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	{{Short description\|Peptides used in targeted cancer therapy}}		{{Short description\|Peptides used in targeted cancer therapy}}
			{{Use dmy dates\|date=October 2023}}

	'''iRGD peptides''' are a class of [[~~peptide~~]]s that have been ~~developed for use in targeted~~ [[~~cancer therapy~~]]. These peptides are ~~designed to enhance~~ the ~~delivery of therapeutic agents to~~ [[~~tumor~~]]s by ~~exploiting~~ specific ~~molecular markers~~ that ~~are overexpressed in the tumor microenvironment~~. The iRGD peptide is ~~a modified version~~ of the RGD ~~peptide~~, ~~which is known for its ability to bind to integrins~~, ~~a type of cell surface receptor~~.		== Overview ==
			'''iRGD peptides''' are a class of [[cyclic peptides]] that have been engineered to enhance the delivery of therapeutic agents to [[tumor]] tissues. These peptides are derived from the [[C-end rule]] (CendR) motif, which is characterized by a specific sequence of amino acids that facilitate binding to [[neuropilin-1]] (NRP-1) receptors. The iRGD peptide sequence is typically composed of the integrin-binding motif RGD (Arg-Gly-Asp) followed by a CendR motif, such as R/KXXR/K, where X can be any amino acid.

	~~==Structure and Function==~~		[[File:IRGD.svg\|Diagram of iRGD peptide structure\|thumb\|right]]
	[[File:IRGD.svg\|~~Structure~~ of ~~the~~ iRGD peptide\|thumb\|right]]
	The iRGD peptide contains the sequence CRGDKGPDC, where the RGD motif is critical for binding to integrins. The "i" in iRGD stands for "internalizing," which refers to the peptide's ability to penetrate tissues and facilitate the internalization of attached therapeutic agents into cells. This is achieved through a multistep process that involves initial binding to integrins, followed by proteolytic cleavage and interaction with neuropilin-1, a receptor that mediates tissue penetration.

	==Mechanism of Action==		== Mechanism of Action ==
	The ~~mechanism~~ of ~~action~~ of ~~iRGD peptides involves several key steps:~~		The iRGD peptide functions through a multi-step process that enhances the penetration of drugs into tumor tissues. Initially, the RGD motif binds to [[integrins]] that are overexpressed on the surface of tumor endothelial cells. This binding facilitates the initial attachment of the peptide to the tumor vasculature. Following this, the peptide undergoes proteolytic cleavage, exposing the CendR motif. The exposed CendR motif then binds to NRP-1 receptors, which are also overexpressed in tumor tissues. This binding triggers a transvascular transport pathway, allowing the peptide and its conjugated therapeutic agents to penetrate deeply into the tumor parenchyma.

	~~# '''Integrin Binding:'''~~ The ~~RGD motif~~ in the ~~iRGD peptide binds to integrins~~, ~~which~~ are ~~overexpressed on~~ the ~~surface~~ of ~~tumor cells and the surrounding vasculature~~.		== Applications in Cancer Therapy ==
	~~# '''Proteolytic Cleavage:''' After binding,~~ the ~~peptide undergoes proteolytic cleavage~~, ~~which exposes a cryptic CendR motif (R/KXXR/K) that is recognized by neuropilin-1.~~		The primary application of iRGD peptides is in the field of [[cancer therapy]], where they are used to improve the delivery and efficacy of [[chemotherapeutic agents]]. By enhancing the penetration of drugs into tumors, iRGD peptides can increase the concentration of the drug at the target site, potentially reducing the required dosage and minimizing systemic side effects. iRGD peptides have been studied in combination with various anticancer drugs, including [[doxorubicin]], [[paclitaxel]], and [[cisplatin]].
	~~# '''Neuropilin-1 Binding:''' The interaction with neuropilin-1 facilitates~~ the ~~penetration~~ of the ~~peptide~~ and ~~any attached therapeutic agents into the tumor tissue~~.
	~~# '''Enhanced Permeability and Retention (EPR) Effect:''' The~~ iRGD ~~peptide enhances the EPR effect~~, ~~allowing for increased accumulation of drugs in the tumor site~~.

	==~~Applications in Cancer Therapy~~==		== Advantages and Challenges ==
	The ~~primary application~~ of iRGD peptides is in ~~the field of~~ cancer therapy, ~~where they~~ are ~~used to improve~~ the ~~delivery and efficacy~~ of ~~anticancer drugs. By targeting~~ the ~~tumor microenvironment specifically~~, ~~iRGD peptides can increase~~ the ~~concentration of therapeutic agents at~~ the ~~tumor site while minimizing systemic exposure and side effects~~.		The use of iRGD peptides offers several advantages in targeted cancer therapy. These include increased specificity for tumor tissues, improved drug penetration, and the potential for reduced systemic toxicity. However, there are also challenges associated with their use. These include the stability of the peptide in the bloodstream, potential immunogenicity, and the need for precise control over the peptide-drug conjugation process.

