Tumour microenvironment and metabolic plasticity in cancer and cancer stem cells: Perspectives on metabolic and immune regulatory signatures in chemoresistant ovarian cancer stem cells.

Cancer stem cells (CSCs) are a sub-population of tumour cells, which are responsible to drive tumour growth, metastasis and therapy resistance. It has recently been proposed that enhanced glucose metabolism and immune evasion by tumour cells are linked, and are modulated by the changing tumour microenvironment (TME) that creates a competition for nutrient consumption between tumour and different sub-types of cells attracted to the TME. To facilitate efficient nutrient distribution, oncogene-induced inflammatory milieu in the tumours facilitate adaptive metabolic changes in the surrounding non-malignant cells to secrete metabolites that are used as alternative nutrient sources by the tumours to sustain its increasing energy needs for growth and anabolic functions. This scenario also affects CSCs residing at the primary or metastatic niches. This review summarises recent advances in our understanding of the metabolic phenotypes of cancer cells and CSCs and how these processes are affected by the TME. We also discuss how the evolving TME modulates tumour cells and CSCs in cancer progression. Using previously described proteomic and genomic platforms, ovarian cancer cell lines and a mouse xenograft model we highlight the existence of metabolic and immune regulatory signatures in chemoresistant ovarian CSCs, and discuss how these processes may affect recurrence in ovarian tumours. We propose that progress in cancer control and eradication may depend not only on the elimination of highly chemoresistant CSCs, but also in designing novel strategies which would intervene with the tumour-promoting TME factors.

Ahmed N ，Escalona R ，Leung D ，Chan E ，Kannourakis G ... -  《-》

Tumour Cell Secretome in Chemoresistance and Tumour Recurrence.

Chemoresistance is a major factor driving tumour relapse and the high rates of cancer-related deaths. Understanding how cancer cells overcome chemotherapy-induced cell death is critical in promoting patient survival. One emerging mechanism of chemoresistance is the tumour cell secretome (TCS), an array of protumorigenic factors released by tumour cells. Chemotherapy exposure can also alter the composition of the TCS, known as therapy-induced TCS, and can promote tumour relapse and the formation of an immunosuppressive tumour microenvironment (TME). Here, we outline how the TCS can protect cancer cells from chemotherapy-induced cell death. We also highlight recent evidence describing how therapy-induced TCS can impact cancer stem cell (CSC) expansion and tumour-associated immune cells to enable tumour regrowth and antitumour immunity.

Madden EC ，Gorman AM ，Logue SE ，Samali A ... -  《Trends in Cancer》

Cancer Stem Cell markers: Symphonic masters of chemoresistance and immune evasion.

Cancer Stem Cells (CSCs) are highly tumorigenic, chemoresistant, and immune evasive. They emerge as a central driver that gives rise to the bulk of tumoral mass, modifies the tumor microenvironment (TME), and exploits it, leading to poor clinical outcomes for patients with cancer. The existence of CSCs thus accounts for the failure of conventional therapies and immune surveillance. Identifying CSCs in solid tumors remains a significant challenge in modern oncology, with the use of cell surface markers being the primary strategy for studying, isolating, and enriching these cells. In this review, we explore CSC markers, focusing on the underlying signaling pathways that drive CSC self-renewal, which simultaneously makes them intrinsically chemoresistant and immune system evaders. We comprehensively discuss the autonomous and non-autonomous functions of CSCs, with particular emphasis on their interactions with the tumor microenvironment, especially immune cells. This reciprocal network enhances CSCs malignancy while compromising the surrounding niche, ultimately defining therapeutic vulnerabilities associated with each CSC marker. The most common CSCs surface markers addressed in this review-CD44, CD133, ICAM1/CD54, and LGR5-provide insights into the interplay between chemoresistance and immune evasion, two critically important phenomena in disease eradication. This new perspective on the state-of-the-art of CSCs will undoubtedly open new avenues for therapy.

Sarabia-Sánchez MA ，Tinajero-Rodríguez JM ，Ortiz-Sánchez E ，Alvarado-Ortiz E ... -  《-》

Chemotherapy Enriches for Proinflammatory Macrophage Phenotypes that Support Cancer Stem-Like Cells and Disease Progression in Ovarian Cancer.

High-grade serous ovarian cancer remains a poorly understood disease with a high mortality rate. Although most patients respond to cytotoxic therapies, a majority will experience recurrence. This may be due to a minority of drug-resistant cancer stem-like cells (CSC) that survive chemotherapy and are capable of repopulating heterogeneous tumors. It remains unclear how CSCs are supported in the tumor microenvironment (TME) particularly during chemotherapy exposure. Tumor-associated macrophages (TAM) make up half of the immune population of the ovarian TME and are known to support CSCs and contribute to cancer progression. TAMs are plastic cells that alter their phenotype in response to environmental stimuli and thus may influence CSC maintenance during chemotherapy. Given the plasticity of TAMs, we studied the effects of carboplatin on macrophage phenotypes using both THP1- and peripheral blood mononuclear cell (PBMC)-derived macrophages and whether this supports CSCs and ovarian cancer progression following treatment. We found that carboplatin exposure induces an M1-like proinflammatory phenotype that promotes SOX2 expression, spheroid formation, and CD117+ ovarian CSCs, and that macrophage-secreted CCL2/MCP-1 is at least partially responsible for this effect. Depletion of TAMs during carboplatin exposure results in fewer CSCs and prolonged survival in a xenograft model of ovarian cancer. This study supports a role for platinum-based chemotherapies in promoting a transient proinflammatory M1-like TAM that enriches for CSCs during treatment. Improving our understanding of TME responses to cytotoxic drugs and identifying novel mechanisms of CSC maintenance will enable the development of better therapeutic strategies for high-grade serous ovarian cancer. Significance: We show that chemotherapy enhances proinflammatory macrophage phenotypes that correlate with ovarian cancer progression. Given that macrophages are the most prominent immune cell within these tumors, this work provides the foundation for future translational studies targeting specific macrophage populations during chemotherapy, a promising approach to prevent relapse in ovarian cancer.

Cruz LS ，Robinson M ，Stevenson D ，Amador IC ，Jordan GJ ，Valencia S ，Navarrete C ，House CD ... -  《-》

Cancer stem cell metabolism: a potential target for cancer therapy.

Deshmukh A ，Deshpande K ，Arfuso F ，Newsholme P ，Dharmarajan A ... -  《Molecular Cancer》