The expression of phosphorylated IWS1 also promotes anchorage-dependent and independent growth, cell migration, invasion, and tumor metastasis. In patients with LPS, IWS1 expression is associated with reduced overall survival, increased frequency of recurrence, and shorter time to relapse after resection. These findings indicate that IWS1-mediated transcription elongation is an important regulator of human LPS pathobiology in an AKT-dependent manner and implicate IWS1 as an important molecular target to treat LPS.

Fatty acid mobilization from adipose tissue is mediated by CD36 post-translational modifications and intracellular trafficking

The mechanism controlling long-chain fatty acid (LCFA) mobilization from adipose tissue is not well understood. Here, we investigated how the LCFA transporter CD36 regulates this process. By using tissue-specific KO mouse models, we showed that CD36 in adipocytes and endothelial cells mediated both LCFA deposition into and release from adipose tissue. We demonstrated the role of adipocytic and endothelial CD36 in promoting tumor growth and chemoresistance conferred by adipose tissue–derived LCFAs. We showed that dynamic cysteine S-acylation of CD36 in adipocytes, endothelial cells, and cancer cells mediated intercellular LCFA transport. We demonstrated that lipolysis induction in adipocytes triggered CD36 deacylation and deglycosylation, as well as its dissociation from interacting proteins, prohibitin-1 (PHB) and annexin 2 (ANX2). Our data indicate that lipolysis triggers caveolar endocytosis and translocation of CD36 from the cell membrane to lipid droplets. This study suggests a mechanism for both outside-in and inside-out cellular LCFA transport regulated by CD36 S-acylation and its interactions with PHB and ANX2.

Hypoxic niches are endowed with a protumorigenic mechanism that supersedes the protective function of PTEN

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide and is characterized by a fast-paced growth. Like other solid tumors, the HNSCC growth rate results in the development of hypoxic regions identified by the expression of hypoxia-inducible factor 1α (HIF-1α). Interestingly, clinical data have shown that pharmacological induction of intratumoral hypoxia caused an unexpected rise in tumor metastasis and the accumulation of cancer stem cells (CSCs). However, little is known on the molecular circuitries involved in the presence of intratumoral hypoxia and the augmented population of CSCs. Here we explore the impact of hypoxia on the behavior of HNSCC and define that the controlling function of phosphatase and tensin homolog (PTEN) over HIF-1α expression and CSC accumulation are de-regulated during hypoxic events. Our findings indicate that hypoxic niches are poised to accumulate CSCs in a molecular process driven by the loss of PTEN activity. Furthermore, our data suggest that targeted therapies aiming at the PTEN/PI3K signaling may constitute an effective strategy to counteract the development of intratumoral hypoxia and the accumulation of CSCs.-Nascimento-Filho, C. H. V., Webber, L. P., Borgato, G. B., Goloni-Bertollo, E. M., Squarize, C. H., Castilho, R. M. Hypoxic niches are endowed with a protumorigenic mechanism that supersedes the protective function of PTEN.

Scavenger Receptor Class B Type 1 (SR-B1) being a Potential Biomarker for the Diagnosis of Liposarcoma and Associated with the Degree of Differentiation of Liposarcomas

Background: Soft tissue sarcomas include multiple histological subtypes and are highly aggressive. Moreover, SR-B1 is associated with malignant behavior and poor prognosis in a variety of cancers. However, there have been no attempts to assess whether SR-B1 expression in soft tissue sarcoma. We aimed to detect the expression levels of the SR-B1 protein in soft tissue sarcoma.

Methods: We assessed SR-B1 expression via immunohistochemistry and tissue microarrays in 107 soft tissue sarcomas with 4 phenotypes: 26 liposarcomas, 18 Ewing's sarcomas, 20 rhabdomyosarcomas and 43 leiomyosarcomas.

Results: Tumor cell SR-B1 expression was seen in 18/26 (69.2%) liposarcomas, 1/18 (5.55%) Ewing's sarcomas, 1/20 (5.00%) rhabdomyosarcomas, 2/43 (4.70%) leiomyosarcomas and was stained in the cell membrane. We found that SR-B1 expression in liposarcomas (18/26) was significantly higher than that in non-lipomatous sarcomas (4/77) (χ2 = 49.811, p = 0.000) and in well-differentiated liposarcoma (13/15) was significantly higher than that in dedifferentiated liposarcoma (5/11) (p = 0.038). No significant correlation was found between SR-B1 and gender, nationality, size and tumor location (p > 0.05), but it was significantly associated with ages (χ2 = 11.426, p = 0.001) and sarcoma phenotypes (χ2 = 49.817, p = 0.000).

Conclusion: Our findings highlight the highly expression of SR-B1 in liposarcomas. SR-B1 may be a potential biomarker for the diagnosis of liposarcoma and may indicate the degree of differentiation of liposarcomas.

