P-glycoprotein (P-gp) is a major factor in the multidrug resistance phenotype in cancer cells. P-gp is a protein that regulates the ATP-dependent efflux of a wide range of anticancer medicines and confers resistance. Due to its wide specificity, several attempts have been made to block the action of P-gp to restore the efficacy of anticancer drugs. The major goal has been to create molecules that either compete with anticancer medicines for transport or function as a direct P-gp inhibitor. Despite significant in vitro success, there are presently no drugs available in the clinic that can “block” P-gp–mediated resistance. Toxicity, unfavourable pharmacological interactions, and a variety of pharmacokinetic difficulties might all be the reason for the failure. On the other hand, P-gp has a significant effect in the body. It protects the vital organs from the entry of foreign bodies and other toxic chemicals. Hence, the inhibitors of P-gp should not hinder its action in the normal cells. To develop an effective inhibitor of P-gp, thorough background knowledge is needed in this field. The main aim of this review article was to set forth the merits and demerits of the action of P-gp on cancer cells as well as on normal cells. The influence of P-gp on cancer drug delivery and the contribution of P-gp to activating drug resistance were also mentioned.

Even though various treatment methods are available for cancer, the death curve is not reducing. The diagnosis of cancer at the fourth stage and drug resistance are the leading reasons for treatment failure and lower survival rates. In this review article, we summarize the possible pitfalls during cancer treatment in general, which mainly include multidrug resistance, and propose a hypothesis for colorectal cancer specifically. We also evaluate multidrug resistance in cancer in general and colorectal cancer in particular and hypothesize a concept based on combination therapy with 5-fluorouracil, curcumin, and lipids for the possible management of colorectal cancer. In addition, a hypothetical approach, combining a synthetic agent and a natural chemotherapeutic agent, to treating colorectal cancer is also discussed. This hypothesis could improve the management of colorectal cancer.

Colorectal cancer is considered the third most common cancer and the second leading cause of death globally. It has been proven that titanium dioxide nanoparticles produce oxidative stress and can lead to chronic inflammation, which could turn into diseases like cancer, cardiovascular disorders, diabetes, and so on. To evaluate the effect of 5-fluorouracil (5-FU) curcumin (CUR) conjugate coated with pectin on colorectal cancer induced by titanium dioxide nanoparticles (TiO₂-NPs) and dimethylhydrazine (DMH), male rats were administered TiO₂-NPs (5 mg/kg) orally and DMH (1 mg/kg) peritoneally for 70 days and treated with 5-FU (60 mg/kg) and CUR (240 mg/kg) conjugate (1:4 ratio) coated with pectin. The bodyweight of the animals was evaluated, and the blood sugar level was calculated. Further blood and plasma analyses were conducted. Hematological parameters, antioxidant parameters, and biochemical estimation were taken into consideration. The TiO₂-NPs level in the blood and colorectal region was also calculated. With the induction of colon cancer using TiO₂-NPs and DMH, a significant increase in the body weight of the animals was seen; eventually, with treatment, it was reduced. The bodyweight increase was due to an increase in the blood sugar level. There were also significant changes in the hematological parameters and biochemical estimation reports when comparing those of the positive control, negative control, and treated groups. No significant effect on biochemical estimation reports was seen. Conclusions: These reports suggest that 5-FU CUR conjugate coated with pectin helps in the management of colorectal cancer induced by TiO₂-NPs and DMH.