Aggressive Mammary Cancers Lacking Lymphocytic Infiltration Arise in Irradiated Mice and Can Be Prevented by Dietary Intervention

Underlying anti-cancer mechanisms of histone deacetylase (HDAC) inhibitors in tamoxifen-resistant breast cancer cells

Objectives

Breast cancer is an important women's malignancy with high cancer-related deaths worldwide. Drug resistance lowers the treatment efficacy in this malignancy. This study aimed to explore the underlying mechanisms of histone deacetylase (HDAC) inhibitor trichostatin A (TSA) to overcome resistance to tamoxifen in breast cancer cells.

Materials and Methods

Tamoxifen-resistance in MCF-7 breast cancer cells was simulated. MTT assay was used to detect the cytotoxic effects of HDAC inhibitor and PI3K inhibitor on the cancer cells. Trans-well assay was applied to evaluate the invasion and migration of the treated cancer cells. Flow cytometer assay was also applied to evaluate cell cycle phases in the treated cancer cells. Finally, expression of vascular endothelial growth factor (VEGF), E-cadherin, Vimentin, phosphorylated phosphatidylinositol kinase (p-PI3k), phosphorylated protein kinase B (p-AKT), and phosphorylated mammalian target protein of rapamycin (p-mTOR) was evaluated by western blotting.

Results

The obtained results indicated that HDAC inhibitor treatments significantly decreased viability, migration, and invasion in the cancer cells. Furthermore, the frequency of the treated cancer cells significantly increased in the S phase as well as significantly decreasing in the G2/M phase of the cell cycle. Moreover, HDAC inhibitor modified levels of VEGF, E-cadherin, Vimentin, p-PI3k, p-AKT, and p-mTOR proteins. However, HDAC inhibitor combined with PI3K inhibitor exerts more profound effects on the cancer cells as compared to HDAC inhibitor monotherapy.

Conclusion

HDAC inhibitors inhibited the survival of breast cancer drug-resistant cells, invasion, migration, and angiogenesis by inhibiting the PI3k/Akt/mTOR signaling pathway.

Are charged particles a good match for combination with immunotherapy? Current knowledge and perspectives

Charged particle radiotherapy, mainly using protons and carbon ions, provides physical characteristics allowing for a volume conformal irradiation and a reduction of the integral dose to normal tissue. Carbon ion therapy additionally features an increased biological effectiveness resulting in peculiar molecular effects. Immunotherapy, mostly performed with immune checkpoint inhibitors, is nowadays considered a pillar in cancer therapy. Based on the advantageous features of charged particle radiotherapy, we review pre-clinical evidence revealing a strong potential of its combination with immunotherapy. We argue that the combination therapy deserves further investigation with the aim of translation in clinics, where a few studies have been set up already.

Regulation of dietary polyphenols on cancer cell pyroptosis and the tumor immune microenvironment

Cancer is a major public health problem that threatens human life worldwide. In recent years, immunotherapy has made great progress in both clinical and laboratory research. But the high heterogeneity and dynamics of tumors makes immunotherapy not suitable for all cancers. Dietary polyphenols have attracted researchers' attention due to their ability to induce cancer cell pyroptosis and to regulate the tumor immune microenvironment (TIME). This review expounds the regulation of dietary polyphenols and their new forms on cancer cell pyroptosis and the TIME. These dietary polyphenols include curcumin (CUR), resveratrol (RES), epigallocatechin gallate (EGCG), apigenin, triptolide (TPL), kaempferol, genistein and moscatilin. New forms of dietary polyphenols refer to their synthetic analogs and nano-delivery, liposomes. Studies in the past decade are included. The result shows that dietary polyphenols induce pyroptosis in breast cancer cells, liver cancer cells, oral squamous cells, carcinoma cells, and other cancer cells through different pathways. Moreover, dietary polyphenols exhibit great potential in the TIME regulation by modulating the programmed cell death protein 1(PD-1)/programmed death-ligand 1 (PD-L1) axis, enhancing antitumor immune cells, weakening the function and activity of immunosuppressive cells, and targeting tumor-associated macrophages (TAMs) to reduce their tumor infiltration and promote their polarization toward the M1 type. Dietary polyphenols are also used with radiotherapy and chemotherapy to improve antitumor immunity and shape a beneficial TIME. In conclusion, dietary polyphenols induce cancer cell pyroptosis and regulate the TIME, providing new ideas for safer cancer cures.