Autologous fat grafting after sarcoma surgery: Evaluation of oncological safety

BACKGROUND

The regenerative effectiveness of lipoaspirate procedures relies on the presence of mesenchymal stem cells, but the stromal microenvironment and hormonal secretions of the adipose tissue may be involved in cancer growth. Only few oncological outcome studies of fat grafting at the surgical site of malignant neoplasms of mesenchymal origin are available; none of these studies examined a series of sarcoma cases.

OBJECTIVES

We analyzed outcome in terms of local or distant spread and overall survival to investigate the oncological safety of fat grafting in patients with sarcoma.

PATIENTS AND METHODS

Sixty consecutive patients who had undergone 143 fat grafting procedures after surgical resection of bone and soft tissue sarcomas of the head, trunk, and limbs with clear resection margins were enrolled from 2004 to 2015 in our tertiary care center. A multidisciplinary sarcoma team administered adjuvant therapies. Patients were recurrence free at fat grafting.

RESULTS

The overall median follow-up was 7.5 years. At follow-up after fat grafting (2.4 years), one patient had distant metastasis and two had local relapse. Kaplan-Meier analysis showed disease-free survival rate of 95.4% (CI: 89.1-100.0) at 24 months. The risk of local recurrence (LR) within 24 months was 4.6% (CI: 0.0-20.9). The probability of not having LR after fat grafting was ≥ 89.1%.

CONCLUSION

We found no evidence of an increased cancer risk after fat grafting procedures in patients with sarcoma, but a stimulatory role of fat cannot be excluded for bone sarcomas based on the cases reported here, and further studies are therefore needed.

Sex Differences and Bone Metastases of Breast, Lung, and Prostate Cancers: Do Bone Homing Cancers Favor Feminized Bone Marrow?

Sex-associated differences in bone metastasis formation from breast, lung, and prostate cancer exist in clinical studies, but have not been systematically reviewed. Differences in the bone marrow niche can be attributed to sexual dimorphism, to genetic variations that affect sex hormone levels, or to the direct effects of sex hormones, natural or exogenously delivered. This review describes the present understanding of sex-associated and sex hormone level differences in the marrow niche and in formation of bone metastasis during the transition of these three cancers from treatable disease to an often untreatable, lethal metastatic one. Our purpose is to provide insight into some underlying molecular mechanisms for hormonal influence in bone metastasis formation, and to the potential influence of sexual dimorphism, genetic differences affecting sex assignment, and sex hormone level differences on the bone niche and its favorability for metastasis formation. We reviewed publications in PubMed and EMBASE, including full length manuscripts, case reports, and clinical studies of relevance to our topic. We focused on bone metastasis formation in breast, lung, and prostate cancer because all three commonly present with bone metastases. Several clear observations emerged. For breast cancer bone metastasis formation, estrogen receptor (ER) signaling pathways indicate a role for ER beta (ERβ). Estrogen influences the bone microenvironment, creating and conditioning a favorable niche for colonization and breast cancer progression. For lung cancer, studies support the hypothesis that females have a more favorable bone microenvironment for metastasis formation. For prostate cancer, a decrease in the relative androgen to estrogen balance or a “feminization” of bone marrow favors bone metastasis formation, with a potentially important role for ERβ that may be similar to that in breast cancer. Long-term estrogen administration or androgen blockade in males may feminize the bone marrow niche to one more favorable for bone metastases in prostate cancer. Administration of androgens in females, especially combined with mastectomy, may reduce risk of developing bone metastatic breast cancer. We conclude that it should be considered that females, those with female-leaning genetic variations, or hormonal states that feminize the bone marrow, may offer favorable sites for bone metastases.

Cytokine signaling regulating adipose stromal cell trafficking

Adipocyte progenitors, known as adipose stromal cells (ASC), can become mobilized, recruited by tumors, and contribute to cancer progression. Mechanisms underlying ASC trafficking have remained obscure. We recently reported that CXCL1 expressed by cancer cells chemoattracts ASC expressing CXCR1 in obesity. As a candidate mechanism of CXCL1 activation, we identified interleukin (IL)-22, systemic circulation of which is increased in obesity. It has been reported that IL-22 signaling through IL-22R is upstream of CXCL1. Here, we provide evidence that IL-22 expression by leukocytes infiltrating WAT and IL-22R expression by tumors is obesity-dependent. We propose that obesity-associated adipocyte death and the resulting recruitment of leukocytes triggers the IL-22 signaling cascade that induces CXCL1 secretion by cancer cells responsible for ASC trafficking to tumors.

Hypothesis: The Intratumoral Immune Response against a Cancer Progenitor Cell Impacts the Development of Well-Differentiated versus Dedifferentiated Disease in Liposarcoma

Well-differentiated/dedifferentiated (WD/DD) liposarcoma is a rare malignancy of adipocyte origin (“fat cancer”). Tumors may be entirely WD, WD with a DD component, or rarely DD without a clear WD component. WD tumors are low grade and generally indolent, while tumors with a DD component are high grade and behave much more aggressively, with a modest potential for distant metastasis. The presence of cancer progenitor cells in WD/DD liposarcoma is suggested by clinical evidence and reported research findings. In addition, there are emerging data to support the existence of a naturally occurring, antigen-driven, and adaptive immune response within the tumor microenvironment. We hypothesize that the intratumoral immune response is directed against a cancer progenitor cell and that the outcome of this response impacts the development of WD versus DD disease. Further study will likely provide interesting insights into the disease biology of WD/DD liposarcoma that may be readily translated to other more common cancers.

