Physiological and environmental factors affecting cancer risk and prognosis in obesity.

Obesity results from a chronic excessive accumulation of adipose tissue due to a long-term imbalance between energy intake and expenditure. Available epidemiological and clinical data strongly support the links between obesity and certain cancers. Emerging clinical and experimental findings have improved our understanding of the roles of key players in obesity-associated carcinogenesis such as age, sex (menopause), genetic and epigenetic factors, gut microbiota and metabolic factors, body shape trajectory over life, dietary habits, and general lifestyle. It is now widely accepted that the cancer-obesity relationship depends on the site of cancer, the systemic inflammatory status, and micro environmental parameters such as levels of inflammation and oxidative stress in transforming tissues. We hereby review recent advances in our understanding of cancer risk and prognosis in obesity with respect to these players. We highlight how the lack of their consideration contributed to the controversy over the link between obesity and cancer in early epidemiological studies. Finally, the lessons and challenges of interventions for weight loss and better cancer prognosis, and the mechanisms of weight gain in survivors are also discussed.

Insulin-like growth factor-1 signaling in the tumor microenvironment: Carcinogenesis, cancer drug resistance, and therapeutic potential.

The tumor microenvironment fuels tumorigenesis and induces the development of resistance to anticancer drugs. A growing number of reports support that the tumor microenvironment mediates these deleterious effects partly by overexpressing insulin-like growth factor 1 (IGF-1). IGF-1 is known for its role to support cancer progression and metastasis through the promotion of neovascularization in transforming tissues, and the promotion of the proliferation, maintenance and migration of malignant cells. Anti-IGF therapies showed potent anticancer effects and the ability to suppress cancer resistance to various chemotherapy drugs in in vivo and in vitro preclinical studies. However, high toxicity and resistance to these agents are increasingly being reported in clinical trials. We review data supporting the notion that tumor microenvironment mediates tumorigenesis partly through IGF-1 signaling pathway. We also discuss the therapeutic potential of IGF-1 receptor targeting, with special emphasis on the ability of IGF-R silencing to overcome chemotherapy drug resistance, as well as the challenges for clinical use of anti-IGF-1R therapies.

Euphol from Tapinanthus sp. Induces Apoptosis and Affects Signaling Proteins in Glioblastoma and Prostate Cancer Cells

BACKGROUND: Plants play an important role in cancer therapy. They are source of natural molecules which can induce apoptosis in cancer cells by affecting molecular mechanisms implicated in cancer progression. The MAP Kinase/ERK1/2 and PI3K/AKT signaling pathways are two classical signaling pathways implicated in cancer progression and constitute therapeutic targets against cancer. This study aimed to evaluate the effect of euphol on MAP Kinase/ERK1/2 and PI3K/AKT signaling pathways in glioblastoma and prostate cancer cells. Euphol is a tetracyclique triterpene alcohol isolated from Tapinanthus sp. which is a hemi parasitic plant belonging to Loranthaceae family. METHODS: Plant powder was extracted by maceration and euphol was isolated and described using respectively column chromatography separation on silica gel and spectroscopic data. Cytotoxic effect of euphol was evaluated using XTT assay and its effect on MAP Kinase/ERK1/2 and PI3K/AKT protein expression was investigated by Western immunoblot analysis. Apotosis was analyzed by evaluating caspase-3/7 activity. RESULTS: Our investigations demonstrated that this compound has an important cytotoxic effect on C6 and U87 MG glioblastoma (GBM) cells and PC-3 prostate cancer cells. Furthermore, euphol-induced apoptosis revealed by elevated caspase 3/7 activity, was correlated with a significant inhibition of MAP kinase/Erk 1/2 and PI3K/Akt signaling pathway in glioblastoma U87 MG cells. The reverse effect was observed in C6 glioblastoma cells, where apoptosis was correlated with a long-lasting activation of Erk 1/2.  In PC-3 cells, euphol had no or limited effect on Erk 1/2 and Akt activity. CONCLUSION: These results indicate that euphol induces cell death in glioblastoma and prostate cancer cells and regulates significantly Erk1/2 and Akt activity in glioblastoma cells.

Prevalence of precancerous cervical lesions and high-risk human papillomavirus types in Yaounde, Cameroon.

INTRODUCTION: Various Human papillomavirus (HPV) types cause cervical cancer, and represent the primary cause of cancer death in Africa and the second cause of most common cancers in Cameroon. Herein, we determined the prevalence of high-risk HPV types in women and associated cervical cytologic abnormalities in Yaounde, Cameroon. METHODOLOGY: A cross-sectional study targeting HPV-positive women aged 20 and over was conducted between March and June 2020 at the Saint Martin de Porres' Health Centre in Yaounde. HPV tests were performed by PCR for detection of HPVs 16, 18, 33, and 45. The test was performed on 616 women using exfoliated cell specimens; then, we processed on cytological diagnosis with Pap smears on HPV positive specimens. RESULTS: The HPV types tested were detected in 137 participants, of which 38.7% with multiple HPV infections, and the remaining part with single HPV infections of type HPV 16 (28.5%), HPV 18 (17.5%), HPV 33 (10.2%), and HPV 45 (5.1%). Cervical cytologic abnormalities were found in 69.34% of participants including: LSIL (49.63%), HSIL (15.32%), ASC-US (3.66%) and AGC (0.73%). Co-infections with HPV 16 and HPV 18 were significantly associated with HSIL (p = 0.001) lesions, while HPV 45 was more common in participants with normal cytology (p = 0.001). Cervical lesion occurrence was significantly associated with the number of sexual partners (p = 0.02) and history of oral contraceptive pill use (p = 0.001). CONCLUSIONS: Our results suggest that HPV 16 and 18 are predominant in Yaounde, and are associated with more severe precancerous lesions.