The Upregulation of Caffeic Acid Phenethyl Ester on Growth Differentiation Factor 15 Inhibits Transforming Growth Factor β/Smad Signaling in Bladder Carcinoma Cells

Growth differentiation factor 15 (GDF15) is known as a TGFβ-like cytokine acting on the TGFβ receptor to modulate target genes. GDF15 is regarded as a tumor suppressor gene in the human bladder and the caffeic acid phenethyl ester (CAPE) induces GDF15 expression to inhibit the tumor growth in vitro and in vivo. However, the interactions among GDF15, CAPE, and TGFβ/Smads signaling in the human bladder carcinoma cells remain unexplored. Results revealed that TGFβ downregulated the expression of GDF15 via the activation of Smad 2/3 and Smad 1/5. Induction of GDF15 on its downstream genes, NDRG1 and maspin, is dependent on the TGFβ/Smad pathways. Moreover, TGFβ blocked the CAPE-inducing expressions of GDF15, maspin, and NDRG1. Pretreatment of TGF receptor kinase inhibitor not only blocked the activation of TGFβ but also attenuated the activation of GDF15 on the expressions of maspin and NDRG1. The CAPE treatment attenuated the activation of TGFβ on cell proliferation and invasion. Our findings indicate that TGFβ downregulated the expressions of GDF15, maspin, and NDRG1 via TGFβ/Smad signaling. Whereas, CAPE acts as an antagonist on TGFβ/Smad signaling to block the effect of TGFβ on the GDF15 expression and cell proliferation and invasion in bladder carcinoma cells.

Race and ethnic group dependent space radiation cancer risk predictions

Future space missions by national space agencies and private industry, including space tourism, will include a diverse makeup of crewmembers with extensive variability in age, sex, and race or ethnic groups. The relative risk (RR) model is used to transfer epidemiology data between populations to estimate radiation risks. In the RR model cancer risk is assumed to be proportional to background cancer rates and limited by other causes of death, which are dependent on genetic, environmental and dietary factors that are population dependent. Here we apply the NSCR-2020 model to make the first predictions of age dependent space radiation cancer risks for several U.S. populations, which includes Asian-Pacific Islanders (API), Black, Hispanic (white and black), and White (non-Hispanic) populations. Results suggest that male API and Hispanic populations have the overall lowest cancer risks, while White females have the highest risk. Blacks have similar total cancer rates than Whites, however their reduced life expectancy leads to modestly lower lifetime radiation risks compared to Whites. There are diverse tissue specific cancer risk ranking across sex and race, which include sex specific organ risks, female’s having larger lung, stomach, and urinary-bladder radiation risks, and male’s having larger colon and brain risks.

Mammary tumor-derived transplants as breast cancer models to evaluate tumor-immune interactions and therapeutic responses

In breast cancer, the type and distribution of infiltrating immune cells are associated with clinical outcome. Moreover, infiltrated cancers with abundant tumor infiltrating lymphocytes (TIL) are more likely to respond to immunotherapy, while those in which CD8+ T cells are completely absent (deserts) or excluded are less likely to respond. Detailed understanding of this biology is limited by a lack of preclinical breast cancer models that recapitulate TIL distributions and their associated biology. Here we established mammary tumor-derived transplants (mTDT) from 12 Trp53 null mammary tumors in syngeneic BALB/cJ mice and examined the stability of their growth rate, TIL distribution, and transcriptomic profiles. All mTDT were estrogen receptor negative. Half of the parental tumors were classified as infiltrated, and the rest were divided between excluded and desert phenotypes. After two orthotopic passages, most (70%) mTDT from infiltrated parents recapitulated this pattern, whereas the desert or excluded parental patterns were maintained in about half of daughter mTDT. Approximately 30% of mTDT gave rise to lung or liver metastases, but metastasis was not associated with a TIL phenotype. Unsupervised transcriptomic analysis clustered mTDT according to their TIL spatial patterns. Infiltrated mTDT transplanted subcutaneously and orthotopically were resistant to anti-PD-L1. Profiling implicated prolonged antigen stimulation and loss of effector function of lymphocytes rather than T cell exhaustion in the lack of response of infiltrated mTDT to checkpoint blockade. In summary, the molecular diversity and immune complexity of mTDT will facilitate the dissection of mechanisms of breast cancer response to immunotherapies.