Obesity, proinflammatory mediators, adipose tissue progenitors, and breast cancer

PURPOSE OF REVIEW

There is emerging evidence that obesity is associated with an increase in the incidence, severity, and mortality from different types of cancer, including postmenopausal breast cancer. Here, we discuss the role of white adipose tissue (WAT) cells and of related soluble factors in the local and metastatic growth of this neoplastic disease. Moreover, we discuss the recent increase in the use of WAT-derived progenitor cells in breast cancer patients to enhance the quality of breast reconstruction and the related risks.

RECENT FINDINGS

In several murine models, WAT cells and progenitors were found to have cooperative roles in promoting local breast cancer. Moreover, they were found to contribute to adipocytes and pericytes supporting the cancer vasculature, and stimulated the metastatic progression of breast cancer. There are some clinically retrospective data showing a significant increase in the frequency of intraepithelial neoplasia in patients who received a lipofilling procedure for breast reconstruction compared with controls.

SUMMARY

Preclinical models and clinical studies are urgently needed to investigate how to inhibit the tumor-promoting activity of WAT cells and progenitors. The risks associated with the use of WAT cells for breast reconstructions should be better investigated retrospectively and prospectively.

Stem cells from adipose tissue and breast cancer: hype, risks and hope

Several recent papers have generated new hope about the use of white adipose tissue (WAT)-derived progenitor cells for soft tissue reconstruction in a variety of diseases including breast cancer (BC), a procedure that is increasingly used worldwide. We revised the available literature about WAT cells and BC. In the BC field, we believe that the hype for the exciting results in terms of WAT progenitor cell engraftment and tissue augmentation should be tempered when considering the recent and abundant preclinical studies, indicating that WAT progenitors may promote BC growth and metastasis. White adipose tissue progenitors can contribute to tumour vessels, pericytes and adipocytes, and were found to stimulate local and metastatic BC progression in several murine models. Moreover, there are clinical retrospective data showing a significant increase in the local recurrence frequency in patients with intraepithelial neoplasia who received a lipofilling procedure for breast reconstruction compared with controls. Retrospective and prospective clinical trials are warranted to investigate in depth the safety of this procedure in BC. Preclinical models should be used to find mechanisms able to inhibit the tumour-promoting activity of WAT progenitors while sparing their tissue reconstruction potential.

Characterization of cancer stem-like cells derived from mouse induced pluripotent stem cells transformed by tumor-derived extracellular vesicles

Several studies have shown that cancer niche can perform an active role in the regulation of tumor cell maintenance and progression through extracellular vesicles-based intercellular communication. However, it has not been reported whether this vesicle-mediated communication affects the malignant transformation of normal stem cells/progenitors. We have previously reported that the conditioned medium derived from the mouse Lewis Lung Carcinoma (LLC) cell line can convert mouse induced pluripotent stem cells (miPSCs) into cancer stem cells (CSCs), indicating that normal stem cells when placed in an aberrant microenvironment can give rise to functionally active CSCs. Here, we focused on the contribution of tumor-derived extracellular vesicles (tEVs) that are secreted from LLC cells to induce the transformation of miPSCs into CSCs. We isolated tEVs from the conditioned medium of LLC cells, and then the differentiating miPSCs were exposed to tEVs for 4 weeks. The resultant tEV treated cells (miPS-LLCev) expressed Nanog and Oct3/4 proteins comparable to miPSCs. The frequency of sphere formation of the miPS-LLCev cells in suspension culture indicated that the self-renewal capacity of the miPS-LLCev cells was significant. When the miPS-LLCev cells were subcutaneously transplanted into Balb/c nude mice, malignant liposarcomas with extensive angiogenesis developed. miPS-LLCevPT and miPS-LLCevDT, the cells established from primary site and disseminated liposarcomas, respectively, showed their capacities to self-renew and differentiate into adipocytes and endothelial cells. Moreover, we confirmed the secondary liposarcoma development when these cells were transplanted. Taken together, these results indicate that miPS-LLCev cells possess CSC properties. Thus, our current study provides the first evidence that tEVs have the potential to induce CSC properties in normal tissue stem cells/progenitors.

Apoptotic death of cancer stem cells for cancer therapy

Cancer stem cells (CSCs) play crucial roles in tumor progression, chemo- and radiotherapy resistance, and recurrence. Recent studies on CSCs have advanced understanding of molecular oncology and development of novel therapeutic strategies. This review article updates the hypothesis and paradigm of CSCs with a focus on major signaling pathways and effectors that regulate CSC apoptosis. Selective CSC apoptotic inducers are introduced and their therapeutic potentials are discussed. These include synthetic and natural compounds, antibodies and recombinant proteins, and oligonucleotides.