How does Chemoresistance occur?

Tumor chemoresistance is often driven by cancer stem cells (CSCs). These tumor-initiating cells have the ability to self-renew, and they make up a small proportion of the heterogenous tumor [7].

Why are cancer stem cells drug resistance?

Cancer stem cells (CSCs), also known as tumor-initiating cells (TICs), are suggested to be responsible for drug resistance and cancer relapse due in part to their ability to self-renew themselves and differentiate into heterogeneous lineages of cancer cells.

How can cancer stem cell CSC hypothesis contribute to cancer treatments?

The CSC hypothesis suggests that there is a small reservoir of cells within the tumor, which are resistant to many standard therapies, and can give rise to new tumors in the form of metastases or relapses after apparent tumor regression.

How does a cancer stem cell arise?

In (c) a mutation occurs in already formed blood cells that changes them into cancer cells. One or more subsequent mutations may reprogram cancer cells into cancer stem cells, which have regained stem cell characteristics; they can self-renew and give rise to new cancer blood cells.

Why does chemo work for some and not others?

There are several possible reasons for chemotherapy resistance: Some of the cells that are not killed by the chemotherapy mutate (change) and become resistant to the drug. Once they multiply, there may be more resistant cells than cells that are sensitive to the chemotherapy.

What does Chemoresistance mean?

: the quality or state of being resistant to a chemical (as a drug) chemoresistance in a series of lung adenocarcinoma samples— J. C. Willey et al.

What is are the characteristics of cancer stem cells?

Within the cancer population of the tumors there are cancer stem cells (CSC) that are tumorigenic cells and are biologically distinct from other subpopulations They have two defining features: their long-term ability to self-renew and their capacity to differentiate into progeny that is non-tumorigenic but still …

What is chemoresistance in cancer stem cells?

Chemoresistance of cancer stem cells may be linked to: Their frequent quiescent state with a low proliferation rate, since most conventional cytotoxic agents target proliferating cells [7,13,14,15]. Cancer stem cells niches have been identified, where cancer stem cells may be quiescent and chemo-resistant.

What is the difference between cancer cells and cancer stem cells?

One of the differences between normal stem cells and cancer stem cells is their degree of dependence on the stem cell niche, a specialized microenvironment in which stem cells reside.

Do cancer cells stop dividing?

Unlike normal cells, cancer cells don’t stop growing and dividing when there are enough of them.

Does cancer start in stem cells?

Stem cells survive much longer than ordinary cells, increasing the chance that they might accumulate genetic mutations. It might take only a few mutations for one cell to lose control over its self-renewal and growth and become the source of cancer.

What is the difference between cancer cells and stem cells?

What are the mechanisms of chemoresistance in breast cancer?

Re-expression of let-7 microRNA in breast cancer stem cells can promote CSCs entering differentiation phase from stationary phase and then enhance the sensitivity of CSCs to chemotherapeutics [ 42 ]. A series of breast cancer stem cells (BCSCs) surface markers, such as CD24, CD44, CD47]

Are there any resistance mechanisms for breast cancer?

A proportion of patients with breast cancer may relapse [ 2 ], there is an urgent need to have better understanding of the resistance mechanisms.

What are the signaling pathways for breast cancer?

The upstream signaling pathways, including epidermal growth factor receptor (EGFR), human epidermal growth factor receptor-2 (HER-2), insulin-like growth factor 1 receptor (IGF-1R), and the downstream signaling pathways, such as PI3K/AKT/mTOR, RAS /MAPK/ERK can result in the resistance to endocrine therapy for breast cancers [ 15 ].

What kind of protein is involved in breast cancer?

ATP-binding cassette (ABC) transporters include MDR-associated protein, such as P-glycoprotein (P-gp), multidrug resistance associated protein (MRP), ABCC subfamily, and breast cancer resistance protein, such as breast cancer resistance protein (BCRP), ABCG subfamily [ 10 ].

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