Influence of HIV infection on the distribution of high-risk HPV types among women with cervical precancerous lesions in Yaounde, Cameroon.

OBJECTIVES: To characterize high-risk HPV types associated with cervical precancerous lesions in women living in Yaounde, Cameroon, and to determine their distribution with HIV status. METHODS: Women with abnormal pap smears recorded from February 2015 to May 2019 at Saint Martin de Porres' Health Centre, Yaounde, Cameroon, were recruited in this study after obtaining informed consent. Pap smears were collected and re-examined. Human immunodeficiency virus (HIV) serology was determined. HPV16, 18, 33, and 45 were assessed using standard PCR. RESULTS: All included participants (370) were HPV-positive and had either low grade squamous intraepithelial lesions (67.03%) or high grade squamous intraepithelial lesions (31.35%). They were subdivided into HIV-positive (N =102) and HIV-negative (N =268). In the HIV-negative subgroup, we observed 66.04% HPV16-positve, 41.79% HPV18-positve, 21.27% HPV33-positve and 8.21% HPV45-positve. In the HIV-positive subgroup, we observed 22.55% HPV16-positve, 5.88% HPV18-positve, 75.49% HPV33-positve, and 49.02% HPV45-positve. Married HIV-positive participants (47.14 ± 1.19) were older than both their single counterparts (34.94±1.22, P = 0.0008) and HIV-negative participants (41.43 ± 0.79, P = 0.0001). Single HIV-positive women reported higher numbers of miscarriages (P = 0.0023), and had later first sexual intercourse than HIV-negative (P = 0.0079) women. CONCLUSION: Our study suggested differential expressions in high-risk HPV types with HIV status and cervical precancerous lesions and warrants more extensive studies.

Anticancer Activity of Combretum fragrans F. Hoffm on Glioblastoma and Prostate Cancer Cell Lines.

BACKGROUND: Cancer incidence has been growing in an alarming rate worldwide and new therapeutics are needed, particularly for intractable and chemoresistant cases. We evaluated the cytotoxic effects of Combretum fragrans F. Hoffm (Combretaceae) on glioblastoma (U87MG and C6) and prostate (PC-3) cancer cell lines. METHODS: The cytotoxic effect of the methanolic extract of the stem bark of Combretum fragrans was assessed using XTT (2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide) test. Expressions of Akt and ERK1/2 were determined using Western blot technique, while Caspase-3/7 kits were used to evaluate caspase-3/7 activity. RESULTS: C. fragrans extract inhibited the proliferation of U87 (IC50 = 20.13 µg/mL), C6 (IC50 = 12.17 µg/mL), and PC-3 (IC50 = 11.50 µg/mL) cells. Treatment with the extract resulted in lower levels (p < 0.001) of phospho-ERK1/2 and phospho-Akt in U87 cells, and instead, higher levels of phospho-ERK1/2 (p < 0.001) in C6 and PC-3 cells. An increase in caspase-3/7 activity was observed, mainly after 24 hours of treatment, indicating the activation of apoptotic processes. CONCLUSION: Altogether, these results suggest that C. fragrans have potent anticancer properties. This plant should be further investigated for developing new anticancer drugs.

Tumor Microenvironment Uses a Reversible Reprogramming of Mesenchymal Stromal Cells to Mediate Pro-tumorigenic Effects.

The role of mesenchymal stromal cells (MSCs) in the tumor microenvironment is well described. Available data support that MSCs display anticancer activities, and that their reprogramming by cancer cells in the tumor microenvironment induces their switch toward pro-tumorigenic activities. Here we discuss the recent evidence of pro-tumorigenic effects of stromal cells, in particular (i) MSC support to cancer cells through the metabolic reprogramming necessary to maintain their malignant behavior and stemness, and (ii) MSC role in cancer cell immunosenescence and in the establishment and maintenance of immunosuppression in the tumor microenvironment. We also discuss the mechanisms of tumor microenvironment mediated reprogramming of MSCs, including the effects of hypoxia, tumor stiffness, cancer-promoting cells, and tumor extracellular matrix. Finally, we summarize the emerging strategies for reprogramming tumor MSCs to reactivate anticancer functions of these stromal cells.

Emerging data supporting stromal cell therapeutic potential in cancer: reprogramming stromal cells of the tumor microenvironment for anti-cancer effects.

After more than a decade of controversy on the role of stromal cells in the tumor microenvironment, the emerging data shed light on pro-tumorigenic and potential anti-cancer factors, as well as on the roots of the discrepancies. We discuss the pro-tumorigenic effects of stromal cells, considering the effects of tumor drivers like hypoxia and tumor stiffness on these cells, as well as stromal cell-mediated adiposity and immunosuppression in the tumor microenvironment, and cancer initiating cells' cellular senescence and adaptive metabolism. We summarize the emerging data supporting stromal cell therapeutic potential in cancer, discuss the possibility to reprogram stromal cells of the tumor microenvironment for anti-cancer effects, and explore some causes of discrepancies on the roles of stromal cells in cancer in the available literature.