	==~~=Drug Conjugates=~~==		== Future Directions ==
	iRGD peptides ~~can be conjugated to various anticancer drugs~~, ~~nanoparticles, or imaging agents~~. ~~This conjugation allows for~~ the ~~targeted~~ delivery of ~~these agents~~, ~~enhancing their~~ therapeutic ~~index and reducing off-target effects~~.		Research into iRGD peptides is ongoing, with efforts focused on improving their stability and efficacy. Advances in [[peptide engineering]] and [[nanotechnology]] are being explored to enhance the delivery capabilities of iRGD peptides. Additionally, there is interest in combining iRGD peptides with other targeting strategies, such as [[antibody-drug conjugates]] and [[nanoparticles]], to further improve therapeutic outcomes.

	~~===Combination Therapies===~~		== Related Pages ==
	In addition to drug conjugates, iRGD peptides can be used in combination with other therapeutic modalities, such as [[immunotherapy]] and [[radiotherapy]], to improve treatment outcomes. The enhanced permeability and retention effect facilitated by iRGD can improve the delivery of immune cells or radiation to the tumor site.

	~~==Challenges and Future Directions==~~
	While iRGD peptides hold great promise for improving cancer therapy, there are several challenges that need to be addressed. These include optimizing the stability and bioavailability of the peptides, understanding the variability in response among different tumor types, and ensuring the safety and efficacy of iRGD-conjugated therapies in clinical settings.

	Future research is focused on developing new iRGD variants with improved properties, exploring their use in other diseases characterized by abnormal vasculature, and conducting clinical trials to validate their therapeutic potential.

	==Related Pages==
	* [[Peptide therapy]]		* [[Peptide therapy]]
	* [[Targeted drug delivery]]		* [[Targeted drug delivery]]
	* [[Integrin]]		* [[Integrin]]
	* [[Neuropilin~~-1]]~~		* [[Neuropilin]]
	* [[Cancer treatment]]

	[[Category:Peptides]]		[[Category:Peptides]]
	[[Category:Cancer treatments]]		[[Category:Cancer treatments]]

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{{Short description|Peptides used in targeted cancer therapy}}

'''iRGD peptides''' are a class of [[peptide]]s that have been developed for use in targeted [[cancer therapy]]. These peptides are designed to enhance the delivery of therapeutic agents to [[tumor]]s by exploiting specific molecular markers that are overexpressed in the tumor microenvironment. The iRGD peptide is a modified version of the RGD peptide, which is known for its ability to bind to integrins, a type of cell surface receptor.

==Structure and Function==
[[File:IRGD.svg|Structure of the iRGD peptide|thumb|right]]
The iRGD peptide contains the sequence CRGDKGPDC, where the RGD motif is critical for binding to integrins. The "i" in iRGD stands for "internalizing," which refers to the peptide's ability to penetrate tissues and facilitate the internalization of attached therapeutic agents into cells. This is achieved through a multistep process that involves initial binding to integrins, followed by proteolytic cleavage and interaction with neuropilin-1, a receptor that mediates tissue penetration.

==Mechanism of Action==
The mechanism of action of iRGD peptides involves several key steps:

# '''Integrin Binding:''' The RGD motif in the iRGD peptide binds to integrins, which are overexpressed on the surface of tumor cells and the surrounding vasculature.
# '''Proteolytic Cleavage:''' After binding, the peptide undergoes proteolytic cleavage, which exposes a cryptic CendR motif (R/KXXR/K) that is recognized by neuropilin-1.
# '''Neuropilin-1 Binding:''' The interaction with neuropilin-1 facilitates the penetration of the peptide and any attached therapeutic agents into the tumor tissue.
# '''Enhanced Permeability and Retention (EPR) Effect:''' The iRGD peptide enhances the EPR effect, allowing for increased accumulation of drugs in the tumor site.

==Applications in Cancer Therapy==
The primary application of iRGD peptides is in the field of cancer therapy, where they are used to improve the delivery and efficacy of anticancer drugs. By targeting the tumor microenvironment specifically, iRGD peptides can increase the concentration of therapeutic agents at the tumor site while minimizing systemic exposure and side effects.

===Drug Conjugates===
iRGD peptides can be conjugated to various anticancer drugs, nanoparticles, or imaging agents. This conjugation allows for the targeted delivery of these agents, enhancing their therapeutic index and reducing off-target effects.

===Combination Therapies===
In addition to drug conjugates, iRGD peptides can be used in combination with other therapeutic modalities, such as [[immunotherapy]] and [[radiotherapy]], to improve treatment outcomes. The enhanced permeability and retention effect facilitated by iRGD can improve the delivery of immune cells or radiation to the tumor site.

==Challenges and Future Directions==
While iRGD peptides hold great promise for improving cancer therapy, there are several challenges that need to be addressed. These include optimizing the stability and bioavailability of the peptides, understanding the variability in response among different tumor types, and ensuring the safety and efficacy of iRGD-conjugated therapies in clinical settings.

Future research is focused on developing new iRGD variants with improved properties, exploring their use in other diseases characterized by abnormal vasculature, and conducting clinical trials to validate their therapeutic potential.

==Related Pages==
* [[Peptide therapy]]
* [[Targeted drug delivery]]
* [[Integrin]]
* [[Neuropilin-1]]
* [[Cancer treatment]]

[[Category:Peptides]]
[[Category:Cancer treatments]]

IRGD peptides - Revision history

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