A proposed change to astronaut exposures limits is a giant leap backwards for radiation protection

Addressing the uncertainties in assessing health risks from cosmic ray heavy ions is a major scientific challenge recognized by many previous reports by the National Academy of Sciences (NAS) and the National Council on Radiation Protection and Measurements (NCRP) advising the National Aeronautics and Space Administration (NASA). These reports suggested a series of steps to pursue the scientific basis for space radiation protection, including the implementation of age and sex dependent risk assessments and exposure limits appropriate for a small population of radiation workers, the evaluation of uncertainties in risk projections, and developing a vigorous research program in heavy ion radiobiology to reduce uncertainties and discover effective countermeasures. The assessment of uncertainties in assessing risk provides protection against changing assessments of risk, reveals limitations in information used in space mission operations, and provides the impetus to reduce uncertainties and discover the true level of risk and possible effectiveness of countermeasures through research. However, recommendations of a recent NAS report, in an effort to minimize differences in age and sex on flight opportunities, suggest a 600 mSv career effective dose limit based on a median estimate to reach 3% cancer fatality for 35-year old females. The NAS report does not call out examples where females would be excluded from space missions planned in the current decade using the current radiation limits at NASA. In addition, there are minimal considerations of the level of risk to be encountered at this exposure level with respect to the uncertainties of heavy ion radiobiology, and risks of cancer, as well as cognitive detriments and circulatory diseases. Furthermore, their recommendation to limit Sieverts and not risk in conjunction with a waiver process is essentially a recommendation to remove radiation limits for astronauts. We discuss issues with several of the NAS recommendations with the conclusion that the recommendations could have negative impacts on crew health and safety, and violate the three principles of radiation protection (to prevent clinically significant deterministic effects, limit stochastic effects, and practice ALARA), which would be a giant leap backwards for radiation protection.

Inflammation Mediates the Development of Aggressive Breast Cancer Following Radiotherapy

PURPOSE

Women treated with radiotherapy before 30 years of age have increased risk of developing breast cancer at an early age. Here, we sought to investigate mechanisms by which radiation promotes aggressive cancer.

EXPERIMENTAL DESIGN

The tumor microenvironment (TME) of breast cancers arising in women treated with radiotherapy for Hodgkin lymphoma was compared with that of sporadic breast cancers. To investigate radiation effects on carcinogenesis, we analyzed tumors arising from Trp53-null mammary transplants after irradiation of the target epithelium or host using immunocompetent and incompetent mice, some of which were treated with aspirin.

RESULTS

Compared with age-matched specimens of sporadic breast cancer, radiation-preceded breast cancers (RP-BC) were characterized by TME rich in TGFβ, cyclooxygenase 2, and myeloid cells, indicative of greater immunosuppression, even when matched for triple-negative status. The mechanism by which radiation impacts TME construction was investigated in carcinomas arising in mice bearing Trp53-null mammary transplants. Immunosuppressive TMEs (iTME) were recapitulated in mice irradiated before transplantation, which implicated systemic immune effects. In nu/nu mice lacking adaptive immunity irradiated before Trp53-null mammary transplantation, cancers also established an iTME, which pointed to a critical role for myeloid cells. Consistent with this, irradiated mammary glands contained more macrophages and human cells cocultured with polarized macrophages underwent dysplastic morphogenesis mediated by IFNγ. Treating mice with low-dose aspirin for 6 months postirradiation prevented establishment of an iTME and resulted in less aggressive tumors.

CONCLUSIONS

These data show that radiation acts via nonmutational mechanisms to promote markedly immunosuppressive features of aggressive, RP-BCs.

Targeting the tumor immune microenvironment with "nutraceuticals": From bench to clinical trials

The occurrence of immune effector cells in the tissue microenvironment during neoplastic progression is critical in determining tumor growth outcomes. On the other hand, tumors may also avoid immune system-mediated elimination by recruiting immunosuppressive leukocytes and soluble factors, which coordinate a tumor microenvironment that counteracts the efficiency of the antitumor immune response. Checkpoint inhibitor therapy results have indicated a way forward via activation of the immune system against cancer. Widespread evidence has shown that different compounds in foods, when administered as purified substances, can act as immunomodulators in humans and animals. Although there is no universally accepted definition of nutraceuticals, the term identifies a wide category of natural compounds that may impact health and disease statuses and includes purified substances from natural sources, plant extracts, dietary supplements, vitamins, phytonutrients, and various products with combinations of functional ingredients. In this review, we summarize the current knowledge on the immunomodulatory effects of nutraceuticals with a special focus on the cancer microenvironment, highlighting the conceptual benefits or drawbacks and subtle cell-specific effects of nutraceuticals for envisioning future therapies employing nutraceuticals as chemoadjuvants.