What Causes Drug Resistance in Cancer?

Drug resistance, also known as drug resistance, refers to the resistance of microorganisms, parasites and tumor cells to the effects of chemotherapeutic drugs. Once drug resistance occurs, the chemotherapeutic effect of drugs decreases significantly. Drug resistance can be divided into acquired resistance and natural resistance according to its cause. Pathogens in nature, such as certain strains of bacteria, can also be naturally resistant. When antibiotics are used for a long time, the majority of sensitive strains are continuously killed, and the resistant strains multiply in large numbers, replacing the sensitive strains, so that the resistance rate of bacteria to the drug continues to increase. The latter method is currently considered to be the main cause of drug-resistant bacteria. To maintain the effectiveness of antibiotics, their rational use should be valued.

Chinese name: Drug resistance
Foreign name: drug resistance

nickname: Drug resistance
Enzyme species: 2 kinds

The mechanism of drug resistance

Inactivated enzyme

There are two kinds of inactivating enzymes. One is hydrolase, such as -lactamase, which can hydrolyze penicillin or cephalosporin. The enzyme can be mediated by a chromosome or a plasmid. Some enzymes are constitutional (structural enzymes); some can be induced (inducible enzymes). two is

Inactivating enzymes, also known as synthetases, can catalyze the binding of certain groups to the OH or NH2 groups of antibiotics and inactivate antibiotics. Most gram-negative bacilli resistant to aminoglycoside antibiotics can produce plasmid-mediated inactivating enzymes, such as acetyltransferase acting on NH2 group, phosphotransferase and nucleoside transferase acting on OH group. The above enzymes are located in the outer space of the cytoplasmic membrane. After the aminoglycosides are inactivated by the above enzymes, they are not easy to bind to ribosomes in bacteria and cause drug resistance.

Drug resistance changes bacterial plasma membrane permeability

Bacteria can make it difficult for antibacterial drugs to enter the bacterial body through various ways. For example, the outer membrane of gram-negative bacilli has a natural barrier to penicillin G; Pseudomonas aeruginosa and other gram-negative bacilli cell wall water pores, or non-specific outer membrane Channel function changes, causing bacteria to be resistant to some broad-spectrum penicillins, cephalosporins, including some third-generation cephalosporins; bacteria's resistance to tetracycline is mainly due to the resistance plasmids that can induce three new Protein, blocking the cell wall water holes, making the drug inaccessible; in addition to the aforementioned inactivation enzymes, gram-negative bacteria are resistant to aminoglycosides, and because the cell wall water holes are changed, it is difficult for the drug to penetrate the bacteria.

Changes in target structure in drug-resistant bacteria

On the 30s subunit of bacterial ribosome of streptomycin-resistant strains, the P10 protein at the target site of streptomycin changes; the resistance to lincomycin and erythromycin is on the 23s subunit of bacterial ribosome The target protein is changed, which prevents the drug from binding to bacteria. Some Neisseria gonorrhoeae are resistant to penicillin G, and staphylococcus aureus is resistant to methicillin. The change in penicillin-binding protein caused by mutations makes it difficult for the drug to bind to it. This resistant strain is often resistant to other penicillins and cephalosporins.

Resistance to other

Bacterial resistance to sulfa drugs can be caused by the increase in the production of PABA, which has an antagonistic effect on the drug, and may also be caused by changing the demand for metabolites.

The difference between drug resistance and drug resistance

Drug resistance

It refers to the ability of the organism to produce immunity to certain substances in the body, so that it cannot harm itself. The generation of drug resistance is an adaptive change that occurs after the pathogen has been exposed to low-dose drugs for a long time. The pathogen produces enzymes that inactivate the drug, changes the permeability of the membrane and blocks drug entry, changes the target structure, or changes the original metabolic process. Mechanisms by which pathogens develop resistance.

Drug resistance

Generally refers to the susceptibility of the pathogen to the drug after repeated contact with the drug, or even disappear, resulting in a decrease or ineffectiveness of the drug on the pathogen. Microbes, parasites, and cancer cells can all develop resistance. The generation of drug resistance is an adaptive change that occurs after the pathogen has been exposed to low-dose drugs for a long time. The pathogen produces enzymes that inactivate the drug, changes the permeability of the membrane and blocks drug entry, changes the target structure, or changes the original metabolic process. Mechanisms by which pathogens develop resistance.

The difference between the two is whether you can hurt yourself, you can't hurt yourself, emergence is drug resistance, and there is a gradual decrease in immunity that manifests itself as drug resistance.

What are the symptoms of drug-resistant hepatitis B?

At present, the commonly used antiviral drugs are nucleoside (acid) analogs. Such drugs generally have drug resistance, and the treatment is long and the drug is easy to rebound. Therefore, drug resistance of hepatitis B virus will inevitably appear in antiviral treatment. Clinically, hepatitis B virus resistance includes three aspects: gene resistance, virological resistance, and biochemical resistance.

Gene resistance, resistance at the gene level does not show any clinical manifestations, hepatitis B virus DNA is still undetectable, but the virus gene was directly checked to find mutations in the resistance gene, such as lamivudine, we found the MDD immune strain appeared, and It is believed that resistance has emerged; as more and more resistant strains become dominant strains, there must be hepatitis B virus and the virus will be positive, which is virological resistance; with the emergence of virological resistance, transaminase may have Some will rebound, which is called biochemical resistance.

No matter what kind of drug resistance, the general symptoms are similar to the symptoms of hepatitis B, such as nausea, vomiting, pain in the liver area, low fever, hair loss, liver enlargement, and ascites. These symptoms are similar to those of ordinary patients. It is generally difficult to detect.

Today, drug resistance has become a major problem that plagues the medical community. Drug-resistant bacteria are generated much faster than the development of new human drugs, so it is imperative to develop new antibacterial drugs.